Adaptive stamping forming die and forming method for automobile parts

Abstract

The application discloses a kind of self-adapting stamping forming die and forming method of automobile parts, die includes lower die seat, upper die seat, guide pillar guide bush, male die, female die, and elastic self-adapting blank holder assembly and springback compensation assembly.Blank holder assembly can automatically adjust blanking gap and blanking force with plate thickness by the cooperation of inclined pressure surface and elastic blank holder ring;Springback compensation assembly forms reverse pre-deformation surface by floating compensation punch on the bottom of male die during stamping, offsets the natural springback of plate after die opening.The forming method includes five steps of plate positioning, self-adapting blanking, pre-deformation stamping, pressure maintaining and shaping, and die opening and taking out.The application adopts pure mechanical structure, without additional electric control components, can adapt to stamping of automobile parts of different thickness and different material, reduce the wrinkling and cracking failure rate, improve the size accuracy and batch consistency of parts, reduce the workload of manual die repair, and is suitable for stamping production of automobile structural parts and cover parts.

Description

Technical Field

[0001] This invention relates to the field of automotive stamping die technology, specifically to an adaptive stamping die and forming method for automotive parts. Background Technology

[0002] Automotive body panels and structural components are mostly formed using cold stamping processes. The surface contour quality and dimensional accuracy of these parts directly affect the assembly accuracy and appearance consistency of the entire vehicle. Conventional stamping dies employ a rigid, fixed surface structure, pressing the sheet metal with a preset fixed blank holder force to induce plastic deformation and obtain the target shape.

[0003] In actual mass production, the thickness tolerance of raw material plates varies within the limits allowed by national standards, and the mechanical properties such as yield strength and elongation of materials from different steel mills and different batches are discrete. At the same time, after the plate is stamped and unloaded, the release of internal residual stress will produce elastic rebound, causing the part dimensions to deviate from the design value.

[0004] The existing stamping dies and processes have two core defects: First, the blank holder structure is rigidly fixed, and the blank holder force mostly relies on the external air cushion for uniform setting. It is impossible to dynamically adjust the blank holder gap and blank holder force according to the actual thickness of a single sheet of material. When the material thickness is too thin, excessive blank holder force can easily cause tearing, and when the material thickness is too thick, insufficient blank holder force can easily cause wrinkling. The overall stamping defect rate has remained high for a long time. Second, springback compensation mainly relies on manual die repair and surface grinding in the later stage. It is a post-correction and cannot actively and adaptively offset springback during the stamping process. The debugging cycle is long, the die repair workload is large, and the dimensional consistency of multiple batches of production is poor.

[0005] To address the aforementioned issues, some existing technologies have attempted to improve stamping quality by incorporating elastic blank holder structures or springback compensation structures. For example, Chinese patent document CN109365639B discloses a deep-drawing die with an adjustable constant-force elastic blank holder mechanism. This mechanism achieves constant control of the blank holder force through the cooperation of a rotating pressure plate and a position-maintaining structure. However, the blank holder force adjustment in this solution relies on a complex gear-rack transmission mechanism, resulting in a complex structure and the blank holder force adjustment range being limited by the deformation stroke of the elastic holding member, making it difficult to adapt to the dynamic changes in sheet thickness. Another example is Chinese patent document CN108672562B, which discloses a side-wall forming die. This die achieves sequential pressing of the blank holder ring by setting the length difference between inner and outer secondary ejector pins to reduce the drawing depth of the side-wall opening. However, the blank holder ring in this solution is still a fixed-stroke structure and cannot be adaptively adjusted in real time according to fluctuations in sheet thickness.

[0006] Regarding springback compensation, Chinese patent document CN101164715B discloses an asymmetric stretch forming die that induces sheet metal springback. This die uses an asymmetric punch structure to induce springback for measurement purposes. However, this die is only used for inducing and measuring springback and does not provide a technical means for actively compensating for springback during the stamping process. Chinese patent document CN105251845B discloses a forming device for a strength plate. It uses floating blocks to achieve bidirectional force on the sheet metal to reduce springback. However, the floating blocks in this solution can only provide auxiliary force in the edge area of ​​the sheet metal and cannot achieve precise springback compensation in the critical area of ​​the punch forming surface.

