A deep blind hole, large bottom, thick shell component and its preparation method

Abstract

This invention provides a deep blind hole, large-bottom, thick-shell component and its preparation method. The upper structure has a first segment with a diameter of D1 and a second segment with a diameter of D2, and the lower structure has a third segment with a diameter of D3 and a tip with a diameter of D4, where D1=D2+(5~20)mm, D2=D3*(1.2~2)mm, and D3=D4*(1.1~3)mm. The preparation method includes the following steps: forming the upper structure of the blind hole and the solid lower structure using an open inner extrusion molding die to obtain a semi-formed part; extruding the first segment of the obtained semi-formed part to the designed length using a secondary extrusion process to obtain the final formed part, and cutting off the excess at the end of the final formed part. The deep blind hole, large bottom, thick shell component obtained by the present invention has an elongation of ≥12%, a surface hardness of HRC53-HRC57, a core hardness of HRC52-HRC55, and a core deformation of ≥20%. The present invention can smoothly and quickly produce deep blind hole, large bottom, thick shell components, and can significantly reduce the end allowance of the blank required for forming.

Description

Technical Field

[0001] This invention relates to the field of deep blind hole shell component technology, specifically to a deep blind hole thick-bottom shell component and its preparation method. Background Technology

[0002] Deep blind hole, thick-bottom shell components refer to shell components with a blind hole depth of not less than 1000 mm and a bottom thickness of not less than 300 mm. These components are typically used as shells for aircraft in the military field. Generally speaking, for ultra-high strength steel deep blind hole, thick-bottom shell components with an outer diameter of 200 mm or more, the surface hardness of the bottom layer is required to be controlled above HRC50, and the core hardness of the bottom layer is required to be controlled above HRC45.

[0003] Currently, one of the traditional manufacturing methods for deep blind hole, large-bottom, thick-shell components is to use a tube and weld the head. However, the strength of the welded area is only about 90% of the strength of the body. It can only meet the usage requirements through reinforced design, and it also requires high technical skills from the welding operators. Another method is to directly process large-diameter solid bars, but this results in a high waste of raw materials per finished product. In particular, it is necessary to leave a 200-300mm allowance at the end, and then cut off a large amount of excess material after forming.

[0004] In addition, some companies use hot stamping technology for forming. This technology enables the finished product to achieve a surface hardness of HRC50-HRC53, a core hardness of HRC45-HRC47, an elongation of approximately 5%, and a core deformation of only about 15-20%, which basically meets the usage requirements. However, this technology still has some areas for optimization, including further improvement in the elongation of deep blind hole, large base, and thick shell components; further optimization in the uniformity of surface and core hardness; further improvement in the deformation of the core area; and further improvement in processing efficiency.

[0005] More importantly, due to the structural characteristics of deep blind hole, large bottom, and thick shell components, it is difficult to control the core hardness of deep blind hole, large bottom, and thick shell components to above HRC50 using traditional hot stamping technology. Summary of the Invention

[0006] This invention provides a deep blind hole, large bottom, thick shell component and its preparation method, aiming to improve at least one of the technical problems raised in the background art from both the structural features and the preparation method of the deep blind hole, large bottom, thick shell component.

[0007] To achieve the above objectives, the present invention adopts the technical solution described below.

[0008] A deep blind hole, thick-bottomed shell component includes an upper structure with a blind hole and a solid lower structure. The upper structure has a first segment with a diameter of D1 and a second segment with a diameter of D2. The lower structure has a third segment with a diameter of D3 and a tip with a diameter of D4. The first segment and the second segment are connected by a first cone structure, the second segment and the third segment are connected by a second cone, and a third cone is provided between the third segment and the tip. Wherein, D1=D2+(5~20)mm, D2=D3*(1.2~2)mm, D3=D4*(1.1~3)mm, the diameter of the blind hole d=(0.5~0.75)*D2, and the thickness of the bottom T=(1~5)*D3.

[0009] As a preferred embodiment, the angle between the conical surface of each cone and the axis of the blind hole is 15° to 60°.

