CN107921504B - Method for manufacturing stretch flange formed part - Google Patents
Method for manufacturing stretch flange formed part Download PDFInfo
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- CN107921504B CN107921504B CN201680049697.9A CN201680049697A CN107921504B CN 107921504 B CN107921504 B CN 107921504B CN 201680049697 A CN201680049697 A CN 201680049697A CN 107921504 B CN107921504 B CN 107921504B
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- flange
- bent
- outer peripheral
- peripheral edge
- top plate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D19/00—Flanging or other edge treatment, e.g. of tubes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D19/00—Flanging or other edge treatment, e.g. of tubes
- B21D19/08—Flanging or other edge treatment, e.g. of tubes by single or successive action of pressing tools, e.g. vice jaws
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/20—Deep-drawing
- B21D22/26—Deep-drawing for making peculiarly, e.g. irregularly, shaped articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D53/00—Making other particular articles
- B21D53/88—Making other particular articles other parts for vehicles, e.g. cowlings, mudguards
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
- Bending Of Plates, Rods, And Pipes (AREA)
- Punching Or Piercing (AREA)
Abstract
A stretch-flange-formed part produced in association with stretch-flange forming is produced with a low forming load while suppressing stretch-flange cracking. The method for manufacturing a stretch flange formed part includes: a top plate (3) having a first concave outer peripheral edge (3 a); a flange portion (7) which is connected to the vertical wall portion (5), is bent toward the top plate portion (3), and has a second concave outer peripheral edge portion (7 a). The method comprises the following steps: a first step of forming a bent portion (8) on the outer side of a position of the blank where the flange portion (7) is to be formed, wherein a ridge line (9) of the bent portion (8) extends along a second concave outer peripheral edge portion (7a) and is bent in the plate thickness direction; a second step of fixing the position of the top plate (3) after the first step and bending the vertical wall portion (5) and the flange portion (7); and a third step of trimming the outer portion of the flange portion (7).
Description
Technical Field
The present invention relates to a technology for manufacturing a stretch flange formed part in which a flange portion is manufactured in association with stretch flange forming by providing a top plate portion with a concave outer peripheral edge portion in which a part of an outer peripheral edge portion is concavely curved inward. Examples of such a stretch-flange-formed part include a press-formed part used as a body frame part of an automobile, for example, and a part having an L-shaped portion or a T-shaped portion in a plan view. The present invention is particularly suitable for a case where an ultra-high-strength material of 980MPa or more is used as a raw material and is manufactured by press forming.
Background
When a component having an L-shaped portion or a T-shaped portion (see fig. 6 and 7) such as a front pillar reinforcement or a center pillar reinforcement, which is a vehicle body frame component of an automobile, is manufactured by press forming from a flat plate-shaped metal plate (blank), drawing or bending is generally used.
Drawing is a method of drawing a metal plate by bringing the distance between a punch and a die close to each other while pressing the periphery of the metal plate with the die and a blank holder, generally using a die including the punch, the die, and the blank holder. The bending is generally performed by using a die including a punch, a spacer, and a die, and the bending is performed by relatively moving the die while a metal plate is sandwiched between the punch and the spacer.
When a bent portion such as an L-shaped portion or a T-shaped portion having a sharply bent shape is formed only by drawing as described above, the higher the vertical wall portion is, the more likely cracks or wrinkles are generated. In particular, in recent years, the strength of a metal sheet as a molding material for an automobile body tends to be increased more and more in order to improve the safety and reduce the weight of the automobile body. Such a high-strength metal sheet cannot expect ductility as in the case of a conventional soft steel sheet, and therefore is important for preventing cracking and wrinkling during press forming.
The portion which is particularly likely to be broken by press forming is a stretch flange forming portion of the bent portion. In this portion, the material flows into the deformation portion while the material end surface is extended in the circumferential direction during the drawing.
On the other hand, there is a technique described in patent document 1. In the technique described in patent document 1, when a part having an L-shape is press-formed, a vertical wall portion and a flange portion are formed while sliding a part of a metal material on a portion of a die corresponding to a top plate portion.
Patent document 1 describes the following: since the portion of the L-shaped portion corresponding to the lower side portion of the L is drawn in toward the vertical wall portion, excessive tension is reduced in the flange portion, and the occurrence of cracking can be prevented (see paragraph No. 0009 of patent document 1).
