Powder adhesive jet printing equipment and printing method

Abstract

The invention provides powder adhesive jet printing equipment and a printing method.The powder adhesive jet printing equipment comprises a powder laying system, a heating system, a negative pressure ink supply printing system, a powder layer compacting system, a forming cylinder system and a material cylinder system, the powder layer compacting system is arranged between the powder laying system and the negative pressure ink supply printing system, and the forming cylinder system is arranged between the powder laying system and the negative pressure ink supply printing system; the powder layer compacting system comprises a pressing plate, the pressing plate can move in the vertical direction and can also move in the horizontal direction, the vertical direction and the horizontal direction can be simultaneously and respectively achieved in the powder layer compacting process so that the powder layer can be compacted, and each printing layer can be compacted in the printing process. According to the device, each printing layer can be compacted in the part printing process, so that the density of the printed part biscuit is greatly improved, the printed part biscuit is easier to form, the strength is improved, and the high-strength part biscuit is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of powder materials and 3D printing, and in particular to a powder adhesive jet printing device and a printing method. Background Art

[0002] Additive Manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention and favor in industrial production because it can produce personalized products of various shapes compared to traditional processes. Binder Jetting (BJ) is an important AM process. This method selectively deposits the material in the powder layer by spraying a liquid binder, and heats and solidifies it to form a rough part with a certain strength. Finally, it is further densified by degreasing and sintering to obtain the final part with the required density and mechanical properties. BJ technology has the advantages of low cost, fast printing speed, high resolution and no need for support structures to achieve complex geometric shapes. These advantages have great potential for mass industrial production. BJ technology can use almost any kind of granular material and various particle sizes. In industrial production applications, it can be widely used in many fields such as automobiles, machinery, medical care, electronics, aerospace, etc., covering all aspects of people's food, clothing, housing and transportation.

[0003] Binder jetting technology is a 3D printing method based on droplet jetting and powder bonding of powder raw materials. Its core mechanism is the interaction between liquid binder and powder and their bonding force. This process determines the mechanical strength, geometric accuracy and powder removal ability of the blank. The printing process of this technology is that the powder spreading device of the equipment first spreads the powder into a flat layer, and then the print head carrying the liquid binder selectively sprays the liquid binder at the position of the desired shape, and then the powder bed drops to a layer thickness, and the "powder spreading-binder spraying" operation is repeated until the part is printed.

[0004] During the printing and powder spreading process, the newly applied powder layer and the bonded powder layer underneath are loosely superimposed on each other, which makes the final part blank have a lower density and a lower volume solid content. The part will have a higher volume shrinkage rate in the subsequent sintering process and it will be difficult to sinter densely.

[0005] Since the powder binder jet printing device in the prior art has technical problems such as low density of the blank parts printed, resulting in low formability and strength, the present invention studies and designs a powder binder jet printing device and a printing method. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of low density of the part blanks printed by the powder adhesive jet printing equipment in the prior art, resulting in low formability and strength, thereby providing a powder adhesive jet printing equipment and printing method.

[0007] In order to solve the above problems, the present invention provides a powder adhesive jet printing device, which includes:

[0008] A powder spreading system, a heating system, a negative pressure ink supply printing system, a powder layer compacting system, a forming cylinder system and a material cylinder system. The powder layer compacting system is arranged between the powder spreading system and the negative pressure ink supply printing system. The powder layer compacting system includes a pressing plate. The pressing plate can move in both vertical and horizontal directions. During the process of compacting the powder layer, it can simultaneously and separately realize vertical and horizontal movements to compact the powder layer, and each printing layer can be compacted during the printing process.

[0009] In some embodiments,

[0010] The powder layer compaction system also includes a hydraulic device, a pressure sensor, an electric lifting mechanism and a motor. The pressure sensor is arranged on the pressing plate to detect the pressure applied by the pressing plate on the powder layer. The motor is connected to the hydraulic device to drive the hydraulic device to operate. The hydraulic device is connected to the pressing plate through the electric lifting mechanism to drive the pressing plate to move in vertical and horizontal directions.