[0010] As a more preferred embodiment, the total length of the shell is 1500~1800mm, the diameter D2 of the second segment is 265~380mm, the total length H1 of the third segment and the third cone is 200mm, the total length H3 of the second segment, the second cone, the third segment and the third cone is 500mm, and the angle between the conical surface of each cone and the axis of the blind hole is 15°~30°.

[0011] In this invention, a method for preparing the aforementioned deep blind hole, large-bottom, thick-shell component includes the following steps:

[0012] Step 1: Use an open inner extrusion molding die to form the upper structure with blind holes and the lower structure with solid holes, to obtain the intermediate molded part (i.e. the molded part in the preparation process, also known as the intermediate molded part).

[0013] Step 2: Use a secondary extrusion process to extrude the first segment of the intermediate molded part to the designed length to obtain the final molded part, and cut off the excess at the end of the final molded part.

[0014] Further: The open internal extrusion die includes a die cavity, a forming punch for engaging the die cavity, and a laterally movable inner die cavity located on the die cavity and below the die cavity. An ejector pin is provided on the inner die cavity. The die cavity and the inner die cavity together form a workpiece cavity with a variable shape. The upper region of the die cavity has a conical truncated cone, the upper diameter of which is larger than the lower diameter. The inner die cavity has a vertically arranged first chamber and a second chamber, both of which can connect to the die cavity. When the first chamber connects to the die cavity, the upper region of the die cavity and the first chamber together form workpiece cavity one. When the second chamber connects to the die cavity, the upper region of the die cavity, the lower region of the die cavity, and the second chamber together form workpiece cavity one. Cavity 2; Two sets of pressure blocks are provided at the top of the die cavity, and the lower end of each set of pressure blocks is hinged to a clamping plate. The two clamping plates are rotatably connected to the mounting parts at the top of the die cavity. A support is provided at the top of the die cavity and below the clamping plates. A conical limiting block is provided in the lower region of the die cavity near the bottom. The conical limiting block has an axial hole that allows the ejector rod to pass through. When the pressure block is pulled upward, the clamping plate rotates clockwise, and the clamping plate rotates to the horizontal position, which is the limit of clockwise rotation. When the clamping plate is in the horizontal position, the distance between the two clamping plates is less than the inner diameter of the die cavity. When the pressure block is moved downward, the clamping plate rotates counterclockwise. The inner die cavity is connected to a hydraulic pushing mechanism, an ejector mechanism, or a screw drive mechanism. The hydraulic pushing mechanism, ejector mechanism, or screw drive mechanism is used to push the inner die cavity laterally to the target position.

[0015] Step 1 specifically includes:

[0016] Step 11: Adjust and fix the position of the inner die cavity so that the first chamber is connected to the die cavity;

[0017] Step 12: Pull the pressure block upward to the appropriate position and fix it so that the distance between the two clamping plates is greater than the outer diameter of the billet;

[0018] Step 13: Feed the blank into the top of the concave mold cavity, control the forming punch to move down until the blank fills the workpiece cavity one under the action of the forming punch, and at this time the preformed part is obtained;

[0019] Step 14: Control the return stroke of the forming punch; control the ejector bar to move upward until the top edge of the preform is above the clamping plate;

[0020] Step 15: Control the pressure block to move upward until the clamping plate rotates counterclockwise to a horizontal state, and then control the top rod to reset. At this time, the protruding edge at the top of the preform is suspended on the clamping plate.

[0021] Step 16: readjust and fix the position of the inner die cavity to connect the second chamber with the die cavity.

[0022] Step 17: Repeat step 12 to allow the preform to fall into the concave mold cavity;

[0023] Step 18: Control the extrusion punch to move downwards until the blank fills the workpiece cavity 2 under the action of the extrusion punch, at which point the intermediate formed part is obtained.

[0024] As a more preferred embodiment, in step 1, the speed of the forming punch during the downward movement is controlled at 10-15 mm / s, and the speed of the extrusion punch during the downward movement is controlled at 20-30 mm / s; step 2 specifically involves controlling the extrusion punch to slowly move downward at a speed of 5 mm / s until the first segment of the resulting intermediate molded part is extruded to the designed length to obtain the final molded part; then controlling the ejector bar to move upward and remove the final molded part, and finally cutting off the excess at the end of the final molded part.

