Stamping device and stamping method for stamping part

Abstract

The invention discloses a stamping part stamping device and a stamping method, and relates to the technical field of stamping, the stamping part stamping device comprises a blank holder sliding up and down in the die opening direction, a punch installed on an upper die is arranged in the middle of the blank holder in a sliding mode, a first reset part is arranged between the lower punch and the upper die, and a retainer plate installed on a lower die is arranged below the blank holder; a threaded rod is fixed to the position, below the lower punch, of the lower die, a lower mold core is connected to the threaded rod through a spiral groove, at least three sets of flanging cutter blocks are arranged on the upper end face of the lower mold core, the flanging cutter blocks and the lower mold core are connected in a sliding mode, and second reset pieces are arranged between the flanging cutter blocks and the lower mold core. The stretching process and the flanging process are combined together, one set of die and one station can be shared, so that the overall production cost is effectively reduced, the two processes are carried out in one die, workpieces do not need to be transferred between two stations, and the production time is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of stamping, and specifically to a stamping device and a stamping method for stamped parts. Background Art

[0002] Aluminum alloy precision forging parts are aluminum alloy forgings with complex shapes and high precision forged on forging equipment. Its production process is to bring the workpiece to be forged (such as a sheet) into contact with the mold surface through a hydraulic device, and by means of stamping, to prompt the formation of the required shape on the surface of the workpiece (such as grooves or holes on the surface of the sheet). This process does not require cutting and machining and is widely used in the preparation of aluminum alloy sheet workpieces.

[0003] In the aluminum alloy forming process, generally, two sets of molds are required for the stretching and flanging processes, which are realized successively at two stations. Especially for some parts with a cylindrical stretching with undercuts, two sets of molds mean a significant increase in cost. Firstly, there is an extra set of molds, secondly, an extra press is occupied, and it also takes working hours to transfer the workpiece between the two presses, resulting in low overall efficiency. On the other hand, for relatively thin aluminum alloy parts, the possibility of defects such as breakage and cracks is relatively high during one-time overall flanging. For this reason, we propose a stamping device and a stamping method for stamped parts. Summary of the Invention

[0004] The purpose of the present invention is to provide a stamping device and a stamping method for stamped parts to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A stamping device and a stamping method for stamped parts, including a blank holder that slides up and down along the mold opening direction. There is a first nitrogen spring between the blank holder and the upper mold. A punch installed on the upper mold is slidably arranged at the middle position of the blank holder. The punch is composed of an upper punch and a lower punch. The upper punch and the lower punch are bounded by the middle of the stretching depth. The upper punch is cylindrical and slides with the lower punch, and there is a second nitrogen spring between the upper punch and the upper mold. There is a first resetting member between the lower punch and the upper mold. Below the blank holder, there is a blank holding plate installed on the lower mold. A third nitrogen spring is connected between the blank holding plate and the lower mold. The blank holding plate is divided into two halves centered on the axis of the lower punch. During the downward movement of the blank holding plate along the mold opening direction, the two halves close to form a stretching and flanging cavity. Below the lower punch, a screw is fixed on the lower mold, and a lower core is connected to the screw through a spiral groove. At least three groups of flanging cutter blocks are circumferentially arranged on the upper end surface of the lower core with the axis as the center. The flanging cutter blocks are slidably connected to the lower core. There is a second resetting member between the flanging cutter blocks and the lower core. In the initial state, one end of the flanging cutter block extends beyond the upper end surface of the lower core. When the lower punch touches and slides, it flanges the workpiece. And during the process of the lower punch touching the flanging cutter block, the lower core rotates under the action of the screw, causing the flanging cutter blocks to rotate circumferentially. There is a third resetting member between the lower core and the lower mold.

[0006] Preferably, the working surface of the flanging tool block is a curved surface, and the line contact is formed between the working surface and the workpiece.

[0007] Preferably, a rolling shaft is rotatably installed on the flanging tool block. There are multiple groups of rolling shafts, and the contact points between the rolling shafts and the workpiece form a working surface to generate rolling pressure.

[0008] Preferably, the circumferential surface of the rolling shaft is concave inward toward the axis, and the circular peripheral edge line corresponding to the cross-section passing through the axis is always in two-point contact with the workpiece.

[0009] Preferably, the circumferential surface of the rolling shaft is a spindle shape protruding outward.

