Binder jet printing testing device and printing method

Abstract

The invention relates to a binder jet printing testing device and a printing method. The binder jet printing testing device comprises a hollow thin plate, a plurality of jet printing devices and a plurality of jet printing devices, wherein the hollow thin plate is provided with at least two positioning holes for fixing the whole hollow thin plate and at least one hollow pattern for accommodating mixed printing powder; the bottom plate is provided with a base located on the lower portion and at least two positioning rods which can penetrate through positioning holes in the hollowed-out thin plate and are used for fixing the hollowed-out thin plate. The binder spraying device is used for storing a binder for spraying printing and spraying the binder to the mixed printing powder in the hollow pattern; and the powder sweeping scraping plate is used for sweeping the residual mixed printing powder except for the hollowed-out pattern after the mixed printing powder is poured into the hollowed-out pattern.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing additive manufacturing, and in particular relates to a binder jet printing test device and a printing method. Background Art

[0002] Binder Jetting is an additive manufacturing technology that uses a binder to form powder. The principle is to use an inkjet print head to spray the binder into the powder, so that a layer of powder is bonded in the selected area. Each layer of powder is combined with the previous layer of powder through the penetration of the binder, and a three-dimensional structure is created by stacking layers. The prototype of the bonded part is degreased and sintered at high temperature to remove the binder and achieve metallurgical bonding between the powder particles to obtain a product with a certain density and strength. Binder jet 3D printing technology has the characteristics of high printing efficiency, low material cost, high cost-effective equipment, no need for additional support, and suitable for mass production.

[0003] However, currently binder jet printing equipment is relatively expensive. At the same time, a large amount of powder is required in the binder jet printing process, ranging from tens of kilograms to tons, which is not conducive to the application and promotion of binder jet forming. Summary of the invention

[0004] In view of the above technical problems, the purpose of the present invention is to provide a binder jet printing test device and a printing test method, through which the binder jet printing test can be realized. Only a small amount of powder is needed to test the printability of the powder, which is convenient and practical.

[0005] In a first aspect, the present invention provides a binder jet printing test device, comprising: A hollow thin plate, wherein the hollow thin plate is provided with at least two positioning holes for fixing the entire hollow thin plate and at least one hollow pattern for accommodating mixed printing powder; A bottom plate, the bottom plate having a base at a lower portion and at least two positioning rods capable of passing through the positioning holes on the hollow thin plate and used for fixing the hollow thin plate; a binder spraying device, the binder spraying device being used to store a binder for spray printing and spray the binder onto the mixed printing powder in the hollow pattern; and A powder cleaning scraper is used to clean the residual mixed printing powder outside the hollow pattern after the mixed printing powder is poured into the hollow pattern.

[0006] Preferably, the hollow thin plate is made of at least one of metal, acrylic plate and high molecular polymer, and the single layer thickness of the hollow thin plate is 0.1-1 mm.

[0007] Preferably, the nozzle aperture of the binder injection device is 10-100 um.

[0008] Preferably, the powder cleaning scraper is made of one or a combination of stainless steel, pure metal, acrylic plate, and high molecular polymer.

[0009] In a second aspect, the present invention provides a printing method for powder binder jet molding using the above-mentioned binder jet printing test device, comprising the following steps: (1) Mixing the printed powder to be tested with a curing agent to obtain a raw material mixed powder; (2) inserting the positioning holes of the hollow sheet into the positioning rods of the bottom plate to fix them, pouring the raw material mixed powder into and filling the hollow pattern, and using a powder cleaning scraper to remove excess raw material mixed powder around the upper hollow pattern of the hollow sheet; (3) spraying the binder evenly on the surface of the raw material mixed powder in the hollow pattern through a binder spraying device to wet the surface, and cleaning the excess binder around the raw material mixed powder after the wet process is completed; (4) according to the thickness h of the test sample and the single-layer thickness d of the hollow thin plate, the number of hollow thin plates to be repeated is calculated as n=h / d, and then the second to n-th layers of hollow thin plates are stacked and buckled on the first layer of hollow thin plate in sequence, and the process of pouring the raw material mixed powder into the hollow pattern and spraying the binder in steps (2) and (3) is repeated once for each layer of hollow thin plate, and finally a block sample of the required thickness to be tested is obtained; (5) The evaluation test of the binder jet printing performance of the tested printed powder is completed by testing the density and mechanical properties of the binder jet block sample and the microstructure after molding.