[0025] Beneficial effects: The deep blind hole, large bottom, thick shell component obtained by the scheme of the present invention has an elongation of ≥12%, a surface hardness of HRC53-HRC57, a core hardness of HRC52-HRC55, and a core deformation of ≥20%. The scheme of the present invention has high processing efficiency, can smoothly and quickly prepare deep blind hole, large bottom, thick shell components, and can significantly reduce the end allowance of the blank required for forming. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the deep blind hole, large bottom, and thick shell component structure in the embodiment;

[0027] Figure 2 This is a schematic diagram of the blank filling the workpiece cavity in step 13 of the embodiment;

[0028] Figure 3 This is a schematic diagram of the upward movement of the top rod in step 14 of the embodiment;

[0029] Figure 4 This is a schematic diagram of the top flange of the preform suspended on the clamping plate in step 15 of the embodiment.

[0030] Figure 5 This is a schematic diagram of the preform falling into the concave mold cavity in step 17 of the embodiment;

[0031] Figure 6 This is a schematic diagram of the extrusion process using an extrusion punch in step 18 of the embodiment;

[0032] Figure 7 This is a schematic diagram of the deep blind hole, large bottom, thick shell component obtained in the embodiment. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following description of the embodiments is only for the purpose of helping to understand the principles and core ideas of the present invention, and is not intended to limit the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements made to the present invention without departing from the principles of the present invention also fall within the scope of protection of the claims of the present invention.

[0034] First, the deep blind hole, large bottom, thick shell component to be prepared in the embodiments will be described, such as... Figure 1 As shown, a deep blind hole, large-bottom, thick-shell component includes an upper structure with a blind hole 21 and a solid lower structure. The upper structure has a first segment 22 with a diameter of D1 and a second segment 23 with a diameter of D2. The lower structure has a third segment 24 with a diameter of D3 and a tip with a diameter of D4. The first segment 22 and the second segment 23 are connected by a first conical structure 25, and the second segment 23 and the third segment 24 are connected by a second conical structure 26. A third conical structure 27 is provided between the third segment 24 and the tip. Wherein, D1=D2+(5~20)mm, D2=D3*(1.2~2)mm, D3=D4*(1.1~3)mm, the diameter of the blind hole 21 is d=0.5~0.75*D2, and the thickness of the bottom is T=(1~5)*D3. The angle between the conical surface of each conical structure and the axis of the blind hole 21 is 15°~60°.

[0035] Next, the open internal extrusion die in the embodiment will be described. For example... Figure 2 and Figure 6 As shown, an open internal extrusion molding die includes a die 5, a forming punch 2 for engaging with a die cavity 10, and an extrusion punch 9 for extrusion. A through hole is provided laterally on the die 5, which is used to engage with an inner die 7. The area above the through hole is the upper area of ​​the die cavity 10, and the area below the through hole is the lower area of ​​the die cavity 10. An inner die 7, which can move laterally, is provided on the die 5 and located at the lower part of the die cavity 10 (i.e., the inner die 7 is clearance-fitted into the through hole, with the clearance controlled at 3-5mm). An ejector rod 8 is provided on the inner die 7, arranged vertically. The die cavity 10 and the cavity of the inner die 7 together form a workpiece cavity with a variable shape. The upper region of the die cavity 10 has a conical truncated platform 15, the upper diameter of which is larger than the lower diameter. The inner die 7 has a vertically arranged first chamber 11 and a second chamber 12, both of which can connect to the die cavity 10. The first chamber 11 has a trapezoidal cross-section, and the second chamber 12 has a combination of trapezoidal and rectangular cross-sections. When the first chamber 11 connects to the die cavity 10, the upper region of the die cavity 10 and the first chamber 11 together form workpiece cavity one. Figure 2In the process, the chamber located directly above the ejector rod 8 is the first workpiece cavity; when the second chamber 12 is connected to the concave mold cavity 10, the upper region of the concave mold cavity 10, the lower region of the concave mold cavity 10, and the second chamber 12 together constitute the second workpiece cavity. Figure 5 In the middle, the cavity located directly below the extrusion punch 9 is the workpiece cavity two.