Prior art documents
Patent document
Patent document 1: japanese patent laid-open No. 2012 and 24536
Disclosure of Invention
Problems to be solved by the invention
However, in patent document 1, since the metal material is slid at a portion corresponding to a part of the top plate portion, a portion where stress concentrates is generated at an end surface of the metal material. As a result, in patent document 1, in addition to the tensile flange fracture at the bent portion, fracture of the end face is also likely to occur. Therefore, the method of patent document 1 is difficult to be applied to a high-strength steel sheet.
Further, since the forming load is high, when it is intended to produce a raw material of an ultra-high strength material of 980MPa or more by drawing only, there is a possibility that the load of the press machine is insufficient in drawing.
The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a stretch flange formed part, which can suppress the rupture of a stretch flange and can be manufactured with a low forming load, from a stretch flange formed part manufactured by stretch flange forming.
Means for solving the problems
In order to solve the problem, a method of manufacturing a stretch flange formed part according to an aspect of the present invention is a method of manufacturing a stretch flange formed part, the stretch flange formed part including: a top plate portion having a concave outer peripheral edge portion in which a part of an outer peripheral edge is curved so as to be recessed inward; a vertical wall portion connected to the concave outer peripheral edge portion of the top plate portion; and a flange portion connected to the vertical wall portion and bent toward the top plate portion, wherein the method for manufacturing a stretch-flange-formed component includes: a first step of forming a bent portion in the blank at a position outside a position to be the flange portion, a ridge line of the bent portion extending along a position to be an outer peripheral edge portion of the flange portion and being bent in a plate thickness direction; a second step of fixing a position to be the top plate portion and bending the vertical wall portion and the flange portion after the first step; and a third step of trimming a portion outside the flange portion after the second step.
Effects of the invention
According to the aspect of the present invention, since the bent portion is provided in advance so as to surround the outer peripheral edge portion of the flange portion where the stretch flange breakage is likely to occur in the first step, even if an ultra-high strength material having a strength level of 980MPa or more is used, the stretch flange breakage at the time of the bending in the second step can be suppressed.
In the aspect of the present invention, the vertical wall portion is formed by bending, not by drawing, and therefore can be manufactured with a low forming load.
In view of the above, according to the aspect of the present invention, even when a stretch flange formed part is produced from an ultra-high strength material having a strength level of 980MPa or more in association with stretch flange forming, it is possible to produce the stretch flange formed part with a low forming load while suppressing the stretch flange from breaking.
Here, the flange portion is connected to the first concave outer peripheral edge portion of the top plate portion via the vertical wall, and is bent toward the top plate portion side with respect to the vertical wall portion, and therefore, stretch flange forming is performed at the time of manufacturing by press forming.
In addition, since the blank sheet (blank) before press forming as a forming material is generally formed by punching or laser processing, burrs, minute flaws, and the like remain on the end face of the material, and local stress concentration is likely to occur when deformation is applied. Therefore, a crack called a tensile flange crack is generated in the material end face during the forming, and in the case of an ultra-high strength material (a high strength steel sheet having a strength of 980MPa or more), the crack rapidly propagates and a large crack is easily generated.
As a measure against the stretch flange breakage, there is also a method of preventing stress concentration by uniformly finishing the end surface by machining or the like, but in the case of press forming a mass-produced product, it is necessary to machine the end surface for each product.
In the aspect of the present invention, the outer portion of the flange portion is trimmed after the second step to form the outer peripheral edge of the flange portion, and the bent portion provided to suppress the breakage of the stretch flange is removed.
Drawings
Fig. 1 is a perspective view illustrating an example of a stretch flange formed part according to an embodiment of the present invention.
Fig. 2 is a perspective view illustrating a blank with a bent shape portion according to an embodiment of the present invention.
Fig. 3 is a schematic view showing an example of the bent shape portion according to the embodiment of the present invention.
Fig. 4 is a perspective view including a partial cross section of a mold used in the second step according to the embodiment of the present invention.
Fig. 5 is an explanatory diagram of a second step according to the embodiment of the present invention.
FIG. 6 is a view showing an A column.
Fig. 7 is a view showing a center pillar.
Detailed Description
Next, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, the following case is taken as an example for explanation: a stretch-flange-formed part having a portion to be a stretch-flange-formed portion is manufactured by using an ultra-high strength material of 980MPa or more as a raw plate (blank) before press forming. The production method of the present invention can be applied even to a raw material made of a metal plate having a strength of 980MPa or less.
The flange-formed part having a portion to be a stretch-flange-formed portion includes, for example, an a-pillar (see fig. 6) or a center pillar (see fig. 7).
