A blanking die and blanking process for ultra-thin steel strip

Abstract

The application discloses a blanking die and a blanking process for an ultrathin steel strip, and relates to the technical field of metal precision stamping. The die comprises a punch, a die and a back pressure ejection device arranged in the die. The punch has a center region of a material pressing body and a periphery of a die body, the material pressing surface of the material pressing body has a preset height difference Ah from the blade edge end surface of the die body; and the supporting surface of the back pressure ejection device is flush with the die blade edge plane in the initial state. During blanking, the material pressing body of the punch first contacts the material to be cut and presses the material to be cut on the supporting piece to move downward by a distance Ah, so that the "pre-stretching" is realized before the material is sheared; then, the blade edge of the die body cooperates with the die to complete the blanking. Through the "center pressing and periphery cutting" mode, the stress distribution in the material is effectively improved, the warping deformation is fundamentally inhibited, and the flatness of the material to be cut of the ultrathin steel strip and the cross section quality are significantly improved.

Description

Technical Field

[0001] This application relates to the field of precision metal stamping technology, and in particular to a stamping die and stamping process for ultra-thin steel strip. Background Technology

[0002] In the field of gas compressor valve plates, ultra-thin metal strips with a thickness of <0.1mm are widely used as the main material for stamping. After these parts are stamped, there are high requirements for their flatness. Due to the poor rigidity and weak bending resistance of ultra-thin materials, they are prone to warping, twisting and other flatness defects during the stamping process due to uneven stress distribution, which has become a long-standing technical challenge in the industry.

[0003] In existing technologies, the following solutions are commonly used to improve the flatness of the material to be cut: first, increasing the blank holder force to try to suppress material flow; second, reducing the punch-die clearance; third, improving the sharpness of the cutting edge; and fourth, using a high-strength pressure plate with a toothed blank holder ring. These methods are effective for materials thicker than 0.1 mm, but have little effect on ultra-thin materials of 0.05 mm or less, and may even cause the material to stretch, deform, or be damaged due to excessive pressure. Summary of the Invention

[0004] To improve the flatness of ultra-thin materials after stamping, this application provides a stamping die and stamping process for ultra-thin steel strips.

[0005] Firstly, the punching die for ultra-thin steel strip provided in this application adopts the following technical solution:

[0006] A punching die for ultra-thin steel strip, comprising:

[0007] The punch has a notch at the included angle near the peripheral cutting edge area to form a die body and a blank holder located in the central area of ​​the die body. A height difference Δh = (0.4~0.8)t exists between the blank holder surface and the cutting edge end face of the die body, where t is the thickness of the material to be cut. The area of ​​the blank holder surface is 60%~75% of the projected area of ​​the cutting edge end face of the die body.

[0008] A concave die, used in conjunction with the convex die;

[0009] A back pressure ejection device includes a support member and a support force supply member. The support member is disposed inside the die cavity and connected to the support force supply member. The support surface of the support member is flush with the cutting edge plane of the die cavity.

[0010] A stripper plate is used to clamp the material to be cut before punching.

[0011] The punch and the back pressure ejection device are configured such that, before the peripheral cutting edge area of ​​the die body contacts the material to be cut, the pressure surface cooperates with the support surface to clamp the material to be cut and move the height difference Δh along the punching direction, so that the material to be cut is pre-stretched.

[0012] By adopting the above technical solution, utilizing the height difference Δh between the central area (blank) of the punch and the surrounding cutting edge area, combined with the back pressure ejection device and the stripper plate, before the punching action begins, the blank holder contacts the material to be cut before the cutting edge, and under the action of the back pressure support force, the central area of ​​the material to be cut is pressed first. As the punch continues to descend and punch, this timing difference of "center first, periphery later" makes the material to be cut in a "tightened" or "stretched" state (pre-stretched) radiating outward from the center at the moment of cutting, thereby effectively changing the stress field distribution of ultra-thin materials (especially those with a thickness of 0.05mm and below) during the punching process, avoiding warping and twisting caused by local stress concentration or material flow during traditional flat-bottom punching, and significantly improving the flatness of the material to be cut.

[0013] Optionally, the ratio of the supporting force provided by the supporting surface to the punching force of the material to be cut is greater than or equal to 1.3 times.

[0014] By adopting the above technical solution, the supporting force provided by the supporting surface is set to be greater than or equal to 1.3 times the punching force of the material to be cut. This ensures that the back pressure ejection device can provide sufficient rigid support during the punching process when the punch presses into the material, preventing the material from sinking or deforming irregularly due to insufficient support below. This further improves the stability of the "pre-stretching" effect, allowing the material to be sheared in an extremely stable clamping state.

