JPH06238386A - Bending type - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the yield of bent products. Constitutions are provided on at least one of the bending surfaces 4, 5 of the movable die 3 and the fixed die 2 of the bending die, and uneven portions 6, 7 for limiting relative slip between the workpiece 1 and the die. Form. As a result, even if the shape of the workpiece 1 is not uniform, the fixed die 2 or the movable die 3 or both of the machining surfaces 4,
Bending can be performed while limiting slippage between the workpiece 5 and the workpiece 1. Therefore, even if the shape of the workpiece 1 is not uniform, there is no local thin-walled portion,
Moreover, the bending process suitable for the shape of the product can be surely performed, and the yield of the product can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending mold which is improved so as to improve the yield of bent products.

[0002]

2. Description of the Related Art A part (product) such as a front upper arm having a complicated shape is processed through the following several steps. An example of this is shown in FIG. 13. First, in step (a), the material is cut into a predetermined size and then heated, and in step (b), the material is rolled into a rough shape, and this roll processing is performed. Next, the material is bent into a shape suitable for the shape of the part in the step (c), and the semi-processed material is then hot forged to form the rough land (d) and finish (e) steps. , Coining (f) step, deburring (g) step, and then SB cleaning, inspection and painting are completed to complete one product.

The present invention corresponds to the bending step (c) in the above steps, and in this bending step, for example, when the wall thickness is changed to form a thin portion, the next forging step is performed. When this bent semi-finished product is forged, cracks may occur in its thin portion. Then, as a result of the inspection, such a product becomes a defective product, so that the bending process affects the yield of the product. Also, since there is a forging process and a pressing process after the bending process, when the bent product is carried into the next process, the posture of the bent product may be constant, especially in an automatic processing line. Required.

As shown in FIG. 11, a conventional general bending die is composed of a fixed die 2 and a movable die 3 having smooth working surfaces 4 and 5 formed in conformity with the shape of the product. The workpiece 1 was positioned so as to be bridged over the fixed die 2 (b), and the movable die 3 pushed a predetermined portion of the workpiece 1 to bend it (c).

As another conventional bending die of this type, for example, Japanese Patent Publication No. 31538/1993 discloses a product in which a plurality of products having the same shape are pressed at a time by a single press die. In order to make the wall thickness uniform, preforming is performed as a pre-process. That is, when products of the same shape are pressed by one press die at a time, the meat portion of the raw material moves during the pressing process, and thus a product having a uniform thickness cannot be obtained for a plurality of products. Therefore, preforming is performed so that the thickness of each product is uniform, and the meat is distributed.

[0006] Specifically, an uneven portion corresponding to the number and shape of products is formed on the pressing surfaces of the fixed mold and the movable mold for preforming, and the height of the uneven portion at the center of the uneven portions is set. By changing the height of the unevenness so as to make it higher and lower the height of the unevenness other than that, the meat of the material pressed in the area where the height of the unevenness is high has a low height of the unevenness. It moves to the side to distribute the meat of the material.

[0007]

Among the conventional bending molds, the bending mold having the smooth bending surface shown in FIG. 11 has the following problems. As shown in FIG. 12 as an example, the front upper arm 1 has an end portion (A).
(E) and central part (C) are thick, and their middle parts (B) and (D)
When the work piece having a non-uniform shape such as a thin work piece is bent by the fixed die 2 and the movable die 3 having a smooth bending surface as shown in FIG. Since the rigidity of each part of the object is different, in order to balance the force between the pushing force of the movable die 3 in the direction of the arrow X and the reaction force received by the fixed die 2 and the rigidity of the workpiece, the workpiece is processed. The processing surface 4 of the fixed die 2 is on the (front upper arm 1).
A sliding force is generated between the movable surface 3 and the processing surface 5 of the movable die 3 in the arrow Y direction (axial direction of the workpiece).

