Three-dimensional printing device and method

Abstract

The present invention relates to a three-dimensional printing device and method, wherein the device comprises: a printing assembly and a platform; the printing assembly comprises: at least one developing assembly and a conveying unit; the developing assembly comprises: a developing medium rotating in a fixed direction; a developing engine for forming a latent image on the developing surface of the developing medium; a feeder for providing printing material to the latent image to form a printing material layer; the conveying unit comprises at least one conveying medium for adjusting the matching relationship between the conveying medium and the developing medium, and / or adjusting the matching relationship between the conveying medium and the developing medium to change the number of times the printing material layer is transferred from the developing medium to the platform, so that the printing material layer can be transferred to the platform during both the first and second strokes of the lateral relative movement of the printing assembly and the platform. The present invention enables printing to be performed during each lateral relative movement of the platform while the developing medium rotates in the same direction.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional printing, and in particular to a three-dimensional printing device and a printing method based on electrostatic imaging technology or magnetic imaging technology. Background Art

[0002] 3D printing technology creates 3D models by stacking layers. Electrostatic imaging (also known as electrophotography), a common technique in traditional 2D printing, uses a developer drum to selectively adsorb the print material through a charging process, an exposure imaging process, and a development process. During the transfer process, the print material is solidified and printed onto paper through heating. 3D model printing can be performed by replacing the paper with a platform that supports the 3D model. Because 3D models have multiple layers, the printing process requires the platform to move back and forth linearly to print and stack the layers. If one stroke is used for printing while the other reverse stroke is used only to reset the platform, printing efficiency is reduced. If the developer drum were to print in both the forward and reverse strokes of the platform's bidirectional linear reciprocating motion, the complexity of electrostatic imaging technology would require two sets of electrostatic generators and other components, such as developers or cleaners, to coordinate the forward and reverse printing. One of these sets would always be idle, reducing equipment utilization, increasing costs, and reducing reliability due to the complex structure. Furthermore, it would be difficult to miniaturize the developer drum. Summary of the Invention

[0003] The present invention provides a three-dimensional printing device and method, which can realize printing in each stroke of the lateral relative movement of the platform and the printing assembly under the condition that the developing medium keeps rotating in a fixed direction.

[0004] The technical solution adopted by the present invention to solve the technical problem is: providing a three-dimensional printing device, including a printing assembly and a platform capable of relative movement, the printing assembly including: at least one developing assembly and a conveying unit;

[0005] The developer assembly includes:

[0006] The developing medium rotates in a fixed direction;

[0007] a developing engine for forming a latent image on a developing surface of a developing medium;

[0008] A material feeder, used for supplying printing material to the latent image to form a printing material layer;

[0009] The conveying unit includes at least one conveying medium, which is used to adjust the matching relationship between the conveying medium and the developing medium, and / or adjust the matching relationship between the conveying media to change the number of times the printing material layer is transferred from the developing medium to the platform, so that the printing material layer can be conveyed to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

[0010] The transmission unit includes a transmission medium; the transmission medium is a transmission drum or a transmission belt, and the developing medium of the developing assembly is a developing drum or a developing belt; the transmission medium and the developing medium are arranged in conjunction with each other; during a first stroke of the relative transverse movement of the printing assembly and the platform, the printing material layer on the developing medium is directly transmitted to the platform by the developing medium; during a second stroke of the relative transverse movement of the printing assembly and the platform, the printing material layer on the developing medium is transferred from the developing medium to the transmission medium in the opposite direction of rotation of the developing medium, and then the transmission medium transmits the printing material layer to the platform; or,

[0011] The transmission unit includes a transmission medium, which is a conveyor belt; the printing assembly includes multiple developing assemblies, the developing media of the developing assemblies are developing drums or developing belts, and the rotation directions are the same; the transmission medium is arranged in conjunction with each developing medium; when the printing assembly and the platform move laterally relative to each other in the first stroke, the printing material layer on each developing medium is directly transmitted to the platform by each developing medium; when the printing assembly and the platform move laterally relative to each other in the second stroke, the printing material layer on each developing medium is transferred from the corresponding developing medium to the transmission medium with a rotation direction opposite to that of the developing medium to form a composite printing material layer, and then the composite printing material layer is transmitted to the platform by the transmission medium.

[0012] The conveying unit includes a first conveying medium and a second conveying medium. The first conveying medium maintains a preset distance from the developing medium and rotates in opposite directions. By adjusting the matching relationship between the second conveying medium and the first conveying medium, during a first stroke of relative lateral movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the first conveying medium. During a second stroke of relative lateral movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the first conveying medium and the transfer of the second conveying medium rotating in the opposite direction to the first conveying medium. Alternatively,

[0013] The conveying unit includes a first conveying medium and a second conveying medium. By adjusting the matching relationship between the first conveying medium and the developer medium, and / or the matching relationship between the second conveying medium and the developer medium and the first conveying medium, during a first stroke of lateral relative movement of the printing assembly and the platform, the printing material layer is transferred from the developer medium to the second conveying medium, which rotates in the opposite direction of the developer medium, and is conveyed to the platform by the second conveying medium. During a second stroke of lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developer medium to the platform via the first conveying medium, which rotates in the opposite direction of the developer medium, and the second conveying medium, which rotates in the opposite direction of the first conveying medium; or

[0014] The conveying unit includes a first conveying medium and a second conveying medium, the first conveying medium is a conveyor belt, and the second conveying medium is a conveyor drum or a conveyor belt; the printing assembly includes multiple developing assemblies, the developing media of the developing assemblies are developing drums or developing belts, and the rotation directions are all the same; each developing medium maintains a preset distance from the first conveying medium and rotates in the opposite direction to the first conveying medium; by adjusting the matching relationship between the second conveying medium and the first conveying medium, during the first stroke of the printing assembly and the platform moving horizontally relative to each other, the printing material layers formed by each developing medium are transferred from the corresponding developing medium to the first conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the first conveying medium; during the second stroke of the printing assembly and the platform moving horizontally relative to each other, the printing material layers formed by each developing medium are transferred from the corresponding developing medium to the first conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the first conveying medium through the second conveying medium rotating in the opposite direction to the first conveying medium.

[0015] The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium. The developing medium and the first conveying medium maintain a preset distance and rotate in opposite directions. The first conveying medium and the second conveying medium maintain a preset distance and rotate in opposite directions. By adjusting the matching relationship between the third conveying medium and the second conveying medium, the printing material layer is conveyed from the developing medium to the platform through the transfer of the first conveying medium and the transfer of the second conveying medium in the opposite direction of rotation to the second conveying medium, or the printing material layer is conveyed to the platform through the transfer of the first conveying medium, the second conveying medium, and the third conveying medium in sequence; or

[0016] The conveying unit includes a first conveying medium, a second conveying medium, and a plurality of third conveying media, each of which is a conveying drum, the first conveying medium is a conveying belt, and the second conveying medium is a conveying drum or a conveying belt; the printing assembly includes a plurality of developing assemblies, and the developing media of each developing assembly rotate in the same direction; each developing medium maintains a preset distance from the corresponding third conveying medium and rotates in the opposite direction; each third conveying medium maintains a preset distance from the first conveying medium and rotates in the opposite direction of the first conveying medium, and by adjusting the matching relationship between the second conveying medium and the first conveying medium, during a first stroke of relative transverse movement of the printing assembly and the platform, the printing material layers formed by each developing assembly are transferred from the corresponding developing medium to the first conveying medium through the corresponding third conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the first conveying medium; during a second stroke of relative transverse movement of the printing assembly and the platform, the printing material layers formed by each developing assembly are transferred from the corresponding developing medium to the first conveying medium through the corresponding third conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the transfer from the first conveying medium to the second conveying medium rotating in the opposite direction to the first conveying medium; or

[0017] The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium. The first conveying medium and the second conveying medium are respectively arranged in cooperation with different positions of the developer medium; the third conveying medium is arranged in cooperation with the first conveying medium. By adjusting the cooperation relationship between the first conveying medium and the developer medium, and / or the cooperation relationship between the second conveying medium and the developer medium, during the second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developer medium to the platform through the transfer of the first conveying medium in the opposite direction of rotation of the developer medium and the transfer of the third conveying medium in the opposite direction of rotation of the first conveying medium. During the first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developer medium to the platform through the transfer of the second conveying medium in the opposite direction of rotation of the developer medium; or

[0018] The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium. The first conveying medium and the second conveying medium are respectively arranged on both sides of the developing assembly. By adjusting the matching relationship between the first conveying medium and the developing medium, the matching relationship between the second conveying medium and the third conveying medium, and / or the matching relationship between the third conveying medium and the developing medium, during a first stroke of relative transverse movement of the printing assembly and the platform, the printing material layer is transferred from the developing medium to the platform via the first conveying medium in a direction opposite to the rotation direction of the developing medium. During a second stroke of relative transverse movement of the printing assembly and the platform, the printing material layer is transferred from the developing medium to the platform via the third conveying medium in a direction opposite to the rotation direction of the developing medium and the second conveying medium in a direction opposite to the rotation direction of the third conveying medium in sequence; or

[0019] The conveying unit includes a second conveying medium, a third conveying medium and a plurality of first conveying media, wherein the first conveying media are all conveying drums, and the second conveying medium and the third conveying medium are all conveying belts. The developing media of the plurality of developing assemblies are respectively arranged in cooperation with the corresponding first conveying medium, and the second conveying medium and the third conveying medium are respectively arranged on both sides of the plurality of developing assemblies and the first conveying medium. By adjusting the cooperation relationship between the second conveying medium and the first conveying medium, and / or the cooperation relationship between the third conveying medium and the developing medium, during the second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer respectively formed by each developing assembly is transferred from the corresponding developing medium to the platform through the first conveying medium in the opposite direction of rotation of the developing medium and the second conveying medium in the opposite direction of rotation of the first conveying medium. During the first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer respectively formed by each developing assembly is transferred from the corresponding developing medium to the platform through the third conveying medium in the opposite direction of rotation of the developing medium; or

[0020] The conveying unit includes a second conveying medium, a third conveying medium, and a plurality of first conveying media. The plurality of first conveying media are conveying drums, and the second conveying medium and the third conveying medium are conveying belts. The plurality of developing assemblies are arranged vertically, and the developing medium of each developing assembly is respectively arranged in conjunction with the corresponding first conveying medium. The second conveying medium and the third conveying medium are respectively arranged on both sides of the plurality of developing assemblies and the corresponding first conveying medium in the transverse direction. Each first conveying medium is arranged in conjunction with the second conveying medium, and each developing medium is arranged in conjunction with the third conveying medium. By adjusting the coordination relationship between the second conveying medium and the first conveying medium, and / or the coordination relationship between the third conveying medium and the developing medium, during the second stroke of the transverse relative movement of the printing assembly and the platform, the printing material layer formed by each developing assembly is transferred from the corresponding developing medium to the platform via the corresponding first conveying medium and the second conveying medium in the opposite direction of rotation of the first conveying medium. During the first stroke of the transverse relative movement of the printing assembly and the platform, the printing material layer formed by each developing assembly is transferred from the corresponding developing medium to the platform via the third conveying medium in the opposite direction of rotation of the developing medium.

[0021] Adjusting the coordination relationship between the transmission medium and the developing medium specifically includes: adjusting the adsorption force of the transmission medium on the printing material layer and / or adjusting the distance between the transmission medium and the developing medium; adjusting the coordination relationship between the transmission media specifically includes: adjusting the adsorption force of the transmission medium on the printing material layer and / or adjusting the distance between the transmission media.

[0022] The three-dimensional printing device adjusts the matching relationship between the transmission medium and the developing medium or another transmission medium by one of the following methods:

[0023] Method 1: The printing material layer has static electricity. A conductive layer or electrode is provided inside the transmission medium. The voltage or potential of the conductive layer or electrode is adjusted to adjust the electric field strength near the transmission medium to adjust the adsorption force of the transmission medium to the printing material layer on the developer medium or other transmission medium.

[0024] Method 2: The printing material layer has static electricity, and the outer surface of the transmission medium is an insulating layer. A charger and a dissipator are provided on the outer side of the transmission medium to adjust the static electricity on the surface of the transmission medium and thus adjust the adsorption force of the transmission medium to the printing material layer on the developer medium or other transmission media;

[0025] Method 3: The printing material layer is a magnetic material powder. A magnetic field control device is provided to adjust the magnetism and magnetic field strength of the transmission medium surface to adjust the adsorption force of the transmission medium to the printing material layer on the developing medium or other transmission medium.

[0026] In a fourth embodiment, the conveying unit further includes a position adjustment mechanism, the position adjustment mechanism being used to adjust the distance between the conveying medium and the developing medium, the distance between the conveying medium and other conveying media, or the distance between the conveying medium and the platform;

[0027] Mode 5: The transmission medium is a transmission drum, and the transmission unit further includes a swing mechanism, which is used to control the swing of the transmission drum to adjust the distance between the transmission drum, the developing medium or other transmission medium and the platform;

[0028] Method six: the transmission medium is a conveyor belt, and the transmission unit further includes a transfer roller; adjusting the distance between the conveyor belt and the developing medium or other transmission medium, adjusting the voltage of the transfer roller, or adjusting the magnetic field strength of the transfer roller.

[0029] In a first stroke of the lateral relative movement of the platform and the printing assembly, the distance between the transmission medium or developer medium that originally transmitted the printing material layer to the platform in the second stroke and the platform increases, and the increase is greater than the thickness of the printing material layer. In a second stroke of the lateral relative movement of the platform and the printing assembly, the distance between the transmission medium or developer medium that originally transmitted the printing material layer to the platform in the first stroke and the platform increases, and the increase is greater than the thickness of the printing material layer.

[0030] A cleaner and / or cooler is also provided downstream of the output position of the printing material layer of the conveying medium or the developing medium. The cleaner is used to clean the surface of the conveying medium or the developing medium, and the cooler is used to dissipate heat from the surface of the conveying medium or the developing medium.

[0031] The printing material layer transferred to the platform is cured and bonded to the platform or the solidified model on the platform in one of the following ways: Method 1, the printing material layer is a heat-fusible powder material, and the printing material layer is heated and extruded by the transmission medium or the developer medium and hot-pressed onto the platform or the solidified model on the platform; Method 2, the printing material layer is a heat-fusible powder material, and the heating beam is irradiated toward the platform through the transmission medium or the developer medium to heat the printing material layer in the extruded state, and the printing material layer is hot-pressed onto the platform or the solidified model on the platform; Method 3, the printing material layer is a heat-fusible powder material, and the heater heats the printing material layer. The printing material layer is heated to melt the printing material layer, and the developing medium or the conveying medium pressurizes the printing material layer toward the platform so that the printing material layer is combined with the platform or the cured model on the platform; the fourth method is that the printing material layer is a photosensitive resin liquid material that can be polymerized by light or a slurry material mixed with a photosensitive resin liquid and a powder material, and the curing light beam is transmitted through the conveying medium or the developing medium to irradiate the printing material layer toward the platform, and the printing material layer is polymerized and cured to be combined with the platform or the cured model on the platform; the fifth method is that the conveying medium is a conveyor belt, and the conveying unit further includes an extrusion roller; the extrusion roller is used to extrude the printing material layer onto the platform or the cured model on the platform.

[0032] A three-dimensional printing method, using the above three-dimensional printing device, during the printing process,

[0033] When the printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the transmission medium and the developing medium, and / or adjusting the matching relationship between the transmission media, so that the printing material layer generated by the developing assembly is transferred to the platform after N times;

[0034] When the printing assembly and the platform perform a second stroke of lateral relative movement, the conveying unit adjusts the conveying medium and the developing medium, and / or adjusts the matching relationship between the conveying media, so that the printing material layer generated by the developing assembly is transferred to the platform after N+1 transfers;

[0035] The printed material layers transferred to the platform are cured to achieve layer-by-layer bonding, and multiple layers of printed material are stacked and bonded to form the final solidified model;

[0036] Wherein, N is a natural number.

[0037] A three-dimensional printing device includes a printing assembly and a platform capable of relative movement, wherein the printing assembly includes a first developing assembly, a second developing assembly, and a conveying unit;

[0038] The first developing assembly includes:

[0039] A first developing medium rotates in a first fixed direction;

[0040] a first developing engine for forming a first latent image on a developing surface of a first developing medium;

[0041] A first feeder, configured to provide printing material to the first latent image to form a first printing material layer;

[0042] The second developing assembly includes:

[0043] a second developing medium, rotating in a second fixed direction;

[0044] a second developing engine for forming a second latent image on a developing surface of a second developing medium;

[0045] A second material feeder is used to provide printing material to the second latent image to form a second printing material layer;

[0046] The first fixing direction is opposite to the second fixing direction;

[0047] The conveying unit includes a first conveying medium and a second conveying medium. The first conveying medium maintains a preset distance from the first developing medium and rotates in opposite directions; the second conveying medium maintains a preset distance from the second developing medium and rotates in opposite directions. The conveying unit adjusts the matching relationship between the first conveying medium and the second conveying medium to change the number of transfers of the first printing material layer from the first developing medium to the platform and the number of transfers of the second printing material layer from the second developing medium to the platform, so that the first printing material layer and the second printing material layer can be conveyed to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

[0048] The first transmission medium is a first transmission drum, and the second transmission medium is a second transmission drum. The transmission unit adjusts the matching relationship between the first transmission medium and the second transmission medium specifically by: adjusting the adsorption force of the first transmission drum and the second transmission drum on the first printing material layer and the second printing material layer so that the adsorption force of the first transmission drum is greater than the adsorption force of the second transmission drum, so that the first printing material layer is transferred from the first developing medium through the first transmission drum to the platform, and the second printing material layer is sequentially transferred through the transfer of the second transmission drum and the transfer of the first transmission drum to the platform, or making the adsorption force of the second transmission drum greater than the adsorption force of the first transmission drum, so that the first printing material layer is transferred from the first developing medium through the transfer of the first transmission drum and the transfer of the second transmission drum to the platform, and the second printing material layer is transferred from the second developing medium through the transfer of the second transmission drum to the platform; or

[0049] The first transmission medium is a first conveyor belt, and the second transmission medium is a second conveyor belt. The first conveyor belt is arranged in conjunction with the first developing medium and has opposite rotation directions. The second conveyor belt is arranged in conjunction with the second developing medium and has opposite rotation directions. The rotation directions of the first conveyor belt and the second conveyor belt are opposite. The first conveyor belt is equipped with a first transfer roller, a third transfer roller and a first squeezing roller. The second conveyor belt is equipped with a second transfer roller, a fourth transfer roller and a second squeezing roller. The third transfer roller maintains a preset distance from the first developing medium and has opposite rotation directions, and is used to adsorb the first printing material layer to the first conveyor belt. The fourth transfer roller maintains a preset distance from the second developing medium and has opposite rotation directions, and is used to adsorb the printing material layer to the second conveyor belt. The first transfer roller The first transfer roller is arranged opposite to the second transfer roller and rotates in the opposite direction; the conveying unit adjusts the matching relationship between the first conveying medium and the second conveying medium specifically by: adjusting the adsorption force of the first transfer roller to be greater than the adsorption force of the second transfer roller, so that the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveyor belt, and the second printing material layer is conveyed to the platform through the transfer of the second conveyor belt and the transfer of the first conveyor belt in sequence, or adjusting the adsorption force of the second transfer roller to be greater than the adsorption force of the first transfer roller, so that the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveyor belt and the transfer of the second conveyor belt in sequence, and the second printing material layer is conveyed from the second developing medium to the platform through the transfer of the second conveyor belt; or,

[0050] The first transmission medium is a first conveyor belt, and the second transmission medium is a second conveyor belt. The first conveyor belt is equipped with a first transfer roller and a first squeezing roller, and the second conveyor belt is equipped with a second transfer roller and a second squeezing roller. The first transfer roller maintains a preset distance from the first developing medium and rotates in opposite directions, and is used to adsorb the first printing material layer to the first conveyor belt; the second transfer roller maintains a preset distance from the second developing medium and rotates in opposite directions, and is used to adsorb the second printing material layer to the second conveyor belt; the first squeezing roller and the second squeezing roller are also used to adjust the adsorption force on the first printing material layer and the second printing material layer; the conveying unit adjusts The coordination relationship between the first transmission medium and the second transmission medium is specifically as follows: adjusting the adsorption force of the first extrusion roller and the second extrusion roller on the first printing material layer and the second printing material layer so that the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt, and the second printing material layer is transferred to the platform in sequence through the transfer of the second conveyor belt and the transfer of the first conveyor belt, or the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt and the transfer of the second conveyor belt, and the second printing material layer is transferred from the second developing medium to the platform through the transfer of the second conveyor belt.