[0011] In some embodiments,

[0012] The molding cylinder system includes a molding cylinder, the shape of the pressing plate is consistent with the shape of the molding cylinder, the length dimension of the pressing plate is M, the unit is mm, the length dimension of the molding cylinder corresponding to the pressing plate is N, the unit is mm, and the following relationship exists: -3≤MN≤5.

[0013] In some embodiments,

[0014] The lower surface of the pressing plate is a finely polished plane, and its surface roughness value Ra is less than 1 μm.

[0015] In some embodiments,

[0016] The lower surface of the pressing plate is parallel to the upper surface of the forming cylinder, and the angle between the two planes is less than 0.5°.

[0017] In some embodiments,

[0018] The pressure generated by the hydraulic device can be adjusted within the range of 0-20 MPa.

[0019] In some embodiments,

[0020] It also includes a horizontal guide rail, the powder spreading system includes a powder spreading roller, the negative pressure ink supply printing system includes a negative pressure ink supply circulation system and a print nozzle, the negative pressure ink supply circulation system can spray adhesive to the powder layer on the printing area through the print nozzle, the heating system includes a heating lamp, and the heating lamp, the powder spreading roller, the pressure plate and the print nozzle are arranged in sequence in the moving direction along the horizontal guide rail.

[0021] The present invention also provides a printing method of the aforementioned powder adhesive jet printing device, which includes: feeding and powder spreading operations: lowering the height of the material cylinder from the highest limit to a preset height according to the height of the printed part, pouring the raw material powder into the material cylinder, setting the powder spreading parameters and starting the powder spreading operation until the powder spreading operation is completed after the surface of the forming cylinder is flattened;

[0022] Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part;

[0023] The starting printing operation includes:

[0024] (1) The powder roller spreads a layer of powder on the forming cylinder;

[0025] (2) The pressing plate compacts the powder at a set pressure value, and the holding time can be set between 1s and 15s;

[0026] (3) The print head sprays the binder in the set selected area, and the spraying amount and the number of spraying scans can be adjusted according to the actual situation;

[0027] (4) The heating lamp sweeps across the molding cylinder area to accelerate the curing of the area where the adhesive has just been sprayed.

[0028] (5) The above components then return to the coordinate zero point along with the guide rail, and then continue to repeat the above steps (1)-(4) until the printing program is completed.

[0029] In some embodiments,

[0030] Before the material loading and powder spreading operations, there are steps of printing the model and powering on; between the material loading and powder spreading operations and the start of the printing operation, there is a step of setting parameters; after the start of the printing operation, there is a curing step, which forms the following steps in total:

[0031] 1) Design the 3D model of the part to be printed according to actual needs, select the printing material, set the layer thickness, and slice to generate a .cli file;

[0032] 2) Power on the printing device, run the negative pressure inkjet system, and then return all axes of the device to zero;

[0033] 3) Loading and powder spreading operation: lower the height of the material cylinder from the highest limit to the preset height according to the height of the printed parts, pour the raw material powder into the material cylinder, set the powder spreading parameters and start the powder spreading action until the surface of the forming cylinder is flattened;

[0034] 4) Import the processing file, i.e. .cli slice file, into the device computer and set the appropriate printing parameters and the powder pressing pressure value of the pressing plate;

[0035] 5) Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part;

[0036] 6) Take out the blank part and transfer it into an oven for curing at a certain temperature and insulation time to finally obtain a high-strength blank part.

[0037] In some embodiments,

[0038] The raw material powder is at least one of metal powder, ceramic powder and alloy powder; when the pressing plate is compacting the powder, the center point of the pressing plate and the center point of the forming cylinder are aligned, and the position deviation is less than ±0.3mm;

[0039] The pressure value of the pressing plate on the powder layer is selected and determined according to the substance, particle size and thickness of the powder material selected.

[0040] The thickness of a single powder layer is in the range of 0.08mm-0.4mm.

