JP2001353530A - Method and apparatus for bending small radius of tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus to suppress thinning of a back face side in a simple constitution in the case of bending a metal tube having a low mechanical elongation in a small radius. SOLUTION: By controlling start timing of side bending for pull-bending and its working speed, the neutral axis of a bending section is moved at 5-10% toward a back face side than the geometrical axis, while metal thinning of the back face side is suppressed, small radius bending of the tube is conducted. A side bending apparatus to a pull-bending apparatus generally used in tube bending are combined, by controlling a pull-bending speed and a side bending speed, small radius bending of a tube having a low mechanical elongation is achieved in a thinning rate of <=20%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to small R bending of pipes, and more particularly to a method and apparatus for small R bending of pipes suitable for suppressing wall thinning during bending plastic working.

[0002]

2. Description of the Related Art As described in Japanese Patent Publication No. 2-15291, a conventional apparatus performs a compression bending process and a side bending process in a pull bending process to bend a tube in accordance with a small R bending process of the tube. The thickness of the back of the part was reduced.

[0003]

In the above prior art, the thickness reduction is suppressed by performing compression bending and side bending at the time of pull bending. However, this prior art does not specifically disclose the timing at the start of the compression bending or side bending processing operation or the load of the compression bending or side bending processing. In addition, since each bending process is operated by the hydraulic control means, when the compression bending is too early than the pulling bending due to operation delay, etc.
There was a risk that the work tube would buckle.

[0004] An object of the present invention is to use a combination of a pull bending process and a side bending process without using a compression bending process that causes buckling of a tube, and to form a bent portion along with a small radius bending process of a pipe to be processed. It is an object of the present invention to provide a method and an apparatus for small-R bending of a pipe capable of suppressing wall thinning occurring on the back side of a pipe.

[0005]

In the above prior art, the respective speeds in the case of performing the bending process by combining the pull bending, the compression bending, and the side bending are set to 1: 1.05: 1.15 as a guide. ing. That is, the side bending speed is controlled at about 15% overspeed with respect to the pulling bending speed.

[0006] On the other hand, in the small R bending process of the pipe of the present invention, when performing the process by combining the pull bending and the side bending,
By accelerating the start of the side bending process with respect to the pull bending process, the neutral axis of the bent portion of the pipe to be processed can be shifted to the back side of the bent portion compared to the case of simply bending. it can. In the present invention, it is important to set individual speeds and timings for the interlocking of the pull bending and the side bending. The processing conditions that can suppress the wall loss of the pipe during processing were set.

In the method for small-R bending of a pipe according to the present invention, the side bending of the pipe to be processed is started at a timing earlier than that of the bending, and before the side bending die slips on the pipe to be processed. Start the processing operation of the pull bending process, and set the processing speed of the side bending process to 15 to
It is characterized by being made 20% faster.

Further, the apparatus for bending a small R pipe according to the present invention comprises: a drawing means for pressing a drawing die against a drawing bending part of a pipe to be processed; A side bending unit which is installed by pressing a side mold to a processing part to perform side bending, and a processing operation of a pulling bending unit is started earlier than the side bending unit, so that the bending operation of the bending part of the pipe to be processed is started from the geometrical axis. Interlocking means for moving the vertical shaft by 5 to 10%.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to FIG. In FIGS. 1 and 2, reference numeral 1 denotes an aluminum pipe as a workpiece, one end of which is fastened and fixed by a clamp 3 to a pulling die 2 for performing a pulling process. The pull-bending mold 2 is connected to a tension cylinder 5 via a bending-type tension chain 7. Reference numeral 4 denotes a side bending die for pressing the bending die 2 and pressing the side surface of the aluminum pipe 1 to perform side bending, and is connected to the side cylinder 6. A control device is provided for interlocking a tension cylinder 5 for driving the pulling die 2 and a side cylinder 6 for driving the side bending die 4 at the timing described below. In addition, as the control device, an operation detector that detects an operation start situation and an operation stroke of the tension cylinder 5 and the side cylinder 6 or an output detector that detects an output of the tension cylinder 5 and the side cylinder 6 by hydraulic pressure is provided. Each is installed. Based on these detection results,
A microcomputer is used to control the starting start timing of the tension cylinder 5 and the side cylinder 6 and the respective load outputs. This control means is interlock control means.

In the above-described configuration, the pull-bending process and the side-bending process are performed in conjunction with each other so that the pull-bending process and the side-bending process are performed with a predetermined time lag. Specifically, first, only the side bending is started, and the pull bending is started before the side bending die 4 slides on the surface of the workpiece 1. Further, by setting the side bending speed of the side bending die 4 to be 25% faster than that of the pull bending die 2, the aluminum pipe 1 shown in FIG.
Of the neutral axis 8 at the back of the geometric axis 9
By shifting by 10%, the thickness reduction on the back side of the aluminum pipe 1 can be suppressed.

By combining the side bending process and the pull bending process in this manner, it is possible to suppress the thinning occurring on the back side of the bent portion of the aluminum pipe 1 and to reduce the structure of the bending device by the conventional compression bending process. , Can be simplified as compared with a combination of side bending and pull bending. Further, in the conventional bending apparatus, it is necessary to control each processing tool so that compression bending, side bending, and pull bending are simultaneously performed, and a high-precision apparatus and advanced control technology are required. Was. On the other hand, in the present embodiment, two processing means of side bending and pulling bending are controlled, and the control system can be simplified as compared with the conventional one. In addition, the side bending process and the pull bending process are performed in advance of the side bending process, and control the interlocking of the two control systems. It can be simplified. Further, in the present embodiment, since the compression bending is not performed, it is possible to prevent buckling that is likely to occur in the workpiece due to the compression bending. by the way,
In the bending according to this embodiment, by combining the side bending apparatus with the drawing bending apparatus and controlling the drawing bending speed and the side bending speed, the small R bending of the pipe having a small mechanical elongation is reduced. It can be achieved within 20%.

Although this embodiment has been described with reference to an aluminum tube,
The present invention is not limited to this. That is, it can be applied to various kinds of pipes, not to mention materials which are difficult to bend.

[0013]

As described above, according to the present invention, the plasticity of the rear side of the bent portion can be reduced by combining the two types of the small R bending process of the tube having poor bending processability, namely, the pull bending and the side bending. Processing can be performed with high precision while suppressing wall thinning due to deformation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view of a small R bending apparatus for a pipe showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory diagram of a neutral axis and a geometric axis in a bending section of a pipe.

[Explanation of symbols]

1: Aluminum pipe, 2: Bending type, 3: Bending clamp, 4
... side bending type, 5 ... tension cylinder, 6 ... side cylinder, 7 ... bending type tension chain, 8 ... neutral axis, 9 ... geometric axis.

Claims (2)

[Claims] 1. A side bending process of a pipe to be processed is started at a timing earlier than a pull bending process, and a processing operation of a pull bending process is started before a side bending die slides on the pipe to be processed. A small R bending method for a pipe, characterized in that the processing speed of the side bending process is made 15 to 20% faster than the processing speed of the pull bending process. 2. A pulling and bending means for pressing a drawing die to a drawing and bending portion of a pipe to be processed to perform drawing and bending; The bending operation of the side bending means for performing the bending process and the pulling bending means is started earlier than the side bending means so that the neutral axis is 5 to 10% of the geometric axis of the bent portion of the pipe to be processed.
A small radius bending apparatus for a pipe, comprising: interlocking means for moving.