[0036] In this embodiment, a conical limiting block 17 is provided in the lower region of the concave mold cavity 10 near the bottom. The conical limiting block 17 has an axial hole that allows the top material rod 8 to pass through. The conical surface of the conical limiting block 17 matches the conical surface of the lower region of the concave mold cavity 10.

[0037] In this embodiment, two sets of pressure blocks 1 are provided on the top of the die 5. The lower end of each set of pressure blocks 1 is hinged to a clamping plate 3. The two clamping plates 3 are rotatably connected to the mounting parts on the top of the die 5. A support member 4 is provided on the top of the die 5 and below the clamping plates 3. When the pressure block 1 is pulled upward, the clamping plate 3 rotates clockwise. When the clamping plate 3 rotates to a horizontal state, it is the limit position of the clockwise rotation of the clamping plate 3. When it is in a horizontal state, the distance between the two clamping plates 3 is less than the inner diameter of the die cavity 10. When the pressure block 1 is moved downward / pressed, the clamping plate 3 rotates counterclockwise. When the clamping plate 3 rotates counterclockwise to the point where the lower end face of the clamping plate 3 forms an angle of not less than 40° with the horizontal plane, the blank 6, the forming punch 2, and the extrusion punch 9 can pass through the two clamping plates 3 without obstruction.

[0038] In this embodiment, the lead screw of the lead screw drive mechanism is arranged horizontally and located on the side of the inner die 7. The lead screw of the lead screw drive mechanism is perpendicular to the axis of the die cavity 10 but does not intersect it. The inner die 7 is connected to the nut seat of the lead screw drive mechanism. When the lead screw drive mechanism is running, the nut seat can reciprocate along the axial direction of the lead screw. The horizontal movement of the nut seat brings the inner die 7 to the target position. The drive motor of the lead screw drive mechanism is a servo motor.

[0039] Example 1

[0040] In this embodiment, the deep blind hole thick shell component (made of D6AC) has a total shell length H of 1500mm, a diameter D2 of the second segment 23 of 265mm, a total length H1 of the third segment 24 and the third cone 27 of 200mm, a total length H3 of the second segment 23, the second cone 26, the third segment 24 and the third cone 27 of 500mm, and an angle of 15° between the cone surface of each cone and the axis of the blind hole 21. Among them, the diameter D1 of the first segment 22 is 270mm, the diameter D3 of the third segment 24 is 305mm, the tip diameter D4 is 120mm, the angle a between the cone surface of the cone and the axis of the blind hole 21 is 15°, the diameter d of the blind hole 21 is 200mm, the depth h of the blind hole 21 is 1150mm, and the bottom thickness Hh is 350mm.

[0041] A method for preparing the deep blind hole, large bottom, thick shell component of this embodiment using the aforementioned open inner extrusion die includes the following steps:

[0042] Step 1: Use an open inner extrusion die to form the upper structure of the blind hole 21 and the solid lower structure to obtain the intermediate molded part. Specifically,

[0043] Step 11: Adjust and fix the position of the inner cavity 7 so that the first chamber 11 is connected to the cavity 10.

[0044] Step 12: Pull the pressure block 1 upward to the appropriate position and fix it so that the distance between the two clamping plates 3 is greater than the outer diameter of the blank 6;

[0045] Step 13: Feed the blank 6 into the top of the concave mold cavity 10, and control the pressing punch 2 to move downward. The speed of the pressing punch 2 during the downward movement is controlled at 12mm / s until the blank fills the workpiece cavity under the action of the pressing punch 2 (the state at this time is as follows). Figure 2 As shown), at this point, preform 13 is obtained;

[0046] Step 14, control the return stroke of the forming punch 2; as follows Figure 3 As shown, the control rod 8 moves upward until the protrusion 16 at the top of the preform 13 is above the clamping plate 3;

[0047] Step 15: Control the pressure block 1 to move upwards until the clamping plate 3 rotates clockwise to a horizontal position, then control the top rod 8 to reset. At this time, the protruding edge 16 at the top of the preform 13 is suspended on the clamping plate 3. Figure 4 As shown;

[0048] Step 16: readjust and fix the position of the inner cavity 7 so that the second chamber 12 is connected to the cavity 10.

