A method for preparing a TC4 titanium alloy acetabular cup based on an electron beam selective melting technology

Abstract

This invention discloses a method for manufacturing a TC4 titanium alloy acetabular cup based on electron beam selective melting (EBM) technology, belonging to the field of medical 3D printing technology. The method includes: TC4 alloy powder preparation; constructing a three-dimensional model of the acetabular cup containing the cup body and porous structure; model slicing and scanning path planning; vacuuming and helium filling before printing; preheating the substrate; powder spreading and electron beam preheating sintering; focusing the molten solid and porous structure according to the slicing data; post-heating the molten layer; repeating the powder spreading, sintering, melting, and heat-holding processes until the part is completed; vacuum cooling and removal of the part; and finally wire cutting, support removal, and surface treatment. This invention effectively reduces forming thermal stress and obtains a uniform microstructure through the preheating and post-heating processes of EBM technology. It also utilizes the powder sintering characteristics to achieve fine forming of the porous structure, significantly improving the mechanical properties, dimensional accuracy, and production efficiency of the TC4 titanium alloy acetabular cup, and extending the prosthesis's service life.

Description

Technical Field

[0001] This invention relates to the field of medical 3D printing, specifically to a method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology. Background Technology

[0002] Electron beam selective melting (EBM) is an advanced additive manufacturing technology widely used in biomedical, aerospace, and high-end equipment manufacturing fields. Compared with traditional material processing methods, EBM offers advantages such as high power, high energy utilization, high vacuum protection, and fast processing speed, making it an ideal manufacturing technology for complex parts made of high-performance titanium alloys and other high-melting-point reactive metals. Titanium alloys possess low density, high strength, and good biocompatibility, but their narrow processing window and complex processing steps severely limit their widespread application.

[0003] Currently, acetabular cups are mostly fabricated using selective laser melting (SLM). However, SLM technology generates significant thermal stress during processing, which can easily lead to deformation or even cracking of thin-walled or porous structures, and its energy utilization rate is relatively low.

[0004] SLM and EBM technologies have higher energy efficiency, and their unique powder bed preheating process can effectively reduce thermal stress and temperature gradient during the molding process. This has significant advantages for acetabular cup prostheses that contain complex porous structures and require good mechanical properties and dimensional accuracy. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing TC4 titanium alloy acetabular cups based on electron beam selective melting technology. The aim is to reduce the thermal stress of the material through the preheating process unique to EBM technology, improve the strength and dimensional accuracy of the acetabular cup, especially its porous structure, and thus extend the service life of the acetabular cup prosthesis.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide the following technical solution: a method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology, comprising the following steps: S1 and TC4 alloy powder preparation: TC4 alloy powder with a particle size range of 45-105μm was selected and dried. S2. Use UG 3D modeling software to construct a 3D digital model of the cup body and porous structure of the acetabular cup to be prepared; S3. Use Magics data processing software to add support to the acetabular cup body; S4. Use ArtSpace segmentation software to slice and layer the three-dimensional digital model, plan the electron beam scanning path, and import it into the control software of the electron beam powder bed melting equipment. S5. Place the TC4 alloy powder and the substrate into the electron beam equipment to complete the leveling preparation, and evacuate the gun chamber and forming chamber and fill them with a certain amount of helium. S6. Preheat the substrate using a discrete electron beam scanning line to bring it to a preset temperature; S7. TC4 alloy powder of a predetermined thickness is laid on the preheated substrate, and the powder is preheated and sintered using a discrete electron beam. S8. Based on the slice data, use a focused electron beam to melt and shape the powder of the current layer to form a solid layer with the same shape as the slice of the current layer. S9. The molten surface is subjected to post-heat preservation treatment using discrete electron beams. S10. Lower the substrate by one slice thickness, and repeat steps S7 to S9 until the entire acetabular cup part is printed. S11. After cooling to a predetermined temperature under vacuum conditions, remove the formed acetabular cup part; S12. Use wire cutting to separate the part from the substrate, remove the support on the acetabular cup, and polish and sandblast the surface.

