A method and apparatus for isostatic pressing heat treatment of 3D printed peek material

Abstract

This invention discloses a method and apparatus for isostatic pressing heat treatment of 3D printed PEEK materials. The method comprises: (1) surface cleaning, static electricity removal, and drying of the printed PEEK material; (2) using ceramic sand as a heat-conducting and pressure-transferring medium, first spreading the ceramic sand in the isostatic pressing device, then placing the 3D printed PEEK material in the device, continuing to fill with ceramic sand until completely covered, and performing hydraulic and heat treatment on the device; the device includes a metal container, a hydraulic device, and a worktable. The metal container includes a box body, a top cover plate, a movable base plate, felt, a fixed base plate, and a manual screw. The fixed base plate has a large hole in the middle, and the hydraulic rod of the hydraulic device adjusts the position of the movable base plate through the large hole; the worktable is used to support the metal container and the hydraulic device. The isostatic pressing heat treatment method and apparatus used in this invention can significantly improve the crystallinity, density, and mechanical properties of 3D printed PEEK materials.

Description

Technical Field

[0001] This invention relates to the field of 3D printing materials technology, and specifically to a method and apparatus for isostatic pressing heat treatment of PEEK materials for 3D printing. Background Technology

[0002] With the development of industrial technology, digitalization and intelligentization will become its development trend. Among them, 3D printing technology, as an additive manufacturing method, has received widespread attention. With the gradual development of 3D printing technology, it has begun to be used in more and more industries. The entire process is one-time molding, with high material utilization, eliminating the mold development stage, and is particularly suitable for the customized production of irregular curved parts, saving a lot of labor and costs.

[0003] There are two main 3D printing technologies for PEEK materials: fused deposition modeling (FDM) and selective laser sintering (SLS). FDM involves melting PEEK filaments and extruding them through a nozzle to form the final product. SLS uses a laser to melt PEEK powder. While FDM is more widely used due to its lower cost, its process characteristics result in lower crystallinity of the PEEK material, leading to lower mechanical properties compared to injection-molded PEEK. The presence of voids in the PEEK material also contributes to its poorer mechanical properties.

[0004] Existing heat treatment methods for PEEK materials in fused deposition modeling (FDM) 3D printing only improve the crystallinity of the printed parts to enhance their mechanical properties, but cannot effectively eliminate the pores inside the printed parts. Furthermore, because there is no equal pressure restriction during the heat treatment process, PEEK materials are prone to thermal deformation, leading to dimensional errors in the samples. Summary of the Invention

[0005] Purpose of the invention: In order to solve the technical problems existing in the prior art, the present invention aims to provide an isostatic pressing heat treatment method suitable for 3D printing PEEK materials that can improve the crystallinity, density and mechanical properties of materials. Furthermore, the present invention also provides an apparatus suitable for isostatic pressing heat treatment of 3D printing PEEK materials.

[0006] Technical solution: The isostatic pressing heat treatment method for 3D printing PEEK materials described in this invention includes the following steps:

[0007] (1) PEEK material for fused deposition 3D printing is subjected to surface cleaning, static removal and drying treatment;

[0008] (2) Using ceramic sand as a heat conduction and pressure transmission medium, first spread the ceramic sand in the isostatic pressing device, then place the dried fused deposition 3D printing PEEK material in the isostatic pressing device, continue to fill the ceramic sand until it is completely covered, perform hydraulic treatment on the isostatic pressing device, and perform heat treatment after the pressure stabilizes.

[0009] Further, step (1) specifically involves: placing the fused deposition 3D printed PEEK material in an ultrasonic cleaner to clean its surface, using anhydrous ethanol as the cleaning solvent and cleaning time of 10-60 minutes; removing the cleaned 3D printed PEEK material and using an ion gun to dry the surface with anhydrous ethanol, the purpose of which is to remove static electricity from the surface of the PEEK sample and prevent dust from the air from adhering to the sample surface; and placing the dried PEEK material in a forced-air drying oven to dry it thoroughly, with a drying temperature of 70-90°C and a drying time of 30-120 minutes.