[0041] The powder adhesive jet printing device and printing method provided by the present invention have the following beneficial effects:

[0042] 1. The present invention provides a powder layer compacting system between the powder spreading system and the negative pressure supply printing system. The powder layer compacting system includes a pressing plate. The pressing plate can compact the powder layer, especially each printing layer. The pressing plate can move in both the vertical and horizontal directions. In the process of compacting the powder layer, the pressing plate can simultaneously and separately realize vertical and horizontal movements to compact the powder layer. In the process of printing parts, each printing layer can be compacted, so that the density of the printed part blank is greatly improved, and it is easier to form, improve the strength, and obtain a high-strength part blank. This effectively solves the problem that in the prior art of preparing part blanks with BJ equipment, the powder of each printing layer is relatively loosely accumulated, resulting in a low density of the final printed part blank and difficulty in forming, which is also not conducive to the subsequent block densification sintering.

[0043] 2. The present invention further adjusts and optimizes the relationship between the layer thickness and the applied pressure, especially by satisfying -3≤MN≤5 between the length dimension M of the pressing plate and the corresponding length dimension N of the forming cylinder, and the pressure generated by the hydraulic device is within the range of 0-20MPa, and the thickness of the single powder layer of the powder is set at 0.08mm-0.4mm, which can further improve the density of the printed part blank, further improve the strength of the product, and make it easier to form. The powder adhesive jet printing equipment of the present invention and the process method for printing the part blank, the gain effect in the aspects of formability and blank density are universal and universal for various printing materials, printing shapes, printing parameters and subsequent curing and sintering processes, the equipment modification cost is low, the research and development efficiency is greatly improved, and the production cost is reduced. The present invention further sets the thickness of the single powder layer of the powder at 0.08mm-0.4mm, and further preferably 0.15-0.3mm, which can improve the production cycle of part printing, reduce the amount of binder used, and thus reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a top view of the binder jetting-3D printing apparatus of the present invention;

[0045] Figure 2 is a front view of the binder jetting-3D printing device of the present invention.

[0046] The reference numerals are as follows:

[0047] 1. Powder spreading system; 11. Powder spreading roller; 2. Heating system; 21. Heating lamp; 3. Negative pressure ink supply printing system; 31. Negative pressure ink supply circulation system; 32. Print nozzle; 4. Powder layer compaction system; 41. Pressing plate; 42. Hydraulic device; 43. Pressure sensor; 44. Electric lifting mechanism; 45. Motor; 5. Forming cylinder system; 51. Forming cylinder; 6. Material cylinder system; 61. Material cylinder; 7. Horizontal guide rail; 8. Raw material powder; 9. Adhesive injection printing area; 10. The sinking part of the part; 12. Motor control and belt transmission structure; 13. Moving parts; 14. Equipment table; 15. Powder bed. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0050] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0051] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0052] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0053] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0054] like Figure 1-2 As shown, the present invention provides a powder adhesive jet printing device, which includes:

[0055] A frame, a powder spreading system 1, a heating system 2, a negative pressure ink supply printing system 3, a powder layer compacting system 4, a control system, a forming cylinder system 5 and a material cylinder system 6. The powder layer compacting system 4 is arranged between the powder spreading system 1 and the negative pressure ink supply printing system 3. The powder layer compacting system 4 includes a pressing plate 41. The pressing plate 41 can move in both the vertical and horizontal directions. In the process of compacting the powder layer, it can simultaneously and separately realize vertical and horizontal movements to compact the powder layer, and each printing layer can be compacted during the printing process.

[0056] The present invention provides a powder layer compacting system between a powder spreading system and a negative pressure supply printing system. The powder layer compacting system includes a pressing plate. The pressing plate can compact the powder layer, especially each printing layer, and the pressing plate can move in both vertical and horizontal directions. During the compacting of the powder layer, the pressing plate can simultaneously and separately realize vertical and horizontal movements to compact the powder layer. During the printing of parts, each printing layer can be compacted, so that the density of the printed part blank is greatly improved, and it is easier to form and improve the strength to obtain a high-strength part blank. This effectively solves the problem that in the prior art of preparing part blanks with BJ equipment, the powder of each printing layer is loosely accumulated, resulting in a low density of the final printed part blank and difficulty in forming, which is also not conducive to subsequent block densification and sintering.

[0057] The powder spreading system of the 3D printing device of the present invention is mainly composed of a linear guide rail (i.e., a horizontal guide rail 7), a powder spreading roller, a servo motor, etc., and its function is to evenly spread the special powder for molding onto the molding plane.

