Electron beam selective melting forming equipment and forming method

Abstract

The application discloses an electron beam selective melting forming equipment and a forming method, and belongs to the field of additive manufacturing. The equipment comprises a vacuum cabin, an electron beam gun, a powder feeding system and a forming cylinder. The electron beam gun is fixedly arranged above the vacuum cabin through an alloy support, and the electron beam gun and the vacuum cabin are kept sealed. A gas cylinder is arranged at the top of the vacuum cabin, the gas cylinder is connected with a heat insulation cabin, powder feeding systems are arranged on the two sides of the heat insulation cabin, a flexible scraper is arranged below the powder feeding systems, and a substrate and a heat insulation layer constitute the forming cylinder. The application can process high-temperature titanium alloy, the preheating time of the electron beam gun is reduced through heat preservation by using the heat insulation layer, the preheating precision of the electron beam gun at high temperature is ensured, and the internal quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing, and specifically relates to an electron beam selective melting forming equipment and forming method. Background Technology

[0002] Additive manufacturing (also known as 3D printing) is a high-end digital manufacturing technology that has developed rapidly in recent years. Titanium alloy powder metal 3D printing technology mainly consists of three technologies: Laser Material Delivery (LMD), Laser Spread Molding (SLM), and Selective Electron Beam Melting (EBSM). Among them, EBSM uses high-speed electrons to bombard titanium alloy powder, converting the kinetic energy into heat to melt the powder, thus printing the desired shape layer by layer. Electron beam additive manufacturing has advantages such as high forming temperature, low thermal stress, minimal support addition, high forming efficiency, and low pollution, making it suitable for high-precision integrated forming of high-temperature, high-strength metal materials.

[0003] Titanium alloys possess advantages such as light weight, high strength, and corrosion resistance, making them widely used in the aerospace field. Currently, TC4 is a commonly used titanium alloy grade in the aerospace industry, with an operating temperature reaching 300-400℃. However, the rapid development of aerospace vehicles demands components with lightweight, high-temperature resistance, and high reliability. The high-temperature load-bearing capacity of TC4 titanium alloy has reached its design limit and is insufficient to meet future needs. Therefore, the additive manufacturing field urgently needs to develop titanium alloy materials and forming processes with higher temperature resistance, such as Ti60, Ti65, and TiAl. However, due to the inherent brittleness of high-temperature titanium alloys, selective laser melting (SLM) is prone to metallurgical quality defects such as hot cracking. Furthermore, the large heat input during forming can lead to significant deformation when fabricating complex thin-walled components. Electron beam selective melting (EBM) of high-temperature titanium alloys can effectively solve problems such as hot cracking during forming, making it an ideal process for fabricating high-temperature titanium alloy components for aerospace applications. However, ELM still faces challenges such as the loss of low-melting-point elements, low forming efficiency, low forming accuracy, and poor internal quality, requiring systematic process design to address these issues.

[0004] Among existing forming equipment, Chinese invention patent: A method for preparing TA15 titanium alloy thin-walled components using electron beam selective forming technology, application publication number: CN119952076A, discloses: Step 1, preparing TA15 titanium alloy powder. A titanium alloy rod with a diameter of 50mm is loaded into a plasma rotating electrode atomization powder-making device, and a mixed gas is introduced for atomization powder preparation; wherein, the distance between the plasma gun and the electrode rod is 45mm, the power is 110kW, the atomization speed is 2.1kg / min, and the pressure is 2MPa. The melting temperature is 1800℃ and the vacuum degree is 0.6×10⁻⁶. -3The powder was dried in a drying oven at 115℃~125℃ for later use. Then, the dried alloy powder was sieved using 50μm and 100μm mesh sieves to obtain TA15 titanium alloy powder. Step 2: Constructing a 3D model of the TA15 titanium alloy thin-walled component. The 3D machining platform and machining part were constructed sequentially using the MaterialiseMagics software from Silron. The model size of the machining part was 40mm×40mm×2.5mm. The SL-EBM BuildPrepare software was then used to slice the 3D model of the machining part to obtain data. The data was then used for path planning to generate an STL format file, which was imported into the electron beam selective melting equipment. The slice thickness during electron beam forming was set to 50μm.

