A binder jet printing test device and method

Abstract

The present invention relates to a binder jet printing test device and a printing method. The binder jet printing test device includes a perforated sheet having at least two positioning holes for fixing the entire perforated sheet and at least one perforated pattern for accommodating mixed printing powder, a base plate having a base at a lower portion and at least two positioning rods capable of passing through the positioning holes of the perforated sheet and for fixing the perforated sheet, a binder jet device for storing a binder for jet printing and jetting the binder onto the mixed printing powder in the perforated pattern, and a powder cleaning blade for cleaning residual mixed printing powder outside the perforated pattern after the mixed printing powder is poured into the perforated pattern.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of 3D printing additive manufacturing technology, and particularly relates to a binder jetting printing test device and a printing method. BACKGROUND

[0002] Binder jetting is an additive manufacturing technology that forms a powder by jetting a binder. The principle is to use an inkjet printhead to spray a binder into the powder, thereby bonding a layer of powder in the selected area. Each layer of powder is combined with the previous powder layer through the penetration of the binder, and thus the three-dimensional structure of the object is manufactured layer by layer. The binder-jetted prototype is debound and sintered at high temperature to remove the binder and achieve metallurgical bonding between the powder particles, resulting in a product with certain density and strength. Binder jetting 3D printing technology has the characteristics of high printing efficiency, low material cost, high cost performance of equipment, no need for additional support, and suitability for batch production.

[0003] However, the current binder jetting printing equipment is relatively expensive, and a large amount of powder is required during the binder jetting printing process, ranging from tens of kilograms to several tons, which is not conducive to the application and promotion of binder jetting forming. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide a binder jetting printing test device and a printing test method. The device can test binder jetting printing, and only a small amount of powder is required to test the printability of the powder, which is convenient and practical.

[0005] In a first aspect, the present application provides a binder jetting printing test device, comprising:

[0006] A hollow thin plate, at least two positioning holes for fixing the entire hollow thin plate and at least one hollow pattern for accommodating mixed printing powder are arranged on the hollow thin plate;

[0007] A bottom plate having a base at the lower part 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;

[0008] A binder jetting device for storing binder for jet printing and jetting binder onto the mixed printing powder in the hollow pattern; and

[0009] A powder cleaning scraper for cleaning residual mixed printing powder outside the hollow pattern after the mixed printing powder is poured into the hollow pattern.

[0010] Preferably, the material of the hollow sheet is at least one of metal, acrylic plate, and high polymer, and the thickness of a single layer of the hollow sheet is 0.1-1mm.

[0011] Preferably, the nozzle aperture size of the binder jetting device is 10-100um.

[0012] Preferably, the material of the powder cleaning scraper is one or a combination of stainless steel, pure metal, acrylic plate, and high polymer.

[0013] In a second aspect, the present application provides a printing method for powder binder jetting molding using the above-mentioned binder jetting printing test device, comprising the following steps:

[0014] (1) mixing the printing powder to be tested with a curing agent to obtain a raw material mixed powder;

[0015] (2) fixing the positioning hole of the hollow sheet to the positioning rod of the bottom plate, pouring the raw material mixed powder into the hollow pattern and filling it, and removing the excess raw material mixed powder around the upper hollow pattern of the hollow sheet with the powder cleaning scraper;

[0016] (3) uniformly spraying the binder on the surface of the raw material mixed powder in the hollow pattern with the binder jetting device and performing infiltration, and then cleaning the excess binder around the periphery of the raw material mixed powder after the infiltration is completed;

[0017] (4) calculating the number of repeated hollow sheets n = h / d according to the required sample thickness h and the thickness d of a single layer of the hollow sheet, and then sequentially stacking and pressing the second to n layers of hollow sheets on the first layer of hollow sheet, and repeating the process of pouring the raw material mixed powder into the hollow pattern and spraying the binder in steps (2) and (3) for each layer of hollow sheet, to finally obtain the block sample with the required thickness to be tested;

[0018] (5) evaluating and testing the binder jetting printing performance of the printing powder to be tested by testing the density and mechanical properties of the binder jetting block sample and the microstructure after molding.

