Open inner type extrusion forming die and large-size blind hole shell forming process

Abstract

This invention provides an open-type internal extrusion forming die and a forming process for large-size blind hole shells, including a die cavity, a forming punch, and an extrusion punch. A laterally movable inner die is provided on the die cavity, and an ejector rod is provided on the inner die. The die cavity and the inner die cavity together form a workpiece cavity with a variable shape. The inner die has a vertically arranged first chamber and a second chamber, both of which can connect with the die cavity. The process steps include: pulling the pressure block upwards so that the distance between the two clamping plates is greater than the outer diameter of the blank; feeding the blank from the top of the die cavity; controlling the forming punch to move downwards until the blank fills the workpiece cavity under the action of the forming punch; controlling the forming punch to return; controlling the ejector rod to move upwards until the top flange of the preform is above the clamping plates. This invention can not only smoothly and quickly produce large-size blind hole shells, but also significantly reduce the end allowance of the blank required during the forming process.

Description

Technical Field

[0001] This invention relates to the field of projectile forming technology, specifically to an open-type internal extrusion forming die and a forming process for large-size blind hole shells. The large-size blind hole shells described in this invention refer to formed parts with an internal length-to-diameter ratio of not less than 5 and an external length-to-diameter ratio of not less than 6. Background Technology

[0002] In projectile hot stamping forming technology, a forming process is typically used to obtain blind hole components by extrusion forming under the action of a fixed concave mold cavity. Due to the slender extrusion punch used, the extrusion punch is prone to instability under vertical pressure, resulting in the blind hole shell obtained by the fixed concave mold cavity typically having an inner length-to-diameter ratio of no more than 3 and an outer length-to-diameter ratio of no more than 4.5.

[0003] More importantly, when using existing processes to mold large-sized blind hole shells, a 200-300mm allowance must be left at the end, and a large amount of excess material must be cut off after molding. Obviously, this is a huge waste of molding material. Summary of the Invention

[0004] The purpose of this invention is to provide an open internal extrusion molding die and a large-size blind hole shell molding process, which can at least significantly reduce the end allowance of the blank required during the molding process.

[0005] To achieve the above objectives, the present invention adopts the technical solution described below.

[0006] An open internal extrusion forming die includes a die cavity, a forming punch for engaging the die cavity, and an extrusion punch. A laterally movable inner die is located on the die cavity and below the die cavity, and an ejector pin is provided on the inner die. 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 has a vertically arranged first chamber and a second chamber, both of which can connect with the die cavity.

[0007] When the first chamber is connected to the concave mold cavity, the upper region of the concave mold cavity and the first chamber together constitute workpiece cavity one; when the second chamber is connected to the concave mold cavity, the upper region of the concave mold cavity, the lower region of the concave mold cavity and the second chamber together constitute workpiece cavity two.

[0008] Furthermore, at least two sets of pressure blocks are provided at the top of the die cavity. Each set of pressure blocks is hinged to a clamping plate at its lower end. The two clamping plates are rotatably connected to a mounting component at the top of the die cavity. A support component is provided at the top of the die cavity, below the clamping plates. When the pressure blocks are pulled upwards, the clamping plates rotate clockwise, with the horizontal position representing the limit of clockwise rotation. When the clamping plates are horizontal, the distance between them is less than the inner diameter of the die cavity. When the pressure blocks are moved downwards, the clamping plates rotate counterclockwise. This structure significantly improves the molding efficiency of large-sized blind hole shells.

[0009] Furthermore, the inner die is connected to a hydraulic pushing mechanism, a pressing mechanism, or a screw drive mechanism, which is used to push the inner die laterally to the target position.

[0010] As a preferred embodiment, the inner die is connected to the nut seat of the lead screw drive mechanism. The horizontal movement of the nut seat brings the inner die to the target position. The drive motor of the lead screw drive mechanism is a servo motor. This design facilitates smooth workpiece forming and prevents jamming during the extrusion process.

[0011] A process for forming a large-size blind hole shell using the aforementioned open inner extrusion die includes the following steps:

[0012] Step 1: Adjust and fix the position of the inner die cavity to connect the first chamber with the die cavity.

[0013] Step 2: Press the pressure block down 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;

[0014] Step 3: 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;

[0015] Step 4: Control the return stroke of the forming punch; control the ejector bar to move upward until the top flange of the preform is above the clamping plate;

[0016] Step 5: 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 protrusion at the top of the preform is suspended on the clamping plate.

[0017] Step 6: readjust and fix the position of the inner die cavity to connect the second chamber with the die cavity.