[0005] The aforementioned existing technology has the following problems:

[0006] 1. Using existing technologies to process high-temperature titanium alloys; for high-precision components, electron beam selective melting forming of high-temperature titanium alloys is prone to problems such as loss of low-melting-point elements, low forming efficiency, low forming accuracy, and poor internal quality during high-temperature processing.

[0007] 2. Using existing technology for preheating results in long preheating and printing times, and accelerates the loss of low-melting-point elements during the molding process, leading to the formation of microcracks and defects inside the molded part.

[0008] 3. During long-term printing in a high-temperature and high-vacuum environment, the electron beam gun is prone to mechanical displacement under stress, resulting in a decrease in forming accuracy. Summary of the Invention

[0009] The purpose of this invention is to overcome the aforementioned problems and propose an electron beam selective melting forming equipment and forming method to solve the problems of low melting point element loss, low forming efficiency, low forming accuracy, and poor internal quality in the processing of high-precision mechanical parts by electron beam selective melting forming of high-temperature titanium alloys.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] An electron beam selective melting forming equipment is characterized by comprising a vacuum chamber, an electron beam gun, a powder feeding system, and a forming cylinder; the electron beam gun is fixedly mounted above the vacuum chamber via an alloy support, and the electron beam gun and the vacuum chamber are kept sealed; a cylinder is provided at the top of the vacuum chamber and is connected to a heat insulation chamber; a powder feeding system is provided on both sides of the heat insulation chamber; a flexible scraper is provided below the powder feeding system; and a substrate and a heat insulation layer constitute the forming cylinder.

[0012] The electron beam gun and the vacuum chamber are sealed together by a bellows.

[0013] The alloy support has an expansion coefficient of 3.5~5.0×10⁻⁶. -6 Iron-nickel alloy support at / ℃.

[0014] The heat insulation chamber is made of stainless steel or molybdenum alloy thin plates.

[0015] The powder feeding system includes a powder box, a rotating shaft, and a flexible scraper; the rotating shaft is located at the bottom of the powder box and has a powder trough embedded in it. By rotating the rotating shaft, the titanium alloy powder in the powder box falls onto the front of the flexible scraper.

[0016] The flexible scraper is mounted on a horizontal moving device, which controls the horizontal movement of the flexible scraper.

[0017] The flexible scraper is made of nickel-iron alloy sheet.

[0018] The surface of the flexible scraper is coated with diamond or tungsten carbide.

[0019] The heat insulation layer includes an iron-nickel alloy layer, a heat insulation material layer, and a water-cooling layer. The heat insulation material layer is composed of glass fiber, asbestos, and alumina ceramic.

[0020] The base plate is mounted on a lifting rod, which controls the base plate's ascent and descent.

[0021] An electron beam selective melting forming method, characterized by the following specific steps:

[0022] Step s1: Vacuum the vacuum chamber and lower the heat insulation chamber;

[0023] Step s2: Preheat and maintain the substrate temperature using an electron beam gun;

[0024] Step s3: After the heat preservation is completed, the powder feeding system delivers titanium alloy powder to the front of the flexible scraper, raises the substrate to the powder bed position, and lifts the heat insulation chamber.

[0025] Step s4: The flexible scraper moves horizontally towards the powder bed position to lay titanium alloy powder on the substrate;

[0026] Step s5: Lower the heat shield and preheat the titanium alloy powder with an electron beam gun;

[0027] Step s6: After preheating, the titanium alloy powder is scanned, filled, and sintered using an electron beam gun.

[0028] Step s7: Repeat steps s3, s4, s5 and s6 to complete the printing of the titanium alloy part;

[0029] Step s8: Inert gas is introduced into the vacuum chamber to cool it down and remove residual titanium alloy powder and supports from the titanium alloy parts;

[0030] Step s9: Heat treat the titanium alloy parts and grind and polish them to obtain the titanium alloy parts.

