Supporting method and supporting device for 3D printing sintering

Abstract

The invention relates to the technical field of 3D printing, and particularly discloses a supporting method and device for 3D printing sintering, and the supporting method comprises the steps that (1) high-temperature-resistant material powder is laid at the bottom in a high-temperature-resistant box body; and (2) the bottom of a workblank obtained through 3D printing is embedded into the high-temperature-resistant material powder, so that the workblank is supported by the high-temperature-resistant material powder, and gaps generated by shrinkage deformation of the workblank are filled with the high-temperature-resistant material powder during sintering. According to the supporting method and the supporting device for 3D printing sintering, the supporting effect on the workblank is good, the workblank is not prone to deformation in the sintering process and can be easily taken out of the supporting structure, the cost is reduced, and the 3D printing range is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a supporting method and a supporting device for 3D printing sintering. Background Art

[0002] Binder jetting 3D printing technology is a 3D additive manufacturing technology based on a powder bed. Unlike traditional laser sintering technology, binder jetting technology uses an inkjet print head to spray a binder onto a powder material, thereby bonding powder layers in selected areas. These powder layers are combined together through the penetration of the binder, stacked layer by layer, and finally form a three-dimensional structured product. Binder jetting technology is suitable for a variety of materials, including polymer materials, metals, and ceramics. When used for metal and ceramic materials, the printed product originals need to be treated at high temperature to first remove the binder between the powder particles, and then achieve metallurgical bonding between the powder particles to obtain a finished product with a certain density and strength.

[0003] In the patent with publication number CN115255382A, a 3D printing conformal sintering support method and device are disclosed, wherein the sintering support method includes: dividing the parts in the forming workbench into a printing area, a support area and an isolation area; the inkjet print head sprays a binder toward the printing area and the support area respectively, and sprays an isolation film toward the isolation area to realize the printing of the blank and the support structure. By setting a support structure printed together with the blank, the shape of the blank and the support structure are adapted, so that in the subsequent sintering process, it is convenient to play a good supporting role for the blank and prevent the blank from deformation.

[0004] However, the above method has the following problems: 1. The support and the blank are made of the same material. The support is sintered together with the blank. When the blank shrinks and deforms, the support will also shrink and deform. When the shrinkage deformation of the support is greater than the shrinkage deformation of the blank, it will exert force on the blank, which may cause the blank to deform. 2. For small products with complex shapes, after sintering, due to the shrinkage deformation of the support, the blank is easily stuck by the support and difficult to remove, resulting in product scrapping. 3. When the blank is a special-shaped or asymmetrical shape, the shrinkage deformation at the bottom of the blank is inconsistent during sintering, which will cause the side of the blank with a larger shrinkage deformation to be suspended, and then the blank will tilt to this side, which will affect the molding quality of the blank. 4. The weight of the support structure of some products is even greater than the weight of the product, which makes the cost of the support structure greater than the cost of the product. The cost is too high and not suitable for 3D printing, resulting in the limitation of the scope of 3D printing. Summary of the invention

[0005] The present invention provides a support method and a support device for 3D printing sintering, aiming to solve the technical problems in the prior art that a blank is easy to deform and difficult to be removed from a support structure.

[0006] The 3D printing sintering support method of the present invention comprises the following steps:

[0007] (1) Laying high temperature resistant material powder on the bottom of the high temperature resistant box;

[0008] (2) at least the bottom portion of the 3D printed blank is buried in the high temperature resistant material powder, so that the high temperature resistant material powder supports the blank and fills the gaps in the blank caused by shrinkage deformation during sintering.

[0009] In the present invention, the powdered high-temperature resistant material can be applied to blanks of different shapes and sizes, and has a good supporting effect on the blanks; the high-temperature resistant material powder will not shrink or deform during the sintering process, and thus will not exert additional force on the blanks to prevent deformation of the blanks; the high-temperature resistant material powder can fill the gaps caused by shrinkage and deformation of the blanks, so that the high-temperature resistant material powder always supports the blanks to prevent the blanks from moving or tilting, etc., thereby improving the molding quality of the blanks, and is particularly suitable for special-shaped or asymmetric blanks; after sintering is completed, the powdered high-temperature resistant material is easier to clean, and the blanks will not be stuck by the support structure and difficult to remove; since there is no need to design and print the support structure in the printing stage, printing time, support structure consumption, and support structure design and research and development investment are saved, and the cost reduction also expands the scope of 3D printing, and saves powder cleaning time and the time for applying anti-sintering material particles between the blanks and the support structure, thereby improving production efficiency.

