JP5515566B2 - Bent member forming method, bent member and bent member manufacturing method - Google Patents

Description

  The present invention relates to a method of forming a flat plate into a bent member (specifically, a frame member having a bent shape), and in particular, enables formation of a bent member from a high strength steel plate having a tensile strength (TS) of 590 MPa or more. The present invention relates to a forming method, a bent member, and a bent member manufacturing method.

  As a means for obtaining a bent member, conventionally, press molding (hereinafter, referred to as conventional press molding) in which various types of molding methods of drawing, stretching, stretching flange and bending are performed on a single metal plate is performed. Furthermore, a method of bending a cylindrical member (Patent Document 1), a roll forming technique (Patent Document 2), and a bending process using a hollow member (Patent Documents 3 and 4) have been proposed. As an example of reinforcing the bent member, a method of filling a foamed resin (Patent Document 5) has been proposed.

Japanese Patent Laid-Open No. 9-30345 Japanese Patent Application Laid-Open No. 11-129045 JP-A-8-174047 JP 2005-1490 A Japanese Patent Laid-Open No. 11-348813

  Increasing the strength of steel sheets in response to demands for weight reduction leads to a decrease in drawing, overhanging, and stretch flangeability of the steel sheets at the same time, so conventional press forming has problems such as cracks and wrinkles, especially complicated shapes. Accordingly, there has been a case where a bent member cannot be obtained. For example, a single sheet of high strength steel plate with a TS of 590 MPa or more is formed into members 50A and 50B (having XY plan view and bending in the Z-axis direction) constituting the bending member 50 as shown in FIG. 11 by conventional press forming. Then, wrinkles (for example, generated in “wrinkled” portions in the drawing) in the flat portion, and cracks (for example, generated in “broken” portions in the illustrated portion) in the side vertical wall portions and flange portions occur. At this time, it is possible to suppress the occurrence of cracks and wrinkles to some extent by optimizing the molding conditions such as wrinkle holding or changing the part shape. However, with such a method, TS to meet the need for weight reduction Therefore, it can be said that there is a limit to cope with further increase in strength of 980 MPa or more.

  In addition, a method for obtaining a high-strength bent member by bending a cylindrical member or roll forming is disclosed (Patent Documents 1 to 4), but from the viewpoint of process restrictions and material formability. In addition, it is difficult to obtain a complicated bent shape, and there are significant problems in production such as an increase in the number of processes. For example, when a low-strength material is used, a complicated shape can be easily obtained, but since the member strength is insufficient, there is a technique for obtaining a reinforcing effect by filling with a foamed resin (Patent Document 5). It is hard to say that the technology is always useful from the viewpoint of production or recycling.

  That is, in the conventional forming method, when a single sheet of high-strength steel plate is used as a material, it cannot be formed into a desired bent member by integral press molding, or when a single plate of low-strength steel plate is used as a material, However, the strength of the member is not sufficient, and it is necessary to increase the number of parts having a reinforcing effect, resulting in an increase in weight.

The present invention for solving the above problems is as follows.
(Claim 1) A bending member forming method for forming a bent member by forming a flat blank made of a single metal plate, wherein the bent member has a bent contour shape corresponding to the bending in the length direction of the bent member . The blank is folded in a direction perpendicular to the width direction at one or three positions in the width direction so as to have a cross-sectional shape corresponding to a divided portion of the cross-sectional shape of the bending member, or a cross-section L-shaped member or a cross-section L a bending step shall be the member having a flange-shaped ends, bent member molding method and having a bonding step of bonding two or more members obtained by the bending process.
(Claim 2) The bending member forming method according to claim 1, wherein the blank is creased or further cut before the bending step.
(Claim 3) A bending member manufactured by using the bending member forming method according to claim 1 or 2.
(Claim 4) A bending member manufacturing method, wherein a bending member is manufactured using the bending member molding method according to claim 1 or 2.

  According to the present invention, since the material undergoes bending deformation with almost no deformation of the drawing, overhanging, and extension flange, it is possible to perform integral press molding from a single sheet of high-strength steel sheet to a member constituting the bending member. . Furthermore, by reflecting the shape of the bent member as the forming target in the contour shape of the blank, it is possible to easily obtain a member having a high member strength and a complicated bent shape, which has not been obtained conventionally, and reducing the cross-section of the part Higher weight savings can be expected by expanding the space by reducing the thickness of the plate or eliminating the reinforcement member.

Schematic showing an example of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Schematic which shows one example (an example different from the previous example) of an embodiment of the present invention Sectional drawing which shows the example of various bending member cross-sectional shape Schematic showing an example of how to fold Schematic showing an example of a bending member by conventional press molding

  1 to 8 are schematic views showing different examples of embodiments of the present invention. FIGS. 1 and 2 are both examples in which the bending of the bending member 30 in the length direction is a bent line-shaped bending in only one of the two reciprocal directions. Further, in FIG. 1, the cross-sectional size is the member length direction. In FIG. 2, the cross-sectional size changes in the member length direction. 3 and 4 are both examples in which the bending in the length direction of the bending member 30 is a bent line-shaped curve that changes from one of the two opposite directions to the other, and in FIG. The size is constant in the member length direction, and the cross-sectional size is changed in the member length direction in FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are examples in which the bending in the length direction of the bending member 30 is a continuous curved curve in only one of two reciprocal directions (FIG. 7, FIG. 8: an example having a twisted bent cross-sectional shape in the length direction), and the cross-sectional size is constant in the member length direction in FIG. 5, and the cross-sectional size is in the member length direction in FIGS. Has changed.