[0049] Step 17, repeat step 2. At this time, the preform will fall into the concave mold cavity 10, as shown. Figure 5 As shown;

[0050] Step 18: Control the extrusion punch 9 to move downwards. The speed of the extrusion punch 9 during the downward movement is controlled at 28 mm / s until the billet fills the workpiece cavity under the action of the extrusion punch 9. At this time, the intermediate formed part 14 is obtained. Figure 6 As shown;

[0051] Step 2: The first segment 22 of the resulting intermediate-formed part is extruded to the designed length using a secondary extrusion process to obtain the final formed part. The excess material at the end of the final formed part is then cut off. Specifically,

[0052] After step 18 is completed, control the extrusion punch 9 to slowly move downward at a speed of 5 mm / s until the first segment 22 of the resulting intermediate molded part is extruded to the designed length to obtain the final molded part; then control the ejector bar 8 to move upward and remove the final molded part, and finally cut off the excess at the end of the final molded part.

[0053] The surface hardness of the deep blind hole, large bottom, and thick shell component obtained in this embodiment reaches HRC53-HRC57, the core hardness reaches HRC52-HRC55, the elongation is 13.7%, the deformation in the core area reaches 37%, and the subsequent machining process takes 200 hours.

[0054] Example 2

[0055] In this embodiment, the deep blind hole thick shell component (made of 30CrMnSiNi2A) has a total shell length H of 1800mm, a diameter D2 of the second segment 23 of 280mm, a total length H1 of the third segment 24 and the third cone 27 of 200mm, a total length H3 of the second segment 23, the second cone 26, the third segment 24 and the third cone 27 of 500mm, and an angle of 30° between the cone surface of each cone and the axis of the blind hole 21. Among them, the diameter D1 of the first segment 22 is 405mm, the diameter D3 of the third segment 24 is 320mm, the tip diameter D4 is 120mm, the angle a of the cone surface of the cone and the axis of the blind hole 21 is 30°, the diameter d of the blind hole 21 is 200mm, the depth h of the blind hole 21 is 1400mm, and the bottom thickness Hh is 400mm.

[0056] A method for preparing the deep blind hole, large bottom, thick shell component of this embodiment using the aforementioned open inner extrusion die includes the following steps:

[0057] Step 1: Use an open inner extrusion die to form the upper structure of the blind hole 21 and the solid lower structure to obtain the intermediate molded part. Specifically,

[0058] Step 11: Adjust and fix the position of the inner cavity 7 so that the first chamber 11 is connected to the cavity 10.

[0059] Step 12: Pull the pressure block 1 upward to the appropriate position and fix it so that the distance between the two clamping plates 3 is greater than the outer diameter of the blank 6;

[0060] Step 13: Feed the blank 6 into the top of the concave mold cavity 10, and control the pressing punch 2 to move downward. The speed of the pressing punch 2 during the downward movement is controlled at 10 mm / s until the blank fills the workpiece cavity under the action of the pressing punch 2 (the state at this time is as follows). Figure 2 As shown), at this point, preform 13 is obtained;

[0061] Step 14, control the return stroke of the forming punch 2; as follows Figure 3As shown, the control rod 8 moves upward until the protrusion 16 at the top of the preform 13 is above the clamping plate 3;

[0062] Step 15: Control the pressure block 1 to move upwards until the clamping plate 3 rotates clockwise to a horizontal position, then control the top rod 8 to reset. At this time, the protruding edge 16 at the top of the preform 13 is suspended on the clamping plate 3. Figure 4 As shown;

[0063] Step 16: readjust and fix the position of the inner cavity 7 so that the second chamber 12 is connected to the cavity 10.