[0051] The conveying unit also includes a third conveying medium, which is located between the first conveying medium and the second conveying medium. The conveying unit adjusts the matching relationship between the third conveying medium and the first conveying medium and the second conveying medium so that the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveying medium, and the second printing material layer is conveyed from the second developing medium to the platform through the transfer of the second conveying medium and the transfer of the third conveying medium in the opposite direction of rotation of the second conveying medium, or the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveying medium and the transfer of the third conveying medium in the opposite direction of rotation of the first conveying medium, and the second printing material layer is conveyed from the second developing medium to the platform through the transfer of the second conveying medium.

[0052] The coordination relationship between the third transmission medium, the first transmission medium and the second transmission medium is adjusted as follows:

[0053] Adjusting the distance between the third transfer drum and the first transfer medium and the second transfer medium; or,

[0054] Adjusting the adsorption force of the first transmission medium and the third transmission medium on the first printing material layer, and the adsorption force of the second transmission medium and the third transmission medium on the second printing material layer; or

[0055] The third conveying medium is a third conveying drum. A charger is arranged on the surface of the third conveying drum in a direction relatively away from the platform to charge the surface of the third conveying drum with static electricity. As the third conveying drum rotates, the first printing material layer or the second printing material layer is adsorbed onto the surface of the third conveying drum at a position downstream in the direction of rotation and close to the first conveying medium or the second conveying medium. As the third conveying drum rotates to the platform, the first printing material layer or the second printing material layer is extruded and laid onto the platform. Then, as the third conveying drum continues to rotate, the static electricity on the surface of the third conveying drum is eliminated by the charger at the downstream position. Alternatively,

[0056] The third transmission medium is a third transmission belt, and the third transmission belt is equipped with a transfer roller and a squeezing roller, and the distance between the transfer roller and the first transmission medium and the second transmission medium is adjusted, and / or the adsorption force of the transfer roller on the printing material layer on the side close to the first transmission medium and the side close to the second transmission medium is adjusted; or

[0057] The third transmission medium is a third conveyor belt, and the third conveyor belt is equipped with a first transfer roller, a second transfer roller and an extrusion roller. The first transfer roller is set in conjunction with the first transmission medium, and the second transfer roller is set in conjunction with the second transmission medium. The adsorption force of the first transfer roller and the second transfer roller on the first printing material layer and the second printing material layer are adjusted respectively.

[0058] The distance between the third conveying medium and the platform is smaller than the distance between the first conveying medium or the second conveying medium and the platform by one or more printing material layers; or, the distance between the third conveying medium and the platform is equal to the distance between the first conveying medium or the second conveying medium and the platform.

[0059] A three-dimensional printing method employs the above-mentioned three-dimensional printing device. During the printing process, during a first stroke of lateral relative movement between the printing assembly and the platform, the coordination relationship between the first transmission medium and the second transmission medium is adjusted so that the first printing material layer is transferred to the platform after N transfers and the second printing material layer is transferred to the platform after N+1 transfers. During a second stroke of lateral relative movement between the printing assembly and the platform, the coordination relationship between the first transmission medium and the second transmission medium is adjusted so that the first printing material layer is transferred to the platform after N+1 transfers and the second printing material layer is transferred to the platform after N transfers; wherein N is a natural number.

[0060] During the printing process, the first printing material layer is transferred to the first transmission medium, and the second printing material layer is transferred to the second transmission medium;

[0061] The printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the matching relationship between the first transmission medium and the second transmission medium so that the second printing material layer is transferred from the second transmission medium to the first transmission medium, the first printing material and the second printing material form a composite printing material layer on the first transmission medium, and the composite printing material layer is transported to the platform by the first transmission medium;

[0062] The printing assembly and the platform move longitudinally relative to each other and move away from each other by a preset distance;

[0063] The printing assembly and the platform perform a second stroke of lateral relative movement, adjusting the matching relationship between the first transmission medium and the second transmission medium so that the first printing material layer is transferred from the first transmission medium to the second transmission medium, the first printing material and the second printing material form a composite printing material layer on the second transmission medium, and the composite printing material layer is transported to the platform by the second transmission medium;

[0064] The printing assembly and the platform move longitudinally relative to each other and move away from each other by a preset distance;

[0065] Repeat the above process, and the printing material layers transferred to the platform are cured to achieve layer-by-layer bonding. Multiple layers of printing material are stacked and combined to form the final solidified model.

[0066] A three-dimensional printing device includes a printing assembly and a platform capable of relative movement, wherein the printing assembly includes a first developing assembly and a second developing assembly;

[0067] The first developing assembly includes:

[0068] A first developing medium rotates in a first fixed direction;

[0069] a first developing engine for forming a first latent image on a developing surface of a first developing medium;

[0070] A first feeder, configured to provide printing material to the first latent image to form a first printing material layer;

[0071] The second developing assembly includes:

[0072] a second developing medium, rotating in a second fixed direction;

[0073] a second developing engine for forming a second latent image on a developing surface of a second developing medium;

[0074] A second material feeder is used to provide printing material to the second latent image to form a second printing material layer;

[0075] The first fixing direction is opposite to the second fixing direction;

[0076] By adjusting the matching relationship between the first developer medium and the second developer medium, changing the number of times the first printing material layer is transferred from the first developer medium to the platform, and changing the number of times the second printing material layer is transferred from the second developer medium to the platform, the first printing material layer and the second printing material layer can be transferred to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

[0077] The adjustment of the matching relationship between the first developing medium and the second developing medium specifically includes adjusting the adsorption forces of the first developing medium and the second developing medium on the first printing material layer and the second printing material layer respectively.

[0078] A three-dimensional printing method employs the above-mentioned three-dimensional printing device. During the printing process, during a first stroke of lateral relative movement between the printing assembly and the platform, the first developer medium and the second developer medium are adjusted so that the first printing material layer is transferred to the platform after N transfers, and the second printing material layer is transferred to the platform after N+1 transfers. During a second stroke of lateral relative movement between the printing assembly and the platform, the first developer medium and the second developer medium are adjusted so that the first printing material layer is transferred to the platform after N+1 transfers, and the second printing material layer is transferred to the platform after N transfers; wherein N is a natural number.

[0079] The printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the matching relationship between the first developer medium and the second developer medium so that the second printing material layer is transferred from the second developer medium to the first developer medium, the first printing material layer and the second printing material layer are formed on the first developer medium to form a composite printing material layer, and the composite printing material layer is transferred from the first developer medium to the platform;

[0080] The printing assembly and the platform move longitudinally relative to each other and away from each other by a preset distance;

[0081] The printing assembly and the platform perform a second lateral relative movement, adjusting the matching relationship between the first developer medium and the second developer medium so that the first printing material layer is transferred from the first developer medium to the second developer medium, the first printing material layer and the second printing material layer are formed on the second developer medium to form a composite printing material layer, and the composite printing material layer is transferred to the platform by the second developer medium;

[0082] The printing assembly and the platform move longitudinally relative to each other and away from each other by a preset distance;

[0083] Repeat the above process, and the printing material layers transferred to the platform are cured to achieve layer-by-layer bonding. Multiple layers of printing material are stacked and combined to form the final solidified model.

[0084] Beneficial effects

[0085] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0086] The present invention adjusts the matching relationship between the transmission medium and the developer medium, and / or the matching relationship between the transmission media, so that the developer medium can always rotate in the same direction during the printing process, without the need for forward and reverse rotation during the relative reciprocating motion of the printing assembly and the platform, and printing can be achieved during each lateral relative movement of the platform and the printing assembly, thereby improving printing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1a and Figure 1b The transfer drum and the developing drum are used to realize the reciprocating printing and the curing is carried out by irradiation. Figure 1a For the first stroke state, Figure 1b It is the second stroke state;

[0088] Figure 2a-2c The transfer drum and the developing drum are used to realize the reciprocating printing and the curing is performed by heat pressing. Figure 2a For the first stroke state, Figure 2b For the second stroke state, Figure 2c The platform moves to one end and moves vertically; Figure 3 Print schematics for multiple print assemblies in parallel;

[0089] Figure 4a and Figure 4b Schematic diagram of using two transfer drums and a developing drum to achieve printing in a coordinated reciprocating stroke and curing by radiation.

[0090] Figure 4aFor the first stroke state, Figure 4b It is the second stroke state;

[0091] Figure 5 It is a schematic diagram of the cooperation between multiple developing drums and the same transfer drum;

[0092] Figure 6 Schematic diagram of curing by hot pressing;

[0093] Figure 7a and Figure 7b Schematic diagram of another scheme using two transfer drums and a developing drum to achieve reciprocating printing and curing by radiation. Figure 7a For the first stroke state, Figure 7b It is the second stroke state;

[0094] Figure 8a and Figure 8b Schematic diagram of using two developing drums and a conveyor belt to achieve reciprocating printing. Figure 8a For the first stroke state, Figure 8b It is the second stroke state;

[0095] Figure 9a and Figure 9b Schematic diagram of using two conveyor belts and a developing drum to achieve reciprocating printing and curing by radiation.

[0096] Figure 9a For the first stroke state, Figure 9b It is the second stroke state;

[0097] Figure 10a and Figure 10b Schematic diagram of using two conveyor belts and a developing drum to achieve reciprocating printing and curing through heat pressing.

[0098] Figure 10a For the first stroke state, Figure 10b It is the second stroke state;

[0099] Figure 11a and Figure 11b Schematic diagram of using a conveyor belt and a conveyor drum in conjunction with a developing drum to achieve reciprocating printing. Figure 11a For the first stroke state, Figure 11b It is the second stroke state;

[0100] Figure 12a and Figure 12b Schematic diagram of using a conveyor belt and a conveyor drum corresponding to each developing drum to cooperate with each other to achieve reciprocating printing. Figure 12a For the first stroke state, Figure 12b It is the second stroke state;

[0101] Figure 13aand Figure 13b Schematic diagram of reciprocating printing achieved by setting two conveyor belts and one conveyor belt on the upper and lower sides of the developing drum respectively. Figure 13a For the first stroke state, Figure 13b It is the second stroke state;

[0102] Figure 14 13 is a schematic diagram of an embodiment in which a conveyor belt on the upper side is replaced with a conveyor drum corresponding to each developing drum;

[0103] Figure 15 exist Figure 14 A schematic diagram of an embodiment of maintaining a preset gap between an upper conveyor belt and a conveyor drum and adopting radiation curing;

[0104] Figure 16a and Figure 16b Schematic diagram of the development drum cooperating with the right conveyor belt and the development drum cooperating with the left conveyor belt to achieve reciprocating printing. Figure 16a For the first stroke state, Figure 16b It is the second stroke state;

[0105] Figure 17a and Figure 17b A schematic diagram showing how two developing drums cooperate with the transfer drums and how the two transfer drums cooperate with each other to achieve reciprocating printing. Figure 17a For the first stroke state, Figure 17b It is the second stroke state;

[0106] Figure 18 A schematic diagram illustrating the cooperation between two developing drums to achieve reciprocating printing;

[0107] Figure 19a and Figure 19b Schematic diagram showing that two developing drums cooperate with the transfer drum and the third transfer drum to realize two-layer parallel reciprocating printing. Figure 19a For the first stroke state, Figure 19b It is the second stroke state;

[0108] Figure 20 Indicate Figure 19a or Figure 19b Schematic diagram of an embodiment in which the third conveyor drum is replaced with a conveyor belt and printing of a same-layer composite material is achieved;

[0109] Figure 21a and Figure 21b A schematic diagram showing at least two developing drums respectively cooperating with corresponding conveyor drums and conveyor belts and a third conveyor belt to realize two-layer parallel reciprocating printing. Figure 21a For the first stroke state, Figure 21b It is the second stroke state; Figure 22FIG21 is a schematic diagram of another embodiment of the present invention;

[0110] Figure 23a and Figure 23b A schematic diagram showing two developing drums passing through corresponding conveyor belts and the two conveyor belts cooperating with each other to realize reciprocating printing. Figure 23a For the first stroke state, Figure 23b It is the second stroke state;

[0111] Figure 24 for Figure 23a and Figure 23b A schematic diagram of another embodiment shown;

[0112] Figure 25a and Figure 25b Schematic diagram of using developing medium as developing belt and cooperating with conveyor belt to realize reciprocating printing. Figure 25a For the first stroke state, Figure 25b It is the second stroke state;

[0113] Figure 26 A schematic diagram illustrating how two developing belts cooperate with each other to achieve reciprocating printing. DETAILED DESCRIPTION

[0114] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0115] The present invention provides a three-dimensional molding device comprising a printing assembly and a platform. Printing can be achieved in both strokes of the reciprocating lateral movement between the printing assembly and the platform, i.e., a printing material layer can be transferred (transferred) onto the platform. The reciprocating lateral movement includes a first stroke and a second stroke, with the first and second strokes being in opposite directions. For example, if the first stroke is a forward stroke, the second stroke is a reverse stroke, and if the first stroke is a reverse stroke, the second stroke is a forward stroke, with the forward and reverse strokes being relative. The printing assembly comprises at least one developing assembly and a transport unit, the transport unit comprising at least one transport medium, or the printing assembly comprises at least two developing assemblies. The developing assembly is used to generate a printing material layer with a corresponding pattern based on layer pattern information of a three-dimensional model (cured model), and the transport medium is used to transfer the printing material layer. The developing assembly and the transport medium cooperate to transport (or lay, or transfer) the printing material layer onto the platform. The transport medium can be a transport drum or a transport belt. The developing assembly comprises a developing medium, a developing engine, and a feeder, and the developing medium can be a developing drum or a developing belt. Both the developer medium and the transport medium can rotate in a circular motion. The developer engine is used to form a latent image (such as an electrostatic latent image or a magnetic latent image) on the developer drum's developing surface. For example, the developer drum rotates about its axis, as indicated by the first arrow. The feeder is used to deposit a layer of printing material onto the developing surface of the developer drum corresponding to the latent image. The developing surface of the developer drum refers to the surface on the drum that can form a latent image and utilize this latent image to selectively attract the printing material layer. During the printing process, the developer medium rotates in a fixed direction, meaning it always rotates in the same direction or temporarily stops, but does not change direction, such as from clockwise to counterclockwise or vice versa. The print assembly and the platform are capable of relative movement, including longitudinal relative movement (also known as vertical relative movement) and lateral relative movement. The directions of longitudinal and lateral relative movement are substantially perpendicular to each other. Longitudinal relative movement refers to relative movement perpendicular to the platform surface to adjust the distance between the print assembly and the platform, such as increasing the distance based on layer thickness or decreasing the distance as needed. Longitudinal relative movement between the print assembly and the platform can be achieved by movement of the print assembly, the platform, or both. Lateral relative movement refers to movement of the print assembly relative to the platform in a direction parallel to the platform surface, movement of the platform in a direction opposite to that direction, or both simultaneously. Lateral relative movement between the print assembly and the platform includes a first stroke and a second stroke, with the first stroke and the second stroke being in opposite directions. For example, if the first stroke involves the print assembly moving left or the platform moving right, the second stroke involves the print assembly moving right or the platform moving left. Alternatively, if the first stroke involves the print assembly moving right or the platform moving left, the second stroke involves the print assembly moving left or the platform moving right.

[0116] During the printing process, during a first stroke of the lateral relative movement of the print assembly and the platform (e.g., the forward stroke), a print material layer generated by the developer assembly is transferred onto the platform N times. Then, during a second stroke of the lateral relative movement of the print assembly and the platform (e.g., the reverse stroke), a developer material layer generated by the developer is transferred onto the platform N+1 times. N is a positive integer including 0, i.e., N=0, 1, 2, ..., i.e., N is a natural number. When N is 0, it indicates that the print material layer is directly transferred (i.e., laid) onto the platform by the developer medium without undergoing a transfer process via the transfer medium. When N is 1, it indicates that the print material layer undergoes a single transfer process via the transfer medium, and so on. Furthermore, during the printing process, the developer drum or developer belt can always rotate in the same direction, eliminating the need for forward and reverse adjustments during the reciprocating relative movement of the print assembly and the platform (e.g., the first stroke and the second stroke). The developer medium or the transfer medium that finally transfers the print material layer onto the platform and the platform always maintains a substantially pure rolling fit, thereby enabling printing to be performed during both the first and second strokes of the lateral relative movement between the print assembly and the platform, thereby improving printing efficiency. The printing material layer transferred to the platform is combined by a suitable curing method, and multiple layers of printing material are stacked and combined to form a final cured model. Among them, the curing method can be a light beam irradiation or heating and pressurizing method. The printing material layer can be a photosensitive resin liquid, or a mixed slurry of photosensitive resin liquid and other powder materials, or a resin powder material (such as a thermoplastic powder material), or a metal powder material, or a ceramic powder material, or a mixed material of a resin powder material and a metal or ceramic powder material, or other powder materials. The developing engine can use electrostatic imaging technology or magnetic imaging technology to form a latent image on the developing surface of the developing medium, and the latent image can be an electrostatic latent image or a magnetic latent image. The developing medium or the transmission medium finally transfers the printing material layer to the platform, which means transferring it to the molding surface of the platform, such as the first layer of printing material layer, or it can be transferred to the printing material layer (or called a cured model) that has been laid on the platform. The process of conveying the printing material layer to the platform is the process of laying and transferring the printing material layer to the platform, and it is conveyed to the platform in the best flatness, without wrinkles or stretching. Therefore, the rotation direction of the developing medium or the conveying medium that finally conveys the printing material layer to the platform matches the direction of the lateral relative movement of the platform, that is, the developing medium or the conveying medium maintains a basically pure rolling cooperation state with the platform.

