A drawing and flanging die and a method for controlling springback of a flange of a sheet metal part

Abstract

The application relates to a drawing and flanging die and a method for controlling flanging springback of a sheet metal part, which comprises a drawing punch and a drawing die, a blanking gap is arranged between the drawing punch and the drawing die, the blanking gap comprises a plane gap section, a flanging round corner gap section and a flanging cross section gap section which are sequentially communicated, the flanging cross section gap section comprises a flanging springback small straight line gap section, one end of the flanging springback small straight line gap section is communicated with the flanging round corner gap section, the flanging springback small straight line gap section is inclined and extended from the connection position of the flanging round corner gap section to the direction close to the drawing punch, and the flanging springback small straight line gap section is used for preforming a preformed flanging springback small straight line section D1 on a flanging cross section section C part of the sheet metal part. The preformed flanging springback small straight line section D1 has a smaller springback tendency, so that the sheet metal part can keep the shape and size required by design after unloading.

Description

Technical Field

[0001] The present application relates to the field of automobile cover mold tooling, and in particular to a drawing and flanging mold and a method for controlling the flanging springback of a sheet metal part. Background Art

[0002] In the stamping process, flanging is a common processing method. The ideal flanging state is as follows Figure 1 As shown, the cross-sectional shape of the sheet metal part 1 includes a sheet metal plane section A, a flanged corner section B and a flanged cross-sectional section C. The corresponding drawing die is as follows Figure 2 As shown in the figure, due to the plastic deformation of the material and the influence of internal stress during the flanging process, springback often occurs, resulting in the size and shape of the stamping parts not meeting the requirements.

[0003] Flanging springback refers to the phenomenon in which, after the external load is removed during the stamping process, the material in the plastic deformation zone deforms due to residual stress, causing the sheet metal part to deform. This phenomenon is caused by the elastic recovery of the sheet metal's elastic deformation zone and the elastic recovery of the elastically deformed portion of the material within the plastic deformation zone, causing the shape and size of the sheet metal part to change in the opposite direction of the deformation during the loading process.

[0004] This flanging springback problem is a difficult point in the sheet metal stamping process, such as Figure 3 As shown, the ideal state C of the flange cross-section shape becomes a straight line segment C1 with a small flange springback, a straight line segment C3 with a large flange springback, and a transition straight line segment C2 between segments C1 and C3.

[0005] In the related art, the traditional solution is to add a side shaping process mold to reduce the flanging springback through side shaping. Since the sheet metal parts need to add a set of molds to the side shaping process, the mold structure becomes complicated and the cost increases. Summary of the Invention

[0006] The present application provides a drawing flanging die and a method for controlling the flanging springback of sheet metal parts, which can avoid the traditional method of adding a side shaping process die and reduce the flanging springback through side shaping. Since the sheet metal parts need to add a set of dies for the side shaping process, the die structure becomes complicated and the cost increases.

[0007] In a first aspect, an embodiment of the present application provides a drawing and flanging die, comprising:

[0008] A drawing punch and a drawing die, wherein a blanking gap is provided between the drawing punch and the drawing die, and the blanking gap comprises a plane gap section, a flanged corner gap section and a flanged section gap section which are connected in sequence;

[0009] The flanging section gap section includes a straight line gap section with small flanging springback, one end of which is connected to the flanging rounded corner gap section, and the straight line gap section with small flanging springback extends obliquely from the connection with the flanging rounded corner gap section toward the direction close to the drawing punch, and the straight line gap section with small flanging springback is used to pre-shape the flanging section section C of the sheet metal part into a pre-shaped straight line section D1 with small flanging springback.

[0010] In combination with the first aspect, in one embodiment, a portion where one end of the straight gap section with a small amount of flanging rebound connects with one end of the flanging rounded gap section is chamfered.

[0011] In combination with the first aspect, in one embodiment, the flange cross-section gap segment includes a linear gap segment with a large flange rebound amount, and one end of the linear gap segment with a large flange rebound amount is connected to one end of the linear gap segment with a small flange rebound amount;

[0012] The straight line gap section with large flanging springback extends obliquely from the connection with the straight line gap section with small flanging springback toward the direction close to the drawing punch, and the straight line gap section with large flanging springback is used to pre-shape the other part of the flanging section segment C of the sheet metal part into a pre-shaped straight line segment D3 with large flanging springback.

[0013] In combination with the first aspect, in one embodiment, the inclination angle of the linear gap section with a small flanging rebound amount is smaller than the inclination angle of the linear gap section with a large flanging rebound amount.

