A drawing die mechanism and a stamping method thereof

Abstract

The application provides a drawing die mechanism and a stamping method thereof. The drawing die mechanism adds an upper die pre-pressing module in an upper pressing unit. The upper die pre-pressing module pre-presses the wrinkled part of a plate during stamping. The drawing die mechanism solves the problems of product wrinkling and material stacking under the premise of keeping the original product shape. The drawing die mechanism has novel structure design and high practicability, and greatly shortens the project cycle and reduces the project cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile die stamping, in particular, to a drawing die mechanism and a stamping method thereof. BACKGROUND

[0002] In the stamping process, some parts are prone to gather and wrinkle due to their complex shape, especially when the outer binder ring is in contact. These problems are mainly caused by factors such as limited material flow in complex-shaped parts, uneven binder force, mold design defects, improper material selection and process parameter control. For example, sharp corners or uneven areas can limit the flow of sheet metal, causing local material accumulation; uneven pressure distribution during the binder process can easily cause uneven stretching of the sheet metal. To solve these problems, measures such as optimizing mold design, adjusting process parameters, selecting appropriate materials, and strengthening quality control are usually taken to improve the quality and stability of stamping forming. Over-binder force control, mold design optimization and lubricant use are used to reduce wrinkling. When the traditional stamping process cannot solve the modeling problem, the product is usually required to change the modeling, which will change the overall design style of the vehicle body, have a great impact, and have a huge impact on the project cycle and cost.

[0003] Therefore, there is a need for a special drawing die structure to perfectly solve the problems of product wrinkling and material stacking without changing the product modeling. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide a drawing die mechanism and a stamping method to solve the problems of product wrinkling and material stacking in the traditional drawing process, to ensure the processability and manufacturability of the mold, and to ensure the stability of the product quality and batch stability during production.

[0005] To achieve the above technical effects, the present application adopts the following technical solutions:

[0006] According to a first aspect of the present application, a drawing die mechanism is provided, comprising an upper pressing unit, a lower pressing unit, and a cylinder and a limiting mechanism;

[0007] The upper pressing unit comprises an upper die seat, an upper die cavity and an upper die pre-pressing module. The upper die seat and the upper die cavity are fixedly connected. The upper die pre-pressing module is arranged in the upper die cavity and can move up and down relative to other components of the upper die cavity, for contacting and pressing the sheet metal in a specific area in advance to prevent wrinkling. The upper die seat can drive the upper die cavity and the upper die pre-pressing module to move up and down under the action of a driving device. A connecting pad plate is arranged on the upper die seat. A plurality of pre-pressing nitrogen gas springs are arranged at the bottom of the connecting pad plate. The upper die cavity is fixed on the workbench of a punch press and cooperates with the upper die seat to perform a sheet metal forming operation. The upper die pre-pressing module comprises an upper die pre-pressing block and a pre-pressing block mounting base. The upper die pre-pressing block is mounted on the pre-pressing block mounting base. The pre-pressing block mounting base is supported by the upper die seat and can move up and down with the upper die seat. A plurality of pre-pressing block dead blocks are fixedly connected to the pre-pressing block mounting base.

[0008] The lower pressing unit comprises a draw ring and a drawing punch. The draw ring is arranged around the drawing punch. The draw ring and the drawing punch are arranged to place a stamping sheet metal thereon. The draw ring and the drawing punch can relatively displace.

[0009] The cylinder and the limiting mechanism comprise a cylinder, a T-shaped limiting block and a limiting support column. The limiting support column is fixedly connected to the pre-pressing block mounting base and can move up and down with the upper die seat. The cylinder is connected to the T-shaped limiting block and is located between the draw ring and the limiting support column. The cylinder can drive the T-shaped limiting block to abut against or withdraw from the limiting support column on the draw ring.

[0010] Preferably, the upper die cavity is composed of a plurality of die cavity inserts.

[0011] According to the second aspect of the present application, a stamping method of a drawing die is provided. The stamping method is implemented by using the drawing die mechanism described above. The die stamping process comprises an initial stage, a pre-pressing stage, a forming stage and a resetting stage.

