JP2682119B2 - Hemming method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hemming method, and more particularly to simplifying the method.

2. Description of the Related Art A hemming process is performed on the edge of a plate-shaped work material that is a constituent member such as a hood and a door of an automobile body. For the hemming, for example, as described in JP-A-55-68133, (a) the main body of the material to be processed is restrained horizontally, and the end to be processed by the first preliminary curved blade is The first step of bending at a right angle to the horizontal plane to form the first preliminary bending portion, and (b) the first preliminary bending portion is further bent about 45 degrees by the second preliminary bending blade to form the second preliminary bending portion. It is usually carried out by three steps of two steps and (c) a third step of actually bending the second preliminary bending portion with a main bending blade.

However, in the above-mentioned hemming processing method, since the main bending is performed after the two preliminary bending steps, there is a problem that the number of steps increases and the processing is troublesome.

Further, there is a problem that the structure of the device for performing the above processing becomes complicated. Since the second spare curved blade bends the first spare curved portion extending at a right angle to the horizontal plane, that is, in the vertical direction by about 45 degrees, it moves in the direction intersecting the moving direction of the first preliminary curved blade and the main curved blade. Is essential. Since a normal press machine performs processing by moving the press ram vertically or horizontally, when adding a hemming function to the press machine, the moving directions of the first preliminary curving blade and the main curving blade are set to the press ram. It is necessary to provide a special motion conversion mechanism for converting the motion of the press ram into the motion of the second preliminary curved blade if the movement direction of the press ram is adjusted, which inevitably complicates the structure and increases the cost of the device. .

On the other hand, if a device dedicated to hemming as described in the above publication is provided separately from the pressing device, good hemming can be performed. However, the manufacturing cost of the device is high, and it is difficult to incorporate the hemming device into the press working line. Since the position of the hemming process in the press line is not constant, the hemming device usually has to be installed at a position off the press line. Therefore, there is a problem in that the required space is increased, and the conveyance route of the workpiece is complicated and the equipment cost is increased.

In view of the above problems, the present invention has a small number of steps, and
The object of the present invention is to obtain a hemming method capable of easily performing hemming with a normal press machine.

Means for Solving the Problems And, the gist of the present invention is to provide a hemming method,
(A) A work piece is curved by a first die that can approach and separate from each other, and the main body of the work material has a posture that is substantially orthogonal to the approaching and separating direction of the first die as a whole. The end to be hemmed is 45 in the approaching / separating direction.
It is constrained in a state of being inclined at an angle of about 10 degrees, and the first die and the preliminary curved blade are relatively moved in a direction parallel to the approaching / separating direction so that the end portion is made substantially parallel to the approaching / separating direction. By the first step of bending the front and back by 135 degrees until it becomes a preliminary bending part, and (b) the second mold that can approach and separate from each other, the work piece can be moved in the approaching and separating direction of the main body as a whole. The pre-curved portion is constrained to incline at an angle of about 45 degrees with respect to the approaching / separating direction of the second mold by being in a substantially right-angled posture and by eliminating the curvature of the main body portion. The second step is to perform a main bending of the preliminary bending portion by relatively moving the second die and the main bending blade in a direction parallel to the approaching / separating direction of the second die.