[0007] Further, in step S1, the TC4 alloy powder includes 6% Al, 4% V, ≤1% trace elements and the balance Ti by atomic percentage; the drying process involves placing the TC4 alloy powder in a vacuum drying oven, drying it at 200°C for 2 hours, and then cooling it to room temperature in the furnace.

[0008] Furthermore, in step S4, the slice thickness is 40–60 μm; when planning the scanning path, the fill line spacing is set to 3–5 mm, and the fill line width is 100–300 μm.

[0009] Furthermore, in step S5, the forming chamber is evacuated to a vacuum level of 10. -2 ~10 -3 After applying MPa, helium is introduced. The vacuum level inside the molding chamber is then controlled to be 10. -1 ~10 -2 MPa.

[0010] Furthermore, in step S6, the electron beam scanning speed for substrate preheating is 30-35 m / s.

[0011] Furthermore, in step S6, the preset temperature of the substrate is 600°C to 700°C.

[0012] Furthermore, in step S7, the thickness of the TC4 alloy powder is 60-80 μm; the process parameters for the preheating sintering are: electron beam defocusing amount of 0.05-0.1V, preheating beam current of 30-40 mA, and preheating time of 20-30 s.

[0013] Furthermore, in step S8, different melting process parameters are used for the solid part of the acetabular cup and the porous structure part: The melting process parameters for the solid part are: electron beam defocusing amount of -0.005 to 0V, scanning beam current of 10 to 20mA, scanning speed of 4 to 5m / s, and channel spacing of 90 to 110μm; The melting process parameters for the porous structure are: electron beam defocusing amount of -0.005 to 0V, scanning beam current of 2 to 3 mA, and scanning speed of 0.5 to 1 m / s.

[0014] Furthermore, in step S9, the process parameters for post-heat preservation are: electron beam defocusing amount of 0.05-0.1V, beam current of 30-40mA, and heat preservation time of 20-30s.

[0015] Furthermore, in step S3, the angle of the surface to be supported by the support structure is set to 30° to 60°, and the width of the fill line is set to 3 to 5 mm.

[0016] The beneficial effects of the above-described technical solution of the present invention are as follows: 1. This invention employs electron beam selective melting technology, employing substrate preheating, powder preheating, and post-printing heat preservation processes to ensure the part remains at a high temperature throughout the forming process, followed by slow cooling after forming. This is equivalent to performing "in-situ" heat treatment on each printed layer, effectively eliminating internal stress, preventing crack formation, and promoting the full growth of microstructures to form columnar crystals or fine lamellar structures that are beneficial to mechanical properties, thereby improving the strength of the material.

[0017] 2. The EBM technology of this invention utilizes the sintering characteristics of powder at high temperatures, allowing unmelted powder to form a "powder block" with a certain strength, possessing the function of powder self-support. This facilitates the fine forming and stacking printing of complex porous structures, significantly reduces the addition of extra supports, ensures the structural strength and shape accuracy of the porous structure of the acetabular cup, and extends the service life of the prosthesis.

[0018] 3. By optimizing the substrate preheating temperature (e.g., 650℃), this invention avoids part size deviation caused by substrate thermal deformation due to excessive temperature. At the same time, combined with precise powder management and process parameter control, it ensures the overall dimensional stability and forming effect of the acetabular cup. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention.

[0020] Figure 2 This is a schematic diagram of an electron beam 3D printed acetabular cup structure.

[0021] Figure 3 A diagram of an acetabular cup with dimensional deviation. Detailed Implementation

[0022] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0023] Example 1 Combination Figure 1 As shown, this invention proposes an electron beam 3D printing method for a TC4 titanium alloy acetabular cup, comprising the following steps: S1. Preparation of TC4 alloy powder for printing; TC4 alloy powder includes 6% Al, 4% V, ≤1% trace elements and the remainder Ti by atomic percentage, and the particle size range of TC4 alloy powder is 45~105μm. Place the TC4 alloy powder in a vacuum drying oven at 200℃ for 2h. After drying, turn off the power and let the TC4 alloy powder cool to room temperature with the vacuum drying oven before adding it to the powder tank.

