Stamping forming method
Through the two-stage forming process, the material flow of shrinkage and extension flange deformation is alleviated, and the problem of wrinkles and cracks of high-strength steel plates in stamping and forming automobile parts is solved, achieving high-quality stamping and forming.
Patent Information
- Application Number
- CN202180035893.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-05-23
- Filing Date
- 2021-04-08
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2041-04-08
AI Technical Summary
High-strength steel plates are prone to wrinkles and cracks during stamping and forming of automotive parts, especially at flanges, which are difficult to effectively suppress in the prior art.
The two-stage forming process is adopted, first forming an intermediate forming member through the first forming process, including forming a torsional shape part at the convex edge to alleviate the deformation of the contraction flange, and then in the second forming process, the material inflow of the torsional shape part is used to suppress the deformation of the stretched flange, so as to achieve uniform distribution of the material.
It effectively suppresses the wrinkles and cracks in the flange area, improves the quality of stamped molded parts, and is suitable for automotive parts with concave and convex edges, such as sliding door tracks.
Smart Images
Figure CN115666808B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a press forming method for press forming accessories such as automotive parts from a metal sheet, and particularly relates to a press forming method for a press formed part having a top portion with convex and concave parts in the in-plane direction and a flange portion formed continuously with the top portion. Background Art
[0002] In recent years, due to the weight reduction of automotive bodies caused by environmental problems, high-strength steel sheets are widely used for automotive parts. However, compared with steel sheets having low strength, high-strength steel sheets lack ductility and are prone to fracture during processing. In addition, when high-strength steel sheets are used, thinning is also carried out for further weight reduction, so there is also a problem that buckling of the steel sheet is likely to occur and wrinkles are likely to occur during press forming. Therefore, there is a strong demand for the development of a press forming method for suppressing fracture and wrinkles.
[0003] For example, Patent Document 1 discloses a press forming method for manufacturing automotive parts that are prone to wrinkles and stretch flange cracks inside the product without forming defects by using a blank holder that is separately driven from the punch and the die for press. According to the method disclosed in Patent Document 1, automotive parts that are prone to wrinkles and cracks inside the product can be manufactured without forming defects.
[0004] Patent Document 1: Japanese Patent No. 6032374 Gazette
[0005] However, the press forming method disclosed in Patent Document 1 is a method that requires the use of a blank holder to hold down the inside of the product away from the flange. Therefore, there is a problem that it cannot be applied to a shape in which wrinkles and cracks occur in the flange portion itself. Summary of the Invention
[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a stamping method that can also be applied to a stamped part in which wrinkles and cracks are generated in the flange itself and can suppress wrinkles and cracks generated in the flange at the same time.
[0007] The stamping method according to the present invention is a method for forming a stamped part, the stamped part having: a top plate portion having a convex and concave outer edge portion in which a convex outer edge part and a concave outer edge part are continuous via a connecting outer edge part, the convex outer edge part protruding outward in the in-plane direction, and the concave outer edge part being recessed inward in the in-plane direction; and a flange portion formed continuously with the convex and concave outer edge portion in the top plate portion, wherein the stamping method includes: a first forming step in which a preformed part is formed, the preformed part having a flange portion formed in the convex outer edge part and a torsional deformation part having a shape twisted toward the concave outer edge part and formed continuously with the flange portion in the connecting outer edge part; and a second forming step in which the torsional deformation part is formed into a flange portion and a flange portion is formed in the concave outer edge part to form the preformed part formed in the first forming step into a target shape.
[0008] The above first forming step and the above second forming step can be formed by different tools of press forming.
[0009] The above first forming step and the above second forming step can be performed by one tool.
[0010] According to the stamping method of the present invention, in the first forming step, generation of wrinkles caused by shrink flange forming is suppressed, and in the second forming step, generation of cracks caused by stretch flange forming is suppressed, and generation of wrinkles and cracks can be suppressed throughout the process. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is an explanatory view of the stamping method according to an embodiment of the present invention.
[0012] Figure 2 is Figure 1 An enlarged view of the AA portion of the preformed part in the first forming step in
[0013] Figure 3 It is an explanatory diagram for explaining the mechanism of suppressing the generation of wrinkles in the first forming process.
[0014] Figure 4 It is Figure 1 an enlarged view of the BB part of the target shape in the second forming process in
[0015] Figure 5 It is an explanatory diagram for explaining the mechanism of suppressing the generation of cracks in the second forming process.