[0007] In addition, although there are existing technologies that use CAE simulation to predict springback and perform reverse compensation on the mold surface, they all fall under the category of offline compensation. The compensation amount needs to be determined through repeated iterative calculations before mold processing. They cannot be adaptively adjusted in real time according to the actual working conditions during the stamping process, and the cost of changeover and debugging is high, making it difficult to adapt to the production needs of the automotive industry for multiple varieties and small batches. Summary of the Invention

[0008] This invention addresses the shortcomings of existing technologies by solving the problems that stamping dies cannot adapt to material thickness fluctuations, the blank holder force cannot be dynamically adjusted, and springback compensation relies on manual die repair afterward. It provides a stamping die and matching forming method that combines adaptive blank holder force and dynamic springback compensation. Under a purely mechanical structural framework, it achieves self-adaptation of blank holder force and active springback compensation, thereby reducing stamping defect rate and improving part dimensional accuracy and production changeover efficiency.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides an adaptive stamping die for automotive parts, including a lower die base, a die fixing plate, a die, a guide post, an upper die base, a guide sleeve, a punch fixing plate, a punch, and an elastic adaptive blank holder assembly and a springback compensation assembly. The die fixing plate is fastened to the top of the lower die base by bolts, and the die is fixedly installed at the center of the die fixing plate by a locating pin; the guide post is vertically fixed to the top corner of the lower die base, and the guide sleeve is fixed to the upper die base and slides with the guide post to form a die closing guide pair; the punch fixing plate is fixed to the bottom of the upper die base, and the punch is fastened to the lower end face of the punch fixing plate and aligned vertically with the die.

[0010] The elastic adaptive pressing assembly includes a pressing ring and a pressing spring. An annular groove is formed on the top of the die fixing plate on the outer side of the die. The pressing ring is embedded in the groove and can slide vertically up and down. The pressing spring is positioned between the bottom of the pressing ring and the bottom of the groove, providing upward elastic support for the pressing ring. The top of the pressing ring is machined with an outwardly and downwardly extending inclined pressing surface. When the sheet material is pressed down, the inclined surface decomposes the vertical force, driving the pressing ring to compress the spring and achieve adaptive adjustment.

[0011] The springback compensation assembly includes a floating compensation mandrel and a compensation spring. A blind hole is provided on the bottom end face of the punch. The floating compensation mandrel is assembled in the blind hole and can slide along the axial direction. The compensation spring is located between the bottom of the blind hole and the top of the floating compensation mandrel. In its natural state, the mandrel is pushed outward. When under pressure, the mandrel retracts to form a reverse pre-deformation surface.

[0012] Furthermore, the guide sleeves are fixed at the four corners of the upper mold base, corresponding one-to-one with the guide pillars, to ensure the verticality of the mold closing and prevent uneven loading and jamming.

[0013] Furthermore, multiple pressure springs are provided, evenly distributed along the bottom circumference of the pressure ring to ensure consistent circumferential pressure force and prevent the sheet material from tilting.

[0014] Furthermore, multiple blind holes are provided and distributed circumferentially along the convex mold surface; for irregular curved surface convex molds, blind holes are preferentially arranged in areas prone to springback where curvature changes abruptly and stress concentrates after mold opening.

[0015] Furthermore, the number of floating compensation mandrels and blind holes are the same and they slide in a one-to-one correspondence, with the clearance controlled at 0.02~0.05mm; the compensation spring is coaxially set with the blind hole to avoid uneven wear of the spring.

[0016] Furthermore, the groove is formed by milling the top surface of the die fixing plate vertically downwards, and the groove wall is precision machined to ensure straightness and roughness.

[0017] On the other hand, the present invention provides an adaptive stamping forming method for automotive parts, implemented using the above-mentioned mold, comprising the following steps: (a) Sheet material loading and positioning: The cut sheet metal to be stamped is transferred to the die cavity by a robotic arm or manually. The edge of the sheet metal naturally rests on the inclined pressure surface at the top of the pressure ring, and the initial positioning is automatically centered by relying on the inclined guide.

[0018] (ii) Adaptive edge clamping adjustment: The press drives the upper die base downward. Before the punch contacts the plate, the plate is pressed down and tilted with the upper die pressing action. This decomposes into a vertically downward component force that pushes the pressure ring down along the slide groove to compress the pressure spring. The compression amount of the pressure spring changes automatically with the actual thickness of the plate, and the pressure gap and the pressure force are adjusted synchronously.