[0012] In the initial stage, the upper pressing unit is located at the upper dead point. The plurality of pre-pressing nitrogen gas springs at the bottom of the connecting pad plate are not compressed and are in a natural state. There is a gap between the plurality of pre-pressing block dead blocks on the pre-pressing block mounting base and the connecting pad plate. In the lower pressing unit, the draw ring and the drawing punch are kept in alignment and there is no relative displacement.

[0013] In the pre-pressing stage, first, the cylinder drives the T-shaped limiting block to be staggered with the limiting support column. Then, the entire upper pressing unit is lowered synchronously under the driving of the upper die seat. In the process of lowering, the die cavity inserts and the draw ring are first closed, the sheet metal is fixed and pressed to prevent the sheet metal from moving during the stamping process. The upper die seat drives the insert die cavity to continue to move downward, and the drawing punch is fixed. The draw ring moves downward relative to the drawing punch. When the upper pressing unit moves downward to a preset distance from the lower dead point, the upper die pre-pressing block contacts the drawing punch in advance and presses the sheet metal thereon to prevent the sheet metal from wrinkling.

[0014] In the forming stage, the upper die pre-pressing block stops descending, the connecting pad plate with the pre-pressing nitrogen gas spring continues descending, and the blank holder in the lower pressing unit also continues descending relative to the drawing punch to the lower dead point; at the lower dead point, the pre-pressing block bumping block is against the connecting pad plate, and the pre-pressing block bumping block makes a strong pressure on the pre-pressing area;

[0015] In the resetting stage, the T-shaped limiting block is driven by the cylinder to abut against the limiting support column, the upper die seat ascends, the pre-pressing block and the pre-pressing block mounting base ascend synchronously with the upper die seat under the action of the T-shaped limiting block, the upper die seat continues ascending to separate the concave die insert from the blank holder, at this time, the height position of the upper die pre-pressing block remains unchanged, the upper die seat continues ascending by a preset distance to make the pre-pressing nitrogen gas spring completely reset and not be compressed any more, and then the upper die pre-pressing block ascends synchronously with the upper die seat to the upper dead point.

[0016] The upper dead point and the lower dead point are respectively the highest point and the lowest point of displacement of the upper die seat and other components in the stamping process.

[0017] Preferably, during the continuous descending process, the pre-pressing block mounting base, the upper die pre-pressing module of the upper die pre-pressing block and the connecting pad plate still maintain synchronous descending, and there is no relative displacement between them.

[0018] Preferably, when the pre-pressing block bumping block makes a strong pressure on the pre-pressing area, there is still a gap between the limiting support column and the blank holder.

[0019] Preferably, the preset distance in the pre-pressing stage and the preset distance in the resetting stage are both 35 mm.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1. The drawing die mechanism provided by the present application is different from the traditional drawing die, the concave die of which is provided with a pre-pressing mechanism for pre-pressing material, thereby solving the problems of product wrinkling and material stacking under the premise of retaining the original product modeling.

[0022] 2. The drawing die mechanism and the stamping method thereof greatly shorten the mold stamping project cycle and reduce the project cost.

[0023] 3. The drawing die mechanism provided by the present application has novel structure design and strong practicability. BRIEF DESCRIPTION OF DRAWINGS

[0024] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0025] Figure 1 Fig. 1 is a schematic structural diagram of the drawing die mechanism in the first embodiment;

[0026] Figure 2 Partial enlarged view of the upper die pre-pressing module of the drawing die mechanism described in the first embodiment;

[0027] Figure 3 Front view of the drawing die mechanism at the lower dead point described in the first embodiment;

[0028] Figure 4 Side view of the drawing die mechanism at the lower dead point described in the first embodiment;

[0029] Figure 5 Front view of the partial structure of the drawing die mechanism at the upper dead point described in the first embodiment;

[0030] Figure 6 Flow chart of the drawing die stamping method described in the second embodiment.