[0010] Preferably, a tuning fork-shaped mounting frame is rotatably arranged on the flanging tool block. Both ends of the rolling shaft are rotatably connected to the mounting frame, and when the flanging tool block moves spirally, the inclination angle of the rolling shaft changes with the shape of the workpiece surface.

[0011] Preferably, the rotation angle of the flanging tool block by the screw is at least twice the circumferential angle between adjacent two flanging tool blocks, and when the flanging tool block rotates to the middle of the stroke, the workpiece completes flanging.

[0012] Preferably, the initial contact surface between the flanging tool block and the lower punch is an arc surface.

[0013] Preferably, a stamping method of a stamping part stamping device includes the following steps:

[0014] S1 First stretching, the upper punch and the lower punch move downward synchronously relative to the workpiece for stretching;

[0015] S2 Second stretching, after the upper punch completely contacts the workpiece, the lower punch continues to move downward to complete the stretching of the flanging part;

[0016] S3 Flanging, the flanging includes the following two sub-steps:

[0017] A1 Expanding flanging, the lower punch moves downward and drives the flanging tool block to slide, and during the rotation of the lower core, the flanging tool block expands radially outward and rotates circumferentially to form an overall expansion;

[0018] A2 Shaping, after the expansion is completed, the lower core continues to rotate to drive the flanging tool block to rotate, and then shape the flanging position.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] By combining the two processes of stretching and flanging together, the present invention can share a set of molds and a common working station, thereby effectively reducing the overall production cost, and because the two processes are in one mold and there is no need to transfer the workpiece between two working stations, the production man-hours are saved;

[0021] In the flanging process of the present invention, the rolling method is adopted, which can effectively avoid scratching the surface of the workpiece. Especially for some workpieces with a relatively thin thickness, the rotary rolling method can reduce the possibility of workpiece breakage and crack generation, and improve the qualified product rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall half-sectional structure of the present invention;

[0023] Figure 2 It is a schematic diagram of the half-sectional structure of the lower core;

[0024] Figure 3 is Figure 2 a schematic enlarged view of the structure of area A in

[0025] Figure 4 It is a schematic diagram of the half-sectional structure of the flanging tool block;

[0026] Figure 5 It is a schematic diagram of the flanging process of the working surface of the flanging tool block;

[0027] Figure 6 It is a top view of the trajectory of the flanging tool block;

[0028] Figure 7 It is a schematic diagram of the trajectory of the front view of the flanging tool block;

[0029] Figure 8 It is a schematic diagram of various states of the stretching of the lower punch;

[0030] Figure 9 It is a schematic diagram of an embodiment of the rolling shaft;

[0031] Figure 10 The rolling shaft is different from Figure 9 another embodiment schematic diagram;

[0032] Figure 11 It is a schematic diagram of the structure of the mounting bracket.

[0033] In the figure: 1 - blank holder; 2 - punch; 21 - upper punch; 22 - lower punch; 3 - stock plate; 4 - screw; 5 - lower core; 51 - spiral groove; 52 - chute; 6 - flanging tool block; 61 - limiting strip; 7 - second resetting member; 8 - third resetting member; 9 - rolling shaft; 10 - mounting bracket. DETAILED DESCRIPTION OF THE INVENTION

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0035] Please refer to Figure 1 and Figure 8 , the present invention provides a technical solution: a stamping device for stampings. The upper die mainly includes a blank holder 1, an upper punch 21 and a lower punch 22. The blank holder 1 is used to press the edge of the area where the workpiece needs to be stretched in advance. A first nitrogen spring is arranged between the blank holder 1 and the upper die base. Compared with an ordinary linear spring, the nitrogen spring has a relatively constant initial pressure value and will not be compressed at all before reaching this pressure. The upper punch 21 is a ring-shaped cylinder, and its lower end can extend to a position near half of the depth of the area where the workpiece is stretched. And a second nitrogen spring is arranged between the upper end of the upper punch 21 and the upper die base. The stroke of the first nitrogen spring is greater than that of the second nitrogen spring. The lower punch 22 has a T-shaped cross-section, and a first reset member is arranged between the upper end of the lower punch 22 and the upper die base. The first reset member is preferably a helical spring, and the elastic force of the helical spring will generate a greater reaction force as the stroke of stretching or compressing increases. The lower punch 22 acts to provide the expansion of the lower edge of the workpiece during stretching. As Figure 1 shown, in the state where stretching and flanging are combined, if the punch 2 cannot move down to the lowest end of stretching, the state shown in b2 of 8 will occur, and the lower end of stretching is in a state of converging towards the axis. Only as Figure 8 shown in b3 can complete stretching. And because the flapper needs enough space, after the lower punch 22 moves down to complete stretching, it is necessary to make room for flanging. Therefore, the first reset member is used to move the lower punch 22 up to return to the state of fitting with the upper punch 21;

