Polar line-of-sight projection light-curing printing apparatus and method

Abstract

The application discloses a polar coordinate line projection light curing printing device and method. The printing device comprises a printing shaft, a tank, a liquid changing device, a DLP light machine, a fine gap, a chuck, an extension rod and a theta axis stepping motor. The printing shaft extends into the tank containing resin. The liquid changing device can install different resins and resin cleaning liquid required for printing. The corresponding resin is input into the tank corresponding to the polar radius layer, and the resin cleaning liquid can be input into the tank before the resin is replaced for cleaning and extraction. The DLP light machine is used for displaying a linear pattern, which is irradiated on the printing shaft through the fine gap, so that the resin corresponding to the irradiated part of the printing shaft is cured. The theta axis stepping motor is used to drive the printing shaft to rotate. The application adopts the curing of resin on the printing shaft, realizes support-free printing, uses the fine gap to control the projection width, and further improves the printing precision. Based on the liquid changing device, the resin material is replaced at the specified polar radius layer in the printing process, and the nested composite material printing is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing, in particular to a polar coordinate line projection light-curing printing device and method. BACKGROUND

[0002] 3D printing technology is a rapid prototyping technology, which is based on a digital three-dimensional model file, uses photosensitive resin, molten plastic filament and other adhesive materials, and prints and bonds materials layer by layer to manufacture three-dimensional objects.

[0003] 3D printing technology is divided into Fused Deposition Modelling (FDM) and light-curing technology.

[0004] FDM technology uses molten plastic filament as material for three-dimensional printing. Its working principle is to melt the filament-shaped thermoplastic material through a nozzle, the nozzle bottom has a micro nozzle, under the control of a computer, the nozzle moves to the specified position according to the data of the three-dimensional model, and the liquid material in the molten state is sprayed out and finally solidified. The material is deposited on the solidified material of the previous layer after being sprayed, and the final product is formed by layer-by-layer accumulation of materials. FDM technology has the characteristics of high-temperature dissolution and re-solidification during printing, which can cause the mechanical properties of the printed product to deteriorate. In addition, the design requirements of the nozzle for this technology are high, and the printing precision is limited by the size of the nozzle. Reducing the nozzle aperture for printing precision can easily cause the extruded material to block at the nozzle port, causing the nozzle to fail to feed the material, affecting subsequent printing, and the process is complicated and the printing precision is difficult to control.

[0005] The basic principle of light-curing technology is: based on the three-dimensional model file of the product, the model is processed by slicing using software, and the contour pattern corresponding to the different levels of the model is obtained, which converts the three-dimensional object into a two-dimensional pattern. Then the photosensitive resin is introduced into the pool (the photosensitive resin in the pool will quickly solidify under light, thereby forming), the forming platform is placed in the pool, so that the forming end face of the platform is in contact with the photosensitive resin; then the data obtained by model slicing is introduced into the projection device to generate pattern light spots, and the resin exposed to light quickly solidifies; after the printing of this layer is completed, the forming platform is driven by the elevator to move upward by a small distance into the printing of the next layer, the light spots are replaced, and the printing of the next layer shape begins. In this way, the printing process is completed layer by layer, and the required 3D printed product is obtained.

[0006] The existing 3D printing technology is based on Cartesian coordinates with X, Y and Z three directions, which can take vertical or horizontal direction to print the printing structure, but the vertical printing will cause the printing time to increase with the growth of the printing structure, and no matter which direction, the existing 3D printing technology needs to design a support structure, which reduces the surface quality of the printed sample. At present, most of the light solidification 3D printing technologies on the market are up-drawing type printing, which is difficult to realize the printing of thin-walled printing objects (below 0.1 mm).

[0007] In addition, the existing light-cured printing nested composite material method is to print the inner layer material first, replace the printing resin after curing, then print the outer layer, and after completing the printing of the layer, the forming platform moves up and the same step is performed. Since the existing light-curing printing method is layer-by-layer printing, if nested composite materials are to be realized, the resin needs to be replaced in each layer of printing, and the efficiency of printing nested multi-material structures is very low, and the printing time increases with the increase of the layer height. Moreover, the existing light-curing printing method cannot realize the printing of different materials at different polar radii positions under polar coordinates. SUMMARY

[0008] In view of the above problems, the present application is proposed to provide a polar coordinate line projection light-curing printing device and method to overcome the above problems or at least partially solve the above problems.