[0010] Preferably, step (3) is further included between step (1) and step (2): vacuum adsorption and / or vibration of the high temperature resistant material powder in the high temperature resistant box body to make the high temperature resistant material powder dense;

[0011] After step (2), the method further includes step (4): vacuum adsorbing and / or vibrating the high temperature resistant material powder again to make the high temperature resistant material powder fit the blank.

[0012] Through vacuum adsorption and vibration, the high-temperature resistant material powder is made denser, fits better with the blank, and has a better supporting effect.

[0013] Preferably, after step (4), the method further comprises:

[0014] (5) placing the high temperature resistant box body into a sintering furnace and sintering according to a set process;

[0015] (6) After sintering is completed, a finished product is formed and taken out;

[0016] (7) Pour out the high temperature resistant material powder in the high temperature resistant box body, and set it aside after vibration screening.

[0017] By screening and recovering high temperature resistant material powder, the cost can be greatly reduced and the economic benefit can be improved.

[0018] Preferably, in step (5), the setting process includes the following steps implemented in sequence: debinding, sintering and cooling.

[0019] Through the degreasing, sintering and cooling steps, the degreasing and sintering of the blank are achieved, and the sintered finished product has the advantages of densification, reduced porosity, and no stress concentration.

[0020] Preferably, step (2) comprises:

[0021] (21) determining the number of the blanks to be accommodated in the high temperature resistant box body according to the cross-sectional dimensions of the high temperature resistant box body and the dimensions of the blanks;

[0022] (22) The blank is placed in the high temperature resistant material powder in the high temperature resistant box, and two adjacent blanks are placed at intervals.

[0023] By arranging multiple blanks in the high-temperature resistant box body, the space utilization rate of the high-temperature resistant box body and the production efficiency of the product are improved, and the intervals between two adjacent blanks can prevent the two adjacent blanks from sticking together during the sintering process, or from affecting each other due to shrinkage and deformation during the sintering process, thereby affecting the molding quality of the blanks.

[0024] Preferably, in step (2), the bottom of the blank is spaced apart from the bottom wall of the high temperature resistant box body; and the top of the blank exceeds the top surface of the high temperature resistant material powder.

[0025] This arrangement can prevent the blank from contacting the bottom of the high temperature resistant box body during the sintering process, and reduce the pressure of the high temperature resistant material powder on the top of the blank, so that the molding quality of the blank is better.

[0026] Preferably, in step (1), the thickness of the laid high temperature resistant material powder is 1 mm to 30 mm; the high temperature resistant material powder is a spherical powder, and the diameter of the high temperature resistant material powder is 1 nm to 200 μm; the material of the high temperature resistant material powder and the high temperature resistant box body are both one of graphite, diamond, AlN, BeO, Si3N4, SiC, Al2O3 or ZrO2.

[0027] The present invention also provides a support device for 3D printing sintering, comprising a high temperature resistant box body, high temperature resistant material powder laid in the high temperature resistant box body, a vibration mechanism for vibrating the high temperature resistant material powder and / or a vacuum adsorption mechanism for vacuum adsorbing the high temperature resistant material powder.

[0028] Preferably, an opening is provided on the top of the high temperature resistant box body, and a plurality of air intake holes connecting the inside and the outside of the high temperature resistant box body are evenly distributed on the bottom wall of the high temperature resistant box body, and the size of the air intake holes is not larger than the diameter of the high temperature resistant material powder; the air intake holes are circular, diamond-shaped, rectangular or triangular.

[0029] Preferably, the high temperature resistant box body is placed above the vibration mechanism and the vacuum adsorption mechanism; the vibration mechanism is an ultrasonic oscillator or a vibrating screen; the vacuum adsorption mechanism includes a suction cup and a vacuum generator connected to the suction cup.

[0030] The beneficial effects are:

[0031] 1. In the present invention, the powdered high-temperature resistant material can be applied to blanks of different shapes and sizes, and has a good supporting effect on the blanks; the powdered high-temperature resistant material will not shrink or deform during the sintering process, and thus will not exert additional force on the blanks to prevent deformation of the blanks; the powdered high-temperature resistant material can fill the gaps caused by the shrinkage and deformation of the blanks, so that the powdered high-temperature resistant material always supports the blanks to prevent the blanks from moving or tilting, etc., so that the molding quality of the blanks is better, and the blanks are particularly suitable for special-shaped or asymmetric blanks; after sintering, the powdered high-temperature resistant material is easier to clean, and the blanks will not be stuck by the support structure and difficult to remove; since there is no need to design and print the support structure in the printing stage, the printing time, the consumption of the support structure, and the investment in the design and research and development of the support structure are saved, the cost reduction also expands the scope of 3D printing, and saves the time for cleaning powder and the time for applying anti-sintering material particles between the blanks and the support structure, thereby improving production efficiency.