[0019] (III) Pre-deformation stamping: As the upper mold base continues to descend, the floating compensation mandrel first contacts the upper surface of the sheet metal. As the mold closing pressure gradually increases, the floating compensation mandrel overcomes the supporting force of the compensation spring and retracts into the blind hole, causing the bottom of the punch to form a pre-deformed surface that is opposite to the springback trend of the sheet metal. When the mold is closed to the bottom dead center, the sheet metal is completely molded and shaped.

[0020] (iv) Pressure holding and shaping: After the mold closes and reaches the bottom dead center, the pressure holding time is set to allow the plastic deformation inside the sheet to develop fully and reduce the peak value of residual stress.

[0021] (v) Mold opening and part removal: After the pressure holding period ends, the press drives the upper die holder to move upward to release the pressure. The residual stress inside the sheet metal is released, resulting in natural springback. The amount of springback deformation cancels out the amount of pre-deformation formed during the stamping stage, ultimately yielding a molded part with dimensions that meet the design requirements.

[0022] Furthermore, in step (ii), the compression of the edge spring is positively correlated with the thickness of the sheet material. For every 0.1 mm increase in sheet material thickness, the edge spring is compressed by 0.08~0.12 mm. The edge pressing force increases linearly with the compression, ensuring that the edge pressing force is within a reasonable range for different material thicknesses.

[0023] Furthermore, in step (iii), based on the material and thickness of the plate and the target springback amount obtained from CAE simulation, a compensation spring with corresponding stiffness is pre-selected so that the maximum retraction of the floating compensation head is 1.05 to 1.15 times the target springback compensation amount, thus offsetting the influence of residual deformation during pressure holding.

[0024] Furthermore, in step (iii), for the easily springback areas of irregularly shaped parts, by selecting compensation springs with different stiffnesses, the retraction amount of the floating compensation head at the corresponding position is greater than that in ordinary areas, thereby achieving differentiated local pre-deformation compensation.

[0025] The beneficial effects of this invention are as follows: 1. Adaptive matching of blank holder force reduces stamping defect rate. Through a purely mechanical structure of inclined blank holder surface and elastic blank holder ring, without the need for additional electronic control components, the blank holder gap and blank holder force can be automatically adjusted according to the actual thickness of the sheet metal. When the material thickness increases, the blank holder force increases synchronously, and when the material thickness decreases, the blank holder force automatically decreases, effectively balancing the boundary between tearing and wrinkling, and significantly reducing the stamping defect rate.

[0026] 2. Active springback compensation improves dimensional accuracy and consistency. Through the elastic floating compensation head at the bottom of the punch, a reverse pre-deformation surface is actively constructed during the stamping die closing stage. After the die opens and the force is released, the sheet metal naturally springs back, precisely offsetting the pre-deformation. This active compensation during the process eliminates the need for manual die repair afterward, significantly improving part dimensional accuracy and batch consistency.

[0027] 3. High changeover efficiency and low modification cost. The mold itself has the ability to adapt to different material thicknesses. When changing molds for different thicknesses of the same series of plates, there is no need to adjust the external air cushion pressure and mold clearance. Only the compensation spring needs to be replaced as needed to adapt, which greatly shortens the changeover and debugging cycle. All of them adopt a mechanical elastic structure, which can be directly adapted to existing conventional stamping equipment. The old mold is easy to modify and easy to promote and apply.

[0028] 4. Differentiated compensation adapts to complex surfaces. For the easily springback areas of irregularly shaped parts, compensation mandrels can be independently arranged and corresponding stiffness springs can be selected to achieve precise local compensation. Compared with the compensation method of overall surface mold modification, it is more flexible and more targeted, and adapts to the molding requirements of complex automotive body panels and structural parts. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of the overall structure of the stamping die of the present invention; Figure 2 This is a top view of the assembly structure of the upper mold base and the guide sleeve; Figure 3 This is a schematic diagram of the structure of the punch fixing plate and the bottom end face of the punch; Figure 4 This is a schematic diagram of the assembly structure of the die fixing plate and the elastic adaptive pressing edge assembly; Figure 5 This is a partial cross-sectional structural diagram of the blind hole at the bottom of the punch and the springback compensation component; Figure 6 This is a schematic diagram of the three-dimensional structure of the pressure ring.