[0064] Step 17, repeat step 2. At this time, the preform will fall into the concave mold cavity 10, as shown. Figure 5 As shown;

[0065] Step 18: Control the extrusion punch 9 to move downwards. The speed of the extrusion punch 9 during the downward movement is controlled at 20 mm / s until the billet fills the workpiece cavity under the action of the extrusion punch 9. At this time, the intermediate formed part 14 is obtained. Figure 6 As shown;

[0066] Step 2: The first segment 22 of the resulting intermediate-formed part is extruded to the designed length using a secondary extrusion process to obtain the final formed part. The excess material at the end of the final formed part is then cut off. Specifically,

[0067] After step 18 is completed, control the extrusion punch 9 to slowly move downward at a speed of 6 mm / s until the first segment 22 of the resulting intermediate molded part is extruded to the designed length to obtain the final molded part; then control the ejector bar 8 to move upward and remove the final molded part, and finally cut off the excess at the end of the final molded part.

[0068] The surface hardness of the deep blind hole, large bottom, and thick shell component obtained in this embodiment reaches HRC54-HRC55, the core hardness reaches HRC51-HRC53, the elongation is 12.5%, the deformation of the core area reaches 30%, and the entire processing cycle is reduced from the original 200 hours.

[0069] Comparative Example 1: The same deep blind hole, large-bottom, thick-shell component as in Example 1 was formed using hot stamping technology, employing a heating-reverse extrusion method. The resulting deep blind hole, large-bottom, thick-shell component achieved a surface hardness of HRC51-HRC53, a core hardness of HRC46-HRC48, an elongation of 5.5%, and a core deformation of only 11%. The entire processing cycle took 280 hours.

[0070] Comparative Example 2: The same deep blind hole, large-bottom, thick shell component as in Example 2 was formed using traditional hot stamping technology, followed by heating and reverse extrusion. The resulting deep blind hole, large-bottom, thick shell component achieved a surface hardness of HRC50-HRC53, a core hardness of HRC45-HRC47, an elongation of 6.2%, and a core deformation of only 13.5%. The entire processing cycle took 300 hours.

[0071] In each embodiment, the core hardness testing sites A (A1, A2, A3), the core region deformation testing site B (the area between A2 and A3 in the figure), and the surface hardness testing sites C1, C2, C3 are shown in the figure. Figure 7 The test results are averaged at the positions shown.

[0072] The deep blind hole, large bottom, thick shell component obtained by the present invention has an elongation of ≥12%, a surface hardness of HRC52-HRC57, a core hardness of HRC51-HRC55, and a core deformation of ≥30%. The present invention has high processing efficiency, can smoothly and quickly produce deep blind hole, large bottom, thick shell components, and can significantly reduce the end allowance of the blank required for forming. The resulting formed part only needs to have less than 50 mm of end allowance cut off from the upper and lower ends.

Claims

1. A deep blind hole, large-bottom, thick-shell component, comprising an upper structure with a blind hole (21) and a solid lower structure, characterized in that: The upper structure has a first segment (22) with a diameter of D1 and a second segment (23) with a diameter of D2. The lower structure has a third segment (24) with a diameter of D3 and a tip with a diameter of D4. The first segment (22) and the second segment (23) are connected by a first conical structure (25). The second segment (23) and the third segment (24) are connected by a second cone (26). There is a third cone (27) between the third segment (24) and the tip. Wherein, D1 = D2 + (5~20) mm, D2 = D3 * (1.2~2) mm. mm, D3=D4*(1.1~3)mm, the diameter of the blind hole (21) d=(0.5~0.75)*D2, the thickness of the bottom T=(1~5)*D3; the angle between the cone surface of each cone and the axis of the blind hole (21) is 15°~60°; the total length of the shell is 1500~1800mm, the diameter D2 of the second segment (23) is 265~380mm, the total length H1 of the third segment (24) and the third cone (27) is 200mm, the total length H3 of the second segment (23), the second cone (26), the third segment (24) and the third cone (27) is 500mm, and the angle between the cone surface of each cone and the axis of the blind hole (21) is 15°~30°.

2. A method for preparing a deep blind hole, large-bottom, thick-shell component as described in claim 1, characterized in that the steps are as follows: include: Step 1: The upper structure of the blind hole (21) and the lower structure of the solid part are formed by using an open inner extrusion molding die to obtain the middle molded part; Step 2: The first segment (22) of the obtained intermediate molded part is extruded to the designed length using a secondary extrusion process to obtain the final molded part, and the excess at the end of the final molded part is cut off.