In the following description, a portion including a portion to be a stretch flange formed portion in a stretch flange formed part is focused on, and only this portion is illustrated in each drawing. This portion is referred to as a "stretch flange forming portion 1". In the mold, only the portion for molding the portion is shown. Of course, other portions may be formed at the same time.
As shown in fig. 1, the stretch flange molding portion 1 manufactured by the manufacturing method of the present embodiment includes: a top plate 3 having a concave outer peripheral edge portion 3a in which a part of an outer peripheral edge is curved so as to be recessed inward; a vertical wall portion 5 formed along the concave outer peripheral edge portion 3a of the top plate portion 3; and a flange portion 7 having a concave outer peripheral edge portion 7a which is connected to the vertical wall portion 5, bent toward the top plate portion 3 side, and in which a part of the outer peripheral edge is bent so as to be recessed inward. The flange portion 7 is a portion to be formed by stretch flange forming at the time of press forming. The outer peripheral edge of the flange portion 7 does not need to have a concavely curved shape, but is generally formed to have a shape along the concave outer peripheral edge portion 3 a.
Here, in the present embodiment, the concave outer peripheral edge portion 3a of the top plate portion 3 is also referred to as a first concave outer peripheral edge portion 3a, and the concave outer peripheral edge portion 7a of the flange portion 7 is also referred to as a second concave outer peripheral edge portion 7 a. The contour shape of the first concave outer peripheral edge portion 3a and the contour shape of the second concave outer peripheral edge portion 7a are generally the same or similar contour shapes. Of course, the curvature of the contour of the first concave outer peripheral edge portion 3a may be different from the curvature of the contour of the second concave outer peripheral edge portion 7 a.
Here, the curved curve does not need to have a constant curvature, and preferably has no steep curvature portion having a steep curvature in the extending direction thereof.
The method of manufacturing a stretch-flange-formed part according to the present embodiment includes three steps, i.e., a first step, a second step, and a third step, and performs forming in this order.
In the first step, a bent portion 8 is provided to an outer peripheral portion of a flat plate-like raw plate (blank) before press forming, the outer peripheral portion being a position of the flange portion 7. That is, the first step is a step of manufacturing the blank with the bent shape portion shown in fig. 2.
In fig. 2, the raw material portion outside the bent portion 8 is omitted, and the position of the second concave outer peripheral edge portion 7a is illustrated by a one-dot chain line. In the other figures, the raw material portion outside the bent portion 8 is also appropriately omitted for the convenience of observation.
In the second step, the first concave outer peripheral edge portion 3a of the top plate portion 3 is formed, and the vertical wall portion 5 and the flange portion 7 are formed by bending along the first concave outer peripheral edge portion 3 a. That is, the second step is a step of using the blank with the bent shape portion as an intermediate component.
In the third step, the bent shape portion 8 is trimmed from the intermediate part. That is, the third step is a step of forming the outer peripheral edge of the flange portion 7 as the stretch flange formed part.
The respective steps will be described in detail below.
[ first step ]
In the first step, as shown in fig. 2, a bent portion 8 is formed in a flat plate-like raw plate (blank) before press forming, at a position closer to the outer periphery than a position to be the flange portion 7. The bent portion 8 is formed by extending the ridge line 9 along the second concave outer peripheral edge portion 7a and bending it in the plate thickness direction. The bent portion 8 of the present embodiment is formed of, for example, a stepped portion shape bent in the plate thickness direction.
The bent shape portion 8 may be formed by press forming using a die and a punch, or may be formed by another processing method.
The height of the step (the protruding height in the plate thickness direction) of the bent portion 8 to be formed is preferably 3mm to 10 mm.
Fig. 2 illustrates a case where the bent portion 8 is formed so that the ridge line 9 extends parallel or substantially parallel to the second concave outer peripheral edge portion 7a or the first concave outer peripheral edge portion 3a along the second concave outer peripheral edge portion 7 a. However, the bent portion 8 may not extend parallel or substantially parallel to the second concave outer peripheral edge portion 7a or the first concave outer peripheral edge portion 3a, but may extend in parallel or substantially parallel thereto. The bent portion 8 may be formed intermittently along the second concave outer peripheral edge portion 7 a. The bent portion 8 may not be formed so that the ridge line 9 extends along the entire circumference of the second concave outer peripheral edge portion 7 a. The bent portion 8 may be formed such that the ridge line 9 extends only along a portion where the curvature of the curve in the first concave outer peripheral edge portion 3a is large, that is, a portion where the stretch flange is expected to be broken by a forming analysis or the like, and a vicinity continuing to the portion.