Effect In this hemming method, the hemming is completed by preliminarily bending the end portion of the workpiece in the first step and performing main bending in the second step. If the press machine is for forming by sandwiching the material to be processed from the vertical direction, the first die and the second die should be able to approach and separate in the vertical direction, and in the first step, The main body is constrained so that the end is inclined upward or downward at an angle of about 45 degrees with respect to the vertical direction, which is the approaching / separating direction of the first mold. However, in order to incline the end part by 45 degrees with respect to the vertical direction, rather than inclining the entire work material, the main body part as a whole is in a posture substantially perpendicular to the approaching / separating direction of the first die, that is, almost horizontal. However, the end portion to be hemmed is inclined by an angle of about 45 degrees with respect to the approaching / separating direction due to the bending of the main body. In this state, the first die and the preliminary bending blade are moved relative to each other, and the preliminary bending portion is formed by bending the end portion approximately 135 degrees back and forth until it becomes substantially parallel to the vertical direction. That is, the preliminary curved portion is directed downward when the end portion is previously inclined upward, and is upward when the end portion is inclined downward. Next, in the second step, the main body portion is restrained by the second mold in a state where the preliminary curved portion is inclined at an angle of about 45 degrees with respect to the vertical direction. However, even in this case, instead of inclining the entire work piece, the pre-curved portion approaches the second mold by almost eliminating the curvature in the first step while keeping the main body in a substantially horizontal posture.・ 45 in the separating direction
Be sure to incline at an angle of around 1 degree. In the stage of the first process, the preliminary bending part was bent back and forth 135 degrees using the bending of the main body part, so if the main body part is kept in a substantially horizontal posture and the bending is almost eliminated, the preliminary bending part will naturally move up and down. To 45
It will be tilted at an angle of around 1 degree. Then, the second die and the main bending blade are moved relative to each other up and down to perform the main bending of the preliminary bending portion, whereby the hemming process is completed.

In the present invention, about 45 degrees means the angle at which preliminary bending and main bending can be performed by moving the preliminary bending blade and the main bending blade in directions parallel to the approaching / separating directions of the first die and the second die, respectively. It depends on the index, the preliminary curved blade, the coefficient of friction between the main curved blade and the work material, the lubrication conditions, etc., but in general it can be implemented within the range of 45 ± 20 degrees, and 45 ± 15 degrees is possible. Desirable,
45 ± 10 degrees is especially desirable.

In addition, the first mold is a state in which the work piece is constrained by a curved portion formed by a set of parallel generatrixes such as partial cylindrical surfaces, and the body portion is curved in the first step, and the end portion is inclined about 45 degrees back and forth. When the restraint of the first mold is released, the main body returns to a flat plate shape by elastically, and if it does not return, it is forced by the second mold having a flat restraint surface. By extending the main body portion in a flat plate shape, the preliminary bending portion is tilted inward and backward by 45 degrees, and the main bending can be easily performed.

Even if the first-type constraining surface is not a curved surface, it is sufficient if the main body can be constrained in a state where the end is inclined, such as inclining the entire constraining surface. In the case of a press die that moves in the same direction, if the first die and the second die can be moved toward and away from each other in the left-right direction, hemming can be similarly performed.

As described above, in the present hemming method, hemming can be performed by moving both the preliminary curved blade and the main curved blade in parallel to the moving direction of the movable member of the press device such as the press ram, and the special motion is performed. It is not necessary to provide a conversion mechanism, the structure of the device is simple, and the cost can be reduced.

Moreover, since the hemming process can be performed in two steps of the preliminary bending and the main bending, it is possible to easily perform the process as compared with the conventional method.

Further, since hemming processing can be performed on the end portion of the material to be processed and pressing processing such as drawing processing and bending processing can be performed on the main body portion if necessary, the processing efficiency can be improved. .

In addition, in the first step, since the end portion is tilted about 45 degrees with respect to the approaching / separating direction of the first die due to the bending of the main body, the entire work material is almost in the approaching / separating direction of the first die. Can be held in orthogonal postures. Then, in the second step, by eliminating the curvature in the first step, the pre-bent portion is inclined at an angle of about 45 degrees with respect to the approaching / separating direction of the second die, so that the entire work piece is It can be maintained in a posture that is almost orthogonal to the approaching / separating direction of the two types.

Therefore, in both the first and second steps, the workpiece can be maintained in a posture substantially orthogonal to the approaching / separating direction of the mold, and both the first and second molds can be made compact. If the entire work material is tilted in the first step, the size of the entire first die in the approaching / separating direction increases, the cost of the first die increases, and the pressing device also needs to be large. Whereas according to the present invention, it is necessary to avoid the disadvantage.

Further, in the case where the entire work material is tilted in the first step, it is often necessary to carry in and carry out the work material with respect to the first die in the tilt direction. In that case,
While the apparatus for conveying the workpiece is complicated and the equipment cost is high, the inconvenience can be avoided according to the present invention.