[0009] The present application provides a polar coordinate line projection light-curing printing device, comprising:

[0010] a printing shaft, a tank, a liquid exchange device, a DLP light machine, a fine slot, a chuck, an extension rod and a theta axis stepping motor;

[0011] The tank is filled with resin, and the printing shaft extends into the tank filled with resin;

[0012] The liquid exchange device can install different resins and resin cleaning liquids required for printing, input corresponding resins to the tank corresponding to the polar radius layer, and can input resin cleaning liquid to the tank before replacing the resin for cleaning and extraction;

[0013] The DLP light machine is used to display a linear pattern, which is irradiated on the printing shaft through the fine slot, so that the resin corresponding to the irradiated part of the printing shaft is cured;

[0014] The chuck is fixed on the extension rod and connected to the theta axis stepping motor through the extension rod;

[0015] The chuck has different diameters, and the corresponding chuck is selected to clamp the printing shaft to keep the printing shaft in the vertical downward direction;

[0016] The printing shaft has different diameters and is clamped by the chuck.

[0017] The θ-axis stepping motor is used to drive the printing shaft to rotate.

[0018] Optionally, further comprising a horizontal sliding guide rail, a connecting plate and an R-axis stepping motor;

[0019] The θ-axis stepping motor is fixed on the horizontal sliding guide rail through the connecting plate.

[0020] The R-axis stepping motor is used to drive the horizontal sliding guide rail to move in the horizontal direction.

[0021] Optionally, further comprising a vertical sliding guide rail and a Z-axis stepping motor;

[0022] The Z-axis stepping motor is used to drive the vertical sliding guide rail to move in the vertical direction, so as to drive the printing shaft to extend into and move out of the material tank.

[0023] Optionally, further comprising a host computer, a motor driver, a liquid changing device controller and a DLP driver;

[0024] The host computer is used to control the θ-axis stepping motor, the R-axis stepping motor and the Z-axis stepping motor through the motor driver.

[0025] The host computer is used to realize the filling and cleaning of different resins in the material tank through the liquid changing device controller.

[0026] The host computer is used to control the DLP display pattern and light power through the DLP driver.

[0027] Optionally, the thin slit is made of a laser-processed metal sheet, and the minimum width is 0.01 mm; according to the required printing accuracy, a thin slit with a corresponding width is selected and installed on the material tank.

[0028] Optionally, the material tank has a socket for installing the thin slit, and the material tank also has a liquid outlet interface and a liquid inlet interface for connecting with the liquid changing device.

[0029] Optionally, the wavelength of the light output by the DLP light machine is 400-410 nm.

[0030] The application also provides a method for using the polar coordinate line projection light curing printing device, comprising:

[0031] Obtaining a polar coordinate slice of a three-dimensional model of a printing structure, and converting the polar coordinate slice into a plurality of projection patterns;

[0032] Displaying a target projection pattern through a DLP light machine;

[0033] The target projection pattern is irradiated on the printing shaft after passing through the slit, so that the resin corresponding to the irradiated part of the printing shaft is cured to complete the printing of the target projection pattern;

[0034] The printing shaft is rotated by a preset angle through the θ-axis stepping motor to complete the printing of other projection patterns of the current layer;

[0035] The printing shaft is horizontally moved by a preset distance to complete the printing of other layers.

[0036] Optionally, the polar coordinate slice of the three-dimensional model of the printing structure is obtained, and the polar coordinate slice is converted into a plurality of projection patterns, comprising:

[0037] A three-dimensional model of a printing structure is obtained and stored in a three-dimensional matrix;

[0038] According to the size of the printing structure voxel, a suitable width slit, a suitable thickness printing shaft and a suitable printing layer thickness are selected, the three-dimensional model of the printing structure is reconstructed to obtain a corresponding printing structure model;

[0039] The reconstructed printing structure model is layered in polar coordinates, the number of layers is determined according to the thickness of the printing structure and the set printing layer thickness, and each layer pattern is divided according to the selected slit width to obtain a slice pattern of the reconstructed printing model;

[0040] Each slice pattern of the reconstructed printing model is copied and combined into a projection pattern with an actual projection width greater than the slit width.

[0041] Optionally, it further comprises:

[0042] After the printing of the current layer is completed by using the first resin, the first resin is output by using the tank, and the cleaning liquid is input to clean and then output the cleaning liquid;

[0043] The second resin is input by using the tank to complete the printing of the next layer; and the process is repeated to complete the printing of all layers;

[0044] The printing structure with the shaft is taken out, and the surface residual resin of the printing structure is cleaned by using the cleaning liquid;

[0045] The printing structure is placed in hot water at a specified temperature for a preset time, and the printing structure is separated from the printing shaft by using the different thermal expansion coefficients of the printing shaft and the resin;

[0046] The printing structure is irradiated under the UV lamp to completely cure it.