Another example of the shape of the bent shape portion 8 is shown in fig. 3. In fig. 3, the bent shape portion 8 is bent so as to protrude downward, but the bent shape portion 8 may be bent in the plate thickness direction so as to protrude upward.
Here, in the first step, the bent portion 8 may be formed and a position to be the top plate 3 may be subjected to press working to form a concave-convex shape for reinforcement or the like provided to the top plate of the stretch flange formed part as shown in fig. 6 or 7. However, the shape of the irregularities formed at the position to become the top plate 3 may not be the same as the shape given to the top plate of the final product, but is preferably a shape close to the shape given to the top plate 3 of the final product. The uneven shape may be a shape formed only in a part of the shape given to the top plate 3 of the final product.
When the concave-convex shape is formed at the position to be the top plate portion 3 in the first step, a shape corresponding to the concave-convex shape may be provided in advance to the surface of the second step where the position to be the top plate portion 3 is sandwiched by the mold. In this case, the uneven shape provided in the first step has the functions of positioning and preventing positional deviation when the blank with the bent shape portion is set in the die in the second step.
[ second Process ]
The second step is a step of bending the blank with the bent portion, which is formed in the first step and to which the bent portion 8 shown in fig. 2 is applied, into an intermediate component.
In the second step, the vertical wall portion 5 is bent by relatively moving the die 32 along the punch 30 while the top plate portion 3 of the blank with the bent portion formed in the first step is sandwiched between the punch 30 and the spacer 31, and the flange portion 7 is bent toward the top plate portion 3.
< mold for second Process >
The second-step mold used in the second step will be described with reference to fig. 4. Fig. 4 shows a state in which a part of the vertical wall portion 5 is formed in the second step in order to understand the position of the first concave outer peripheral edge portion 3 a.
In the following description, the bent portion 8 is bent so as to protrude upward.
As shown in fig. 4, the second step mold includes: a punch 30 constituting a lower die; a die 32 constituting an upper die; and a spacer 31 for pressing a portion of the blank with the bent portion corresponding to the top plate portion 3.
< punch >
The punch 30 has a raised portion 30A for top plate portion clamping and a punch extension portion 30B. The punch extension portion 30B may be separate from the raised portion 30A. The rising portion 30A for top plate portion nipping becomes a first punch, and the punch extension portion 30B becomes a second punch. The punch extension portion 30B has a flange facing surface 30A connected to the lower end portion of the rising portion 30A and capable of facing the formation position of at least the flange portion 7 of the blank from below.
The upper surface of the rising portion 30A serves as a pressing surface for pressing the top plate portion 3 of the material to be molded in cooperation with the spacer 31.
The side surface 30b of the rising portion 30A is formed into a curved surface having the same curvature as the first concave outer peripheral edge portion 3a, and is formed into the shape of the forming vertical wall portion 5 in the stretch flange forming portion. That is, the height of the side surface of the rising portion 30A is set to be the same as the height of the vertical wall portion 5.
< liner >
The spacer 31 is provided so as to be capable of approaching and separating from the upper surface of the rising portion 30A of the punch 30, and is capable of nipping a portion corresponding to the top plate portion 3 of the blank with the bent portion in cooperation with the upper surface of the rising portion 30A of the punch 30. That is, the spacer 31 has a shape having a lower surface along the first concave outer peripheral edge portion 3a of the top plate 3, and can sandwich at least a portion of the top plate 3 along the first concave outer peripheral edge portion 3a side together with the punch 30.
The position of the spacer 31 on the first concave outer peripheral edge portion 3a side is set back from the side surface 30b of the rising portion 30A of the punch 30 in a plan view as shown in fig. 4. Therefore, as shown in fig. 4, when the portion corresponding to the top plate portion 3 is sandwiched between the upper surface of the rising portion 30A of the punch 30 and the pad 31, the portion corresponding to the top plate portion 3 is exposed upward from the first concave outer peripheral edge portion 3a side.
< die >
The punch-side surface of the die 32 and the side surface 30b of the rising portion 30A cooperate with each other to form a curved surface for forming the vertical wall portion 5. The punch-side surface of the die 32 has a protruding portion 32a protruding outward (toward the punch 30) formed on the upper side surface thereof. The protruding portion 32a abuts the upper surface of the punch 30 through the material, thereby restricting further downward movement of the die 32. That is, the limit position is a position of the forming bottom dead center when the die 32 is lowered. The height of the die side surface from the projecting portion 32a to the lower end position is set to the height of the vertical wall portion 5.
