A method for stamping a locally varying cross-section part and a stamping die

Abstract

The application relates to a local variable cross-section part stamping method and a stamping die, which comprises the following steps: S1, pre-cutting, a pre-cutting punch and a pre-cutting counter plate are matched to cut a pre-cutting shape in a material belt; S2, local flattening, on the basis of the pre-cutting, a target area is subjected to thickness thinning and flattening treatment to form a variable cross-section structure; a flattening punch extrudes the target area of the material belt to complete the flattening, so that the material of the flattened area is extruded and flows to the pre-cuting direction; S3, blanking, a blanking punch and a blanking counter plate are matched to complete blanking of the part contour, and the blanking counter plate is provided with a local protrusion matched with the variable cross-section structure. Compared with the prior art, the application realizes high-precision integrated forming of a part with a flattening feature, greatly improves the production efficiency, shortens the processing cycle and reduces the manufacturing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision stamping of metal plates, and particularly relates to a stamping method and stamping die for a locally variable cross-section part. BACKGROUND

[0002] A traditional blanking process uses the gap between a punch and a die to cause the material to be sheared and separated, and is suitable for parts with equal thickness. For parts with variable cross-section, the shearing force, lateral force and impact force borne by the blade edges of the punch and the die at different cross-section positions during the blanking process differ greatly, which can cause the local area of the die to be subjected to excessive force, resulting in elastic or even plastic deformation, damage to the precision of the die and reduction in the service life of the die. Moreover, the deformation resistance and flow rate of the material in different cross-section regions differ, resulting in inconsistent quality of the sheared surface and difficulty in ensuring the dimensional accuracy.

[0003] More information related to the above technical solutions can be found in the following documents:

[0004] In the patent with the patent publication number CN102689149A, a continuous punch forging precision forming process for an automobile retainer part is disclosed. The steel plate is clamped by a feeding roller and fed into a multi-station punch forging forming die, and the workpiece is formed in four steps, namely, first step: punching an inner hole → second step: flattening / extruding a protrusion → third step: extruding a hole and forming a boss → fourth step: punching a boss hole / punching an inner hole / blanking, to obtain the final workpiece.

[0005] In the process of implementing the present application, the inventors have found the following problems in the prior art:

[0006] In the prior art, the fine blanking process and the flattening process are performed separately in two devices, the fine blanking process is performed after the flattening process, the quality of the sheared surface of the variable cross-section part is poor, the dimensional accuracy is low, and the production efficiency is low. SUMMARY

[0007] In view of the above problems, the present application provides a stamping method and stamping die for a locally variable cross-section part, which is used to solve the technical problems of the prior art, i.e., the fine blanking process and the flattening process are performed separately in two devices, the fine blanking process is performed after the flattening process, the quality of the sheared surface of the variable cross-section part is poor, the dimensional accuracy is low, and the production efficiency is low.

[0008] To achieve the above-mentioned purpose, in a first aspect, the present application provides a stamping method for a locally variable cross-section part, comprising the following steps:

[0009] S1, pre-cutting;

[0010] The blank holder force is provided by the blank holder top rod, the blank holder is pressed down to the material belt, the pre-cut convex die moves downward under the action of the blanking force, the pre-cut counter-pressure plate provides upward counter-pressure while moving downward under the action of the pre-cut convex die, and the pre-cut convex die and the pre-cut counter-pressure plate cooperate to cut the pre-cut shape on the material belt;

[0011] S2, local flattening, on the basis of the pre-cut, the target area is thinned and flattened to form a variable cross-section structure;

[0012] The material belt moves downward under the action of the blank holder force, the flattening punch cooperates with the blank holder, the flattening punch extrudes the target area of the material belt, and the material in the flattened area flows to the pre-cut direction;

[0013] S3, blanking;

[0014] The blank holder force is provided by the blank holder top rod, the blank holder is pressed down to the material belt, the blanking convex-concave die moves downward under the action of the blanking force, the blanking counter-pressure plate provides upward counter-pressure while moving downward under the action of the blanking convex-concave die, and the blanking convex-concave die and the blanking counter-pressure plate cooperate to complete the blanking of the part contour, and the blanking counter-pressure plate is provided with a local protrusion matched with the variable cross-section structure.

[0015] Unlike the prior art, the above technical solution cuts the material belt through the pre-cut to form a cavity on the material belt, which can provide material flow space for the subsequent flattening process, avoid excessive accumulation of material in the flattened area, improve the forming quality, ensure that there is enough material for the blanking after the flattening process, and at the same time, the pitch and the guiding property of the material belt are not damaged; the variable cross-section structure is formed by thinning and flattening the target area on the basis of the pre-cut, the flattening punch acts on the pre-cut area, the material in the flattened area is extruded and flows to the pre-cut direction, the flattening thickness is controlled accurately, the material flows smoothly, and defects such as collapse and tearing do not occur; the blanking convex-concave die and the blanking counter-pressure plate cooperate to complete the blanking of the part contour, and the local protrusion counter-pressure plate is provided for the variable cross-section area to realize uniform stress in multiple areas; in this way, high-precision integrated forming of the part with the flattening feature is realized, the flattening process requirement is introduced on the basis of the traditional fine blanking process, the integrated high-precision forming of the complex geometric shape is realized, the product contour is clear, the flattened area is flat, and the technical requirements of high-end equipment manufacturing on precision special-shaped stamping parts are met; the flattening and fine blanking processes are combined into a composite forming process, and the process combination mode of cutting first, then flattening and finally blanking is adopted, which realizes the collaborative forming of the flattening structure and the fine blanking contour without increasing additional processes, greatly improves the production efficiency, shortens the processing cycle, and reduces the manufacturing cost.

