JP2009285696A - Method of press-forming metallic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of press-forming a metallic sheet, by which a closed section member is easily manufactured from a metallic sheet by using usual press forming equipment. <P>SOLUTION: In order to form the metallic sheet 10 into a member having a square cross section, plastic bending deformation is imparted to a point B, a point C and a point D to be the corner parts of the square by the press forming of one process and also elastic bending deformation is beforehand imparted to a portion between B and C and a portion between C and D to be the sides of the square. After that, when the load is removed, the portion between B and C and the portion between C and D become straight lines by being restored by springback and, the forming is progressed in a direction in which a point A and a point E at both ends of the metallic sheet 10 are approached and the member having the square cross section is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a press forming method for a metal plate.

When manufacturing a member having a shape that is difficult to manufacture with ordinary press forming equipment, such as a closed cross-section member, using a metal plate (for example, a steel plate), it is conventionally divided into a plurality of press working steps Or it has been performed by joining a plurality of members (for example, see Patent Documents 1 to 5).
Japanese Patent Laid-Open No. 03-184585 JP 2001-162324 A Japanese Patent Laid-Open No. 2001-300672 JP 2004-160553 A JP 2006-116552 A

  However, in the conventional manufacturing methods as described in Patent Documents 1 to 5 and the like, complicated processes such as a plurality of pressing processes and a joining of a plurality of members are required.

  The present invention has been made in view of the circumstances as described above, and a closed cross-section member is formed from a metal plate by using a normal press forming facility (a normal press machine and a mold that does not use any complicated mechanism). It is an object of the present invention to provide a press forming method of a metal plate that can be easily manufactured.

  In order to solve the above problems, the present invention has the following features.

  [1] In the press forming method of the metal plate, plastic bending deformation is given to a portion to be permanently deformed by one-step press forming, and the deformation of the metal plate is restored by the springback after unloading. A method for press forming a metal plate, comprising forming a closed cross-section member by applying elastic bending deformation to a portion where the entire metal plate is to be formed.

  In the present invention, it is possible to easily manufacture a closed cross-section member from a metal plate without using a plurality of steps using a normal press forming facility.

  The present invention utilizes a spring back of a metal plate and presses a closed cross-section member from the metal plate in a single step using a normal press forming facility (a normal press machine and a mold that does not use any complicated mechanism). It is manufactured by molding, and plastic bending deformation is given to the part that wants to be permanently deformed, elastic bending deformation is given to a predetermined part, and after the unloading, the elastic bending deformation is given to the part. A metal plate is formed by a spring back so that a closed cross-section member having a desired shape is obtained.

  In the present invention, the “closed cross-section member” means a member having a cross-sectional shape having two or more pairs of faces facing each other. For example, it has a cross-sectional shape as shown in FIG. It is a member. 1 (a) is a member having a square cross section, FIG. 1 (b) is a member having a rectangular cross section, FIG. 1 (c) is a member having a rectangular cross section partially opened, and FIG. 1 (d) is a rectangular partition. It is the member of the inserted cross section.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
In the first embodiment, as shown in FIG. 2, a metal plate (blank) 10 is press-formed in one step using a normal press and a mold (here, punch 11, die 12, pad 13). Thus, a member having a square cross section as shown in FIG.

  That is, as shown in FIGS. 3A to 3E, the metal plate 10 is formed as the punch 11 rises, and when the punch 11 completes the rise, as shown in FIG. The shape is as shown in (f). Note that the punch 11 is omitted in FIGS.

  Accordingly, in FIG. 3F, plastic bending deformation is given to the points B, C, and D that are the corners of the square, and between the BC and the CD that are the sides of the square. Elastic bending deformation is given.

  Then, when unloading from the state of FIG. 3 (f), the BC and CD are restored by a spring back to become a straight line, and the forming proceeds in a direction in which the points A and E at both ends of the metal plate 10 approach each other. To do. As a result, a square cross section is finally obtained as shown in FIG.

  In the above description, the bending angle of the plastic bending deformation applied to the points B, C, and D is set to an angle that anticipates the spring back at the points B, C, and D (for example, 84 °). Further, the bending radius of the elastic bending deformation given between the BC and the CD is appropriately determined so as not to be plastically deformed between the BC and the CD while taking into consideration the bending angle given to the point B or the like.

  Here, about this press molding method, the result confirmed by the finite element method is shown in FIGS. FIG. 4 is a perspective view showing an analysis model at that time, and FIG. 5 shows the shape of the metal plate 10 at the time when the die 12 has completed its lowering. And FIG. 6 is the result of calculating what kind of shape the metal plate 10 becomes after unloading from the shape shown in FIG.

  Here, the metal plate (blank) 10 is a steel plate having a material strength of 1180 MPa, a plate thickness of 1.2 mm, and a plate width of 150 mm, a pad pressure of 10 ton, a friction coefficient of 0.12, and an increase in the punch 11. The speed was 0.5 m / s.

  As a result, the shape shown in FIG. 6 (a) (the shape shown in FIG. 5) is changed to a member having a square cross section as shown in FIGS. 6 (b) and 6 (c). It was confirmed that

  Thus, in this Embodiment 1, the member of a square cross section can be manufactured from the metal plate 10 in one process using a normal press molding equipment.

  Incidentally, the minimum bending radius (elastic limit bending radius) that can be given to the steel sheet within the elastic range is shown in FIG. 7, but the elastic limit bending radius decreases as the yield point YP increases and the plate thickness decreases. .

  FIG. 8 shows the minimum length of one side of the square cross section that can be manufactured by the above-described press molding method. As the yield point YP is higher and the plate thickness is thinner, the minimum length of one side of the square cross section that can be manufactured is shown. It gets shorter.

[Embodiment 2]
In the second embodiment, a metal plate is formed into a complicated closed cross-sectional shape as shown in FIG. 1D by one-step press molding by the same method as in the first embodiment.

  That is, as shown in FIG. 9 (a), the B, C, D, E, and F points serving as corners are subjected to plastic bending deformation at a predetermined bending angle and between the BCs serving as sides. Elastic bending deformation with a predetermined bending radius is given between CD, DE, and EF.

  Then, when unloading is performed in order from the state of FIG. 9A, the BC, CD, DE, and EF spring back to form a straight line, and molding proceeds in a direction in which each part approaches. As a result, a closed cross-sectional shape as shown in FIG. 9B is finally obtained.

  As described above, in the second embodiment, a member having a complicated closed cross-sectional shape can be manufactured from a metal plate in one step using a normal press forming facility.

It is a figure which shows the example of the member of the closed cross-sectional shape shape | molded in this invention. It is explanatory drawing of the press molding equipment used in Embodiment 1 of this invention. It is explanatory drawing of Embodiment 1 of this invention. It is a figure which shows the analysis model regarding Embodiment 1 of this invention. It is explanatory drawing of the analysis model regarding Embodiment 1 of this invention. It is a figure which shows the analysis result regarding Embodiment 1 of this invention. It is a graph which shows the elastic limit bending radius regarding Embodiment 1 of this invention. It is a graph which shows the minimum length of one side regarding Embodiment 1 of this invention. It is explanatory drawing of Embodiment 2 of this invention.

Explanation of symbols

10 Metal plate (blank)
11 Punch 12 Die 13 Pad

Claims (1)

  In the metal sheet press forming method, the plastic bending deformation is applied to the portion to be permanently deformed by one-step press forming, and the deformation of the metal plate is restored by the springback after unloading. A press forming method of a metal plate, characterized in that a closed cross-section member is formed by applying elastic bending deformation to a portion where the forming of the entire plate is desired to proceed.

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