JPH10192995A - Bending method for core and hollow material for bending - Google Patents

Abstract

(57) [Abstract] [Purpose] In push-through bending of a hollow section having an irregular cross-section, it performs high-precision and high-productivity bending by preventing cross-sectional deformation and wrinkles. [Structure] In a bending process in which a hollow profile 3 is pushed through a fixed mold 1 and a movable mold 2, a core 20 is arranged at a position where a load in the hollow profile tends to concentrate and cross-sectional deformation easily occurs, and supported by a mandrel. Process while doing. The cross section deformation is prevented by supporting the inner surface of the profile in a region where the mandrel does not act due to the flexibility and elasticity of the core. The productivity can be improved by fixing the core to the mandrel as an appropriate length and integrating it with the mandrel. By arranging the spacing block between the two cores, the operation of the core can be improved and its operation length can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for bending hollow members having various cross-sectional shapes used for structural members such as frame members of vehicles such as automobiles and architectural members. In particular, the present invention relates to a bending process suitable for a thin-walled cross-section or a hollow cross-section having a cross-sectional shape in which a part of the cross-section is easily deformed by bending.

[0002]

2. Description of the Related Art In bending of a hollow profile, a tensile force and a compressive force act on the outside and inside of the cross section of the profile, respectively, so that the cross-sectional shape is flattened and deformed, and wrinkles and seats are deformed. In many cases, the cross section cannot be maintained due to bending. In particular, when the cross-sectional shape of the hollow material is not symmetrical such as circular or square, this tendency is remarkable in the case of an irregular cross-section, etc., and the bending process is performed uniformly and maintaining the cross-sectional shape. It was difficult to do. In order to prevent such deformation of the cross-sectional shape, use a thick-walled one, increase the thickness of a part of the cross-section, or reduce the occurrence of such cross-sectional deformation or wrinkles on a part of the cross-section. A method of providing a rib or the like for prevention has been adopted. However, increasing the wall thickness to reinforce it leads to an increase in weight, which is contrary to the demand for reducing the weight of products and parts. Is not preferable because it complicates the structure and lowers productivity, and increases the cost.

Further, in order to solve such a problem, it has heretofore been performed that a hollow material is filled with sand or pellet-like granular material to perform bending. According to this method, when the hollow profile is bent, sand and the like filled in the hollow profile are uniformly bent from the inside to the cross-section and the entire bent region, and the deformation is prevented. for,
It is effective for thin hollow sections and hollow sections with irregular cross sections.However, productivity is low due to the need for cleaning work such as sand filling and removal after bending. there were. In addition, a mandrel is arranged inside the hollow profile and supported from the inside to prevent deformation of the cross section. According to this method, since bending can be performed in a state where the mandrel is inserted and arranged from one end of the hollow profile, productivity is good, but the entire cross section is uniformly supported for the irregular cross section due to the structure of the mandrel. It is difficult to bend the hollow section having an irregular cross section, as will be described later in detail with reference to FIGS. . In order to support the inner surface of the hollow material and prevent cross-sectional deformation in the area where a large load is applied during bending, the mandrel is made of a flexible material, or an elongated member is bundled to make the entire mandrel flexible. Attempts have been made to extend the distance between the fixed mold and the movable mold, which are subject to large loads, by adding a characteristic, but the structure of the mandrel is complicated, the cost is increased, and processing of various types of material is performed. There were drawbacks that could not be addressed.

FIG. 1 shows these conventional push-through bending. In FIG. 1, a movable mold 2 that can move up and down toward the fixed mold 1, moves in the depth direction and the near side in the figure, and is rotatable is arranged, and the shape member 3 is moved from the fixed mold to a predetermined position and angle. In this manner, the movable mold set in the above is pushed in the direction of arrow A to perform a bending process with a curvature determined by the positional relationship and angle of these molds.
In this case, the movable mold by bending F _1, a large load that F ₂ acts on the vicinity of the fixed mold outlet. Naturally, these reaction forces act on the profile. The deforming action of the cross-sectional shape due to the reaction force is particularly remarkable when the cross-sectional shape of the profile is not axially symmetric and has an irregular cross-section, as shown in FIG.
Taking an example of a cross-sectional shape in which one side of a rectangular cross section is narrowed narrowly, in FIG. 2, when bending in the Y direction of the strong axis direction with respect to the X direction and the Y direction of the cross section of the material, F ₁ , F ₂ Becomes large. On the other hand, when the thickness of the profile is thin, or when a part of the cross section has an easily deformable portion (arrow A in the drawing), the cross section is deformed by the loads of F ₁ and F ₂ . 2 is deformed by F ₁ as shown in FIG. 2 (b). Further, modified as shown in FIG. 2 (d) by bending the case of direction, the load of F ₂ in FIG. 2 (c),
In addition, wrinkles occur.