[0014] In combination with the first aspect, in one embodiment, the flange section gap segment also includes a transition straight line gap segment, which is connected between the straight line gap segment with small flange rebound amount and the straight line gap segment with large flange rebound amount, and the transition straight line gap segment is parallel to the plane gap segment. The transition straight line gap segment is used to pre-shape the remaining part of the flange section segment C of the sheet metal part into a pre-shaped transition straight line segment D2.

[0015] In combination with the first aspect, in one embodiment, a chamfer is provided at a connection point between one end of the transition straight line gap segment and the other end of the straight line gap segment with small flanging rebound amount.

[0016] In combination with the first aspect, in one embodiment, a chamfer is provided at a connection point between the other end of the transition straight line gap section and one end of the straight line gap section with large flanging rebound amount.

[0017] In combination with the first aspect, in one embodiment, the drawing and flanging die further includes:

[0018] A flanging punch and a flanging die, wherein a reserved groove is provided on the side of the flanging punch facing the flanging die, and the reserved groove is used to accommodate the pre-shaped transition straight line segment D2 and the pre-shaped flanging large springback straight line segment D3 formed by pre-shaping the sheet metal part.

[0019] In a second aspect, embodiments of the present application provide a method for controlling the springback of a sheet metal part flanging using the draw flanging die described in some of the above embodiments, comprising the following steps:

[0020] The sheet metal part is drawn using a drawing punch and a drawing die. During the drawing process, the flanging section C of the sheet metal part is pre-shaped into a pre-shaped flanging springback small straight line segment D1 using the flanging springback small straight line gap segment.

[0021] The sheet metal parts are stamped and flanging are performed using a flanging punch and a flanging die to complete the drawing and flanging process of the sheet metal parts.

[0022] In conjunction with the second aspect, in one embodiment, before the sheet metal part is stamped and flanging is performed using the flanging punch and the flanging die to complete the drawing and flanging process of the sheet metal part, the method further includes:

[0023] Cut out the stretched area of ​​the sheet metal.

[0024] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0025] The flange section gap section includes a linear gap section with low flange springback. One end of this gap section connects to the flange radius gap section and gradually approaches the drawing punch along its length. This design allows the flange section C of the sheet metal part to be pre-shaped into a pre-shaped linear segment D1 with low flange springback during the stamping process. By designing the linear gap section with low flange springback, the die can pre-shape the flange portion of the sheet metal part during the drawing and stamping process, effectively reducing springback. The pre-shaped linear segment D1 with low flange springback has a reduced springback tendency, allowing the sheet metal part to more accurately maintain the desired shape and dimensions after unloading. Reducing springback directly improves the dimensional accuracy and shape stability of the sheet metal part, thereby enhancing its overall quality. This helps reduce scrap and rework caused by springback, thereby lowering production costs. Compared to the traditional method of reducing springback by adding a side shaping die, this improved technology does not require additional die components, thereby simplifying the die structure. This reduces mold manufacturing and maintenance costs and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 It is a structural diagram of the ideal state of flanging of sheet metal parts;

[0028] Figure 2 Schematic diagram of the cross-sectional structure of a drawing die in the prior art;

[0029] Figure 3 It is a schematic diagram of the structure of the sheet metal part in the springback state after stamping and flanging;

[0030] Figure 4 Schematic diagram of the cross-sectional structure of the drawing die in this application;

[0031] Figure 5 This is a schematic diagram of the structure of the sheet metal part after pre-shaping by the drawing die in this application;

[0032] Figure 6 This is a schematic diagram of the cross-sectional structure of the flanging die in this application.

[0033] In the figure: A, sheet metal plane segment; B, flange fillet segment; C, flange cross-section segment; C1, straight line segment with small flange springback; C2, transition straight line segment; C3, straight line segment with large flange springback; D, pre-shaped flange cross-section segment; D1, straight line segment with small pre-shaped flange springback; D2, pre-shaped transition straight line segment; D3, straight line segment with large pre-shaped flange springback;

[0034] 1. Sheet metal; 2. Drawing punch; 3. Drawing die; 4. Blanking gap; 41. Plane gap section; 42. Flanging radius gap section; 43. Flanging section gap section; 431. Straight line gap section with small flanging springback; 432. Transition straight line gap section; 433. Straight line gap section with large flanging springback; 5. Flanging punch; 51. Reserved groove; 6. Flanging die. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] It should be understood that flanging is a common processing method in stamping process. The ideal flanging state of sheet metal part 1 is as follows: Figure 1 As shown, the cross-sectional shape of the sheet metal part 1 includes a sheet metal plane section A, a flanged corner section B and a flanged cross-sectional section C. The corresponding drawing die is as follows Figure 2 As shown, due to the plastic deformation and internal stress of the sheet metal part 1 during the flanging process, springback often occurs, resulting in the size and shape of the stamped part not meeting the requirements.