[0010] Furthermore, the ceramic sand has a particle size of 20-100μm, preferably 100-150μm, and the ceramic sand is spherical in shape.

[0011] Furthermore, the ceramic sand comprises the following raw materials in parts by weight: 90-95 parts zirconium oxide and 5-10 parts silicon dioxide, which have the advantages of high temperature resistance and non-biological toxicity, and will not cause pollution to the material surface.

[0012] Further, the ceramic sand is characterized in that the depth of the leveling is 10-100mm, preferably 10-40mm, more preferably 20mm, and the depth of complete coverage is 10-100nm, preferably 10-40nm, more preferably 20mm.

[0013] Furthermore, the hydraulic treatment pressure is 1-50 bar, preferably 5-20 bar.

[0014] Furthermore, the heat treatment conditions are: temperature of 160-320℃ and time of 30-300min, preferably, temperature of 250-300℃ and time of 60-180min.

[0015] This invention relates to an isostatic pressing device for 3D printing PEEK materials, comprising a metal container, a hydraulic device, and a worktable. The metal container includes a housing, an upper cover plate located at the upper port of the housing, a movable base plate located inside the housing, a sealing felt layer between the movable base plates, and a fixed base plate and a manual screw located at the lower port of the housing. The fixed base plate has small holes at its four corners for connecting and fixing with the manual screw, and a large hole in the middle of the fixed base plate for docking with the hydraulic device. The hydraulic rod of the hydraulic device adjusts the position of the movable base plate through the large hole, thereby regulating the internal pressure of the metal housing in real time. The worktable supports the metal container and the hydraulic device.

[0016] Furthermore, the metal container also includes an extended housing, which is connected to the housing via a fixing plate and a insert.

[0017] Furthermore, the workbench is equipped with a movable baffle to restrict the movement of the hydraulic device and the housing.

[0018] Furthermore, the hydraulic rod is equipped with a pressure display gauge for real-time monitoring of the pressure inside the metal housing.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention adopts a combination of isostatic pressing and heat treatment to improve the crystallinity, density and mechanical properties of 3D printed PEEK materials. The use of ceramic sand as a heat conduction medium and pressure transmission medium can ensure uniform heating and pressure of the material. While preventing material deformation and damage, it can more efficiently improve the comprehensive performance of the material. Attached Figure Description

[0020] Figure 1 This is a left view of the metal container of the isostatic pressing device for 3D printing PEEK materials according to the present invention;

[0021] Figure 2 This is an exploded view of the metal container of the isostatic pressing device for 3D printing PEEK material according to the present invention;

[0022] Figure 3 This is a front view of the metal container of the isostatic pressing device for 3D printing PEEK materials according to the present invention;

[0023] Figure 4 This is a structural view of the extended box body of the metal container of the isostatic pressing device for 3D printing PEEK materials according to the present invention;

[0024] In the diagram: 1001, top cover plate; 1002, housing; 1003, movable base plate; 1004, felt; 1005, fixed base plate; 1006, manual screw; 1007, hydraulic device; 1008, workbench; 1009, extended housing; 1010, fixed plate; 1011, pin; 1012, movable baffle. Detailed Implementation

[0025] The present invention will now be further described in conjunction with specific embodiments and accompanying drawings.

[0026] like Figures 1-3 As shown, the isostatic pressing device of the present invention for 3D printing PEEK materials includes a metal container, a hydraulic device 1007, and a worktable 1008.

[0027] The metal container includes a housing 1002, an upper cover plate 1001 located at the upper port of the housing, a movable base plate 1003 located inside the housing, a felt 1004 located between the movable base plates 1003, and a fixed base plate 1005 and a manual screw 1006 located at the lower port of the housing. The fixed base plate has small holes at its four corners for connecting and fixing with the manual screw 1006. The fixed base plate 1005 has a large hole in the middle for docking with a hydraulic device 1007. The hydraulic rod of the hydraulic device 1007 adjusts the position of the movable base plate 1003 through the large hole to adjust the internal pressure of the metal housing in real time. The hydraulic rod is equipped with a pressure display gauge for real-time monitoring of the internal pressure of the metal housing. A workbench 1008 is used to support the metal container and the hydraulic device 1007. A movable baffle 1012 is provided on the workbench 1008 to restrict the movement of the hydraulic device 1007 and the housing 1002, so that the pressure of the hydraulic device 1007 can be better transmitted to the housing.