[0047] The present application has the advantages that the present application uses a printing shaft, and by printing directly on the printing shaft, the need for designing supports in traditional area array printing can be avoided, and support-free printing is achieved, and the surface quality of the printed body is improved. The present application uses a fine slit to control the projection width, and the influence of the minimum pixel size of the projection device on the polar accuracy of printing is avoided, and the minimum fine slit width can reach 0.01 mm, and the printing accuracy is further improved. The present application can realize the printing of a multi-layer multi-material structure based on a liquid changing device, and by changing the resin material at a specified polar diameter layer during the printing process, nested composite material printing is achieved, and the problem that the prior art cannot realize the printing of a composite material structure using different materials at different polar coordinate diameter layers is overcome. Meanwhile, the present application separates the printing structure from the trough by rotating and rolling when the printing structure is completed once on the printing shaft, and in the prior art, the printing structure is directly pulled away from the release film, and compared with the prior art, the separation force between the printing body and the trough in the present application is smaller. The present application uses the gap between the printing shaft and the trough wall as the printing layer thickness, and can control the printing of a printing structure with a thinner wall thickness, and the thinnest wall thickness that can be achieved is 0.05 mm. The present application uses a replaceable printing shaft, and the printing shaft has different diameters, and the printing shaft with a suitable diameter can be selected according to the size of the printing structure.

[0048] After the printing is completed, the printing structure is separated from the printing shaft by using the difference in the thermal expansion coefficient between the resin and the printing shaft material, and the shaft printing structure is placed in hot water at a specified temperature for a preset time, so that the printing structure is easily separated from the printing shaft. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 A structure schematic diagram of a polar coordinate line projection light curing printing device of an embodiment of the present application;

[0050] Figure 2 A control principle diagram of a polar coordinate line projection light curing printing device of an embodiment of the present application;

[0051] Figure 3 A flowchart schematic diagram of a polar coordinate line projection light curing printing method of an embodiment of the present application;

[0052] Figure 4 A principle diagram of a polar coordinate line projection light curing printing method of an embodiment of the present application;

[0053] Figure 5 A schematic diagram of converting a slice pattern into a projection pattern of an embodiment of the present application, and the actual projection width of the generated projection pattern is much larger than the fine slit width;

[0054] Figure 6 A polar coordinate slice generation schematic diagram of an embodiment of the present application;

[0055] Figure 7The width of the maximum and minimum fine slit and the printing precision measurement value used for printing of an embodiment of the present application;

[0056] Figure 8 A schematic diagram of a 3-layer model printing result printed by an embodiment of the present application at a 100-micron fine slit and a 3-mm diameter printing shaft;

[0057] Figure 9 A multi-layer screwdriver model printed by an embodiment of the present application at a 100-micron fine slit, a 2-mm diameter printing shaft, and a schematic diagram of a printing result;

[0058] Figure 10 A schematic diagram of a 50-micron layer-thick blood vessel stent model printing result printed by an embodiment of the present application at a 100-micron fine slit, a 6-mm diameter printing shaft;

[0059] Figure 11 A schematic diagram of a 50-micron layer-thick tubular model printing result printed by an embodiment of the present application at a 100-micron fine slit, a 6-mm diameter printing shaft. DETAILED DESCRIPTION

[0060] The basic principle of the present application is to replace the forming platform in the light-curing printing of the prior art with a printing shaft, obtain slice data of a three-dimensional model of a printing structure and convert the slice data into a projection pattern, and use a DLP light machine to perform projection. After the projection passes through a fine slit, the resin of the corresponding width pattern on the printing shaft is cured, the printing shaft is rotated by an angle under the driving of a θ-axis stepping motor after the current projection pattern is completely cured, printing of the next projection pattern is performed, and the process is repeated until the printing of the layer is completed. Subsequently, the printing shaft is horizontally moved by a preset distance to complete the printing of other layers, and the printing of the next layer is started. During the printing process, the resin with corresponding characteristics can be replaced at different polar radii layers according to the requirements of the printing structure, and finally the printing is completed.