[0032] 2. Through vacuum adsorption and vibration, the high temperature resistant material powder is made denser, fits better with the blank, and has better supporting effect.

[0033] 3. Recovering high temperature resistant material powder by screening can greatly reduce costs and improve economic benefits.

[0034] 4. Through the degreasing, sintering and cooling steps, the degreasing and sintering of the blank are achieved, and the sintered finished product has the advantages of densification, reduced porosity, and no stress concentration.

[0035] 5. By arranging multiple blanks in the high temperature resistant box body, the space utilization rate of the high temperature resistant box body and the production efficiency of the product are improved, and the interval between two adjacent blanks can prevent the two adjacent blanks from sticking together during the sintering process, or affecting each other due to shrinkage deformation during the sintering process, thereby affecting the molding quality of the blanks.

[0036] 6. By spacing the bottom of the blank and the bottom wall of the high-temperature resistant box body, the top of the blank exceeds the top surface of the high-temperature resistant material powder, which can prevent the blank from contacting the bottom of the high-temperature resistant box body during sintering, and reduce the pressure of the high-temperature resistant material powder on the top of the blank, so that the molding quality of the blank is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0038] Figure 1 This is a flow chart of a 3D printing sintering support method according to an embodiment of the present invention;

[0039] Figure 2 for Figure 1 Flow chart of step S3;

[0040] Figure 3 A three-dimensional diagram of a support device for 3D printing sintering according to an embodiment of the present invention;

[0041] Figure 4 A three-dimensional diagram of a bracket, a vibration mechanism and a vacuum adsorption mechanism according to an embodiment of the present invention;

[0042] Figure 5 A three-dimensional diagram of a high temperature resistant box body according to an embodiment of the present invention;

[0043] Figure 6 It is a vertical cross-sectional view of a solid blank placed in a high temperature resistant box body according to an embodiment of the present invention;

[0044] Figure 7 This is a vertical cross-sectional view of a hollow blank placed in a high temperature resistant box body according to an embodiment of the present invention.

[0045] Description of reference numerals:

[0046] 1. High temperature resistant box body; 11. Air suction hole; 2. Vibration mechanism; 3. Suction cup; 4. High temperature resistant material powder; 5. Bracket; 6. Blank. DETAILED DESCRIPTION

[0047] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0048] like Figures 1 to 7 As shown, the present invention provides a 3D printing sintering support method, comprising the following steps:

[0049] S1, laying high temperature resistant material powder 4 on the bottom of the high temperature resistant box body 1;

[0050] S2, vacuum adsorption and / or vibration of the high temperature resistant material powder 4 in the high temperature resistant box body 1 to make the high temperature resistant material powder 4 dense;

[0051] S3, burying at least the bottom portion of the 3D printed blank 6 in high temperature resistant material powder, so that the high temperature resistant material powder supports the blank 6, and the high temperature resistant material powder fills the gap caused by the shrinkage deformation of the blank 6 during sintering;

[0052] S4, vacuum adsorbing and / or vibrating the high temperature resistant material powder 4 again to make the high temperature resistant material powder 4 fit the blank 6.

[0053] In step S1, the material of the high temperature resistant material powder 4 is one of graphite, diamond, AlN, BeO, Si3N4, SiC, Al2O3 or ZrO2. The above materials all have high melting points and are often used as high temperature resistant materials. Their melting temperatures far exceed the sintering temperature of 1000 to 1500°C, and the chemical properties of the above materials are relatively stable. Therefore, the above materials will not melt during the sintering process, nor will they undergo physical or chemical reactions themselves, nor will they undergo chemical reactions with the blank 6, so they can meet the sintering requirements. For example, the melting point of graphite is 3652°C to 3697°C, the melting point of diamond is 3550°C, the melting point of Al2O3 is 2054°C, and the melting point of ZrO2 is 2700°C, all of which far exceed the sintering temperature. The thermal conductivity of graphite is 700-1300W / (m·K), and the thermal conductivity of diamond is 1000-2600W / (m·K). Both graphite and diamond have excellent thermal conductivity and can meet the purpose of thermal conductivity of the blank 6 during the sintering process. Therefore, the high temperature resistant material powder 4 is preferably graphite and diamond. Of course, the high temperature resistant material powder 4 can also be other materials, as long as it has a higher melting point and better thermal conductivity, it is within the protection scope of the present invention, and is not listed one by one in this embodiment.