For example, when slippage occurs between the movable die 3 and the processed surface 5, the position of the pressing force of the movable die 3 acting on the thick portion (C) of the front upper arm 1 is deviated. If the central part of the thick part (C) is pushed and the thin parts (B) and (D) are drawn into the machining surface 4 of the fixed mold 2 under the same conditions, the point of action of the force of the movable mold 3 (B When it is shifted to the () side, the amount of pull-in on the (B) side becomes large, and there is a problem that the (B) part is stretched during the bending process and a thin part is locally generated.

Even if the central portion of the thick portion (C) is pushed by the movable die 3, the thick portion (C) and the thin portion (B) (D)
Depending on the shape of the workpiece, such as the diameter ratio and the length ratio between the and, the thick part (C) and the thin part (B) during bending
It may be bent so that it may be bent at the step between (D) and the part where the bending stress concentrates.
In the workpiece 1 bent by (3), a dent as shown by 103 is formed by bending. In this state, when hot forging is performed in the step of rough land (d), the recess 103 progresses to the workpiece 1 and causes a crack in the product.

When the forging process is performed in the state where the thin portion and the dent portion are formed as described above, a crack is generated in the portion to reduce the yield of the product, and the product is thick so as to conform to the shape of the product. Even if the roll is bent into a narrow portion and a narrow portion, if the bending is inappropriate for the roll processing as described above, the posture of the work piece will vary and automatic conveyance to the next forging process will occur. However, there is a problem in that it is difficult to carry out the automatic transfer and sometimes the automatic transfer cannot be performed, resulting in a decrease in productivity.

The press die disclosed in Japanese Examined Patent Publication No. 31538/1993 is one in which the meat of the material is positively moved in preforming, and a plurality of products are formed by one die at a time. Suitable to do. However, in the case of one-piece molding such as the front upper arm 1 as shown in FIG. 12, there are the following problems.

That is, when bending is performed based on the technical idea of positively moving the meat of the material,
As shown in 11, when the front upper arm 1 is set so as to be stretched over the bending surface 4 of the fixed die 2, and when the bending surface 5 of the movable die 3 is pushed in the arrow X direction, the meat of the front upper arm 1 is indicated by the arrow. It will move in the Y direction.
When the front upper arm 1 is bent in the direction of the arrow Y and bent as shown in FIG. 11, the semi-finished product 101 bent as shown in FIG. Thin parts may occur. This semi-finished product 1
When 01 is forged in the next step, the forging step, as shown in FIG. 10, there is a problem that a crack is generated in the B part of the product 102 and the product yield is reduced.

The present invention provides a bending die that solves the above problems by eliminating slippage and local bending between the bending die and the material.

[0014]

Means for Solving the Problems According to the present invention for solving the above problems, a bending die formed on a fixed die is mounted on a fixed die by pushing a movable die having a shape corresponding thereto. In the bending die for bending the material, the uneven portion for limiting relative slip between the material and the die is formed on a part of the bending surface of at least one of the movable die and the fixed die. It is a feature.

[0015]

Since the present invention is constructed in this way, it has the following actions. That is, since the uneven portion that limits the relative slip between the material and the die is formed on a part of the bending surface of at least one of the movable die and the fixed die of the bending die, the shape of the workpiece is not uniform. Even in this case, it becomes possible to perform bending while limiting the slippage between the work surface of the fixed type or the movable type or both of them and the work piece.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1 and 2 are plan views of the movable mold 3 and the fixed mold 2 shown in correspondence with the movable mold 3 and the fixed mold 2 in FIG. 11, for example. FIG. 1 shows the movable mold and FIG. 2 shows the fixed mold. . In FIG. 1, a concave-convex surface 6 is formed at the tip of the processing surface 5 of the movable die 3, which is the portion that the workpiece first contacts during bending, while the fixed die 2 is bent as shown in FIG. Occasionally, the uneven surface 7 is formed on the shoulder portion of the processing surface 4 of the fixed mold 2, which is the portion where the workpiece first comes into contact, and at the portion where bending stress concentrates on the workpiece when the workpiece is bent. A convex portion 401 is formed on the processed surface 4 at a corresponding position. The height of the convex portion 401 is the height at which the workpiece abuts on the workpiece before it is bent during the bending process.