[0030] Figure label: 1. Lower die holder; 2. Upper die holder; 3. Guide sleeve; 4. Guide post; 5. Punch fixing plate; 6. Die fixing plate; 7. Punch; 8. Elastic adaptive blank holder assembly; 801. Blank holder ring; 802. Slide groove; 803. Blank holder spring; 804. Blank holder surface; 9. Springback compensation assembly; 901. Floating compensation mandrel; 902. Compensation spring; 903. Blind hole. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0032] Example 1: Mold Structure Implementation like Figures 1 to 6 As shown, the adaptive stamping die for automotive parts provided in this embodiment is used for stamping automotive door sill reinforcement parts. The whole adopts a rear guide pillar die frame structure, including a lower die base 1, an upper die base 2, a guide assembly, a forming assembly, an elastic adaptive pressure edge assembly 8, and a springback compensation assembly 9.

[0033] The lower mold base 1 is made of HT300 cast steel and serves as the support base for the bottom of the mold. The top surface is precision machined to form an installation reference surface. The cavity mold fixing plate 6 is fastened to the center of the top of the lower mold base 1 by internal hex bolts. The cavity mold is positioned by cylindrical pins and fastened to the center area of ​​the cavity mold fixing plate 6 by bolts. The surface of the cavity mold matches the outer contour of the sill reinforcement.

[0034] The guiding assembly includes four guide pillars 4 and four guide sleeves 3. The four guide pillars 4 are vertically fixed at the four corners of the top of the lower mold base 1 with an interference fit. The four guide sleeves 3 are correspondingly interference-fitted into the mounting holes at the four corners of the upper mold base 2. The inner wall of the guide sleeve 3 slides with the outer wall of the guide pillar 4 with a fitting accuracy of H7 / h6, ensuring the verticality of the upper mold base 2's vertical movement and preventing horizontal offset and off-center loading jamming during mold closing.

[0035] The bottom of the upper mold base 2 is fastened to the punch fixing plate 5 by bolts. The punch 7 is fixed to the bottom center of the punch fixing plate 5 by positioning pins and bolts. The profile of the punch 7 matches the inner contour of the sill reinforcement and is aligned with the die. When the mold is closed, they together form the forming cavity.

[0036] The elastic adaptive blank holder assembly 8 is mounted on the die fixing plate 6 and arranged in a ring around the outer side of the die. It includes a blank holder ring 801, an annular groove 802, and 16 blank holder springs 803. The groove 802 is formed by milling vertically downward from the top surface of the die fixing plate 6, and the groove wall is ground to ensure straightness and surface roughness. The blank holder ring 801 is an integral annular structure made of Cr12MoV material and is embedded in the groove 802. It can slide up and down along the vertical direction of the groove 802 with a sliding stroke of 8mm.

[0037] Sixteen pressure springs 803 are evenly arranged circumferentially between the bottom of the pressure ring 801 and the bottom of the groove 802. The two ends of each spring are welded and fixed to the bottom surface of the pressure ring 801 and the bottom of the groove 802, respectively, providing upward elastic support for the pressure ring 801. A pressure surface 804 is machined around the top of the pressure ring 801. The pressure surface 804 is an outwardly and downwardly inclined surface with an inclination angle of 20°. When the edge of the sheet material is placed on the pressure surface 804, the downward pressure force can be decomposed into a horizontal component and a vertical component. The vertical component pushes the pressure ring 801 downward to compress the springs, automatically adapting to sheets of different thicknesses.

[0038] The springback compensation component 9 is mounted on the punch 7 and includes 12 floating compensation heads 901, 12 blind holes 903, and 12 compensation springs 902. The 12 blind holes 903 are opened on the bottom end face of the punch 7 and are distributed circumferentially along the profile contour; among them, 8 are arranged in the easily springback areas where the curvature of the sill piece changes abruptly at both ends, and 4 are arranged in the straight areas to achieve a differentiated compensation layout.

[0039] Each blind hole 903 is fitted with a corresponding compensating spring 902 and a floating compensating head 901. The top end of the compensating spring 902 is welded and fixed to the bottom of the blind hole 903, and the bottom end is welded and fixed to the top end of the floating compensating head 901. The side wall of the floating compensating head 901 slides with a small clearance of 0.03mm with the inner wall of the blind hole 903, allowing for smooth expansion and contraction along the axial direction of the blind hole 903. In its natural state, the compensating spring 902 pushes the floating compensating head 901 outward, with the end face of the head protruding 0.6mm beyond the reference surface of the punch 7. When under pressure, the floating compensating head 901 retracts inward, forming a concave pre-deformation surface on the punch surface to counteract the springback of the sheet metal after mold opening.