[0024] S2. Use UG 3D modeling software to create a 3D digital model of the overall acetabular cup body and porous structure.

[0025] S3. Use Magics data processing software to add support to the acetabular cup body; add block support to the suspended part of the acetabular cup, and set the support surface angle to 30°~60° and the fill line width to 3~5mm in Magics data processing software.

[0026] S4. Use ArtSpace segmentation software to slice the model into layers and plan the scanning path, and import it into the control software of the electron beam powder bed melting equipment; the segmentation thickness of the acetabular cup 3D digital model is 40~60um, and the fill line spacing is set to 3~5mm and the fill line width is 100~300mm in ArtSpace segmentation software.

[0027] S5. Place the TC4 alloy powder and substrate into the electron beam equipment for leveling preparation. Evacuate the gun chamber and forming chamber and fill with a certain amount of helium. Clean the forming chamber, level the substrate, and evacuate the forming chamber. When the vacuum degree of the forming chamber reaches 10... -2 ~10 -3 Helium was introduced at a pressure of MPa, resulting in a vacuum of 10. -1 ~10 -2 MPa.

[0028] S6. The substrate is preheated using discrete electron beam scanning lines; the electron beam scanning speed for substrate preheating is 30~35m / s, and the preset temperature of the substrate is 600°C~700°C.

[0029] S7. A predetermined thickness of TC4 alloy powder is laid on the substrate, and the powder bed is preheated and sintered using a discrete electron beam. The thickness of the TC4 alloy powder is 60~80um, and excess powder is sent to the powder drop hopper by a scraper. The electron beam defocusing amount during preheating is 0.05~0.1V, the preheating beam current is 30-40mA, and the preheating time is 20~30s.

[0030] S8. Based on the slice data, a focused electron beam is used to melt and shape the single-layer powder; The electron beam defocusing amount for solid melting of the acetabular cup is -0.005~0V, the scanning beam current is 10~20mA, the scanning speed is 4~5m / s, and the track spacing is 90~110um.

[0031] The porous structure of the acetabular cup has an electron beam defocus of -0.005~0V, a scanning beam current of 2~3mA, and a scanning speed of 0.5~1m / s.

[0032] S9. The molten surface is post-heated using a discrete electron beam; the electron beam defocusing amount during post-heating is 0.05~0.1V, the beam current is 30~40mA, and the holding time is 20~30s.

[0033] S10. Lower the substrate by one slice thickness, and repeat S7-S9 until the entire acetabular cup part is printed.

[0034] S11. Cool the acetabular cup part to below 50°C under vacuum conditions, remove the part, and use a powder recovery system to clean and recover residual powder from the surface and gaps of the part.

[0035] S12. Use wire cutting to separate the part from the substrate, remove the support on the acetabular cup, and polish and sandblast the surface. Figure 2 This is a schematic diagram of an electron beam 3D printed acetabular cup structure.

[0036] Example 2 This invention provides an electron beam 3D printing method for a TC4 titanium alloy acetabular cup, comprising the following steps: Preparation of S1 and TC4 alloy powders: TC4 alloy powders contain 6% Al, 4% V, ≤1% trace elements, and the remainder Ti by atomic percentage, and the particle size range of TC4 alloy powders is 45~105μm. The TC4 alloy powders are dried in a vacuum drying oven at 200℃ for 2 hours. After drying, the power is turned off, and the TC4 alloy powders are cooled to room temperature with the vacuum drying oven before being added to the powder container.

[0037] S2. Establish a three-dimensional digital model of the acetabular cup to be printed. Import the established three-dimensional digital model into the slicing software for slicing. The slice thickness is 50μm. Then import the slicing results into the control software of the electron beam printing equipment.