[0016] As an embodiment of the present application, in the S1 pre-cut, the pre-cut punch is a preset shape punch;

[0017] The narrowest width of the preset shape punch is calculated through the strip thickness, the strip thickness after the flattening forming, the area of the flattening forming area and the outer contour of the flattening area, and the narrowest width of the preset shape punch is greater than the material flow required distance;

[0018] The material flow required distance is calculated through the narrowest width of the preset shape punch, and the distance of the pre-cut contour distance from the outer contour of the finished part is obtained through the material flow required distance and the strip thickness after the flattening forming, and is applied to the pre-cut punch.

[0019] Therefore, in general, the wider the preset shape punch is, the better the strength is, and the preset shape punch is not easy to be damaged, but more strip is cut and more waste is increased, and a suitable narrowest width of the preset shape punch needs to be calculated, and the narrowest area of the preset shape punch needs to be ensured to have a certain width to ensure subsequent processing, and the preset shape punch cannot be made too narrow to save material, and the preset shape punch cannot be made too wide to increase more waste; the narrowest width of the preset shape punch is greater than the material flow required distance, so that the material has enough flow space in the subsequent flattening process, the preset shape punch is a strip structure, and in the present application, the preset shape punch is Z-shaped, the distance of the preset shape punch from the flattening area is calculated, the pre-cut size is reasonably set, a free boundary is formed, the material in the subsequent flattening area is directionally flowed, and forming defects such as cracking and material tearing are avoided.

[0020] As an embodiment of the present application, the narrowest width x2 of the preset shape punch is calculated through the strip thickness, the strip thickness after the flattening forming, the area of the flattening forming area and the outer contour of the flattening area, and the calculation formula is:

[0021]

[0022] Wherein, A is the area of the flattening forming area, t1 is the strip thickness, t2 is the strip thickness after the flattening forming, and l is the outer contour of the flattening area.

[0023] Therefore, the narrowest width of the preset shape punch is calculated through the strip thickness, the strip thickness after the flattening forming, the area of the flattening forming area and the outer contour of the flattening area, and a systematic pre-cut size calculation method is established, and a residual pre-cut size design formula suitable for different plate thicknesses, material strengths and flattening ratios is proposed according to the influence of the flattening process on the plastic flow behavior of the material.

[0024] As an embodiment of the present application, by presetting the narrowest width of the punch, the step of calculating the material flow distance is that, in the flattening process, the flow distance is different for different outer profiles, and the narrowest width of the preset shape punch is multiplied by the corresponding proportional coefficient to obtain the material flow distance.

[0025] In this way, in the flattening process, the flow distance is different for different outer profiles, and the corresponding proportional coefficient should be multiplied to ensure sufficient flow space.

[0026] As an embodiment of the present application, the distance x by which the pre-cut profile is expanded outward from the outer profile of the finished part is obtained from the material flow distance and the thickness of the material belt after flattening and forming, and the calculation formula is:

[0027] x = t2 + 2.5 - x1

[0028] Wherein, x1 is the material flow distance.

[0029] In this way, the distance by which the pre-cut profile is expanded outward from the outer profile of the finished part is obtained from the material flow distance and the thickness of the material belt after flattening and forming, the profile of the preset shape punch is kept deviated from the final product profile, the inner profile size of the punch is consistent with the outer profile of the final part, and the punch is expanded outward, the pre-cut size is reasonably set to form a free boundary, so that the subsequent flattening area material flows directionally, and forming defects such as cracking and material tearing are avoided.

[0030] As an embodiment of the present application, in the step of S2 local flattening, on the basis of the pre-cut, the target area is subjected to thickness reduction and flattening treatment to form a variable cross-section structure,

[0031] When the flattening punch is a lower flattening punch, the material belt moves downward under the action of the blank holder force with the blank holder ring, the flattening punch is fixed, and the blank holder ring continuously moves downward to extrude the material belt and complete the flattening.

[0032] When the flattening punch is an upper flattening punch, the material belt moves downward under the action of the blank holder force with the blank holder ring, and the material belt is fixed by the blank holder force after contacting the concave die. The flattening punch moves downward under the action of the blanking force to extrude the material belt and complete the flattening.

[0033] In this way, according to the flattening direction, the punch can be upper or lower, so that the material in the flattening area is extruded and flows in the direction of the pre-cut.

[0034] As an embodiment of the present application, in the step of S2 local flattening, on the basis of the pre-cut, the target area is subjected to thickness reduction and flattening treatment to form a variable cross-section structure, and a flattening punch with a preset curved surface shape is used to apply uniform pressure to the variable cross-section area.

[0035] Thus, in the extrusion process, the variable cross-section area is uniformly pressed by the pre-set curved surface-shaped flattening punch, the edge of the flattening punch has corresponding chamfer and transition to realize uniform transition and avoid defects such as tearing of the part material, the pre-set curved surface shape is designed according to the target part, the variable cross-section area on the part is uniformly transitioned to avoid sudden flattening of the part and defects such as tearing of the material.