As shown in FIGS. 3 and 4, the shapes of the uneven surfaces 6 and 7 are such that the tips are sharp. Further, in this embodiment, the pitch P and height H of the uneven shape of the uneven surface 6 formed on the movable die 3 are the pitch P and the height H of the uneven shape of the uneven surface 7 formed on the shoulder portion of the fixed die 2. Is bigger than The pitch P and the height H of this uneven shape differ depending on the shape and size of the rolled work, but for the front upper arm, the pitch P is 5 mm and the height H is 2.5 mm. And 7 have the same specifications.

Some products may not have indentations on the uneven surface 6 or 7 at the time of bending, or some indentations may be allowed. If the indentations are not allowed, the pitch P and Height H is small and
Do not sharpen the shape too much, and conversely increase the pitch P and the height H when allowed, and
The shape may be sharpened to improve the sliding effect. Further, as shown in FIG. 4, the uneven surface 7 formed on the shoulder portion of the fixed mold 2 is a mounting portion 701 (actually, in the machined surface, on which the workpiece is mounted at the beginning of bending in this embodiment). Is formed in the corner portion 702 from the (not present) to the processed surface 4.

The operation of this embodiment having the above-mentioned structure will be described below. The work piece is pre-rolled so as to conform to the shape of the product like the front upper arm 1 shown in FIG. 7, and therefore its rigidity is greater than the bending force of the movable die 3 and the fixed die 2. It is uneven. Therefore, first, the case where the uneven surface 6 is formed only on the movable die 3 and the uneven surface 7 is not formed on the fixed die 2 will be described.

As shown in FIG. 7, the workpiece (front upper arm 1) is placed on the fixed die 2 and the movable die 3 is moved in the direction of the arrow X to apply a bending force to the workpiece. Three
In order to maintain the balance between the pushing force of the fixed die 2, the reaction force of the fixed die 2 and the rigidity of the work piece, a force in the direction of the arrow Y is generated on the work piece and the work piece tries to slip. Since the slippage is limited by the uneven surface 6 formed on the upper surface, the pushing force of the movable die 3, the reaction force of the fixed die 2, the rigidity of the work piece and the force of which the slippage is limited by the uneven surface 6 are limited. Thus, the forces are balanced with each other, which makes it possible to bend the work piece while limiting the slippage.

Next, the case where the concave and convex surface 7 is formed only on the fixed mold 2 and the concave and convex surface 6 is not formed on the movable mold 3 will be described.
Also in this case, as shown in FIG. 7, when the workpiece (front upper arm 1) is placed on the fixed die 2, the movable die 3 is moved in the direction of the arrow X and a bending force is applied to the workpiece, the movable die is moved. In order to maintain the balance between the pushing force of 3, the reaction force of the fixed die 2 and the rigidity of the work piece, a force in the direction of the arrow Y is generated on the work piece and the work piece tries to slip. Since the slippage is limited by the concave-convex surface 7 formed on the surface 2, the pushing force of the movable die 3, the reaction force of the fixed die 2, the rigidity of the workpiece, and the force by which the slippage is limited by the concave-convex surface 7. The forces are balanced between each other, which makes it possible to bend the workpiece while limiting the slippage.

When the uneven surfaces 6 and 7 are formed on the fixed die 2 and the movable die 3, respectively, the force balance is such that the force that restricts the workpiece from trying to slide in the arrow Y direction is the uneven surface. Movable mold 3 as given by 6 and 7
The pushing force of the fixed die 2, the reaction force of the fixed die 2, the rigidity of the work piece, and the force of which slippage is limited by the uneven surfaces 6 and 7 are balanced with each other, whereby the work piece Bending can be performed while limiting slippage. In this case, the force of the work piece trying to slide in the direction of the arrow Y is limited by both the concavo-convex surfaces 6 and 7, so that the force is dispersed to the concavo-convex surfaces 6 and 7, and the specifications of the concavo-convex surface without indentation are obtained. It becomes possible to do.