[0031] Reference signs

[0032] 1 - upper die seat

[0033] 2 - concave die insert

[0034] 3 - upper die pre-pressing block

[0035] 4 - blank holder

[0036] 5 - drawing punch

[0037] 6 - connecting pad

[0038] 7 - pre-pressing block mounting base

[0039] 8 - limiting support column

[0040] 9 - air cylinder

[0041] 10 - L-shaped cover plate

[0042] 11 - T-shaped limiting block

[0043] 12 - pre-pressing block dead block

[0044] 13 - pre-pressing nitrogen gas spring

[0045] 14 - lower die seat DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0048] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, all directional indications (such as up, down, left, right, front, back, bottom, etc.) in this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0049] This embodiment provides a drawing die mechanism that prevents product wrinkling and stacking by pre-pressing the wrinkled area in advance, and improves the stress on the sheet metal during the forming process by pre-pressing the product, ultimately achieving the product quality requirements. This special drawing die mechanism perfectly solves the problems of product wrinkling and stacking without changing the product shape, solving problems that traditional drawing processes cannot solve.

[0050] like Figures 1 to 5 As shown, the drawing die mechanism consists of an upper pressing unit, a lower pressing unit, and a limiting mechanism.

[0051] The upper pressing unit comprises an upper die seat 1, an upper die cavity and an upper die pre-pressing module, the upper die seat 1 and the upper die cavity are fixedly connected, and the upper die seat 1 is used for driving the upper die cavity and the upper die pre-pressing module to move up and down. The upper die seat 1 is connected with a driving device of a stamping equipment, and can drive the upper die cavity and the upper die pre-pressing module to move up and down under the action of the driving device; a connecting pad plate 6 is arranged on the upper die seat 1, and a plurality of pre-pressing nitrogen gas springs 13 are arranged at the bottom of the connecting pad plate 6, when in the initial stage, the pre-pressing nitrogen gas springs 13 are not compressed, and are in a natural extension and contraction state. The upper die cavity is composed of a plurality of die cavity inserts 2, the plurality of die cavity inserts 2 are fixed on a workbench of a punch press, and cooperate with the upper die seat 1 to perform a forming operation on a plate material. The upper die pre-pressing module is used for contacting and pressing a specific area of the plate material in advance to prevent wrinkling, and comprises an upper die pre-pressing block 3, a pre-pressing block mounting base 7 and a pre-pressing block dead block 12. The upper die pre-pressing block 3 is mounted on the pre-pressing block mounting base 7, and is used for contacting and pressing the plate material in advance to prevent wrinkling during the stamping process. The pre-pressing block mounting base 7 is used for supporting and fixing the upper die pre-pressing block 3, and the pre-pressing block mounting base 7 is supported by the upper die seat 1 and can move up and down with the upper die seat 1. A plurality of pre-pressing block dead blocks 12 are fixedly connected to the pre-pressing block mounting base 7.

[0052] The lower pressing unit comprises a lower die seat 14, a blank holder 4 and a drawing punch 5, the blank holder 4 and the drawing punch 5 are arranged on the lower die seat 14, the blank holder 4 is arranged on the periphery of the drawing punch 5, the blank holder 4 and the drawing punch 5 are used for placing a drawing plate material, and the drawing punch 5 is fixedly arranged on a punch press and cannot move up and down. The drawing plate material on the drawing punch 5 is pre-pressed by the upper die pre-pressing block 3. In the process of moving down, the die cavity inserts 2 and the blank holder 4 are closed, the plate material is fixed and pressed tightly, and the plate material is prevented from moving in the stamping process. At the same time, the blank holder 4 and the drawing punch 5 can relatively displace under the pressing action of the die cavity inserts 2.