[0037] Flanging springback refers to the phenomenon in which, after the external load is removed during the stamping process, the material in the plastic deformation zone deforms due to residual stress, causing the sheet metal part to deform. This phenomenon is caused by the elastic recovery of the sheet metal's elastic deformation zone and the elastic recovery of the elastically deformed portion of the material within the plastic deformation zone, causing the shape and size of the sheet metal part to change in the opposite direction of the deformation during the loading process.

[0038] This flanging springback problem is a difficult point in the sheet metal stamping process, such as Figure 3 As shown, the ideal state C of the flange cross-section shape becomes a straight line segment C1 with a small flange springback, a straight line segment C3 with a large flange springback, and a transition straight line segment C2 between segments C1 and C3.

[0039] Among them, the traditional solution is to add a side shaping process mold to reduce the flanging springback through side shaping. Since the sheet metal parts need to add a set of molds to the side shaping process, the mold structure is complicated and the cost increases.

[0040] The embodiment of the present application provides a drawing flanging die and a method for controlling the flanging springback of a sheet metal part, which can avoid the traditional method of adding a side shaping process die and reducing the flanging springback through side shaping. Since the sheet metal part needs to add a set of die for the side shaping process, the die structure becomes complicated and the cost increases.

[0041] First, as Figure 4 As shown, an embodiment of the present application provides a drawing and flanging die, which includes: a drawing punch 2 and a drawing die 3, a blanking gap 4 is arranged between the drawing punch 2 and the drawing die 3, and the blanking gap 4 includes a plane gap section 41, a flanging radius gap section 42 and a flanging section gap section 43 connected in sequence; the flanging section gap section 43 includes a straight line gap section 431 with small flanging rebound, one end of the straight line gap section 431 with small flanging rebound is connected to the flanging radius gap section 42, and the straight line gap section 431 with small flanging rebound extends obliquely from the connection with the flanging radius gap section 42 toward the direction close to the drawing punch 2, and the straight line gap section 431 with small flanging rebound is used to pre-shape the flanging section section C of the sheet metal part 1 into a pre-shaped flanging rebound straight line section D1 with small flanging rebound.

[0042] In this embodiment, the mold includes a drawing punch 2 and a drawing die 3, and a blanking gap 4 is provided between the two. The blanking gap 4 includes three parts, a plane gap section 41, a flanging radius gap section 42 and a flanging section gap section 43. This segmented design helps to more accurately control the deformation of the material during the stamping process. The flanging section gap section 43 further includes a straight line gap section 431 with a small flanging rebound amount. One end of the gap section is connected to the flanging radius gap section 42 and gradually approaches the drawing punch 2 along its length. This design enables the flanging section section C of the sheet metal part 1 to be pre-shaped into a pre-shaped straight line section D1 with a small flanging rebound amount during the stamping process, such as Figure 5 As shown. Through the design of the straight gap section 431 with small flanging rebound, the mold can pre-shape the flanging part of the sheet metal 1 during the drawing and stamping process, thereby effectively reducing the rebound amount. The pre-shaped straight segment D1 with small flanging rebound after pre-shaping has a smaller rebound tendency, so that the sheet metal 1 can more accurately maintain the shape and size required by the design after unloading. Reducing rebound directly improves the dimensional accuracy and shape stability of the sheet metal 1, thereby improving the overall quality of the sheet metal 1. This helps to reduce the scrap rate and rework rate caused by rebound problems and reduce production costs. Compared with the traditional method of adding a side shaping process mold to reduce rebound, the improved technical means does not require additional mold components, thereby simplifying the mold structure. This reduces the manufacturing and maintenance costs of the mold and improves production efficiency. In summary, the improved technical means effectively solves the rebound problem in the subsequent flanging forming process by optimizing the design of the blanking gap 4, especially the structure of the flanging section gap section 43. This not only improves the quality and production efficiency of the sheet metal part 1, but also simplifies the mold structure, reduces production costs, and enhances the adaptability of the mold.