Further, a stepped portion 32b is provided on the lower surface of the die 32 facing the flange portion 7, thereby providing a concave relief portion 32 d. By providing the relief portion 32d, the lower surface of the die 32 is configured not to pinch the bent portion 8, and preferably not to contact the bent portion 8, until the die 32 moves to the forming bottom dead center. The width of the lower surface 32c of the step portion 32b is equal to or less than the width of the flange portion.
In a state where the die 32 is lowered to the position of the forming bottom dead center, a height difference (clearance) between the flange opposing surface 30a of the punch 30 and the bottom surface of the relief portion 32d of the die 32 is set in advance to be equal to or larger than the height of the bent shape portion 8 formed in the bent shape portion-attached blank.
By setting in this manner, the bent portion 8 is disposed in the space (recess) formed by the relief portion 32d of the die 32, and as a result, the bent portion 8 is not restrained or pinched in the bending in the second step. In this way, the portion including the bent portion 8 is freely deformed without being restricted in the bending, and thus, stress concentration on a specific portion of the flange portion is reduced, and the occurrence of cracking can be further prevented.
When the bent portion 8 protrudes toward the flange facing surface 30a of the punch 30, the recessed portion for relief as described above may be provided on the flange facing surface 30 a.
With respect to the second step using the second-step mold configured as described above, the operation of the second-step mold will be described with reference to fig. 5.
Fig. 5(a) shows a state where the top plate portion 3 of the blank with the bent portion is pinched by the punch 30 and the spacer 31, and fig. 5(b) shows a state where the die 32 is relatively moved to the bottom dead center of press forming.
First, as shown in fig. 5(a), the top plate 3 of the blank with the bent portion is placed on the upper surface of the punch 30 and sandwiched between the punch 30 and the spacer 31. The gasket 31 is not disposed over the entire surface of the stretch flange forming portion corresponding to the top plate portion 3, but is disposed slightly inward from the side surface of the punch 30 having a curvature corresponding to the first concave outer peripheral edge portion 3 a.
In this state, the die 32 is relatively moved along the side surface of the punch 30 toward the flange opposing surface 30a to the position of fig. 5(b), whereby the first concave outer peripheral edge portion 3a, the vertical wall portion 5, and the flange portion 7 are bent.
That is, the blank with the bent portion is first bent to form the first concave outer peripheral edge portion 3a by the relative movement of the die 32 in the second step. Next, the portion to be the vertical wall portion 5 is bent and formed from the upper side connected to the first concave outer peripheral edge portion 3a toward the lower side in this order, and the flange portion 7 side of the blank is brought into contact with the flange opposing surface 30a of the punch extension portion 30B, and the boundary portion between the lower end portion of the vertical wall portion 5 and the flange portion 7 is bent and formed. In this way, in the present embodiment, the bending is sequentially and continuously applied from the top plate portion side.
At this time, the portion of the blank with the bent portion (outside the position to be the flange portion) where the bent portion 8 is formed as a stretch flange, and a tensile stress in the peripheral direction acts thereon. However, unlike the end face of the original plate before press forming, the ridge line 9 of the bent portion 8 is continuous in the circumferential direction, and therefore, there is no starting point of fracture and fracture is difficult to occur. Further, since the ridge line 9 of the bent portion 8 is continuous in the circumferential direction, stress concentration is not concentrated at this portion and uniform tensile stress is applied, and therefore, from this point of view, cracking is less likely to occur in the tensile flange portion.
Further, since the bent portion 8 of the present embodiment extends along the second concave outer peripheral edge portion 7a in a plan view, the tensile stress acting on the bent portion 8 can be further uniformized.
Further, since the predetermined bent shape portion 8 is formed at least in the vicinity of the bent portion of the flange portion to be stretch-formed in the first step, even when the portion to be the second concave outer peripheral edge portion 7a is subjected to the stretch-flange deformation in the second step, the strain is easily dispersed due to the shape rigidity of the bent shape portion 8, and the strain can be prevented from concentrating on the portion to be the second concave outer peripheral edge portion 7 a.
Further, by forming the predetermined bent portion 8 in the first step, when the second concave outer peripheral edge portion 7a is subjected to stretch flange deformation in the second step, the portion of the bent portion 8 that becomes the second concave outer peripheral edge portion 7a is flattened at a constant height, and thus a linear length difference can be obtained. Therefore, strong tensile stress in the peripheral direction is less likely to act on the second concave outer peripheral edge portion 7 a.