[0010] Preferably, in step (1), the printed powder to be tested includes metal powder, ceramic powder or organic powder; wherein the metal powder includes stainless steel powder, titanium alloy powder, copper alloy powder, tantalum tungsten high temperature alloy powder; the ceramic powder includes alumina powder, zirconium oxide powder, silicon nitride powder, silicon carbide powder, boron carbide powder, carbon fiber graphite powder, silica powder, cordierite powder, silica sand powder; the organic powder includes polylactic acid, polyethylene glycol, acrylonitrile-butadiene-styrene terpolymer, thermoplastic polyurethane elastomer rubber, polycarbonate, polyvinyl alcohol powder.

[0011] Preferably, in step (1), the curing agent comprises dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzenesulfonic acid or phenolsulfonic acid, preferably benzenesulfonic acid or phenolsulfonic acid, more preferably p-toluenesulfonic acid.

[0012] Preferably, in step (1), the content of the curing agent is 0.8-2wt% of the mass of the printed powder to be tested, and the time for mixing the printed powder to be tested and the curing agent is 30-120s.

[0013] Preferably, in step (3), the binder includes at least one of phenolic resin, furan resin, polyimide, polyvinyl pyrrolidone, cellulose, starch, sugar, silicate, silicon-containing polymer, water glass, asphalt and polyacrylonitrile.

[0014] Preferably, in step (3), the infiltration time is 30-60s.

[0015] Beneficial Effects The binder jet printing test device provided by the present invention can realize the test of binder jet printing, and only a small amount of powder is needed to test the printability and formability of the powder, which is convenient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the hollow thin plate structure of the present invention; Figure 2 This is a schematic structural diagram of a bottom plate with a positioning rod and a state where the bottom plate is fixed to a hollow thin plate according to an example of the present invention; Reference numerals: 1, 2-positioning hole, 3-hollow pattern, 4-hollow thin plate, 5, 6-positioning rod, 7-bottom plate. DETAILED DESCRIPTION

[0017] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0018] First, combine Figure 1 , 2 , an exemplary binder jet printing test device provided by the present invention. Wherein, the binder jet printing test device may include: A hollow sheet 4, on which at least two positioning holes 1, 2 for fixing the entire hollow sheet 4 and at least one hollow pattern 3 for accommodating mixed printing powder are arranged; A bottom plate 7, the bottom plate 7 having a base at the bottom and at least two positioning rods 5, 6 that can pass through the positioning holes on the hollow thin plate 4 and are used to fix the hollow thin plate 4; A binder spraying device (not shown in the figure), the binder spraying device is used to store a binder for spray printing and spray the binder onto the mixed printing powder in the hollow pattern 3; and, A powder cleaning scraper (not shown in the figure) is used to clean the residual mixed printing powder outside the hollow pattern 3 after the mixed printing powder is poured into the hollow pattern 3.

[0019] In some embodiments, the hollow thin plate 4 may be made of at least one of metal, acrylic plate, and high molecular polymer; wherein the metal may be stainless steel.

[0020] In some embodiments, the single layer thickness of the hollow thin plate 4 may be 0.1-1 mm. The number of the hollow thin plates 4 may be determined according to the thickness of the sample to be printed and the thickness of the hollow thin plates 4. If the single layer thickness of the hollow thin plate 4 is too small, the printing process will be difficult to carry out; if the single layer thickness is too large, the packing density of the printed powder will be reduced.

[0021] In some embodiments, the shape of the hollow pattern 3 may include a five-pointed star or a polygon.

[0022] In some embodiments, the nozzle aperture of the binder injection device can be controlled within the range of 10-100um. The flow rate of the binder injection device can be controlled by adjusting the valve to control the gas pressure, and the pressure is provided by the air compressor; in addition, the binder injection can also be achieved by manually controlling the binder flow rate through a pneumatic spray pot. If the nozzle aperture is too large, the atomization effect cannot be formed; if the nozzle aperture is too small, the binder content will be low.

[0023] In some embodiments, the powder cleaning scraper may be made of one or a combination of stainless steel, pure metal, acrylic plate, and high molecular polymer.

