JPH07299519A - Method for bending metal plate and device therefor - Google Patents

Abstract

PURPOSE:To bend a metal plate to be worked into an arbitrary angle shallower than the angle formed by the pressing piston faces of a die with high accuracy. CONSTITUTION:An elastic body 13 is held with a holding metal hardware 22, the metal plate W to be worked is put on the horizontal supporting face 14 of the elastic body 13 and, by pressurizing this metal plate W between an upper die 11 having front and rear inclined angles that are asymmetrical of the pressing piston faces 9, 10 At the tip and the elastic body 13, the metal plate W to be worked is bent. The holding metal hardware 22 has supporting walls 24, 25, 26 for supporting the bottom, front and rear surfaces of the elastic body 13 and the rear supporting wall 26 is projected to the position of the horizontal supporting face 14 of the elastic body 13. The pressurizing force to the metal plate W to be worked with the die 11 is supported at the top of the rear wall 26 on the backside and at the horizontal supporting face 14 of the elastic body 13 on the front side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for bending a plate material to be processed such as a metal plate by using a mold, and more particularly, the present invention relates to The present invention relates to a plate material bending method and a device for pressing and bending a plate material to be processed.

[0002]

2. Description of the Related Art Generally, a press brake is used for bending a metal plate. This press brake has a structure in which the lower mold is installed on the table and the upper mold is attached to the lower end of the ram, and the upper mold is lowered by pedal operation and supported on the lower mold. The plate material to be processed is pressed and pushed into the V-shaped groove of the lower mold by a predetermined amount to bend the plate material to a desired bending angle. In order to obtain a U-shaped molded article 1 as shown in FIG. 5, the first bent portion of the plate material to be processed is bent at a right angle to form the first bent portion 2a, and then the second bent portion is formed. The points are bent at right angles in the same direction to form the second bent portion 2b.

A normal upper mold has a straight length, but a deep U-shaped molded product 1 in which the width B of both side pieces 3 and 4 is sufficiently larger than the width A of the intermediate piece 5. To get
As shown in FIG. 6, an upper die 6 having a special shape in which the tip portion extends obliquely downward is used. This upper die 6 is the second
When the bent portion 2b is formed, the side piece 3 that has already been bent does not collide with the side surface of the upper mold 6. The tip of the upper die 6 is sharp, and the pressing surfaces 9 and 10 before and after it are
Is 90 degrees, and the V-shaped groove 8 on the upper surface of the lower mold 7
It matches the opening angle of. Front and rear stamping surfaces 9, 10
The inclination angles θ1 and θ2 (the inclination angle of the groove bottom surface of the V-shaped groove 8) with respect to the center line c are θ1 = θ2 = 45 degrees.

The molded product 1 having a small width A and B of several tens of millimeters can be handled by the upper die 6 having the above-mentioned special shape, but the width A and B of each piece is approximately several hundred millimeters. In the case of a large molded product of this type, the upper mold 6 of this kind cannot cope with it, and as shown in FIG. 7, the inclination angles θ1 and θ2 of the pressing surfaces 9 and 10 at the tips are asymmetrical in the longitudinal direction (in the case of the illustrated example, θ1 > Θ
2) The upper die 11 and the lower die 12 having the V-shaped grooves 8 corresponding to the respective inclination angles θ1 and θ2 are used.

FIG. 8 shows a state in which the workpiece W is pressed between the upper die 11 and the lower die 12 described above. In the figure, F1 and F2 represent the pressure applied by the upper die 11,
This means the force that the plate material W to be processed receives from the lower die 12, and these forces F1 and F2 are the above-mentioned inclination angles θ1 and θ2.
, And their sizes and directions do not match. The resultant force F3 of these forces F1 and F2 is the horizontal component force F in the front-rear direction.
4, the horizontal component force F4 acts on the upper die 11.

Generally, the upper die of a press brake is
Since the structure is weak against the load in the front-rear direction, when a large horizontal component force F4 is applied, the upper mold and its mounting portion, ram, etc. may be damaged. There is also a method of increasing the thickness of the upper mold or ram in order to increase the load bearing capacity in the front-rear direction, but this method is not generally used because the bending shape of the plate material to be processed is limited.