[0054] In order to meet the requirements of the high temperature resistant box body 1 during the sintering process, the high temperature resistant box body 1 should have the characteristics of high temperature resistance, good thermal conductivity, and not easy to deform. Therefore, the high temperature resistant box body 1 can be one of graphite, diamond, AlN, BeO, Si3N4, SiC, Al2O3 or ZrO2. In this embodiment, the material of the high temperature resistant box body 1 is preferably graphite and diamond. Both graphite and diamond have good high temperature resistance and thermal conductivity, and are hard and not easy to deform, which can meet the use requirements. Of course, the high temperature resistant box body 1 can also be made of other materials, as long as it meets the characteristics of high temperature resistance, good thermal conductivity, and not easy to deform, it is within the protection scope of the present invention, and is not listed one by one in this embodiment.

[0055] The thickness of the high temperature resistant material powder 4 is 1 mm to 30 mm. In the present invention, the thickness of the high temperature resistant material powder 4 can be determined according to the size, shape and quality of the blank 6. For example, for a blank 6 with a larger size, a more complex shape and a heavier weight, the thickness of the high temperature resistant material powder 4 can be appropriately thicker. For a blank 6 with a smaller size, a simpler shape and a lighter weight, the thickness of the high temperature resistant material powder 4 can be appropriately thinner. This setting can not only meet the use requirements, but also save the use of the high temperature resistant material powder 4 and avoid waste.

[0056] The high temperature resistant material powder 4 is a spherical powder, and the diameter of the high temperature resistant material powder 4 is 1nm to 200μm. The size of the high temperature resistant material powder 4 is roughly the same as the size range of the metal powder used to print the blank 6. This arrangement not only ensures that the high temperature resistant material powder 4 has good fluidity, but also makes the high temperature resistant material powder 4 fit more closely with the blank 6, thereby providing better support for the blank 6.

[0057] In step S2, the high temperature resistant material powder 4 directly laid in the high temperature resistant box body 1 will be relatively loose. Through vacuum adsorption and vibration, the high temperature resistant material powder 4 can be made more compact, and the high temperature resistant material powder 4 can be prevented from flowing during the movement or sintering of the high temperature resistant box body 1, causing the blank 6 to move or tilt, thereby affecting the sintering effect of the blank 6. Vacuum adsorption can be achieved by a vacuum adsorption mechanism, and vibration can be achieved by a vibration mechanism. The bottom of the high temperature resistant box body 1 is provided with a suction hole 11 for vacuum adsorption. Vacuum adsorption and vibration can be performed alternately or simultaneously, so that the compacting effect of the high temperature resistant material powder 4 is better. Of course, only vibration or only vacuum adsorption can be performed, which can be selected according to needs.

[0058] In step S3, since the spherical high temperature resistant material has good fluidity, that is, it has flexibility, when the blank 6 is placed in the high temperature resistant material powder 4, the high temperature resistant material powder 4 can flow according to the shape of the blank 6, so that the high temperature resistant material powder 4 fits the blank 6 and plays a good supporting role for the blank 6. Moreover, during the sintering process, when the blank 6 shrinks and deforms, the high temperature resistant material powder 4 in contact with the blank 6 is in a rolling state, which will not hinder the shrinkage and deformation of the blank 6, so that the molding quality of the blank 6 is better, and the rolling high temperature resistant material powder 4 can also timely fill the gap caused by the shrinkage and deformation of the blank 6, so that the high temperature resistant material powder 4 is always in contact with the blank 6, that is, always supports the blank 6, prevents the blank 6 from moving, tilting, etc., so that the molding quality of the blank 6 is further improved.

[0059] like Figure 1 and Figure 2 As shown, step S3 includes:

[0060] S31, determining the number of blanks 6 to be accommodated in the high temperature resistant box body 1 according to the cross-sectional size of the high temperature resistant box body 1 and the size of the blank 6;

[0061] S32, placing the blank 6 in the high temperature resistant material powder 4 in the high temperature resistant box body 1, and placing two adjacent blanks 6 at intervals.

[0062] In step S31, in order to improve the space utilization rate of the high temperature resistant box body 1 and the production efficiency of the product, multiple blanks 6 are arranged in the high temperature resistant box body 1, and the number of blanks 6 is determined according to the cross-sectional size of the high temperature resistant box body 1 and the size of the blanks 6. The shapes and sizes of the multiple blanks 6 can be the same or different, but they need to be of the same material, so as to achieve the best sintering performance under the same temperature curve during the sintering process, and to avoid the element diffusion of the blanks 6 of different materials causing pollution. When the shapes and sizes of the multiple blanks 6 are the same, they can be arranged at the same height in the high temperature resistant box body 1. When the shapes and sizes of the multiple blanks 6 are different, the multiple blanks 6 can be arranged at different heights in the high temperature resistant box body 1 according to actual conditions. The setting height of the multiple blanks 6 can be set according to actual needs, and is not limited in this embodiment.

[0063] In step S32 , two adjacent blanks 6 are spaced apart to prevent the two adjacent blanks 6 from being bonded together during the sintering process, or from affecting each other due to shrinkage and deformation during the sintering process, thereby affecting the molding quality of the blanks 6 .