  In these examples, the two blanks 1 and 2 have the same planar shape, and this planar shape is a side curved contour shape corresponding to the bending in the length direction of the bending member 30 which is a forming target. . Needless to say, the blanks 1 and 2 may be preliminarily provided with shapes such as work holes and beads. In the bending step, the blanks 1 and 2 are bent into a cross-sectional shape corresponding to a divided portion of the cross-sectional shape of the bending member 30 to be members 10 and 20 constituting the bending member 30, respectively. In addition, 1F and 2F are the flange corresponding parts of the blanks 1 and 2, or the flanges of the members 10 and 20, respectively. 1 to 8, broken lines and dotted lines drawn in the shape regions of the blanks 1 and 2 are mountain folds and valley folds, respectively, which are bent portions (convex ridge portions) formed by bending in a bending process. , Concave ridges) are shown. In the bending process of the present invention, the material to be molded is deformed by the bending process so that the molding part of the blank becomes a corresponding folding part of the target member using a mold, and the target shape is deformed. To be molded.

Next, in the joining step, the members 10 and 20 are joined to obtain the bent member 30. As a joining method, any method such as welding, caulking, rivet, or adhesive may be used.
Moreover, although the example shown in FIGS. 1-6 is a shaping | molding example to the member cross-sectional shape shown to Fig.9 (a), this invention is not limited to this, For example, FIG.9 (b) As shown in FIG. 9A, the shape of the member is reversed to the left and right, or the member 20 is bent into the shape of the member having the flange 2F bent as shown in FIG. 9C. Applicable to. The example shown in FIGS. 7 and 8 is an example of forming the member cross-sectional shape shown in FIG.

Moreover, although the example shown in FIGS. 1-6 and FIG. 8 is an example using two blanks of the same plane shape with respect to one bending member, this invention is not limited to this, Even when three or more blanks are used for one bent member, and at least one of the blanks has a different planar shape from the other, it can be obviously applied.
Furthermore, in the present invention, in order to improve the positional accuracy of the bent portion during the bending process, it is preferable to crease the mountain fold and valley fold portions in the blank in advance. It should be noted that the crease is not limited to being applied (continuously) over the entire portion corresponding to the bent portion, and may be applied to only a part of the portion (intermittently) according to circumstances. Good. Coining or the like can be preferably used as the processing method for forming the crease. Moreover, the method of transferring the uneven | corrugated shape given to the roll surface to the surface of material continuously is also mentioned. As a preferred form of such folds, a V-groove as shown in FIG. 10 (d) is provided in the form of a line (a), a broken line (b), a dotted line (c), or a combination of these. Is mentioned. Here, the depth of the V-groove is preferably 20% or less of the metal plate thickness (abbreviated plate thickness). When the depth of the V-groove exceeds 20% of the plate thickness, there is a possibility that the strength of the member required for an automobile frame member or the like may be reduced, or a crack may be generated in the bent portion. This is because it is not easy to deepen the groove itself, and there are serious problems in production and cost.

The shape of the groove is not limited to the V shape (not limited to the V groove illustrated in FIG. 10D), and may be various concave shapes such as a U shape. Moreover, when taking the curvature radius of a bending part large, you may provide a several groove | channel in parallel.
In addition, it is expected that there is a high risk of cracking or wrinkling due to local excessive elongation or shrinkage deformation processing during bending (for example, excessive elongation or shrinkage flange processing at the flange-corresponding portion of the blank). In the case where there are a plurality of local areas that are likely to be received, it is preferable to make a cut in such a local area in advance to prevent the occurrence of cracks or wrinkles more reliably.

  A blank made of a thin steel plate (material symbols A, B, C) having the thickness and tensile properties (yield strength YS, tensile strength TS, elongation El) shown in Table 1 is bent by the forming method shown in Table 2. The shape of the obtained bent member was visually observed to evaluate the forming method. As a result, as shown in Table 2, in the comparative example by the conventional press molding, wrinkles were generated in the “wrinkled” portion shown in FIG. Then, there was no generation of cracks and wrinkles, and a bent member almost according to the target shape was obtained.

  As shown in FIG. 10, a blank made of a thin steel plate (material symbols A, B, C) having the thickness and tensile properties (yield strength YS, tensile strength TS, elongation El) shown in Table 1 is preliminarily shown in FIG. After forming a crease composed of a straight, broken or dotted V-groove (the depth of the V-groove is shown in Table 3), it is formed into a bending member by the molding method shown in Table 3, and the obtained bending member The shape was visually observed to evaluate the molding method. As a result, as shown in Table 3, in the example of the present invention, cracks and wrinkles did not occur, and the degree of coincidence with the target shape was better than that of the example of the present invention in Example 1 (the dimensional accuracy was good). A bending member was obtained.

DESCRIPTION OF SYMBOLS 1, 2 Blank 1F, 2F A flange or a flange corresponding part 10, 20 The member which comprises the bending member which concerns on this invention 30 The bending member which concerns on this invention (molding target)
50 Bending member by conventional press molding (additional signs A and B are members constituting the bending member 50)

Claims (4)

A bending member forming method for obtaining a bent member by forming a flat blank made of a single metal plate, wherein the bent plate is formed into a bent contour shape corresponding to the bending in the length direction of the bent member. It is bent at one or three positions in the width direction in a direction perpendicular to the width direction so as to correspond to the divided portion of the cross section of the member. a bending step shall be the member having a flange bend member molding method and having a bonding step of bonding two or more members obtained by the bending process.   The bending member forming method according to claim 1, wherein the blank is folded or further cut before the bending step.   The bending member manufactured using the bending member shaping | molding method described in Claim 1 or 2. A bending member manufacturing method, wherein the bending member is manufactured using the bending member forming method according to claim 1.

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