3. The preparation method according to claim 2, characterized in that: The open internal extrusion die includes a die cavity (5), a forming punch (2) for cooperating with the die cavity (10), and an inner die cavity (7) that can move laterally on the die cavity (5) and located at the lower part of the die cavity (10). An ejector rod (8) is provided on the inner die cavity (7). The die cavity (10) and the cavity of the inner die cavity (7) together form a workpiece cavity with a variable shape. The upper region of the die cavity (10) has a truncated cone (15), and the upper diameter of the truncated cone (15) is larger than that of the lower diameter of the truncated cone (15). Diameter; wherein, the inner die (7) has a first chamber (11) and a second chamber (12) arranged vertically, and both the first chamber (11) and the second chamber (12) can be connected to the die cavity (10); when the first chamber (11) is connected to the die cavity (10), the upper region of the die cavity (10) and the first chamber (11) together constitute the workpiece cavity; when the second chamber (12) is connected to the die cavity (10), the upper region of the die cavity (10) and the lower region of the die cavity (10) together constitute the workpiece cavity. The area and the second chamber (12) together constitute the workpiece cavity two; two sets of pressure blocks (1) are provided on the top of the die (5), and the lower end of each set of pressure blocks (1) is hinged to the clamping plate (3). The two clamping plates (3) are rotatably connected to the mounting parts on the top of the die (5). A support (4) is provided on the top of the die (5) and below the clamping plate (3); a conical limiting block (17) is provided in the lower area of ​​the die cavity (10) near the bottom. An axially arranged conical limiting block (17) allows the ejector rod (8) to pass through. The hole; when the pressure block (1) is pulled upward, the clamping plate (3) rotates clockwise, and the clamping plate (3) rotates to the horizontal state, which is the limit position of clockwise rotation. When the clamping plate (3) is in the horizontal state, the distance between the two clamping plates (3) is less than the inner diameter of the concave mold cavity (10); when the pressure block (1) is moved downward, the clamping plate (3) rotates counterclockwise; the inner concave mold (7) is connected to a hydraulic pushing mechanism, a pressing mechanism or a screw transmission mechanism. The hydraulic pushing mechanism, the pressing mechanism or the screw transmission mechanism is used to push the inner concave mold (7) laterally to the target position. Step 1 specifically includes: Step 11: Adjust and fix the position of the inner cavity mold (7) so that the first chamber (11) is connected to the cavity mold cavity (10); Step 12: Pull the pressure block (1) upward to the appropriate position and fix it so that the distance between the two clamping plates (3) is greater than the outer diameter of the blank; Step 13: Feed the blank into the top of the concave mold cavity (10), control the pressing punch (2) to move down until the blank fills the workpiece cavity under the action of the pressing punch (2), and at this time the preform (13) is obtained. Step 14: Control the return stroke of the forming punch (2); control the ejector bar (8) to move upward until the top flange (16) of the preform (13) is above the clamping plate (3); Step 15: Control the pressure block (1) to move upward until the clamping plate (3) rotates counterclockwise to a horizontal state, and then control the top rod (8) to reset. At this time, the protruding edge (16) on the top of the preform (13) is suspended on the clamping plate (3). Step 16: readjust and fix the position of the inner cavity mold (7) so that the second chamber (12) is connected to the cavity mold cavity (10); Step 17, repeat step 12; Step 18: Control the extrusion punch (9) to move down until the blank fills the workpiece cavity under the action of the extrusion punch (9), and at this time the medium-formed part is obtained.

4. The preparation method according to claim 3, characterized in that: In step 1, the speed of the forming punch (2) during the downward movement is controlled at 10-15 mm / s, and the speed of the extrusion punch (9) during the downward movement is controlled at 20-30 mm / s; Step 2 is as follows: control the extrusion punch (9) to move slowly downward at a speed of 5 mm / s until the first segment (22) of the resulting intermediate molded part is extruded to the designed length to obtain the final molded part; then control the ejector bar (8) to move upward and take out the final molded part, and finally cut off the excess at the end of the final molded part.

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