[0040] Example 2: Stamping Forming Method of DC04 Cold-Rolled Steel Sheet This embodiment uses the mold described in Embodiment 1 to stamp automotive door sill reinforcement parts made of DC04 cold-rolled steel sheet. The nominal thickness of the sheet is 1.5mm. The specific process steps are as follows: (a) Plate feeding and positioning: The cut square plate is transferred to the top of the die by a two-dimensional robot. The edge of the plate is naturally placed on the inclined pressing surface 804 on the top of the pressing ring 801. Automatic centering is completed by the self-guiding effect of the 20° inclined surface, without the need for additional positioning pins.

[0041] (II) Adaptive Edge Press Adjustment: The press slide drives the upper die holder 2 to descend at a speed of 150 mm / s. Before the punch 7 contacts the sheet metal, the upper die's pressure plate first presses down on the edge of the sheet metal, causing the sheet metal to apply positive pressure to the inclined pressure surface 804. This results in a vertically downward component force that pushes the edge press ring 801 to move downwards along the slide groove 802. The measured average thickness of the sheet metal in this batch is 1.52 mm. The edge press spring 803 is compressed by 0.24 mm accordingly, and the edge press force is automatically increased to a value suitable for the 1.52 mm material thickness. No manual adjustment of the air cushion pressure parameters is required throughout the process.

[0042] (III) Pre-deformation stamping: As the upper die holder 2 continues to descend, the floating compensation mandrel 901 first contacts the upper surface of the sheet metal. As the die closing pressure gradually increases, the floating compensation mandrel 901 gradually compresses the compensation spring 902 and retracts into the blind hole 903. The compensation spring stiffness is greater in the easily rebounding areas at both ends, with a maximum mandrel retraction of 0.55mm; the spring stiffness is smaller in the straight areas, with a maximum mandrel retraction of 0.3mm, forming differentiated pre-deformation surfaces. When the die is closed to the bottom dead center, the sheet metal is completely attached to the convex and concave die surfaces, completing the plastic forming.

[0043] (iv) Holding pressure and shaping: After the mold reaches the bottom dead center, hold pressure for 3 seconds to allow the plastic deformation inside the sheet to develop fully, release some residual stress, and reduce the total springback after the mold is opened.

[0044] (V) Mold Opening and Part Removal: After the pressure holding period, the press slide moves the upper mold base 2 upward to release pressure, and the residual stress inside the sheet metal is gradually released, resulting in natural springback. Testing shows that the average springback of this batch of sheet metal is approximately 0.51mm, which offsets the pre-deformation indentation formed during the stamping stage. The dimensional deviation of the key inspection points of the final part is controlled within 0.12mm, meeting the tolerance requirements of the product drawings. Removing the part completes one stamping cycle.

[0045] Example 3: Stamping Forming Method for 5052 Aluminum Alloy Sheets The difference between this embodiment and Embodiment 2 is that the sheet material to be stamped is a 5052 aluminum alloy sheet with a thickness of 1.0mm. This material has a large springback and is widely used in lightweight automotive body panels.

[0046] In step (ii), because the aluminum alloy sheet is relatively thin, the vertical pressure applied by the edge of the sheet to the pressing surface 804 is small. The compression of the pressing spring 803 is 2.8mm, corresponding to a pressing force of 112kN. This pressing force can ensure the pressing effect of the sheet edge without causing the aluminum alloy sheet to crack due to excessive pressing force.

[0047] In step (iii), considering the springback characteristics of 5052 aluminum alloy (the free springback amount measured in the preliminary experiment is about 2.8mm), a compensation spring 902 with an elastic coefficient of 40N / mm is selected so that the maximum retraction of the floating compensation head 901 during mold closing reaches 3.0mm, forming a pre-deformation surface with a pre-deformation amount of 3.0mm at the bottom of the punch 7.

[0048] In step (5), after stamping, the natural springback of the sheet metal (2.8 mm) and the pre-deformation of the pre-deformed surface (3.0 mm) cancel each other out, and the dimensional deviation of the final formed part is controlled within 0.28 mm, which meets the dimensional tolerance requirements of aluminum alloy cover parts.

[0049] Example 4: Stamping Forming Method of QP980 Ultra-High Strength Steel Plate The difference between this embodiment and Embodiment 2 is that the sheet material to be stamped is QP980 ultra-high strength steel plate with a thickness of 1.0mm. This material has high yield strength and is widely used in safety structural components such as automobile B-pillars.