[0058] The forming cylinder system of the 3D printing device of the present invention mainly includes a cylinder body, a piston, a guide rod, a servo motor and the like.

[0059] The cylinder system of the 3D printing device of the present invention mainly includes a cylinder body, a piston, a guide rod, a servo motor and the like.

[0060] The negative pressure ink supply printing system of the 3D printing device of the present invention mainly includes a printing nozzle and an ink supply circulation system. The ink supply circulation system mainly includes a main ink barrel, a negative pressure air pipe, an ink tube, an auxiliary ink cartridge, a control board, etc. Its function is to provide circulating adhesive for the inkjet printing system and the printing nozzle sprays a set amount of adhesive according to the program setting.

[0061] The heating system of the 3D printing device of the present invention is an infrared heating lamp, and its maximum heating power can reach 2000 W. Its function is to accelerate the curing and molding after the adhesive is sprayed, and reduce the risk of poor bonding effect between layers due to excessive humidity.

[0062] The control system of the 3D printing device of the present invention is a system with a computer as the core, which controls the nozzle to select inkjet printing on the surface of the powder bed and realizes the layer-by-layer superposition of the printing area by mechanical and electrical means. It is mainly composed of an electrical control box, an industrial computer, a PLC and other auxiliary components.

[0063] In some embodiments,

[0064] The powder layer compaction system 4 also includes a hydraulic device 42, a pressure sensor 43, an electric lifting mechanism 44 and a motor 45. The pressure sensor 43 is arranged on the pressing plate 41 to detect the pressure applied by the pressing plate 41 to the powder layer. The motor 45 is connected to the hydraulic device 42 to drive the hydraulic device 42 to operate. The hydraulic device 42 is connected to the pressing plate 41 through the electric lifting mechanism 44 to drive the pressing plate 41 to move in the vertical and horizontal directions.

[0065] The present invention uses a hydraulic device, a motor, a pressure sensor, and a motor lifting structure to drive the pressing plate to move up and down according to the pressure of the powder layer on the pressing plate, so that the pressure on the powder layer is within a required range. The pressing plate can move horizontally after compacting one layer of powder, and then compact the next powder layer, thereby achieving the effect of compacting each layer of powder. It can also compact powder layers in different areas through horizontal movement, greatly improving the density performance of the product.

[0066] The pressurizing device of the powder layer compacting system of the present invention can be a manual press or an electric press (i.e., an alternative to a hydraulic device). Furthermore, an electric press is preferred, and an electric press needs to be equipped with a motor device.

[0067] In some embodiments,

[0068] The forming cylinder system 5 includes a forming cylinder 51, the shape of the pressing plate 41 is consistent with the shape of the forming cylinder 51, the length dimension of the pressing plate 41 is M, the unit is mm, the length dimension of the forming cylinder 51 corresponding to the pressing plate 41 is N, the unit is mm, and there is the following relationship: -3≤MN≤5, preferably, -1≤MN≤2.

[0069] For example, in one feasible embodiment, the size of the forming cylinder is a rectangle with a length of 100 mm and a width of 60 mm, and the size of the corresponding pressing plate can be a length of 105 mm and a width of 65 mm, or a length of 97 mm and a width of 57 mm.

[0070] In some embodiments,

[0071] The lower surface of the pressing plate 41 is a finely polished plane, and its surface roughness value Ra is less than 1 μm, preferably Ra is less than 0.5 μm, and more preferably Ra is less than 0.2 μm.

[0072] The material of the pressing plate of the present invention is preferably metal or alloy, preferably stainless steel.

[0073] In some embodiments,

[0074] The lower surface of the pressing plate 41 is parallel to the upper surface of the forming cylinder 51 , and the angle between the two planes is less than 0.5°, preferably less than 0.2°, and more preferably less than 0.1°.

[0075] In some embodiments,

[0076] The pressure generated by the hydraulic device 42 can be adjusted within the range of 0-20 MPa.

[0077] The maximum pressure generated by the powder compaction system of the 3D printing device of the present invention can reach 20MPa. The pressure value used in the actual powder compaction is adjusted according to the actual application scenarios and operating parameters such as the printing powder material, the physicochemical properties and particle size of the powder material, and the thickness of each layer of powder during printing to achieve a better pressure parameter value.