[0043] In combination with the first aspect, in one embodiment, Figure 4 As shown, the connection point between one end of the straight gap section 431 with small flanging rebound amount and one end of the flanging rounded gap section 42 is chamfered.

[0044] In this embodiment, Figure 4As shown, the connection between one end of the linear gap section 431 (low springback) and one end of the rounded gap section 42 is designed with a chamfered corner. This design not only takes into account the mold's manufacturing processability, but also fully considers the stress distribution of the material during the stamping process. The chamfered corner design facilitates smoother stamping of the sheet metal part 1 and reduces stress concentration caused by sharp corners, thereby improving the forming quality of the sheet metal part. Sharp corners often cause stress concentration, increasing the risk of material cracking or springback. The chamfered corner design effectively disperses stress, reducing these risks, thereby improving the forming stability and dimensional accuracy of the sheet metal part 1. The chamfered corner design also reduces wear and damage to the mold during the stamping process, extending the mold's service life. This is because rounded corners are less likely to cause stress concentration and wear, reducing the frequency of mold maintenance and replacement. The chamfered corner design, combined with the design of the linear gap section 431 (low springback) gradually approaching the drawing punch 2, further optimizes springback control. This combined design more precisely guides material deformation, thereby more effectively reducing springback. In summary, by adopting a chamfered corner design to connect the linear gap section 431 with small flanging springback amount and the flanging rounded corner gap section 42, stress concentration is reduced, the mold life is improved, and the control of springback is further optimized.

[0045] In combination with the first aspect, in one embodiment, Figure 4 As shown, the flanging section gap segment 43 includes a straight line gap segment 433 with a large flanging rebound amount, and one end of the straight line gap segment 433 with a large flanging rebound amount is connected to one end of the straight line gap segment 431 with a small flanging rebound amount; the straight line gap segment 433 with a large flanging rebound amount extends obliquely from the connection with the straight line gap segment 431 with a small flanging rebound amount toward the direction close to the drawing punch 2, and the straight line gap segment 433 with a large flanging rebound amount is used to pre-shape the flanging section segment C of the sheet metal part 1 into a pre-shaped straight line segment D3 with a large flanging rebound amount of the flanging section segment D.

[0046] In this embodiment, Figure 4 As shown, the flange cross-section gap segment 43 includes not only the straight line gap segment 431 with small flange springback, but also a new straight line gap segment 433 with large flange springback. One end of the straight line gap segment 433 with large flange springback is connected to one end of the straight line gap segment 431 with small flange springback, forming a continuous gap segment. Along the length direction of the straight line gap segment 433 with large flange springback, and gradually away from the flange fillet gap segment 42, the gap segment gradually approaches the drawing punch 2. This design allows the flange cross-section segment C of the sheet metal part 1 to be pre-shaped by the straight line gap segment 431 with small flange springback, and further shaped by the straight line gap segment 433 with large flange springback, and finally pre-shaped into the pre-shaped straight line segment D3 with large flange springback, as shown in FIG. Figure 5As shown. By introducing the straight gap segment 433 with large flanging rebound, segmented control of springback is achieved. First, the straight gap segment 431 with small flanging rebound performs preliminary pre-shaping on the sheet metal part 1 to reduce the initial springback. Subsequently, the straight gap segment 433 with large flanging rebound is further shaped to ensure that the sheet metal part 1 can more accurately maintain the shape and size required by the design after unloading. The segmented shaping design enables each gap segment to focus more on its specific shaping task, thereby improving the accuracy and effect of the shaping. The straight gap segment 431 with small flanging rebound is mainly responsible for reducing the springback of the transition straight segment C2 and the straight segment C3 with large flanging rebound, while the straight gap segment 433 with large flanging rebound is responsible for further reducing the springback of the straight segment C3 with large flanging rebound, ensuring that the final shape and size of the sheet metal part 1 meet the requirements.

[0047] In combination with the first aspect, in one embodiment, Figure 4 As shown, the inclination angle of the straight gap segment 431 with small flanging rebound is smaller than the inclination angle of the straight gap segment 433 with large flanging rebound, that is, with the length direction of the planar gap segment 41 as the X-axis, and the stamping direction of the drawing punch 2 and the drawing die 3 as the Y-axis, the slope of the straight gap segment 431 with small flanging rebound is smaller than the slope of the straight gap segment 433 with large flanging rebound.

