JPH0215291B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to small radius bending (2DR or less) of Al-Mg aluminum alloy tubes, and particularly to suppressing thinning etc. during bending plastic working process. The present invention relates to a method and device for suppressing thickness loss suitable for.

[Background of the invention]

Small radius bending (2DR or less) is generally performed on piping, but in this case, there are no specific regulations regarding the wall thickness reduction rate, and thick-walled pipes are used to reduce the wall thickness due to bending. I was getting used to it. Al―
As for Mg-based aluminum alloy tubes, their elongation in terms of mechanical properties is low, so it is at the limit to carry out bending with a small radius, and there is no bender bending that has a means for suppressing thickness loss. In addition, related devices of this type include, for example,
There are issues such as No. 14966.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for suppressing wall thinning that occurs on the back side of a tube due to plastic deformation during bending in small radius bending of a tube to be processed.

[Summary of the invention]

The basics of bender bending of piping is pull bending.
Compression bending, side bending, etc. are used for special materials and special processing bending.

The present invention combines the above-mentioned three bending processes and controls the bending load and bending speed to process Al-Mg aluminum, which is difficult to bend, using a processing method similar to general bender bending. This allows small-R bending of alloy pipes and the like to be carried out with a reduction in thickness of 20% or less.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In the figure, reference numeral 1 denotes an aluminum tube as a workpiece, one end of which is fastened and fixed by a bending clamp 3 to a draw-bending die 2 that performs the draw-bending process.
The draw-bending die 2 is connected to a tensioning cylinder 7 via a bending-die pulling chain 10 . A compression mold 4 is provided in contact with the other end of the aluminum tube 1 to perform compression bending, and is connected to a compression cylinder 8. Reference numeral 5 denotes a side die for performing side bending, which is provided in pressure contact with the side surface of the aluminum tube 1, facing the draw-bending die 2, and is connected to a side cylinder 9.

In the above-described configuration, the draw-bending die 2 and the compression die 4 are operated to perform the draw-bending process and the compression-bending process, and at the same time, the side die 5 is operated to perform the side-bending process. In this case, the compression bending load by the compression die 4 is made to be about 10% overload and about 5% overspeed compared to the pull bending load by the pull bending die 2, and the side bending speed by the side die 5 is set to be about 5% overload, and the side bending speed by the side die 5 is made to be more than the compression bending speed. By setting the overspeed to about 10%, thinning of the aluminum pipe 1 due to bending can be suppressed.

Figure 3 shows the basics of plastic deformation during bending of the aluminum pipe 1 and the principle of suppressing thinning according to the present invention. The neutral axis during bending shifts from the geometrical axis to the ventral side, and the back side is stretched and thinned while being processed, with the ventral side tending to increase in thickness through compression and the back side tending to thin out through tension. In the present invention, by providing a side die 5 and operating it at an overspeed than the compression die 4, the neutral axis is shifted from the geometric axis to the back side, as shown in FIG. 3B, and thinning on the back side is prevented. It was designed to suppress it. Although this embodiment has been described using an aluminum tube (Al--Mg aluminum alloy tube) as the workpiece, the present invention is not limited to this. That is, it can be applied not only to materials that are difficult to bend, such as special pipes such as titanium and stainless steel pipes, but also to various types of pipes.

〔Effect of the invention〕

According to the present invention, it is possible to perform small radius bending of a pipe having poor bendability while suppressing thinning due to plastic deformation on the back side.

[Brief explanation of drawings]

Fig. 1 shows a small R of a pipe to be processed showing an embodiment of the present invention.
FIG. 2 is a sectional plan view of the bending thinning suppressing device, FIG. 2 is a sectional view along A-A in FIG. 1, and FIGS. DESCRIPTION OF SYMBOLS 1...Aluminum tube, 2...Draw bending type, 3...Bending clamp, 4...Compression type, 5...Side type, 7...Tension cylinder, 8...Compression cylinder, 9...Side cylinder, 10...Bending type tension chain.

Claims (1)

[Claims] 1. Adding compression bending to the draw bending of the pipe to be processed with a load greater than that of the draw bending, and adding side bending at a faster speed than the compression bending by pressing the side surface of the tube, A method for suppressing wall thinning when bending a pipe with a small radius, the method comprising controlling the load and speed of each bending process within a certain range. 2. A stretching and bending device that fixes one end of the tube to be processed and applies a tensile load to perform the bending process, and a compression bending device that performs compression bending by controlling and applying a compressive load to the other end of the tube to be processed. 1. A side bending device that faces the drawing and bending device and presses the side surface of the tube to be processed to control the bending speed to perform side bending.