[0117] The coordination or coordinated arrangement of the transmission medium (such as a transmission drum or a transmission belt) and the developer medium (such as a developer drum or a developer belt) means that the transmission medium and the developer medium maintain a preset spacing (≥0), the respective rotation axes of the transmission medium and the developer medium are substantially parallel to each other, the transmission medium and the developer medium rotate in opposite directions when transferring a layer of printed material, and optimally, the rotation speeds of the outer surfaces of the transmission medium and the developer medium are matched so that the printed material does not wrinkle or stretch when transferred, that is, a smooth transfer is achieved. The coordination or coordinated arrangement of the transmission medium and the transmission medium means that the transmission medium and the transmission medium maintain a preset spacing (≥0), the respective rotation axes of the transmission medium and the transmission medium are substantially parallel to each other, the transmission medium and the developer medium rotate in opposite directions when transferring a layer of printed material, and optimally, the rotation speeds of the outer surfaces of the transmission medium and the transmission medium are matched so that the printed material does not wrinkle or stretch when transferred, that is, a smooth transfer is achieved. The developer medium is coupled or arranged in a coordinated manner, meaning that the developer medium maintains a predetermined spacing (≥0), the respective rotational axes of the developer medium and the developer medium are substantially parallel to each other, the developer medium rotates in opposite directions during the transfer of the print material layer, and optimally, the rotational speeds of the outer surfaces of the developer medium and the developer medium are matched so that the print material is not wrinkled or stretched during transfer, i.e., a smooth transfer is achieved. The cooperating media (e.g., developer medium or transfer medium) always rotate in opposite directions during the transfer of the print material layer, for example, if one rotates clockwise, the other rotates counterclockwise. The coordination relationship between the media (e.g., developer medium or transfer medium) can also be adjusted, which can be used to adjust the number of transfers of the print material layer to the platform, as well as the path of transfer and transport of the print material layer to the platform. The number of transfers of the print material layer generated by the developer assembly to the platform can be changed by adjusting the coordination relationship between the transfer medium and the developer medium, between the developer media, and / or between the individual transfer media. Adjusting the coordination between the transmission medium and the developer medium can be achieved by adjusting the adsorption force of the transmission medium on the print material layer, the adsorption force of the developer medium on the print material layer, and / or adjusting the spacing between the transmission medium and the developer medium. Adjusting the coordination between the various transmission media can be achieved by adjusting the adsorption force of each transmission medium on the print material layer and / or adjusting the spacing between the various transmission media. For example, by controlling the magnitude of the electric or magnetic field attached to the corresponding media or the spacing between the media, switching control and adjustment can be achieved as to whether the print material layer is transferred from the developer medium or the transmission medium to the other transmission medium. The magnetic field of the corresponding media can be controlled by a magnetic field control device, such as a magnetic head or an electromagnet. For example, an electromagnet can be provided on the inner side of the transmission medium to adjust the magnetic field strength attached to the outer surface of the transmission medium. The rotational speed or direction of the transmission medium or the developer medium can also be adjusted to adjust the coordination between them.By matching the rotation speed or direction of the transport medium or developer medium with the lateral relative movement speed and direction of the print assembly and the platform, the printed material layer is not "torn" or "wrinkled" when it is transported (transferred) to the platform, achieving precise printing.

[0118] Figure 1a and Figure 1b The present invention illustrates an embodiment of a three-dimensional printing device and a development process based on xerograph technology. The development medium is a development drum 36 and includes an outer photoconductive layer 11 and an inner conductive layer 12. The photoconductive layer 11 and the conductive layer 12 are bonded to each other. The development drum 36 rotates in a predetermined fixed direction, as indicated by a first arrow 91. A development engine and a feeder 2 are sequentially arranged in the direction of rotation. The feeder 2 contains printing material. The development engine can be as shown in FIG. Figure 1a The device shown comprises a charger 13 (or electrostatic generator) and a developing light source 31. Charger 13 is located upstream of developing light source 31. Charger 13 charges the photoconductive layer 11 of developing drum 36 with static electricity. Light source 31 emits a beam 39 based on the layer pattern information, selectively irradiating photoconductive layer 11. The illuminated areas of photoconductive layer 11 become conductive, and the static electricity in these areas is released by conductive layer 12, electrically connecting them to an electrode at a predetermined potential. Areas of photoconductive layer 11 not irradiated by the beam remain insulated, retaining static electricity therein, thereby forming an electrostatic latent image. As developing drum 36 rotates, it selectively attracts the printing material supplied by feeder 2 based on this electrostatic latent image, forming a developed pattern formed by the printing material layer 79 on the developing surface of developing drum 36. Figure 1a The figure shows that the transmission medium adopts a transmission drum 41 and is arranged in conjunction with the developing drum 36. The transmission drum 41 rotates in opposite directions to the developing drum 36. The printing material layer 79 is transferred from the developing drum 36 to the transmission drum 41. The developing assembly 10 includes the developing drum 36 and the developing engine. The printing assembly includes the developing assembly 10 and the transmission drum 41. During the lateral relative movement of the printing assembly and the platform 51, the transmission drum 41 transmits the printing material layer 79 to the platform 51, that is, to the molding surface of the platform 51. The so-called molding surface refers to the surface on the platform 51 that receives the printing material layer, or the surface on the cured model 71 on the platform 51 that ends the printing material layer. For example, Figure 1a In the second stroke state, the platform moves leftward along arrow 92, the developing drum 36 rotates counterclockwise along arrow 91, and the transfer drum 41 rotates clockwise along arrow 93. The printing material layer 79 is transferred from the developing drum 36 to the transfer drum 41, and the transfer drum 41 transfers it to the platform 51. Figure 1b In the first stroke state shown, the platform 51 moves to the right along the arrow 92. Figure 1aAs shown, the printing assembly moves laterally relative to the printing assembly, and the printing material layer 79 is transferred from the developing drum 36 to the forming surface on the platform 51. That is, in the two strokes of the platform 51's repeated lateral movement relative to the printing assembly, the printing assembly can achieve a smooth transfer of the printing material layer to the platform 51, and the rotation direction of the developing drum 36 does not need to be changed, which not only improves the printing efficiency but also simplifies the transposition structure and control process.

[0119] There are many ways to control whether the printing material layer 79 passes through the conveying drum 41. For example, the conveying drum 41 may include an insulating layer 11a and an inner conductive layer 12a. A high electric field is established between the conductive layer 12a and the conveying drum 41. For example, the conductive layer 12a is connected to a corresponding high-voltage electrode. By controlling the on or off state of the conductive layer 12a and the corresponding high-voltage electrode, the establishment and elimination of the electric field can be controlled, thereby controlling whether the printing material layer 79 is transferred to the conveying drum 41. In this method, the conductive layer 12a and the high-voltage electrode constitute an adsorption force control mechanism, which can adjust the adsorption force of the conveying drum 41 on the printing material layer 79, thereby controlling whether the printing material layer 79 is transferred to the conveying drum 41. In addition, it is also possible to Figure 1a Or 1b shows that the charger 13a is used to generate higher static electricity on the surface of the conveying drum 41 to adsorb the printing material layer 79. In another stroke, when the printing material layer 79 does not need to pass through the conveying drum 41, the eliminator 15a can eliminate the precision of the surface of the conveying drum 41. In this method, the charger 13a and the eliminator 15a constitute an adsorption force control mechanism.

[0120] The printed material layer 79 transferred to the platform 51 can be bonded together by light irradiation or heat pressing. Figure 1aThe conveyor drum 41 is permeable to light beam 891, which irradiates the print material layer 79 being laid onto the platform 51. If the print material layer 79 comprises a meltable powder material, light beam 891 may be a heating beam such as a laser or infrared light, which heats and melts the print material layer 79, causing it to fuse to the platform 51 or to bond with the previous print material layer and detach from the conveyor drum 41. If the print material layer 79 comprises a photosensitive resin liquid or a slurry of a photosensitive resin liquid and powder material, light beam 891 may be a curing beam that triggers a photopolymerization reaction. When irradiated, the print material layer 79 undergoes photocuring, and the cured print material layer 79 bonds to the platform 51 or to the previous print material layer and detaches from the conveyor drum 41. Light beam 891 may heat the conveyor drum 41. A cooler 822 may also be provided at the output position of the printing layer of the transmission medium or the developer medium. The output position of the printing layer of the transmission medium or the developer medium refers to the position on the transmission medium or the developer medium where the printing layer is transferred to the platform, for example, to dissipate heat from the transmission drum 41. A cleaner 14a may also be provided to clean the surface of the transmission drum 41. After each layer of printing is completed, the platform 51 moves along the arrow 93 to increase the distance between the printing assembly and the platform 51, and then Figure 1b In, with Figure 1a Similarly, light beam 891 passes through the developing drum 36 and irradiates the printing material layer 79, then bonds to the platform 51 or the previous printing material layer and detaches from the developing drum 36. A cleaner 14 or a static eliminator 15 can also be provided upstream of the charger 13 in the direction of rotation of the developing drum 36 to clean the surface of the developing drum and eliminate static electricity, preparing for the subsequent developing process. A cooler 821 can also be provided upstream of the feeder 2 in the direction of rotation of the developing drum 36 to dissipate heat from the developing drum. The distance between the platform and the printing assembly can then be adjusted, as shown in FIG. Figure 1a The next layer is printed in this way. This is repeated until the model 71 is printed. In addition, the developing drum 36 and the transfer drum 41 can also transfer the printed material layer 79 to the platform 51 through corresponding additional transfer drums or conveyor belts.

[0121] The developer drum, transfer drum, and platform coordinate with each other. Specifically, the spacing between the developer drum 36 and the platform 51 is properly controlled so that when the print material layer 79 is located between the developer drum 36 and the platform 51, the print material layer 79 can contact the platform 51 or the cured model 71 thereon. This facilitates direct bonding of the print material layer 79 to the platform 51 or the cured model 71 during curing by the light beam 891, and separation and "tearing" of the print material layer 79 from the surface of the developer drum 36. Furthermore, the rotational speeds of the developer drum 36 or transfer drum 41 are properly controlled to match each other and the speed of the platform movement, respectively. This minimizes slippage or "wrinkling" of the print material layer 79 when it is transferred to the transfer drum 41 or laid onto the platform 51. This maintains a pure rolling engagement between the developer drum 36 and the transfer drum 41 or the platform 51, thereby improving molding accuracy. The light beam 891 does not need to be selective; it only needs to cure the print material layer 79. It should be noted that in the present invention, the printing material layer 79 is laid on the platform 51, which may mean directly on the platform 51 (for example, for the first layer of printing material), or it may be laid on the solidified model 71 on the platform 51 (for example, for the second and subsequent layers of printing material).

[0122] Figure 2a and 2b The embodiment shown is Figure 1a Or 1b, the difference is that a heater is set on the outside of the transfer drum and the developing drum and the printing material layer 79 is bonded to the platform 51 by hot pressing. The printing material layer 79 formed by the developing drum 36 can be made of powder material. When it is laid on the platform 51, the printing material layer 79 can also be heated, for example, by heating it through the heater 813, so that the printing material layer 79 of the powder material melts. At the same time, the developing drum 36 can be appropriately pressurized toward the platform 51 so that the printing material layer 79 is bonded to the model 71 on the platform 51. Figure 2a The developing drum 36 is shown laying the printing material layer 79 directly onto the platform 51. A cooler 821 can be provided to cool the surface of the developing drum 36 after laying the printing material layer, so as to prepare for subsequent development and forming the printing material layer seat. A heater 811 and a cooler 822 can also be provided on the left side of the developing assembly 10 from right to left. The printing material layer laid onto the platform 51 can be further heated and melted by the heater 811 to enhance the bonding effect between the layers. The cooler 822 cools the printing material layer on the platform 51 to prepare for the subsequent laying of the printing material layer. When the platform 51 moves to the far left along the arrow 92, the platform 51 can be lowered by one layer and then move back to the right. Figure 2bAs shown, at the same time, the print material layer 79 formed by the developing drum 36 in the developing assembly 10 is first transferred to the transfer drum 41. The transfer drum 41 rotates along the direction of arrow 93, and the rotation direction is opposite to the rotation direction of the developing drum. The print material layer 79 is hot-pressed onto the platform 51 by the transfer drum 41. For example, a heater 814 can be provided upstream of the transition point between the rotating drum and the platform to preheat and heat the print material layer on the transfer drum 41. Similarly, a heater 812 and a cooler 823 can be provided in sequence from left to right on the right side of the developing assembly 10 to heat and dissipate heat to the print material layer laid on the platform. Since the cooler 821 is provided between the developing drum and the transfer drum, it can also dissipate heat from the surface of the transfer drum 41 where the completed print material layer is transferred to the platform. Figure 2a It is also indicated that the transfer drum 41 can be slightly moved up or the developing drum 36 can be moved toward the platform, so that the distance between the transfer drum and the platform is greater than the distance between the developing drum and the platform, to avoid the transfer drum and the platform 51 or the model 71 thereon from contacting and rubbing during the printing process and affecting the printing accuracy. Figure 2b The diagram illustrates a slight movement of the transfer drum 41 toward the platform or a slight movement of the developer drum away from the platform, such that the distance between the developer drum and the platform is greater than the distance between the transfer drum and the platform. This prevents friction between the developer drum and the platform 51 or the mold 71 thereon during printing, which could affect printing accuracy. The slight movement of the transfer drum 41 can be achieved by providing a position adjustment mechanism for the transfer drum 41. Figure 2c It shows that when the platform 51 moves to the rightmost position, the developing drum 36 and the transfer drum 41 are Figure 2b The state shown is adjusted to the state where the developing drum is low and the conveying drum is high. Specifically, the conveying drum and the developing drum can be rotated as a whole around the midpoint of the line 96 connecting the axes of the two. In this way, after each layer is printed, the platform 51 can be lowered by a distance of one layer. Alternatively, the conveying drum 41 can be swung around the rotation axis of the developing drum. When the conveying drum is swung upward (such as Figure 2c As shown, the platform 51 moves upward (e.g., along arrow 94) until the distance between the upper surface of the mold 71 and the surface of the developer drum is a predetermined value, such as the layer thickness distance. When the transfer drum is in a downward swinging state, the platform 51 moves downward (e.g., along arrow 94) until the distance between the upper surface of the mold 71 and the surface of the transfer drum is a predetermined value, such as the layer thickness distance. The swinging of the transfer drum 41 can be achieved by providing a swing mechanism for the transfer drum 41. By using the swing mechanism to adjust the distance between the transfer drum or developer drum and the platform, vertical movement of the developer assembly 10 can be avoided, thereby improving the reliability of the developer assembly 10 and simplifying the structure.

[0123] Figure 3The diagram also illustrates that multiple printing assemblies can simultaneously transfer printing material layers to the platform 51. For example, a first printing assembly can include a second developing assembly 10-1 and a second transfer drum 41-1, with a first printing material layer 79-1 formed and transferred to the platform 51 by the developing drum or via the transfer drum. A second printing assembly can include a second developing assembly 10-2 and a second transfer drum 41-2, with a second printing material layer 79-2 formed and transferred to the platform 51. The two printing assemblies can print on the same printing material layer, for example, printing different materials to form a composite material model 71, or printing different layers to increase printing speed. The figure also illustrates that a first electrode 49-1 can be positioned within the first transfer drum 41-1 near the developing assembly 10-1. When the first electrode 49-1 is controlled to establish a high electric field between the first electrode 49-1 and the developing assembly 10-1, the first electrode 49-1 can attract the printing material layer and transfer it to the first transfer drum 41-1. Similarly, a second electrode 49-2 can be positioned within the second transfer drum 41-2. It is also possible to illuminate the print material layer using light beams 891-1 and 892-2 through the first transfer drum and the second transfer drum, respectively.

[0124] Figure 3The schematic developing assembly can also employ ion injection or magnetography to form a latent image based on the layer pattern of the 3D model to be printed. If ion injection is employed, using the first developing assembly 10-1 as an example, compared to the previously described embodiment, the developing engine eliminates the charger 13 and the developing light source 31. Instead, an ion (or charge) injector 34-1 is employed. The surface of the developing drum 36 is an insulating layer, and the conductive layer 12 of the previously described embodiment need not be disposed on the inner surface. As the developing drum 36 rotates, the developing engine selectively injects ions onto the developing surface of the developing drum 36 based on the layer pattern information of the pre-printed model, forming a charge deposit and forming an electrostatic latent image on the developing surface of the developing drum 36. A charge eliminator 15-1 is also disposed upstream of the ion (or charge) injector 34-1 in the direction of the developing drum's rotation to eliminate static electricity on the developing drum's surface, thereby preparing for the subsequent formation of a new electrostatic latent image. If magnetography is used, the ion (or charge) injector 34-1 is replaced by an imaging head, and the charge eliminator 15-1 is replaced by a degaussing device. The surface of the developing drum is composed of a magnetic material layer. As the developing drum rotates, the imaging head forms a corresponding magnetic latent image on the drum surface. The printing material layer formed by the feeder 2-1 on the developing drum surface is a magnetic material powder (a material powder that interacts with the magnetic field). Using ion injection or magnetography can eliminate the charger 13, simplifying the structure. The photoconductive layer 11 can also be replaced by other transparent and insulating material layers, making it easier to implement. Furthermore, magnetography is more conducive to printing and forming magnetic materials. When using ion injection (ionography), the transfer drum can have the same structure as when using electrostatic imaging technology. When using magnetography (magnetography), the transfer drum's suction force control mechanism can be composed of a magnetic head and a degaussing device.