[0050] In step (ii), due to the high yield strength of QP980 steel plate, the reaction force of the plate on the blank holder 801 during the stamping process is relatively large. In this embodiment, the blank holder spring 803 is made of high-strength spring steel, with a compression amount of 2.5mm when the plate thickness is 1.0mm, providing a blank holder force of approximately 130kN, effectively controlling the risk of wrinkling and cracking of the high-strength steel plate during the drawing process.

[0051] In step (iii), considering the springback characteristics of QP980 steel plate (the springback amount measured in the preliminary experiment is about 1.2mm), a compensation spring 902 with an elastic coefficient of 70N / mm is selected to make the retraction amount of the floating compensation head 901 reach 1.5mm, forming a pre-deformation surface with a pre-deformation amount of 1.5mm at the bottom of the punch 7.

[0052] In step (5), after stamping, the natural springback of the sheet metal (1.2mm) and the pre-deformation of the pre-deformed surface (1.5mm) cancel each other out, and the dimensional deviation of the final formed part is controlled within 0.2mm. In a batch experiment of 100 pieces of continuous stamping, the fluctuation range of dimensional deviation was only ±0.15mm, and the production consistency was excellent.

[0053] Comparative test verification To quantify and verify the technical effects of the present invention, a control experiment was set up for production testing. The test data can directly support the inventiveness and practicality of the present invention.

[0054] 1. Test conditions 2. Test materials: Three types of sheet metal commonly used in the automotive industry were selected: DC04 cold-rolled steel sheet (1.5mm), 5052 aluminum alloy sheet (1.0mm), and QP980 high-strength steel sheet (1.0mm). Fifty samples of each specification were prepared.

[0055] 3. Control group: A traditional rigid blank holder die with the same shape was used. The blank holder force was set as a fixed air cushion pressure according to the nominal material thickness. There was no springback compensation structure on the shape.

[0056] 4. Experimental group: The mold and corresponding molding method described in Example 1 of this invention are used.

[0057] 5. Inspection indicators: average springback of key surfaces, standard deviation of springback, wrinkling defect rate, cracking defect rate, dimensional qualification rate, and average number of mold repairs per 100 parts.

[0058] Test results Results Analysis The experimental data show that: The adaptive edge-pressing structure of the present invention effectively adapts to plates of different thicknesses and materials, and the edge-pressing force is automatically matched to a reasonable range, which solves the industry contradiction of thin material tearing and thick material wrinkling, and reduces the overall stamping defect rate by an order of magnitude. The floating springback compensation structure actively pre-deforms to offset more than 80% of the sheet springback, significantly improving dimensional accuracy and batch consistency, and eliminating the need for repeated manual mold repair and adjustment. The time required for model changeover and debugging is greatly reduced. For plates of different materials and thicknesses in the same series, only the corresponding stiffness compensation spring needs to be replaced to complete the adaptation. There is no need to repair the entire mold, which can meet the production needs of the automotive industry for multiple varieties and small batches.

[0059] In summary, this invention achieves adaptive pressure and active springback compensation through a purely mechanical structure. Compared with existing rigid molds and fixed processes, it has outstanding substantive features and significant progress, and meets the inventiveness requirements of the Patent Law.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adaptive stamping die for automotive parts, comprising a lower die base (1), a die fixing plate (6) fixedly connected to the top of the lower die base (1), a die fixedly installed on the die fixing plate (6), a guide post (4) fixedly connected to the top of the lower die base (1), a guide sleeve (3) fixedly connected to the upper die base (2) and slidingly engaged with the guide post (4), a punch fixing plate (5) fixedly connected to the bottom of the upper die base (2), and a punch (7) fixedly connected to the punch fixing plate (5); Its features are, An elastic adaptive pressing component (8) is provided on the concave die fixing plate (6), and a springback compensation component (9) is provided on the convex die fixing plate (5). The elastic adaptive pressing component (8) includes a pressing ring (801) and a pressing spring (803). The top of the die fixing plate (6) is provided with an annular groove (802) located on the outside of the die. The pressing ring (801) is slidably connected to the die fixing plate (6) in the vertical direction through the groove (802). The pressing spring (803) is located between the bottom of the pressing ring (801) and the bottom of the groove (802). The top of the pressing ring (801) is provided with a pressing surface (804), which is an inclined surface extending outward and downward. The springback compensation assembly (9) includes a floating compensation head (901) and a compensation spring (902). A blind hole (903) is provided at the bottom of the punch (7). The floating compensation head (901) is slidably connected to the punch (7) in the vertical direction through the blind hole (903). The compensation spring (902) is disposed between the bottom of the blind hole (903) and the top of the floating compensation head (901).