[0078] The present invention further adjusts and optimizes the relationship between layer thickness and applied pressure, especially by ensuring that -3≤MN≤5 is satisfied between the length dimension M of the pressing plate and the corresponding length dimension N of the forming cylinder, and the pressure generated by the hydraulic device is within the range of 0-20MPa. The thickness of a single powder layer of powder laying is set at 0.08mm-0.4mm, which can further improve the density of the printed part blanks, further improve the strength of the product, and make it easier to form. The powder adhesive jet printing equipment of the present invention and the process method for printing part blanks thereof have a gain effect in terms of formability and blank density that is general and universal to various printing materials, printing shapes, printing parameters and subsequent curing and sintering processes, and the equipment modification cost is low, which greatly improves the R&D efficiency and reduces the production cost.

[0079] In some embodiments,

[0080] It also includes a horizontal guide rail 7, the powder spreading system 1 includes a powder spreading roller 11, the negative pressure ink supply printing system 3 includes a negative pressure ink supply circulation system 31 and a print nozzle 32, the negative pressure ink supply circulation system 31 can spray adhesive to the powder layer on the printing area through the print nozzle 32, the heating system 2 includes a heating lamp 21, the heating lamp 21, the powder spreading roller 11, the pressure plate 41 and the print nozzle 32 are arranged in sequence on the horizontal guide rail 7, and in the moving direction of the horizontal guide rail 7, the heating lamp 21, the powder spreading roller 11, the pressure plate 41 and the print nozzle 32 move in sequence to be opposite to the forming cylinder 51.

[0081] The moving parts of the 3D printing device of the present invention integrated on the horizontal guide rail include at least a powder spreading roller, a pressure plate, a printing nozzle and an infrared heating lamp. Furthermore, the moving parts listed above are, in the forward movement direction, the infrared heating lamp, the powder spreading roller, the pressure plate and the printing nozzle.

[0082] The binder jetting 3D printing device of the present invention, in addition to the components described above, may also include components such as a cleaning system, a moisturizing system, and a powder recovery system according to actual application requirements and scenarios.

[0083] The present invention also provides a printing method of the aforementioned powder adhesive jet printing device, comprising:

[0084] Loading and powder spreading operation: lower the height of the material cylinder from the highest limit to the preset height according to the height of the printed parts, pour the raw material powder into the material cylinder, set the powder spreading parameters and start the powder spreading action until the surface of the forming cylinder is flattened;

[0085] Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part;

[0086] The starting printing operation includes:

[0087] (1) The powder roller spreads a layer of powder on the forming cylinder;

[0088] (2) The pressing plate compacts the powder at a set pressure value, and the holding time can be set between 1s and 15s;

[0089] (3) The print head sprays the binder in the set selected area, and the spraying amount and the number of spraying scans can be adjusted according to the actual situation;

[0090] (4) The heating lamp sweeps across the molding cylinder area to accelerate the curing of the area where the adhesive has just been sprayed.

[0091] (5) The above components then return to the coordinate zero point along with the guide rail, and then continue to repeat the above steps (1)-(4) until the printing program is completed.

[0092] In some embodiments,

[0093] Before the material loading and powder spreading operations, there are steps of printing the model and powering on; between the material loading and powder spreading operations and the start of the printing operation, there is a step of setting parameters; after the start of the printing operation, there is a curing step, which forms the following steps in total:

[0094] 1) Design the 3D model of the part to be printed according to actual needs, select the printing material, set the layer thickness, and slice to generate a .cli file;

[0095] 2) Power on the printing device, run the negative pressure inkjet system, and then return all axes of the device to zero;

[0096] 3) Loading and powder spreading operation: lower the height of the material cylinder from the highest limit to the preset height according to the height of the printed parts, pour the raw material powder into the material cylinder, set the powder spreading parameters and start the powder spreading action until the surface of the forming cylinder is flattened;

[0097] 4) Import the processing file, i.e. .cli slice file, into the device computer and set the appropriate printing parameters and the powder pressing pressure value of the pressing plate;

[0098] 5) Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part;

[0099] 6) Take out the blank part and transfer it into an oven for curing at a certain temperature and insulation time to finally obtain a high-strength blank part.