[0125] Figure 4a and Figure 4b It is shown that two transfer drums and one developing assembly 10 are provided in the same printing assembly, wherein the first transfer drum 41 - 1 cooperates with the developing drum 36 , and the second transfer drum 41 - 2 cooperates with the first transfer drum 41 - 1 , and the cooperation relationship is adjustable. Figure 4aIn the example, the printing assembly is assumed to move leftward along arrow 92, the developing drum rotates clockwise along arrow 91, and the first transfer drum 41-1 rotates counterclockwise along arrow 93, with the direction of rotation of arrow 93 being opposite to that of arrow 91. The printing material layer 79 is transferred from the developing drum to the transfer drum 41 and then to the platform 51. A light beam 891 can also be configured to pass through the transfer drum 41-1 to illuminate the extruded printing material layer, thereby heat-pressing the layers together. If the printing material layer is a powdered resin material, the light beam 891 can be an infrared beam, radiating heat to melt the printing material layer, and utilizing the pressure of the transfer drum 41-1 to achieve bonding of the multiple layers. If the printing material layer is a photosensitive resin liquid material, the light beam 891 can be ultraviolet light or other light beams of a corresponding frequency that initiates photopolymerization, irradiating the extruded printing material layer to achieve bonding between the layers. A cleaner 14a and a cooler 821 can also be provided downstream of the point where the transfer drum 41-1 and the platform 51 meet to clean and cool the surface of the transfer drum 41-1 after the printed material layer has been laid, preparing for the subsequent transfer of the printed material layer. When the printing assembly moves to the left end, the platform 51 moves downward (relative longitudinal movement) a predetermined distance along arrow 94. Simultaneously, the second transfer drum 41-2 cooperates with the first transfer drum 41-1, transferring the printed material layer 79 from the first transfer drum 41-1 to the second transfer drum 41-2. The second transfer drum 41-2 rotates in the opposite direction of the first transfer drum 41-1. The printing assembly moves rightward along arrow 92, transferring the printed material layer 79 from the second transfer drum 41-2 to the platform 51. The light beam 891 can then be transmitted through the second transfer drum to illuminate the extruded printed material layer, achieving layer-by-layer bonding. Of course, a similar cleaner 14b and a cooler 822 can also be provided to clean and cool the surface of the second transfer drum after the printed material layer has been laid, preparing for the subsequent transfer of the printed material layer. When the printing assembly moves to the right end, the platform 51 moves down a preset distance, and then Figure 4a The printing material layer is laid onto the platform via the first conveyor drum, and this process is repeated until the model 71 is printed.

[0126] The first transfer drum 41-1 may include a first electrode 49-1 on the inner side and a thin insulating layer on the surface. The electric field formed by the appropriate voltage of the first electrode 49-1 is used to adsorb the printing material layer 79 on the developing drum onto the first transfer drum 41-1. The second transfer drum 41-2 may include a second electrode 49-2 on the inner side and a thin insulating layer on the surface. Figure 4bSecond electrode 49-2 is connected to an appropriate potential, forming a corresponding electric field with first electrode 49-1, attracting print material layer 79 from the surface of the first transfer drum to the surface of the second transfer drum, and then transporting it to the platform via the rotating second transfer drum. For example, if the print material layer has static electricity of a predetermined polarity (e.g., negative static electricity), first electrode 49-1 can be connected to a high-voltage power source with an opposite polarity (e.g., positive) or charged with static electricity of an opposite polarity (e.g., positive). The electrostatic field formed by first electrode 49-1 attracts print material layer 79 to the surface of the first transfer drum. If the electric field effect of the second electrode 49-2 on the printing material layer is weaker than that of the first electrode 49-1, the printing material layer 79 will still remain on the surface of the first transfer drum 41-1 and will be transferred to the platform through the rotating first transfer drum. If the second electrode 49-2 is connected to an electrode with a higher polarity (such as positive) or is charged with a higher polarity (such as positive), a higher electrostatic field will be formed to adsorb the printing material layer from the surface of the first transfer drum to the surface of the second transfer drum, and then be laid on the platform 51 through the second transfer drum. In this way, the transfer path of the printing material layer between the transfer drums or between the transfer drum and the developing drum can be easily controlled by controlling the potential of the electrodes in the corresponding transfer drums or controlling the potential of the electrostatic charge. Figure 4a The second conveying drum can also be moved away from the platform by a preset distance to avoid the friction between the second conveying drum and the model 71 affecting the printing accuracy. Figure 4b The second transfer drum 41-2 can move toward the platform 51, while the platform can simultaneously move downward a considerable distance, with a predetermined spacing between the two. However, a significant spacing can be maintained between the platform and the first transfer drum to prevent the first transfer drum from contacting the model 71 while the second transfer drum is laying down the print material, potentially affecting printing accuracy. The use of two transfer drums eliminates the need for the developer drum to directly participate in laying down the print material layer onto the platform, avoiding pressurization or heating of the developer drum and improving its reliability. Furthermore, during the reciprocating lateral relative motion of the printing assembly and the platform, the material is delivered to the platform via the identically structured transfer drum, facilitating consistent laying of the material in both the forward and reverse directions, improving printing accuracy, and facilitating equipment calibration and maintenance.

[0127] Figure 5 Indicates that you can also Figure 4a and Figure 4b On the basis of the illustrated embodiment, a plurality of developing assemblies are provided in the printing assembly. For example, a first developing assembly 10-1 and a second developing assembly 10-2 may be provided, each of whose developing drums cooperates with the first transfer drum 41-1 respectively, and respectively transfers the respectively formed printing material layers 79-1 and the printing material layers 79-2 to the surface of the first transfer drum according to a preset layer pattern. For example, the materials of the printing material layers 79-1 and 79-2 may be different, and heterogeneous printing material layers may be formed. For example, one of the materials may be a model material, and the other may be a temporary support material. Of course, both may be model materials to form a composite material model 71. Figure 4b The printed material layer is transported to the platform via the lower surface of the second transport drum 41-2. Figure 5 It is shown that the printing material layer can also be transferred to the platform via the upper surface of the second transfer drum 41-2. Figure 3 and Figure 5 It can be seen that the printing of composite material layers can be achieved by setting up multiple printing assemblies to lay printing material layers on the platform respectively. It is also possible to set up multiple developing assemblies on the same transmission medium to form a printing material layer of the composite material on this transmission medium and then transmit it to the platform.

[0128] Figure 6 illustrative embodiments and Figure 4a and 4b The difference is that heaters are installed outside the transfer drums and heat-pressing is used to lay the printing material layers onto the platform 51, achieving layer-by-layer bonding. For example, heater 813, located above the first transfer drum 41-1 and the second transfer drum 41-2, preheats the printing material layers so that when the printing material layers are laid and squeezed onto the platform by the first or second transfer drum, the appropriate temperature facilitates bonding between the layers. Coolers 821 and 822, respectively, cool the surfaces of the first and second transfer drums after the printing material layers have been laid, preparing for subsequent transfer of the printing material layers. Heaters 812 and 811 can be installed on the left and right sides of the printing assembly, respectively, to further heat the printing material layers laid onto the platform to strengthen the melting of the layers. Coolers 824 and 823, respectively, are located away from heaters 812 and 811, respectively, to dissipate heat from the model 71 and the molding surface, preparing for the laying of subsequent printing material layers.

[0129] Figure 7a and Figure 7b Another embodiment of a printing assembly is shown, Figure 4a and Figure 4b The difference from the illustrated solution is that the cooperation relationship between the second transfer drum 41 - 2 and the first transfer drum 41 - 1 and the developing drum 36 is adjustable, and the printing material layer 79 is ultimately laid on the platform 51 by the second transfer drum 41 - 2 . Figure 7a The second transfer drum 41-2 cooperates with the developing drum 36 driven clockwise, and the printing assembly moves leftward along the direction indicated by arrow 92 (set as the first stroke). The second transfer drum rotates counterclockwise along arrow 93. The printing material layer on the developing drum is transferred to the second transfer drum and then laid on the platform 51. After a layer of printing is completed, the printing assembly and the platform move longitudinally relative to each other by a preset distance. For example, the platform 51 moves down by a layer thickness distance, and the printing assembly moves in the opposite direction to the right (the second stroke). Figure 7bAs shown, at the same time, the second transfer drum 41-2 rotates clockwise along the arrow 93, and the second transfer drum can also move slightly to the left toward the first transfer drum, so that the second transfer drum 41-2 maintains a preset distance with the first transfer drum 41-1 and increases the distance with the developing drum, and the second transfer drum 41-2 cooperates with the first transfer drum 41-1, and the first transfer drum 41-1 cooperates with the developing drum 36, and the printing material layer 79 on the developing drum 36 is transferred to the first transfer drum 41-1, and then transferred to the second transfer drum 41-2, and finally laid on the platform 51 through the second transfer drum 41-2, and then the printing assembly and the platform move longitudinally relative to each other by a preset distance, for example, the platform 51 moves down by a layer thickness distance, and the printing assembly moves in the opposite direction to the left, as shown. Figure 7a As shown, the second transfer drum 41-2 can also be moved slightly to the right toward the developer drum 36, so that the second transfer drum 41-2 maintains a preset spacing with the developer drum 36 and increases the spacing with the first transfer drum 41-1. Of course, the platform can also be moved in the opposite direction indicated by arrow 92 relative to the printing assembly to perform printing. During the forward and reverse reciprocating movement of the printing assembly or platform, the same transfer drum, such as the second transfer drum, is used to lay the printing material onto the platform. This is more conducive to achieving consistency in the laying of the printing material layer during the reciprocating stroke, which helps improve printing accuracy. It also avoids the situation where the transfer drum or developer medium that originally transported the printing material layer in the second stroke (or first stroke) during the first stroke (or second stroke) and the platform easily come into contact with the solidified model 71 when multiple transfer drums or developer drums alternately transport the printing layer to the platform, thereby affecting printing accuracy.

[0130] The transmission medium in the above embodiment is a transmission drum, but of course a transmission belt can also be used. The printing assembly includes at least one developing assembly and at least one transmission belt. For example Figure 8a and Figure 8b The diagram shows two developing assemblies, namely the first developing assembly 10-1 and the second developing assembly 10-2, which are respectively matched with the conveyor belt 42. The conveyor belt 42 is supported by at least two rollers, which may include support rollers, transfer rollers or squeeze rollers according to their functions, for example Figure 8a Combine Figure 8b The multiple support rollers 46a, 46b and 46c are used to support the conveyor belt; the transfer rollers 45-1 and 45-2 can be used to control the transfer of the printing material layer from the developing drum to the conveyor belt. For example, the transfer rollers can be controlled to be electrically connected to a set voltage, and the presence or absence of an electric field on the transfer rollers or the intensity of the electric field can be adjusted to adjust the adsorption force on the printing material layer with static electricity, or the magnetic field on the transfer rollers can be adjusted to adjust the adsorption force on the printing material layer of magnetic materials; the squeezing roller 43 is used to lay and squeeze the printing material layer 79 onto the platform 51. The squeezing roller may also have a heating function to heat and pressurize the printing material layer onto the platform; the support roller 46c can be eliminated. Specifically, Figure 8aIn the embodiment, the transfer roller 45-1 and the transfer roller 45-2 are respectively close to the developing drums of the developing assembly 10-1 and the developing drums of the developing assembly 10-2. The transfer roller 45-1 and the transfer roller 45-2 have corresponding electrostatic fields, which adsorb the printing material layers 79-1 and 79-2 formed by the developing drums of the developing assembly 10-1 and the developing drums of the developing assembly 10-2 respectively onto the conveyor belt 42. The conveyor belt 42 can rotate repeatedly along the arrow 93, and the rotation direction of the conveyor belt 42 is opposite to the rotation direction of the developing drum. The printing material layer is transferred to the conveyor belt 42 by the transfer roller 45-1 and the transfer roller 45-2. The conveyor belt 42 is conveyed, and the platform 51 moves to the left along the arrow 92 shown in the figure. The extrusion roller 43 extrude and lay the conveyor belt and other printing material layers 79 onto the platform 51. For example, if the printing material layer is a powdered thermoplastic resin material, the extrusion roller 43 can also be heated appropriately to extrude the printing material layer with a raised temperature to achieve the combination between the layers, which is more conducive to forming the model 71. A cooler 823 can also be set to cool the surface of the conveyor belt after the printing material layer is laid, so as to prepare for the subsequent transmission of the printing material layer. The printing material layer laid on the platform can be further heated by the heater 812 to achieve complete fusion between the printing material layer and the model 71. After completing the printing of one layer of the left movement, the platform moves to the right, as shown in FIG. Figure 8b As shown, transfer rollers 45-1 and 45-2 are positioned away from the developer drums of the respective developer assemblies. Printing material layers 79-1 and 79-2 formed by the developer assemblies 10-1 and 10-2, respectively, are directly transferred by their respective developer drums and laid onto the platform 51. During the laying process, printing material layers 79-1 and 79-2 can be preheated and extruded, respectively. Coolers 821 and 822 can also be provided to cool the surfaces of the developer drums of the developer assemblies 10-1 and 10-2, respectively, where the printing material layers have been laid. The printing material layers laid onto the platform 51 can be further heated by heater 811 to allow the newly laid printing material layers to completely fuse and bond with the previously laid printing material layers.

[0131] Figure 9a and Figure 9b The schematic diagram shows that the printing assembly includes 2 developing assemblies and 2 conveyor belts. Figure 9a The printing material layer formed by the developing assembly 10-1 and the developing assembly 10-2 is transferred to the first conveyor belt 42-1. The first conveyor belt 42-1 rotates counterclockwise along the arrow 93, and the rotation direction is opposite to the rotation direction of the developing drum of the developing assembly. As the platform 51 below moves to the right relative to the printing assembly, the first conveyor belt 42-1 lays and squeezes the printing material layer from the squeezing rollers 43-1 and 43-2 to the platform 51. The transfer rollers 45-1 and 45-2 can be set to corresponding potentials to form an electric field, or set to corresponding magnetic fields to attract the printing material layer from the developing drum to the first conveyor belt 42-1. Then, the platform and the printing assembly move relative to each other longitudinally to increase the distance between them by a preset distance, and the platform moves in the opposite direction, as shown in FIG. Figure 9b, moving leftward along arrow 92. At the same time, the transfer roller 45-3 of the second conveyor belt 42-2 forms a corresponding potential or magnetic field, for example, a high electrostatic field is formed when it is connected to a high voltage power supply. Since the transfer roller 45-3 is arranged opposite to the first conveyor belt 42-1, the printing material layer 79 is adsorbed from the first conveyor belt 42-1 to the second conveyor belt 42-2. The second conveyor belt rotates clockwise along arrow 94, and the rotation direction is opposite to the rotation direction of the first conveyor belt 42-1. The second conveyor belt 42-2 lays and squeezes the printing material layer onto the platform 51 through the squeezing rollers 43-3 and 43-4. Figure 9a and Figure 9b The extrusion rollers 43-1 and 43-2, 43-3 and 43-4 can be heated to accelerate the bonding of the printing material layers. The extrusion rollers 43-1 and 43-2 can be combined into one extrusion roller, and the extrusion rollers 43-3 and 43-4 can be combined into one extrusion roller. In addition, the conveyor belt can also be light-transmissive. Figure 9a In the embodiment, a first light source 35-1 may be provided to emit a light beam through the first conveyor belt to illuminate the printed material layer in the extruded state. Figure 9b A second light source 35-2 can also be provided to emit a light beam through the second conveyor belt 42-2 to illuminate the extruded printing material layer, accelerating the bonding of the printing material layer with the printed material layer already laid on the platform through light curing or radiant heating. Coolers 821 and 822 cool the surfaces of the first and second conveyor belts, respectively, after the printed material layer has been laid. The functions of heaters 811 and 812 are the same as those described above and will not be repeated here. The support roller 46c can be combined with the transfer roller 45-1.

[0132] Figure 10a and 10b exist Figure 9a and 9b Based on the embodiment shown, the developing assemblies 10-1 and 10-2 can be transferred to the first conveyor belt 42-1 via the transfer drums 41-1 and 41-2, respectively. The first conveyor belt and the second conveyor belt each use a squeeze roller to lay the printing material layer in a heated and pressurized manner, and the structure is simplified. Figure 10b The middle driver 62-1 and the driver 62-2 respectively drive the developing drum of the first developing assembly 10-1 and the developing drum of the second developing assembly 10-2 to rotate in the first direction, and the driver 63-1 and the driver 63-2 respectively drive the first transfer drum and the second transfer drum to rotate in the second direction. The first direction and the second direction are opposite, for example, the first direction is counterclockwise and the second direction is clockwise. The driver 61-1 drives the first transfer belt 42-1 to rotate in the first direction by driving the support roller 46a, and the driver 61-2 drives the second transfer belt 42-2 to rotate in the second direction by driving the transfer roller 45-3. It can be seen that when the platform is composed of Figure 10a Move right to switch to Figure 10b In the reciprocating printing process shown in the figure, the developing drum, the transfer drum, the first transfer belt and the second transfer belt do not need to change the direction of rotation, which can greatly simplify the structure of the printing device, simplify the control and printing process, and help improve the reliability and stability of the device and improve printing efficiency. Figure 10a When the first squeezing roller 43-1 drives the first conveyor belt to squeeze and convey the printing material layer onto the platform 51, the second squeezing roller 43-2 can be slightly lifted away from the platform, so as to avoid the second conveyor belt 42-2 from contacting the model 71. Figure 10b During the first stroke of lateral movement between the platform and the printing assembly, the distance between the conveying medium or developer medium, which was originally used to lay the printing material layer during the second stroke, and the platform increases, for example, to a distance greater than the thickness of the printing material layer. Meanwhile, during the second stroke, the distance between the conveying medium or developer medium, which was originally used to lay the printing material layer during the first stroke, and the platform increases, for example, to a distance greater than the thickness of the printing material layer. This improves the stability and reliability of the printing process, and enhances the success rate and precision of printing.