In this way, the slip between the movable die 3 and the work piece, the fixed die 2 and the work piece or between the movable die 3 and the fixed die 2 and the work piece is limited to bend as shown in FIG. When processed, since the convex portion 401 corresponding to the portion where the bending stress of the workpiece is concentrated is formed on the processing surface 4 of the fixed die 2, the bending is performed in the process of bending the workpiece. The convex part 401 first hits the part where stress is concentrated and is easily bent,
The molding pressure of this portion becomes high, and the bending at this portion is restrained, whereby the machining surface 5 of the movable die 3 comes into close contact with the workpiece, and the machining surface 5 of the movable die 3 is transferred to the workpiece. Therefore, it becomes possible to perform highly accurate bending.

Then, the convex portion 401 makes an indentation on the workpiece, but since the convex portion 401 is formed on the processing surface 4 of the fixed die 2, the indentation 105 is a semi-finished product 101 as shown in FIG. Can be done outside of. As a result, when this semi-finished product 101 is hot forged, as shown in FIG. 10, this indentation 105 is pushed out to the outer edge of the burr 106, and there is no effect on the product.

FIG. 5 shows the mold in the above bending step.
5 is a schematic view of FIG. 5 viewed from the side, and after the workpiece (front upper arm 1) is set on the fixed die 2 at a predetermined position while being placed on the lifter 8 in the step (a). The movable die 3 is moved forward to bend it, then the movable die 3 is retracted in the step (b), and the workpiece whose bending is completed in the step (c) is lifted by the lifter 8 to perform the next machining. Transfer to the process.

In this bending step, especially in the automatic processing line, the posture of the workpiece 1 placed on the lifter 8 for which the bending processing is completed must be constant. Therefore, since the bending process is performed while limiting the slippage of the work piece, the shape of the bent work piece is constant, and the work piece bent into this constant shape is scooped up by the lifter 8 as it is. Therefore, the posture of the workpiece on the lifter 8 can be made constant.

[0027]

As described above in detail, according to the present invention, unevenness for limiting relative slip between the material and the mold is formed on a part of the bending surface of at least one of the movable mold and the fixed mold of the bending mold. Since the part is formed, even if the shape of the work piece is uneven, bending can be performed while limiting the slippage between the work surface of the fixed type and / or the movable type and the work piece. .

As a result, even if the shape of the work piece is not uniform, there is no local thin-walled portion, and the bending work suitable for the shape of the product can be surely performed. It is possible to improve the retention and surely perform bending processing that matches the shape of the product, so that the posture of the workpiece picked up by the gripper becomes constant, for example, automatically in the next processing step. In addition, it can be reliably transported.

[Brief description of drawings]

FIG. 1 is a plan view of a movable die that is an embodiment of the present invention.

FIG. 2 is a plan view of a fixed die which is an embodiment of the present invention.

3 is a partially enlarged view of the uneven surface in FIG.

4 is a partially enlarged view of the uneven surface in FIG.

FIG. 5 is a plan view showing a bending step.

FIG. 6 is a schematic view of FIG. 5 viewed from the left side surface.

FIG. 7 is a plan view showing the relationship between a bending die and a workpiece before bending.

FIG. 8 is a plan view showing a bent state.

FIG. 9 is a plan view of a work piece that has been bent.

FIG. 10 is a plan view of a forged product.

FIG. 11 is a view showing a state where a bending process is performed using a conventional bending die.

FIG. 12 is a diagram showing bending of a work piece using a conventional bending die.

FIG. 13 is an explanatory diagram showing a product processing step.

[Explanation of sign]

 1 Front upper arm (workpiece) 2 Fixed type 3 Movable type 4 Machining surface 401 Convex part 5 Machining surface 6 Uneven surface 7 Uneven surface

Claims (1)

[Claims] 1. A bending mold for bending a material placed on the fixed mold by pressing a movable mold having a shape corresponding to the bending surface formed on the fixed mold, wherein the movable mold is a movable mold. Also, a bending die is characterized in that an uneven portion for limiting relative slip between the material and the die is formed on a part of at least one bending surface of the fixed die.