As described above, by making the tensile stress applied to the portion to be the second concave outer peripheral edge portion 7a uniform, the stress after the uniformity is applied to the outer end surface of the bent shape portion 8, and the stress concentration can be alleviated even if burrs, minute flaws, or the like remain on the end surface, and the fracture suppression effect can be exhibited from this point of view.
Further, since the portion including the bent shape portion 8 is not restricted by the die during the molding, it can be freely deformed (moved or retracted) three-dimensionally, and from this point of view, it is also possible to further relax the tensile stress that concentrates on the end face of the part during the molding.
As described above, the intermediate member is formed without cracking.
Here, although the case where the bent shape portion 8 protrudes upward has been described, a concave shape that avoids the bent shape portion may be formed on the punch extension portion 30B side of the punch 30 when the bent shape portion 8 protrudes downward. Further, a concave portion shape for avoiding the bent portion may be formed on both surfaces of the punch extension portion 30B of the punch 30 and the die 32 facing each other.
[ third Process ]
In the third step, a second concave outer peripheral edge portion 7a is formed by trimming a portion of the intermediate member outside the flange portion 7. Thereby, a stretch-flange formed part including the stretch-flange forming portion is manufactured. The trimmed portion includes a bent portion 8.
As described above, in the present embodiment, the bent portion 8 is formed in the first step, the blank with the bent portion is bent and formed into the intermediate component in the second step, and the portion outside the flange portion 7 of the intermediate component is trimmed in the third step, so that even when an ultra-high strength material of 980MPa or more is used as the original plate before press forming, cracking can be suppressed, and a stretch flange formed component including a stretch flange formed portion can be manufactured satisfactorily.
[ Effect of the present embodiment ]
(1) The disclosed device is provided with: a first step of forming a bent portion 8 in the blank at a position outside the flange portion 7, the ridge line 9 of the bent portion 8 extending along the second concave outer peripheral edge portion 7a and being bent in the plate thickness direction; a second step of fixing the position of the top plate 3 after the first step and bending the vertical wall portion 5 and the flange portion 7.
According to this configuration, even if an ultra-high-strength material having a strength level of 980MPa or more is used, the vertical wall portion 5 can be formed by the bending in the second step, and the bent portion 8 is provided in advance along the second concave outer peripheral edge portion 7a where the tensile flange breakage is likely to occur, whereby the tensile flange breakage during the bending in the second step can be suppressed.
Further, the vertical wall portion is not formed by drawing, but formed by bending, and therefore can be manufactured with a low forming load.
In view of the above, according to the present embodiment, even when a stretch flange formed part is produced from an ultra-high strength material having a strength level of 980MPa or more in association with stretch flange forming, it is possible to produce the stretch flange formed part with a low forming load while suppressing the stretch flange from cracking.
(2) The method further includes a third step of trimming the outer portion of the flange portion 7 after the second step.
When a blank sheet (blank) before press forming is trimmed in advance by punching or laser processing, burrs, minute flaws, or the like remain on the material end face, and therefore, local stress concentration is likely to occur when deformation is applied. Therefore, a crack called a tensile flange crack is generated in the material end face during the forming, and in the case of an ultra-high strength material (a high strength steel sheet having a strength of 980MPa or more), the crack rapidly propagates and a large crack is easily generated.
In contrast, the outer portion of the flange portion 7 is trimmed after the second step to form the outer peripheral edge of the flange portion 7, whereby stretch flange cracking is less likely to occur at the end face of the flange portion 7.
(3) Further, the die for the second step is provided with a relief portion 32d for relieving the bent shape portion 8.
According to this configuration, the portion including the bent shape portion 8 is not restricted by the die for the second step during the molding, and therefore, can be freely deformed (moved or retracted) three-dimensionally, and from this point of view, the tensile stress that concentrates on the end face of the part during the molding can be further relaxed.
(4) The height of the step of the bent portion 8 is set to 3mm to 10 mm.
By defining the height of the bent portion 8 within this range, the tensile flange cracking can be more reliably suppressed even if an ultra-high-strength material having a strength level of 980MPa or more is used.
Examples
< inventive example 1>
When a 980MPa grade cold-rolled steel sheet (thickness 1.6mm) was used as a material to manufacture a part having the same shape as the a-pillar shown in fig. 7, the molded article of invention example 1 was manufactured by the manufacturing method shown in the above embodiment through 3 stages of the first step, the second step, and the third step.