[0016] Figure 6 It is an explanatory diagram for explaining the target shape in the embodiment and the problems generated in the forming process of the target shape.
[0017] Figure 7 It is for Figure 6 explaining the mechanism of generating wrinkles and cracks in the forming process of the target shape shown in Detailed Embodiment
[0018] Before explaining the stamping method of the present embodiment, regarding an example of the stamping part to be formed by the present invention, based on Figure 6 , Figure 7 its shape and problems will be explained. Figure 6 The stamping part 1 shown in Figure 6 is a perspective view of a slide door rail as an automotive part, and has a top plate part 3 and a flange part 5. The top plate part 3 has a convex part 7 that protrudes outward in the in-plane direction and a concave part 9 that is adjacent to the convex part 7 and recesses inward in the in-plane direction. The outer periphery of the top plate part 3 becomes an uneven edge part 11 composed of the outer periphery of the convex part 7, that is, the convex edge part 11a, the outer periphery of the concave part 9, that is, the concave edge part 11b, and the connecting edge part 11c that connects the convex edge part 11a and the concave edge part 11b. And a flange part 5 is formed on the uneven edge part 11. In addition, in the case of an actual slide door rail, a bending part is formed on the edge part of the top plate part 3 that faces the uneven edge part 11 where the flange part 5 is formed, but in
[0019] When forming such a stamped part 1 by an existing stamping method, in the flange portion 5 formed on the convex edge portion 11a, a shrink flange deformation (portion a enclosed by a circular dotted line in the figure) occurs, and wrinkles are likely to be generated due to excess metal. On the other hand, in the flange portion 5 formed on the concave edge portion 11b, an expand flange deformation (portion b enclosed by a circular dotted line in the figure) occurs, and cracks are likely to be generated due to metal shortage.
[0020] Based on Figure 7 to explain the mechanism for generating such wrinkles and cracks. Figure 7 is a diagram for explaining the metal flow during the forming process in the EE portion enclosed by a dotted line of Figure 6 , showing a top view observation ( Figure 7 of (a)) and a side view observation ( Figure 7 of (b)) Figure 6 of the state. In addition, in Figure 7 , the dotted line is the front end of the blank before forming, and the solid line is the end edge of the flange portion 5 formed into the target shape. In addition, points D and B in the figure are points corresponding to the R end points (the boundary between a curve and a straight line) of the convex edge portion 11a in the blank before forming, and correspondingly, the intersection points of the lines perpendicular to the end edge of the target shape from points D and B in the top view with the end edge of the target shape are points D' and B'. Similarly, points A and E in the figure are points corresponding to the R end points of the concave edge portion 11b in the blank before forming, and correspondingly, the intersection points of the lines perpendicular to the end edge of the target shape from points E and A in the top view with the end edge of the target shape are points A' and E'. As shown in Figure 7 of (a) top view, the material flows substantially perpendicular to the ridge line (curved line), so in portion a, it flows in the direction approaching the material, and in portion b, it flows in the direction away from the material. Therefore, wrinkles are likely to be generated in portion a, and cracks are likely to be generated in portion b.
[0021] To solve such problems, the inventor came up with a stamping method that can avoid the concentration of compressive strain and tensile strain in each part by interposing an intermediate forming part that can easily make the material flow from the part where shrink flange deformation occurs to the part where expand flange deformation occurs during the forming process. Specifically, the stamping method is composed of the following structure.
[0022] As Figure 1As shown, the stamping forming method of this embodiment includes: a first forming step S1 of forming a blank made of a metal sheet 13 into an intermediate formed part 15; and a second forming step S3 of forming the intermediate formed part 15 formed in the first forming step S1 into a target shape. Hereinafter, each step will be described. In addition, in Figure 1 the same reference numerals are assigned to the same parts as those shown in the Figure 6 target shape.
[0023] <First Forming Step>
[0024] The first forming step S1 is a step of forming the intermediate formed part 15 from the blank. The intermediate formed part 15 has: a flange part 5 formed on the convex edge part 11a; and a twisted shape part 17, which is continuous with the flange part 5 and formed on the connecting edge part 11c of the target shape.