As a method of solving this problem, a method of using the elastic body 13 instead of the lower mold as shown in FIGS. 9 and 10 is adopted. In the method shown in the figure, an elastic body 13 having a flat horizontal support surface 14 on its upper surface is held by a metal holding metal fitting 15, and a plate material W to be processed is placed on the horizontal support surface 14 of the elastic body 13. By pressing the processed plate material W by the mold 11 in which the inclination angles of the pressing surfaces 9 and 10 at the tips are asymmetrical in the front and rear, the processed plate material W is bent while the elastic body 13 is compressed and deformed.

In FIG. 10, F1 and F2 are upper molds 11.
It means the force that the plate material W receives from the elastic body 13 with respect to the pressing force by. The magnitude of these forces F1 and F2 is determined by the volume in which the elastic body 13 is compressed and displaced (hereinafter, “displacement volume”).
In FIG. 11, the deformation volume V1 by the front die surface 9 having a large inclination angle and the deformation volume V2 by the rear die surface 10 having a small inclination angle are shown by diagonal lines. According to the figure, since the front deformation volume V1 is larger than the rear deformation volume V2, the relationship between the forces F1 and F2 is F1> F2. Combined force F3 of these forces F1 and F2
Has a horizontal component force F4 in the front-rear direction, which is smaller than the method of FIGS. 7 and 8 in which the lower die 12 is used.

12 (1) to 12 (5) show a process in which the plate material W to be processed is bent. FIG. 12 (1) shows a state in which the upper die 11 is lowered and the tip of the upper die 11 contacts the plate material W to be processed placed on the horizontal support surface 14 of the elastic body 13. FIG. 12 (2) shows a state in which the upper die 11 is further lowered and the work sheet material W is slightly pushed in. The plate material W to be processed is bent by the pushing amount of the upper mold 11, and the elastic body 13 is slightly compressed and deformed. When the upper die 11 is further pushed in, the plate material W to be processed comes into surface contact with the front die surface 9 of the upper die 11, as shown in FIG. Up to this stage, the bending angle of the plate material W to be processed is the center line c
It is symmetrical with respect to. The plate material W is not in surface contact with the pressing surface 10 on the rear side of the upper mold 11. As the upper die 11 is further pushed in, the plate material W to be processed is gradually bent deeply as shown in FIG. 12 (4).
No surface contact with 0. By further pushing in the upper die 11, as shown in FIG. 12 (5), the plate material W to be processed comes into surface contact with the die surface 10 on the rear side of the upper die 11, and the plate material W to be processed is in the upper die. A bending shape along 11 is obtained, that is, a bending angle corresponding to the angle formed by the pressing surfaces 9 and 10 is obtained. At this point, the bending of the plate material W to be processed is completed and the upper die 11
When is increased, the bent portion of the plate material W to be processed is slightly expanded due to the springback phenomenon, but if the plate material W to be processed has the same thickness, a stable bending angle can always be obtained.

[0010]

However, the elastic body 1
In the above method using No. 3, the pressing surfaces 9, 1 of the upper mold 11 are
Only a bending angle corresponding to the angle formed by 0 can be obtained, and there is a problem that it cannot be processed to a bending angle shallower than the angle formed by the pressing surfaces 9 and 10 of the upper die 11. If the bending process is completed before the pressing surface 10 on the rear side of the upper die 11 comes into surface contact with the plate material W to be processed, that is, at the step shown in FIG.
Although an arbitrary bending angle shallower than the angle formed by the pressing surfaces 9 and 10 of the upper mold 11 can be obtained, the elastic body 13 is not completely homogeneous over the entire length, and moreover the degree of deformation at the side end portion and the central portion is large. Therefore, a constant bending angle cannot be obtained over the entire length, and it is difficult to perform highly accurate bending.

The present invention has been made in view of the above problems, and a plate material bending method capable of highly accurately processing a plate material to be processed into an arbitrary bending angle shallower than an angle formed by a pressing surface of an upper die, and a method thereof. The purpose is to provide a device.

[0012]

According to a first aspect of the present invention, the plate material to be processed is pressed and bent between the elastic body held by the holding metal fitting and the mold in which the inclination angle of the pressing surface at the tip is asymmetric in the front-rear direction. A method of bending a plate material, wherein the pressing force of the mold on the plate material to be processed is supported by a holding metal fitting on the side of the pressing surface with a steep inclination, and an elastic body is supported on the pressing surface side of the inclination angle. In this way, the work piece is bent.