[0019] Preferably, in step (1), the printing powder to be tested includes metal powder, ceramic powder, or organic powder; the metal powder includes stainless steel powder, titanium alloy powder, copper alloy powder, and tantalum-tungsten high-temperature alloy powder; the ceramic powder includes alumina powder, zirconia powder, silicon nitride powder, silicon carbide powder, boron carbide powder, carbon fiber graphite powder, silica powder, cordierite powder, and silica sand powder; and the organic powder includes polylactic acid, polyethylene glycol, acrylonitrile-butadiene-styrene terpolymer, thermoplastic polyurethane elastomer rubber, polycarbonate, and polyvinyl alcohol powder.

[0020] Preferably, in step (1), the solidifying agent comprises dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzene sulfonic acid or phenol sulfonic acid, preferably benzene sulfonic acid or phenol sulfonic acid, and more preferably p-toluene sulfonic acid.

[0021] Preferably, in step (1), the content of the solidifying agent is 0.8-2wt% of the mass of the printing powder to be tested, and the mixing time of the printing powder to be tested with the solidifying agent is 30-120s.

[0022] Preferably, in step (3), the binder comprises at least one of phenolic resin, furan resin, polyimide, polyvinylpyrrolidone, cellulose, starch, sugar, silicate, silicon-containing polymer, water glass, asphalt, polyacrylonitrile.

[0023] Preferably, in step (3), the infiltration time is 30-60s.

[0024] Advantages

[0025] The binder jet printing test device provided by the present application can realize the test of binder jet printing, and only a small amount of powder is needed to test the printability of the powder, which is convenient and practical. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A schematic diagram of a hollow thin plate structure according to an example of the present application;

[0027] Figure 2 A schematic diagram of a base plate with positioning rods and its fixed state with a hollow thin plate according to an example of the present application;

[0028] Reference signs:

[0029] 1, 2 - positioning holes, 3 - hollow pattern, 4 - hollow thin plate, 5, 6 - positioning rods, 7 - base plate. DETAILED DESCRIPTION

[0030] The present application will be further described below by the following embodiments, which should be understood as merely illustrative of the present application, but not limiting the present application.

[0031] First, in combination with Figure 1 , 2 , an example of the binder jet printing test device provided by the present application is shown. The binder jet printing test device can comprise:

[0032] A hollow thin plate 4, at least two positioning holes 1, 2 for fixing the entire hollow thin plate 4 and at least one hollow pattern 3 for accommodating mixed printing powder are arranged on the hollow thin plate 4;

[0033] A bottom plate 7 having a base at the lower part and at least two positioning rods 5, 6 capable of passing through the positioning holes on the hollow sheet 4 and used for fixing the hollow sheet 4;

[0034] A binder spraying device (not shown in the figure) used to store the binder for spraying printing and spray the binder on the mixed printing powder in the hollow pattern 3; and

[0035] A powder cleaning scraper (not shown in the figure) 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.

[0036] In some embodiments, the material of the hollow sheet 4 can be at least one of metal, acrylic sheet, and high polymer; wherein the metal can be stainless steel.

[0037] In some embodiments, the single-layer thickness of the hollow sheet 4 can be 0.1-1mm. The number of the hollow sheet 4 can be determined according to the thickness of the sample to be printed and its own thickness. Wherein, the single-layer thickness of the hollow sheet 4 is too small, which will cause the printing process difficult to proceed; the single-layer thickness is too large, which will cause the bulk density of the printing powder to be reduced.

[0038] In some embodiments, the shape of the hollow pattern 3 can include a pentagram, a polygon.

[0039] In some embodiments, the nozzle aperture size of the binder spraying device can be controlled to be 10-100um. Wherein, the flow size of the binder spraying 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 spraying can also be manually controlled by the gas pressure type spray pot to realize the binder spraying. The nozzle aperture size is too large, which cannot form the atomization effect; the nozzle aperture size is too small, which will cause the binder content to be low.

[0040] In some embodiments, the material of the powder cleaning scraper can be one or a combination of several materials such as stainless steel, pure metal, acrylic sheet, and high polymer.