[0031] In step s1, the vacuum level in the vacuum chamber is evacuated to 10. -3 Below Pa.

[0032] In step s2, the substrate is preheated to 700~1200℃ and kept at that temperature for 30~60 minutes.

[0033] In step s5, when the titanium alloy powder is preheated, the substrate in the powder bed position is divided into a forming sintering zone, a transition zone, and an unsintered zone. Preheating is carried out in the order of the first stage unsintered zone, the second stage forming sintering zone and transition zone, and the third stage forming sintering zone.

[0034] During the preheating of the titanium alloy powder, the electron beam gun scans the unsintered area in the first stage three times, the sintered area and transition area in the second stage four times, and the sintered area in the third stage once.

[0035] In step s8, the vacuum chamber is cooled to below 50°C.

[0036] The advantages of using this invention are:

[0037] Compared with existing technologies, this invention can process high-temperature titanium alloys. By utilizing a heat insulation layer to reduce the preheating time of the electron beam gun, the preheating accuracy of the electron beam gun at high temperatures is ensured. The heat insulation layer of the forming cylinder improves the heat preservation performance after preheating. The flexible scraper makes the powder spreading more uniform, shortens the preheating time, ensures preheating accuracy, improves efficiency, and reduces the loss of low-melting-point elements. At the same time, the heat treatment after forming optimizes the microstructure and mechanical properties, improving the internal quality.

[0038] 2. The heat insulation layer is composed of heat insulation materials such as fiberglass, asbestos, and alumina ceramics to maintain the high temperature of the forming chamber and reduce the preheating time of the electron beam gun.

[0039] Third, the function of the iron-nickel alloy layer is to prevent the thermal expansion and deformation of the forming chamber under high temperature environment from affecting the forming accuracy.

[0040] IV. The water-cooling layer is a stainless steel plate with internal flow channels. Its function is to reduce the external temperature of the forming cylinder of the equipment and prevent thermal deformation of the mechanical structure of the forming chamber from affecting the lifting and lowering of the substrate.

[0041] 5. The surface of the flexible scraper is treated with diamond or tungsten carbide plating to improve the scraper's service life.

[0042] VI. This method reduces the loss of low-melting-point elements, resulting in an internal defect density of ≤0.5% in the high-temperature titanium alloy. Metallographic images are attached. Figure 3 As shown, the forming accuracy of the part can reach 0.1mm / 100mm. The room temperature tensile strength of the part is ≥1100MPa, and the elongation is ≥10%; the 600℃ tensile strength is ≥650MPa, and the elongation is ≥12%.

[0043] 7. The use of inert gas for cooling can quickly reduce the temperature of high-temperature titanium alloy forming parts while ensuring safety during the cooling process. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the electron beam selective melting and forming equipment of the present invention;

[0045] Figure 2 This is a schematic diagram of the substrate preheating scanning area of ​​the present invention;

[0046] Figure 3 Metallographic images of Ti60 high-temperature titanium alloy formed by electron beam selective melting according to the present invention.

[0047] Reference numerals: 1. Vacuum chamber; 2. Electron beam gun; 3. Powder feeding system; 4. Forming cylinder; 5. Alloy support; 6. Cylinder; 7. Insulation chamber; 8. Flexible scraper; 9. Substrate; 10. Insulation layer; 11. Corrugated pipe; 12. Forming and sintering zone; 13. Transition zone; 14. Unsintered zone; 15. Powder box; 16. Rotating shaft; 17. Electrical control cabinet; 18. Powder bed position; 19. Lifting rod. Detailed Implementation

[0048] Example 1

[0049] An electron beam selective melting forming apparatus includes a vacuum chamber 1, an electron beam gun 2, a powder feeding system 3, and a forming cylinder 4. The electron beam gun 2 is fixedly mounted above the vacuum chamber 1 via an alloy support 5, and the electron beam gun 2 and the vacuum chamber 1 are kept sealed. A cylinder 6 is provided on the top of the vacuum chamber 1, and the cylinder 6 is connected to a heat insulation chamber 7. The powder feeding system 3 is provided on both sides of the heat insulation chamber 7, and a flexible scraper 8 is provided below the powder feeding system 3. The forming cylinder 4 is composed of a substrate 9 and a heat insulation layer 10.