[0053] The cylinder and limiting mechanism consists of a cylinder 9, a T-shaped limiting block 11, and a limiting support column 8. The limiting support column 8 is fixedly connected to the pre-pressing block mounting base 7 and can move up and down above the pressure ring 4 under the drive of the upper mold base 1. When the limiting support column 8 moves down to the lower dead point with the pre-pressing block mounting base 7, there is still a gap between the bottom of the limiting support column 8 and the pressure ring 4. The cylinder 9 is connected to the T-shaped limiting block 11 and is located on both sides of the pressure ring 4. The T-shaped limiting block 11 is an inverted T-shape, and both sides are covered with L-shaped cover plates 10 that are adapted to its inverted T-shape. The cylinder 9 can drive the T-shaped limiting block 11 and control its switching between the working position and the non-working position. The working position refers to the T-shaped limiting block 11 being located below the limiting support column 8, so that the T-shaped limiting block 11 abuts against the limiting support column 8 and the pre-pressing block mounting base 7 on the pressure ring 4; the non-working position refers to the T-shaped limiting block 11 being offset from the limiting support column 8. Driven by the cylinder 9, the T-shaped limiting block 11 switches its working position, ensuring that it abuts against the limiting support column 8, thus ensuring that the upper die and pressure ring 4 move upwards simultaneously, preventing damage to the product.

[0054] The entire die stamping process includes the initial stage, the pre-pressing stage, the forming stage, and the reset stage. The top dead center and bottom dead center are the highest and lowest displacement points of the upper die holder 1 and other components during the stamping process, respectively.

[0055] In the initial stage, the upper pressing unit, lower pressing unit, and limiting mechanism are all in their initial states. The upper pressing unit is located at the top dead center, and all its components are in their initial states, such as... Figure 5 As shown, the pre-compressed nitrogen springs 13 on the bottom surface of the connecting pad 6 are not compressed and are in their natural state. There is a certain gap between the pre-compressed block dead blocks 12 on the pre-compressed block mounting base 7 and the connecting pad 6. In the pressing unit, the pressure ring 4 and the drawing punch 5 remain relatively flush and there is no relative displacement.

[0056] In the pre-pressing stage, first, the cylinder 9 drives the T-shaped limiting block 11 to the non-working position, ensuring that the T-shaped limiting block 11 is staggered with the limiting support column 8. Then the upper pressing unit starts to move downward from the lower dead point, under the action of the upper die seat 1, the connecting pad plate 6 carries the pre-pressing nitrogen gas spring 13, the pre-pressing block mounting base 7 carries the upper die pre-pressing block 3 and the concave die block 2 starts to descend synchronously, and there is no relative displacement between them. During the downward movement, the concave die block 2 and the blank holder 4 are closed first, fixing and pressing the sheet metal to prevent the sheet metal from moving during stamping. The upper die seat 1 drives the die block concave die 2 to continue to descend, the drawing punch 5 is fixed, the blank holder 4 moves downward relative to the drawing punch 5, and during the continuous downward movement, the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 of the upper die pre-pressing block and the connecting pad plate 6 still keep synchronous downward movement, and there is no relative displacement between them. When descending to the bottom 35mm, the upper die pre-pressing block 3 contacts the drawing punch 5 in advance and presses the sheet metal on it to prevent the sheet metal from wrinkling, at this time the upper die pre-pressing block 3 stops descending.

[0057] In the forming stage, since the upper die pre-pressing block 3 has been pressed on the fixed drawing punch 5, the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 will not continue to descend, the connecting pad plate 6 carries the pre-pressing nitrogen gas spring 13 and still continues to descend, and the blank holder 4 in the lower pressing unit also continues to descend relative to the drawing punch 5. During the continuous downward movement, the upper die pre-pressing block 13 starts to be compressed, and the gap between the connecting pad plate 6 and the pre-pressing block dead block 12 starts to decrease to zero, that is, when the connecting pad plate 6 contacts the pre-pressing block dead block 12 under the action of the upper die seat 1, the entire upper pressing unit and the blank holder 4 are descended to the lower dead point. The concave die block 2 presses the blank holder 4 to make relative displacement between the blank holder 4 and the drawing punch 5, so as to form the profile of the whole sheet metal. At the same time, the pre-pressing block dead block 12 at the lower dead point strongly presses the pre-pressing area under the upper die pre-pressing block 3 to ensure the forming quality of the sheet metal. At this time, there is still a gap between the limiting support column 8 and the blank holder 4.