That is, in the machining step, as described above, the bent shape portion 8 is formed in the first step. Next, in the second step, the first concave outer peripheral edge portion 3a, the vertical wall portion 5, and the flange portion 7 are continuously bent in this order. Then, as a third step, the outer portion of the flange portion 7 was trimmed to form a molded article according to example 1 of the present invention. The height of the vertical wall portion is set to 100 mm.
On the other hand, the vertical wall portion was formed by drawing in only one step for a component having the same shape as the a-pillar shown in fig. 6, and then the portion outside the flange portion was trimmed to produce the molded article of comparative example 1. In comparative example 1, the bent portion was not provided.
The molded article of example 1 of the present invention was compared with the stretch flange part of the molded article of comparative example 1. As a result of the evaluation, in inventive example 1, no fracture occurred at all in the flange portion of the bent portion, whereas in comparative example 1, fracture occurred in the portion shown in fig. 6.
As described above, the superiority of example 1 of the present invention over comparative example 1 was found in the production of a-pillars.
< inventive example 2>
When a 1180MPa grade cold-rolled steel sheet (thickness 1.6mm) was used as a material to manufacture a part having the same shape as the center pillar shown in fig. 6, the molded article of example 2 of the present invention was manufactured by the manufacturing method shown in the above embodiment through 3 stages of the first step, the second step, and the third step.
That is, in the machining step, as described above, the bent shape portion 8 is formed in the first step. Next, in the second step, the first concave outer peripheral edge portion 3a, the vertical wall portion 5, and the flange portion 7 are continuously bent in this order. Then, as a third step, the outer portion of the flange portion 7 was trimmed to form a molded article of invention example 2. The height of the vertical wall portion is set to 100 mm.
On the other hand, the vertical wall portion was formed by drawing a component having the same shape as the center pillar shown in fig. 7 in one step, and then the outer portion of the flange portion was trimmed to produce the molded article of comparative example 2. In comparative example 2, the bent portion was not provided.
The molded article of example 2 of the present invention was compared with the stretch flange part of the molded article of comparative example 2. As a result of the evaluation, in inventive example 2, no fracture occurred at all in the flange portion of the bent portion, whereas in comparative example 2, fracture occurred in the portion shown in fig. 7.
As described above, the superiority of example 2 of the present invention over comparative example 2 was found in the production of the middle column.
The entire contents of japanese patent application 2015-1699227 (2015-8-28 application) from which this application claims priority are incorporated by reference as part of this disclosure.
While the present invention has been described with reference to a limited number of embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments described above without departing from the scope of the invention.
Description of the reference symbols
1 Flange forming part
3 roof plate part
3a first concave outer peripheral edge portion
5 vertical wall part
7 flange part
7a second concave outer peripheral edge portion
8 bent shape part
9 edge line
30 punch
30A ceiling part for clamping and pressing (first punch)
30B punch extension (second punch)
31 liner
32-die
32d escape.
Claims (3)
1. A method of manufacturing a stretch flange formed part, the method being used for manufacturing the stretch flange formed part, the stretch flange formed part including: a top plate portion having a concave outer peripheral edge portion in which a part of an outer peripheral edge is curved so as to be recessed inward; a vertical wall portion connected to the concave outer peripheral edge portion of the top plate portion; and a flange portion connected to the vertical wall portion and bent toward the top plate portion, characterized in that,
the method comprises the following steps:
a first step of forming a bent portion in the blank at a position outside a position to be the flange portion, a ridge line of the bent portion extending along a position to be an outer peripheral edge portion of the flange portion and being bent in a plate thickness direction, and performing press working on the position to be the top plate portion to form a concave-convex shape while forming the bent portion in the first step;
a second step of fixing a position to be the top plate portion and bending the vertical wall portion and the flange portion after the first step; and
and a third step of trimming a portion outside the flange portion after the second step.
2. The method of manufacturing a stretch-flange-formed part according to claim 1,
in the second step, the die is relatively moved along the punch while the position of the top plate is sandwiched between the punch and the spacer, and thereby the concave outer peripheral edge portion, the vertical wall portion, and the flange portion are continuously bent in this order.