[0133] Figure 11a and 11b Indicate in Figure 10a and Figure 10b On the basis of the scheme shown, the second conveyor belt 42-2 is replaced by the conveyor drum 41, or the conveyor drum 42-2 is cancelled. Figure 10a and 10b In the illustrated embodiment, the second conveyor belt and the transfer roller 45 - 3 , the conveyor drum 41 simultaneously functions as the squeeze roller 43 - 2 in FIG. 10 and also functions as the transfer roller 45 - 3 . Figure 11a In the figure, the printing material layer 79 is laid on the platform 51 by the first conveyor belt 42-1 rotating in the first direction. The conveyor drum 41 rotates in the second direction and disconnects the corresponding voltage (not shown in the figure), or cancels the corresponding electrostatic field or magnetic field, so that the printing material layer 79 will not be attracted to the conveyor drum 41. After the printing of this stroke (for example, the first stroke) is completed, the platform moves in the reverse direction to print the reverse stroke, such as Figure 11bThe first conveyor belt 42-1 continues to rotate in the first direction, and the conveyor drum 41 continues to rotate in the second direction. The conveyor drum 41 can generate an electrostatic field or a magnetic field. For example, the conveyor drum 41 is electrically connected to a corresponding voltage. The printing material layer 79 is first transferred from the conveyor belt 42-1 to the conveyor drum 41, and then laid by the conveyor drum 41 onto the platform 51. Because the diameter of the conveyor drum 41 can be relatively small, the distance between the transfer point of the printing material layer from the first conveyor belt to the conveyor drum 41 (the printing material layer output position of the conveyor belt 42-1 and the printing material layer receiving position of the conveyor drum 41) and the platform is shortened, which is more conducive to the rapid switching of the printing material layer during the reciprocating motion of the platform, and further helps to further improve the printing speed. Figures 8a to 11b The developing assembly or developing drum in each embodiment may be one or more.

[0134] Figure 12a and Figure 12b The schematic printing assembly includes a first developing assembly 10-1 and a first transfer drum 41-1 cooperating therewith, a second developing assembly 10-2 and a second transfer drum 41-2 cooperating therewith, and also includes a conveyor belt 42 that can cooperate with the first developing assembly 10-1 and the second developing assembly 10-2, or with the first transfer drum 41-1 and the second transfer drum 41-2, respectively, and the two cooperation relationships can be dynamically adjusted. Figure 12a In the embodiment, the transfer roller 45-1 and the transfer roller 45-3 move upward, and the distance between them and the first transfer drum 41-1 and the second transfer drum 41-2 is a preset value (≥0, and may also be 0, that is, contact). The first printing material layer 79-1 is transported by the first developing assembly and the first transfer drum and adsorbed onto the conveyor belt 42. The second printing material layer 79-2 is transported by the second developing assembly and the second transfer drum and adsorbed onto the conveyor belt 42 to form a printing material layer 79. It is assumed that the developing drum of the developing assembly rotates along the first direction (such as counterclockwise rotation), the first transfer drum and the second transfer drum rotate along the second direction (such as clockwise rotation), the conveyor belt 42 rotates along the first direction, and the lower platform 51 moves to the right (such as the first stroke), and the squeezing roller 43 lays the printing material layer 79 on the platform 51. A heater 813 can be provided on the left side of the conveyor belt 42 to preheat the printing material layer 79, a cooler 821 can be provided on the right side of the conveyor belt 42 to dissipate heat from the conveyor belt surface on which the printing material layer is laid, and a heater 811 can be provided on the right side of the conveyor belt to further heat the printing material layer laid on the platform 51. After the first stroke of printing is completed, the platform moves to the left to print the second stroke. Figure 12b As shown, the second stroke is opposite to the first stroke. At the same time, the transfer rollers 45-1 and 45-3 move downwards away from the first conveying drum and the second conveying drum respectively, and the transfer rollers 45-2 and 45-4 move upwards close to the first developing assembly and the second developing assembly respectively, with a preset distance (≥0) between them and their developing drums. The rotation direction of the conveyor belt 42 is adjusted to rotate in the second direction, that is, Figure 12bAs indicated by the middle arrow 93, each roller of the conveyor belt 42 simultaneously adjusts its rotational direction accordingly. The printing material layer is transferred to the conveyor belt 42 by the developer assembly and then laid onto the leftward movable platform 51 via the right side of the conveyor belt by the squeeze roller 43. A heater 812 on the right side of the conveyor belt preheats the printing material layer, while a cooler 822 on the left side cools the conveyor belt surface after the printing material layer is laid. A heater 814 on the left side of the conveyor belt further heats the printing material layer laid onto the platform belt. As shown in the figure, a pressure roller 44 can also be provided above the conveyor belt to cooperate with a corresponding transfer roller. When the transfer roller moves away from the developer drum or transfer drum, the pressure roller presses the conveyor belt downward to move it away from the developer drum or transfer drum. The developer drum and transfer drum can also use separate transfer drums to transfer the printing material layer to the conveyor belt, and the rotational direction of the developer drum or conveyor belt needs to be adjusted accordingly.

[0135] Figure 13a and 13b The diagram shows that conveyor belts can also be installed on both the upper and lower sides of the developing assembly. In the figure, the first conveyor belt 42-1 and the second conveyor belt 42-2 are respectively installed below and above the developing assembly 10-1 and the developing assembly 10-2. A third conveyor belt 42-3 is also provided to cooperate with the second conveyor belt 42-2, and of course, it can also cooperate with the first conveyor belt 42-1. Transfer rollers 45-3 and 45-4 are respectively installed on the inner side of the second conveyor belt 42-2, corresponding to the developing assembly 10-1 and the developing assembly 10-2. Transfer rollers 45-1 and 45-2 are respectively installed on the inner side of the first conveyor belt 42-1, corresponding to the developing assembly 10-1 and the developing assembly 10-2. Figure 13a The middle transfer roller 45-3 and the transfer roller 45-4 respectively push the second conveyor belt close to the developing assembly 10-1 and the developing assembly 10-2 and maintain a preset distance (≥0). The printing material layer formed by the developing assembly 10-1 and the developing assembly 10-2 is transferred to the second conveyor belt. It is assumed that the developing drums of the developing assembly 10-1 and the developing assembly 10-2 rotate along the first direction (such as clockwise), and the second conveyor belt rotates along the second direction (such as counterclockwise) to drive the printing material layer to rotate. When it reaches the transfer roller 45-5 of the third conveyor belt 42-3, it is adsorbed on the third conveyor belt 42-3. The third conveyor belt rotates along the first direction to lay the printing material layer on the platform 51 moving downward to the left. The squeezing roller 43-2 drives the third conveyor belt to squeeze the printing material layer toward the platform to complete a layer of printing. The platform moves down a layer thickness and moves in the opposite direction to the right (such as the first stroke). Figure 13b, at the same time, the second conveyor belt and the third conveyor belt can stop rotating, and the printing material layer thereon can be maintained. The transfer roller 45-3 and the transfer roller 45-4 are respectively away from the developing assembly 10-1 and the developing assembly 10-2, and the second conveyor belt is synchronously away from the developing assembly 10-1 and the developing assembly 10-2 (such as under the action of its own elasticity). The transfer roller 45-1 and the transfer roller 45-2 respectively push the first conveyor belt to move closer to the developing assembly 10-1 and the developing assembly 10-2 to a preset distance (≥0). The first conveyor belt rotates along the second direction, and the printing material layers of the developing assembly 10-1 and the developing assembly 10-2 are respectively transferred to the first conveyor belt, and are laid on the platform 51 by the first conveyor belt. The squeezing roller 43-1 drives the first conveyor belt to squeeze the printing material layer toward the platform to complete a layer of printing. The platform moves down a layer thickness and then moves to the left (such as the first stroke). The first conveyor belt rotates in the second direction, and the printing material layers of the developing assembly 10-1 and the developing assembly 10-2 are respectively transferred to the first conveyor belt. The first conveyor belt is laid on the platform 51, and the squeezing roller 43-1 drives the first conveyor belt to squeeze the printing material layer toward the platform. After a layer of printing is completed, the platform moves down a layer thickness and then moves to the left (such as the first stroke). The conveyor belt can stop rotating, and the printing material layer thereon is maintained, and the transfer roller 45-1 and the transfer roller 45-2 are respectively away from the developing assembly 10-1 and the developing assembly 10-2, and the first conveyor belt is synchronously away from the developing assembly 10-1 and 10-2 (such as under the action of its own elasticity), and the transfer roller 45-3 and the transfer roller 45-4 respectively push the second conveyor belt to move closer to the developing assembly 10-1 and the developing assembly 10-2 to a preset distance (including 0, that is, contact). When the platform moves to the left, the printing material layer previously maintained on the second conveyor belt and the third conveyor belt can be directly laid onto the platform. There is no need to wait for the printing material layer formed by the developing assembly to be transferred via the second conveyor belt and the third conveyor belt before starting to print a new printing layer, which can greatly improve printing efficiency. Figure 13a The process is repeated. Cooler 821 and cooler 822 cool the surfaces of the first conveyor belt and the third conveyor belt after the printing material layer is laid.

[0136] Figure 14 The plan is Figure 13a and Figure 13b On the basis of , the second conveyor belt and the third conveyor belt are combined into one conveyor belt, that is Figure 14 The second conveyor belt 42-2 in the development assembly 10-1 and the development assembly 10-2 are respectively matched with the first conveyor drum 41-1 and the second conveyor drum 41-2, the first conveyor drum 41-1 and the second conveyor drum 41-2 are matched with the second conveyor belt 42-2, and the transfer roller 45-3 and the transfer roller 45-4 correspond to the first conveyor drum 41-1 and the second conveyor drum 41-2 respectively. Figure 13aDuring the printing process, the platform shifts to the left, the developing drum of the developing assembly rotates in a first direction, the first and second conveyor drums rotate in a second direction, and the second conveyor belt rotates in the first direction. The first direction is clockwise (or counterclockwise), and the second direction is counterclockwise (or clockwise). The printing material layers formed by the developing assembly 10-1 and the developing assembly 10-2 are transferred to the second conveyor belt 42-2 via the first and second conveyor drums, respectively. The two printing material layers can be laid on the same layer. The composite printing material layer 79 (composite printing material layer) formed by matching the material information at different positions in the layer is laid onto the platform 51 by the second conveyor belt 42-2. This can reduce the number of conveyor belts, replacing them with conveyor drums, which is more conducive to improving the accuracy of the transfer and transmission of the printing material layers and simplifying the structure of the device.

[0137] Figure 15 exist Figure 14 On the basis of the embodiment, an extrusion roller is added to the first conveyor belt 42-1 and the second conveyor belt 42-2 respectively, the extrusion roller 43-1 and the extrusion roller 43-2 correspond to the platform in the first conveyor belt 42-1, and the extrusion roller 43-3 and the extrusion roller 43-4 correspond to the platform in the second conveyor belt 42-2. In this way, the parts of the first conveyor belt and the second conveyor belt corresponding to the platform are formed into flat parts, and the light beams emitted by the first light source 35-1 and the second light source 35-2 can be respectively transmitted through the first conveyor belt and the second conveyor belt to irradiate the printing material layer, thereby accelerating the curing and bonding speed of the printing material layer.

[0138] Figure 16a and Figure 16b It is shown that a second conveyor belt 42-2 and a first conveyor belt 42-1 can be respectively provided on the left and right sides of the developing assembly, which is equivalent to Figure 15 In this solution, the two developing assemblies are arranged vertically instead of horizontally, with the second and first conveyor belts positioned vertically on either side of the developing assembly. This structure allows for symmetrical arrangement of the conveyor belts on either side of the developing assembly, ensuring that the print material layer travels the same or similar distances on both the first and second conveyor belts. This results in more symmetrical printing during the first and second reciprocating strokes, further simplifying the device and reducing the number of components. It also enhances consistency in printing during the relative reciprocating strokes. Figure 16aIt shows that the printing assembly moves to the right along the arrow 92 (such as the second stroke), and the printing material layers of the developing assembly 10-1 and the developing assembly 10-2 are respectively transferred to the second conveyor belt 42-2 on the left through the transfer drum 41-1 and the transfer drum 41-2, and are laid on the platform 51 below by the second conveyor belt. At the same time, a light beam 89 can be set to illuminate the printing material layer being laid through the second conveyor belt 42-2. The developing drum of the developing assembly is rotated in a first direction (such as clockwise), the transfer drum 41-1 and the transfer drum 41-2 are rotated in a second direction (such as counterclockwise), and the second conveyor belt rotates in the first direction. Figure 16b The first developing assembly 10-1 and the second developing assembly 10-2 are shown as being coupled to the first conveyor belt on the right side. The first conveyor belt 42-1 rotates in the second direction and moves leftward with the printing assembly (e.g., the first stroke) to deposit the printing material layer onto the platform 51. Simultaneously, a light beam 89 can penetrate the first conveyor belt 42-1 and illuminate the deposited printing material layer, allowing the deposited printing material layer to combine with the previously deposited printing material layer. Specifically, if the printing material layer is a photosensitive resin liquid, the light beam 89 can be a light beam for photopolymerization. If the printing material layer is a thermoplastic resin powder, the light beam 89 can be infrared light. Figure 16a As shown in the figure, when the second conveyor belt moves to the right with the printing assembly and lays the printing material layer, the first conveyor belt on the right can be appropriately raised away from the platform to more reliably avoid contact with the model 71 on the platform. Figure 16b As shown in the figure, when the first conveyor belt moves to the left with the printing assembly while laying the printing material layer, the second conveyor belt on the left does not need to be raised away from the platform, because there is a gap of the thickness of the printing layer between the second conveyor belt and the model 71. As long as the movement accuracy is sufficient, it can avoid contact with the model 71 on the platform. Figure 16a The first conveyor belt in the printing process may not need to be moved up. This can simplify the control process of the device and printing.

[0139] Figure 8a In the various embodiments of FIG. 16 , the printing assembly can also move in a direction opposite to that indicated by arrow 92, instead of the platform 51 moving along arrow 92. Platform 51 can also be positioned above the printing assembly. The printing assembly can include only one developing assembly, or it can include more. Using a conveyor belt as the transmission medium makes it easier to flexibly control the transfer and switching of printing material layers and the placement of printing material layers on the platform by arranging transfer rollers and squeezing rollers. The conveyor belt can be made of a variety of elastic film materials, such as DuPont's "KAPTON."

[0140] Figure 17a and Figure 17bThe schematic printing assembly includes two developing assemblies and two transfer drums. The developing drum 36-1 of the first developing assembly 10-1 on the left cooperates with the first transfer drum 41-1 on the left and rotates in opposite directions to each other. The developing drum 36-2 of the second developing assembly 10-2 on the right cooperates with the second transfer drum 41-2 on the right and rotates in opposite directions to each other. The first transfer drum 41-1 cooperates with the second transfer drum 41-2, and the developing drum 36-1 of the first developing assembly and the developing drum 36-2 of the second developing assembly rotate in opposite directions. If the developing drum 36-1 of the first developing assembly rotates in the first direction, for example, counterclockwise along the arrow 91a, the developing drum 36-2 of the second developing assembly rotates in the second direction, for example, clockwise along the arrow 91b, the first transfer drum rotates in the second direction, such as along the arrow 93a, and the second transfer drum rotates in the first direction, such as along the arrow 93b. Figure 17a The printing assembly moves rightward along arrow 92 (i.e., the first stroke of the lateral relative movement), and the first printing material layer 79-1 formed by the first developing assembly 10-1 is transferred to the first transfer drum 41-1. The second printing material layer 79-2 formed by the second developing assembly 10-2 is transferred to the second transfer drum 41-2. The second printing material layer 79-2 is transferred from the second transfer drum 41-2 to the first transfer drum 41-1. For example, the surface layers of the first transfer drum and the second transfer drum are respectively thin insulating layers, and the interiors are respectively conductive layers and are connected to corresponding electrodes, and the first transfer drum can be made of a conductive layer. The potential of the electrode connected to the conductive layer is higher than the potential of the electrode connected to the conductive layer of the second transfer drum. In this way, the first transfer drum 41-1 can absorb the first printing material layer, and at the same time, it can also absorb the second printing material layer from the surface of the second transfer drum, forming a composite material printing material layer 79 (composite printing material layer) on the first transfer drum 41-1 and laying it on the platform 51 below by the first transfer drum 41-1. There is a layer thickness gap between the second transfer drum on the right and the molding surface of the platform (the upper surface of the model 71 shown in the figure), so the second transfer drum will not contact the model 71 during the printing process. When the printing assembly moves to the right end and completes a layer of printing, the platform 51 drops a preset distance, such as the layer thickness distance, which means that the longitudinal relative movement of the printing assembly and the platform is completed, and then the printing assembly moves to the left (such as the second stroke of the horizontal relative movement), as shown. Figure 17bAs shown, at the same time, the first printing material layer 79-1 is transferred to the second transfer drum 41-2 via the first transfer drum 41-1. For example, the potential of the electrode connected to the conductive layer of the second transfer drum can be adjusted to be higher than the potential of the electrode connected to the conductive layer of the first transfer drum. The first printing material layer 79-1 and the second printing material layer 79-2 form a composite printing material layer 79 (composite printing material layer) and are laid onto the platform 51 by the second transfer drum 41-2. There is a layer thickness gap between the first transfer drum on the left and the molding surface of the platform (the upper surface of the model 71 shown in the figure), so the first developing drum will not contact the model 71 during the printing process. When the printing assembly moves to the left end and completes a layer of printing, the platform moves down a preset distance, and then the printing assembly moves to the right again, and as shown Figure 17a The printing material layer 79 is laid out on the platform 51 by the first transfer drum, and this process is repeated until the model 71 is printed. During the reciprocating lateral movement of the entire printing assembly relative to the platform, the various rotation directions of the first developing assembly 10-1, the first transfer drum 41-1, the second developing assembly 10-2, and the second transfer drum 41-2 remain unchanged, and printing is possible during the reciprocating stroke. At the same time, two developing assemblies can print simultaneously, for example, to form a model 71 of multiple materials. During the entire printing process, the first transfer drum and the second transfer drum are alternately shared by the first printing material layer 79-1 and the second printing material layer 79-2, further improving the utilization rate of the transmission medium and the printing efficiency of the device. The materials of the first printing material layer 79-1 and the second printing material layer 79-2 can be different or the same. The layers of printed material laid onto the platform can be bonded and solidified in a variety of ways. For example, light beams 89-1 or 89-2 can be used to illuminate the layers of printed material being laid onto the platform through the first or second conveyor drum, respectively. In this case, both the surface insulation layer and the internal conductive layer of the first or second conveyor drum can be made of light-transmitting materials. Coolers 821 and 822, respectively, dissipate heat from the surfaces of the first and second conveyor drums, where the layers of printed material have been laid, preparing for the transfer and laying of subsequent layers of printed material. Alternatively, a heater or heating function can be used to heat the first and second layers of printed material, allowing the melted layers of printed material to be heat-pressed onto the forming surface of the platform 51 by the first or second conveyor drum.