[0024] The binder jet printing test device provided by the present invention can realize the test of binder jet printing, and only a small amount of powder is needed to test the printability and formability of the powder, which is convenient and practical.

[0025] The following is an exemplary description of a printing method for powder binder jet molding using the above-mentioned binder jet printing test device. The printing method may include the following steps: (1) Mixing the printed powder to be tested with a curing agent to obtain a raw material mixed powder; (2) inserting the positioning holes of the hollow sheet 4 into the positioning rods 5 and 6 of the bottom plate 7 to fix them, pouring the raw material mixed powder into and filling the hollow pattern 3, and using a powder cleaning scraper to remove excess raw material mixed powder around the hollow pattern 3 on the hollow sheet 4; (3) using a binder spraying device to evenly spray the binder on the surface of the raw material mixed powder in the hollow pattern 3 and infiltrate it, and after the infiltration is completed, clean up the excess binder around the raw material mixed powder; (4) according to the thickness h of the test sample and the single-layer thickness d of the hollow thin plate 4, the number of hollow thin plates 4 to be repeated is calculated as n=h / d, and then the second to n-th layers of hollow thin plates are stacked and buckled on the first layer of hollow thin plates in sequence, and the process of pouring the raw material mixed powder into the hollow pattern 3 and spraying the binder in steps (2) and (3) is repeated once for each layer of hollow thin plates stacked and buckled, and finally a block sample of the required thickness to be tested is obtained; (5) The evaluation test of the binder jet printing performance of the tested printed powder is completed by testing the density and mechanical properties of the binder jet block sample and the microstructure after molding.

[0026] In some embodiments, in step (1), the printed powder to be tested may include metal powder, ceramic powder or organic powder; wherein the metal powder may include stainless steel powder, titanium alloy powder, copper alloy powder, tantalum tungsten high temperature alloy powder; the ceramic powder may include alumina powder, zirconium oxide powder, silicon nitride powder, silicon carbide powder, boron carbide powder, carbon fiber graphite powder, silica powder, cordierite powder, silica sand powder; the organic powder may include PLA (polylactic acid), PEG (polyethylene glycol), ABS (acrylonitrile-butadiene-styrene terpolymer), TPU (thermoplastic polyurethane elastomer rubber), PC (polycarbonate), PVA (polyvinyl alcohol) powder.

[0027] In some embodiments, in step (1), the curing agent may include dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzenesulfonic acid or phenolsulfonic acid, preferably benzenesulfonic acid or phenolsulfonic acid, more preferably p-toluenesulfonic acid.

[0028] In some embodiments, in step (1), the content of the curing agent may be 0.8-2 wt % of the mass of the printed powder to be tested, and the time for mixing the printed powder to be tested and the curing agent may be 30-120 s.

[0029] In some embodiments, in step (3), the binder may include at least one of phenolic resin, furan resin, polyimide, polyvinyl pyrrolidone, cellulose, starch, sugar, silicate, silicon-containing polymer, water glass, asphalt, and polyacrylonitrile (PAN).

[0030] In some embodiments, in step (3), the soaking time may be 30-60 seconds, so that the raw material mixed powder is fully solidified.

[0031] In some embodiments, the bending strength of the printed sample can reach 15 MPa. The method provided by the present invention is also applicable to preparing samples of various shapes by selective laser sintering (SLS).

[0032] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all belong to the scope of protection of the present invention. The specific process parameters of the following examples are also only examples within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description of this article, and are not limited to the specific values ​​​​exemplified below. If not specifically stated, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0033] Example 1