[0036] To achieve the above object, in a second aspect, the inventor provides a local variable cross-section part stamping die for performing the local variable cross-section part stamping method as described in any one of the above aspects, comprising an upper die plate, an upper backing plate, an upper fixed plate, a lower fixed plate, a lower backing plate, a lower die plate, a blank holder, a blank holder seat, a pre-cut punch, a pre-cut counter-pressure plate, a flattening punch, a concave die, a blanking punch and die, and a blanking counter-pressure plate.

[0037] The upper die plate, the upper backing plate and the upper fixed plate are arranged from top to bottom in the vertical direction.

[0038] The concave die, the lower fixed plate, the lower backing plate and the lower die plate are arranged from top to bottom in the vertical direction.

[0039] The blank holder seat is sleeved outside the blank holder and connected with the blank holder, the pre-cut punch is arranged above the pre-cut counter-pressure plate, the bottom of the pre-cut punch is in a pre-set shape, the flattening punch is arranged behind the pre-cut punch and the pre-cut counter-pressure plate in the production direction, the blanking punch and die are arranged behind the flattening punch in the production direction, and the blanking punch is arranged above the blanking counter-pressure plate.

[0040] Different from the prior art, the local variable cross-section part stamping die of the technical solution of the present application realizes high-precision integrated forming of parts with flattening features, introduces flattening process requirements on the basis of traditional fine blanking process, realizes integrated high-precision forming of complex geometric shapes, and has clear product profile and high flatness of the flattening area, which meets the technical requirements of high-end equipment manufacturing on precision special-shaped stamping parts; the flattening and fine blanking processes are combined into a composite forming process, a process combination mode of cutting first, then flattening and finally blanking is adopted, and the pre-cut punch, the flattening punch, the blanking punch and die, and the fine blanking die work cooperatively, which realizes cooperative forming of the flattening structure and the fine blanking profile without increasing additional processes, greatly improves the production efficiency, shortens the processing cycle, and reduces the manufacturing cost.

[0041] As an embodiment of the present application, the shape of the contact surface of the flattening punch is a pre-set curved surface shape.

[0042] Thus, by applying uniform pressure on the variable cross-section area by the pre-set curved surface-shaped flattening punch, the edge of the flattening punch has corresponding chamfers and transitions, achieving uniform transition and avoiding defects such as tearing of the part material, the pre-set curved surface shape is designed according to the target part, so that the variable cross-section area on the part is uniformly transitioned, and sudden flattening of the part and defects such as tearing of the material are avoided.

[0043] As an embodiment of the present application, the top of the blanking counter-pressure plate is provided with a local protrusion matched with the variable cross-section structure.

[0044] Thus, the local protrusion counter-pressure plate is provided for the variable cross-section area, realizing uniform force on multiple areas, the shape of the local protrusion is matched with the variable cross-section structure, and the variable cross-section structure after flattening is supported, so that the semi-finished part can be attached to the counter-pressure plate, and in the process of real-time blanking and punching, the semi-finished part is stable and the punching force is uniform.

[0045] The above invention content is only a summary of the technical scheme of the present application, in order to enable those skilled in the art to more clearly understand the technical scheme of the present application, and then can be implemented according to the content of the description and the drawings, and in order to make the above-mentioned purpose and other purposes, characteristics and advantages of the present application more easily understood, the following is described in combination with the specific embodiments and drawings of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0046] The drawings are only used to show the principles, implementation modes, applications, characteristics and effects of the specific embodiments and other related contents of the present application, and cannot be considered as a limitation of the present application.

[0047] In the drawings of the specification:

[0048] Figure 1 The logic diagram of the local variable cross-section part stamping method of an embodiment of the present application;

[0049] Figure 2 The structure diagram of the local variable cross-section part stamping die of an embodiment of the present application;

[0050] Figure 3 The structure diagram of the pre-cut protruding punch and the pre-cut counter-pressure plate of an embodiment of the present application;

[0051] Figure 4 The top view of the pre-cut protruding punch and the material belt of an embodiment of the present application;

[0052] Figure 5 The schematic diagram of the pre-cut shape and the flattening area of an embodiment of the present application;

[0053] Figure 6 The schematic diagram of the distance x required for material flow of an embodiment of the present application;

[0054] Figure 7 A schematic view of the local flattening material flow for an embodiment of the present application;

[0055] Figure 8 A schematic view of the structure of the flattening punch for an embodiment of the present application;

[0056] Figure 9 A schematic view of the structure of the blanking punch and blanking counter plate for an embodiment of the present application;

[0057] Figure 10 A schematic view of the structure of the blanking punch and blanking counter plate for an embodiment of the present application at another cross-sectional angle.

[0058] The reference signs mentioned in the above-mentioned figures are explained as follows:

[0059] x, the distance of the pre-cutting contour from the outer contour of the finished part;

[0060] 1, upper die plate, 2, upper backing plate, 3, upper fixed plate, 4, lower fixed plate, 5, lower backing plate, 6, lower die plate, 7, blank holder, 8, blank holder seat, 9, pre-cutting counter plate, 10, pre-cutting punch, 11, flattening punch, 12, blanking punch and die, 13, blanking counter plate, 14, local protrusion, 15, material strip, 16, die, 17, flattening area, 18, target part. DETAILED DESCRIPTION

[0061] In order to describe the possible application scenarios, technical principles, specific implementation schemes, and the purposes and effects that can be achieved of the present application in detail, the following will be described in detail in combination with the specific embodiments listed and the accompanying drawings. The embodiments described in the present document are only used to more clearly illustrate the technical schemes of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0062] In the present document, the term "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the present application. The term "embodiment" appearing at various positions in the specification does not necessarily refer to the same embodiment, and does not particularly limit the independence or association between other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical scheme.