[0061] To make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings. Figure 1 A schematic diagram of the structure of a polar coordinate line projection light-curing printing device according to an embodiment of the present application is shown in FIG. 1. As shown in the figure, the printing device comprises: Figure 1

[0062] a printing shaft 1, a tank 3, a liquid changing device 16, a DLP light machine 5, a fine slit 4, a chuck 14, an extension rod 13 and a θ-axis stepping motor 9;

[0063] The tank 3 is filled with resin 2, and the printing shaft 1 extends into the tank 3 filled with the resin 2;

[0064] ​The liquid changing device 16 can install different resins and resin cleaning liquid required for printing, input corresponding resin to the tank 3 corresponding to the polar radius layer, and can input resin cleaning liquid to the tank 3 before changing the resin to clean and extract;

[0065] The DLP light machine 5 is used to display a linear pattern, and is irradiated on the printing shaft 1 through the slit 4, so that the resin corresponding to the light irradiation part on the printing shaft 1 is solidified;

[0066] The chuck 14 is fixed on the extension rod 13 and connected with the theta axis stepping motor 9 through the extension rod 13;

[0067] The chuck 14 has different diameters, and the corresponding chuck is selected to clamp the printing shaft 1, so that the printing shaft 1 is kept in the vertical downward direction;

[0068] The printing shaft 1 has different diameters and is clamped by the chuck 14;

[0069] The theta axis stepping motor 9 is used to drive the printing shaft 1 to rotate.

[0070] In actual application, the printing shaft 1 is close to the direction of the slit 4, and is spaced from the wall of the tank 3 by a distance of the printing thickness of each layer, the side close to the printing shaft 1 in the tank 3 is pasted with a Teflon tape, which is used for printing shaft to be separated from the wall. The resin can be a photosensitive rigid resin or a water washing resin with a wavelength of 405 nanometers.

[0071] It can be understood that the FDM technology has the characteristics of high temperature dissolution and re-solidification in the printing process, which can cause the mechanical properties of the printed product to be poor, the mechanical properties of the printed body are difficult to control, and the design requirements of the nozzle are high. The printing precision is limited by the size of the nozzle. While improving the printing precision, due to the reduction of the nozzle aperture, the extruded material is easy to block at the nozzle port, which causes the nozzle to be unable to send the wire, affects the subsequent printing, the process is complicated, and the printing precision is difficult to control. The embodiment of the present application is based on the principle of light curing, which can provide higher printing precision, and different width slits can be replaced according to different printing requirements to realize printing with a resolution less than DLP projection.

[0072] The polar coordinate line projection light curing printing device of the embodiment of the present application utilizes a printing shaft, and can avoid the shortcoming of needing to design support in traditional surface array printing, realizes support-free printing, and improves the surface quality of the printed body. The present application uses a fine gap to control the projection width, avoids the influence of the minimum pixel size of the projection device on the printing polar precision, and the minimum fine gap width can reach 0.01 mm, further improving the printing precision. The present application can realize the printing of multi-layer and multi-material structures based on the liquid changing device, and realizes nested composite material printing by changing the resin material at a specified polar radius layer during the printing process, overcoming the problem that the prior art cannot realize the printing of composite material structures using different materials at different polar coordinate diameter layers. Meanwhile, the present application separates the printing structure from the trough by rotating and rolling when the printing structure is cured on the printing shaft once, while in the prior art, the printing structure is directly pulled away from the release film, and compared with the prior art, the separation force between the printing body and the trough of the present application is smaller. The present application uses the gap between the printing shaft and the trough wall as the printing layer thickness, can control the printing structure with a thinner printing wall thickness, and the thinnest wall thickness printing can realize 0.05 mm.

[0073] In an optional embodiment of the present application, the printing device further comprises a horizontal sliding guide rail 15, a connecting plate 12 and an R-axis stepping motor 8;

[0074] The θ-axis stepping motor 9 is fixed on the horizontal sliding guide rail 15 through the connecting plate 12;

[0075] The R-axis stepping motor 8 is used to drive the horizontal sliding guide rail 15 to move in the horizontal direction.

[0076] Further, the device further comprises a vertical sliding guide rail 11 and a Z-axis stepping motor 10;

[0077] The Z-axis stepping motor 10 is used to drive the vertical sliding guide rail 11 to move in the vertical direction, and drive the printing shaft 1 to extend into and move out of the trough 3.

[0078] Further, with reference to Figure 2 , further comprising an upper computer 6, a motor driver 7, a liquid changing device controller 17 and a DLP driver;

[0079] The upper computer 6 is used to control the θ-axis stepping motor 9, the R-axis stepping motor 8 and the Z-axis stepping motor 10 through the motor driver 7;

[0080] The upper computer 6 is used to realize the loading and cleaning of different resins of the trough 3 through the liquid changing device controller 17;

[0081] The upper computer 6 is used to control the DLP display pattern and light power through the DLP driver.

[0082] Further, the theta-axis stepper motor 9, the R-axis stepper motor 8 and the Z-axis stepper motor 10 are connected to the motor driver 7 respectively. The motor driver 7 can set the step angle of the motor per rotation, and through writing control code in the host computer 6, the rotation angle and time of the motor can be controlled, so as to realize the movement of the printing shaft 1 in the printing process.