[0100] In some embodiments,

[0101] The raw material powder is at least one of metal powder, ceramic powder and alloy powder; when the pressing plate is compacting the powder, the center point of the pressing plate and the center point of the forming cylinder are aligned, and the position deviation is less than ±0.3mm;

[0102] The pressure value of the pressing plate on the powder layer is selected and determined according to the substance, particle size and thickness of the powder material selected each time.

[0103] The thickness of a single powder layer is in the range of 0.08mm-0.4mm.

[0104] The present invention further increases the production cycle of part printing by setting the thickness of a single powder layer at 0.08mm-0.4mm, preferably 0.15-0.3mm. It also reduces the amount of binder used, thereby reducing production costs. Although an overly thick powder layer can compact the powder layer with a higher pressure, the binder often cannot penetrate the thicker dense powder layer, resulting in no binder bonding between thick powders, affecting the forming of the blank of the part; while a too thin powder layer will cause deformation and other effects on the underlying bonded powder layer during the compaction of the powder layer, which is prone to stress concentration between the layers of the final blank part, and then cracks and other defects. Therefore, the present invention sets it at 0.08mm-0.4mm, preferably 0.15-0.3mm, while overcoming the defects of poor bonding effect, deformation and cracks, and improving the bonding effect and preventing deformation.

[0105] The present invention provides a specific printing method and steps for powder binder jet printing of high-strength blanks, wherein the key or special steps mainly include: feeding and powder spreading operations, printing parts according to processing files, selective binder jetting, powder layer baking with a heating lamp, powder layer compaction during printing, and part blank solidification in an oven.

[0106] In one embodiment of the present invention, the printing material is powdered Si3N4 (α phase>90%, particle size D50 is about 5μm), the binder material is a self-prepared bisphenol A epoxy resin-based binder, the shape of the printed part blank is a sample strip of 80mm×35mm×20mm, the reference voltage of the negative pressure inkjet system during printing is set to 60V, the heating power of the infrared heating lamp is set to 600W, the shape of the forming cylinder in the experiment is a rectangle of 200mm×300mm, the size of the pressing plate is a rectangle of 199mm×299mm, and the pressing plate material is stainless steel; after the action of printing the part is completed, the part blank is taken out and put into an oven for curing at 150°C for 2h, and then the part blank is taken out.

[0107] Example 1

[0108] During the printing process, the pressure applied by the press plate is 5MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0109] The condition of the blank of the part prepared by printing is: good formability, relative density of 53%, precise size and no defects.

[0110] Example 2

[0111] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0112] The condition of the blank of the part prepared by printing is: good formability, relative density of 58%, precise size and no defects.

[0113] Example 3

[0114] During the printing process, the pressure applied by the press plate is 15MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0115] The condition of the blank of the part prepared by printing is: good formability, relative density of 61%, precise size and no defects.

[0116] Example 4

[0117] During the printing process, the pressure applied by the press plate is 15MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.3mm.

[0118] The condition of the blank of the part prepared by printing is: good formability, relative density of 58%, precise size and no defects.

[0119] Example 5

[0120] During the printing process, the pressure applied by the press plate is 5MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.1mm.

[0121] The condition of the blank of the part prepared by printing is: good formability, relative density of 56%, precise size and no defects.

[0122] Example 6

[0123] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 10s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0124] The condition of the blank of the part prepared by printing is: good formability, relative density of 59%, precise size and no defects.

[0125] Example 7

[0126] During the printing process, the pressure applied by the press plate is 5MPa, the holding time is 10s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.15mm.

[0127] The condition of the blank of the part prepared by printing is: good formability, relative density of 55%, precise size and no defects.

[0128] Example 8

[0129] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.5μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0130] The condition of the blank of the part prepared by printing is: good formability, relative density of 57%, precise size and no defects.

[0131] Example 9

[0132] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is 0.2°, and the thickness of each powder layer is 0.2mm.

[0133] The condition of the blank of the part prepared by printing is: good formability, relative density of 56%, precise size and no defects.