[0036] Refer to Figure 1 , Figure 2 and Figure 3 , the lower die includes a blank holder plate 3, a screw 4, a lower core 5 and a flanging blade block 6. The blank holder plate 3 is in the form of two semi-open petals. Since side-opening is required for material taking after flanging, the blank holder plate 3 has two actions. One is that during the downward pressing of the blank holder 1, the two petals are combined to form a cavity (and there is also a spring for reset), and the other is to continue to move down to drive the lower core 5. A third nitrogen spring is arranged between the blank holder plate 3 and the lower die base, and the initial force of the third nitrogen spring is greater than the initial force of the first nitrogen spring corresponding to the blank holder 1. Since this kind of structure similar to a wedge in the die is a conventional structure in the die, it will not be described in detail here;

[0037] The lower core 5 is frustum-shaped, and its lower end is slidably arranged in the lower die base along the mold opening direction. A spiral groove 51 is opened at the lower end of the lower core 5, and a screw rod 4 adapted to the spiral groove 51 is fixed on the lower die base correspondingly. A step is also provided in the middle of the lower core 5, and a third reset member 8 is arranged between the step and the lower die base. The third reset member 8 is also preferably a spiral spring. A plurality of sliding grooves 52 are opened at the upper end of the lower core 5. The sliding grooves 52 are used to install the flanging blade blocks 6. The sliding grooves 52 start from the upper end of the lower core 5 and extend radially outward along the axial direction of the lower core 5 during the process of moving downward along the axial direction of the lower core 5. The whole is arc-shaped, and convex blocks are installed on both side walls of the sliding grooves 52 to form a limitable slide rail. Limit strips 61 are arranged on both side walls of the flanging blade block 6, and the limit strips 61 slide in the sliding grooves 52. At least three groups of flanging blade blocks 6 are provided, and they are evenly distributed circumferentially, and preferably four or five groups. If the number of flanging blade blocks 6 is too small, the lower core 5 needs to move down a larger stroke. Semi-circular grooves are opened on the arc-shaped surface of the flanging blade block 6 and in the arc-shaped surface of the sliding groove 52, and the two form a complete arc-shaped cylindrical groove. The second reset member 7 is arranged in the cylindrical groove. The second reset member 7 is also preferably a spiral spring, and its two ends are respectively fixed to the flanging blade block 6 and the sliding groove 52;

[0038] As Figure 2 shown, a flange can also be provided on the outer edge of the lower core 5, and a nitrogen spring can be provided through the flange;