[0083] It can be understood that after the DLP outputs the projection pattern, the pattern light can be formed by the fine slit irradiating on the printing shaft 1, and the pattern light formed is the pattern light limited to the width of the fine slit. The pattern light irradiates on the printing shaft 1, and after a period of time, the resin corresponding to the light irradiation part on the printing shaft 1 is cured. The theta-axis stepper motor 12 drives the printing shaft to rotate by an angle, and at the same time, the DLP projects the next projection pattern to start the next printing. Each time the printing and curing area is a line, and until the printing shaft rotates a circle, the printing of the first layer is completed. Then the R-axis stepper motor 8 drives the printing shaft 1 to move a distance, and the printing of the next layer starts.

[0084] Further, the fine slit 4 is made of laser processing cutting metal sheet, and the minimum width is 0.01 millimeter. According to the required printing accuracy, the fine slit 4 with corresponding width is selected and installed on the trough 3.

[0085] The trough 3 has a socket for installing the fine slit 4, and the trough 4 also has a liquid outlet interface and a liquid inlet interface for docking with the liquid changing device 16.

[0086] In actual application, the wavelength of the light output by the DLP light machine is 400-410 nanometers. Preferably, in order to improve the resin curing effect, the wavelength of the light output by the DLP light machine is 405 nanometers.

[0087] Figure 3 The flowchart of the polar coordinate line projection light curing printing method of an embodiment of the present application is shown. The method uses the light curing printing device as described above to print. As shown in the figure, the method comprises the following steps. Figure 3

[0088] S31: obtaining the polar coordinate slice of the three-dimensional model of the printing structure, and converting the polar coordinate slice into a plurality of projection patterns;

[0089] S32: displaying the target projection pattern by the DLP light machine;

[0090] S33: after the target projection pattern passes through the fine slit and irradiates on the printing shaft, the resin corresponding to the light irradiation part on the printing shaft is cured, so as to complete the printing of the target projection pattern;

[0091] S34: rotating the printing shaft by a preset angle by the theta-axis stepper motor, and completing the printing of other projection patterns of the current layer; ​

[0092] S35: horizontally moving the printing shaft by a preset distance to complete printing of other layers.

[0093] The polar coordinate line projection light curing printing method of the embodiment of the present application uses a printing shaft to directly print on the printing shaft, which can avoid the shortcoming of designing supports in traditional face array printing, realizes support-free printing, and improves the surface quality of the printed body. The present application uses a fine gap to control the projection width, which avoids the influence of the minimum pixel size of the projection device on the printing polar precision, and the minimum fine gap width can reach 0.01 mm, further improving the printing precision. The present application can realize the printing of multi-layer and multi-material structures based on the liquid exchange device, which realizes the printing of nested composite materials by replacing the resin material at a specified polar radius layer during the printing process, and overcomes the problem that the prior art cannot realize the printing of composite material structures using different materials at different polar coordinate diameter layers. At the same time, the printing structure is separated from the trough by rotating and rolling when the printing structure is cured on the printing shaft each time, while in the prior art, the printing structure is directly pulled away from the release film. Compared with the prior art, the separation force between the printed body and the trough in the present application is smaller. The present application uses the gap between the printing shaft and the trough wall as the printing layer thickness, which can control the printing of thinner printing structures, and the thinnest wall thickness that can be achieved is 0.05 mm. The present application uses a replaceable printing shaft, and the printing shaft has different diameters, which can select a printing shaft with a suitable diameter according to the size of the printing structure.

[0094] Figure 4 The principle diagram of the polar coordinate line projection light curing printing method of an embodiment of the present application is shown in FIG. 1. Figure 4 As shown in FIG. 1, the printing method of the embodiment of the present application includes:

[0095] ① The motor controls the printing shaft to extend into the trough;

[0096] ② The liquid exchange device inputs the first resin into the trough;

[0097] ③ The DLP light machine projects the projection pattern of the first resin, and the motor controls the printing shaft to rotate and translate to complete the corresponding layer of the first resin;

[0098] ④ The liquid exchange device outputs the first resin, and the motor controls the printing shaft to translate by a layer distance;

[0099] ⑤ The liquid exchange device uses a resin cleaning liquid to complete the flushing of the trough and the printed body;

[0100] ⑥ After completing the printing, the motor controls the printing shaft to leave the trough.