[0134] Comparative Example 1

[0135] During the printing process, no pressure is applied to the powder layer, and the thickness of each powder layer is 0.08mm.

[0136] The condition of the blank of the part prepared by printing is: poor formability, relative density of 44%, and many defects in appearance.

[0137] Comparative Example 2

[0138] During the printing process, no pressure is applied to the powder layer, and the thickness of each powder layer is 0.2mm.

[0139] The condition of the blank parts prepared by printing is: it cannot be formed and turns into powder when touched lightly.

[0140] Comparative Example 3

[0141] During the printing process, the pressure applied by the press plate is 16MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is 0.05°, and the thickness of each powder layer is 0.2mm.

[0142] The condition of the blank part prepared by printing is: good formability, relative density of 61%, outward-expanded size and many defects.

[0143] Comparative Example 4

[0144] During the printing process, the pressure applied by the press plate is 4MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0145] The condition of the blank of the part prepared by printing is: general formability, relative density of 50%, precise size and no defects.

[0146] Comparative Example 5

[0147] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 2s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0148] The condition of the blank of the part prepared by printing is: general formability, relative density of 50%, precise size and no defects.

[0149] Comparative Example 6

[0150] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is 1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.2mm.

[0151] The condition of the blank of the part prepared by printing is: good formability, relative density of 57%, and many defects in appearance.

[0152] Comparative Example 7

[0153] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is 0.6°, and the thickness of each powder layer is 0.2mm.

[0154] The condition of the blank part prepared by printing is: general formability, relative density of 53%, dimensional deformation and many defects.

[0155] Comparative Example 8

[0156] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.08mm.

[0157] The condition of the blank part prepared by printing is: good formability, relative density of 56%, dimensional deformation and many defects.

[0158] Comparative Example 9

[0159] During the printing process, the pressure applied by the press plate is 10MPa, the holding time is 5s, the roughness Ra of the press plate is <0.1μm, the parallelism deviation between the press plate and the forming cylinder is <0.05°, and the thickness of each powder layer is 0.3mm.

[0160] The condition of the blank part prepared by printing is: general formability, relative density of 53%, and outward-expanded size.

[0161] The values ​​and results of the printing parameters and the conditions of the part blanks prepared by printing in the examples 1-9 and comparative examples 1-9 listed in the present invention are shown in the following Table 1:

[0162] Table 1

[0163]

[0164]

[0165] Appendix: Evaluation criteria for formability: 0 - no formability, it will turn into powder with a slight touch; 1 - poor formability, the sample is very brittle and will break with a slight bend by hand; 2 - average formability, the sample is relatively brittle and will break with normal force; 3 - good formability, the sample is strong and will not break with normal force.

[0166] The above examples are only partial application examples of the present invention, but the present invention is not limited to the embodiments. As long as the technical effects of the present invention are achieved by any same or similar methods or process flows, they should fall within the protection scope of the present invention.

[0167] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. Any combination of the embodiments shall also be regarded as the protection scope of the present invention.

Claims

1. A powder adhesive jet printing device, characterized in that: include: A powder spreading system (1), a heating system (2), a negative pressure ink supply printing system (3), a powder layer compacting system (4), a forming cylinder system (5) and a material cylinder system (6), wherein the powder layer compacting system (4) is arranged between the powder spreading system (1) and the negative pressure ink supply printing system (3), and the powder layer compacting system (4) comprises a pressing plate (41), and the pressing plate (41) can move in both the vertical direction and the horizontal direction. During the process of compacting the powder layer, the pressing plate (41) can simultaneously and separately realize vertical and horizontal movements to compact the powder layer, and each printing layer can be compacted during the printing process.

2. The powder adhesive jet printing device according to claim 1, characterized in that: The powder layer compaction system (4) also includes a hydraulic device (42), a pressure sensor (43), an electric lifting mechanism (44) and a motor (45). The pressure sensor (43) is arranged on the pressing plate (41) to detect the pressure applied by the pressing plate (41) on the powder layer. The motor (45) is connected to the hydraulic device (42) to drive the hydraulic device (42) to operate. The hydraulic device (42) is connected to the pressing plate (41) via the electric lifting mechanism (44) to drive the pressing plate (41) to move in the vertical and horizontal directions.