According to a second aspect of the present invention, there is provided a plate material bending apparatus for pressurizing and bending a plate material to be processed between an elastic body held by a holding metal fitting and a die whose front end pressing surface has an asymmetric inclination angle back and forth. The holding metal has a support wall that supports the front surface and the rear surface of the elastic body, and among these support walls, the support wall on the side of the pressing surface with a steep inclination angle is the plate material of the elastic body. It is formed by projecting to the position of the support surface.

[0014]

[Function] The pressure applied by the mold to the plate material to be processed is supported by the holding metal fitting on the side of the pressing surface with a steep inclination angle, and by the elastic body on the pressing surface side with a gentle inclination angle. Since it is bent, the plate material to be processed can be processed with high accuracy at an arbitrary bending angle shallower than the angle formed by the pressing surface of the upper mold.

According to the bending apparatus of the second aspect, since the supporting wall on the side of the die surface where the inclination angle is steep is projected to the position of the supporting surface of the plate member of the elastic body, the metal for the plate member to be processed is projected. The pressure applied by the mold is supported by the holding metal fitting on the side of the pressing surface with a steep inclination, and by the elastic body on the side of the pressing surface with a gentle inclination.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the main parts of a press brake in which the bending method of the present invention is carried out. In this press brake, the table 20 and the ram 21 are vertically opposed to each other,
The elastic body 1 is attached to the upper surface of the table 20 via the holding metal fitting 22.
3 is attached and fixed. The upper die 11 is attached to the lower end of the ram 21 by a holder 23, and the ram 21 and the upper die 11 are integrally moved up and down by a drive source (not shown) such as a hydraulic cylinder. The upper mold 11 has a sharp tip, and the front and rear pressing surfaces 9 and 10 have asymmetrical inclination angles. That is, the front side pressing surface 9 is set to a gentle inclination angle, and the rear side pressing surface 10 is set to a steep inclination angle.

As shown in FIG. 2, the elastic body 13 is a columnar body formed of hard rubber or the like and having a rectangular cross-section, and four outer peripheral surfaces are turned up and down and front and back by a metal holding metal fitting 22. Thus, it is kept horizontal. The upper surface of the elastic body 13 serves as a flat horizontal support surface 14 for supporting the plate material W to be processed over its entire length.

The holding metal fitting 22 integrally includes a lower surface support wall 24 that supports the lower surface of the elastic body 13, a front surface support wall 25 that supports the front surface, and a rear surface support wall 26 that supports the rear surface. The elastic body 13 is retained in a fitted state in a retaining groove 27 having an upper opening surrounded by 24, 25 and 26. The upper end of the front support wall 25 is located at the center of the height of the elastic body 13, and the upper end of the rear support wall 26 is the front support wall 25.
Of the elastic body 13 from above the upper end of the horizontal support surface 1
Aligned to a height of 4.

As shown in FIG. 3, on the inner surfaces of the rear surface support wall 26 and the lower surface support wall 24, relief grooves 2 for escaping the bulged portions 13A and 13B of the elastic body 13 which are bulged due to pressure deformation.
8 and 29 are formed over the entire length. FIG. 4 shows another method for coping with such a pressure deformation of the elastic body 13. By forming a full length cutout 30 at the rear end edge of the horizontal support surface 14 of the elastic body 13. Generation of the bulging portion 13A is suppressed.

Next, a method of bending the plate material according to the above-described configuration example will be described. When the upper mold 11 is lowered integrally with the ram 21 by pedal operation, the tip of the upper mold 11 reaches the surface of the plate material W to be processed and comes into contact therewith. When the upper mold 11 is further lowered, the plate material W to be processed is bent by the pushing amount of the upper mold 11, but the pressure applied by the mold 11 to the plate material W to be processed at this time is a pressing surface with a steep inclination angle. On the 10 side, the upper end of the rear support wall 26 of the holding metal fitting 22 is supported, and on the stamping surface 9 side with a gentle inclination angle, the horizontal support surface 14 of the elastic body 13 is supported.