[0025] During the forming process of the intermediate formed part in the first forming step S1, the flange part 5 is formed on the convex edge part 11a of the top plate part 3, but the twisted shape part 17 is formed on the concave edge part 11b instead of the flange part 5. As Figure 2 shown, one end side of the twisted shape part 17 is connected to the flange part 5 formed on the convex edge part 11a, and the other end side is connected to the flat top plate part 3, so it becomes a twisted shape. When forming the twisted shape part 17, as Figure 2 shown by the arrow, metal inflow occurs from the side of the formed flange part 5 toward the flat direction, and the remaining material in the shrinking flange deformation is alleviated, and the generation of wrinkles can be suppressed.
[0026] Based on Figure 3 the mechanism of this material flow will be described. Figure 3 is a diagram for explaining the material flow during the forming process of the CC part enclosed by a dashed line in Figure 2 , showing the state of top view observation and side view observation Figure 2 . In addition, in Figure 3 , the thin dashed line is the outer edge of the blank before forming, the thick dashed line is the outer edge of the intermediate formed part 15, and the solid line is the outer edge of the flange part 5 in the target shape. The points A to E and A' to E' in the figure are related to Figure 7The points shown are the same points. That is, point A in the figure is the R end point of the curved portion in the blank, and is the front end position of the torsion-shaped portion 17. Point B is the point corresponding to the R end point of one side of the blank portion where the existing shrink flange deformation occurs, and point B' is the intersection point of the line perpendicular to the end edge of the torsion-shaped portion 17 from point B in the top view and the end edge of the torsion-shaped portion 17. Point D is the R end point of the curved portion in the blank, and point D' is the intersection point of the line perpendicular to the end edge of the target shape from point D in the top view and the end edge of the target shape.
[0027] Due to the shrink flange deformation, the distance from point B' to point D' is shorter than the distance from point B to point D (B'D' < BD), and wrinkles are likely to occur in the flange portion 5 formed on the convex edge portion 11a due to the remaining material. On the other hand, when observing three-dimensionally, the distance from point A to point B' is longer than the distance from point A to point B (AB' > AB), so the material is stretched toward point A and flows deviating from "substantially perpendicular to the ridge line". Therefore, compared with the material flow of the arrow in the existing Figure 7 wrinkle generation area, the material flow shown by the arrow closer to point A is generated. Through this material flow, the remaining material in the shrink flange deformation formed in the first forming process S1 is alleviated, and the generation of wrinkles can be suppressed. Figure 3
[0028] <Second Forming Process>
[0029] The second forming process S3 is a process of forming the torsion-shaped portion 17 of the intermediate formed part 15 formed in the first forming process S1 into the flange portion 5 and forming the flange portion 5 in the concave edge portion 11b to form the target shape. During the forming process of the second forming process S3, as shown by the arrow in Figure 4 , by retracting and absorbing the torsion of the torsion-shaped portion 17 that has absorbed the Figure 2 material surplus, material inflow is generated toward the extended flange deformation portion using the remaining material. Therefore, the material shortage in the extended flange deformation portion is alleviated, and the generation of cracks can be suppressed.
[0030] Based on Figure 5 to explain the mechanism of generating this material flow. Figure 5 Is a diagram for explaining the material flow during the forming process of the DD portion enclosed by a dotted line in Figure 4 , showing the states of top view observation and side view observation Figure 4 . In addition, in Figure 5 ] , the thin dotted line is the end edge of the blank before forming, the thick dotted line is the end edge of the torsion-shaped portion 17, and the solid line is the end edge of the flange portion 5 in the target shape.
[0031] In addition, points A to E and points A' to E' in the figure are related to Figure 7 ,Figure 3 The points shown are the same points. That is, point A' in the figure is the intersection point of the line perpendicular to the edge line of the target shape from point A in the top view and the target shape. Point E is the point corresponding to the R end of one side of the blank part where the existing stretching flange deformation occurs, and point E' is the intersection point of the line perpendicular to the end edge of the target shape from point E in the top view and the end edge of the target shape. Due to the stretching flange deformation, the distance from point A' to point E' is longer than the distance from point A to point E (A'E' > AE), and cracks are likely to occur in the flange part 5 formed in the concave edge part 11b due to insufficient material. On the other hand, when observed three-dimensionally, the distance from point D' to point E' is shorter than the distance from point D' to point E (D'E' < D'E'), so the material is pressed toward the A' side and flows deviating from "substantially perpendicular to the edge line". Therefore, compared with the material flow indicated by the arrow in the crack generation area of the existing Figure 7 material flow indicated by the arrow, the material flow indicated by the arrow closer to point A' is generated. Through this material flow, the material shortage in the stretching flange deformation formed in the second forming process S3 is alleviated, and the generation of cracks can be suppressed. Figure 5 As described above, in the present embodiment, in the first forming process S1, by first forming only the part that becomes the shrinkage flange deformation, a torsional shape part 17 that promotes the flow of the material toward the part that becomes the stretching flange deformation is formed in this forming. Moreover, in the second forming process S3, by forming the part that becomes the stretching flange deformation, the material shortage due to the stretching flange deformation is suppressed by the material flow from the torsional shape part 17, and the target shape is formed.