[0101] In an optional embodiment of the present application, the polar coordinate slice of the three-dimensional model of the printing structure is obtained, and the polar coordinate slice is converted into a plurality of projection patterns, which includes:

[0102] Acquire the three-dimensional model of the printing structure and store it in a three-dimensional matrix;

[0103] According to the voxel size of the printing structure, select a suitable width of the fine slit, a suitable thickness of the printing shaft, and a suitable thickness of the printing layer, reconstruct the three-dimensional model of the printing structure to obtain a corresponding printing structure model;

[0104] Layer the reconstructed printing structure model in polar coordinates, the number of layers is determined according to the thickness of the printing structure and the set printing layer thickness, and then separate each layer pattern according to the selected slit width to obtain the slice pattern of the reconstructed printing model;

[0105] Copy and merge each slice pattern of the reconstructed printing model into a projection pattern with an actual projection width greater than the slit width.

[0106] As shown in Figure 5 Each line slice pattern of the reconstructed printing model is copied and merged into a projection pattern with an actual projection width W greater than the slit width w. In each layer picture, it is divided into black and white regions, where the white region corresponds to the model, representing light, and the black region has no model, representing no light.

[0107] Further, it also includes:

[0108] After using the first resin to complete the printing of the current layer, the first resin is output by the tank, and the cleaning liquid is input to clean and then output the cleaning liquid;

[0109] The second resin is input by the tank to complete the printing of the next layer; in this way, all layers are printed;

[0110] Take out the printing structure with the shaft, and clean the surface of the printing structure with the cleaning liquid;

[0111] Put the printing structure into hot water at a specified temperature for a preset time, and use the different thermal expansion coefficients of the printing shaft and the resin to make the printing structure and the printing shaft separate;

[0112] Irradiate the printing structure under the UV lamp to make it completely cured.

[0113] In practical application, the shaft printing structure is immersed in 80 degrees Celsius hot water for 3 to 5 minutes, so that the printing structure is easily separated from the printing shaft.

[0114] It can be understood that, after the printing is completed, the printing structure is separated from the printing shaft by using the different thermal expansion coefficients of the resin and the printing shaft material, putting the shaft printing structure into hot water at a specified temperature for a preset time, so that the printing structure is easily separated from the printing shaft.

[0115] The printing principle and printing result of the embodiment of the present application are described below. Figures 6-11 ​

[0116] Figure 6 Schematic diagram of polar coordinate slice for one embodiment of the present application. (a) is the process of generating polar coordinate slice; (b) is a schematic diagram of the printing process of a tubular model of three kinds of materials in a vat, O is the center of the rotation axis, θ j is the polar angle corresponding to the width of each projection during printing; (c) is an enlarged view of the inner part of (b), E is the printing layer thickness, w is the width of the thin slit, e i is the layer thickness of the corresponding kind of material, γ is the layer thickness of each layer during printing; (d) is a top view of (b), the coordinate axis is the corresponding polar coordinate polar radius R axis, Φ is the radius of the corresponding printing axis, θ1 and θ N are the polar angle sizes required for the first layer and the Nth layer to print a projection during printing, respectively, which are determined by the thin slit width w and the polar radius of the printing position; (e) is the slice diagram of each layer after polar coordinate slicing of the model (b), a total of 6 layers, l1, l2 and l3 represent the slice number of the printing layer of the three kinds of materials, respectively.

[0117] Figure 7 The maximum and minimum widths of the thin slit used for printing and the printing precision measurement value for one embodiment of the present application. (a) is the minimum thin slit used in the present application, with a width of 10 microns; (b) is the result of printing a thin strip-shaped object using a 10-micron thin slit in the present application, from left to right, the actual widths of 5, 4, 3, 2, and 1 projections are printed; (c) is the 100-micron thin slit used in the present application; (d) is the result of printing a strip-shaped object using a 100-micron thin slit in the present application, from left to right, the actual widths of 5, 4, 3, 2, and 1 projections are printed.

[0118] Figure 8 Schematic diagram of the printing result of a 3-layer model printed using a 100-micron thin slit and a 3-millimeter diameter printing axis for one embodiment of the present application. The second layer is yellow resin, and the first and third layers are white resin, with a scale of 3 millimeters. (a), (b), and (c) are the printed bodies after the first, second, and third layers are printed, respectively; (d) is a three-dimensional model of the printed body; (e), (f), and (g) are the line slice patterns of each layer of the model (d).

[0119] Figure 9 Schematic diagram of a multi-layer screwdriver model and the printing result printed using a 100-micron thin slit and a 2-millimeter diameter printing axis for one embodiment of the present application. Figure 9 The scale is 2 millimeters. (a) is a three-dimensional model of a screwdriver; (b) is the printing result of the screwdriver.

[0120] Figure 10Figure 1 shows a schematic diagram of a printing result of a 50-micron-thick vascular stent model printed by an embodiment of the present application on a 100-micron-thin slit, 6-mm-diameter printing shaft. Figure 10 Figure 1 shows a schematic diagram of a printing result of a 50-micron-thick vascular stent model printed by an embodiment of the present application on a 100-micron-thin slit, 6-mm-diameter printing shaft.