FIG. 3 shows a state in which the front die surface 9 has come into surface contact with the plate material W to be processed. Under such a state, the bending angle α on the front side of the bent portion of the plate material W to be processed is formed by surface contact with the pressing surface 9, and the bending angle β on the rear side of the bent portion is held with the tip of the upper die 11. It is formed by two-point contact with the upper end of the rear support wall 26 of the metal fitting 22, and a constant bending angle can be obtained over the entire length. In the stage shown in FIG. 3, since the rear die surface 10 and the plate material W to be processed are not in surface contact with each other yet, the die surface 9 of the upper die 11 is adjusted by adjusting the pushing amount of the upper die 11. The plate material W can be bent at an arbitrary bending angle shallower than the angle formed by.

In FIG. 3, F1 and F2 ″ are the forces that the plate material W to be processed receives from the elastic body 13, and F2 ′ is the plate material W to be processed.
Indicates the force received by the holding metal fitting 26, respectively.
The force F1 acts on the front side of the bent portion of the plate material W to be processed, and the resultant force F2 ', F2 "acts on the rear side of the bent portion.
A horizontal component force in the front-rear direction of the resultant force of these forces F1, F2 ', F2 "acts on the upper die 11, but this horizontal component force is smaller than that in the example using the lower die 12 shown in FIG. Will be things.

[0023]

As described above, according to the present invention, the pressing force of the mold on the plate material to be processed is supported by the upper end of the holding metal fitting on the side of the pressing surface having a steep inclination angle, and on the side of the pressing surface having a gentle inclination angle. Since the workpiece is bent while being supported by the horizontal support surface of the elastic body, the plate material to be processed can be processed with high accuracy at an arbitrary bending angle shallower than the angle formed by the pressing surface of the upper mold.

According to the second aspect of the present invention, since the supporting wall on the side of the die surface where the inclination angle is steep is projected to the position of the horizontal supporting surface of the elastic body, the pressure applied by the die to the plate material to be processed is steep. On the side of the die surface, which is supported by the upper end of the holding metal fitting,
In addition, there is an effect that the pressing surface having a gentle inclination angle can be supported by the horizontal support surface of the elastic body.

[Brief description of drawings]

FIG. 1 is a side view showing a main part of a press brake.

FIG. 2 is a side view showing an elastic body held by a holding metal fitting.

FIG. 3 is a side view showing a state in which a plate material to be processed is bent.

FIG. 4 is a side view showing another embodiment of the holding fitting and the elastic body.

FIG. 5 is a perspective view showing a U-shaped molded product.

FIG. 6 is a side view showing a state in which a plate material to be processed is bent into a U-shape.

FIG. 7 is a side view showing a state in which a plate material to be processed is bent into a U-shape.

FIG. 8 is an enlarged side view showing a pressed state of a plate material to be processed.

FIG. 9 is a side view showing a bending method using an elastic body.

FIG. 10 is a side view showing a bending state of a plate material to be processed.

FIG. 11 is an explanatory diagram showing a deformed volume of an elastic body.

FIG. 12 is an explanatory view showing a process of bending a plate material to be processed using an elastic body.

[Explanation of symbols]

 11 Upper mold 13 Elastic body 14 Horizontal support surface 22 Holding metal fitting 24 Lower surface support wall 25 Front surface support wall 26 Rear surface support wall

Claims (2)

[Claims] 1. A method of bending a plate material, comprising pressurizing and bending a plate material between an elastic body held by a holding metal member and a die having a front-end pressing surface having a front-back asymmetrical inclination angle. It is possible to bend the workpiece by supporting the pressing force of the mold against the work plate material with the holding metal fitting on the side of the pressing surface where the inclination angle is steep and the elastic body supporting the pressing surface side where the inclination angle is gentle. Characteristic plate bending method. 2. A plate material bending apparatus for pressurizing and bending a plate material to be processed between an elastic body held by a holding metal fitting and a die having a front-end pressing surface having a front-back asymmetrical inclination angle. The metal fitting has support walls for supporting the front surface and the rear surface of the elastic body. Among these support walls, the support wall on the side of the pressing surface having a steep inclination angle projects to the position of the support surface of the plate member of the elastic body. A bending device for plate materials.