[0058] In the reset stage, first, the T-shaped limiting block 11 is driven by the cylinder 9 to the working position to make the T-shaped limiting block 11 abut against the limiting support column 8. Then the upper die seat 1 drives the concave die insert 2 and the connecting pad plate 6 to go up, and the blank holder 4 goes up synchronously with the concave die insert 2 to the initial height. Since the T-shaped limiting block 11 is arranged on the upper surface of the blank holder 4, the T-shaped limiting block 11 drives the limiting support column 8 to go up synchronously with the blank holder 4, and the limiting support column 8 drives the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 to go up synchronously with the upper die seat 1, that is, the blank holder 4, the upper die pre-pressing block 3 and the concave die insert 2 go up synchronously under the driving of the upper die seat 1. The upper die pre-pressing block 3 and the pre-pressing block mounting base 7 go up synchronously with the upper die seat 1 under the action of the T-shaped limiting block 11, so as to avoid that the upper die pre-pressing block 3 is pressed to damage the product. When the blank holder 4 goes up to the initial height, the blank holder 4 is separated from the concave die insert 2, the concave die insert 2 continues to go up, the blank holder 4 no longer goes up, and the upper die pre-pressing block 3 also temporarily stops going up. The upper die seat 1 continues to go up by 35 mm. In this process, since the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 no longer go up, and the connecting pad plate 6 always goes up with the upper die seat 1, the pre-pressing nitrogen gas spring 13 starts to reset to the natural state, and a gap starts to appear between the connecting pad plate 6 and the pre-pressing block mounting base 7 to the initial state. After the pre-pressing nitrogen gas spring 13 resets to the initial state, the upper die pre-pressing block 3 and the upper die seat 1 continue to go up synchronously to the upper dead center. At this time, the cylinder 9 drives the T-shaped limiting block 11 to be in the non-working position, so as to ensure that the T-shaped limiting block 11 is disengaged from the limiting support column 8, and a working cycle is completed. In the whole stamping process, the T-shaped limiting block 11 is driven by the cylinder 9 to switch between the working position and the non-working position, so as to realize continuous and normal pressing of the product, which greatly retains the original design of the product, and perfectly solves the problems of product wrinkling and material stacking.

[0059] Second embodiment

[0060] As shown in Figure 6 , the present embodiment provides a stamping method of a drawing die mechanism, which is implemented by using the drawing die mechanism described in the first embodiment. The stamping process includes an initial stage, a pre-pressing stage, a forming stage and a reset stage.

[0061] In the initial stage, the upper pressing unit, the lower pressing unit and the limiting mechanism are all in the initial state, and the upper pressing unit is located at the upper dead center, and the components thereof are all in the initial state, as shown in Figure 4 , the pre-pressing nitrogen gas springs 13 arranged on the bottom surface of the connecting pad plate 6 are not compressed and are in the natural state, and there is a certain gap between the pre-pressing block dead block 12 on the pre-pressing block mounting base 7 and the connecting pad plate 6. In the lower pressing unit, the blank holder 4 and the drawing punch 5 are kept in alignment and there is no relative displacement.

[0062] In the pre-pressing stage, first, the cylinder 9 drives the T-shaped limiting block 11 to be in the non-working position, ensuring that the T-shaped limiting block 11 is staggered with the limiting support column 8. Then the upper pressing unit starts to move downward from the upper dead point, under the driving of the upper die seat 1, the connecting pad plate 6 is synchronously lowered with the pre-pressing nitrogen gas spring 13, the pre-pressing block mounting base 7 is synchronously lowered with the upper die pre-pressing block 3 and the concave die block 2, and there is no relative displacement between them. During the downward movement, the concave die block 2 is first closed with the blank holder 4, fixing and pressing the sheet metal to prevent the sheet metal from moving during stamping. The upper die seat 1 drives the die block concave die 2 to continue to move downward, the drawing male die 5 is fixed, the blank holder 4 moves downward relative to the drawing male die 5, and during the continuous downward movement, the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 of the upper die pre-pressing block continue to move downward synchronously, and there is no relative displacement between them. When the downward movement reaches 35mm before the bottom, the upper die pre-pressing block 3 contacts the drawing male die 5 and presses the sheet metal thereon to prevent the sheet metal from wrinkling, at which time the upper die pre-pressing block 3 stops moving downward.