[0015] Optionally, the support force supply is configured to keep the support force provided by the support surface constant during a single punching process.

[0016] By adopting the above technical solution, the supporting force provided by the support surface is kept constant during a single punching process (especially from the stroke from contact with the material to the completion of the cut), avoiding changes in the material stress state caused by elasticity fluctuations, and further improving the consistency of the flatness of the formed workpiece and the yield rate in mass production.

[0017] Optionally, the blanking gap between the die and the punch is 0.001mm to 0.0015mm.

[0018] By adopting the above technical solution, the punching gap between the die and the punch is controlled within a very small range of 0.001mm to 0.0015mm. For the characteristics of ultra-thin steel strip (such as 0.05mm), combined with the above pre-stretching structure, the cross-sectional quality can be significantly improved, making the proportion of bright band on the punched cross-section exceed 90%, and effectively controlling the burr height below 0.01mm.

[0019] Optionally, the mold body and the pressure body form a stepped punch or a conical punch.

[0020] By adopting the above technical solutions, the mold body and the pressure body form a stepped punch or a conical punch, providing different forms of cutting edge end face implementation. Whether it is a rigid drop of the stepped type or a progressive contact of the conical surface, the aim is to realize the technical concept of the central area contacting and pressing the material before the edge area, which increases the flexibility of mold design to adapt to workpieces of different materials or shapes.

[0021] Optionally, the support member includes a back pressure plate, the side of the back pressure plate facing the punch forming the support surface, and the side of the back pressure plate away from the punch being connected to the support force supply member.

[0022] By adopting the above technical solution, the support component is designed as a back pressure plate, which can provide full-area, continuous and uniform planar support for the material to be cut, minimizing the local micro-deformation of the material during the punching process. It is the preferred structure for achieving high precision flatness.

[0023] Optionally, the support member includes a plurality of densely arranged support pins, the end faces of the plurality of support pins facing the punch forming the support surface, and the ends of the plurality of support pins facing away from the punch being connected to the support force supply member.

[0024] By adopting the above technical solution, the support component uses multiple densely arranged support pins, which can serve as an alternative to the back pressure plate. It is suitable for certain mold scenarios that require specific venting or have limited structures, and can also provide uniform back pressure support in the punching area.

[0025] Secondly, this application discloses a punching process for ultra-thin steel strip, based on the aforementioned punching die for ultra-thin steel strip, comprising the following steps:

[0026] S1. The material to be cut is conveyed between the punch and the die;

[0027] S2. The material to be cut is pressed by the unloading plate and supported by the support member, so that the periphery of the material to be cut is pressed between the unloading plate and the die, and the central area of ​​the material to be cut is supported by the support member.

[0028] S3. Press the material to be cut onto the material using the pressing body to perform pre-stretching;

[0029] S4. Control the movement distance Δh of the punch, and use the peripheral cutting edge area of ​​the die body and the cutting edge plane of the die to punch the material to be cut.

[0030] By adopting the above-mentioned technical solution, namely a punching process for ultra-thin steel strip, the specific process steps of "pressing-pre-stretching-punching" are clearly defined. In particular, steps S3 and S4, by controlling the punch movement distance Δh, precisely realize the stress redistribution of the material before it is cut, thus solidifying the operation process of eliminating internal stress and preventing rebound warping from a process method perspective.

[0031] Optionally, after step S4, the method further includes:

[0032] S5. After blanking, reset the punch and stripper plate, and use the support to eject the blanked workpiece from the cavity of the die.

[0033] By adopting the above technical solution, the workpiece is ejected by the support after punching, realizing an automated unloading process. The ejection action is completed by the back pressure device, which can smoothly send the ultra-thin workpiece out of the die cavity and prevent the workpiece from being deformed by force during the demolding process.

[0034] Optionally, step S4 further includes: keeping the supporting force provided by the supporting surface constant when controlling the punch to move a distance Δh.

[0035] By adopting the above technical solution, the supporting force is kept constant while controlling the punch movement distance Δh, ensuring that the normal clamping force on the material does not decrease or fluctuate during the most critical material shearing deformation stage. This is the key process parameter control to ensure the perpendicularity of the cross-section and the overall flatness of the ultrathin material.