[0121] Figure 11 Figure 2 shows a schematic diagram of a printing result of a 50-micron-thick tubular model printed by an embodiment of the present application on a 100-micron-thin slit, 6-mm-diameter printing shaft.

[0122] In summary, the present application uses a printing shaft to print directly on the printing shaft, which avoids the need to design supports in traditional area array printing, and achieves support-free printing and improves the surface quality of the printed body. The present application uses a thin slit to control the projection width, which avoids the influence of the minimum pixel size of the projection device on the printing polar accuracy, and the minimum slit width can reach 0.01 mm, further improving the printing accuracy. The present application can realize the printing of multi-layer and multi-material structures based on a liquid exchange device, which replaces the resin material at a specified polar radius layer during printing, realizes nested composite material printing, and overcomes the problem that the prior art cannot realize the printing of composite material structures using different materials at different polar diameters. At the same time, the present application separates the printed structure from the trough by rotating and rolling when the printing structure is completed on the printing shaft, while in the prior art, the printed structure is directly pulled away from the release film. Compared with the prior art, the separation force between the printed body and the trough in the present application is smaller. The present application uses the gap between the printing shaft and the trough wall as the printing layer thickness, which can control the printing of thinner printed structures, and the thinnest wall thickness that can be achieved is 0.05 mm. The present application uses a replaceable printing shaft, and the printing shaft has different diameters, which can be selected according to the size of the printed structure.

[0123] After printing is completed, the present application separates the printed structure from the printing shaft by using the difference in the thermal expansion coefficient between the resin and the printing shaft material, placing the shaft-printed structure in hot water at a specified temperature for a predetermined time, and making the printed structure easy to separate from the printing shaft.

[0124] In the description provided herein, a large number of specific details are described. However, it can be understood that embodiments of the present application can be practiced without these specific details. In some examples, well-known methods, structures and techniques are not shown in detail in order not to obscure the understanding of the present description.

[0125] Similarly, it is to be understood that the embodiments of the present application can be alternately grouped together in a single embodiment, figure, or description of embodiments thereof for the purpose of brevity and understanding in the interest of conciseness and didacticism. However, this approach to disclosure should not be interpreted as reflecting an intention that the claimed application requires more features than are explicitly recited in each claim. Rather, inventive aspects are defined solely in the claims below, as reflected in the claims section below. Thus, the claims following, specifically the claims section, are hereby expressly incorporated into this detailed description of embodiments of the present application, and they are made part of the specification to the same extent as if each were individually duly incorporated by reference.

[0126] Those skilled in the art will appreciate that the modules in the apparatus of the embodiments can be adapted and placed in one or more apparatuses other than the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and further can be split into more sub-modules or sub-units or sub-components. Any combination of all the features disclosed in the specification (including the accompanying claims, abstract and drawings), and any method or of the apparatuses so disclosed, can be made unless the contrary is explicitly stated in the specification (including the accompanying claims, abstract and drawings), or otherwise readily apparent from the context using no more than a modest degree of ingenuity. Unless specifically stated otherwise, each feature disclosed in the specification (including the accompanying claims, abstract and drawings), and / or the steps of any method or of the apparatuses so disclosed, can be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

[0127] Furthermore, those skilled in the art will recognize that references in the specification to "one embodiment", "an embodiment", "an example embodiment", etc., mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, appearances of the phrases "in one embodiment" or "an embodiment" are not necessarily referring to the same embodiment.

[0128] Embodiments of the various components of the application can be implemented in hardware, or as software modules running in one or more processors, or in combinations thereof. Skilled persons will appreciate that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components in an apparatus according to embodiments of the application. The application can also be implemented as a program (for example, a computer program and a computer program product) for performing part or all of the methods described herein on an apparatus or device. Such program(s) can be stored on a computer readable medium which can be any medium, tangible or intangible, in which data can be stored and which can be accessed by a computer. Such a medium might take the form of a data storage unit, a computer hard drive, a solid state drive, a RAM, a ROM, a flash drive, a portable memory stick, a database, a cloud-based storage unit, or any other suitable medium. Such a medium might further take the form of a data signal, a data stream, a data bit, a data baseband signal, a data carrier wave, a data modulated wave, or any other suitable medium. Such a medium can be downloaded into the memory of a computer or device from an internet website, a cloud storage unit, or any other suitable source.