[0038] S3. Clean the forming chamber and level the substrate. Evacuate the forming chamber until the air pressure reaches 10. -3 Helium was introduced at MPa and the pressure was stabilized at 10 MPa. -1 High pressure is activated at MPa.

[0039] S4. The substrate in the forming chamber is preheated using an electron beam. The electron beam defocusing amount is 0.05V, the scanning speed is 35m / s, and the preset temperature is 650℃.

[0040] S5. Use a scraper to spread the TC4 powder in the powder cylinder onto the substrate, with a preset powder layer thickness of 80μm.

[0041] S6. Preheat the powder bed using an electron beam with a defocusing amount of 0.05V. The preheating parameters are configured as follows: preheating current of 40mA, preheating time of 30s, and scanning speed of 35m / s. Melt and sinter the cross-section of the part using a focused electron beam with a defocusing amount of -0.005V. Solid melting parameters are configured as follows: melting current of 12mA, scanning speed of 5m / s, and channel spacing of 100μm; porous structure melting parameters are configured as follows: melting current of 2.4mA, scanning speed of 1m / s, and offset of 40μm; support melting parameters are configured as follows: melting current of 2.4mA and scanning speed of 1m / s. After melting, post-heating is performed on the powder bed using an electron beam with a defocusing amount of 0.05V. The post-heating parameters are configured as follows: heat-holding current of 35mA and heat-holding time of 25s.

[0042] S7, Rotation scanning direction, the substrate descends by one powder coating thickness.

[0043] S8. Repeat steps S5, S6 and S7 until the acetabular cup is printed.

[0044] Example 3 This invention provides an electron beam 3D printing method for a TC4 titanium alloy acetabular cup, which differs from Example 1 in that: In S4, an electron beam is used to preheat the substrate in the forming chamber. The electron beam defocusing amount is 0.05V, the scanning speed is 35m / s, and the preset temperature is 700℃. The melting parameters for the porous structure in S6 are configured as follows: melting current of 2.5mA, scanning speed of 0.8m / s, and no offset; the melting parameters for the support are configured as follows: melting current of 2.4mA and scanning speed of 1m / s. Except for the steps described above, the parameters for all other steps are the same as in Example 2.

[0045] Comparative analysis showed that in Example 3, the substrate preheating temperature was 700℃. During the printing process, the stainless steel substrate deformed due to thermal expansion, resulting in a displacement of the acetabular cup size. In Example 2, the substrate preheating temperature was 650℃, effectively preventing this displacement of the acetabular cup size. Figure 3 The diagram shows the acetabular cup structure with dimensional deviations. Furthermore, the porous structure printing process in Example 3 lacked outer contour scanning, resulting in lower strength and breakage. In contrast, the porous structure used in Example 2 had uniform pore size and higher strength. In summary, the acetabular cup printed using the parameters of Example 2 has a complete overall structure and support, accurate dimensions, and better forming effect.

[0046] Table 1. Achilles cup size offset Table 2. Room temperature tensile properties of acetabular cups In summary, this invention utilizes a unique preheating process in electron beam printing (EBM) to reduce thermal stress in the material. The part remains at a high temperature throughout the forming process and cools slowly afterward. This process is equivalent to performing an "in-situ" heat treatment on each printed layer, effectively eliminating internal stress, preventing cracks, and allowing the microstructure to grow fully. Furthermore, the characteristics of EBM processes allow the material to form columnar crystals or fine lamellar structures. This directional solidification grain structure, similar to the fibrous flow lines of forgings, effectively hinders dislocation movement, thereby enhancing the material's strength.