[0034] The printing test method for powder binder jet molding using the binder jet printing test device provided in this embodiment includes the following steps: (1) Mixing the silicon carbide powder to be tested with good fluidity and a citric acid curing agent, wherein the content of the curing agent is 1wt% of the mass of the silicon carbide powder, and the mixing time is 30s to obtain a raw material mixed powder; (2) Place a 0.5 mm thick stainless steel sheet flat on the bottom plate, pour the powder mixed with the curing agent into the hollow pattern to ensure that the hollow pattern can be filled, use a scraper to keep close contact with the sheet and gently push it flat to ensure that the excess powder is not in the hollow pattern and remove it; (3) Spray the phenolic resin binder evenly on the surface of the hollow pattern powder through a 50 μm pneumatic nozzle, wait for 60 seconds, and clean the excess binder on the thin plate; (4) Put a second stainless steel sheet of the same thickness on top of the first sheet to ensure that the two sheets are in close contact. Pour the powder mixed with the curing agent into the hollow pattern to ensure that the hollow pattern can be filled. Use a stainless steel scraper to keep close contact with the stainless steel sheet and gently push it flat to ensure that the excess powder is not in the hollow pattern and is removed. Spray the binder evenly on the surface of the powder in the hollow pattern through a pneumatic nozzle with an aperture of 50um, wait for 60s, and clean the excess binder on the sheet. According to the sample thickness of 5mm and the sheet thickness of 0.5mm, set the number of thin plate n = 10, repeat the above printing steps for a total of 8 times, and finally obtain the required block sample with a thickness of 5mm to be tested; (5) The density and flexural strength of the bulk silicon carbide samples were tested to evaluate the performance of the binder jet printing of the printed powder to be tested, providing guidance for subsequent experiments.

[0035] Example 2

[0036] The printing test method for powder binder jet molding using the binder jet printing test device provided in this embodiment includes the following steps: (1) mixing silica sand powder with good fluidity with a benzenesulfonic acid curing agent, wherein the content of the curing agent is 1.5wt% of the silica sand powder, and the mixing time is 40s to obtain a raw material mixed powder; (2) Place a 1 mm thick acrylic sheet on the base plate, pour silica sand powder mixed with curing agent into the hollow pattern to ensure that the hollow pattern can be filled, and use a stainless steel scraper to closely contact the acrylic sheet and gently push it flat to ensure that the excess powder is not in the hollow pattern and remove it; (3) Spray the furan resin binder evenly on the surface of the hollow pattern powder through a pneumatic nozzle with an aperture of 40 μm, wait for 30 seconds, and clean the excess binder on the thin plate; (4) Put the second thin plate on the first thin plate to ensure that the two thin plates are in close contact. Similarly, pour the silica sand powder mixed with the curing agent into the hollow pattern to ensure that the hollow pattern can be filled. Use a stainless steel scraper to closely contact the acrylic thin plate and gently push it flat to ensure that the excess powder is not in the hollow pattern and is removed; spray the furan resin binder evenly on the powder surface of the hollow pattern through a pneumatic nozzle with an aperture of 40um, wait for 30 seconds, and clean the excess binder on the thin plate; according to the sample thickness of 10mm and the thickness of the thin plate of 1mm, set the number of thin plate n=10, repeat the above printing steps for a total of 8 times, and finally obtain the required block sample with a thickness of 10mm to be tested; (5) By testing the material properties of the silica sand block sample, such as density and flexural strength, the evaluation test of the binder jet printing performance of the tested printing powder is completed, providing guidance for subsequent experiments.

[0037] Example 3

[0038] The printing test method for powder binder jet molding using the binder jet printing test device provided in this embodiment includes the following steps: (1) mixing Ta10W high temperature alloy powder with good fluidity with phosphoric acid + citric acid curing agent, wherein the content of the curing agent is 2wt% of the Ta10W high temperature alloy powder, and the mixing time is 60s to obtain a raw material mixed powder; (2) Place a 0.5 mm thick stainless steel sheet on the bottom plate, pour the powder mixed with the curing agent into the hollow pattern to ensure that the hollow pattern can be filled, and use an acrylic scraper to closely contact the stainless steel sheet and gently push it flat to ensure that the excess powder is not in the hollow pattern and remove it; (3) Spray the polyvinyl pyrrolidone binder evenly on the surface of the hollowed-out Ta10W powder through a 50 μm pneumatic nozzle, wait for 60 seconds, and clean the excess binder on the thin plate; (4) Put the second thin plate on the first thin plate to ensure that the two thin plates are in close contact. Pour the powder mixed with phosphoric acid + citric acid curing agent into the hollow pattern to ensure that the hollow pattern can be filled. Use an acrylic scraper to contact the stainless steel thin plate closely and gently push it flat to ensure that the excess powder is not in the hollow pattern and is removed; spray the polyvinyl pyrrolidone binder evenly on the powder surface of the hollow pattern through a pneumatic nozzle with an aperture of 50um, wait for 60s, and clean the excess binder on the thin plate; according to the sample thickness of 6mm and the thickness of the thin plate of 0.3mm, set the number of thin plate n = 20, repeat the above printing steps for a total of 18 times, and finally obtain the required block sample with a thickness of 6mm to be tested; (5) The density and flexural strength of the block samples were tested to evaluate the performance of the binder jet printing of the printed powder to be tested, providing guidance for subsequent experiments.