[0018] Step 7: Repeat step 2. At this time, the preform falls into the concave mold cavity.

[0019] Step 8: Control the extrusion punch to move downwards until the billet fills the workpiece cavity two under the action of the extrusion punch, at which point the final formed part is obtained;

[0020] Step 9: First, control the top rod to move upward, then take out the final molded part, and finally cut off the excess at the bottom of the final molded part.

[0021] As a preferred option, the upper diameter of the conical platform is 5-20 mm larger than the lower diameter of the conical platform.

[0022] As a preferred embodiment, the upper diameter of the conical platform is 420 mm, the lower diameter of the conical platform is 400 mm, and the distance between the two clamping plates when in a horizontal state is 398 mm; the total length of the concave mold cavity is 2800 mm, the length of the upper region of the concave mold cavity is 2400 mm, and the diameter of the upper region of the concave mold cavity is greater than the diameter of the lower region of the concave mold cavity.

[0023] As a preferred option, the speed of the forming punch during the downward movement is controlled at 5-20 mm / s, and the speed of the extrusion punch during the downward movement is controlled at 20-40 mm / s.

[0024] Beneficial effects: The solution of this invention can not only smoothly and quickly produce large-sized blind hole shells with an inner diameter ratio of not less than 5 and an outer diameter ratio of not less than 6, but also significantly reduce the end allowance of the blank required during the forming process. For the forming of large-sized blind hole shells, only 15-50mm of the end allowance of the formed part needs to be cut off; it can also prevent jamming during the extrusion process. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the blank being fed into the top of the concave mold cavity in the embodiment;

[0026] Figure 2 This is a schematic diagram of the blank filling the workpiece cavity at one point in the embodiment;

[0027] Figure 3 This is a schematic diagram of the upward movement of the top rod in the embodiment;

[0028] Figure 4 This is a schematic diagram of the top flange of the preform suspended on the clamping plate in the embodiment;

[0029] Figure 5 This is a schematic diagram of the preform falling into the concave mold cavity in the embodiment;

[0030] Figure 6 This is a schematic diagram of the extrusion process using an extrusion punch in the embodiment. Detailed Implementation

[0031] 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.

[0032] Example 1

[0033] First, the open internal extrusion die in this embodiment will be described. For example... Figure 1 and Figure 5 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 1 In 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.

[0034] 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 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 member 4 is provided on the top of the die 5 and below the clamping plate 3. When the pressure block 1 is pulled upward, the clamping plate 3 rotates clockwise. When the clamping plate 3 rotates to the horizontal state, it is the limit position of the clockwise rotation of the clamping plate 3. When it is in the 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, 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.

[0035] In this embodiment, the lead screw of the lead screw transmission mechanism is arranged horizontally and located on the side of the inner die 7. The lead screw of the lead screw transmission 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 transmission mechanism. When the lead screw transmission 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 transmission mechanism is a servo motor.

[0036] In this embodiment, the upper diameter of the conical truncated platform 15 (i.e., Figure 1 The diameter of the lower part of the truncated cone 15 (i.e., D1) is 420mm. Figure 1 The diameter of the blank 6 (D2) is 400mm, and the distance between the two clamping plates 3 when in a horizontal state is 398mm; the total length of the concave mold cavity 10 is 2800mm, the length of the upper region of the concave mold cavity 10 is 2400mm, the diameter of the upper region of the concave mold cavity 10 is larger than the diameter of the lower region of the concave mold cavity 10, and the diameter of the blank 6 (i.e. Figure 1 The diameter of the middle section (D) is 410 mm.

[0037] A large-size blind hole shell forming process using the open inner extrusion die in this embodiment involves preparing a large-size blind hole shell with dimensions (total length 2790 mm, total inner cavity length 2385 mm) using 30CrMnSiA alloy feedstock. The steps include:

[0038] Step 1: Adjust and fix the position of the inner cavity 7 so that the first chamber 11 is connected to the cavity 10.

[0039] Step 2: Press down the pressure block 1 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;

[0040] Step 3: Feed the blank 6 into the top of the concave mold cavity 10 (at this time, the blank is in the following state). Figure 1As shown), the forming punch 2 is controlled to move downwards at a speed of 10 mm / s until the blank fills the workpiece cavity under the action of the forming punch 2 (the state at this time is as shown). Figure 2 As shown), at this point, preform 13 is obtained;

[0041] Step 4, control the return stroke of the forming punch 2; such as 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;

[0042] Step 5: Control the pressure block 1 to move upwards until the clamping plate 3 rotates counterclockwise 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, as shown. Figure 4 As shown;

[0043] Step 6: readjust and fix the position of the inner cavity 7 so that the second chamber 12 is connected to the cavity 10.