[0036] In summary, this application includes at least one of the following beneficial technical effects:

[0037] 1. Significantly improves the flatness of ultra-thin material punching: Through the synergistic effect of the micro-step design of the punch and the full-area back pressure system, the pre-tension state of "stretching from the center to the outside" is realized in the punching process, which fundamentally solves the industry problem of easy warping when punching ultra-thin stainless steel strips of 0.05mm and below. The flatness can be stably controlled within 0.07mm, greatly improving the yield rate.

[0038] 2. Optimize stress distribution and cross-sectional quality: The specific blanking area ratio and constant high back pressure enable the material to be precisely sheared under extremely small blanking gaps, which not only improves the internal stress distribution, but also results in a high proportion of bright bands and minimal burrs on the blanking cross-section.

[0039] 3. High process stability: By quantitatively designing the support force value, punching clearance and step height, the experience-based debugging is transformed into controllable engineering parameters, ensuring the stability of the mold in high-speed stamping production. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view of the blanking die of Embodiment 1 of this application.

[0041] Figure 2 This is a schematic diagram of Embodiment 1 of this application, mainly showing the punch and the material to be cut.

[0042] Figure 3 This is a cross-sectional view of the blanking die of Embodiment 2 of this application.

[0043] Figure 4 This is a schematic diagram of the ultra-thin steel strip punching process in Embodiment 2 of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 10. Material to be cut; 20. Punch; 201. Peripheral cutting edge area; 202. Cutting edge end face; 21. Mold body; 22. Pressure plate; 221. Pressure plate surface; 30. Stripper plate; 40. Die; 401. Cutting edge plane; 50. Back pressure ejection device; 51. Support component; 511. Back pressure plate; 512. Support surface; 513. Support ejector pin; 514. Bearing plate; 52. Support force supply component. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solution of this application, the following will be described in conjunction with the appendix. Figure 1-4 This application provides a detailed description of the stamping die and stamping process for ultra-thin steel strips disclosed herein. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0047] In the description of this application, some specific terms are explained as follows:

[0048] Ultra-thin stainless steel strip: refers to a strip of stainless steel material with an extremely thin thickness, typically less than 0.1 mm. In the context of this application, it specifically refers to a thickness of 0.05 mm or less, a precision material that, due to its poor rigidity and weak bending resistance, is highly susceptible to warping, twisting, and other flatness defects during conventional stamping processes. The material to be cut in this application refers to materials such as ultra-thin stainless steel strip.

[0049] Blanking force: refers to the maximum force applied by the punch to the material during the blanking process, sufficient to cause it to shear and separate to form a workpiece. The magnitude of this force depends primarily on the shear strength of the material, the material thickness, and the perimeter of the blanked workpiece.

[0050] Pre-stretching: refers to the process of applying tension to a material within the blanking area in a radial pattern, using specific die structures or technological steps, before the material is actually sheared and fractured. This tension effectively improves the stress distribution within the material and is crucial for achieving high-flatness blanking. Example 1

[0051] This embodiment provides a punching die for ultra-thin steel strips, which is particularly suitable for processing ultra-thin stainless steel strips and other materials with a thickness of 0.05mm and below. It aims to solve the problem of flatness defects such as warping and twisting that easily occur after punching ultra-thin materials in the prior art.

[0052] Reference Figure 1 and Figure 2 The blanking die includes an upper die portion and a lower die portion. The upper die portion includes an upper die base, on which a punch fixing plate is provided. A punch 20 and a stripper plate 30 are mounted on the punch fixing plate. The lower die portion includes a lower die base, on which a die 40 is mounted. A back pressure ejection device 50 is provided inside the die 40. The punch 20 and the die 40 cooperate to perform the blanking action. The stripper plate 30 presses the workpiece 10 to be blanked before blanking. The back pressure ejection device 50 provides support force for the workpiece 10 to be blanked. This cooperation allows the workpiece 10 to maintain a good stress state during the blanking process, improving the flatness of the workpiece 10.

[0053] Specifically, a notch is formed around the punch 20 at the included angle near its peripheral cutting edge region 201, so that the punch 20 is structurally divided into a die body 21 and a blank holder 22 located in the bottom center region of the die body 21. The end face of the blank holder 22, i.e. the blank holder surface 221, protrudes a small height difference Δh in the axial direction (i.e., the punching direction) relative to the cutting edge end face 202 of the die body 21, Δh=(0.4~0.8)t, where t is the thickness of the material 10 to be cut.