[0039] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A binder jet printing test device, characterized in that: include: A hollow thin plate, wherein the hollow thin plate is provided with at least two positioning holes for fixing the entire hollow thin plate and at least one hollow pattern for accommodating mixed printing powder; A bottom plate, the bottom plate having a base at a lower portion and at least two positioning rods capable of passing through the positioning holes on the hollow thin plate and used for fixing the hollow thin plate; A binder spraying device, the binder spraying device is used to store a binder for spray printing and spray the binder onto the mixed printing powder in the hollow pattern; as well as, A powder cleaning scraper is used to clean the residual mixed printing powder outside the hollow pattern after the mixed printing powder is poured into the hollow pattern.

2. The binder jet printing test device according to claim 1, characterized in that: The hollow thin plate is made of at least one of metal, acrylic plate and high molecular polymer, and the single layer thickness of the hollow thin plate is 0.1-1 mm.

3. The binder jet printing test device according to claim 1 or 2, characterized in that: The nozzle aperture of the binder injection device is 10-100um.

4. The binder jet printing test device according to any one of claims 1 to 3, characterized in that: The powder cleaning scraper is made of one or a combination of stainless steel, pure metal, acrylic plate, and high molecular polymer.

5. A printing method for powder binder jet molding using the binder jet printing test device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Mixing the printed powder to be tested with a curing agent to obtain a raw material mixed powder; (2) inserting the positioning holes of the hollow sheet into the positioning rods of the bottom plate to fix them, pouring the raw material mixed powder into and filling the hollow pattern, and using a powder cleaning scraper to remove excess raw material mixed powder around the upper hollow pattern of the hollow sheet; (3) spraying the binder evenly on the surface of the raw material mixed powder in the hollow pattern through a binder spraying device to wet the surface, and cleaning the excess binder around the raw material mixed powder after the wet process is completed; (4) according to the thickness h of the test sample and the single-layer thickness d of the hollow thin plate, the number of hollow thin plates to be repeated is calculated as n=h / d, and then the second to n-th layers of hollow thin plates are stacked and buckled on the first layer of hollow thin plate in sequence, and the process of pouring the raw material mixed powder into the hollow pattern and spraying the binder in steps (2) and (3) is repeated once for each layer of hollow thin plate, and finally a block sample of the required thickness to be tested is obtained; (5) The evaluation test of the binder jet printing performance of the tested printed powder is completed by testing the density and mechanical properties of the binder jet block sample and the microstructure after molding.

6. The printing method according to claim 5, characterized in that: In step (1), the printed powder to be tested includes metal powder, ceramic powder or organic powder; wherein the metal powder includes stainless steel powder, titanium alloy powder, copper alloy powder, tantalum tungsten high temperature alloy powder; the ceramic powder includes alumina powder, zirconium oxide powder, silicon nitride powder, silicon carbide powder, boron carbide powder, carbon fiber graphite powder, silicon dioxide powder, cordierite powder, silica sand powder; the organic powder includes polylactic acid, polyethylene glycol, acrylonitrile-butadiene-styrene terpolymer, thermoplastic polyurethane elastomer rubber, polycarbonate, polyvinyl alcohol powder.

7. The printing method according to claim 5 or 6, characterized in that: In step (1), the curing agent includes dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzenesulfonic acid or phenolsulfonic acid, preferably benzenesulfonic acid or phenolsulfonic acid, more preferably p-toluenesulfonic acid.

8. The printing method according to any one of claims 5 to 7, characterized in that: In step (1), the content of the curing agent is 0.8-2wt% of the mass of the printed powder to be tested, and the time for mixing the printed powder to be tested and the curing agent is 30-120s.

9. The printing method according to any one of claims 5 to 8, characterized in that: In step (3), the binder includes at least one of phenolic resin, furan resin, polyimide, polyvinyl pyrrolidone, cellulose, starch, sugar, silicate, silicon-containing polymer, water glass, asphalt, and polyacrylonitrile.

10. The printing method according to any one of claims 5 to 9, characterized in that: In step (3), the infiltration time is 30-60s.

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