[0048] In this embodiment, Figure 4 In the figure, a coordinate system is defined with the length direction of the plane gap segment 41 as the X-axis and the stamping direction of the drawing punch 2 and the drawing die 3 as the Y-axis. In this coordinate system, the slope of the linear gap segment 431 with a small flanging springback is designed to be smaller than the slope of the linear gap segment 433 with a large flanging springback. This means that during the stamping process, the first step is to pass through a linear gap segment 431 with a small slope and a small flanging springback, and then pass through a linear gap segment 433 with a large slope and a large flanging springback. By designing gap segments with different slopes, such as Figure 3As shown, the smaller slope of the linear gap segment 431 with small flanging springback helps the subsequent transition linear segment C2 and the linear segment C3 with large flanging springback both have smaller rebound compensation in the opposite direction. Subsequently, the linear gap segment 433 with large flanging springback helps the linear segment C3 with large flanging springback further have larger rebound compensation in the opposite direction, ensuring that the sheet metal part 1 can more accurately maintain the shape and size required by the design after unloading. This directly improves the quality of the sheet metal part 1. After unloading, the sheet metal part 1 can more accurately maintain the shape and size required by the design, reducing the scrap rate and rework rate caused by springback problems. At the same time, the surface quality and dimensional accuracy of the sheet metal part 1 are also improved. By adjusting the slopes of the linear gap segment 431 with small flanging springback and the linear gap segment 433 with large flanging springback, different stamping conditions and sheet metal part 1 requirements can be flexibly adapted. This design makes the mold more adaptable and flexible when dealing with different materials, thicknesses, and flanging requirements.

[0049] In combination with the first aspect, in one embodiment, Figure 4 and Figure 5 As shown, the flange section gap segment 43 includes a transition straight line gap segment 432, and the transition straight line gap segment 432 is connected between the straight line gap segment 431 with small flange springback and the straight line gap segment 433 with large flange springback. The transition straight line gap segment 432 is parallel to the plane gap segment 41, and the transition straight line gap segment 432 is used to pre-shape the remaining part of the flange section C of the sheet metal part 1 into a pre-shaped transition straight line segment D2 of the flange section D.

[0050] In this embodiment, a transitional linear gap section 432 is newly added to the flange cross-sectional gap section 43. This transitional linear gap section 432 is located between the linear gap section 431 with small flange springback and the linear gap section 433 with large flange springback, serving as a connection and transition. The transitional linear gap section 432 is designed to be parallel to the planar gap section 41. This means that during the stamping process, after the material undergoes initial pre-shaping in the linear gap section 431 with small flange springback, it enters a transition region parallel to the planar gap section 41 and then enters the linear gap section 433 with large flange springback for further shaping. The primary function of the transitional linear gap section 432 is to pre-shape the flange cross-sectional section C of the sheet metal part 1, forming a pre-shaping transitional linear segment D2. The introduction of the transition linear gap section 432 provides a smooth transition zone for sheet metal part 1, allowing the material to flow more smoothly from linear gap section 431 (where the flanging springback is small) into linear gap section 433 (where the flanging springback is large), reducing stress concentration and uneven deformation caused by gap variations. By designing the transition linear gap section 432, the flanging springback of sheet metal part 1 can be more precisely controlled. While linear gap section 431 (where the flanging springback is small) is responsible for initial springback reduction, the transition linear gap section 432 provides a stable transition zone, allowing linear gap section 433 (where the flanging springback is large) to more effectively perform further shaping and springback control. The smooth transition and optimized springback control directly improve the quality of sheet metal part 1. After unloading, sheet metal part 1 can more accurately maintain the required shape and size, reducing scrap and rework rates due to springback issues. The design of the transition linear gap section 432 enhances the mold's adaptability to sheet materials of varying materials and thicknesses, as well as varying flanging requirements. By adjusting the length and gap size of the transition straight line gap section 432 , different stamping conditions and sheet metal part 1 requirements can be flexibly adapted.

[0051] In combination with the first aspect, in one embodiment, Figure 4 As shown, the connection point between one end of the transition straight line gap section 432 and the other end of the flanging rebound small straight line gap section 431 is chamfered.