3. The powder adhesive jet printing device according to claim 2, characterized in that: The molding cylinder system (5) includes a molding cylinder (51), the shape of the pressing plate (41) is consistent with the shape of the molding cylinder (51), the length dimension of the pressing plate (41) is M, the unit is mm, and the length dimension of the molding cylinder (51) corresponding to the pressing plate (41) is N, the unit is mm, and the following relationship exists: -3≤MN≤5.

4. The powder adhesive jet printing device according to claim 1, characterized in that: The lower surface of the pressing plate (41) is a finely polished plane, and its surface roughness value Ra is less than 1 μm.

5. The powder adhesive jet printing device according to claim 3, characterized in that: The lower surface of the pressing plate (41) is parallel to the upper surface of the forming cylinder (51), and the angle between the two planes is less than 0.5°.

6. The powder adhesive jet printing device according to claim 2, characterized in that: The pressure generated by the hydraulic device (42) can be adjusted within the range of 0-20 MPa.

7. The powder adhesive jet printing device according to claim 3, characterized in that: It also includes a horizontal guide rail (7), the powder spreading system (1) includes a powder spreading roller (11), the negative pressure ink supply printing system (3) includes a negative pressure ink supply circulation system (31) and a print head (32), the negative pressure ink supply circulation system (31) can spray adhesive to the powder layer on the printing area through the print head (32), the heating system (2) includes a heating lamp (21), the heating lamp (21), the powder spreading roller (11), the pressure plate (41) and the print head (32) are arranged in sequence on the horizontal guide rail (7).

8. A printing method of a powder adhesive jet printing device as claimed in any one of claims 1 to 7, characterized in that: include: Loading and powder spreading operation: lower the height of the material cylinder from the highest limit to the preset height according to the height of the printed parts, pour the raw material powder into the material cylinder, set the powder spreading parameters and start the powder spreading action until the surface of the forming cylinder is flattened; Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part; The starting printing operation includes: (1) The powder roller spreads a layer of powder on the forming cylinder; (2) The pressing plate compacts the powder at a set pressure value, and the holding time can be set between 1s and 15s; (3) The print head sprays the binder in the set selected area, and the spraying amount and the number of spraying scans can be adjusted according to the actual situation; (4) The heating lamp sweeps across the molding cylinder area to accelerate the curing of the area where the adhesive has just been sprayed. (5) The above components then return to the coordinate zero point along with the guide rail, and then continue to repeat the above steps (1)-(4) until the printing program is completed.

9. The printing method according to claim 8, characterized in that: include: Before the material loading and powder spreading operations, there are steps of printing the model and powering on; between the material loading and powder spreading operations and the start of the printing operation, there is a step of setting parameters; after the start of the printing operation, there is a curing step, which forms the following steps in total: 1) Design the 3D model of the part to be printed according to actual needs, select the printing material, set the layer thickness, and slice to generate a .cli file; 2) Power on the printing device, run the negative pressure inkjet system, and then return all axes of the device to zero; 3) Loading and powder spreading operation: lower the height of the material cylinder from the highest limit to the preset height according to the height of the printed parts, pour the raw material powder into the material cylinder, set the powder spreading parameters and start the powder spreading action until the surface of the forming cylinder is flattened; 4) Import the processing file, i.e. .cli slice file, into the device computer and set the appropriate printing parameters and the powder pressing pressure value of the pressing plate; 5) Start the printing operation. At this time, the guide rail on the equipment platform starts to move, and various printing operations are performed according to the program to print and prepare the blank of the part; 6) Take out the blank part and transfer it into an oven for curing at a certain temperature and insulation time to finally obtain a high-strength blank part.

10. The printing method according to claim 8, characterized in that: include: The raw material powder is at least one of metal powder, ceramic powder and alloy powder; when the pressing plate is compacting the powder, the center point of the pressing plate and the center point of the forming cylinder are aligned, and the position deviation is less than ±0.3mm; The pressure value of the pressing plate on the powder layer is selected and determined according to the substance, particle size and thickness of the powder material selected each time. The thickness of a single powder layer is in the range of 0.08mm-0.4mm.

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