[0141] Figure 18 exist Figure 17a and Figure 17bOn the basis of the above, the first and second transfer drums are eliminated, and the first developing drum 36-1 of the first developing assembly and the second developing drum 36-2 of the second developing assembly are arranged in conjunction with each other. For example, when the printing assembly moves rightward as shown in the figure, which corresponds to the first stroke of lateral relative movement of the printing assembly and the platform, the printing material layer 79-2 formed by the second developing drum 36-2 is transferred to the first developing drum 36-1. For example, the electrostatic field strength charged by the first charger 13-1 associated with the first developing drum on the first developing drum 36-1 can be greater than the electrostatic field strength charged by the second charger 13-2 associated with the second developing drum on the second developing drum 36-2. The second printing material layer charged with static electricity is attracted by the second developing drum 36-2 to the first developing drum 36-1. The printing material layer 79-2 transferred to the first developing drum 36-1 and the printing material layer 79-1 on the first developing drum 36-1 can be stacked to form a composite printing material layer 79, and laid by the first developing drum 36-1 onto the platform 51 below. The second developing drum on the right side has a gap of one or two layer thicknesses with the molding surface of the platform (the upper surface of the model 71 shown in the figure), so the second developing drum will not contact the model 71 during the printing process. After a layer of printing is completed, the platform and the print assembly move longitudinally relative to each other, for example, by moving the platform downward by a predetermined distance (e.g., the layer thickness). The print assembly then moves leftward, for example, equivalent to a second stroke of lateral relative movement between the print assembly and the platform. Print material layer 79-1 on the left first developer drum is transferred to the right second developer drum. For example, the electrostatic field strength charged by the second charger 13-2 associated with the second developer drum on the second developer drum 36-2 can be greater than the electrostatic field strength charged by the first charger 13-1 associated with the first developer drum on the first developer drum 36-1. The first statically charged print material layer is attracted by the first developer drum 36-1 to the second developer drum 36-2. Print material layer 79-1 and print material layer 79-2 form a composite print material layer 79 on the second developer drum. The second developer drum then lays down print material layer 79 on the lower platform 51. A gap of one or two layer thicknesses exists between the left first developer drum and the mold 71, preventing contact with the mold 71. In this embodiment, both developing drums also function as transfer drums. For example, the first developing drum 36-1 in the figure serves as a transfer drum for the second developing drum 36-2. When the printing assembly moves leftward, the printing material layer on the first developing drum 36-1 is transferred to the second developing drum 36-2 and then laid on the platform. Therefore, the second developing drum also serves as a transfer drum for the first developing drum. This reduces the number of parts and allows for a more compact structure.Of course, a first electrode 49-1 can also be provided on the inner side of the first developing drum 36-1, and a second electrode 49-2 can be provided on the inner side of the second developing drum 36-2. During a first stroke of lateral relative movement of the printing assembly and the platform, the electric field strength of the first electrode 49-1 is set to be higher than that of the second electrode 49-2. Then, the printing material layer 79-2 formed on the second developing drum 36-2 is transferred to the first developing drum 36-1, forming a single-layer composite printing material layer 79 with the printing material layer 79-1 formed on the first developing drum 36-1. During a second stroke of lateral relative movement of the printing assembly and the platform, the electric field strength of the second electrode 49-2 is set to be higher than that of the first electrode 49-1. Then, the printing material layer 79-1 formed on the first developing drum 36-1 is transferred to the second developing drum 36-2, forming a single-layer composite printing material layer 79 with the printing material layer 79-2 formed on the second developing drum 36-2. The materials of the printing material layers 79-1 and 79-2 can be the same or different.

[0142] Figure 19a and Figure 19b Indicate in Figure 17a and Figure 17b On the basis of the above, a third transfer drum 41-3 is provided between the first transfer drum 41-1 and the second transfer drum 41-2. The first developing drum 36-1 is provided to rotate in a first direction (e.g., counterclockwise) and the second developing drum 36-2 is provided to rotate in a second direction (e.g., clockwise). The cooperation relationship between the third transfer drum 41-3 and the first and second transfer drums can be dynamically adjusted. The lower cross-sections of the first and second transfer drums can be coplanar and parallel to the platform 51 below. The lower cross-section of the third transfer drum can be lower than the lower cross-sections of the first and second transfer drums by a preset distance, such as the thickness of the layer, for example. Figure 19a The printing assembly moves to the right relative to the platform, and the third transfer drum cooperates with the second transfer drum and rotates in the second direction. The printing material layer 79-2 formed by the second developing drum 36-2 is transferred to the second transfer drum, and then transferred to the third transfer drum, and then laid on the platform by the third transfer drum; at the same time, the printing material layer 79-1 formed by the first developing drum 36-1 is transferred to the first transfer drum 41-1 and then laid on the platform, for example, stacked and laid on the printing material layer 79-2 as shown in the figure. In this way, two layers of printing material are laid at the same time, which can greatly improve the printing speed. After completing one layer of printing, the platform moves down a preset distance, such as the thickness of two layers, and the printing assembly is adjusted to move to the left, such as Figure 19bAs shown, the third transfer drum adjusts its rotation direction to the first direction and cancels its coordination with the second transfer drum. Instead, it coordinates with the first transfer drum. The printing material layer 79-1 formed by the first developing drum is transferred to the first transfer drum and then to the third transfer drum. The third transfer drum lays it on the platform. The printing material layer 79-2 formed by the second developing drum is transferred to the second transfer drum and laid on the platform. For example, it is stacked and laid on the printing material layer 79-1 as shown in the figure. In this way, two layers of printing material are laid simultaneously, which can greatly improve the printing speed. The platform then descends by a preset distance, such as a distance of two layer thicknesses, and the printing assembly is adjusted to move to the right, as shown in FIG. Figure 19a In the state shown, the third transfer drum adjusts its direction and cooperates with the second transfer drum, and this process is repeated back and forth until the model 71 is printed. If the lower section of the third transfer drum is made coplanar with the lower section of the first transfer drum or the second transfer drum, the printing material layer laid by the third transfer drum can also be laid on the same layer as the printing material layer laid by the first transfer drum or the second transfer drum, so that a printing material layer composed of multiple materials can be realized. It can be seen that the third transfer drum 41-3 is alternately reused by the first printing material layer 79-1 and the second printing material layer 79-2. The figure also illustrates the curing method when the printing material layer is laid on the platform, for example Figure 19a The middle light beam 89-3 passes through the third transfer drum 41-3 to illuminate the printing material layer 79-2, and the light beam 89-1 passes through the first transfer drum 41-1 to illuminate the printing material layer 79-1. Figure 19b The middle light beam 89-3 passes through the third transfer drum 41-3 to illuminate the printed material layer 79-1, and the light beam 89-2 passes through the first transfer drum 41-1 to illuminate the printed material layer 79-2. Furthermore, the figure also illustrates a method for transferring the printed material layer from the first transfer drum or the second transfer drum to the third transfer drum, and uses electrostatic imaging technology as an example to illustrate that a charger 13c is provided in the upper area of ​​the third transfer drum, a charge eliminator 15c-1 is provided in the lower area near the first transfer drum and the platform, and a charge eliminator 15c-2 is provided in the lower area near the second transfer drum and the platform, for example, Figure 19a In the process, the charger 13c charges the surface of the third conveyor drum with high-voltage static electricity, causing the printing material layer 79-2 to be attracted from the surface of the second conveyor drum to the surface of the third conveyor drum. At the same time, the eliminator 15c-1 eliminates static electricity on the surface of the third conveyor drum where the printing material layer has been laid, so that the surface area of ​​the third conveyor drum close to the first conveyor drum is free of static electricity and will not attract the printing material layer 79-1 on the surface of the first conveyor drum. Similarly, in Figure 19bDuring the process, charger 13c applies high-voltage static electricity to the surface of the third transfer drum, causing print material layer 79-1 to be attracted from the first transfer drum to the third transfer drum. Simultaneously, charge eliminator 15c-2 eliminates static electricity on the surface of the third transfer drum where the print material layer has been deposited, leaving the surface area of ​​the third transfer drum near the second transfer drum free of static electricity and preventing it from attracting print material layer 79-2 from the second transfer drum. Overall, charger 13c, located on the third transfer drum's surface relatively far from the platform, applies high-intensity static electricity to the third transfer drum. As the third transfer drum rotates, the first or second print material layer is attracted to the third transfer drum's surface downstream near the first or second transfer drum. As the third transfer drum rotates toward the platform, it is pressed and deposited onto the platform. Then, as the third transfer drum continues to rotate, the charge eliminator located downstream eliminates static electricity on the third transfer drum's surface, preventing the third transfer drum from adsorbing the second or first print material layer on the second or first transfer drum. The charge eliminator between the third transfer drum and the platform near the first or second transfer drum ceases operation.

[0143] Figure 20 exist Figure 19a and Figure 19b In the illustrated embodiment, the third conveyor drum 41-3 is replaced with a conveyor belt 42, supported and rotated by a first transfer roller 45-1, a second transfer roller 45-2, and a squeeze roller 43. The first transfer roller 45-1 is coupled to the first conveyor drum via the conveyor belt 42, while the second transfer roller 45-2 is coupled to the second conveyor drum via the conveyor belt 42. The squeeze roller 43 is used to lay and squeeze the printing material layer conveyed on the conveyor belt onto the platform. For example, in the figure, when the printing assembly moves rightward, the conveyor belt 42 rotates in the second direction. The second transfer roller can be connected to a high-potential electrode or generate a high magnetic field to attract the second printing material layer 79-2 on the second conveyor drum onto the conveyor belt 42. The second printing material layer 79-2 is then transferred from the conveyor belt to the squeeze roller and laid onto the platform below. Simultaneously, the first printing material layer 79-1 is laid by the first conveyor drum onto the platform below. As shown in the figure, the first printing material layer 79-1 and the second printing material layer 79-2 can be laid on the same layer, for example, to form a composite material model of multiple materials. After a layer of printing is completed, the platform is lowered by a predetermined distance, such as the layer thickness, and the printing assembly is then moved to the left. Simultaneously, the conveyor belt is adjusted to rotate in the first direction, the electrostatic field or magnetic field of the second transfer drum 45-2 is reduced or eliminated, and the electrostatic field or magnetic field of the first transfer roller 45-1 is increased. The first printing material layer 79-1 is attracted by the first transfer drum 41-1 onto the conveyor belt 42 and laid onto the platform. The second printing material layer is then laid onto the platform by the second transfer drum. The use of the conveyor belt 42 allows for more convenient control of the electric field or magnetic field between the first and second transfer rollers to achieve the desired transfer of printing material layers.

[0144] Figure 21a and Figure 21b Indicate in Figure 19a and 19b Based on this solution, the first conveyor drum 41-1, the second conveyor drum 41-2, and the third conveyor drum 41-3 are replaced with the first conveyor belt 42-1, the second conveyor belt 42-2, and the third conveyor belt 42-3, respectively. The third conveyor belt can be alternately coupled with the first and second conveyor belts. The first conveyor belt 42-1 and the second conveyor belt 42-2 rotate in opposite directions, while the third conveyor belt rotates in the opposite direction to the conveyor belts it is cooperating with. Furthermore, more developing assemblies can be provided to cooperate with the first and second conveyor belts, respectively. Each developing assembly can also cooperate with the first or second conveyor belt via a conveyor drum. For example, the developing assemblies 10-1 and 10-2 cooperate with the first conveyor belt through the conveying drum 41a-1 and the conveying drum 41a-2 respectively, and the developing assemblies 10-3 and the developing assemblies 10-4 cooperate with the second conveyor belt through the conveying drum 41a-3 and the conveying drum 41a-4 respectively. In this way, the first printing material layer 79-1 formed on the first conveyor belt and the first printing material layer 79-2 formed on the second conveyor belt can be multi-material (heterogeneous) printing material layers respectively. Figure 21a In the example, assume the platform moves rightward. The first printing material layer 79-1 is transferred via the first conveyor belt 42-1 to the third conveyor belt 42-3, and then to the platform below. For example, the transfer roller 45 of the third conveyor belt can slightly lean toward the first conveyor belt to absorb the printing material layer. The second printing material layer 79-2 is transferred by the second conveyor belt 42-2 to the platform below and stacked with the first printing material layer 79-1. This allows for simultaneous printing of two layers of heterogeneous materials. The platform then moves downward by a predetermined distance, such as a layer thickness of two layers, and moves leftward. Simultaneously, the third conveyor belt changes its rotational direction and can move slightly closer to the second conveyor belt via the transfer roller 45 to coordinate with the second conveyor belt. The second printing material from the second conveyor belt is absorbed by the third conveyor belt and laid onto the platform. Simultaneously, the first conveyor belt lays the first printing material layer onto the platform, where it is stacked on the second printing material layer. The functions of other components with the same numbering are the same as described above and are not repeated here.

[0145] Figure 22 Indicate Figure 21a and Figure 21b The transfer roller 45 of the third conveyor belt is replaced by two, namely transfer roller 45-1 and transfer roller 45-2, which cooperate with the first conveyor belt and the second conveyor belt respectively, similar to Figure 20 In the solution shown, the transfer switching control of the printing material layer can be achieved by simply controlling the precise electrostatic field or magnetic field of the transfer rollers 45 - 1 and 45 - 2 . Figures 21a to 22 The illustrated solution implements a multi-material and multi-layer printing process simultaneously, which can achieve faster printing of the multi-material model 71.

[0146] from Figure 19a-Figure 22 It can be seen that the third transmission medium (such as Figure 19a and 19b The third transfer drum 41-3 in Figure 20 Conveyor belt 42, Figures 21a to 22 The distance between the third conveyor belt 42-3 in the embodiment and the platform 51 can be greater than that between the first conveyor belt 42-3 and the platform 51. Figures 19a to 20 The first transfer drum 41-1, Figures 21a to 22 The first conveyor belt 42-1) or the second conveyor medium (such as Figures 19a to 20 The second transfer drum 41-2, Figures 21a to 22 The distance between the second conveyor belt 42-2 and the platform 51 can be less than one printing material layer thickness, allowing two layers of printing material to be laid simultaneously on the platform. The distance between the third conveyor medium and the platform can also be equal to the distance between the first conveyor medium or the second conveyor medium and the platform, allowing multiple materials to be laid simultaneously on the same layer on the platform. Of course, the distance between the third conveyor medium and the platform 51 can also be less than the distance between the first conveyor medium or the second conveyor medium and the platform 51 by multiple printing material layer thicknesses, allowing more layers of printing material to be laid simultaneously on the platform. For example, multiple developing assemblies can be used in conjunction with the first conveyor medium or the second conveyor medium to form stacked printing material layers on the first conveyor medium or the second conveyor medium. This can further increase printing speed. Figure 23a and Figure 23b exist Figure 17a and Figure 17b Based on this solution, the first transfer drum 41-1 and the second transfer drum 41-2 are replaced with a first conveyor belt 42-1 and a second conveyor belt 42-2, respectively. The first conveyor belt is supported by a first transfer roller 45-1 and a first squeeze roller 43-1, while the second conveyor belt is supported by a second transfer roller 45-2 and a second squeeze roller 43-2. ​​By setting an appropriate potential or magnetic field on the first transfer roller 45-1 and the second transfer roller 45-2, the printing material layer formed by the first developing assembly 10-1 can be attracted to the first conveyor belt, and the printing material layer formed by the second developing assembly 10-2 can be attracted to the second conveyor belt, respectively. Figure 23a The printing assembly moves to the right, and the second printing material layer 79-2 on the second conveyor belt on the right is adsorbed onto the first conveyor belt on the left. For example, the potential or magnetic field of the first squeezing roller 43-1 can be higher than that of the second pressure roller 43-2. ​​The first printing material layer and the second printing material layer are laid by the first conveyor belt and the first squeezing roller onto the platform below. After one layer of printing is completed, the platform 51 moves down a preset distance, such as the layer thickness. Of course, the printing assembly can also move up a preset distance. This can be done in all embodiments of the present invention. Figure 23b, the printing assembly moves to the left, and the printing material layer 79-1 on the first conveyor belt is adsorbed onto the second conveyor belt. For example, the potential or magnetic field of the second squeezing roller 43-2 can be made higher than that of the first squeezing roller 43-1. The first and second printing material layers are laid on the platform by the first conveyor belt and the first squeezing roller. Then the platform moves down or the printing assembly moves up a preset distance, and returns to Figure 23a The process repeats itself. In this embodiment, the first squeeze roller 43-1 and the second squeeze roller 43-2 also function as transfer rollers to control the transfer of the printed material layer. The first squeeze roller 43-1 and the second squeeze roller 43-2 can also be heated to increase the temperature of the printed material layer for easier placement on the platform. Coolers 822 and 824, respectively, cool the surfaces of the first and second conveyor belts after the printed material layer is laid or transferred.

[0147] Figure 24 Yes Figure 23a and Figure 23b The illustrated embodiment has been modified by adding a third transfer roller 45-3 and a fourth transfer roller 45-4 to the first and second conveyor belts, respectively, to attract the printing material layers from the first and second developing assemblies 10-1 and 10-2 to the first and second conveyor belts, respectively. This allows the first and second transfer rollers 45-1 and 45-2 to control the transfer of the printing material layers between the first and second conveyor belts. The first and second squeeze rollers do not need to also function as transfer rollers. Support rollers 46b and 46c can be used to tension the first and second conveyor belts, respectively, and facilitate quick adjustment of the conveyor belt's movement direction after the printing material layer is laid, facilitating separation of the printing material layer from the conveyor belts. Figures 23a to 24 Furthermore, in the illustrated embodiment, the first conveyor belt can be used in conjunction with a plurality of developing assemblies, and the second conveyor belt can be used in conjunction with a plurality of developing assemblies.