[0064] like Figure 6 and Figure 7As shown, in step S3, the bottom of the blank 6 is spaced apart from the bottom wall of the high temperature resistant box body 1. In the present invention, in order to prevent the blank 6 from contacting the bottom of the high temperature resistant box body 1 during the sintering process, thereby affecting the molding quality of the blank 6, the blank 6 and the bottom wall of the high temperature resistant box body 1 are spaced apart. For example, the distance between the blank 6 and the bottom wall of the high temperature resistant box body 1 is 2 mm. Of course, the distance between the blank 6 and the bottom wall of the high temperature resistant box body 1 can be adjusted according to the shape and size of the blank 6.

[0065] The top of the blank 6 exceeds the top surface of the high temperature resistant material powder 4. In the present invention, in order to reduce the pressure of the high temperature resistant material powder 4 on the blank 6 and affect the molding quality of the blank 6, the high temperature resistant material powder 4 may not be provided at the top position of the blank 6, that is, the high temperature resistant material powder 4 is exposed at the top of the blank 6, especially for some hollow or thin-walled blanks 6, which can prevent the blank 6 from being deformed or collapsed by pressure. For example, Figure 7 As shown, for some hollow or thin-walled blanks 6, the internal cavity of the blank 6 is filled with high temperature resistant material powder 4, so that the top wall of the blank 6 is exposed to the high temperature resistant material powder 4. This arrangement can not only provide good support for the blank 6, but also prevent the blank 6 from being pressed. Figure 6 As shown, for some solid blanks 6, the lower 1 / 2 height of the blank 6 can be buried in the high temperature resistant material powder 4, and the upper 1 / 2 height of the blank 6 is exposed to the high temperature resistant material powder 4. This arrangement can not only provide good support for the blank 6, but also prevent the blank 6 from being pressed. For some special-shaped blanks 6, the depth of the blank 6 buried in the high temperature resistant material powder 4 can be set according to actual conditions. Of course, the depth of the blank 6 buried can be determined according to the shape and material of the blank 6 to ensure that the blank 6 is not squeezed and has a good support effect.

[0066] In step S4, after the blank 6 is placed in the high temperature resistant material powder 4, the high temperature resistant material powder 4 is vacuum adsorbed and vibrated again, which makes the high temperature resistant material powder 4 more compact on the one hand, and makes the high temperature resistant material powder 4 fit more closely with the blank 6 on the other hand, thereby providing better support for the blank 6. In this step, vacuum adsorption and vibration can be performed alternately or simultaneously, or only vibration or only vacuum adsorption can be performed, which can be selected according to needs to meet different usage requirements.

[0067] In the present invention, the high temperature resistant material powder 4 is first laid in the high temperature resistant box body 1, and then the high temperature resistant material powder 4 is made dense after vacuum adsorption and / or vibration, and then at least the bottom part of the printed blank 6 is buried in the high temperature resistant material powder 4, so that the high temperature resistant material powder 4 supports the blank 6, and finally the blank 6 and the high temperature resistant material powder 4 are vacuum adsorbed and / or vibrated to make the blank 6 and the high temperature resistant material powder 4 fit more closely.

[0068] Compared with the prior art, the present invention has the following advantages: First, since the powdered high-temperature resistant material has fluidity, that is, it has a certain flexibility, it can be applied to blanks 6 of different shapes and sizes, and play a good supporting role for the blanks 6; Second, in the subsequent sintering process, since the high-temperature resistant material powder 4 has high-temperature resistance and flexibility, it will not shrink and deform, so no additional force will be applied to the blank 6 to prevent the blank 6 from deforming; Third, after the blank 6 shrinks and deforms, the high-temperature resistant material powder 4 can fill the gap caused by the shrinkage deformation in time, so that the high-temperature resistant material powder 4 is always in contact with the blank 6, that is, it always supports the blank 6, thereby avoiding the blank 6 from shrinking. The blank 6 moves or tilts, so that the molding quality of the blank 6 is better, especially suitable for special-shaped or asymmetrical blanks 6; Fourth, for some small blanks 6 with complex shapes, after sintering, the powdered high-temperature resistant material is easier to clean, and the blank 6 will not be stuck by the support structure and difficult to remove; Fifth, since there is no need to design and print the support structure in the printing stage of the blank 6, the printing time, the consumption of the support structure, and the investment in the design and research and development of the support structure are saved, the cost reduction also expands the scope of 3D printing, and saves the time of cleaning powder and the time of applying anti-sintering material particles between the blank 6 and the support structure, thereby improving production efficiency. For example, the anti-sintering material particles are ceramic particles.

