JPS6182929A - Bending method of metallic blank sheet - Google Patents

Abstract

PURPOSE:To simplify the correction of spring back by squashing and extending a bead of excess metal formed previously as well as extending out this bead-line length portion to a bending part. CONSTITUTION:A bead 2 of excess metal, having a cross section of semicircular arcuate shape is previously formed at the bending part of a metallic blank sheet. This projecting part of blank sheet is pressed and bent by lowering a movable die 6 while inserting perpendicularly the bent part into the space between the side faces of a bending die 3 and the movable die 6. Successively, the bead 2 is squashed and extended between the shoulder part of die 3 and the pressing surface 7 of die 6, fitted to the shoulder part by lowering the die 6. Further, a part of blank sheet adjoining to the rear side of bead 2, is bent along the shoulder part to form a bent part. Accordingly, a portion of bead 2 line length is added to the bent part. In this way, a spring back is simply and surely corrected by the behavior of a portion of extended-line length tending to warp inward.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of bending a metal blank into a flange or the like using a press die.

Needless to say, when a metal blank is bent, due to the elasticity of the blank itself, this blank will, for example, move to r of the temporary phase of the tooth diagram. In particular, the larger the bending angle of the bent portion, the greater the degree of springback.However, the occurrence of springback is unavoidable, and it is necessary to correct it by some means.

[Conventional technology]

Conventionally, as a means of correcting the springback, a spring was applied to the molding surface (b) of the mold, for example when the blank plate was bent at the angle shown in the figure (a) to be taken out as a product (a), as shown in Figure 9. This is done by pre-processing an estimated amount (B) that is greater than the bending angle of the product B), but this estimated amount is extremely uncertain, and in the first place, the There is a problem that the above-mentioned processing, including precision, complicates the mold structure and increases the cost of the mold.

[Purpose of the invention]

The present invention eliminates the complicated method of correcting springback on a mold as in the past, and adopts a method of applying bead processing to a blank metal plate and crushing and stretching it, thereby correcting springback. The purpose is to obtain a highly accurate bending angle.

〔Example〕

As shown in Figure 1, an extra bead (2) with a semicircular arc cross section is formed in advance on the bent part of the metal blank (1).
.

The above metal plate (IJ, fang, bend shape as shown in Figure 2) (3)
The bead (2) is clamped between the bending die (3) and the holding die (4) so as to face the arcuate shoulder (5) of the bending die (3). In the state shown in Figure 2 of the spear above, first press the shoulder part (5).
The part of the raw plate that protrudes outward from the movable die (as shown in Figure 3)
6) is pressed and bent by the downward movement of the bending die (3) and the movable die (6), and the die is introduced in an overlapping manner between the sides of the bending die (3) and the movable die (6). As shown in the diagram, the bead (2) has an arc-shaped pressing surface (7) located on the shoulder (5), which matches the shoulder (5) provided on the shoulder.
By this crushing, the line length of the bead is pushed out to the vertical blank part in the state shown in Fig. J above, and the blank part continuing behind the bead is also moved along the shoulder part (5). Since it is bent, this blank part is formed as 7 (81) with a bending angle (R) that corresponds to the bending angle of the shoulder, so that at this bend (8) there is a linear length (2) of the bead. is added.

To explain the above in detail with reference to the explanatory diagram of Fig. 5, the line length (2) of the bead is moved from the end point of the bent part (8) of the blank plate to the fixed point of the straight part, and therefore The bending angle range in (8) is apparently increased to a larger range than the original bending angle range of the bending die.

This means that the line length (2) has a tendency to bend inward from the end point (8) of the bending part (8), while the original bending angle of the mold <o>vr 1. Springback occurs in the bending angle range of the corresponding blank plate. Therefore, this springback, in other words, the outward return force is due to the inward bending behavior due to the wire length (2) above. It will be canceled out.

Therefore, springback is substantially corrected.

[Modified example]

In the above embodiment, the groove of the bead (2) faces downward to the shoulder (5) to crush the bead, but the effect is the same even if the groove faces upward and the bead is crushed. . Also, as shown in the diagram, when the blank plate is bent along a curved line when viewed from above, it is difficult to form a continuous bead, so it is best to add intermittent beads as shown in the diagram. Good too.

〔Effect of the invention〕

As described above, according to the present invention, the complicated method of correcting springback on the conventional mold is stopped, and the bead processing is added to the metal blank, which is then crushed and stretched to reduce the length of the bead line. A predetermined bending angle with corrected springback can be obtained by a simple method of extruding the bent part of the plate to increase its bending range. However, according to this method, by changing the bead height, in other words, by adjusting the bead line length, it is possible to adapt to any bending angle, which is not possible with conventional bending methods of this type. It has excellent features that cannot be expected.0

[Brief explanation of drawings]

Figure 1 is a slope view of a part of the metal blank, Figure 3 is a cross-sectional view of the mold showing the bending process, Figure 3 is an illustration of how springback is bridged, and Figure 6 is The figure is a plan view of a metal blank showing a modified example, Figure 7 is a side view of the same as above, and figures G and D are explanatory views of the conventional example. (1)... Metal plate, (2)... Excess bead, (8
)...Bending part of the raw plate. Patent applicant: Tokyo Press Kogyo Co., Ltd. Figure 1 4.2.4 ' Figure 3 Figure 1 Figure 6 ヱ Figure 8

Claims (1)

[Claims] Excess bead is formed in advance on the bending part of the metal blank, and this bead is crushed and stretched during the bending process of the blank, so that the length of the bead line becomes the bent part of the blank, increasing the bending range. A method for bending a blank metal plate, which is characterized by being able to extrude it in such a way that it bends.