[0054] In this embodiment, for an ultra-thin stainless steel strip with a thickness of t = 0.05 mm, the height difference Δh is set within the range of (0.4~0.8)t, i.e., Δh = 0.02 mm~0.04 mm. In a preferred embodiment, Δh = 0.6t = 0.03 mm. When Δh is less than 0.4t, the material is cut before entering the plastic tensile stage, and internal stress cannot be eliminated; when Δh is greater than 0.8t, the ultra-thin material is very prone to excessive thinning or even tearing at the cutting edge junction, affecting the strength of the part.

[0055] Meanwhile, in order to achieve effective and uniform pre-stretching of the central area of ​​the material before punching, the area of ​​the pressure surface 221 of the pressure body 22 is set to 60% to 75% of the projected area of ​​the cutting edge end face 202 of the entire punch 20. Preferably, the area ratio is 70%. If the pressure area is less than 60%, the central pressure will be too large and easily cause indentation; if it is greater than 75%, there will be insufficient space for material flow around the cutting edge, resulting in an uneven sheared section. The 60% to 75% design ensures that at the beginning of the punching stroke, the pressure body 22 contacts and presses the material to be cut 10 before the cutting edge of the die body 21, thereby applying a pre-stretching force from the center to the periphery before the material is sheared and broken, effectively improving the stress distribution inside the material, creating ideal stress conditions for subsequent high-precision punching, and thus fundamentally suppressing the occurrence of warping deformation.

[0056] In this embodiment, the die body 21 and the blank holder 22 form a stepped punch, achieving rigid drop punching. In other embodiments, for workpieces with specific shapes, a gently tapered punch (not shown in the figure) is formed between the central blank holder 22 of the punch 20 and the peripheral die body 21. That is, the blank holder surface 221 of the blank holder 22 is a platform with the highest point at the center and gradually decreasing towards the periphery, and its lowest point is connected to the cutting edge end face 202 of the peripheral die body 21. This tapered structure can provide a gentler stress gradient in the pre-stretching stage, and can achieve better flatness control for some stress-sensitive materials or workpieces with complex contours.

[0057] Reference Figure 1 The die 40 has a cutting edge that matches the profile of the die body 21 of the punch 20. The blanking clearance between the die 40 and the punch 20 is preferably set to 0.001mm to 0.0015mm. In one specific embodiment, the blanking clearance is 0.0012mm. This extremely small blanking clearance, combined with pre-stretching, can produce a high-quality blanking cross-section with a very high proportion of bright band (over 90%) and very small burrs (below 0.01mm).

[0058] Optionally, the back pressure ejection device 50 includes a support member 51 and a support force supply member 52. In this embodiment, the support member 51 is specifically an integral back pressure plate 511, the upper surface of which forms a flat support surface 512. In the initial state of the mold, the support surface 512 is strictly flush with the cutting edge plane 401 of the die cavity 40.

[0059] Optionally, the support force supply component 52 employs a device such as a nitrogen spring capable of providing stable pressure, which is connected to the lower surface of the back pressure plate 511 via a push rod. The function of the support force supply component 52 is to provide a uniform and continuous upward support force to the back pressure plate 511 throughout the entire punching process. This support force works in conjunction with the downward pressing force of the stripper plate 30 to securely and flatly clamp the material to be cut 10 between them before the punching begins, forming a "taut" planar stress state.

[0060] Preferably, the ratio of the supporting force provided by the supporting surface 512 to the punching force of the material to be cut 10 is greater than or equal to 1.3 times, which ensures that the back pressure ejection device 50 can provide sufficient rigid support during the punching process when the punch 20 presses the material in, preventing the material from sinking or deforming irregularly due to insufficient support below, and further improving the stability of the "pre-stretching" effect.

[0061] Reference Figure 1 and Figure 2 When the pressing surface 221 and the supporting surface 512 jointly clamp the material to be cut 10 and move it a distance Δh, the material to be cut 10 is punched by the peripheral cutting edge area 201 of the die body 21 and the cutting edge plane 401 of the die 40. During the punching process, due to the setting of the nitrogen spring, the supporting force provided by the supporting surface 512 remains constant during a single punching process, avoiding changes in the material stress state caused by elasticity fluctuations, and further improving the consistency of the flatness of the formed workpiece and the yield rate in mass production.