[0041] The binder spraying printing test device provided by the present application can realize the test of binder spraying printing, and only a small amount of powder is needed to test the printability of the powder, which is convenient and practical.

[0042] Hereinafter, the printing method of powder binder spraying forming by using the above-mentioned binder spraying printing test device is exemplarily described. Wherein, the printing method can include the following steps:

[0043] (1) Mix the printing powder to be tested with the curing agent to obtain a raw material mixed powder;

[0044] (2) Fix the positioning holes of the hollow sheet 4 to the positioning rods 5, 6 of the bottom plate 7, pour the raw material mixed powder into and fill the hollow pattern 3, and remove the excess raw material mixed powder around the hollow pattern 3 on the hollow sheet 4 with a powder cleaning scraper;

[0045] (3) Uniformly spray the binder on the surface of the raw material mixed powder in the hollow pattern 3 through a binder spraying device and perform infiltration, and clean the excess binder on the periphery of the raw material mixed powder after the infiltration is completed;

[0046] (4) Calculate the number of blocks n of the hollow sheet 4 required to be repeated according to the thickness h of the sample to be tested and the single-layer thickness d of the hollow sheet 4, and then stack and press the second to n layers of hollow sheets on the first layer of hollow sheet in turn, and repeat the process of pouring the raw material mixed powder into the hollow pattern 3 and spraying the binder in steps (2) and (3) for each layer of hollow sheet stacked and pressed, and finally obtain the block sample of the required thickness to be tested;

[0047] (5) Complete the evaluation test of the binder jet printing performance of the printing powder to be tested by testing the density and mechanical properties of the binder jet block sample and the microstructure after forming.

[0048] In some embodiments, in step (1), the printing powder to be tested can include metal powder, ceramic powder or organic powder; wherein the metal powder can include stainless steel powder, titanium alloy powder, copper alloy powder, tantalum-tungsten high-temperature alloy powder, the ceramic powder can include alumina powder, zirconia powder, silicon nitride powder, silicon carbide powder, boron carbide powder, carbon fiber graphite powder, silicon dioxide powder, cordierite powder, silica sand powder, and the organic powder can include PLA (polylactic acid), PEG (polyethylene glycol), ABS (acrylonitrile-butadiene-styrene terpolymer), TPU (thermoplastic polyurethane elastomer rubber), PC (polycarbonate), and PVA (polyvinyl alcohol) powder.

[0049] In some embodiments, in step (1), the curing agent can include dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzene sulfonic acid or phenol sulfonic acid, preferably benzene sulfonic acid or phenol sulfonic acid, and more preferably p-toluene sulfonic acid.

[0050] In some embodiments, in step (1), the content of the curing agent can be 0.8-2wt% of the mass of the printing powder to be tested, and the mixing time of the printing powder to be tested with the curing agent can be 30-120s.

[0051] In some embodiments, in step (3), the binder can include at least one of phenolic resin, furan resin, polyimide, polyvinylpyrrolidone, cellulose, starch, sugar, silicate, silicon-containing polymer, water glass, pitch, polyacrylonitrile (PAN).

[0052] In some embodiments, in step (3), the infiltration time can be 30-60s. Thus, the raw material mixed powder is fully solidified.

[0053] In some embodiments, the bending strength of the printed sample after printing can reach 15MPa. The method provided by the present application is also suitable for preparing various shaped samples by laser selective sintering (SLS) method.

[0054] The following further illustrates examples to explain the present application in detail. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can make appropriate selection within the range through the description herein, and are not limited to the specific values of the following examples. If not specified, the technical means used in the examples are the conventional means known to those skilled in the art.