[0028] like Figure 4 As shown, for 3D printed PEEK materials of different sizes, the metal container also includes an extension box 1009, which is connected to the box 1011 by a fixing plate 1010 and a insert.

[0029] Example 1: The present invention is based on the heat treatment method of the isostatic pressing device applicable to 3D printing PEEK materials described above, and includes the following steps:

[0030] (1) Place the fused deposition 3D printed PEEK material in an ultrasonic cleaner and clean the surface with anhydrous ethanol for 30 minutes; take out the cleaned 3D printed PEEK material and dry the surface with anhydrous ethanol using an ion air gun; place the dried PEEK material in a forced-air drying oven and dry it at 70°C for 60 minutes.

[0031] (2) Place spherical ceramic sand with a particle size of 100-150μm in a metal container and spread it flat as a medium for pressing the sample. The depth of the layer is 20mm. Place PEEK material on the surface of the ceramic sand, in the middle of the metal container. Continue to fill the metal container with ceramic sand until it exceeds the highest position of the material and spread it flat. Then fill it with another 20mm deep layer of ceramic sand, spread it flat, and compact the surface with a shovel. Cover the metal container with the top cover plate 1001 and use the manual screw 1006 to fix the end cap on the container.

[0032] Rotate the manual screw 1006 to move the movable base plate 1003 upward. After the movable base plate 1003 exerts a slight pre-tightening force on the PEEK material wrapped in ceramic sand, place the metal box sideways with the top plate close to the movable baffle 1012 of the workbench 1008. Start the hydraulic device 1007 to continue moving the movable base plate 1003 upward so that it exerts equal pressure on the ceramic sand inside the metal box. The pressure is set to 5 bar. After the pressure stabilizes, rotate the manual screw 1006 so that the bottom of the screw just contacts the base plate. Remove the hydraulic device. Place the entire box into a heat treatment furnace (muffle furnace) for heat treatment at a temperature of 250°C for 120 minutes. After the heat treatment is completed, allow it to cool naturally. Once the temperature is below 50°C, remove the box, open the metal box cover 1001, and remove the PEEK material for post-treatment, which is the same as step (1).

[0033] Comparative Example 1: The difference from Example 1 is that step (2) is not included.

[0034] Comparative Example 2: The difference from Example 1 is that step (2) does not include isostatic pressing, and the PEEK material is directly heat-treated.

[0035] The performance of the PEEK materials treated in Example 1 and Comparative Examples 1-2 was tested, and the results are shown in Table 1. Table 1 shows that the mechanical properties of the workpieces were improved to some extent after heat treatment. However, the density of the parts increased after isostatic pressing heat treatment, indicating that a certain pressure eliminated some of the porosity in the 3D printed PEEK material parts. With the elimination of porosity, mechanical properties such as tensile, bending, and cantilever beam impact strength were significantly improved.

[0036] Table 1. Summary of the performance of PEEK materials treated in Example 1 and Comparative Examples 1-2

[0037]

[0038] Example 2: The difference from Example 1 is that in step (2), the isostatic pressure is 10 bar and the heat treatment temperature is 280°C.

[0039] Comparative Example 3: The difference from Example 2 is that step (2) is not included.

[0040] Comparative Example 4: The difference from Example 2 is that step (2) does not include isostatic pressing; the PEEK material is directly heat-treated.

[0041] The performance of the PEEK materials treated in Example 2 and Comparative Examples 3-4 was tested, and the results are shown in Table 2. Table 2 shows that the mechanical properties of the workpieces improved to some extent after heat treatment. However, the density of the parts increased after isostatic pressing, indicating that the pressure eliminated some of the porosity in the 3D printed PEEK material parts. With the elimination of porosity, mechanical properties such as tensile, bending, and cantilever beam impact strength significantly improved. With further increases in pressure and temperature, compared with Example 1, the density of the samples further increased to almost complete densification, and the mechanical properties were further improved, with the most significant improvement in tensile and bending strength.