[0044] Step 7, repeat step 2. This time, the preform falls into the concave mold cavity 10, as shown. Figure 5 As shown;

[0045] Step 8: Control the extrusion punch 9 to move downwards. The speed of the extrusion punch 9 during the downward movement is controlled at 25 mm / s until the billet fills the workpiece cavity under the action of the extrusion punch 9. At this time, the final formed part 14 is obtained. Figure 6 As shown;

[0046] Step 9: First, control the top rod 8 to move upward, then take out the final molded part 14, and finally cut off the excess at the bottom of the final molded part 14 to obtain a large-size blind hole shell product. The required excess to be cut off is (5mm of excess needs to be cut off at the upper end of the final molded part 14 and 10mm of excess needs to be cut off at the lower end).

[0047] The extruded part obtained in this embodiment has a grain size deviation of less than 1 at the head and tail; the overall tensile strength is ≥1500MPa, and the head and tail deviation is less than 75MPa.

[0048] Example 2

[0049] A large-size blind hole shell forming process using an open-internal extrusion die, wherein the open-internal extrusion die is described in Example 1, the main difference being that the upper diameter of the conical platform 15 (i.e. Figure 1 The diameter of the lower part of the truncated cone 15 (i.e., D1) is 450mm. Figure 1The diameter of the blank 6 (D2) is 430mm, and the distance between the two clamping plates 3 when in a horizontal state is 400mm; the total length of the concave mold cavity 10 is 3000mm, the length of the upper region of the concave mold cavity 10 is 2800mm, the diameter of the upper region of the concave mold cavity 10 is larger than the diameter of the lower region of the concave mold cavity 10, and the diameter of the blank 6 (i.e. Figure 1 The diameter of the middle section (D) is 442 mm.

[0050] In this example, a large-sized blind hole shell with dimensions of 2985 mm (total length 2985 mm, total inner cavity length 2654 mm) is prepared using 2A12 aluminum alloy. The steps include:

[0051] Step 1: Adjust and fix the position of the inner cavity 7 so that the first chamber 11 is connected to the cavity 10.

[0052] Step 2: Press down the pressure block 1 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;

[0053] Step 3: Feed the blank 6 into the top of the concave mold cavity 10 (at this time, the blank is in the following state). Figure 1 As shown), the forming punch 2 is controlled to move downwards at a speed of 10 mm / s until the blank fills the workpiece cavity under the action of the forming punch 2 (the state at this time is as shown). Figure 2 As shown), at this point, preform 13 is obtained;

[0054] Step 4, control the return stroke of the forming punch 2; such as 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;

[0055] Step 5: 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 on the top of the preform 13 is suspended on the clamping plate 3. Figure 4 As shown;

[0056] Step 6: readjust and fix the position of the inner cavity 7 so that the second chamber 12 is connected to the cavity 10.

[0057] Step 7, repeat step 2. This time, the preform falls into the concave mold cavity 10, as shown. Figure 5 As shown;

[0058] Step 8: Control the extrusion punch 9 to move downwards. The speed of the extrusion punch 9 during the downward movement is controlled at 40 mm / s until the billet fills the workpiece cavity under the action of the extrusion punch 9. At this time, the final formed part 14 is obtained. Figure 6 As shown;

[0059] Step 9: First, control the top rod 8 to move upward, then remove the final formed part 14, and finally cut off the excess at the bottom of the final formed part 14 to obtain a large-size blind hole shell product. The required excess to be cut off is (6mm at the upper end and 12mm at the lower end of the final formed part 14). The resulting shell (after cutting off the excess in the final formed part 14) has a grain size deviation of less than grade 1 at the head and tail, a tensile strength ≥450MPa, and a tensile head-to-tail difference <50MPa.

[0060] Comparative Example 1

[0061] Using the same fixed concave mold cavity as the final molded part 14 in Example 1, the final molded part 14 is directly produced by extrusion molding. The extrusion speed is controlled as follows (the first extrusion speed is controlled at 15 mm / s, and the second extrusion speed is controlled at 15 mm / s). The upper end of the resulting final molded part 14 needs to be cut off with an allowance of 150 mm, and the lower end needs to be cut off with an allowance of 80 mm. The grain size deviation of the head and tail of the resulting shell is greater than grade 2, and the tensile strength difference is greater than 150 MPa.