[0032] In this way, by dispersing the strain in the dangerous part where stretching flange cracks are generated and the dangerous part where shrinkage flange wrinkles are generated, in the first forming process S1, the generation of wrinkles caused by the shrinkage flange deformation is suppressed, and in the second forming process S3, the generation of cracks caused by the stretching flange deformation is suppressed, and the generation of wrinkles and cracks can be suppressed throughout the process.
[0033] In addition, the first forming process and the second forming process of the present invention can also be formed by different molds. Or, the first forming process and the second forming process can also be performed by one mold.
[0034]
Example
[0035] In order to confirm the effect of the present invention,
[0036] Figure 6 The sliding door rail component shown was stamped into the target shape. The material was a steel sheet with a tensile strength of 1180 MPa grade and a plate thickness of 1.4 mm. First, as a comparative example, without forming the intermediate formed part 15, the target shape was formed in one process, and stamping was performed by pad forming using a pressure pad to press the top plate portion. Next, as an embodiment of the present invention, a first forming process S1 for forming only the shrink flange deformed part of the intermediate formed part 15 described in the embodiment and a second forming process S3 for forming the intermediate formed part 15 into the target shape were performed, and in any of the forming processes, stamping was performed by pad forming using a pressure pad to press the top plate portion.
[0037] In the case of the comparative example, wrinkles were generated at the a part shown in Figure 6 and cracks were generated at the b part, and the target shape could not be obtained. On the other hand, in the embodiment of the present invention, neither cracks nor wrinkles were generated in the flange portion 5, and a high-quality stamped part could be obtained. From the above, it was shown that the present invention is effective in suppressing stretch flange cracks and shrink flange wrinkles when forming a stamped part in which the top plate portion 3 has unevenness in the in-plane direction.
[0038] Industrial applicability
[0039] According to the present invention, it is possible to provide a stamping method that can also be applied to a stamped part in which wrinkles and cracks are generated in the flange itself and can simultaneously suppress the wrinkles and cracks generated in the flange.
[0040] Explanation of reference numerals
[0041] 1... Stamped part; 3... Top plate portion; 5... Flange portion; 7... Protruding portion; 9... Concave portion; 11... Concave-convex edge portion; 11a... Convex edge portion; 11b... Concave edge portion; 11c... Connecting edge portion; 13... Metal plate; 15... Intermediate formed part; 17... Twisted shape portion.
Claims
1. A stamping forming method for forming a stamped forming part, the stamped forming part having: a top plate part with a concavo-convex edge part in which a convex edge part and a concave edge part are continuous via a connecting edge part, the convex edge part protruding outward in the in-plane direction, and the concave edge part being recessed inward in the in-plane direction; and a flange part formed continuously with the concavo-convex edge part in the top plate part. The stamping forming method is characterized by comprising: a first forming process in which an intermediate formed part is formed, the intermediate formed part having a flange part formed in the convex edge part and becoming a shrink flange deformation, and a torsion-shaped part that is continuous with the flange part and is formed in the connecting edge part and has a shape twisted toward the flat concave edge part; and a second forming process in which the torsion of the torsion-shaped part is reversed to form a flange part and a flange part that becomes an expansion flange deformation is formed in the concave edge part to form the intermediate formed part formed in the first forming process into a target shape.
2. The stamping forming method according to claim 1, wherein the first forming process and the second forming process are formed by different dies.
3. The stamping forming method according to claim 1, wherein the first forming process and the second forming process are performed by one die.
Citation Information
Patent Citations
Superconductive electromagnet device
JP1985032374A
Stretch flange forming tool and stretch flange forming method employing same, and member with stretch flange
WO2020026356A1