[0069] like Figure 1 As shown, after step S4, it also includes:

[0070] S5, placing the high temperature resistant box body 1 into a sintering furnace and sintering according to a set process;

[0071] S6. After sintering is completed, a finished product is formed and taken out;

[0072] S7, pour out the high temperature resistant material powder 4 in the high temperature resistant box body 1, and set it aside after vibration screening.

[0073] In step S5, the high temperature resistant box body 1 is taken out from the corresponding vacuum adsorption mechanism and vibration mechanism after vacuum adsorption and vibration, and then put into the sintering furnace for sintering. Taking the sintering process of the medical orthopedic tool mortar as an example, the orthopedic tool mortar is printed with 17-4PH stainless steel powder, wherein 17-4PH stainless steel is a precipitation hardening martensitic stainless steel, which contains copper and niobium elements and has high strength, high hardness and good corrosion resistance. The chemical composition of this stainless steel includes iron, chromium, nickel, copper, silicon, niobium, manganese and carbon.

[0074] The mass fractions of various elements are shown in Table 1. The particle size of 17-4PH stainless steel powder is 0 to 33 μm, and the tap density is 4.76 g / cm 3 , the powder particle size distribution is D10: 4.91μm, D50: 14.99μm, D90: 28.36μm.

[0075] Table 1

[0076]

[0077] The setting process includes the following steps implemented in sequence: degreasing, sintering and cooling. Degreasing may include negative pressure degreasing and vacuum degreasing. Sintering includes vacuum sintering and partial pressure sintering. Cooling includes rapid cooling and natural cooling. The above steps can be adjusted and combined according to actual production needs to obtain the best sintering effect. The orthopedic tool mortar sintering process in this embodiment adopts the following steps implemented in sequence: negative pressure degreasing, vacuum sintering, partial pressure sintering and rapid cooling, as shown in Table 2.

[0078] Table 2

[0079]

[0080]

[0081] In Table 2, the temperature and time corresponding to each step refer to the time required for the temperature of the previous step to change to the temperature corresponding to the step. As shown in Step 2 and Step 3, the time required to increase the temperature from 150°C in Step 2 to 300°C in Step 3 is 75 minutes. In particular, the time required to increase the temperature from room temperature to 50°C in Step 1 is 30 minutes. The temperature in Step 4 is the same as that in Step 3, both of which are 300°C, indicating that Step 4 is kept at 300°C for 90 minutes.

[0082] The above-mentioned negative pressure debinding is a process that implements negative pressure debinding technology in a sintering furnace. This process can effectively remove binders and other organic matter from the blank 6 while sintering to obtain the final densified product. When heated in a vacuum environment, the binder and other organic matter begin to decompose and evaporate. Since the vacuum environment reduces the boiling point of the binder and other organic matter, debinding can be performed at a relatively low temperature.

[0083] Vacuum sintering is a process for sintering the blank 6 in a vacuum environment, which can sinter the blank 6 at a lower temperature, reduce or eliminate oxidation and other chemical reactions, and thus produce a product with high quality and high performance. As shown in steps 10 to 11 in Table 2, heating is gradual to ensure uniform temperature distribution and prevent deformation or damage of the blank 6. As shown in steps 10 and 12 in Table 2, during the heating process, heat preservation operation is performed to promote densification of the blank 6, reduce porosity, and eliminate stress concentration.

[0084] Partial pressure sintering is a special sintering technology, which affects the molding quality of the sintered blank 6 by controlling the atmosphere composition and pressure in the sintering furnace during the sintering process. Specifically, during the partial pressure sintering process, the atmosphere in the furnace is composed of one or more gases. By adjusting the total pressure in the sintering furnace and the partial pressure of each component gas, the chemical reaction, grain growth, densification, etc. of the material during the sintering process can be affected. Partial pressure sintering can reduce the oxidation of the blank 6, promote densification, improve the microstructure, and improve the performance. As shown in Table 2, the gas used is argon, and of course it can also be nitrogen or other inert gases.

[0085] Rapid cooling refers to the process of rapidly cooling the blank 6 from a high temperature state to room temperature or a certain temperature after the sintering process is completed. Through rapid cooling, the microstructure of the blank 6 can be maintained, grain growth can be suppressed, segregation can be reduced, and production efficiency can be improved. As shown in step 16 in Table 2, in this embodiment, cooling is performed by gas. Of course, in order to reduce the cooling time and improve the cooling efficiency, oil cooling, water cooling, liquid nitrogen cooling, etc. can also be used.

[0086] In step S7, after sintering, the physical and chemical properties of the high temperature resistant material powder 4 remain unchanged, so it can be reused after vibration screening. Compared with the prior art in which the support structure is disposable, it can greatly reduce costs and improve economic benefits.