[0148] Figure 25a and Figure 25bThe developing medium of the illustrated developing assembly is a developing belt. The developing assembly 10 includes a developing belt 38, a developing engine, and a feeder. The developing engine is used to form an electrostatic latent image or a magnetic latent image on the developing belt 38. For example, the developing engine may include a charger 13 and a developing light source 31 arranged in sequence along the rotation direction of the developing belt 38, with the feeder 2 positioned downstream of the developing light source 31. The developing belt 38 rotates in a first direction, such as the clockwise direction of arrow 91, and the conveyor belt 42 rotates in a second direction, such as the counterclockwise direction of arrow 93. The developing belt is provided with a corresponding transfer roller 45 of the conveyor belt 42 via a supporting roller 46c, so that the conveyor belt 42 cooperates with the developing belt 38. The developing belt 38 may include an outer photoconductive layer 11 and an inner conductive layer 12. The charger 13 forms static electricity on the developing belt. The developing light source 31 selectively irradiates the developing belt. The irradiated area is conductive so that the static electricity is released by the conductive layer and electrically connected to an electrode with a preset potential, forming an electrostatic latent image on the surface of the developing belt. The feeder 2 conveys the printing material to the developing belt, and the printing material layer 79 with the corresponding pattern is formed by the electrostatic latent image. When Figure 25a As shown, the lower platform 51 moves rightward along arrow 92, i.e., the second stroke of the lateral relative movement of the platform and the printing assembly. The printing material layer 79 on the left side of the developing belt is transferred to the conveyor belt 42. For example, the transfer roller 45 is connected to a high-voltage power supply to form a strong electric field to attract the printing material layer to the conveyor belt 42, and the conveyor belt 42 lays it on the lower platform 51. After completing a layer of printing, the platform and the printing assembly move longitudinally relative to each other, such as the platform 51 moves down a preset distance, or the printing assembly moves up a preset distance, and then the platform moves to the left, i.e., the first stroke of the lateral relative movement of the platform and the printing assembly, as shown. Figure 25b The printing material layer 79 is laid directly from the developing belt 38 onto the platform 51 below. For example, the transfer roller 45 can be disconnected from the high-potential power source, eliminating the electrostatic field. This prevents the statically charged printing material layer 79 from being attracted to the conveyor belt 42 when passing through the area of ​​the conveyor belt 42 near the transfer roller 45. By controlling whether the transfer roller is connected to the high-potential power source or the voltage level at which it is connected, the direction of the printing material layer can be switched. Coolers 821 and 822 can cool the surfaces of the developing belt and conveyor belt, respectively, after the printing material layer has been laid. Figure 25a It is also shown in the figure that when the conveyor belt lays the printing material layer on the platform, the squeezing roller 43-1 of the developing belt can also move slightly away from the platform to better avoid contact with the model 71 on the platform. Figure 25b When the developing belt lays the printing material layer onto the platform, the squeezing roller 43-2 of the conveyor belt can also move slightly away from the platform, which can better avoid contact with the model 71 on the platform and improve the stability of the printing process.

[0149] Figure 26 Indicate in Figure 25a or Figure 25bOn the basis of the embodiment, the conveyor belt 42 is replaced with a second developing belt, which, together with the second developing engine and the second feeder, forms a second developing assembly. The transfer roller 45-2 of the second developing belt is arranged corresponding to the transfer roller 45-1 of the first developing belt, and the first and second developing belts rotate in opposite directions. In addition, the developing engines in this embodiment can also be ion (or charge) injectors. For example, the first developing engine includes a first ion (or charge) injector 34-1 and an upstream charge eliminator 15-1, and the second developing engine includes a second ion (or charge) injector 34-2 and an upstream charge eliminator 15-2. When the platform below moves to the right (such as the first stroke), the first developing belt 38-1 on the left rotates clockwise, and the printing material layer thereon is transferred to the second developing belt 38-2 on the right that rotates counterclockwise. For example, the transfer roller 45-2 on the second developing belt is connected to a high-potential power supply to form a strong electric field or an electromagnet is used to pass a larger current to form a strong magnetic field, and the first transfer roller can be disconnected from the high-potential power supply. When the first developing belt drives the printing material layer 79-1 to rotate near the transfer roller 45-2, it is adsorbed onto the second developing belt and forms a composite printing material layer 79 with the second printing material layer 79-2 on the second developing belt. The material layer 79 is conveyed by the squeezing roller 43-2 of the second developing belt and laid on the platform 51. After completing one layer of printing, the platform moves down a preset distance and moves to the left (such as the first stroke), so that the transfer roller 45-1 of the first developing belt can be connected to the high-potential power supply to form a strong electric field or magnetic field, and the second transfer roller can be disconnected from the high-potential power supply. The second developing belt drives the printing material layer 79-2 to rotate near the transfer roller 45-1 and be adsorbed onto the first developing belt, and form a composite printing material layer 79 on the first developing belt with the first printing material layer 79-1 on the first developing belt. The printing material layer 79 is conveyed by the squeezing roller 43-1 of the first developing belt and laid on the platform 51. The aforementioned composite means that the printing material layer 79 is formed by multiple printing material layers, and is not limited to the printing material layer containing multiple materials. It can also be a single material. For example, the first printing material layer 79-1 and the second printing material layer 79-2 are stacked and combined on the second developing belt 45-2 or the first developing belt 45-1 to form a composite printing material layer 79 (composite printing material layer). The composite printing material layer is formed by stacking multiple printing material layers on the developing medium or the conveying medium. Compared with the aforementioned developing drum solution, the use of the developing belt makes it easier to flexibly control the transfer and switching of the printing material layers and the laying of the printing material layers on the platform by arranging transfer rollers and squeezing rollers, as well as the arrangement of heaters and coolers. It can also reduce the number of conveyor belts or transfer drums used or even eliminate them, simplifying the structure.

[0150] The printing material layer 79 can be a photosensitive resin liquid, a thermoplastic resin powder, a mixture of a photosensitive resin liquid and other powders, or a mixed powder formed by multiple powder materials, such as a mixture of ceramic powder and thermoplastic resin powder. Alternatively, the printing material layer 79 can be an iron powder material or a magnetic powder material, or a mixture of an iron powder material or a magnetic powder material with a resin powder material. The corresponding developing assembly can use magnetic imaging technology for imaging.

[0151] The developing assembly can form a printing material layer using the following method, including a latent image forming process and a developing process. Specifically,

[0152] Step 1: forming a latent image.

[0153] For xerograph-based imaging, the development engine includes a charger 13 and a development light source 31. The latent image formation process includes 1) a charging process and 2) an exposure and imaging process. Specifically, during the charging process, the photosensitive development drum rotates in a first direction while a charger applies a negative (or positive) charge to the drum surface. The charger can be a corona wire, corotron, scorotron, charging roller, or other charging methods. During the exposure and imaging process, the development light source selectively illuminates the drum surface while the drum rotates. The photoconductive layer of the drum is made of a photoconductive material and has a high resistivity when not exposed to light. When illuminated, the resistivity decreases significantly, allowing the charge there to be discharged through the conductive layer. This area is then electrically connected to an electrode at a preset potential. The charge in the unexposed areas remains unchanged, forming an electrostatic latent image on the drum surface. The development light source can be a laser beam, an LED (light emitting diode), or other light source that can selectively control the illumination point to form a dot matrix pattern on the drum surface. The photoconductive layer uses a photoconductive material such as an organic photoconductive material (photoconductive polymer), such as polyvinyl carbazole, or other photoconductive materials. It can also form a micro-nano array of photoelectric materials, or it can be an inorganic photoconductive material. The photoconductive material can also be made of selenium, cadmium sulfide, zinc oxide, amorphous silicon or zinc oxide, etc. The photoconductive material changes its resistivity when exposed to light according to the photoconductive effect (or photoconductive effect). If the conductive layer is transparent, it can be made of indium tin oxide, aluminum-doped zinc oxide or other transparent and conductive materials. Ion injection (ionography) can also be used. This can be regarded as a special form of electrostatic imaging technology. The development engine uses an ion injector. Steps 1) charging process and 2) exposure imaging process can be combined into one step, that is, ion injection is selectively performed on the surface of the development drum to directly form an electrostatic latent image. In this method, the conductive layer of the development drum can be eliminated, and the charger can be eliminated.

[0154] Magnetography technology can also be used. The developing engine is an imaging head, and the developing drum can be a magnetic drum. The surface layer of the developing drum 36 is made of a magnetic material layer. The magnetic state of each point on the surface of the magnetic material layer is selectively changed according to the layer pattern information of the three-dimensional model. For example, recording points are formed by establishing an array of magnetized areas in the magnetic material layer on the surface of the developing drum. This process can also be understood as selectively exposing the surface of the magnetic drum. The selective exposure forms these recording points to form a latent magnetic image, that is, a latent magnetic image. By using magnetic imaging technology, the surface layer of the magnetic drum has high hardness and a longer life, and the magnetic recording points have a permanent memory function, that is, the latent magnetic image formed by the magnetic recording points can be reused periodically.

[0155] Step 2, the development process, is the process of forming an actual image from an electrostatic latent image in electrostatic imaging technology. This process is accomplished by utilizing the principle that like charges repel and opposite charges attract. When the surface portion of the developing drum bearing the latent image is rotated to the feeder, the printed material conveyed by the feeder is selectively adsorbed to the developing drum surface based on the latent image. For example, the feeder applies negative (or positive) static electricity to the printed material layer, causing the negatively (or positively) charged printed material on the feeder to jump to the latent image area of ​​the developing drum. For example, the dark areas (unexposed areas) on the developing drum still carry a negative (or positive) charge, which repels the negatively (or positively) charged printed material and prevents it from adhering. This forms a visible image formed by the printed material layer on the developing drum, forming a visible pattern. It should be noted that the electrostatic latent image can be formed by the decharged portion of the developing drum, or the uncharged portion of the developing drum can be used to form the electrostatic latent image to attract the printed material layer to form the developed image. The process based on this imaging technology is similar. Using magnetography, the latent magnetic image on the developing drum (magnetic drum) rotates to the feeder, selectively attracting the printing material to form a printing material layer. The magnetic printing material (which can be magnetized) in the feeder is selectively attracted to the surface of the developing drum based on the latent magnetic image, forming a printing material layer and a visible pattern. In some embodiments, a demagnetizer can be provided to restore the magnetic state of the surface layer of the magnetic drum to its initial state after the printing material layer is laid or transferred. This process is then repeated as the developing drum rotates periodically until the model is printed.

[0156] The developing drum in the above steps may also be a developing belt.

[0157] The printing material layer formed by the developing assembly can be laid on the platform through a transfer process, and stacked and laid layer by layer to form a model, that is, the printing material layer is laid on the platform 51 directly by the developing drum or indirectly by the transfer process, and can also be reinforced by heating, light polymerization or pressurization. During this process, the printing assembly and the platform move relative to each other laterally. After each stroke (first stroke or second stroke) of printing is completed, the printing assembly and the platform move relative to each other longitudinally to increase the distance between the two to achieve layer by layer stacking of the printing material layers. In some embodiments, a cleaning process or a static removal process or a demagnetization process can also be included. The cleaner cleans the residual printing material that has not been completely transferred from the developing drum surface so that there is a clean developing drum surface in the next printing cycle. The developing drum cleaner can use a scraper, a brush or a cleaning roller, or utilize vacuum cleaning, or a combination of the above-mentioned cleaning methods for cleaning.

[0158] The directional terms "upper," "lower," "left," and "right" used in the description of the present invention are for convenience in describing the specific drawings and are not intended to limit the present invention. In practice, due to spatial transformations of the overall structure, the actual orientation may differ from that in the drawings. However, such transformations are within the scope of protection claimed by the present invention.

Claims

1. A three-dimensional printing device comprising a printing assembly and a platform capable of relative movement, characterized in that: The printing assembly includes: at least one developing assembly and a conveying unit; The developing assembly comprises: The developing medium rotates in a fixed direction; a developing engine for forming a latent image on a developing surface of the developing medium; A material feeder, used for providing printing material to the latent image to form a printing material layer; The conveying unit includes at least one conveying medium, which is used to adjust the matching relationship between the conveying medium and the developing medium, and / or adjust the matching relationship between the conveying medium to change the number of times the printing material layer is transferred from the developing medium to the platform, so that the printing material layer can be conveyed to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

2. The three-dimensional printing device according to claim 1, characterized in that: The conveying unit includes a conveying medium; the conveying medium is a conveying drum or a conveying belt, and the developing medium of the developing assembly is a developing drum or a developing belt; the conveying medium and the developing medium are arranged in coordination; during a first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer on the developing medium is directly conveyed to the platform by the developing medium; During the second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer on the developing medium is transferred from the developing medium to the conveying medium rotating in the opposite direction to the developing medium, and then the conveying medium conveys the printing material layer to the platform; or, The conveying unit includes a conveying medium, which is a conveyor belt; the printing assembly includes multiple developing assemblies, the developing media of the developing assemblies are developing drums or developing belts, and the rotation directions are the same; the conveying medium is arranged in conjunction with each developing medium; during the first stroke of the horizontal relative movement of the printing assembly and the platform, the printing material layer on each developing medium is directly conveyed to the platform by each developing medium; during the second stroke of the horizontal relative movement of the printing assembly and the platform, the printing material layer on each developing medium is respectively transferred from the corresponding developing medium to the conveying medium in the opposite rotation direction of the developing medium to form a composite printing material layer, and then the composite printing material layer is conveyed to the platform by the conveying medium.

3. The three-dimensional printing device according to claim 1, characterized in that: The conveying unit includes a first conveying medium and a second conveying medium. A preset distance is maintained between the first conveying medium and the developing medium, and the first conveying medium rotates in opposite directions. By adjusting the matching relationship between the second conveying medium and the first conveying medium, during a first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the first conveying medium. During a second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the first conveying medium and the transfer of the second conveying medium rotating in the opposite direction to the first conveying medium in sequence. Or, The conveying unit includes a first conveying medium and a second conveying medium. By adjusting the matching relationship between the first conveying medium and the developing medium, and / or the matching relationship between the second conveying medium, the developing medium, and the first conveying medium, during a first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is transferred from the developing medium to the second conveying medium in a direction opposite to the rotation direction of the developing medium, and is conveyed to the platform by the second conveying medium. During a second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the first conveying medium in a direction opposite to the rotation direction of the developing medium and the second conveying medium in a direction opposite to the rotation direction of the first conveying medium in sequence. Alternatively, The conveying unit includes a first conveying medium and a second conveying medium, wherein the first conveying medium is a conveyor belt, and the second conveying medium is a conveyor drum or a conveyor belt; the printing assembly includes a plurality of developing assemblies, wherein the developing media of the developing assemblies are developing drums or developing belts, and the developing media rotate in the same direction; each of the developing media maintains a preset distance from the first conveying medium and rotates in the opposite direction to the first conveying medium; by adjusting the matching relationship between the second conveying medium and the first conveying medium, during a first stroke of relative lateral movement of the printing assembly and the platform, the printing material layers formed by each of the developing media are transferred from the corresponding developing medium to the first conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the first conveying medium; during a second stroke of relative lateral movement of the printing assembly and the platform, the printing material layers formed by each of the developing media are transferred from the corresponding developing medium to the first conveying medium to form a composite printing material layer, and the composite printing material layer is conveyed to the platform by the transfer of the first conveying medium via the second conveying medium that rotates in the opposite direction to the first conveying medium.

4. The three-dimensional printing device according to claim 1, characterized in that: The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium. The developing medium and the first conveying medium maintain a preset distance and rotate in opposite directions. The first conveying medium and the second conveying medium maintain a preset distance and rotate in opposite directions. By adjusting the matching relationship between the third conveying medium and the second conveying medium, the printing material layer is conveyed from the developing medium to the platform through the transfer of the first conveying medium and the transfer of the second conveying medium with a rotation direction opposite to that of the second conveying medium, or the printing material layer is conveyed to the platform through the transfer of the first conveying medium, the second conveying medium, and the third conveying medium; or The conveying unit includes a first conveying medium, a second conveying medium and a plurality of third conveying media, each of the third conveying media is a conveying drum, the first conveying medium is a conveying belt, and the second conveying medium is a conveying drum or a conveying belt; the printing assembly includes a plurality of developing assemblies, and the rotation direction of the developing medium of each developing assembly is the same; each of the developing media maintains a preset distance with the corresponding third conveying medium, and the rotation directions are opposite; each of the third conveying media maintains a preset distance with the first conveying medium and rotates in the opposite direction of the first conveying medium, by adjusting the matching relationship between the second conveying medium and the first conveying medium, when the printing assembly and the platform move relative to each other in the horizontal direction of the first row During the first stroke, the printing material layers respectively formed by each developing assembly are respectively transferred from the corresponding developing medium to the first transmission medium through the corresponding third transmission medium to form a composite printing material layer, and the composite printing material layer is transferred to the platform by the first transmission medium; during the second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layers respectively formed by each developing assembly are respectively transferred from the corresponding developing medium to the first transmission medium through the corresponding third transmission medium to form a composite printing material layer, and the composite printing material layer is transferred from the first transmission medium to the platform through the second transmission medium that rotates in the opposite direction to the first transmission medium; or The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium, wherein the first conveying medium and the second conveying medium are respectively arranged in cooperation with different positions of the developer medium; the third conveying medium is arranged in cooperation with the first conveying medium, and by adjusting the cooperation relationship between the first conveying medium and the developer medium, and / or the cooperation relationship between the second conveying medium and the developer medium, during the second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developer medium to the platform through the transfer of the first conveying medium in a direction opposite to the rotation direction of the developer medium and the transfer of the third conveying medium in a direction opposite to the rotation direction of the first conveying medium, and during the first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developer medium to the platform through the transfer of the second conveying medium in a direction opposite to the rotation direction of the developer medium; or, The conveying unit includes a first conveying medium, a second conveying medium, and a third conveying medium. The first conveying medium and the second conveying medium are respectively arranged on both sides of the developing assembly. By adjusting the matching relationship between the first conveying medium and the developing medium, the matching relationship between the second conveying medium and the third conveying medium, and / or the matching relationship between the third conveying medium and the developing medium, during a first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the first conveying medium in a direction opposite to the rotation direction of the developing medium. During a second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer is conveyed from the developing medium to the platform via the transfer of the third conveying medium in a direction opposite to the rotation direction of the developing medium and the transfer of the second conveying medium in a direction opposite to the rotation direction of the third conveying medium in sequence; or The conveying unit includes a second conveying medium, a third conveying medium, and a plurality of first conveying media, wherein the first conveying media are conveying drums, and the second conveying medium and the third conveying medium are conveying belts. The plurality of developing assemblies' developing media are respectively arranged in cooperation with the corresponding first conveying medium, and the second conveying medium and the third conveying medium are respectively arranged on both sides of the plurality of developing assemblies and the first conveying medium. By adjusting the cooperation relationship between the second conveying medium and the first conveying medium, and / or the cooperation relationship between the third conveying medium and the developing medium, during a second stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer respectively formed by each developing assembly is conveyed from the corresponding developing medium to the platform through transfer by the first conveying medium in a direction opposite to the rotation of the developing medium and transfer by the second conveying medium in a direction opposite to the rotation of the first conveying medium. During the first stroke of the lateral relative movement of the printing assembly and the platform, the printing material layer respectively formed by each developing assembly is conveyed from the corresponding developing medium to the platform through transfer by the third conveying medium in a direction opposite to the rotation of the developing medium; or The conveying unit includes a second conveying medium, a third conveying medium and a plurality of first conveying media, wherein the plurality of first conveying media are conveying drums, the second conveying medium and the third conveying medium are conveying belts, the plurality of developing assemblies are arranged vertically, the developing medium of each developing assembly is respectively matched with the corresponding first conveying medium, the second conveying medium and the third conveying medium are respectively arranged on both sides of the plurality of developing assemblies and the corresponding first conveying media, each first conveying medium is matched with the second conveying medium, and each developing medium is matched with the third conveying medium, by adjusting the second conveying medium and the first conveying medium The matching relationship between the medium and / or the matching relationship between the third transmission medium and the developing medium, when the printing assembly and the platform move relative to each other in the second stroke, the printing material layer formed by each developing assembly is transferred from the corresponding developing medium through the corresponding first transmission medium opposite to the rotation direction of the developing medium and the second transmission medium opposite to the rotation direction of the first transmission medium to the platform, when the printing assembly and the platform move relative to each other in the first stroke, the printing material layer formed by each developing assembly is transferred from the corresponding developing medium through the third transmission medium opposite to the rotation direction of the developing medium to the platform.