[0063] Unless otherwise defined, the meanings of the technical terms used in the present document are the same as those commonly understood by the person skilled in the art to which the present application belongs; the use of related terms in the present document is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0064] In the description of the present application, the phrase "and / or" is a description of a logical relationship between objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character " / " herein generally represents that the associated objects before and after are a "or" logical relationship.

[0065] In the present application, phrases such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary and secondary, or order relationship between the entities or operations.

[0066] Without more limitations, in the present application, the "includes", "contains", "has" or other similar expressions used in the sentence are intended to cover non-exclusive inclusion, and these expressions do not exclude the presence of other elements in the process, method or product including the described elements, so that the process, method or product including a series of elements can not only include those limited elements, but also include other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0067] As the same understanding in the "Guidelines for Examination", in the present application, the expressions such as "greater than", "less than", "exceed" are understood as not including the number; "above", "below", "within" and other expressions are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times" and the like, unless otherwise explicitly limited.

[0068] In the prior art, the fine blanking process and the flattening process are carried out in two devices, and the fine blanking process is carried out after the flattening process. The quality of the cutting surface of the blanking of the variable cross-section part is poor, the size precision is low, and the production efficiency is low.

[0069] In view of this, the embodiment of the application provides a stamping method and a stamping die for a locally variable cross-section part, comprising the following steps: S1, pre-cutting, a pre-cutting punch 10 and a pre-cutting counter-pressure plate 9 cooperate to cut a pre-cutting of a preset shape on a material strip 15; S2, local flattening, based on the pre-cutting, a target area is subjected to thickness reduction and flattening treatment to form a variable cross-section structure, so that the material of a flattened area 17 is extruded and flows in the direction of the pre-cuting; and S3, blanking, a blanking punch and die 12 and a blanking counter-pressure plate 13 cooperate to complete blanking of the outline of the part, and the blanking counter-pressure plate 13 is provided with a local protrusion 14 that cooperates with the variable cross-section structure. The flattening and fine blanking processes are combined into a composite forming process, and the process combination of pre-cutting, then flattening and finally blanking is adopted, so that the flattening structure and the fine blanking outline are co-formed without increasing additional processes, the production efficiency is greatly improved, the processing cycle is shortened, and the manufacturing cost is reduced.

[0070] According to some embodiments of the application, referring to Figures 1 to 10 , the embodiment relates to a stamping method for a locally variable cross-section part, comprising the following steps:

[0071] S1, pre-cutting;

[0072] The blank holder 7 provides a blanking force through a top rod of the blank holder 7, the blank holder 7 presses the material strip 15 downward, the pre-cutting punch 10 moves downward under the action of a blanking force, the pre-cutting counter-pressure plate 9 provides upward counter-pressure at the same time, and under the action of the pre-cutting punch 10, the pre-cutting counter-pressure plate 9 moves downward, the pre-cutting punch 10 and the pre-cutting counter-pressure plate 9 cooperate to cut a pre-cutting of a preset shape on the material strip 15;

[0073] S2, local flattening, based on the pre-cutting, a target area is subjected to thickness reduction and flattening treatment to form a variable cross-section structure;

[0074] The material strip 15 moves downward under the action of the blanking force along with the blank holder 7, the flattening punch 11 cooperates with the blank holder 7, the flattening punch 11 extrudes the target area of the material strip 15 to complete flattening, so that the material of the flattened area 17 is extruded and flows in the direction of the pre-cutting;

[0075] S3, blanking;

[0076] The blank holder 7 provides a blanking force through a top rod of the blank holder 7, the blank holder 7 presses the material strip 15 downward, the pre-cutting punch 10 moves downward under the action of a blanking force, the pre-cutting counter-pressure plate 9 provides upward counter-pressure at the same time, and under the action of the pre-cutting punch 10, the pre-cutting counter-pressure plate 9 moves downward, the pre-cutting punch 10 and the pre-cutting counter-pressure plate 9 cooperate to cut a pre-cutting of a preset shape on the material strip 15;

[0077] In this embodiment, the blanking is completed by a progressive die structure, and the process includes three steps: pre-cutting, flattening, and precision blanking.

[0078] In the pre-cutting step, the blank holder 7 provides a blanking force through the ejector pin, the blank holder 7 presses the material strip 15 downward to prevent the material from slipping or wrinkling laterally, and fixes the material strip. Under the action of the blanking force, the pre-cutting punch 10 moves downward, and the pre-cutting counter-pressure plate 9 moves downward under the action of the pre-cutting punch 10 while providing upward counter-pressure through the pre-cutting counter-pressure plate 9. The pre-cutting punch 10 cuts a cavity in the material strip 15 to provide a material flow space for the subsequent flattening process, avoid excessive accumulation of material in the flattening area, improve the forming quality, ensure that there is enough material for the blanking after the flattening process, and at the same time, do not damage the pitch and guidance of the material strip. The pre-cutting blanking structure adopts a conventional fine blanking process structure to avoid edge tearing and improve the quality of the subsequent flattening process.