[0050] The electron beam gun 2 and the vacuum chamber 1 are sealed together by a bellows 11.

[0051] The alloy support 5 has an expansion coefficient of 3.5~5.0×10⁻⁶. -6 Iron-nickel alloy support at / ℃.

[0052] The heat insulation chamber 7 is made of stainless steel or molybdenum alloy thin plates.

[0053] The powder feeding system 3 includes a powder box 15, a rotating shaft 16, and a flexible scraper 8. The rotating shaft 16 is located at the bottom of the powder box 15 and has a powder trough embedded in it. By rotating the rotating shaft 16, the titanium alloy powder in the powder box 15 is dropped in front of the flexible scraper 8.

[0054] The flexible scraper 8 is equipped with a horizontal moving device, which controls the horizontal movement of the flexible scraper 8.

[0055] The flexible scraper 8 is a flexible scraper made of nickel-iron alloy sheet.

[0056] The flexible scraper 8 is coated with diamond or tungsten carbide.

[0057] The heat insulation layer 10 includes an iron-nickel alloy layer, a heat insulation material layer, and a water-cooling layer. The heat insulation material layer is composed of glass fiber, asbestos, and alumina ceramic.

[0058] The substrate 9 is mounted on the lifting rod 19, and the lifting rod 19 controls the substrate 9 to rise and fall.

[0059] Step s1: Vacuum chamber 1 is evacuated, and heat insulation chamber 7 is lowered;

[0060] Step s2: Preheat and maintain the temperature of the substrate 9 using the electron beam gun 2;

[0061] Step s3: After the heat preservation is completed, the powder feeding system 3 sends the titanium alloy powder to the front of the flexible scraper 8, raises the substrate 9 to the powder bed position 18, and lifts the heat insulation chamber 7.

[0062] Step s4: The flexible scraper 8 moves horizontally to the powder bed position 18 to lay titanium alloy powder on the substrate 9;

[0063] Step s5: Lower the heat insulation chamber 7 and preheat the titanium alloy powder with the electron beam gun 2;

[0064] Step s6: After preheating, the titanium alloy powder is scanned, filled, and sintered using an electron beam gun 2.

[0065] Step s7: Repeat steps s3, s4, s5 and s6 to complete the printing of the titanium alloy part;

[0066] Step s8: Inert gas is introduced into the vacuum chamber 1 to cool it down and remove residual titanium alloy powder and supports from the titanium alloy parts;

[0067] Step s9: Heat treat the titanium alloy parts and grind and polish them to obtain the titanium alloy parts.

[0068] In step s1, the vacuum chamber 1 is evacuated to a vacuum level of 10. -3 Below Pa.

[0069] In step s2, the substrate 9 is preheated to 700~1200℃ and kept at that temperature for 30~60 minutes.

[0070] In step s5, when the titanium alloy powder is preheated, the substrate 9 located in the powder bed position 18 is divided into a forming sintering zone 12, a transition zone 13, and an unsintered zone 14. Preheating is carried out in the following order: the first stage unsintered zone 14, the second stage forming sintering zone 12 and transition zone 13, and the third stage forming sintering zone 12.

[0071] During the preheating of the titanium alloy powder, the electron beam gun 2 scans the unsintered region 14 in the first stage 3 times, the forming sintered region 12 and the transition region 13 in the second stage 4 times, and the forming sintered region 12 in the third stage 1 once.

[0072] In step s8, the vacuum chamber 1 is cooled to below 50°C.