[0087] like Figure 1 As shown, the overall working process of the 3D printing sintering support method of the present invention is as follows:

[0088] S1, laying high temperature resistant material powder 4 on the bottom of the high temperature resistant box body 1;

[0089] S2, vacuum adsorption and / or vibration of the high temperature resistant material powder 4 in the high temperature resistant box body 1 to make the high temperature resistant material powder 4 dense;

[0090] S3, burying at least the bottom portion of the 3D printed blank 6 in the high temperature resistant material powder 4, so that the high temperature resistant material powder 4 supports the blank 6, and the high temperature resistant material powder 4 fills the gap caused by the shrinkage deformation of the blank 6 during sintering;

[0091] S4, vacuum adsorbing and / or vibrating the high temperature resistant material powder 4 again, so that the high temperature resistant material powder 4 fits the blank 6;

[0092] S5, placing the high temperature resistant box body 1 into a sintering furnace and sintering according to a set process;

[0093] S6. After sintering is completed, a finished product is formed and taken out;

[0094] S7, pour out the high temperature resistant material powder 4 in the high temperature resistant box body 1, and set it aside after vibration screening.

[0095] like Figures 3 to 7 As shown, the present invention also provides a support device for 3D printing sintering, including a high temperature resistant box body 1, high temperature resistant material powder 4 laid in the high temperature resistant box body 1, a vibration mechanism 2 for vibrating the high temperature resistant material powder 4 and / or a vacuum adsorption mechanism for vacuum adsorption of the high temperature resistant material powder 4.

[0096] In the present invention, the high temperature resistant material powder 4 is first laid in the high temperature resistant box body 1, and then the vibration mechanism 2 and the vacuum adsorption mechanism are used for vibration and vacuum adsorption to make the high temperature resistant material powder 4 dense, and then the blank 6 is placed in the high temperature resistant material powder 4, so that the high temperature resistant material powder 4 supports the blank 6, and finally the vibration mechanism 2 and the vacuum adsorption mechanism are started again, so that the high temperature resistant material powder 4 and the blank 6 fit more closely and have a better supporting effect. During sintering, the high temperature resistant box body 1 is taken out from the vibration mechanism 2 and the vacuum adsorption mechanism, placed in a sintering furnace, and sintered according to the set process.

[0097] The support device for 3D printing sintering of the present invention can be suitable for blanks 6 of different shapes and sizes, and will not apply deformation force to the blank 6 during the sintering process, which can prevent the blank 6 from deformation, so that the molding quality of the blank 6 is better. After sintering is completed, the powdered high-temperature resistant material is easier to clean, and the blank 6 will not be stuck by the support structure and difficult to remove. The high-temperature resistant material powder 4 can be reused after vibration screening, thereby reducing costs and improving economic benefits.

[0098] like Figures 3 to 7As shown, the top of the high temperature resistant box body 1 is provided with an opening, and the bottom wall of the high temperature resistant box body 1 is evenly distributed with a plurality of air suction holes 11 connecting the inside and outside of the high temperature resistant box body 1, and the size of the air suction holes 11 is not larger than the diameter of the high temperature resistant material powder 4. In the present invention, the plurality of air suction holes 11 provided on the bottom wall of the high temperature resistant box body 1 are used for air suction by the vacuum adsorption mechanism, thereby making the high temperature resistant material powder 4 in the high temperature resistant box body 1 dense. And the size of the air suction holes 11 is less than or equal to the diameter of the high temperature resistant material powder 4, so that during the vacuum adsorption process, the high temperature resistant material powder 4 will not pass through the air suction holes 11 to reach the outside of the high temperature resistant box body 1.

[0099] like Figures 5 to 7 As shown, the suction hole 11 is circular. The circular suction hole 11 is conducive to the flow of airflow, so that the vacuum adsorption effect is better. Of course, the suction hole 11 can also be diamond, rectangular or triangular, etc., which can be selected according to needs.

[0100] like Figure 3 and Figure 4 As shown, the high temperature resistant box body 1 is placed above the vibration mechanism 2 and the vacuum adsorption mechanism. The vibration mechanism 2 and the vacuum adsorption mechanism are both arranged at the bottom of the bracket 5, and the high temperature resistant box body 1 is arranged at the top of the bracket 5. The vibration mechanism 2 is an ultrasonic oscillator. The ultrasonic oscillator can generate high-frequency vibrations, which can vibrate the high temperature resistant material powder 4, reduce the gap between the high temperature resistant material powders 4, and make the high temperature resistant material powder 4 more compact. And the ultrasonic oscillator can achieve the purpose of compacting the high temperature resistant material powder 4 without contacting the high temperature resistant box body 1, so that the setting position of the vibration mechanism 2 is more flexible. Of course, the vibration mechanism 2 can also adopt a contact type, for example, other devices that can generate vibrations such as a vibrating screen can be used.