[0079] In the flattening step, the target area is thinned and flattened based on the pre-cutting to form a variable cross-section structure. The variable cross-section is actually flattening. From the cross-section of the part, the thickness is reduced from 5 mm to 3 mm, which is a variable cross-section. A pre-set curved flattening punch applies uniform pressure to the variable cross-section area, causing the material in the flattening area to be extruded and flow in the direction of the pre-cutting. The flattening shape is consistent, the thickness is accurately controlled, the material flows smoothly, and defects such as collapse and tearing do not occur.

[0080] In the blanking step, the two-cavity part in the local variable cross-section part stamping method of the present application adopts a staggered interval blanking method to disperse the blanking load. The blank holder 7 provides a blanking force through the ejector pin, and the blank holder 7 presses the material strip 15 downward to prevent the material from slipping or wrinkling laterally and fix the material strip. Under the action of the blanking punch and die 12, the blanking counter-pressure plate 13 moves downward, and the blanking punch and die 12 and the blanking counter-pressure plate 13 cooperate to complete the blanking of the part outline, and the final fine blanking of the part outline is completed. For the variable cross-section structure, the blanking counter-pressure plate 13 is provided with a local protrusion 14 that cooperates with the variable cross-section structure to realize uniform stress in multiple areas. The local protrusion 14 on the blanking counter-pressure plate 13 is a support in the vertical direction for the variable cross-section structure. In addition, for different thickness areas, the concave die 16 is designed with different blanking gaps to realize gap control and regional adaptability adjustment. The blanking gap of the variable cross-section part in different thickness areas is different, and the blanking gap refers to the gap between the blanking punch and die 12 and the concave die 16, which is a support in the horizontal direction.

[0081] The pre-cutting of the material belt 15 forms a cavity on the material belt 15, which can provide a material flow space for the subsequent flattening process, avoid excessive accumulation of materials in the flattening area 17, improve the forming quality, ensure that there is enough material for the blanking after the flattening process, and at the same time, the pitch and the guiding property of the material belt 15 are not damaged; by reducing the thickness of the target area based on the pre-cutting, a variable cross-section structure is formed, the pre-cutting area is acted on by the flattening punch 11, so that the material in the flattening area 17 is extruded and flows in the direction of the pre-cutting, the flattening thickness is accurately controlled, the material flows smoothly, and defects such as collapse and tearing do not occur; the blanking punch and die 12 and the blanking counter-pressure plate 13 cooperate to complete the blanking of the part contour, and the local protrusion 14 counter-pressure plate is arranged in the variable cross-section area to realize uniform stress in multiple areas.

[0082] In this way, high-precision integrated forming of parts with flattening features is realized, the flattening process requirement is introduced on the basis of the traditional fine blanking process, the integrated high-precision forming of complex geometric shapes is realized, the product contour is clear, the flattening area 17 has high flatness, and the technical requirements of high-end equipment manufacturing on precision special-shaped stamping parts are met; the flattening and fine blanking processes are combined into a composite forming process, and the process combination mode of cutting first, then flattening and finally blanking is adopted, so that the flattening structure and the fine blanking contour are cooperatively formed without increasing additional processes, the production efficiency is greatly improved, the processing cycle is shortened, and the manufacturing cost is reduced.

[0083] According to some embodiments of the present application, as shown in Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 indicates that in the pre-cutting S1, the pre-cutting punch 10 is a pre-set shape punch;

[0084] The narrowest width of the pre-set shape punch is calculated based on the thickness of the material belt 15, the thickness of the material belt 15 after flattening forming, the area of the flattening forming area, and the outer contour of the flattening area 17, and the narrowest width of the pre-set shape punch is greater than the required distance of material flow;

[0085] The required distance of material flow is calculated based on the narrowest width of the pre-set shape punch, and the pre-cutting contour distance is obtained based on the required distance of material flow and the thickness of the material belt 15 after flattening forming (such as the distance indicated by x in Figure 6 , which is applied to the pre-cutting punch 10.

[0086] Therefore, in general, the wider the preset shape punch is, the better the strength is, and the preset shape punch is not easy to be damaged, but more material strips 15 are cut out, more waste is increased, and a suitable narrowest width of the preset shape punch needs to be calculated, and the narrowest area of the preset shape punch needs to be ensured to have a certain width to ensure subsequent processing, and the preset shape punch cannot be made too narrow to save material, and the preset shape punch cannot be made too wide to increase more waste; by making the narrowest width of the preset shape punch greater than the distance required by material flow, it is ensured that there is sufficient flow space for the material in the subsequent flattening process; in the present application, the preset shape punch is a strip structure, and the cross-sectional shape is Z-shaped, so the distance between the preset shape punch and the flattening area 17 needs to be calculated, and the free boundary is formed by reasonably setting the pre-cut size, so that the material in the subsequent flattening area 17 flows directionally, and forming defects such as cracking and material tearing are avoided.

[0087] According to some embodiments of the present application, optionally, as shown in Figure 6 The narrowest width x2 of the preset shape punch is calculated by the thickness of the material strip 15, the thickness of the material strip 15 after flattening forming, the area A of the flattening forming area, and the outer contour of the flattening area 17, and the calculation formula is as follows:

[0088]

[0089] Wherein, A is the area of the flattening forming area, t1 is the thickness of the material strip 15, t2 is the thickness of the material strip 15 after flattening forming, and l is the outer contour of the flattening area 17.

