JPH044047B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a bending mold device having punches, dies, etc. used when bending steel plates and the like used as exterior products.

BACKGROUND TECHNOLOGY As shown in FIG. 1, a conventional bending device consists of a punch 1 and a die 2. A workpiece (hereinafter referred to as a plate) 4 is fixed between the die 2 and a pad 3.
The punch 1 slides from above while maintaining a certain clearance C with the die 2, and bends by applying a bending moment. At this time, a natural curved surface 8 was formed on the outer side (hereinafter referred to as an edge) 7 of the formed ridge line after deformation.

Problems to be Solved by the Invention However, as shown in FIG. 2, in the conventional bending process, after applying a bending moment to the workpiece 9 to give it bending deformation, the bending moment is removed.
Due to the elasticity of the material, a springback phenomenon occurs in which the deformation returns to some extent, which affects machining accuracy. In the figure, a indicates the return angle due to spring back. For example, when a mild steel plate with a thickness of 2 mm is bent at right angles by V-bending, the bending radius is 1.0 to 4.0 mm and the bending angle is 1° and 5.0 to 6.0 mm.
This produces a return angle of about 2°. For this reason, a product with an angle slightly larger than the set angle is produced, which affects machining accuracy. Furthermore, as shown in Figure 3, when a plate is bent out of plane along a straight edge, the outer surface side is stretched in a direction perpendicular to the bending line, and the inner surface is shrunk, causing transverse strain and becoming a compound curved surface. This caused warpage and affected machining accuracy. In the figure, h is the amount of warpage.

The present invention solves the above-mentioned conventional drawbacks, and aims to press edges and improve processing accuracy by changing the shape of the mold used for bending.

Means for Solving the Problems In order to solve the above problems, the bending mold device of the present invention has a die having a convex L-shaped cross section with a rounded top, and a workpiece formed between the die and the die. A bending mold device comprising a pad for holding an object in a cantilevered state, and a punch for pressing and bending a portion of the cantilevered workpiece protruding from the die to form an L-shaped product. , the punch has a tip end surface that contacts and presses the protruding workpiece, and a punching process that faces a side surface of the die along the bending direction of the workpiece in order to clamp and press the workpiece with its wall thickness. As an edge press part having a surface and extending from the punching surface to a position facing the top of the die with a wall thickness smaller than the wall thickness of the workpiece to pinch and press the edge of the workpiece. It has an inclined surface of .

Furthermore, the bending mold device of the present invention includes a die having a concave U-shaped cross-sectional shape, and a punch for pinching and pressing a workpiece between the die and the die to form a U-shaped product. In the molding die device, the punch has an outer surface, a tip surface, and the outer surface, which are opposite to the inner surface and bottom surface of the die, respectively, in order to clamp and press the workpiece with its wall thickness. A boundary ridge line having a roundness is provided between the tip surface and the bottom surface of the die, and a boundary ridge line between the outer surface of the punch and the tip surface is located opposite to the boundary ridge line between the outer surface of the punch and the tip surface. The die is provided with a sloped surface as an edge press portion that slopes inward toward the bottom surface of the die so as to clamp and press the edge of the workpiece with a wall thickness smaller than that of the workpiece. be.

Function The present invention provides a part (hereinafter referred to as edge press section) that presses the edge part of the plate material formed outside the bending part at the same time as the bending process when bending the plate material into a U-shape or L-shape. punch with,
A device consisting of a mold such as a die presses the edge from this edge press part, that is, by applying pressure in the thickness direction of the forming part to reduce the plate thickness, the spring back phenomenon caused by bending, the ridge line This makes it possible to eliminate warpage and improve processing accuracy.