[0047] Secondly, electron beam dot printing technology utilizes the sintering characteristics of powder. At high temperatures, a slight metallurgical bond occurs between powder particles, causing the unmelted powder to form a "powder block" with a certain strength. This provides the powder with self-supporting capabilities, enabling the precise shaping and stacking printing of porous materials. This further reduces the amount of support required and allows for stable printing of suspended or complex areas of the acetabular cup, significantly improving production efficiency. Therefore, this invention improves the strength of the porous structure of the acetabular cup through EBM forming technology, extends the service life of the acetabular cup prosthesis, and significantly improves the production efficiency of the acetabular cup.

[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology, characterized in that, Includes the following steps: S1 and TC4 alloy powder preparation: TC4 alloy powder with a particle size range of 45-105μm was selected and dried. S2. Use UG 3D modeling software to construct a 3D digital model of the cup body and porous structure of the acetabular cup to be prepared; S3. Use Magics data processing software to add support to the acetabular cup body; S4. Use ArtSpace segmentation software to slice and layer the three-dimensional digital model, plan the electron beam scanning path, and import it into the control software of the electron beam powder bed melting equipment. S5. Place the TC4 alloy powder and the substrate into the electron beam equipment to complete the leveling preparation, and evacuate the gun chamber and forming chamber and fill them with a certain amount of helium. S6. Preheat the substrate using a discrete electron beam scanning line to bring it to a preset temperature; S7. TC4 alloy powder of a predetermined thickness is laid on the preheated substrate, and the powder is preheated and sintered using a discrete electron beam. S8. Based on the slice data, use a focused electron beam to melt and shape the powder of the current layer to form a solid layer with the same shape as the slice of the current layer. S9. The molten surface is subjected to post-heat preservation treatment using discrete electron beams. S10. Lower the substrate by one slice thickness, and repeat steps S7 to S9 until the entire acetabular cup part is printed. S11. After cooling to a predetermined temperature under vacuum conditions, remove the formed acetabular cup part; S12. Use wire cutting to separate the part from the substrate, remove the support on the acetabular cup, and polish and sandblast the surface.

2. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S1, the TC4 alloy powder comprises 6% Al, 4% V, ≤1% trace elements and the balance Ti by atomic percentage; the drying process involves placing the TC4 alloy powder in a vacuum drying oven, drying it at 200°C for 2 hours, and then cooling it to room temperature in the furnace.

3. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S4, the slice thickness is 40-60 μm; when planning the scanning path, the fill line spacing is set to 3-5 mm and the fill line width is 100-300 μm.

4. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S5, the forming chamber is evacuated to a vacuum level of 10. -2 ~10 -3 After applying MPa, helium is introduced. The vacuum level inside the molding chamber is then controlled to be 10. -1 ~10 -2 MPa.

5. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S6, the electron beam scanning speed for substrate preheating is 30-35 m / s.

6. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 5, characterized in that, In step S6, the preset temperature of the substrate is 600°C to 700°C.

7. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S7, the thickness of the TC4 alloy powder is 60-80 μm; the process parameters for preheating sintering are: electron beam defocusing amount of 0.05-0.1V, preheating beam current of 30-40 mA, and preheating time of 20-30 s.

8. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S8, different melting process parameters are used for the solid part and the porous structure part of the acetabular cup: The melting process parameters for the solid part are: electron beam defocusing amount of -0.005 to 0V, scanning beam current of 10 to 20mA, scanning speed of 4 to 5m / s, and channel spacing of 90 to 110μm; The melting process parameters for the porous structure are: electron beam defocusing amount of -0.005 to 0V, scanning beam current of 2 to 3 mA, and scanning speed of 0.5 to 1 m / s.

9. A method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1 or 8, characterized in that, In step S9, the post-heating process parameters are: electron beam defocusing amount of 0.05-0.1V, beam current of 30-40mA, and heat preservation time of 20-30s.

10. The method for preparing a TC4 titanium alloy acetabular cup based on electron beam selective melting technology according to claim 1, characterized in that, In step S3, the angle of the surface to be supported by the support structure is set to 30° to 60°, and the width of the fill line is set to 3 to 5 mm.

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