In order to prevent such deformation, as shown in FIG. 1, a mandrel 10 is placed in a hollow profile 3 by a mandrel rod 11 and molding is performed. The range in which the mandrel operates is shown in the figure. As described above, the inner surface of the hollow section cannot be supported in the entire region where the hollow section is subjected to bending deformation only to such an extent that the hollow section partially protrudes from the fixed mold.
Therefore, in the case of performing a deformed cross-sectional shape member or a bending process having a small radius, it is inevitable that the cross-sectional shape is deformed between the fixed die and the movable die.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem. In press-through bending, a region where a large load is applied by a fixed die and a movable die is formed. It is an object of the present invention to obtain a good bent shape material by supporting from the inside of the material, suppressing such cross-sectional deformation and wrinkles, and improving the productivity.

[0007]

SUMMARY OF THE INVENTION In order to achieve the object, the present invention provides a press-through bending method using a fixed mold and a movable mold, wherein a cross section of the hollow section is easily deformed in the hollow section. A pre-arranged auxiliary core that maintains a predetermined cross-sectional shape along the point of, is a method of bending a hollow material in which a mandrel and a core supported by the mandrel support the inner surface of the shaped material and bend, The hollow core is bent by placing the attached core in both or one of the regions where the load by the movable mold and the fixed die is concentrated, and then bending the hollow core by fixing the attached core to the mandrel. This is a method for performing processing. A bending mandrel in which a supporting core having a cross-sectional shape along the cross section of a required portion of the hollow shape member is fixed to a mandrel, and a bending is performed by disposing a spacing holding block between the plurality of supporting cores. It is a mandrel for processing.

[0008]

According to the first aspect of the present invention, since the mandrel is relatively rigid, the mandrel is relatively rigid in the bending region between the fixed die and the movable die, or in a portion where the load is concentrated by these dies. While it is difficult to support from the inside of the hollow profile, these auxiliary cores have a cross-sectional shape corresponding to the predetermined section of the cross-section of the hollow profile, so that it can also handle complex cross-sectional shapes In addition, since the diameter is a part of the cross section, the diameter is smaller than that of the mandrel, and the material can be appropriately selected, so that flexibility can be provided. For this reason, the hollow profile is supported by the mandrel and supported from the inner surface in close contact with the portion where the load of the hollow profile concentrates, and is extended to a range beyond the action of the mandrel, thereby deforming the hollow profile. It is to prevent. In addition, the invention according to claim 2 arranges these auxiliary cores corresponding to a region where a load is concentrated at the time of bending between the fixed die and the movable die, so that the inner core comes into close contact with the inner surface of the hollow profile. By supporting the extended portions supported by the mandrel, the deformation of the hollow profile is effectively prevented.

According to the third and fourth aspects of the present invention, the attached core is protruded from the tip of the mandrel and is fixed to be integrated with the mandrel. This makes it possible to perform bending efficiently without prior arrangement. Further, according to the fifth aspect of the present invention, by disposing a holding block for keeping a constant interval between the plurality of attached cores, the shape of the supporting cross section is maintained even when these cores are extended. This enables more accurate bending.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example will be described below with reference to the drawings. FIG. 3 shows a bending process corresponding to FIG. 1, in which an auxiliary core 20 is arranged along a part of the cross-sectional shape of the hollow profile 3 along the axial direction of the hollow profile. FIG. 4 (a)
(C) shows the cross-sectional shape of the hollow profile and the arrangement of the auxiliary cores arranged according to the direction of bending. The example of the auxiliary core shown in FIG. 3 corresponds to the bending process of FIG. 4A, and has a cross-sectional shape corresponding to the tapered cross-sectional shape portion of the hollow profile, and has a hollow profile in advance. It is arranged inside along the axial direction in a state of being in close contact with the inner surface. In bending 3, the mandrel 10 prevents the cross deformation of the profile and supported from the inside against a load F ₁ which receives from the load F ₂ and the movable mold receiving the subscript core from the fixed mold. The attached core 20 is arranged along the profile and has flexibility, so that it is bent by the bending of the profile and exerts a pressing force on the inner surface of the profile due to its elasticity. To maintain the cross-sectional shape. As described above, the supporting core is supported by the mandrel to prevent the cross-sectional deformation of the profile, and furthermore, due to its elasticity, exerts its supporting force in a region where a large load acts beyond the mandrel, thereby causing the cross-sectional deformation of the profile. Can be prevented. The attached core is disposed in advance in the hollow profile before bending, and moves together with the hollow profile during the process shown in FIG.