[0062] The implementation principle of this application embodiment is as follows: First, the material to be cut 10 (e.g., ultra-thin steel strip in coil form) is conveyed to the space between the punch 20 and the die 40 via a feeding device, and is located between the stripper plate 30 and the back pressure plate 511. Subsequently, the upper die descends, and the stripper plate 30 first contacts the material to be cut 10 and applies a pressing force. At the same time, the back pressure plate 511 provides an upward supporting force under the action of the supporting force supply member 52, pressing and leveling the material to be cut 10. The upper die continues to descend, and the central pressing body 22 of the punch 20 contacts the material to be cut 10. Due to the height difference, the pressing body 22 presses the material to be cut 10 together with the back pressure plate 511 below into the cavity of the die 40. During this process, the material to be cut 10 is subjected to strong pressing in the central area of ​​the pressing body 22 and auxiliary pressing by the surrounding stripper plates 30, and the material is pre-stretched from the center outward. When the downward distance of the punch 20 reaches the height difference Δh, the peripheral cutting edge of the punch 20 contacts the pre-stretched material to be cut 10 and cooperates with the cutting edge of the die 40 to complete the precision blanking of the material. After blanking is completed, the upper die returns, and the stripper plate 30 removes the scrap from the punch 20. At the same time, the back pressure plate 511 of the back pressure ejection device 50 resets under the action of the supporting force, smoothly ejecting the blanked workpiece from the cavity of the die 40 to the surface of the die 40, facilitating pickup in subsequent processes.

[0063] Through the synergistic effect of the above structure and process, this embodiment can perform high-precision punching of ultra-thin steel strips with a thickness of 0.05mm, stably controlling the flatness of the workpiece within 0.07mm, and increasing the yield rate from less than 30% to over 95%. Specific test data and results are shown in the table below. Example 2

[0064] This embodiment demonstrates another variant structure of the punching die in Embodiment 1, the main difference being the specific implementation of the support member 51 in the back pressure ejection device 50.

[0065] In some complex-shaped workpiece stamping dies, using a single, integral back pressure plate 511 may present problems such as high processing difficulty, high cost, or difficulty in ensuring flatness due to heat treatment deformation. Therefore, referring to... Figure 3 In this embodiment, the support member 51 is composed of a dense array of multiple (e.g., dozens or hundreds) support pins 513.

[0066] The heads of the support ejector pins 513 are precision ground, and all their end faces facing the punch 20 together form a virtual support surface 512, which is initially flush with the cutting edge plane 401 of the die 40. The tail ends of all the support ejector pins 513 are connected to a support plate 514, which is then connected to the support force supply component 52. By adopting this ejector pin array, it can flexibly adapt to cavities of different shapes of the die 40, and there is a gap between each ejector pin, which is suitable for certain mold scenarios that require specific venting. The support effect it provides is equivalent to that of the integral back pressure plate 511, while having better processability, maintainability and cost advantages. Example 3

[0067] The embodiments of this application also provide an ultra-thin steel strip punching process based on the mold described in any of the above embodiments, referring to... Figure 4 This includes the following steps:

[0068] S1. The material to be cut 10 is conveyed between the punch 20 and the die 40.

[0069] Specifically, the material to be cut 10 is conveyed to the space between the punch 20 and the die 40 by a feeding device.

[0070] S2. The material to be cut 10 is pressed by the unloading plate 30 and supported by the support member 51, so that the periphery of the material to be cut 10 is pressed between the unloading plate 30 and the die 40, and the central area of ​​the material to be cut 10 is supported by the support member 51.

[0071] Specifically, as the upper mold moves downward, the unloading plate 30 first contacts the material to be cut 10 and applies a pressing force. At the same time, the support member 51 provides an upward supporting force under the action of the support force supply member 52, pressing the material to be cut 10 tightly and leveling it.

[0072] S3. The pressing body 22 is used to press the material to be cut 10 for pre-stretching.

[0073] Specifically, the upper die continues to descend, and the blank holder 22 at the center of the punch 20 contacts the material to be cut 10 before the peripheral cutting edges. Utilizing the strong back pressure provided by the support force supply component 52, the blank holder 22 presses down on the material to be cut 10 along with the support component 51 below, moving downwards together. Before the peripheral cutting edges contact the material, the punch 20 moves a distance Δh. During this process, the center of the material is forced to sink, while the outer periphery is pressed down by the stripper plate 30 and restricted by the cutting edge of the die 40, causing tension to be generated from the center outwards within the material, eliminating the original internal stress and wave deformation of the material.

[0074] S4. Control the movement distance Δh of the punch 20, and use the peripheral cutting edge area 201 of the die body 21 and the cutting edge plane 401 of the die 40 to punch the material to be cut 10.