[0063] In the forming stage, since the upper die pre-pressing block 3 has been pressed on the fixed drawing male die 5, the pre-pressing block mounting base 7 and the upper die pre-pressing block 3 will not continue to move downward, the connecting pad plate 6 continues to move downward with the pre-pressing nitrogen gas spring 13, and the blank holder 4 in the lower pressing unit also continues to move downward relative to the drawing male die 5. During the continuous downward movement, the upper die pre-pressing block 13 starts to be compressed, and the gap between the connecting pad plate 6 and the pre-pressing block dead block 12 starts to decrease to zero, i.e. when the connecting pad plate 6 contacts the pre-pressing block dead block 12 under the driving of the upper die seat 1, the entire upper pressing unit and the blank holder 4 are lowered to the lower dead point, as shown in Figure 3 Figure 4 The concave die block 2 presses the blank holder 4 to make relative displacement between the blank holder 4 and the drawing male die 5, so as to form the profile of the whole sheet metal. At the same time, the pre-pressing block dead block 12 at the lower dead point strongly presses the pre-pressing area under the upper die pre-pressing block 3, ensuring the forming quality of the sheet metal. At this time, there is still a gap between the limiting support column 8 and the blank holder 4.

[0064] During the reset phase, cylinder 9 first moves T-shaped limit block 11 to the working position, causing it to press against limit support column 8. Then, upper mold base 1 moves die insert 2 and connecting pad 6 upwards. Pressure ring 4 moves synchronously with die insert 2 to its initial height. Since T-shaped limit block 11 is installed on pressure ring 4, it moves limit support column 8 upwards synchronously with pressure ring 4. Limit support column 8 then moves pre-pressure block mounting base 7 and upper mold pre-pressure block 3 upwards synchronously with upper mold base 1. In other words, under the action of upper mold base 1, pressure ring 4, upper mold pre-pressure block 3, and die insert 2 move upwards synchronously. Upper mold pre-pressure block 3 and pre-pressure block mounting base 7 move synchronously with upper mold base 1 under the action of T-shaped limit block 11, preventing upper mold pre-pressure block 3 from damaging the product. When the pressure ring 4 rises to its initial height, it separates from the die insert 2. The die insert 2 continues to rise, while the pressure ring 4 stops rising, and the upper die pre-pressure block 3 also temporarily stops rising. The upper die base 1 continues to rise 35mm. During this process, since the pre-pressure block mounting base 7 and the upper die pre-pressure block 3 no longer rise, while the connecting pad 6 continues to rise with the upper die base 1, the pre-pressure nitrogen spring 13 begins to reset to its initial height. Figure 5 As shown in the natural state, a gap begins to appear between the connecting pad 6 and the pre-compression block mounting base 7, returning to the initial state. After the pre-compression nitrogen spring 13 returns to its initial state, the upper die pre-compression block 3 and the upper die base 1 continue to move synchronously upward to the top dead center. At this time, the cylinder 9 drives the T-shaped limit block 11 to the non-working position, ensuring that the T-shaped limit block 11 is misaligned with the limit support column 8, completing one working cycle. Throughout the stamping process, the cylinder 9 drives the T-shaped limit block 11 to switch between the working and non-working positions, ultimately achieving continuous and normal pressing of parts. This greatly preserves the original shape design of the product and perfectly solves the problems of product wrinkling and material stacking.