[0073] like Figure 1 As shown, an electron beam selective melting and forming equipment includes: a vacuum chamber 1; an electron beam gun 2; a powder feeding system 3; and a forming cylinder 4. The machinable high-temperature titanium alloys include, but are not limited to, near-α phase titanium alloys, titanium-aluminum alloys, and titanium-aluminum-niobium alloys. The electron beam gun 2 is flexibly sealed to the vacuum chamber 1 using a bellows 11. A low-thermal-expansion-coefficient iron-nickel alloy support is used to fix it above the vacuum chamber to prevent the electron beam gun 2 from shifting due to the high vacuum and high-temperature environment, which would reduce forming accuracy. The low thermal expansion coefficient of the iron-nickel alloy support ranges from 3.5 to 5.0 × 10⁻⁶. -6 / ℃.

[0074] The vacuum chamber 1 has a liftable heat insulation chamber 7 between the forming cylinder 4 and the electron beam gun 2. The heat insulation chamber 7 is connected to the top of the vacuum chamber 1 via a cylinder 6. Its working principle is as follows: when the electron beam gun 2 preheats the titanium alloy powder bed or sintersting titanium alloy powder, the heat insulation chamber 7 descends to cover the powder bed position 18 to achieve a heat preservation effect; when the electron beam gun 2 stops working, the heat insulation chamber 7 rises, allowing the scraper to complete the powder spreading work through the upper end of the forming cylinder 4.

[0075] The heat insulation chamber 7 is composed of multiple layers of stainless steel or molybdenum alloy sheets, with an opening at the top, allowing the electron beam emitted by the electron beam gun 2 to preheat the titanium alloy powder on the substrate 9 through the heat insulation chamber 7; the inner sheet metal of the heat insulation chamber 7 is removable, making it convenient to change the type of inner heat insulation sheet metal according to the forming material.

[0076] To ensure the accuracy of the powder coating thickness under high temperature conditions, the scraper is a flexible scraper made of nickel-iron alloy sheet 8; to improve the service life of the scraper, the scraper surface is treated with diamond or tungsten carbide plating.

[0077] The forming cylinder 4 consists of an iron-nickel alloy layer, a heat insulation layer 10, and a water-cooling layer from the inside out. The iron-nickel alloy layer is used to prevent the thermal expansion and deformation of the forming chamber under high temperature conditions from affecting the forming accuracy. The heat insulation layer 10 is composed of heat insulation materials such as glass fiber, asbestos, and alumina ceramic. Its function is to maintain the high temperature of the forming chamber and reduce the preheating time of the electron beam gun 2. The water-cooling layer is a stainless steel plate with internal flow channels. Its function is to reduce the external temperature of the forming cylinder 4 and prevent the thermal deformation of the mechanical structure of the forming chamber from affecting the lifting and lowering of the substrate 9. The substrate 9 is connected to the lifting rod 19, which receives commands to drive the substrate 9 to lift and lower.

[0078] The electron beam selective melting forming equipment is connected to an external electrical control cabinet 17. The electrical control cabinet 17 is responsible for providing power to the electron beam gun 2 and providing operating instructions to the vacuum chamber 1, electron beam gun 2, powder feeding system 3, flexible scraper 8 and lifting rod 19.

[0079] Example 2

[0080] like Figure 2 As shown, taking Ti60 high-temperature titanium alloy as an example, Ti60 titanium alloy powder prepared by rotating electrode is selected as raw material. The actual composition of titanium alloy powder is Ti-6.2Al-3.9Sn-0.54Mo-1.05Nb-0.99Ta-3.1Zr-0.45Si-0.05C, and the particle size range of titanium alloy powder is 53~106μm.

[0081] Before printing Ti60 high-temperature titanium alloy, the equipment vacuum level should be evacuated to 10. -3 The substrate 9 is heated to 800-850°C using an electron beam gun 2, and then held at that temperature for 30 minutes. The heating parameters for the substrate 9 are: accelerating voltage 60KV, electron beam spot diameter 1mm, scanning spacing 1mm, scanning speed 50m / s, and beam current 90mA. The holding parameters for the substrate 9 are: accelerating voltage 60KV, electron beam spot diameter 1mm, scanning spacing 1mm, scanning speed 50m / s, and beam current 70mA. During the preheating and holding processes of the substrate 9, the heat insulation chamber 7 is in a descending state.