[0062] Comparative Example 2

[0063] Using the same fixed concave mold cavity as the final molded part 14 in Example 2, the final molded part 14 is directly produced by extrusion molding. The extrusion speed is controlled as follows (the first extrusion speed is controlled at 25 mm / s, and the second extrusion speed is controlled at 25 mm / s). The resulting final molded part 14 requires a 75 mm allowance to be cut off at the upper end and a 210 mm allowance to be cut off at the lower end. The inner hole centerline is curved, resulting in product defects. The grain size deviation of the head and tail of the obtained shell is greater than grade 3, and the tensile strength difference is greater than 75 MPa.

[0064] Comparative Example 3

[0065] A large-size blind hole shell forming process using an open internal extrusion die, referring to Example 1, differs from Example 1 in that: the inner die 7 is connected to a hydraulic pushing mechanism, which pushes the inner die 7 laterally to the target position. During the forming and extrusion process, when the lower end of the blank 6 just enters the first chamber 11 and the second chamber 12, there is a 2-3 second jamming phenomenon.

[0066] Comparative Example 4

[0067] A large-size blind hole shell forming process of an open inner extrusion molding die, referring to Example 1, the difference from Example 1 is that: the inner die 7 is connected to a pressing mechanism (cylinder driven), the pressing mechanism pushes the inner die 7 laterally to the target position.

[0068] During the molding and extrusion process, when the lower end of the billet 6 just enters the first chamber 11 and the second chamber 12, there is a 4-5 second jamming phenomenon.

[0069] Using the schemes of Examples 1 and 2, large-sized blind hole shells with an inner diameter ratio of not less than 5 and an outer diameter ratio of not less than 6 can be successfully and quickly produced. Moreover, the end allowance of the blank required during the forming process can be significantly reduced. For the forming of large-sized blind hole shells, only a short portion of the end allowance of the blank needs to be cut off. During the pressing and extrusion process, jamming can also be prevented.

Claims

1. A forming process for large-size blind hole shells using an open inner extrusion die, characterized in that, The open internal extrusion die includes a die cavity (5), a forming punch (2) for fitting 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 the lower diameter of the truncated cone (15). The inner die cavity (7) has a first chamber (11) and a second chamber (12) arranged vertically. 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 (12) form a ductile ... 1) Together they form 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 form the second workpiece cavity; at least two sets of pressure blocks (1) are provided on the top of the concave mold (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 concave mold (5). A support (4) is provided on the top of the concave mold (5) and below the clamping plate (3); when the pressure block (1) is pulled upward, the clamping plate (3) rotates clockwise, and when the clamping plate (3) rotates to the horizontal state, it is the limit position of clockwise rotation. When the two clamping plates (3) are in the horizontal state, the distance between them 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 process includes the following steps: Step 1: 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 2: Press the pressure block (1) down 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 billet; Step 3: 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 4: 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 5: 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 6: 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 7, repeat step 2; Step 8: Control the extrusion punch (9) to move down until the blank fills the workpiece cavity 2 under the action of the extrusion punch (9), and at this time the final molded part (14) is obtained. Step 9: First, control the top rod (8) to move upward, then take out the final molded part (14), and finally cut off the excess at the bottom of the final molded part (14).

2. The large-size blind hole shell forming process according to claim 1, characterized in that: The upper diameter of the conical truncated platform (15) is 5-20 mm larger than the lower diameter of the conical truncated platform (15).

3. The large-size blind hole shell forming process according to claim 1, characterized in that: The upper diameter of the conical platform (15) is 420 mm, the lower diameter of the conical platform (15) is 400 mm, and the distance between the two clamping plates (3) when in a horizontal state is 398 mm; the total length of the concave mold cavity (10) is 2800 mm, the upper region length of the concave mold cavity (10) is 2400 mm, and the upper region diameter of the concave mold cavity (10) is greater than the lower region diameter of the concave mold cavity (10).

4. The large-size blind hole shell forming process according to claim 3, characterized in that: The speed of the forming punch (2) during the downward movement is controlled at 5-20 mm / s, and the speed of the extrusion punch (9) during the downward movement is controlled at 20-40 mm / s.

5. The large-size blind hole shell forming process according to claim 1, characterized in that: The inner die (7) is connected to a hydraulic pushing mechanism, a pressing mechanism or a screw drive mechanism. The hydraulic pushing mechanism, pressing mechanism or screw drive mechanism is used to push the inner die (7) laterally to the target position.

6. The large-size blind hole shell forming process according to claim 1, characterized in that: The inner die (7) is connected to the nut seat of the screw drive mechanism. The inner die (7) is brought to the target position by the horizontal movement of the nut seat. The drive motor of the screw drive mechanism is a servo motor.

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