[0075] Specifically, after the punch 20 moves a distance of Δh, the cutting edge of the die 21 contacts the material and cooperates with the die 40 to cut the material. Because the material is in a taut state and the punching clearance is extremely small, the cut is formed instantly, and the perpendicularity of the cut surface is extremely high. During this step, the supporting force remains constant to prevent the material from rebounding at the moment of cutting.

[0076] S5. After blanking, reset the punch 20 and the stripper plate 30, and use the support member 51 to eject the blanked workpiece from the cavity of the die 40.

[0077] Specifically, after blanking is completed, the upper die moves upward and resets. The stripper plate 30 scrapes off the waste strip. At the same time, the support member 51 inside the die cavity 40 resets and springs upward under the action of the supporting force. It not only serves as a base pad during shearing, but also acts as an ejector at this time, smoothly ejecting the blanked workpiece from the cavity of the die cavity 40 to the mold surface, which is convenient for subsequent collection by air blowing or a robot.

[0078] Through the above-mentioned process and mold structure, the flatness of the 0.05mm thick valve plate can be stably controlled within 0.07mm, and the burr height is less than 0.01mm, which significantly improves the product yield.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A punching process for ultra-thin steel strip, comprising a punching die for ultra-thin steel strip, characterized in that, The thickness of the ultra-thin steel strip is 0.05 mm or less, and the punching die includes: A punch (20) has a notch at the angle near the peripheral cutting edge area (201) to form a mold body (21) and a pressure body (22) located in the central area of ​​the mold body (21). The pressure surface (221) of the pressure body (22) and the cutting edge end face (202) of the mold body (21) have a height difference Δh=(0.4~0.8)t, where t is the thickness of the material to be cut (10). The area of ​​the pressure surface (221) of the pressure body (22) is 60%~75% of the projected area of ​​the cutting edge end face (202) of the mold body (21). The concave die (40) is used in conjunction with the convex die (20); The back pressure ejection device (50) includes a support member (51) and a support force supply member (52). The support member (51) is disposed in the die cavity (40) and connected to the support force supply member (52). The support surface (512) of the support member (51) is flush with the cutting edge plane (401) of the die cavity (40). The unloading plate (30) is used to press the material to be cut (10) before punching. The punch (20) and the back pressure ejection device (50) are configured such that, before the peripheral cutting edge region (201) of the die body (21) contacts the material to be cut (10), the pressing surface (221) cooperates with the support surface (512) to clamp the material to be cut (10) and move the height difference Δh along the punching direction, so that the material to be cut (10) is pre-stretched; The ratio of the supporting force provided by the supporting surface (512) to the punching force of the material to be cut (10) is greater than or equal to 1.3 times; The punching gap between the die (40) and the punch (20) is 0.001mm to 0.0015mm; The punching process includes the following steps: S1. The material to be cut (10) is conveyed between the punch (20) and the die (40); S2. The material to be cut (10) is pressed by the unloading plate (30) and supported by the support member (51), so that the periphery of the material to be cut (10) is pressed between the unloading plate (30) and the die (40), and the central area of ​​the material to be cut (10) is supported by the support member (51). S3. Press the material to be cut (10) with the pressing body (22) to perform pre-stretching; S4. Control the movement distance Δh of the punch (20) and use the peripheral cutting edge area (201) of the die body (21) and the cutting edge plane (401) of the die (40) to punch the material to be cut (10). S5. After blanking, reset the punch (20) and the stripper plate (30), and use the support member (51) to eject the blanked workpiece from the cavity of the die (40); Step S4 further includes: keeping the supporting force provided by the supporting surface (512) constant when the punch (20) moves a distance Δh.

2. The punching process for ultra-thin steel strip according to claim 1, characterized in that: The support force supply (52) is configured to keep the support force provided by the support surface (512) constant during a single punching process.

3. The punching process for ultra-thin steel strip according to claim 1, characterized in that: The mold body (21) and the pressure body (22) form a stepped punch (20) or a conical punch (20).

4. The punching process for ultra-thin steel strip according to claim 1, characterized in that: The support member (51) includes a back pressure plate (511), the back pressure plate (511) forming the support surface (512) on the side facing the punch (20), and the side of the back pressure plate (511) away from the punch (20) connected to the support force supply member (52).

5. The punching process for ultra-thin steel strip according to claim 1, characterized in that: The support member (51) includes a plurality of densely arranged support pins (513), the end faces of the plurality of support pins (513) facing the punch (20) form the support surface (512), and the end of the plurality of support pins (513) away from the punch (20) is connected to the support force supply member (52).

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