[0055] Example 1

[0056] The printing test method for powder binder jet molding provided by the present embodiment using the test device for printing with the binder includes the following steps:

[0057] (1) Mix the testable printing silicon carbide powder with good fluidity with a citric acid curing agent, the content of the curing agent being 1wt% of the mass of the silicon carbide powder, and the mixing time being 30s, to obtain a raw material mixed powder;

[0058] (2) Place a 0.5mm thick stainless steel sheet on the bottom plate, pour the mixed powder with the curing agent into the hollow pattern, ensure that the hollow pattern can be filled, and use a scraper to make close contact with the sheet and gently push it to ensure that the excess powder is not in the hollow pattern and is removed;

[0059] (3) uniformly spray phenolic resin binder on the surface of the powder in the hollow pattern through a pneumatic nozzle with a pore size of 50um, wait for 60s, and clean the excess binder on the sheet;

[0060] (4) Put the second layer of stainless steel sheet on the first layer of sheet, ensure that the two layers of sheet are in close contact, and pour the mixed and cured powder into the hollow pattern, ensure that the hollow pattern can be filled, and use the stainless steel scraper to make close contact with the stainless steel sheet and gently push it, ensure that the excess powder is not in the hollow pattern and is removed; evenly spray the binder through the 50um aperture pneumatic nozzle on the surface of the powder in the hollow pattern, 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 sheet number n = 10, repeat the above printing steps for 8 times, and finally get the block sample with the required thickness of 5mm;

[0061] (5) Through the test, the density and bending strength of the block silicon carbide sample are obtained, and the evaluation test of the binder injection printing performance of the test powder is completed, which provides guidance for subsequent experiments.

[0062] Example 2

[0063] The printing test method for powder binder injection molding provided by the embodiment includes the following steps:

[0064] (1) Mix the silicon sand powder with good fluidity with the benzenesulfonic acid curing agent, the content of the curing agent is 1.5wt% of the silicon sand powder, and the mixing time is 40s, to obtain the raw material mixed powder;

[0065] (2) Put the 1mm thick acrylic sheet on the bottom plate, pour the mixed and cured silicon sand powder into the hollow pattern, ensure that the hollow pattern can be filled, and use the stainless steel scraper to make close contact with the acrylic sheet and gently push it, ensure that the excess powder is not in the hollow pattern and is removed;

[0066] (3) Evenly spray the furan resin binder through the 40um aperture pneumatic nozzle on the surface of the powder in the hollow pattern, wait for 30s, and clean the excess binder on the sheet;

[0067] (4) Put the second layer of sheet on the first layer of sheet, ensure that the two layers of sheet are in close contact, and pour the mixed and cured silicon sand powder into the hollow pattern, ensure that the hollow pattern can be filled, and use the stainless steel scraper to make close contact with the acrylic sheet and gently push it, ensure that the excess powder is not in the hollow pattern and is removed; evenly spray the furan resin binder through the 40um aperture pneumatic nozzle on the surface of the powder in the hollow pattern, wait for 30s, and clean the excess binder on the sheet; according to the sample thickness of 10mm and the sheet thickness of 1mm, set the sheet number n = 10, repeat the above printing steps for 8 times, and finally get the block sample with the required thickness of 10mm;

[0068] (5) Through the density and bending strength of the obtained silicon sand block sample, the evaluation test of the printing powder binder jet printing performance to be tested is completed, and guidance is provided for subsequent experiments.

[0069] Embodiment 3

[0070] The printing test method for powder binder jet forming provided by the embodiment includes the following steps:

[0071] (1) Mix the Ta10W high-temperature alloy powder with good fluidity with the phosphoric acid + citric acid curing agent, the content of the curing agent is 2wt% of the Ta10W high-temperature alloy powder, and the mixing time is 60s, to obtain the raw material mixed powder;

[0072] (2) Place a 0.5mm thick stainless steel sheet on the bottom plate, pour the mixed powder with the curing agent into the hollow pattern, ensure that the hollow pattern can be filled, and use the acrylic scraper to tightly contact the stainless steel sheet and gently push it, to ensure that the excess powder is not in the hollow pattern and is removed;

[0073] (3) Uniformly spray polyvinylpyrrolidone binder on the surface of the Ta10W powder in the hollow pattern through a 50um aperture pneumatic nozzle, wait for 60s, and clean the excess binder on the sheet;