[0039] Refer to Figure 4 、 Figure 5 、 Figure 6 and Figure 7, specifically, first place the workpiece on the blank holder plate 3. The upper die moves downward, and the blank holder 1 first contacts the workpiece and applies pressure. At this time, the two halves of the blank holder plate 3 close together as they move downward to form a cavity. Immediately afterwards, the blank holder plate 3 is limited by the third nitrogen spring and no longer moves. Since the initial force of the third nitrogen spring is greater than that of the first nitrogen spring, the blank holder 1 moves upward relative to the upper die holder, and the punch 2 moves downward relative to the blank holder 1, and then stretching begins. Because in the initial state, during stretching, under the limitation of the upper punch 21, the two parts are stretched as a whole. When the stretching reaches the point where the upper punch 21 is completely in contact with the workpiece, the initial force of the third nitrogen spring is greater than the sum of the second nitrogen spring and the first nitrogen spring. The second nitrogen spring corresponding to the upper punch 21 compresses. After compression, as the upper die holder continues to move downward, the lower punch 22 moves downward to continue stretching the remaining part. The initial elastic force of the first resetting member corresponding to the lower punch 22 should be greater than the stretching force required for stretching the remaining part to complete the stretching action. After the stretching action is completed, as the upper die holder continues to move downward, the third nitrogen spring corresponding to the blank holder plate 3 begins to compress, that is, both the upper die and the blank holder plate 3 move downward as a whole and contact the flanging blade block 6 on the lower core 5. Because the flanging blade block 6 is in a situation where it extends beyond the upper end face of the lower core 5 under the action of the second resetting member 7, the flanging blade block 6 is pushed to move downward. The sum of the initial compression forces of all the second resetting members 7 is less than the initial acting force of the third resetting member 8 and the friction force of the spiral groove 51, that is, the flanging blade block 6 slides first, as Figure 4 and Figure 5 shown Figure 4 where Y1 in Figure 5 is the action line of the flanging action surface, and the process is as in Figure 6 shown. Because of the rotation of the lower core 5, the top view of the actual trajectory of the fixed point on the Y1 action line is spiral-like (spatial spiral-like in three-dimensional space), so its front view is as in Figure 7 shown, which is also spiral-like in a plane. After the flanging blade block 6 rotates one cycle (that is, the circumferential angle between adjacent flanging blade blocks 6), the flanging is completed, but the lower core 5 continues to rotate and rotates at least one more cycle for sizing, and finally the stretching and flanging are completed.

[0040] Refer to Figure 9 , the action line Y1 of the flanging blade block 6 is composed of multiple rolling shafts 9. Grooves adapted to the rolling shafts 9 are opened on the action line of the action surface of the flanging blade block 6. Both ends of the rolling shafts 9 are rotatably installed on the grooves and limited by snap rings. The rolling of the rolling shafts 9 is used to replace sliding friction with rolling friction, so as to avoid scratching the surface of the workpiece;

[0041] As one of the embodiments, the cross-sectional line of the outer circumferential surface of the rolling shaft 9 on the flanging tool block 6 is concave toward the axis, that is, the rolling shaft 9 is a columnar body with a large diameter at both ends and a small diameter in the middle. Only the two ends of the two ends are in contact with the workpiece. Each point on each rolling shaft 9 forms a Y1 action line. The bending degree of the cross-sectional depression of the rolling shaft 9 is greater than or equal to the final bending degree of the Y1 action line, so as to prevent multiple points on the rolling shaft 9 from contacting the workpiece and causing protrusions;

[0042] Refer to Figure 10 , as another embodiment, the outer circumferential surface of the rolling shaft 9 on the flanging tool block 6 is convex, that is, the rolling shaft 9 is similar to a spindle structure, and its convexity means that only one point is in contact with the workpiece surface;

[0043] Furthermore, on the basis of the embodiment of the convex rolling shaft 9, the rolling shaft 9 is set to be able to swing at both ends to change the axis position, that is, as Figure 11 , specifically, a tuning fork-shaped mounting frame 10 is installed on the action line of the flanging tool block 6. The installation part of the mounting frame 10 can rotate. The fork part is rotatably installed at both ends of the rolling shaft 9. Furthermore, the rolling shaft 9 can rotate both by itself and around the installation axis of the mounting frame 10. Setting the rolling shaft 9 to be able to change the axis angle can make it roll better, because when the flanging tool block 6 slides and rotates on the lower core 5, its actual sliding angle relative to the workpiece changes. Therefore, this setting method can make it adaptively change the angle, and then only roll and avoid sliding.

[0044] Refer to Figure 4 , in the initial state of the flanging tool block 6, the corner part that is disengaged from the lower punch 22 first is arc-shaped, so as to facilitate sliding and prevent scratches on the punch 2.

[0045] A stamping method for a stamping part stamping device includes the following steps;

[0046] S1 First stretching, the upper punch 21 and the lower punch 22 move downward synchronously relative to the workpiece for stretching;

[0047] S2 Second stretching, after the upper punch 21 completely contacts the workpiece, the lower punch 22 continues to move downward to complete the stretching of the flanging part;

[0048] S3 Flanging, the flanging includes the following two sub-steps:

[0049] A1 Expanding flanging, the lower punch 22 moves downward and drives the flanging tool block 6 to slide. During the rotation of the lower core 5, the flanging tool block 6 expands radially outward and rotates circumferentially to form an overall expansion;

[0050] A2 Shaping, after the expansion is completed, the lower core 5 continues to rotate to drive the flanging tool block 6 to rotate, and then shape the flanging position.