[0052] In this embodiment, a chamfer is employed at the junction between one end of the transition linear gap segment 432 and the other end of the linear gap segment 431 with low flanging springback. This means that the connection between the two gap segments is not a sudden right-angle transition, but rather a smooth, rounded transition. This design aims to reduce stress concentration and scratches that may occur when the material passes through this junction, ensuring a smoother transition from one gap segment to the other. The chamfer effectively distributes stress generated by the material passing through the junction, preventing deformation or damage caused by stress concentration. This helps maintain the integrity and stability of the material, improving the quality of the sheet metal part 1. The rounded transition reduces the risk of scratches on the material caused by the die. During the stamping process, the material may rub against the die edge, and the rounded corner design reduces this friction, thereby protecting the material's surface quality. The rounded transition reduces wear and damage to the die during the stamping process, thereby extending the die's service life. This reduces production and maintenance costs and improves production efficiency. By reducing stress concentration, preventing scratches, and enhancing die durability, the chamfer can comprehensively improve the forming effect of the sheet metal part 1. After unloading, the sheet metal part 1 can more accurately maintain the shape and size required by the design, and the surface quality and dimensional accuracy are also significantly improved.

[0053] In combination with the first aspect, in one embodiment, Figure 4 As shown, the connection between the other end of the transition straight line gap section 432 and one end of the straight line gap section 433 with large flanging rebound amount is chamfered.

[0054] In this embodiment, a chamfer is also employed at the point where the other end of the transition linear gap section 432 connects to one end of the linear gap section 433 with high flanging springback. This means that when the material is drawn and shaped from the transition linear gap section 432 to the linear gap section 433 with high flanging springback, it undergoes a smooth, rounded transition, rather than an abrupt right-angle turn. Similar to the rounded corner design between the transition linear gap section 432 and the linear gap section 431 with low flanging springback, this rounded corner effectively distributes the stress generated by the material as it passes through the joint, further reducing material deformation or damage caused by stress concentration. The rounded corner transition significantly reduces friction between the material and the die edge as it passes through the joint, thereby preventing scratches and cracks. This is crucial for maintaining material integrity and improving the surface quality of the sheet metal part 1. The rounded corner transition reduces wear and damage to the die during the stamping process, thereby extending the die's service life and reducing production and maintenance costs. By reducing stress concentration, preventing scratches and cracks, and increasing die life, the rounded corner design significantly enhances the overall forming stability of the sheet metal part 1. This enables the sheet metal part 1 to maintain its shape and size more stably after unloading, thereby improving the quality and reliability of the sheet metal part 1 .

[0055] In combination with the first aspect, in one embodiment, Figure 6 As shown, the drawing and flanging die also includes: a flanging punch 5 and a flanging die 6. A reserved groove 51 is provided on the side of the flanging punch 5 facing the flanging die 6. The reserved groove 51 is used to accommodate the pre-shaped transition straight line segment D2 and the pre-shaped flanging large springback straight line segment D3 formed by the sheet metal part 1.

[0056] In this embodiment, the draw-flanging die comprises a flanging punch 5 and a flanging die 6, which are the primary working components of the die, used to flanging the sheet metal part 1. A pre-reserved groove 51 is specifically defined on the side of the flanging punch 5 facing the flanging die 6. The design of this pre-reserved groove 51 is crucial; its shape and dimensions match the pre-shaping transition straight segment D2 and the pre-shaping flanging springback-rich straight segment D3 formed after the pre-shaping of the sheet metal part 1. During the stamping process, when the sheet metal part 1 is fed into the drawing die (drawing punch 2 and drawing die 3), it will pass through the previously described flanging section gap section 43 (including the straight line gap section 431 with small flanging springback, the transition straight line gap section 432 and the straight line gap section 433 with large flanging springback) for pre-shaping. After pre-shaping, the sheet metal part 1 will form a pre-shaping flanging springback small straight line section D1, a pre-shaping transition straight line section D2 and a pre-shaping flanging springback large straight line section D3. Subsequently, when the subsequent flanging die (flanging punch 5 and flanging die 6) are closed, the flanging punch 5 and the flanging die 6 are closed. The die 6 acts together on the rounded corner section B and the straight section C1 with low springback on the sheet metal part 1, while the reserved groove 51 accurately accommodates the pre-shaped transition straight section D2 and the pre-shaped straight section D3 with high springback. The design of the reserved groove 51 makes the flanging process more precise. It ensures that the pre-shaped sheet metal part 1 avoids deformation during the forming process. By accommodating the pre-shaped transition straight section D2 and the pre-shaped straight section D3 with high springback, the reserved groove 51 prevents flanging of the pre-shaped transition straight section D2 and the pre-shaped straight section D3 with high springback.