[0082] After the substrate 9 is insulated, the powder feeding system 3 delivers titanium alloy powder to the front of the flexible scraper 8. Then, the cylinder lifts the heat insulation chamber 7, and the lifting rod 19 raises the substrate 9 to the powder bed position 18. The flexible scraper 8 moves horizontally towards the forming chamber, spreading the titanium alloy powder on top of the substrate 9. After the powder spreading is completed, the cylinder lowers the heat insulation chamber 7, and then the electron beam gun 2 preheats the titanium alloy powder on the substrate 9 at the powder bed position 18.

[0083] During preheating, the titanium alloy powder bed is divided into a forming sintering zone 12, a transition zone 13, and an unsintered zone 14. The forming sintering zone 12 includes the part body and the support area, while the transition zone 13 is the part body outline extending 5-10mm and the support printing area. The preheating is divided into three stages, in the order of unsintered zone 14 → forming sintering zone 12 + transition zone 13 → forming sintering zone 12. The number of preheating scans are 3, 4, and 1, respectively, to increase the temperature of the sintering forming zone and reduce the preheating time. The preheating time of a single layer is ≤40s, and the temperature change of the 18 titanium alloy powder preheating filling sintering cycle at each powder bed position is ≤15℃. The specific parameters for preheating the titanium alloy powder are as follows: accelerating voltage 60KV, electron beam spot diameter 1mm, scanning spacing 1mm; the first preheating scan speed in the first and second preheating stages is 25m / s, beam current 35mA; the second preheating scan speed is 30m / s, beam current 45mA; the third preheating scan speed is 50m / s, beam current 90mA; the fourth preheating scan speed in the second preheating stage is 50m / s, beam current 90mA; and the first preheating scan speed in the third preheating stage is 50m / s, beam current 90mA.

[0084] After the titanium alloy powder is preheated, the titanium alloy powder bed is scanned, filled, and sintered using a focused electron beam. The specific parameters are: accelerating voltage 60KV, electron beam spot diameter 0.2~0.3mm, scanning spacing 0.1mm, layer thickness 0.1mm, checkerboard pattern, partition width 30mm, partition overlap +0.1mm, scanning mode zigzag, beam current 7~20mA, scanning speed in non-overlapping areas 1.5~3m / s, scanning speed in overlapping areas increased to 3~6m / s, and the scanning direction is rotated 90° after each layer is scanned.

[0085] Repeat the above steps to complete the printing of Ti60 high-temperature titanium alloy parts. After forming, inert gas is introduced into the equipment for cooling. Once the temperature drops below 50°C, residual titanium alloy powder and supports are removed from the part. Then, a double annealing heat treatment is performed to optimize the microstructure and mechanical properties. Finally, grinding and polishing are used to obtain the final part. Using this method, the internal defect density of the high-temperature titanium alloy is ≤0.5%.

[0086] Metallographic images such as Figure 3 As shown, the forming accuracy of the part can reach 0.1mm / 100mm. The room temperature tensile strength of the part is ≥1100MPa, and the elongation is ≥10%; the 600℃ tensile strength is ≥650MPa, and the elongation is ≥12%.

Claims

1. An electron beam selective melting and forming equipment, characterized in that: It includes a vacuum chamber (1), an electron beam gun (2), a powder feeding system (3), and a forming cylinder (4); the electron beam gun (2) is fixedly mounted above the vacuum chamber (1) by an alloy support (5), and the electron beam gun (2) and the vacuum chamber (1) are kept sealed. A cylinder (6) is provided on the top of the vacuum chamber (1), and the cylinder (6) is connected to the heat insulation chamber (7). The powder feeding system (3) is provided on both sides of the heat insulation chamber (7), and a flexible scraper (8) made of nickel-iron alloy sheet is provided below the powder feeding system (3). The forming cylinder (4) is composed of a substrate (9) and a heat insulation layer (10).

2. The electron beam selective melting and forming equipment according to claim 1, characterized in that: The electron beam gun (2) and the vacuum chamber (1) are sealed together by a bellows (11).