5. The three-dimensional printing device according to any one of claims 1 to 4, characterized in that: Adjusting the coordination relationship between the transmission medium and the developing medium specifically includes: adjusting the adsorption force of the transmission medium on the printing material layer and / or adjusting the distance between the transmission medium and the developing medium; adjusting the coordination relationship between the transmission media specifically includes: adjusting the adsorption force of the transmission medium on the printing material layer and / or adjusting the distance between the transmission media.

6. The three-dimensional printing device according to claim 5, characterized in that: The matching relationship between the transmission medium and the developing medium or another transmission medium is adjusted in one of the following ways: Method 1: The printing material layer has static electricity, and a conductive layer or electrode is provided inside the transmission medium. The voltage or potential of the conductive layer or electrode is adjusted to adjust the electric field strength near the transmission medium to adjust the adsorption force of the transmission medium on the printing material layer on the developer medium or other transmission medium; Method 2: The printing material layer has static electricity, the outer surface of the transmission medium is an insulating layer, and a charger and a dissipator are provided on the outer side of the transmission medium to adjust the static electricity on the surface of the transmission medium and thereby adjust the adsorption force of the transmission medium on the printing material layer on the developer medium or other transmission medium; Method three, the printing material layer is a magnetic material powder, and a magnetic field control device is provided to adjust the magnetism and magnetic field strength of the surface of the transmission medium to adjust the adsorption force of the transmission medium on the printing material layer on the developing medium or other transmission medium; In a fourth embodiment, the conveying unit further includes a position adjustment mechanism, wherein the position adjustment mechanism is used to adjust the distance between the conveying medium and the developing medium, the distance between the conveying medium and other conveying media, or the distance between the conveying medium and the platform; Mode 5, the conveying medium is a conveying drum, and the conveying unit further includes a swing mechanism, the swing mechanism being used to control the swing of the conveying drum to adjust the distance between the conveying drum, the developing medium or other conveying medium and the platform; Method six, the transmission medium is a conveyor belt, and the transmission unit further includes a transfer roller; adjusting the distance between the conveyor belt and the developing medium or other transmission medium, adjusting the voltage of the transfer roller, or adjusting the magnetic field strength of the transfer roller.

7. The three-dimensional printing device according to claim 1, characterized in that: In the first stroke of the lateral relative movement of the platform and the printing assembly, the distance between the transmission medium or the developing medium that originally transported the printing material layer to the platform in the second stroke and the platform increases, and the increase value is greater than the thickness of the printing material layer. In the second stroke of the lateral relative movement of the platform and the printing assembly, the distance between the transmission medium or the developing medium that originally transported the printing material layer to the platform in the first stroke and the platform increases, and the increase value is greater than the thickness of the printing material layer.

8. The three-dimensional printing device according to claim 1, characterized in that: A cleaner and / or a cooler are also provided downstream of the output position of the printing material layer of the conveying medium or the developing medium. The cleaner is used to clean the surface of the conveying medium or the developing medium, and the cooler is used to dissipate heat from the surface of the conveying medium or the developing medium.

9. The three-dimensional printing device according to claim 1, characterized in that: The printing material layer transferred to the platform is cured and bonded to the platform or the solidified model on the platform in one of the following ways: way one, the printing material layer is a heat-fusible powder material, and the printing material layer is heated and extruded by the transmission medium or the developer medium and hot-pressed onto the platform or the solidified model on the platform; way two, the printing material layer is a heat-fusible powder material, and a heating light beam is irradiated toward the platform through the transmission medium or the developer medium to heat the printing material layer in the extruded state, and the printing material layer is hot-pressed onto the platform or the solidified model on the platform; way three, the printing material layer is a heat-fusible powder material, and a heater heats the printing material layer. The printing material layer is heated to melt, and the developing medium or the conveying medium pressurizes the printing material layer toward the platform so that the printing material layer is combined with the platform or the solidified model on the platform; a fourth method is that the printing material layer is a photosensitive resin liquid material that can be polymerized by light or a slurry material mixed with a photosensitive resin liquid and a powder material, and a curing light beam is transmitted through the conveying medium or the developing medium to irradiate the printing material layer toward the platform, and the printing material layer is polymerized and solidified to be combined with the platform or the solidified model on the platform; a fifth method is that the conveying medium is a conveyor belt, and the conveying unit further includes an extrusion roller; the extrusion roller is used to extrude the printing material layer onto the platform or the solidified model on the platform.

10. A three-dimensional printing method, using the three-dimensional printing device according to claim 1, characterized in that: During the printing process, When the printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the matching relationship between the transmission medium and the developing medium, and / or adjusting the matching relationship between the transmission medium, so that the printing material layer generated by the developing assembly is transferred to the platform after N times of transfer; When the printing assembly and the platform perform a second stroke of lateral relative movement, the conveying unit adjusts the conveying medium and the developing medium, and / or adjusts the matching relationship between the conveying media, so that the printing material layer generated by the developing assembly is transferred to the platform after N+1 transfers; The printing material layers transferred to the platform are solidified to achieve layer-to-layer bonding, and multiple layers of the printing material layers are stacked and bonded to form a final solidified model; Wherein, N is a natural number.

11. A three-dimensional printing device comprising a printing assembly and a platform capable of relative movement, characterized in that: The printing assembly includes: a first developing assembly, a second developing assembly and a conveying unit; The first developing assembly includes A first developing medium rotates in a first fixed direction; a first developing engine for forming a first latent image on a developing surface of the first developing medium; a first material feeder, configured to provide printing material to the first latent image to form a first printing material layer; The second developing assembly includes: a second developing medium, rotating in a second fixed direction; a second developing engine for forming a second latent image on a developing surface of the second developing medium; a second material feeder, configured to provide printing material to the second latent image to form a second printing material layer; The first fixing direction is opposite to the second fixing direction; The conveying unit includes a first conveying medium and a second conveying medium, wherein a preset distance is maintained between the first conveying medium and the first developing medium, and the rotation directions are opposite; a preset distance is maintained between the second conveying medium and the second developing medium, and the rotation directions are opposite; the conveying unit adjusts the matching relationship between the first conveying medium and the second conveying medium to change the number of transfers of the first printing material layer from the first developing medium to the platform and the number of transfers of the second printing material layer from the second developing medium to the platform, so that the first printing material layer and the second printing material layer can be conveyed to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

12. The three-dimensional printing device according to claim 11, characterized in that: The first transmission medium is a first transmission drum, and the second transmission medium is a second transmission drum. The transmission unit adjusts the matching relationship between the first transmission medium and the second transmission medium specifically by: adjusting the adsorption force of the first transmission drum and the second transmission drum on the first printing material layer and the second printing material layer so that the adsorption force of the first transmission drum is greater than the adsorption force of the second transmission drum, so that the first printing material layer is transferred from the first developing medium through the first transmission drum to the platform, and the second printing material layer is transferred from the second developing medium through the second transmission drum to the platform; or making the adsorption force of the second transmission drum greater than the adsorption force of the first transmission drum so that the first printing material layer is transferred from the first developing medium through the first transmission drum and the second transmission drum to the platform, and the second printing material layer is transferred from the second developing medium through the second transmission drum to the platform; or The first transmission medium is a first conveyor belt, and the second transmission medium is a second conveyor belt. The first conveyor belt is arranged in cooperation with the first developing medium and has opposite rotation directions. The second conveyor belt is arranged in cooperation with the second developing medium and has opposite rotation directions. The rotation directions of the first conveyor belt and the second conveyor belt are opposite; the first conveyor belt is equipped with a first transfer roller, a third transfer roller and a first squeezing roller, and the second conveyor belt is equipped with a second transfer roller, a fourth transfer roller and a second squeezing roller. The third transfer roller maintains a preset distance from the first developing medium and has opposite rotation directions, and is used to absorb the first printing material layer to the first conveyor belt; the fourth transfer roller maintains a preset distance from the second developing medium and has opposite rotation directions, and is used to absorb the printing material layer to the second conveyor belt; the first transfer roller and the second transfer roller maintain a preset distance from the second developing medium and have opposite rotation directions, and are used to absorb the printing material layer to the second conveyor belt. The transfer rollers are arranged relative to each other and rotate in opposite directions; the conveying unit adjusts the matching relationship between the first conveying medium and the second conveying medium specifically by: adjusting the adsorption force of the first transfer roller to be greater than the adsorption force of the second transfer roller, so that the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt, and the second printing material layer is transferred to the platform through the transfer of the second conveyor belt and the transfer of the first conveyor belt in sequence, or adjusting the adsorption force of the second transfer roller to be greater than the adsorption force of the first transfer roller, so that the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt and the transfer of the second conveyor belt in sequence, and the second printing material layer is transferred from the second developing medium to the platform through the transfer of the second conveyor belt; or The first transmission medium is a first conveyor belt, and the second transmission medium is a second conveyor belt. The first conveyor belt is equipped with a first transfer roller and a first squeezing roller, and the second conveyor belt is equipped with a second transfer roller and a second squeezing roller. The first transfer roller maintains a preset distance from the first developing medium and rotates in opposite directions, and is used to absorb the first printing material layer to the first conveyor belt; the second transfer roller maintains a preset distance from the second developing medium and rotates in opposite directions, and is used to absorb the second printing material layer to the second conveyor belt; the first squeezing roller and the second squeezing roller are also used to adjust the adsorption force on the first printing material layer and the second printing material layer; the conveying unit adjusts the first transmission medium. The coordination relationship between the conveying medium and the second conveying medium is specifically as follows: adjusting the adsorption force of the first squeezing roller and the second squeezing roller on the first printing material layer and the second printing material layer so that the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt, and the second printing material layer is transferred to the platform in sequence through the transfer of the second conveyor belt and the transfer of the first conveyor belt, or the first printing material layer is transferred from the first developing medium to the platform through the transfer of the first conveyor belt and the transfer of the second conveyor belt in sequence, and the second printing material layer is transferred from the second developing medium to the platform through the transfer of the second conveyor belt.

13. The three-dimensional printing device according to claim 11 or 12, characterized in that: The conveying unit also includes a third conveying medium, which is located between the first conveying medium and the second conveying medium. The conveying unit adjusts the matching relationship between the third conveying medium and the first conveying medium and the second conveying medium so that the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveying medium, and the second printing material layer is conveyed from the second developing medium to the platform through the transfer of the second conveying medium and the transfer of the third conveying medium in the opposite direction of rotation of the second conveying medium, or the first printing material layer is conveyed from the first developing medium to the platform through the transfer of the first conveying medium and the transfer of the third conveying medium in the opposite direction of rotation of the first conveying medium, and the second printing material layer is conveyed from the second developing medium to the platform through the transfer of the second conveying medium.

14. The three-dimensional printing device according to claim 13, characterized in that: The coordination relationship between the third transmission medium, the first transmission medium and the second transmission medium is adjusted as follows: adjusting the distance between the third transmission medium and the first transmission medium and the second transmission medium; or, Adjusting the adsorption force of the first transmission medium and the third transmission medium on the first printing material layer, and the adsorption force of the second transmission medium and the third transmission medium on the second printing material layer; or The third conveying medium is a third conveying drum, and a charger is arranged on the surface of the third conveying drum in a direction relatively away from the platform to charge the surface of the third conveying drum with static electricity. As the third conveying drum rotates, the first printing material layer or the second printing material layer is adsorbed onto the surface of the third conveying drum at a position close to the first conveying medium or the second conveying medium in the downstream direction of the rotation. As the third conveying drum rotates to the platform, the first printing material layer or the second printing material layer is extruded and laid onto the platform. Then, as the third conveying drum continues to rotate, the static electricity on the surface of the third conveying drum is eliminated by a charger at a downstream position; or The third transmission medium is a third transmission belt, and the third transmission belt is equipped with a transfer roller and a squeeze roller, and the distance between the transfer roller and the first transmission medium and the second transmission medium is adjusted, and / or the adsorption force of the transfer roller on the printing material layer on the side close to the first transmission medium and the side close to the second transmission medium is adjusted; or The third transmission medium is a third conveyor belt, and the third conveyor belt is equipped with a first transfer roller, a second transfer roller and an extrusion roller. The first transfer roller is set in conjunction with the first transmission medium, and the second transfer roller is set in conjunction with the second transmission medium. The adsorption force of the first transfer roller and the second transfer roller on the first printing material layer and the second printing material layer are adjusted respectively.

15. The three-dimensional printing device according to claim 13, characterized in that: The distance between the third transmission medium and the platform is smaller than the distance between the first transmission medium or the second transmission medium and the platform by one or more printing material layers; or, the distance between the third transmission medium and the platform is equal to the distance between the first transmission medium or the second transmission medium and the platform.

16. A three-dimensional printing method, using the three-dimensional printing device according to claim 11, characterized in that: During the printing process, when the printing assembly and the platform perform a first stroke of lateral relative movement, the matching relationship between the first transmission medium and the second transmission medium is adjusted so that the first printing material layer is transferred to the platform after N transfers, and the second printing material layer is transferred to the platform after N+1 transfers; when the printing assembly and the platform perform a second stroke of lateral relative movement, the matching relationship between the first transmission medium and the second transmission medium is adjusted so that the first printing material layer is transferred to the platform after N+1 transfers, and the second printing material layer is transferred to the platform after N transfers; wherein N is a natural number.

17. A three-dimensional printing method according to claim 16, characterized in that: During the printing process, the first printing material layer is transferred to the first transmission medium, and the second printing material layer is transferred to the second transmission medium; The printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the matching relationship between the first transmission medium and the second transmission medium so that the second printing material layer is transferred from the second transmission medium to the first transmission medium, the first printing material and the second printing material form a composite printing material layer on the first transmission medium, and the composite printing material layer is transported to the platform by the first transmission medium; The printing assembly and the platform move longitudinally relative to each other and are separated by a preset distance; The printing assembly and the platform perform a second stroke of lateral relative movement, adjusting the matching relationship between the first transmission medium and the second transmission medium so that the first printing material layer is transferred from the first transmission medium to the second transmission medium, the first printing material and the second printing material form a composite printing material layer on the second transmission medium, and the composite printing material layer is transported to the platform by the second transmission medium; The printing assembly and the platform move longitudinally relative to each other and are separated by a preset distance; The above process is repeated, and the printing material layers transferred to the platform are solidified to achieve layer-to-layer bonding, and multiple layers of the printing material layers are stacked and bonded to form a final solidified model.

18. A three-dimensional printing device comprising a printing assembly and a platform capable of relative movement, characterized in that: The printing assembly includes a first developing assembly and a second developing assembly; The first developing assembly comprises: A first developing medium rotates in a first fixed direction; a first developing engine for forming a first latent image on a developing surface of the first developing medium; a first material feeder, configured to provide printing material to the first latent image to form a first printing material layer; The second developing assembly includes: a second developing medium, rotating in a second fixed direction; a second developing engine for forming a second latent image on a developing surface of the second developing medium; a second material feeder, configured to provide printing material to the second latent image to form a second printing material layer; The first fixing direction is opposite to the second fixing direction; By adjusting the matching relationship between the first developer medium and the second developer medium, changing the number of times the first printing material layer is transferred from the first developer medium to the platform, and changing the number of times the second printing material layer is transferred from the second developer medium to the platform, the first printing material layer and the second printing material layer can be transferred to the platform during the first stroke and the second stroke of the lateral relative movement of the printing assembly and the platform, and the directions of the first stroke and the second stroke are opposite.

19. The three-dimensional printing device according to claim 18, characterized in that: Adjusting the matching relationship between the first developing medium and the second developing medium specifically includes adjusting the adsorption force of the first developing medium and the second developing medium on the first printing material layer and the second printing material layer respectively.

20. A three-dimensional printing method, using the three-dimensional printing device according to claim 18, characterized in that: During the printing process, when the printing assembly and the platform perform a first stroke of lateral relative movement, the first developer medium and the second developer medium are adjusted to cooperate so that the first printing material layer is transferred to the platform after N times, and the second printing material layer is transferred to the platform after N+1 times; when the printing assembly and the platform perform a second stroke of lateral relative movement, the first developer medium and the second developer medium are adjusted to cooperate so that the first printing material layer is transferred to the platform after N+1 times, and the second printing material layer is transferred to the platform after N times; wherein N is a natural number.

21. A three-dimensional printing method according to claim 20, characterized in that: The printing assembly and the platform perform a first stroke of lateral relative movement, adjusting the matching relationship between the first developer medium and the second developer medium so that the second printing material layer is transferred from the second developer medium to the first developer medium, and the first printing material layer and the second printing material layer form a composite printing material layer on the first developer medium, and the composite printing material layer is transferred from the first developer medium to the platform; The printing assembly and the platform move longitudinally relative to each other and move away from each other by a preset distance; The printing assembly and the platform perform a second stroke of lateral relative movement, adjusting the matching relationship between the first developer medium and the second developer medium so that the first printing material layer is transferred from the first developer medium to the second developer medium, the first printing material layer and the second printing material layer form a composite printing material layer on the second developer medium, and the composite printing material layer is transferred to the platform by the second developer medium; The printing assembly and the platform move longitudinally relative to each other and move away from each other by a preset distance; The above process is repeated, and the printing material layers transferred to the platform are solidified to achieve layer-to-layer bonding, and multiple layers of the printing material layers are stacked and bonded to form a final solidified model.

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