3. The method of manufacturing a stretch-flange-formed part according to claim 1 or 2,
the second step of clamping and fixing a position to be the top plate portion by a punch and a spacer, bending and forming the vertical wall portion and the flange portion by a die, and including a second punch having a surface facing the die with a blank interposed therebetween,
a concave relief portion capable of avoiding contact with the bent shape portion is formed on a surface of the die and the second punch facing the blank and on a surface of the bent shape portion on a protruding side of the bent shape portion caused by at least bending of the bent shape portion.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015169227 | 2015-08-28 | ||
| JP2015-169227 | 2015-08-28 | ||
| PCT/JP2016/074657 WO2017038579A1 (en) | 2015-08-28 | 2016-08-24 | Method for manufacturing stretch-flange-formed component |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107921504A CN107921504A (en) | 2018-04-17 |
| CN107921504B true CN107921504B (en) | 2020-02-07 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201680049697.9A Active CN107921504B (en) | 2015-08-28 | 2016-08-24 | Method for manufacturing stretch flange formed part |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP6156608B1 (en) |
| KR (1) | KR102023541B1 (en) |
| CN (1) | CN107921504B (en) |
| MX (1) | MX367318B (en) |
| WO (1) | WO2017038579A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6908078B2 (en) * | 2018-10-31 | 2021-07-21 | Ｊｆｅスチール株式会社 | Manufacturing method of pressed parts and design method of lower die |
| WO2020144995A1 (en) * | 2019-01-11 | 2020-07-16 | Ｊｆｅスチール株式会社 | Press-molding method, blank member of plate-shaped material, intermediate molded article, method for manufacturing press-molded article, and press-molded article |
| JP6702521B1 (en) * | 2019-01-11 | 2020-06-03 | Ｊｆｅスチール株式会社 | Press molding method, blank material of plate-shaped material, intermediate molded product, method of manufacturing press molded product, and press molded product |
| CN113329829B (en) * | 2019-01-25 | 2022-12-16 | 日本制铁株式会社 | Press forming method and press device |
| CN113365752B (en) * | 2019-01-31 | 2023-01-13 | 杰富意钢铁株式会社 | Method for manufacturing stamped member and method for manufacturing blank |
| MX2022012218A (en) * | 2020-03-31 | 2022-10-27 | Jfe Steel Corp | Method for manufacturing pressed component, method for manufacturing blank material, and steel sheet. |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102791396A (en) * | 2010-05-19 | 2012-11-21 | 新日本制铁株式会社 | Method for press-forming L-shaped components |
| WO2014106932A1 (en) * | 2013-01-07 | 2014-07-10 | 新日鐵住金株式会社 | Press component and method and device for manufacturing same |
| CN107708884A (en) * | 2015-06-16 | 2018-02-16 | 杰富意钢铁株式会社 | The manufacture method of stretch flange profiled part |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002282952A (en) * | 2001-03-22 | 2002-10-02 | Kobe Steel Ltd | Method for press forming aluminum alloy panel molded product |
| JP2012245536A (en) * | 2011-05-26 | 2012-12-13 | Nippon Steel Corp | Method of forming press component |
| JP5965159B2 (en) * | 2012-02-22 | 2016-08-03 | 東プレ株式会社 | Molding method for press parts |
-
2016
- 2016-08-24 JP JP2017505584A patent/JP6156608B1/en active Active
- 2016-08-24 KR KR1020187005408A patent/KR102023541B1/en active IP Right Grant
- 2016-08-24 MX MX2018002445A patent/MX367318B/en active IP Right Grant
- 2016-08-24 WO PCT/JP2016/074657 patent/WO2017038579A1/en active Application Filing
- 2016-08-24 CN CN201680049697.9A patent/CN107921504B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102791396A (en) * | 2010-05-19 | 2012-11-21 | 新日本制铁株式会社 | Method for press-forming L-shaped components |
| WO2014106932A1 (en) * | 2013-01-07 | 2014-07-10 | 新日鐵住金株式会社 | Press component and method and device for manufacturing same |
| CN107708884A (en) * | 2015-06-16 | 2018-02-16 | 杰富意钢铁株式会社 | The manufacture method of stretch flange profiled part |
Also Published As
| Publication number | Publication date |
|---|---|
| MX367318B (en) | 2019-08-15 |
| JP6156608B1 (en) | 2017-07-05 |
| CN107921504A (en) | 2018-04-17 |
| JPWO2017038579A1 (en) | 2017-08-31 |
| MX2018002445A (en) | 2018-06-15 |
| KR20180031764A (en) | 2018-03-28 |
| WO2017038579A1 (en) | 2017-03-09 |
| KR102023541B1 (en) | 2019-09-20 |
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