[0101] like Figure 3 and Figure 4 As shown, the vacuum adsorption mechanism includes a suction cup 3 and a vacuum generator connected to the suction cup 3. The vacuum generator can be a vacuum pump. The suction cup 3 is located below the high temperature resistant box body 1, and the opening faces upward. Under the action of the vacuum pump, negative pressure is generated in the suction cup 3, which can adsorb the high temperature resistant material powder 4 in the high temperature resistant box body 1, making the high temperature resistant material powder 4 more dense. There can be multiple suction cups 3, and they are evenly distributed at the bottom of the high temperature resistant box body 1, such as Figure 3 and Figure 4 Of course, a large-sized suction cup 3 can also be used, and the suction cup 3 matches the size of the bottom of the high-temperature resistant box body 1 and can be set as needed.

[0102] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "upper", "lower", "horizontal", "top", "bottom", "inside", "outside" and the like, which indicate the orientation or position relationship, are based on the orientation or position relationship shown in the drawings of this specification, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element involved must have the specific orientation, be constructed and operate in a specific orientation. Therefore, the above-mentioned orientation or position relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0103] In addition, in the description of this specification, “plurality” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A support method for 3D printing sintering, characterized in that: The following steps are involved: (1) Laying high temperature resistant material powder on the bottom of the high temperature resistant box; (2) at least the bottom portion of the 3D printed blank is buried in the high temperature resistant material powder, so that the high temperature resistant material powder supports the blank and fills the gaps in the blank caused by shrinkage deformation during sintering.

2. The 3D printing sintering support method according to claim 1, characterized in that: The method further includes step (3) between step (1) and step (2): vacuum adsorbing and / or vibrating the high temperature resistant material powder in the high temperature resistant box body to make the high temperature resistant material powder dense; After step (2), the method further includes step (4): vacuum adsorbing and / or vibrating the high temperature resistant material powder again to make the high temperature resistant material powder fit the blank.

3. The 3D printing sintering support method according to claim 2, characterized in that: After step (4), the method further includes: (5) placing the high temperature resistant box body into a sintering furnace and sintering according to a set process; (6) After sintering is completed, a finished product is formed and taken out; (7) Pour out the high temperature resistant material powder in the high temperature resistant box body, and set it aside after vibration screening.

4. The 3D printing sintering support method according to claim 3, characterized in that: In step (5), the setting process includes the following steps implemented in sequence: degreasing, sintering and cooling.

5. The 3D printing sintering support method according to claim 1, characterized in that: Step (2) comprises: (21) determining the number of the blanks to be accommodated in the high temperature resistant box body according to the cross-sectional dimensions of the high temperature resistant box body and the dimensions of the blanks; (22) The blank is placed in the high temperature resistant material powder in the high temperature resistant box, and two adjacent blanks are placed at intervals.

6. The 3D printing sintering support method according to claim 1, characterized in that: In step (2), the bottom of the blank is spaced apart from the bottom wall of the high temperature resistant box body; The top of the blank exceeds the top surface of the high temperature resistant material powder.

7. The 3D printing sintering support method according to claim 1, characterized in that: In step (1), the thickness of the high temperature resistant material powder laid is 1 mm to 30 mm; The high temperature resistant material powder is a spherical powder, and the diameter of the high temperature resistant material powder is 1nm to 200μm; The materials of the high temperature resistant material powder and the high temperature resistant box body are one of graphite, diamond, AlN, BeO, Si3N4, SiC, Al2O3 or ZrO2.

8. A support device for 3D printing sintering, characterized in that: It includes a high temperature resistant box body, high temperature resistant material powder laid in the high temperature resistant box body, a vibration mechanism for vibrating the high temperature resistant material powder and / or a vacuum adsorption mechanism for vacuum adsorbing the high temperature resistant material powder.

9. The 3D printing sintering support device according to claim 8, characterized in that: An opening is provided on the top of the high temperature resistant box body, and a plurality of air intake holes connecting the inside and the outside of the high temperature resistant box body are evenly distributed on the bottom wall of the high temperature resistant box body, and the size of the air intake holes is not larger than the diameter of the high temperature resistant material powder; the air intake holes are circular, diamond-shaped, rectangular or triangular.

10. The 3D printing sintering support device according to claim 8, characterized in that: The high temperature resistant box body is placed above the vibration mechanism and the vacuum adsorption mechanism; The vibration mechanism is an ultrasonic oscillator or a vibrating screen; The vacuum adsorption mechanism includes a suction cup and a vacuum generator connected to the suction cup.

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