[0090] Therefore, the narrowest width of the preset shape punch is calculated by the thickness of the material strip 15, the thickness of the material strip 15 after flattening forming, the area of the flattening forming area, and the outer contour of the flattening area 17, and a systematic pre-cut size calculation method is established, and a pre-cut size design formula suitable for different plate thicknesses, material strengths and flattening ratios is proposed according to the influence of the flattening process on the plastic flow behavior of the material.

[0091] According to some embodiments of the present application, optionally, as shown in Figure 5 The step of calculating the distance required by material flow by the narrowest width of the preset shape punch is that, in the flattening process, the flow distance is different for different outer contours, and the narrowest width of the preset shape punch is multiplied by the corresponding proportional coefficient to obtain the distance required by material flow.

[0092] In the present embodiment, the pre-cut punch 10 (preset shape punch) is a strip structure, and the cross-sectional shape is Z-shaped;

[0093] Therefore, in the flattening process, the flow distance is different for different outer contours, and the corresponding proportional coefficient should be multiplied to ensure sufficient flow space. The specific proportional coefficient is shown in the following table:

[0094] Convex x1 = (0.9-1) x2 Straight line x1 = (0.96 ~ 1.005) x2 Concave x1 = (1 ~ 1.1) x2

[0095] x2 in the above table is the narrowest width x2 of the preset shape punch appearing in the above formula, and a distance x1 required for material flow is derived.

[0096] According to some embodiments of the present application, optionally, a distance x (as indicated by x in Figure 6 , a distance required for material flow, the thickness of the material strip 15 after the flattening forming, is derived.

[0097] x = t2+2.5-x1

[0098] Wherein, x1 is the distance required for material flow.

[0099] In the embodiment, the system's cut size calculation method is established, and the excess cut size design formula suitable for different plate thicknesses, material strengths and flattening ratios is proposed in view of the influence of the flattening process on the plastic flow behavior of the material.

[0100] In this way, a distance x (as indicated by x in Figure 6 , a distance required for material flow, the thickness of the material strip 15 after the flattening forming, is derived.

[0101] According to some embodiments of the present application, optionally, in S2, local flattening is performed on the basis of the pre-cut to perform thickness reduction and flattening processing on the target area, and in the step of forming a variable cross-section structure,

[0102] When the flattening punch 11 is a lower flattening punch 11, the material strip 15 moves downward with the pressure ring 7 under the action of the pressure force, the flattening punch 11 is fixed, and the pressure ring 7 continuously moves downward to extrude the material strip 15, thereby completing the flattening.

[0103] When the flattening punch 11 is an upper flattening punch 11, the material strip 15 moves downward with the pressure ring 7 under the action of the pressure force, and after the material strip 15 contacts the concave die 16, the pressure force fixes the material strip 15, the flattening punch 11 moves downward under the action of the blanking force to extrude the material strip 15, thereby completing the flattening.

[0104] As shown in Figure 8 , in the embodiment, the flattening punch 11 is a lower flattening punch 11, and both the lower flattening punch 11 and the upper flattening punch 11 are within the protection scope of the present embodiment.

[0105] Thus, the punch can be arranged above or below according to the direction of the flattening, so that the material in the flattening area 17 is extruded and flows in the direction of the pre-cut.

[0106] According to some embodiments of the present application, the target area is subjected to thickness reduction and flattening treatment on the basis of the pre-cut in the step of forming the variable cross-section structure, and the flattening punch 11 with a preset curved surface shape is used to apply uniform pressure to the variable cross-section area.

[0107] Thus, during the extrusion process, the flattening punch 11 with a preset curved surface shape is used to apply uniform pressure to the variable cross-section area, and the edges of the flattening punch 11 have corresponding chamfers and transitions to achieve uniform transition and avoid defects such as tearing of the part material. The preset curved surface shape is designed according to the target part 18, so that the variable cross-section area on the part is uniformly transitioned to avoid sudden flattening of the part and defects such as tearing of the material.

[0108] The technical key points in the present embodiment are as follows: the pre-cut design for the variable cross-section area, the pre-cut is a center opening structure, which can effectively alleviate the problem of uneven flow of the material during flattening; and the pre-cut position before flattening is optimized to control the distance x between the pre-cut contour and the boundary of the final product, which is a key parameter to ensure the deformation accuracy of the material after flattening and the clarity of the final contour.

[0109] The process of the present application has strong universality and wide application range. The fine blanking process proposed in the present application is not only suitable for processing single type of parts, but also can be applied to fine blanking part manufacturing of various materials, various thicknesses and various complex structures.

[0110] The present embodiment also relates to a local variable cross-section part stamping die for performing the local variable cross-section part stamping method according to any one of the above embodiments, which comprises an upper die plate 1, an upper cushion plate 2, an upper fixed plate 3, a lower fixed plate 4, a lower cushion plate 5, a lower die plate 6, a blank holder 7, a blank holder seat 8, a pre-cut punch 10, a pre-cut counter plate 9, a flattening punch 11, a die 16, a blanking punch and die 12, and a blanking counter plate 13.

[0111] The upper die plate 1, the upper cushion plate 2 and the upper fixed plate 3 are arranged from top to bottom in the vertical direction.

[0112] The die 16, the lower fixed plate 4, the lower cushion plate 5 and the lower die plate 6 are arranged from top to bottom in the vertical direction.