The effect of preventing deformation by the attached core is the same as that of the conventional method of filling sand, because the attached core is in close contact with the inner surface of the profile, so that it acts uniformly on a predetermined area of the inner surface of the profile. In addition, it is possible to effectively prevent the cross-sectional deformation of a hollow material having a thin wall or an irregular cross section. The flexibility and elasticity of the attached core may be appropriately adjusted by appropriately selecting the material such as a metal material or hard plastics, or changing the cross-sectional area thereof. The example illustrated in FIG. 4B is an example in which the position of the tapered cross section of the profile is reversed from the above example. The example (c) is a case where the bending direction is alternately bent in the opposite direction, and the core is disposed on each side in the bending direction. The bending state is shown in FIG. In FIG. 5, due to the elasticity of the attached core, the function of the attached core on the inner side of the bending process (upward in FIG. 5) is reduced on the rear side during bending, but the effect is reduced. Is enough. FIG. 7 shows a modified mandrel of FIG. 5 in which the mandrel is a swinging core type. The inner auxiliary core is held at a predetermined position over the entire processing area, and the operation and effect of the auxiliary core are reduced. It is fully demonstrated. Also in this case, the mandrel may have a shape excluding the attached core portion, so that the mandrel does not need to be a complicated deformed shape. In the above example, the attached core is previously arranged in the hollow profile, but in this case, the installation work and the removal work after bending are required.

Therefore, by fixing these cores to the mandrel, the work involved in these processes can be omitted, and the efficiency of bending can be improved. An example is shown in FIG. In the figure, the attachment cores 20 are arranged on both sides of the mandrel 10, but extend from the mandrel to constitute a cross-sectional deformation restricting portion of the hollow profile. In this case, the length of these additional cores is only required to be able to support the profile in a region where a large load is applied, where bending between the fixed die and the movable die is performed. Further, as another embodiment, FIG.
As shown in (a) and (b), the space holding block 25 can be disposed between the two attached cores with the elastic connecting member 26 interposed therebetween. By doing this,
The hollow profile can be supported from the inside to the inside and outside on both sides of the bending arc, and since this supporting force is held by the two attached cores via the spacing block, the hollow section is separated from the mandrel. It is also effective in a bending area where a large load acts. Therefore, it is possible to maintain the cross-sectional deformation preventing action over the entire bending processing region and perform more accurate bending. FIG. 9 shows a state in which bending is performed using the auxiliary core shown in FIG.

[0013]

As described above, according to the present invention, it is easy to cause cross-sectional deformation of a thin hollow member or a hollow member having an irregular cross-section, and the cross-sectional deformation of a difficult-to-bend shape member is easily performed. Can be performed with high accuracy and high efficiency.

[Brief description of the drawings]

Fig. 1 Example of conventional push-through bending

FIG. 2 shows a relationship between a bending direction of a hollow profile and its easily deformable portion A: an example where the easily deformable portion is on the opposite side of the bending direction (a) and its modified example (b), and where the easily deformable portion is on the bending direction side. Example (c) and its modification (d)

FIG. 3 shows an example in which the attached core of the present invention is applied.

FIG. 4 shows an example of the cross-sectional shape of the shaped material and the arrangement of the cores: an example in which the attached core is arranged on the side opposite to the bending direction (a), an example in which the attached core is arranged on the bending direction side (b), Example of alternate bending in opposite direction (c)

FIG. 5 is a bending example of FIG. 4 (c).

FIG. 6: An example in which an attached core is fixed to a mandrel

FIG. 7 is a modification of FIG. 5;

FIG. 8 shows an example (a) in which a spacing block is arranged between two attached cores, and a cross section (b) thereof.

FIG. 9 shows an example of bending using the attached core of FIG. 8;

[Explanation of symbols]

1: fixed mold 2: movable mold 3: hollow section 1
0: Mandrel 11: Mandrel rod 20:
Attached core 21: Swing core 25: Spacing holding block 26: Connecting material 28: Block groove A: Easily deformable part

Continuing from the front page (72) Inventor Harumichi Hino 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Inside the Nippon Light Metal Co., Ltd. Group Technology Center (72) Inventor Keiichi Sugiyama 2-2-2 Higashi Shinagawa, Shinagawa-ku, Tokyo No. Japan Light Metal Co., Ltd.

Claims (5)

[Claims] In a push-through bending method using a fixed mold and a movable mold, a flexibility for maintaining a predetermined cross-sectional shape along a section of a cross section where deformation of the profile is likely to occur in the hollow profile. A method for bending a hollow material, comprising: disposing an attached core having in advance, and bending the supporting member by supporting a mandrel and the core supported by the mandrel on the inner surface of the profile. 2. A press-through bending method using a fixed mold and a movable mold, wherein an auxiliary core that maintains a predetermined cross-sectional shape is provided in at least one of regions where loads are concentrated by the movable mold and the fixed mold. A method for bending a hollow material, comprising disposing and bending an inner surface of a profiled material by a mandrel and the core supported by the mandrel. 3. The method of bending a hollow material according to claim 1, wherein the attached core projects from a tip of the mandrel and is fixed. 4. A bending mandrel characterized in that a flexible core having a cross-sectional shape along a cross section of a required portion of a hollow profile is fixed to a tip of the mandrel. 5. The mandrel for bending a hollow material according to claim 4, wherein a spacing block is provided between the plurality of attached cores.