3. The electron beam selective melting and forming equipment according to claim 2, characterized in that: The alloy support (5) has an expansion coefficient of 3.5~5.0×10⁻⁶. -6 Iron-nickel alloy support at / ℃.

4. The electron beam selective melting and forming equipment according to claim 3, characterized in that: The heat insulation chamber (7) is a heat insulation chamber (7) composed of stainless steel or molybdenum alloy thin plates.

5. The electron beam selective melting and forming equipment according to claim 4, characterized in that: The powder feeding system (3) includes a powder box (15), a rotating shaft (16) and a flexible scraper (8); the rotating shaft (16) is located at the bottom of the powder box (15), and a powder trough is embedded in the rotating shaft (16). By rotating the rotating shaft (16), the titanium alloy powder in the powder box (15) falls in front of the flexible scraper (8).

6. The electron beam selective melting and forming equipment according to claim 5, characterized in that: The flexible scraper (8) is equipped with a horizontal moving device, which controls the horizontal movement of the flexible scraper (8).

7. The electron beam selective melting and forming equipment according to claim 6, characterized in that: The flexible scraper (8) is coated with diamond or tungsten carbide.

8. An electron beam selective melting forming apparatus according to any one of claims 1, 2, or 4, characterized in that: The heat insulation layer (10) includes an iron-nickel alloy layer, a heat insulation material layer and a water-cooling layer, wherein the heat insulation material layer is composed of glass fiber, asbestos and alumina ceramic.

9. The electron beam selective melting and forming equipment according to claim 1, characterized in that: The base plate (9) is mounted on the lifting rod (19), and the base plate (9) is raised and lowered by the lifting rod (19).

10. A method for selective electron beam melting and forming, characterized in that: The electron beam selective melting and forming equipment as described in claim 1 includes the following specific steps: Step s1: Vacuum the vacuum chamber (1) and lower the heat insulation chamber (7); Step s2: Preheat and keep the substrate (9) warm using an electron beam gun (2); Step s3: After the heat preservation is completed, the powder feeding system (3) sends the titanium alloy powder to the front of the flexible scraper (8), raises the substrate (9) to the powder bed position (18), and lifts the heat insulation chamber (7). Step s4: The flexible scraper (8) moves horizontally to the powder bed position (18) to lay titanium alloy powder on the substrate (9); Step s5: Lower the heat insulation chamber (7) and preheat the titanium alloy powder with the electron beam gun (2); Step s6: After preheating, the titanium alloy powder is scanned, filled and sintered using an electron beam gun (2); Step s7: Repeat steps s3, s4, s5 and s6 to complete the printing of the titanium alloy part; Step s8: Inert gas is introduced into the vacuum chamber (1) to cool it down and remove residual titanium alloy powder and supports from the titanium alloy parts; Step s9: Heat treat the titanium alloy parts and grind and polish them to obtain the titanium alloy parts.

11. The electron beam selective melting forming method according to claim 10, characterized in that: In step s1, the vacuum level of the vacuum chamber (1) is evacuated to 10. -3 Below Pa.

12. The electron beam selective melting forming method according to any one of claims 10 or 11, characterized in that: In step s2, the substrate (9) is preheated to 700~1200℃ and kept at that temperature for 30~60 minutes.

13. The electron beam selective melting forming method according to claim 12, characterized in that: In step s5, when the titanium alloy powder is preheated, the substrate (9) in the powder bed position (18) is divided into a forming sintering zone (12), a transition zone (13) and an unsintered zone (14), and preheating is carried out in the order of the first stage unsintered zone (14), the second stage forming sintering zone (12) and the transition zone (13), and the third stage forming sintering zone (12).

14. The electron beam selective melting forming method according to claim 13, characterized in that: When the titanium alloy powder is preheated, the electron beam gun (2) scans the unsintered area (14) of the first stage 3 times, the shaped sintered area (12) and the transition area (13) of the second stage 4 times, and the shaped sintered area (12) of the third stage 1 time.

15. The electron beam selective melting forming method according to claim 14, characterized in that: In step s8, the vacuum chamber (1) is cooled to below 50°C.

Images