[0065] The specific embodiments of the present invention have been described above. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A draw die mechanism characterized by, The upper pressing unit, the lower pressing unit, the air cylinder and the limiting mechanism are included. The upper pressing unit includes an upper die seat, an upper die cavity and an upper die pre-pressing module. The upper die seat and the upper die cavity are fixedly connected. The upper die pre-pressing module is arranged in the upper die cavity and can move up and down relative to other upper die cavity components, so as to contact and press a specific area of the plate in advance and prevent wrinkling. The upper die seat can drive the upper die cavity and the upper die pre-pressing module to move up and down under the action of a driving device. A connecting pad plate is arranged on the upper die seat. A plurality of pre-pressing nitrogen gas springs are arranged at the bottom of the connecting pad plate. The upper die cavity is fixed on the workbench of a punch press and cooperates with the upper die seat to perform a forming operation on the plate. The upper die pre-pressing module includes an upper die pre-pressing block and a pre-pressing block mounting base. The upper die pre-pressing block is mounted on the pre-pressing block mounting base. The pre-pressing block mounting base is supported by the upper die seat and can move up and down with the upper die seat. A plurality of pre-pressing block dead blocks are fixedly connected to the pre-pressing block mounting base. The lower pressing unit includes a press ring and a drawing punch. The press ring is arranged around the drawing punch. The press ring and the drawing punch are used to place the stamping plate thereon. The press ring and the drawing punch can relatively displace. The air cylinder and the limiting mechanism include an air cylinder, a T-shaped limiting block and a limiting support column. The limiting support column is fixedly connected to the pre-pressing block mounting base and can move up and down with the pre-pressing block mounting base under the driving of the upper die seat. The air cylinder is connected to the T-shaped limiting block and is located between the press ring and the limiting support column. The air cylinder can drive the T-shaped limiting block to abut against or withdraw from the limiting support column on the press ring.

2. The draw die mechanism of claim 1 wherein, The upper die cavity is composed of a plurality of die inserts.

3. A method of stamping a draw die, characterized by, The drawing die mechanism is implemented by any one of claims 1 to 2. The die stamping process includes an initial stage, a pre-pressing stage, a forming stage and a resetting stage. In the initial stage, the upper pressing unit is located at the upper dead point. The plurality of pre-pressing nitrogen gas springs at the bottom of the connecting pad plate are not compressed and are in a natural state. There is a gap between the plurality of pre-pressing block dead blocks on the pre-pressing block mounting base and the connecting pad plate. In the lower pressing unit, the press ring and the drawing punch are kept in alignment and there is no relative displacement. In the pre-pressing stage, first, the air cylinder drives the T-shaped limiting block to be staggered with the limiting support column. Then, the entire upper pressing unit is lowered synchronously under the driving of the upper die seat. In the process of lowering, the die inserts and the press ring are first closed, the plate is fixed and pressed tightly to prevent the plate from moving during the stamping process. The upper die seat drives the die inserts to continue to move downward, and the drawing punch is fixed, so that the press ring moves downward relative to the drawing punch. When the upper pressing unit moves downward to a preset distance from the lower dead point, the upper die pre-pressing block contacts the drawing punch in advance and presses the plate thereon to prevent the plate from wrinkling. In the forming stage, the upper die pre-pressing block stops moving downward, the connecting pad plate with the pre-pressing nitrogen gas springs continues to move downward, and the press ring in the lower pressing unit also continues to move downward relative to the drawing punch to the lower dead point. At the lower dead point, the pre-pressing block dead blocks abut against the connecting pad plate, and the pre-pressing block dead blocks make a strong pressure on the pre-pressing area. In the reset stage, the cylinder drives the T-shaped limit block to stop against the limit support column, the upper die seat goes up, and the pre-press block and the pre-press block mounting base go up synchronously under the action of the T-shaped limit block, the upper die seat goes up to the point where the concave die insert separates from the blank holder, at this time the height position of the upper die pre-press block remains unchanged, the upper die seat continues to go up by a preset distance to make the pre-press nitrogen gas spring fully reset and no longer be compressed, then the upper die pre-press block goes up synchronously with the upper die seat to the upper dead point; The upper dead point and the lower dead point are respectively the highest point and the lowest point of the displacement of the upper die seat and other components in the stamping process.

4. The method of pressing a draw die according to claim 3, wherein In the process of continuing to go down, the pre-press block mounting base and the upper die pre-press module of the upper die pre-press block and the connecting pad plate still maintain synchronous downward movement, and there is no relative displacement between them.

5. The method of pressing a draw die according to claim 3, wherein When the pre-press block dead block does strong pressure on the pre-press area, there is still a gap between the limit support column and the blank holder.

6. The method of pressing a draw die according to claim 3, wherein The preset distance in the pre-press stage and the reset stage is 35mm.

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