JP3585275B2 - Bending equipment - Google Patents

Description

[Industrial applications]
The present invention relates to a method and apparatus for bending a hollow section.
[Prior art]
Generally, when bending a profile having a hollow cross section, wrinkles due to compression are likely to be generated inside the bend.
In particular, as an effective bending method for suppressing the generation of wrinkles, a tensile bending method in which a tensile force is applied in the axial direction to reduce a compressive stress generated inside the bending is widely adopted. However, the tensile side, which is the outer side of the bend, has a problem in that a predetermined bend shape cannot be obtained because the cross-sectional thickness is thin, the cross-sectional deformation is large, and constriction, cracks, etc. are easily generated, and the product shape is limited. was there.
[Problems to be solved by the present invention]
Since tension bending is formed by applying tension to both ends, the occurrence of wrinkles on the inner surface can be reduced to a considerably better level than other bending methods such as press bending, compression bending, etc. it can. However, tension is applied to the outer surface and a tensile stress is applied at the time of molding, so that there is a problem that cracks are easily generated on the outer surface.
Therefore, when bending is performed with reduced tension in order to eliminate cracks, if the tension is too low, internal wrinkles will be large and a predetermined product shape cannot be obtained. Therefore, in order to prevent the occurrence of wrinkles on the inner surface of the bend, it is necessary to secure the tension at a certain level or more. If the tension on the outer surface of the bend is not weaker than the tension on the inner surface, cracks are likely to occur on the outer surface. It became clear.
Accordingly, an object of the present invention is to provide a bending method and a device capable of obtaining a predetermined bending shape without generating wrinkles and cracks in an extruded profile having a hollow cross section.
[Means for Solving the Problems]
Means taken by the present invention to solve the above-described problem will be described below.
Inserting a core into each end of the profiled material having a hollow cross section, chucking the ends from inside and outside in the bending direction, applying tension, and pressing against the bending mold to bend and form. In the bending method, the chuck portion inside the bend is provided with an inner surface chuck die base 10 having a tapered portion and an inner surface chuck die 11 slidably disposed on the tapered portion, while the outer chuck portion is bent outside. The fixed plate 13 was attached to the chuck base mold 12 of the above, and a slide plate 14 of a substantially parallel plate was slidably provided on the fixed plate 13.
Here, the inner chuck portion and the outer chuck portion are connected by an arm 23, and a tensile force can be arbitrarily applied to the work by the stretch cylinder 17 via the stretch block 24. The stretch block 24 is slidable by a block guide 25. Further, the chuck portion was rotatable about a tension device unit turning shaft 18 as a center.
A forming method of applying a tensile force to a work and bending the work in the above-described configuration will be described below.
The work 2 is set on the die plate 6, and the center portion is fixed by the clamp device 7. The stretch cylinder 17 is retracted, and the chuck portions are positioned at the left and right sides of the work, respectively.
Next, the core mold is inserted into the hollow portion of the work by the core mold insertion and extraction cylinder 8. At this time, when the projection 19 provided on the core mold pushes the rear part of the inner surface chuck mold, the inner surface chuck mold 11 advances, the tapered portion slides, and the work is chucked with the slide plate 14. At this time, the deformation of the work is prevented by the core mold. Further, the chucking force of the work can be arbitrarily adjusted by a core-type insertion / extraction cylinder. Next, a tensile force acts on the work by advancing the stretch block 24 with the stretch cylinder 17, and also at this time, the chuck force is added because the inner surface chuck die is tapered, and slipping with the work is performed. Can be prevented.
Next, the press pressure cylinder 5 moves forward, the bending die 4 descends, and a force is applied to the work to bend the work. At this time, the chuck rotates around the tension device unit rotation shaft 18 and the work bending inner part. Is subjected to compressive stress, and tensile stress is applied to the outside of the bend. At this time, if a sliding force is applied between the slide plate and the fixed plate to a certain degree or more, the slide plate slides in a direction in which the tensile stress applied to the work is reduced. Therefore, cracking of the work outside the bending can be prevented. When the bending of the work is completed, the press pressure cylinder is retracted, the stretch cylinder is retracted, the work chuck is released, and the core die is pulled out.