The above two disadvantages increase as the size of the work piece increases, so that the effect of the present invention can be more effectively enjoyed as the size of the work piece increases.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 is an inner panel of an automobile body which is a work material. The inner panel 10 is manufactured from a steel plate, and the main body 12 is pressed while the end portions are
14 is hemmed as shown in (f) of the figure,
The end portion 14 is bent 180 degrees toward the main body portion 12 side.

The hemming process of this inner panel 10 is
(A), (b) and (c) the first die 16 and the preliminary curved blade 18 and (d), (e) and (f) the second die 20 and the main curved blade 22. These are attached to a press device (not shown), and are relatively movable in the same direction as the press ram, that is, in the vertical direction, using the press ram as a drive source. The first die 16 includes an upper die 24 and a lower die 26 having a constraining surface forming a partially cylindrical surface that is gently curved upward.
The auxiliary curved blade 18 is disposed adjacent to the lower mold 26. The auxiliary curved blade 18 is immovable relative to the bolster of the pressing device, and a cushion device is provided between the lower die 26 and the bolster. The upper die 24 is moved down by the press ram, abuts against the lower die 26 and pushes it down against the elastic force of the cushion device, so that relative movement in the vertical direction between the lower die 26 and the auxiliary curved blade 18 is performed. Give rise to.
On the other hand, the second mold 20 is an upper mold 28 having a horizontal and flat restraining surface.
And the lower die 30, the main curved blade 22 is disposed adjacent to the upper die 28. The lower die 30 is supported immovably by a bolster, and the upper die 28 and the main bending blade 22 are moved up and down by a press ram, but a cushion device is provided between the upper die 28 and the press ram.

 The hemming method will be described below.

In this embodiment, the hemming processing of the end portion 14 and the main body portion
The pressing process of 12 is performed in parallel, but since the pressing process is performed in the same manner as the conventional method, detailed description thereof will be omitted.

First, in a state where the upper mold 24 and the lower mold 26 of the first mold 16 are separated from each other, as shown in (a), the main body 12 of the inner panel 10 is placed on the lower mold 26, and the end 14 is first It is placed in a state of protruding from the mold 16 to the side of the auxiliary curved blade 18 side. At this time, the lower mold 26 is held in the lifting device by the cushion device, and is at a position higher than the preliminary curved blade 18. Next, as shown in (b), the upper mold 24
Is lowered to restrain the main body 12. As a result,
12 bends along the constraining surface, and the main body 12 is kept substantially horizontal as a whole, while the end 14 is inclined downward at an angle of about 45 degrees with respect to the horizontal direction. If the upper mold 24 is further lowered from that state, the lower mold 26 is lowered against the elastic force of the cushion device, and the preliminary curved blade 18 is relatively raised,
As shown in (c), the end portion 14 is bent upward by about 135 degrees to form a preliminary bending portion 32. The preliminary curved portion 32 is bent in parallel with the vertical direction, that is, perpendicular to the horizontal plane. The above is the first step.

Next, the pre-bent inner panel 10 is supported by the lower die 30 of the second die 20 shown in (d). Due to the springback of the main body portion 12, the preliminary bending portion 32 is inclined slightly inward from the vertical. Then, as shown in (e), the upper die 28 and the main curved blade 22 are lowered by a press ram, and the upper die 28 and the lower die are
The main body 12 is constrained between 30 and 30. Since the preliminary bending portion 32 is bent about 135 degrees with respect to the main body portion 12 in the first step, the warp of the main body portion 12 is extended by the pressing of the upper die 28 to correct the curvature, and the main body portion 12 is When restrained horizontally, the preliminary bending portion 32 is inclined inward at an angle of about 45 degrees with respect to the vertical direction. If the press ram is further lowered in this state, the main mold blade 22 is lowered while the upper die 28 is stationary due to the cushioning action of the cushion device, and the preliminary bending portion 32 is pressed from above to perform the main bending. The preliminary bending portion 32 is bent 180 degrees toward the main body portion 12 as shown in (f),
This completes the hemming descent. The above is the second step.