[0057] In combination with the first aspect, in one embodiment, Figure 5 As shown, the sheet metal part 1 can be the front panel of an automobile. If the maximum rebound amount of the straight section D3 with a large rebound amount of the pre-shaped flange is a, the straight section D3 with a large rebound amount of the pre-shaped flange is rebound compensated in the opposite direction of the rebound direction, and the compensation amount a1 = (1.05~1.1)*a.

[0058] In conjunction with the first aspect, in one embodiment, the width of the pre-shaped flanged section D3 with large springback is determined using finite element analysis (FEA) software. For example, if the flange height of the front dash panel flanged section C is 20.5 mm, the width of the linear gap section 433 with large springback is approximately 12 mm according to finite element analysis (FEA) software analysis. Based on empirical values, the width of the transition linear gap section 432 is within a range of 2 to 3 mm, and its line segment is also horizontal with the sheet metal flat section A. The width of the linear gap section 431 with small springback is 20.5-12-3=5.5 mm, and the angle between the linear gap section 431 with small springback and the horizontal is 10° to 12°. The purpose of setting the linear gap section 431 with small springback at a 10° to 12° angle with the horizontal is to pre-form the material at the flange by stretching, which is beneficial to the freezeability of the part shape after the flanging.

[0059] In combination with the first aspect, in one embodiment, Figure 4 As shown, the fillet R1 between the flange rounded gap section 42 and the straight gap section 431 with small flange rebound can be 1 to 2 mm, the fillet R2 between the straight gap section 431 with small flange rebound and the transition straight gap section 432 can be 5 to 6 mm, and the fillet R3 between the transition straight gap section 432 and the straight gap section with large flange rebound can be 1 to 2 mm.

[0060] In combination with the first aspect, in one embodiment, Figure 6 As shown, the flanging gap between the flanging punch 5 and the flanging die 6 is changed from the original uniform gap (1.0 times the material thickness t) to a variable gap. Starting from the tangent point of the flanging radius section B and ending at the pre-shaping flanging springback linear section D1, the flanging gap is 1.0 times the material thickness. Starting from the pre-shaping transition linear section D2, the flanging gap increases to S, forming a reserved groove 51. This increase in the flanging gap ensures that when the flanging punch 5 reaches the bottom dead center, the pre-shaping transition linear section D2 and the pre-shaping flanging springback linear section D3, which have been drawn to compensate for flanging springback, are not squeezed into a straight edge state by the flanging gap of 1.0 times the material thickness t. Here, after the flanging punch returns and the flanging action is completed, the stress in the pre-shaping transition linear section D2 and the pre-shaping flanging springback linear section D3, which are in the open state, is released, and the pre-shaping transition linear section D2 and the pre-shaping flanging springback linear section D3 rebound to a reasonable range.

[0061] In a second aspect, embodiments of the present application provide a method for controlling the springback of a sheet metal part flanging using the draw flanging die described in some of the above embodiments, comprising the following steps:

[0062] S1: The sheet metal part 1 is drawn using the drawing punch 2 and the drawing die 3. During the drawing process, the flange cross-section segment C of the sheet metal part 1 is pre-shaped into a pre-shaped flange springback small straight line segment D1 using the flange springback small straight line gap segment 431;

[0063] S3: The sheet metal part 1 is punched and flanginged using the flanging punch 5 and the flanging die 6 to complete the drawing and flanging process of the sheet metal part 1 .

[0064] In this embodiment, S1 uses the drawing punch 2 and the drawing die 3 to draw the sheet metal part 1. During the drawing process, the flanging section C of the sheet metal part 1 is pre-shaped by the linear gap segment 431 with small flanging rebound, forming a pre-shaped linear segment D1 with small flanging rebound. The purpose of this step is to preliminarily control the flanging rebound through pre-shaping and to prepare for the subsequent flanging process. S3 uses the flanging punch 5 and the flanging die 6 to stamp and flange the sheet metal part 1. During the stamping process, the reserved groove 51 on the flanging punch 5 will accurately accommodate the remaining part of the sheet metal part 1. Through the close cooperation of the flanging punch 5 and the flanging die 6, the drawing and flanging process of the sheet metal part 1 is completed to form the final flanging shape.

[0065] In conjunction with the second aspect, in one embodiment, before S3, the following steps are included:

[0066] S2: Cutting the stretched area of ​​sheet metal part 1.