[0042] Table 2. Summary of the performance of PEEK materials treated in Example 2 and Comparative Examples 3-4

[0043]

[0044] Example 3: The difference from Example 1 is that in step (2), the isostatic pressure is 20 bar.

[0045] Comparative Example 5: The difference from Example 3 is that step (2) is not included.

[0046] Comparative Example 6: The difference from Example 3 is that step (2) does not include isostatic pressing, and the PEEK material is directly heat-treated.

[0047] Comparative Example 7: The difference from Example 3 is that the ceramic sand was replaced with stainless steel powder. Experimental results show that at high temperatures, stainless steel powder easily embeds into the sample surface, causing contamination that cannot be cleaned.

[0048] The performance of the PEEK materials treated in Example 2 and Comparative Examples 5-7 was tested, and the results are shown in Table 3.

[0049] Table 3. Summary of the performance of PEEK materials treated in Example 3 and Comparative Examples 5-6

[0050]

[0051] As shown in Table 3, compared with Example 2, in Example 3, with the temperature remaining constant, the density of the parts increased with further increase in pressure. Since this density was close to the theoretical density of PEEK material, the increase was not significant. Because the temperature remained constant, the crystallinity did not change, but the mechanical properties improved with further increase in density. The mechanical properties of the samples treated with stainless steel powder and ceramic sand were the same; however, because the high-temperature, high-pressure metal powder easily adhered to the surface of the PEEK material and was difficult to remove, it caused some contamination to the samples.

Claims

1. A method for isostatic pressing heat treatment of PEEK materials suitable for 3D printing, characterized in that, Includes the following steps: (1) PEEK material for fused deposition modeling is subjected to surface cleaning, static electricity removal and drying treatment; (2) Ceramic sand is used as the heat conduction and pressure transmission medium. First, the ceramic sand is spread evenly in the isostatic pressing device. Then, the dried fused deposition modeling (FDM) PEEK material is placed in the isostatic pressing device. The ceramic sand is then filled until it is completely covered. The isostatic pressing device is subjected to hydraulic treatment. After the pressure stabilizes, heat treatment is performed. The particle size of the ceramic sand is 20-100 μm. The depth of the ceramic sand spreading is 10-100 mm, and the depth of complete coverage is 10-100 mm. The pressure of the hydraulic treatment is 5-20 bar. The conditions for the heat treatment are: temperature 250-300℃, time 60-180 min. The isostatic pressing device suitable for 3D printing PEEK material includes a metal container, a hydraulic device (1007), and a worktable (1008). The metal container includes a box body (1008). 002), an upper cover plate (1001) set at the upper port of the box (1002), a movable base plate (1003) set inside the box (1002), a felt (1004) set between the movable base plates (1003), and a fixed base plate (1005) and a manual screw (1006) set at the lower port of the box (1002). The fixed base plate (1005) has small holes at its four corners for connecting and fixing with the manual screw (1006), and a large hole in the middle of the fixed base plate (1005) for docking with the hydraulic device (1007). The hydraulic rod of the hydraulic device (1007) adjusts the position of the movable base plate (1003) through the large hole to adjust the internal pressure of the metal box in real time. The workbench (1008) is used to support the metal container and the hydraulic device (1007).

2. The isostatic pressing heat treatment method for 3D printing PEEK materials according to claim 1, characterized in that, The ceramic sand comprises the following raw materials in parts by weight: 90-95 parts zirconium oxide and 5-10 parts silicon dioxide.

3. The isostatic pressing heat treatment method for 3D printing PEEK materials according to claim 1, characterized in that, The metal container also includes an extension box (1009) connected to the box (1002) via a fixing plate (1010) and a insert (1011).

4. The isostatic pressing heat treatment method for 3D printing PEEK materials according to claim 1, characterized in that, The workbench (1008) is provided with a movable baffle (1012) to restrict the movement of the hydraulic device (1007) and the housing (1002).

5. The isostatic pressing heat treatment method for 3D printing PEEK materials according to claim 1, characterized in that, The hydraulic rod is equipped with a pressure display gauge for real-time monitoring of the pressure inside the metal housing.

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