[0129] The above description is only a specific implementation of the present application. Based on the above teaching, those skilled in the art can make other improvements or modifications on the basis of the above embodiments. Those skilled in the art should understand that the above specific description is only for better explaining the purpose of the present application, and the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A polar coordinate line projection light-curing printing device, characterized in that: It comprises: a printing shaft, a tank, a liquid changing device, a DLP light machine, a slit, a chuck, an extension rod and a θ-axis stepping motor; The tank is filled with resin, and the printing shaft extends into the tank filled with resin. The liquid changing device can install different resins and resin cleaning liquids required for printing, input corresponding resins into the tank according to the polar coordinate layer, and input resin cleaning liquids into the tank before changing resins for cleaning and extraction. The DLP light machine is used to display a linear pattern, which is irradiated on the printing shaft through the slit, so that the resin corresponding to the light irradiation part of the printing shaft is solidified. The chuck is fixed on the extension rod and connected to the θ-axis stepping motor through the extension rod. The chuck has different diameters, and the corresponding chuck is selected to clamp the printing shaft to keep the printing shaft in a vertical downward direction. The printing shaft has different diameters and is clamped by the chuck. The θ-axis stepping motor is used to drive the printing shaft to rotate.

2. The apparatus of claim 1, wherein, It also includes a horizontal sliding guide, a connecting plate and an R-axis stepping motor. The θ-axis stepping motor is fixed on the horizontal sliding guide through the connecting plate. The R-axis stepping motor is used to drive the horizontal sliding guide to move in the horizontal direction.

3. The apparatus of claim 1, wherein, It also includes: a vertical sliding guide and a Z-axis stepping motor; The Z-axis stepping motor is used to drive the vertical sliding guide to move in the vertical direction, and the printing shaft extends into and moves out of the tank.

4. The apparatus of claim 1, wherein, It also includes: a host computer, a motor driver, a liquid changing device controller and a DLP driver; The host computer is used to control the θ-axis stepping motor, R-axis stepping motor and Z-axis stepping motor through the motor driver; The host computer is used to realize the filling and cleaning of different resins in the tank through the liquid changing device controller; The host computer is used to control the DLP display pattern and light power through the DLP driver.

5. The apparatus of claim 1, wherein, The slit is made of laser processing and cutting metal sheet, with a minimum width of 0.01 mm. According to the required printing accuracy, the slit with corresponding width is installed on the tank.

6. The apparatus of claim 1, wherein, The tank has a socket for installing the slit, and also has a liquid outlet interface and a liquid inlet interface for connecting with the liquid changing device.

7. The apparatus of claim 1, wherein, The wavelength of the light output by the DLP light machine is 400-410 nm.

8. A polar line-of-sight projection light-curing printing method using the apparatus of any one of claims 1-7, characterized by, It comprises: obtaining polar coordinate slices of a three-dimensional model of a printing structure, and converting the polar coordinate slices into a plurality of projection patterns; displaying a target projection pattern through a DLP light machine; The target projection pattern is irradiated on the printing shaft after passing through the slit, so that the resin corresponding to the light irradiation part of the printing shaft is solidified to complete the printing of the target projection pattern; The printing shaft is rotated by a θ-axis stepping motor by a preset angle to complete the printing of other projection patterns of the current layer; The printing shaft is moved horizontally by a preset distance to complete the printing of other layers.

9. The method of claim 8, wherein, The method for obtaining polar coordinate slices of a three-dimensional model of a printing structure and converting the polar coordinate slices into a plurality of projection patterns comprises: obtaining a three-dimensional model of a printing structure and storing it in a three-dimensional matrix; According to the selection of the appropriate width of the fine slit, the appropriate thickness of the printing axis and the appropriate printing layer thickness according to the voxel size of the printing structure, the three-dimensional model of the printing structure is reconstructed to obtain the corresponding printing structure model; The reconstructed printing structure model is layered in polar coordinates, the number of layers is determined according to the thickness of the printing structure and the set printing layer thickness, and each layer pattern is separated according to the selected slit width to obtain the slice pattern of the reconstructed printing model; Each slice pattern of the reconstructed printing model is copied and combined into a projection pattern with a projection width greater than the slit width.

10. The method of claim 8, wherein, Also includes: After using the first resin to complete the printing of the current layer, the first resin is output by the tank, and the cleaning liquid is input and output after cleaning; The second resin is input by the tank to complete the printing of the next layer; In this way, all layers are printed; The printing structure with the shaft is taken out, and the surface of the printing structure is cleaned with the cleaning liquid; The printing structure is placed in hot water at a specified temperature for a preset time, and the different thermal expansion coefficients of the printing shaft and the resin make the printing structure and the printing shaft separate; The printing structure is irradiated under the UV lamp to completely solidify.

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