At this time, the slide plate is returned to the original position by the slide plate return spring 15, and the inner surface chuck type is returned to the original position by the chuck type return spring 26.
This completes a series of bending steps.
[Action]
By having the work chuck mechanism of the present invention, the bending inner surface chuck type is slidably installed in a tapered shape as conventionally employed, so that a tensile force can be applied without the work slipping. On the other hand, a fixed tensile stress acts on the bending outer surface chuck portion due to a frictional force between the work slide plate and the fixed plate, but when a tensile stress is further applied, a slip occurs between the slide plate and the fixed plate.
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an example of a product formed according to the present invention.
A middle rib is provided with a width of 70 mm, a height of 100 mm, a thickness of 2 mm, and a thickness of 1.4 mm between the upper and lower surfaces, and has a bent shape of R = 300 mm on both ends and R = 230 mm on the inside. The wrinkle height of the bent portion on the inner surface is suppressed to 0.5 mm or less, and the outer surface is bent and formed without cracking.
In addition, it goes without saying that the hollow cross-sectional shape can be dealt with as needed by dividing the core type.
For example, a “□” cross section, a substantially trapezoidal cross section, and the like can be given.
FIG. 2 shows an overall view of a bending device according to the invention.
The bending die 4 is manufactured according to the bent shape of the product. In the case of the product example shown in FIG. 1, since the product is bent inside R = 230 mm, the springback amount after the bending is taken into consideration. And a bending die was manufactured at R = 220 mm.
The core mold 9 is made of nylon 6 made of material 6 so that it can be inserted into the hollow part in three parts in order to match the cross-sectional shape of the product. As long as the material used here can follow bending, there is no particular problem as long as it is generally used widely, and a resin material is generally good.
Further, the tensile force at the time of bending is preferably used while suppressing the generation of wrinkles on the inside of the bend and adjusting the range in which cracks are not generated on the outside of the bend. In the case of this example, 1100 to 1300 MPa was good. .
It is preferable to apply a lubricant or to provide an oil groove in order to maintain lubricity between the slide plate and the fixed plate in order to improve the slip. It is also possible to use an oil-impregnated material, for example, a casting in which oil is impregnated.
Under these conditions, when bending was performed in the order of the steps described above, a good product having no cracks on the outside of the bending and no wrinkles on the inside of the bending was obtained. At this time, the slide amount of the slide plate was about 20 mm.
【The invention's effect】
Since the slide plate of the chuck part that grips the outer side slides in the opposite direction to the tension direction and relaxes the elongation, the outer side does not crack due to tension, and the inner side has the effect of securing a bent shape with suppressed wrinkles. .
[Brief description of the drawings]
FIG. 1 shows an example of a product obtained according to an embodiment of the present invention.
FIG. 2 is an overall view of a bending device according to the present invention.
FIG. 3 shows a prior art chuck-type bending mechanism.
FIG. 4 shows a slide mechanism of a chuck section according to the present invention.
FIG. 5 is an overall view of a bending apparatus according to the present invention.
[Explanation of symbols]
1. Bend product 1a according to the present invention Bend outer surface 1b Bend inner surface 2 Work (coarse material for bending)
4 Bending mold 5 Pressing cylinder 6 Die plate 7 Clamping device 8 Core mold insertion and withdrawal cylinder 9 Core mold 10 Inner surface chuck base 11 Inner surface chuck 12 Outer surface chuck base 13 Fixed plate 14 Slide plate 15 ... Slide plate return spring 16 ... Tension device unit 17 ... Stretch cylinder 18 ... Tension device unit rotation shaft 19 ... ···· Die plate spring 22 ····· Outside surface crack 23 ···· Arm 24 ··· Stretch block 25 ···· Block guide 26 ···· Chuck type return spring

Claims (2)

In a forming device that performs bending by press forming while applying a tensile force to both ends of a profile having a hollow cross section, a core die is inserted into each of the bent portions from the left and right ends of the hollow profile, and the hollow is formed. The chuck portion on the inside of the bending of the chuck mechanism at both ends for applying tensile force to the profile has an inner surface chuck type base having a tapered portion and an inner surface chuck type slidably disposed on the tapered portion, A bending forming apparatus characterized in that a chucking portion on a bending outer side comprises a fixed plate disposed substantially parallel to a work side surface and a slide plate slidably disposed on the fixed plate. A bending method using the bending apparatus according to claim 1.

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