[0113] The blank holder seat 8 is sleeved outside the blank holder 7 and connected with the blank holder 7, the pre-cut convex die 10 is arranged above the pre-cut counter-pressure plate 9, the bottom of the pre-cut convex die 10 is in a preset shape, the flattening punch 11 is arranged behind the pre-cut convex die 10 and the pre-cut counter-pressure plate 9 in the production direction, the blanking convex-concave die 12 and the blanking counter-pressure plate 13 are arranged behind the flattening punch 11 in the production direction, and the blanking convex-concave die 12 is arranged above the blanking counter-pressure plate 13.

[0114] In the embodiment, the upper die plate 1, the upper backing plate 2 and the upper fixed plate 3 are arranged in the upper half of the stamping die, the concave die 16, the lower fixed plate 4, the lower backing plate 5 and the lower die plate 6 are arranged in the lower half of the stamping die, the upper fixed plate 1 is above the transition plate, the lower die plate 6 is below the transition plate, the upper and lower surfaces of the machine tool provide the oil cylinder for providing counter-pressure and blank holder force, but the size is limited, the die is too large, the ejector rod is out of the range of the oil cylinder, and the transition plate is needed, which is equivalent to expanding the ejection surface of the oil cylinder for providing counter-pressure and blank holder force, and the principle and structure are conventional technical means.

[0115] The blank holder 7, the blank holder seat 8, the pre-cut convex die 10, the pre-cut counter-pressure plate 9, the flattening punch 11, the blanking convex-concave die 12 and the blanking counter-pressure plate 13 are arranged between the upper fixed plate 3 and the lower fixed plate 4.

[0116] In the embodiment, the concave die 16 is further included, the material belt 15 is located between the blank holder 7 and the concave die 16, the pre-cut convex die 10 and the pre-cut counter-pressure plate 9, the flattening punch 11, the blanking convex-concave die 12 and the blanking counter-pressure plate 13 are arranged in sequence in the production direction, the pre-cut convex die 10 and the pre-cut counter-pressure plate 9 perform pre-cutting on the material belt 15 to cut a cavity, that is, a through hole, on the material belt 15, the flattening punch 11 flattens the target area to flow the material to the pre-cutting direction, and the pre-cut convex die 10 and the pre-cut counter-pressure plate 9 realize fine blanking, and the specific stamping structure and principle are conventional technical means, which will not be described here.

[0117] In the embodiment, the convex-concave die refers to a die mechanism that bears the function of the convex die and the function of the concave die, the blanking die is a convex-concave die, and the pre-cutting is only a convex die.

[0118] The partial variable cross-section part stamping die of the application realizes high-precision integrated forming of the part with the flattening feature, introduces the flattening process requirement on the basis of the traditional fine blanking process, realizes integrated high-precision forming of the complex geometric appearance, the product contour is clear, the flattening area 17 has high flatness, and the technical requirements of high-end equipment manufacturing on the precision special-shaped stamping part are met; the flattening and fine blanking processes are combined into a composite forming process, a process combination mode of cutting first, then flattening and finally blanking is adopted, the pre-cutting punch 10, the flattening punch 11, the blanking punch and die 12 and the fine blanking die are combined to work, the flattening structure and the fine blanking contour are cooperatively formed without increasing additional processes, the production efficiency is greatly improved, the processing cycle is shortened, and the manufacturing cost is reduced.

[0119] According to some embodiments of the application, optionally, the shape of the contact surface of the flattening punch 11 is a preset curved surface shape.

[0120] In this way, the flattening punch 11 with the preset curved surface shape uniformly applies pressure to the variable cross-section area, the edge of the flattening punch 11 has corresponding chamfers and transitions, uniform transition is realized, and defects such as tearing of the part material are avoided, the preset curved surface shape is designed according to the target part 18, the variable cross-section area on the part is uniformly transitioned, and defects such as tearing of the part material are avoided.

[0121] According to some embodiments of the application, optionally, as shown in Figure 9 The top of the blanking counter-pressure plate 13 is provided with a local protrusion 14 matched with the variable cross-section structure.

[0122] As shown in Figure 10 The schematic diagram of the blanking step is shown in Figure 10 are different angle views, Figure 10 In the schematic diagram of the blanking step, the part has a hole in the middle, the punching hole is upward, and the target part 18 is punched out;

[0123] In this way, the local protrusion 14 counter-pressure plate is provided for the variable cross-section area, uniform stress is realized in multiple areas, the shape of the local protrusion 14 is matched with the variable cross-section structure, the variable cross-section structure after flattening is supported, and the semi-processed part can be attached to the counter-pressure plate. In the process of real-time blanking and punching, the semi-processed part is stable and the punching force is uniform.

[0124] It should be noted that although the above embodiments have been described in the present text, the patent protection scope of the application is not limited thereby. Therefore, based on the innovative idea of the application, changes and modifications are made to the embodiments described in the present text, or equivalent structures or equivalent process transformations are made using the content of the application specification and drawings, and the above technical solutions are directly or indirectly applied to other related technical fields, which are all included in the patent protection scope of the application.