[0074] (4) Put the second layer of sheet on the first layer of sheet to ensure that the two layers of sheet are in close contact, pour the mixed powder with the phosphoric acid + citric acid curing agent into the hollow pattern, ensure that the hollow pattern can be filled, and use the acrylic scraper to tightly contact the stainless steel sheet and gently push it, to ensure that the excess powder is not in the hollow pattern and is removed; uniformly spray polyvinylpyrrolidone binder on the surface of the powder in the hollow pattern through a 50um aperture pneumatic nozzle, wait for 60s, and clean the excess binder on the sheet; according to the sample thickness of 6mm and the sheet thickness of 0.3mm, set the number of sheets n = 20, repeat the above printing steps for a total of 18 times, and finally obtain the block sample with a required thickness of 6mm to be tested;

[0075] (5) Through the density and bending strength of the obtained silicon sand block sample, the evaluation test of the printing powder binder jet printing performance to be tested is completed, and guidance is provided for subsequent experiments.

[0076] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present application. After reading the above content, various modifications and alternatives of the present application will be obvious to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A binder jet printing test device, characterized in that: include: A certain number of hollow sheets, wherein the number n is determined based on the thickness h of the test sample and the thickness d of the single layer of the hollow sheet: n = h / d, and the hollow sheet is provided with at least two positioning holes for fixing the entire hollow sheet and at least one hollow pattern for accommodating the mixed printing powder; A 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 to fix 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; as well as, A powder cleaning scraper is used to clean 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 and high molecular polymer, and the thickness of a single layer 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 adhesive injection device is 10-100 μm.

4. The binder jet printing test device according to claim 1 or 2, characterized in that: The powder cleaning scraper is made of one or a combination of stainless steel, pure metal, and high molecular polymer.

5. A method for performing a printing test of 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 printing powder to be tested with a curing agent to obtain a mixed printing powder; (2) Insert the positioning holes of the hollow sheet into the positioning rods of the bottom plate to fix it, pour the mixed printing powder into and fill the hollow pattern, and use a powder cleaning scraper to remove excess mixed printing powder around the hollow pattern on the hollow sheet; (3) The binder is evenly sprayed on the surface of the mixed printing powder in the hollow pattern through the binder spraying device and infiltrated. After the infiltration is completed, the excess binder around the mixed printing powder is cleaned; (4) Calculate the number of hollowed-out thin plates n = h / d that need to be repeated based on the thickness h of the test sample and the thickness d of the single layer of the hollowed-out thin plate, and then stack and buckle the second to n layers of hollowed-out thin plates on the first layer of hollowed-out thin plate in sequence. Repeat the process of pouring the mixed printing powder into the hollowed-out pattern and spraying the adhesive in steps (2) and (3) for each layer of hollowed-out thin plate stacked and buckled, and finally obtain a block sample to be tested of the required thickness; (5) By testing the density and mechanical properties of the block sample and the microstructure after molding, the evaluation test of the binder jet printing performance of the tested printing powder is completed.

6. The printing test method according to claim 5, characterized in that: In step (1), the printing powder to be tested is selected from metal powder, ceramic powder or organic powder; wherein the metal powder is selected from stainless steel powder, titanium alloy powder, copper alloy powder, tantalum-tungsten high-temperature alloy powder, the ceramic powder is selected from 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, and the organic powder is selected from polylactic acid, polyethylene glycol, acrylonitrile-butadiene-styrene terpolymer, thermoplastic polyurethane elastomer, polycarbonate, and polyvinyl alcohol.

7. The printing test method according to claim 5, characterized in that: In step (1), the curing agent is selected from dilute sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid, maleic anhydride, citric acid, malic acid, benzenesulfonic acid or phenolsulfonic acid.

8. The printing test method according to claim 7, characterized in that: In step (1), the curing agent is benzenesulfonic acid or phenolsulfonic acid.

9. The printing test method according to claim 7, characterized in that: In step (1), the curing agent is p-toluenesulfonic acid.

10. The printing test method according to claim 5, characterized in that: In step (1), the content of the curing agent is 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 is 30-120 s.

11. The printing test method according to claim 5, characterized in that: In step (3), the binder is selected from at least one of phenolic resin, furan resin, polyimide, polyvinyl pyrrolidone, cellulose, starch, silicate, silicon-containing polymer, asphalt, and polyacrylonitrile.

12. The printing test method according to claim 5, characterized in that: In step (3), the infiltration time is 30-60s.

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