[0067] In this embodiment, after the pre-drawing process is complete, step S2 trims the sheet metal part 1, removing unnecessary portions and retaining the area for flanging. Trimming can be performed using a cutting knife on the die or in a separate cutting process to ensure that the trimmed sheet metal part's size and shape meet the requirements of the subsequent flanging process. This step aims to optimize material utilization, reduce unnecessary material waste, and prepare the sheet metal part 1 for a shape suitable for flanging.

[0068] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0069] It should be noted that, in this application, relational terms such as "first" and "second" are used only 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 terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0070] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A drawing and flanging die, characterized in that: It includes: A drawing punch (2) and a drawing die (3), wherein a blanking gap (4) is provided between the drawing punch (2) and the drawing die (3), and the blanking gap (4) comprises a plane gap section (41), a flanged corner gap section (42), and a flanged cross-section gap section (43) that are connected in sequence; The flanging cross-section gap section (43) includes a straight line gap section (431) with a small flanging springback amount, one end of which is connected to the flanging rounded corner gap section (42), and the straight line gap section (431) with a small flanging springback amount extends obliquely from the connection with the flanging rounded corner gap section (42) toward the direction close to the drawing punch (2). The straight line gap section (431) with a small flanging springback amount is used to pre-shape the flanging cross-section section (C) of the sheet metal part (1) into a pre-shaped straight line section (D1) with a small flanging springback amount.

2. The drawing and flanging die according to claim 1, wherein: The connection between one end of the linear gap section (431) with a small amount of flanging rebound and one end of the flanging rounded gap section (42) is arranged in a chamfered manner.

3. The drawing and flanging die according to claim 1, wherein: The flange cross-section gap section (43) comprises a linear gap section (433) with a large flange springback amount, one end of the linear gap section (433) with a large flange springback amount is connected to one end of the linear gap section (431) with a small flange springback amount; The linear gap section (433) with large flanging springback extends obliquely from the connection with the linear gap section (431) with small flanging springback toward the direction close to the drawing punch (2), and the linear gap section (433) with large flanging springback is used to pre-shape another part of the flanging cross-section section (C) of the sheet metal part (1) into a pre-shaped linear segment (D3) with large flanging springback.

4. The drawing and flanging die according to claim 3, wherein: The inclination angle of the linear gap section (431) with a small flanging rebound amount is smaller than the inclination angle of the linear gap section (433) with a large flanging rebound amount.

5. The drawing and flanging die according to claim 3, wherein: The flange cross-sectional gap section (43) further includes a transition straight line gap section (432), wherein the transition straight line gap section (432) is connected between the straight line gap section (431) with a small flange springback amount and the straight line gap section (433) with a large flange springback amount, and the transition straight line gap section (432) is parallel to the plane gap section (41). The transition straight line gap section (432) is used to pre-shape the remaining part of the flange cross-sectional section (C) of the sheet metal part (1) into a pre-shaped transition straight line section (D2).

6. The drawing and flanging die according to claim 5, characterized in that: The connection between one end of the transition straight line gap section (432) and the other end of the flanging small springback straight line gap section (431) is provided with a rounded corner.

7. The drawing and flanging die according to claim 5, wherein: The connection between the other end of the transition straight line gap section (432) and one end of the straight line gap section (433) with large flanging rebound amount is provided with a rounded corner.

8. The drawing and flanging die according to claim 5, wherein: The drawing and flanging die also includes: A flanging punch (5) and a flanging die (6), wherein a reserved groove (51) is provided on a side of the flanging punch (5) facing the flanging die (6), and the reserved groove (51) is used to accommodate a pre-shaped transition straight line segment (D2) and a pre-shaped straight line segment (D3) with a large amount of flanging rebound formed by pre-shaping of the sheet metal part (1).

9. A method for controlling the springback of a sheet metal part flanging using the drawing and flanging die according to claim 8, characterized in that: It includes the following steps: The sheet metal part (1) is drawn using a drawing punch (2) and a drawing die (3). During the drawing process, the flanging cross-section section (C) of the sheet metal part (1) is pre-shaped into a pre-shaped flanging springback small straight line section (D1) using the flanging springback small straight line gap section (431); The sheet metal part (1) is punched and flanging performed using a flanging punch (5) and a flanging die (6), thereby completing the drawing and flanging process of the sheet metal part (1).

10. The method for controlling the springback of a sheet metal part flanging by a drawing flanging die according to claim 9, wherein: Before the sheet metal part (1) is punched and flanging is performed using the flanging punch (5) and the flanging die (6) to complete the drawing and flanging process of the sheet metal part (1), the method further includes: Cutting the stretched area of ​​the sheet metal part (1).

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