2. The adaptive stamping die for automotive parts according to claim 1, characterized in that, The guide sleeve (3) is fixedly connected to the four corners of the upper mold base (2) and is set one-to-one with the guide post (4).

3. The adaptive stamping die for automotive parts according to claim 1, characterized in that, Multiple pressure springs (803) are provided, and the multiple pressure springs (803) are evenly distributed circumferentially at the bottom of the pressure ring (801). The inclination angle of the pressure surface (804) is 15°~25°.

4. The adaptive stamping die for automotive parts according to claim 1, characterized in that, Multiple blind holes (903) are provided, and the multiple blind holes (903) are distributed circumferentially along the profile at the bottom of the punch (7).

5. The punch (7) is an irregularly shaped punch, and multiple blind holes (903) are distributed and opened corresponding to the springback area of ​​the irregularly shaped punch. The number of floating compensation mandrels (901) and blind holes (903) are the same and they slide in a one-to-one correspondence, with a clearance of 0.02~0.05mm.

6. The number of the compensation springs (902) and the number of the blind holes (903) are the same and they are coaxially arranged.

7. The adaptive stamping die for automotive parts according to claim 1, characterized in that, The groove (802) is formed by a vertical downward recess of the top surface of the die fixing plate (6), and the groove wall is ground.

8. An adaptive stamping forming method for automotive parts, characterized in that, The adaptive stamping die according to any one of claims 1-5 includes the following steps: (a) Plate feeding and positioning: The plate to be stamped is moved to the top of the die, and the edge of the plate is placed on the inclined pressure surface (804) on the top of the pressure ring (801). Automatic centering and initial positioning are completed by relying on the inclined surface guide. (ii) Adaptive edge pressing adjustment: Drive the upper mold base (2) downward, and the edge of the plate presses down the inclined pressing surface (804) with the mold closing action, generating a vertical component force to push the pressing ring (801) downward along the slide groove (802) to compress the pressing spring (803), and automatically adjust the pressing gap and pressing force according to the actual thickness of the plate; (III) Pre-deformation stamping: The upper die holder (2) continues to descend, and the floating compensation head (901) contacts the upper surface of the sheet first; as the die closing pressure increases, the floating compensation head (901) overcomes the supporting force of the compensation spring (902) and retracts inward along the blind hole (903), so that the bottom of the punch (7) forms a pre-deformation surface opposite to the springback trend of the sheet, until the die closes to the bottom dead center, and the sheet stamping is completed; (iv) Holding pressure and shaping: After the mold is closed to the bottom dead center, hold the pressure for 2~5 seconds to allow the plastic deformation of the sheet to develop fully and reduce the peak value of residual stress; (v) Opening the mold and taking out the parts: Drive the upper mold base (2) to move upward to relieve pressure. The residual stress of the plate is released and natural springback is generated. The springback amount is offset by the pre-deformation amount of the pre-deformed surface. After obtaining the molded part, take it out.

9. The adaptive stamping forming method for automotive parts according to claim 6, characterized in that, In step (ii), the compression of the edge spring (803) is positively correlated with the thickness of the sheet. For every 0.1 mm increase in sheet thickness, the edge spring (803) is compressed by 0.08~0.12 mm, and the edge force increases linearly with the compression.

10. The adaptive stamping forming method for automotive parts according to claim 7, characterized in that, In step (iii), based on the material, thickness and target springback of the sheet metal to be stamped, a matching compensation spring (902) with corresponding stiffness is pre-selected so that the maximum retraction of the floating compensation head (901) is 1.05 to 1.15 times the target springback compensation amount.

11. The adaptive stamping forming method for automotive parts according to claim 8, characterized in that, In step (iii), for the springback area of ​​the irregular punch, the shrinkage of the floating compensation head (901) at the corresponding position is greater than that of the normal area, forming a differentiated local pre-deformation.

12. The adaptive stamping forming method for automotive parts according to claim 9, characterized in that, In step (5), after the natural springback of the sheet metal is offset by the pre-deformation, the dimensional deviation of the key surfaces of the part is controlled within ±0.3mm.

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