[0051] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0052] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A stamping device for stampings, comprising a blank holder (1) that slides up and down along the die opening direction. A first nitrogen spring is provided between the blank holder (1) and the upper die. A punch (2) mounted on the upper die is slidably arranged at the middle position of the blank holder (1), and it is characterized in that: The punch (2) consists of an upper punch (21) and a lower punch (22). The upper punch (21) and the lower punch (22) are bounded by the middle of the stretching depth. The upper punch (21) is cylindrical and slides with the lower punch (22). A second nitrogen spring is provided between the upper punch (21) and the upper die. A first reset member is provided between the lower punch (22) and the upper die. Below the blank holder (1), a blank holding plate (3) installed on the lower die is provided. A third nitrogen spring is connected between the blank holding plate (3) and the lower die. The blank holding plate (3) is divided into two halves centered on the axis of the lower punch (22). During the downward movement of the blank holding plate (3) in the mold opening direction, the two halves close to form a stretching and flanging cavity. Below the lower punch (22), a screw rod (4) is fixed to the lower die. And a lower core (5) is connected to the screw rod (4) through a spiral groove (51). At least three groups of flanging blade blocks (6) are arranged in a circumferential array on the upper end surface of the lower core (5) centered on the axis. The flanging blade blocks (6) are slidably connected to the lower core (5). A second reset member (7) is provided between the flanging blade blocks (6) and the lower core (5). In the initial state, one end of the flanging blade block (6) extends beyond the upper end surface of the lower core (5). It slides under the contact of the lower punch (22) to flang the workpiece. And during the process of the lower punch (22) contacting the flanging blade block (6), the lower core (5) rotates under the action of the screw rod (4) to make the flanging blade block (6) rotate circumferentially. A third reset member (8) is provided between the lower core (5) and the lower die.

2. The stamping device for stampings according to claim 1, characterized in that: The working surface of the flanging blade block (6) is a curved surface, and the contact with the workpiece at the working surface is a line contact.

3. A stamping device for stampings according to claim 2, characterized in that: A rolling shaft (9) is rotatably installed on the flanging blade block (6). There are multiple groups of the rolling shafts (9). The contact points of the rolling shafts (9) with the workpiece form the working surface to generate rolling pressure.

4. A stamping device for stampings according to claim 3, characterized in that: The circumferential surface of the rolling shaft (9) is concave towards the axis, and the circular peripheral line corresponding to the cross-section passing through the axis always has two-point contact with the workpiece.

5. The stamping device for stampings according to claim 3, characterized in that: The circumferential surface of the rolling shaft (9) is a spindle shape that is convex outward.

6. The stamping device for a stamped part according to claim 5, characterized in that: A tuning fork-shaped mounting bracket (10) rotates on the flanging blade block (6). Both ends of the rolling shaft (9) are rotatably connected to the mounting bracket (10). When the flanging blade block (6) moves spirally, the rolling shaft (9) tilts at an angle according to the shape of the workpiece surface.

7. A stamping device for stampings according to claim 1, characterized in that: The screw rod (4) makes the flanging blade block (6) rotate by an angle of at least twice the circumferential angle between adjacent two flanging blade blocks (6). And when the flanging blade block (6) rotates to the middle of the stroke, the workpiece is flanged.

8. A stamping device for stampings according to claim 1, characterized in that: The initial contact surface between the flanging blade block (6) and the lower punch (22) is an arc surface.

9. The stamping method of a stamping device for stampings according to claim 1, characterized in that, Including the following steps: S1 First stretching, the upper punch (21) and the lower punch (22) move downward synchronously relative to the workpiece for stretching; S2 Second stretching, after the upper punch (21) completely contacts the workpiece, the lower punch (22) continues to move downward to complete the stretching of the flanging part; S2 Flanging, the flanging includes the following two sub-steps: A1 Expanding flanging, the lower punch (22) moves downward and drives the flanging blade block (6) to slide. And during the rotation of the lower core (5), the flanging blade block (6) expands radially outward and rotates circumferentially to form an overall expansion; After the A2 solid type and expansion type are completed, the lower core (5) continues to rotate to drive the flanging cutter block (6) to rotate, thereby solidifying the flanging position.

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