Claims

1. A stamping method for parts with locally variable cross-sections, characterized in that, Includes the following steps: S1, pre-cut; The blank holder provides blanking force through the blank holder ring push rod. The blank holder ring presses the strip downwards. The pre-cutting punch moves downwards under the action of the punching force. At the same time, the pre-cutting counter-pressure plate provides counter-pressure upwards. Under the action of the pre-cutting punch, the pre-cutting counter-pressure plate moves downwards. The cooperation between the pre-cutting punch and the pre-cutting counter-pressure plate cuts a pre-cut shaped pre-cut into the strip. S2. Local flattening: Based on the pre-cut, the target area is thinned and flattened to form a variable cross-section structure. As the pressure ring moves downwards, the material strip moves with the pressure ring. The flattening punch and the pressure ring work together to compress the target area of ​​the material strip, thus flattening it. The material in the flattened area is compressed and flows towards the pre-cut direction. S3, material unloading; The blanking ring provides blanking force through the top rod, and the blanking ring presses the material strip downward. Under the action of the blanking force, the blanking punch and die move downward. At the same time, the blanking counter pressure plate provides counter pressure upward. Under the action of the blanking punch and die, the blanking counter pressure plate moves downward. The blanking punch and die and the blanking counter pressure plate cooperate to complete the blanking of the part's outline. For variable cross-section structures, the blanking counter pressure plate is provided with local protrusions that cooperate with the variable cross-section structure.

2. The stamping method for locally variable cross-section parts according to claim 1, characterized in that, In the S1 pre-cut, the pre-cut punch is a punch of a preset shape; The narrowest width of the pre-shaped punch is calculated by the material strip thickness, the material strip thickness after flattening, the area of ​​the flattening region, and the outer contour of the flattening region. The narrowest width of the pre-shaped punch is greater than the distance required for material flow. By calculating the minimum width of the pre-shaped punch, the distance required for material flow is determined. Based on the required material flow distance and the thickness of the flattened strip, the distance between the pre-cut contour and the outer contour of the finished part is obtained and applied to the pre-cut punch.

3. The stamping method for locally variable cross-section parts according to claim 2, characterized in that, The minimum width x2 of the punch with the preset shape is calculated by taking the material strip thickness, the thickness of the material strip after flattening, the area of ​​the flattening region, and the outer contour of the flattening region. The calculation formula is as follows: Where A is the area of ​​the flattened forming region, t1 is the thickness of the strip, t2 is the thickness of the strip after flattening, and l is the outer contour of the flattened region.

4. The stamping method for locally variable cross-section parts according to claim 3, characterized in that, The steps for calculating the required material flow distance by using the narrowest width of the preset shaped punch are as follows: During the flattening process, the flow distance varies for different shapes and contours. The narrowest width of the preset shaped punch is multiplied by the corresponding proportional coefficient to obtain the required material flow distance.

5. The stamping method for locally variable cross-section parts according to claim 4, characterized in that, The distance x between the pre-cut contour and the outer contour of the finished part can be obtained by considering the distance required for material flow and the thickness of the flattened strip. The calculation formula is as follows: x = t² + 2.5 - x¹ Where x1 is the distance required for material flow.

6. The stamping method for locally variable cross-section parts according to claim 1, characterized in that, In the step of locally flattening S2, based on the pre-cut, the target area is thinned and flattened to form a variable cross-section structure. When the flattening punch is a bottom-mounted flattening punch, the material strip moves downward with the pressure ring under the action of the pressure force. The flattening punch remains stationary, while the pressure ring continues to move downward, squeezing the material strip to complete the flattening. When the flattening punch is an upper-positioned flattening punch, the strip moves downward along with the blank holder ring under the action of the blank holder force. After the strip contacts the die, the blank holder force fixes the strip, and the flattening punch moves downward under the action of the blanking force to squeeze the strip and complete the flattening.

7. The stamping method for locally variable cross-section parts according to claim 6, characterized in that, In the step of local flattening in S2, based on the pre-cut, the target area is thinned and flattened to form a variable cross-section structure. In this step, a flattening punch with a preset curved shape is used to apply uniform pressure to the variable cross-section area.

8. A stamping die for a part with a partially variable cross-section, characterized in that, The method for performing the stamping method for partially variable cross-section parts as described in any one of claims 1-7 includes an upper template, an upper pad, an upper fixed plate, a lower fixed plate, a lower pad, a lower template, a pressure ring, a pressure ring seat, a pre-cut punch, a pre-cut counter-pressure plate, a flattening punch, a die, blanking punch and die, and a blanking counter-pressure plate. The upper template, the upper pad, and the upper fixing plate are arranged vertically from top to bottom; The concave mold, the lower fixing plate, the lower pad, and the lower template are arranged vertically from top to bottom; The pressure ring seat is sleeved outside the pressure ring and connected to the pressure ring. The pre-cutting punch is positioned opposite to the pre-cutting counter-pressure plate above it. The bottom shape of the pre-cutting punch is a preset shape. The flattening punch is positioned behind the pre-cutting punch and the pre-cutting counter-pressure plate in the production direction. The blanking punch and die are positioned behind the blanking counter-pressure plate in the production direction of the flattening punch. The blanking punch and die are positioned opposite to each other above the blanking counter-pressure plate.

9. The stamping die for partially variable cross-section parts according to claim 8, characterized in that, The contact surface of the flattening punch has a preset curved shape.

10. The stamping die for partially variable cross-section parts according to claim 9, characterized in that, The top of the material feeding counter-pressure plate is provided with a local protrusion that matches the variable cross-section structure.

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