Embodiment An embodiment of the present invention will be described below based on FIG. 4. This example shows L bending, and the figure shows the state at the end of pressurization. 10 is punch, 11 is die,
12 is a plate holding pad. When the plate 13 is subjected to conventional bending processing, a naturally curved surface 15 is inevitably formed at the edge portion 14. In this embodiment, since the punch is L-bent, a naturally curved surface 15 is formed on the punch side, so an edge press portion 16 is provided on the punch 10. The edge press section 16 has a flat surface that is in contact with the naturally curved surface 15, and is configured to press vertically. In reality, it is appropriate to bite into the punched surface 17 at an angle of about 45° to about 1/5 to 1/3 of the edge plate _t1 . Then, we designed a punch that would bend the board and press the edges at the same time.

FIG. 5 shows another embodiment of the present invention in U-bending, and shows the state at the end of pressurization. 23
24 is a punch, 24 is a die, and 25 is a workpiece plate. In the case of U-bending, the natural curved surface 27 of the edge 26 is formed on the die side, so the edge press part 2 is attached to the die 24.
8 will be provided. This edge press section 28 may have a flat surface similar to that of the edge press section shown in FIG. U-bending can be seen as the opposite effect of L-bending, and pressure is generated in the edge press section 28 as a reaction force of the punch to compress the natural curved surface of the edge. Note that when a knockout plate is inserted into the bottom of the die, a similar edge press portion may be formed on the knockout plate instead of forming an edge press portion on the die.

As a result of the above, it is possible to eliminate spring back and edge warpage even in L-shaped and U-shaped bending by providing a suitable edge press part to the mold. In this embodiment, bending radii r ₁ and r ₂ were provided at the ridgeline processing portions of the L-bending die and the U-bending punch, respectively, to avoid stress concentration.

Effects of the Invention As described above, the L-shaped and U-shaped bending molds are provided with an edge press part that presses the edge part of the plate, and by pressurizing the natural curved surface that was conventionally formed at the forming ridge line, springs are formed. It can eliminate the back phenomenon and the phenomenon of edge warping, contributing to increasing machining accuracy, and has a great practical effect.

Furthermore, the edges are angled due to the flat edge press section, creating a sharper design than the conventional natural curved surface, which has the additional effect of improving the sense of luxury.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional bending mold device, FIG. 2 is a sectional view showing the spring back phenomenon in conventional bending, and FIG. 3 is a perspective view of a bent product showing warping of the same ridge line. FIG. 4 is a cross-sectional view of a molding die device for L-bending according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view of the same for U-bending according to an embodiment of the present invention. 1, 10, 23... punch, 2, 11, 24...
...Die, 3, 12...Pad, 4, 9, 13, 2
5... Workpiece, 7, 26... Outer part (edge) of forming ridge line, 8, 15, 27... Natural curved surface, 8, 1
6,28... Edge Press Department.

Claims (1)

[Scope of Claims] 1. A die having a convex L-shaped cross section with a rounded top, a pad that holds a workpiece in a cantilevered state between the die, and a pad in the cantilevered state. pressing and bending a portion of the workpiece that protrudes from the die;
A bending mold device comprising a punch for forming an L-shaped article, wherein the punch has a tip surface that presses and bends the protruding workpiece by contacting the protruding workpiece, and a punch that bends the workpiece by its wall thickness. In order to clamp and press, the die has a punching surface facing the side surface along the bending direction of the workpiece, and a punching surface that is thicker than the wall thickness of the workpiece is provided from the punching surface at a position facing the top of the die. A bending mold device characterized in that it has a sloped surface as an edge press portion extending to pinch and press the edge of the workpiece with a small wall thickness. 2. A bending mold device comprising a die having a concave U-shaped cross-sectional shape and a punch for forming a U-shaped article by clamping and pressing a workpiece between the die and the punch, In order to clamp and press the workpiece with its wall thickness, an outer surface and a tip surface facing the inner surface and a bottom surface of the die, respectively, and a roundness between the outer surface and the tip surface are provided. There is a boundary ridge line between the inner surface and the bottom surface of the die, and a wall thickness of the workpiece is located at a position opposite to the boundary ridge line between the outer surface and the tip surface of the punch. A bending mold device characterized in that an inclined surface serving as an edge press section is provided that slopes inward toward the bottom surface of the die so as to press the edge of the workpiece with a thickness smaller than that of the die.