As is clear from the above description, when the preliminary bending portion 32 is bent, the tip of the preliminary bending portion 32 needs to slide on the main bending blade 22, so that the preliminary bending portion 32 moves vertically. The larger the angle θ ₂ (see FIG. 3) formed with respect to each other, the easier the main bending. On the other hand, even when the end portion 14 is pre-bent, slippage occurs between the tip of the end portion 14 and the preliminary curved blade 18, and the end portion 14
The greater the angle θ ₁ (see FIG. 2) formed with respect to the vertical direction, the easier pre-bending. Then, the angle theta ₁ which the end portion 14 during pre-bending makes with the vertical direction, it is not independent of the angle theta ₂ which makes with the pre-bent portion 32 during the bending vertically, by increasing the theta ₁ theta ₂ is inevitably small. Therefore, in order to easily perform both the preliminary bending and the main bending, it is desirable that both θ ₁ and θ ₂ be 45 degrees.

However, this is because the friction coefficient between the end portion 14 and the spare curved blade 18 is equal to the friction coefficient between the spare curved portion 32 and the main curved blade 22,
In addition, when it is assumed that other conditions such as the bendability of the end portion 14 and the preliminary bending portion 32 are also equal, and when these are different, the end portion 14 and the preliminary bending portion 32 are respectively in the vertical direction. It is better to make the formed angles θ ₁ and θ ₂ different from each other.

Further, due to the convenience of the inner panel 10 itself, or the first die 16 and its peripheral members, the end portion 14 is vertically
In some cases, it may not be possible to incline at 45 degrees, and similarly, due to the circumstances of the second mold 20 and its peripheral members, the preliminary curved portion 32 may be inclined in the vertical direction.
It may not be tilted 45 degrees. In such a case, how much the angle formed by the end portion 14 and the preliminary bending portion 32 with respect to the vertical direction can be reduced (the angle at this time is referred to as a limit angle) depends on the end portion 14 and the preliminary bending portion. It changes depending on the magnitude of the frictional force between the blade 18 and between the preliminary bending portion 32 and the main bending blade 22. The critical angle can be reduced by improving the lubrication conditions between them, increasing the hardness of the preliminary curved blade 18 and the main curved blade 22, and reducing the surface roughness. Generally, if the angle formed by the end portion 14 and the preliminary curved portion 32 with respect to the vertical direction is in the range of 45 ± 20 degrees, the present invention can be implemented, and it is desirable that it is 45 ± 15 degrees. 45 ± 10 degrees is especially desirable.

In the present embodiment, in the second step, the main bending blade 22 was configured to approach the lower mold 30 of the second mold 20 to perform the main bending, but with a different mold from the main bending blade 22. The main bending may be performed by.

Further, in the case where the press machine performs processing by sandwiching the material to be processed from the left and right direction, it is assumed that the first die, the second die, the preliminary curved blade, the main curved blade, etc. are relatively moved in the left and right direction. It suffices, and hemming processing can be satisfactorily performed even in this way.

In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a hemming process which is an embodiment of the present invention. FIG. 2 is an explanatory view showing the inclination angle of the end portion of the workpiece, and FIG. 3 is an explanatory view showing the inclination angle of the preliminary curved portion. 10: Inner panel, 12: Body part 14: End part, 16: First mold 18: Preliminary curved blade, 20: Second mold 22: Main curved blade, 32: Preliminary curved portion

Claims (1)

(57) [Claims] 1. A first mold capable of approaching and separating from each other,
The work piece is curved so that the main body of the work piece is in a posture that is generally at a right angle to the approaching / separating direction of the first die, while the end to be hemmed is in the approaching / separating direction. It is constrained in a state of being inclined at an angle of about 45 degrees, and the first die and the preliminary curved blade are relatively moved in a direction parallel to the approaching / separating direction so that the end portion is substantially parallel to the approaching / separating direction. By the first step of bending back and forth by 135 degrees until it becomes a preliminary bending part, and the second mold that can approach and separate from each other, the work piece is almost entirely moved in the approaching and separating direction of the second mold. The pre-curved portion is constrained to incline at an angle of about 45 degrees with respect to the approaching / separating direction of the second die by being in a right angle posture and by substantially eliminating the curvature of the main body portion, The second die and the curved blade are parallel to the approaching / separating direction of the second die Hemming working method, which comprises a second step of the bending preliminary bending portion by relatively moving in a direction.