JPH0381019A - Pipe bending device - Google Patents

Abstract

PURPOSE:To enable bending of high accuracy by moving a pipe synchronously with the rotation of a clamp and bending die, and pressure controlling a pressure die with which the pipe is made to closely stick to the bending die in the direc tion where compressive force is given to the outer peripheral part of pipe bend ing. CONSTITUTION:The bending die 2, the clamp 3 with which a material (pipe) 1 to be worked is held on the bending die 2 and the pressure die 4 which is moved synchronously with the revolution of the bending die 2 are provided. The pipe 1 is made to closely stick to the bending die 2 with the pressure die 4. The pressure die 4 is made to be pressurizingly controllable with a hydraulic cylinder 5 and an electromagnetic proportional reducing valve 6 in the direction that the outer peripheral part of pipe 1 bending is given with compressive force. By this way, the thickness reduction of thin pipe can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pipe bending device, and particularly to a bending structure used when bending a thin-walled pipe to a small radius.

[Conventional technology]

For example, steel or aluminum pipes are often used as compensation piping for air conditioners.

Recently, small R
Piping bending is becoming more common for bending (bending R of 02 times the diameter or less). When such a small radius bend is performed, there is a large loss of O thickness at the outer periphery of the pipe bending area, and this was countered by increasing the thickness of the O pipe material.
As a means for suppressing thinning, Jikai No. 61-222684 Fukubushi proposes a method in which a tidal bending force is applied by a pressure mold at overspeed to the compression bending process.

[Problem to be solved by the invention]

However, in the above-mentioned prior art, the pressure die is moved at an overspeed, so when the bending radius changes, it is necessary to change the four-stroke speed of the pressure die in order to keep the amount of overspeed constant.

In addition, since the pressure mold is moved at overspeed and a side bending force is applied to the side surface of the pipe due to the dynamic friction force between the pipe surface and the pressure mold, the pipe is in a trro state, and the pipe P and the pressure mold M are in a trro state.

Due to oil adhesion, etc., the force applied to the side surface of the pipe may vary widely, and the effect of suppressing wall thinning also varies greatly.

Therefore, the present invention aims to solve these problems. Furthermore, when applying compressive force to a pipe using a pressure type, D-shifting occurs at the inner periphery of the bending pipe due to excessive compressive force, and D-shift O occurs at the bending start point. It is also a purpose to prevent this, since it causes deterioration of the flattened surface ``4''.

[Means to solve the problem]

In order to achieve the above purpose, instead of applying an axial compressive force to the pipe by moving the pressure die at an overspeed than the pipe during bending, the pipe and pressure die are moved simultaneously without slipping, and the pressure die is moved at an overspeed than the pipe. This applies a compressive force in the axial direction to the pipe. In addition, by freely changing the axial compressive force applied to the pipe during bending, it suppresses wall thinning at the outer periphery of the bend, and prevents pipe D-shifting and flattening that occur due to compressive force. .

[Effect]

When bending a pipe, the pipe is held between a bending die and a clamp, and the pipe is bent tightly against the bending die by a pressure die (by rotating the bending die, the pipe is deformed along the bending die). , the bending process is performed, but tensile stress is generated on the outer periphery of the pie 10, and compressive stress is generated on the inner periphery, resulting in thinning at the outer periphery and increase in thickness at the inner periphery.At this time, the pressure mold is By applying compressive force in the axial direction to the bent portion of the pipe using a pressure mold while the pipe is in close contact with the pipe, the neutral axis of bending D moves toward the outer circumference of the pipe, thereby suppressing wall thinning.

As long as the pressure mold does not slip against the pipe,
By applying compressive force in the axial direction to the pipe, a stable wall thinning prevention effect can be obtained. Furthermore, by adding means for increasing the coefficient of friction with the pipe to the pressure type, it becomes possible to increase the compressive force in the axial direction that can be applied to the pipe. moreover,
Instead of applying a constant O compressive force from the beginning of bending to the end of the pipe bending, the compressive force is increased in areas where there is a large bending angle due to wall thinning, and the compressive force is increased at the beginning of bending and the inner circumference of the bend where pipe O buckling is likely to occur. By reducing the compression force at the end of bending, where wrinkles are likely to occur, there is less wall loss and high precision bending becomes possible.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 8.

First, FIG. 1 is a configuration diagram of a pipe bending apparatus O according to an embodiment of the present invention.

As shown in Fig. 1, 2 is a bending die for bending the vibrator l to be processed, 8 is a clamp for fixing the Loe pipe l to be cut to the bending die, and 4 is a bending die for bending the pipe l to be processed. 5 is a hydraulic cylinder that applies compressive force in the annular direction to the pipe, and U is an electromagnetic proportional pressure reducing valve for electrically controlling the pressure of oil O supplied to the hydraulic cylinder. With the above configuration, the linear to-be-processed vibrator is held by the two pumps 8 and the bending die 2, and the to-be-processed vibrator is bent by rotating the bending m2 in the direction of the solid line arrow in the figure. At this time, the pressure mold 4 is moved by the hydraulic cylinder 5.
By applying pressure in the axial direction of the vibrator to be processed, it is possible to suppress thinning at the outer circumferential portion of the bent breaking vibrator and to improve the aspect ratio.

Furthermore, if a constant axial compressive force is applied to the vibrator to be processed during bending, the aspect ratio may deteriorate at the beginning of bending, and creases may occur at the inner periphery of bending at the end of bending. Therefore, by changing the pressure applied by the hydraulic cylinder 5 using the electromagnetic proportional pressure reducing valve 6 according to the type and bending angle of the vibrator to be processed, it is possible to further improve the aspect ratio and prevent the occurrence of creases. .

Figures 8 and 4 show the D thickness reduction "4" and the flattening ratio when applying D axial compressive force to the processed vibrator using a pressure mold (dashed line) and when processing without applying it (solid line), respectively. .

FIG. 2 shows another embodiment, and is a block diagram in which a ball screw 7 and a motor 8 are used as a method of applying an axial compressive force to the caroe pipe.

In this case, more detailed control is possible compared to hydraulic pressure.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a pipe bending device that can suppress thin-walled pipe O thinning and perform highly accurate bending with a small aspect ratio.

[Brief explanation of drawings]

FIG. 1 shows a pipe bending bag yto according to an embodiment of the present invention.
Figure 2 is a configuration diagram of another embodiment of the present invention O pipe bending apparatus iO, Figure 8 is an explanatory diagram of dimensional specifications of thinning rate and flattening ratio, and Figure 4 is a diagram showing another embodiment of the present invention. It is a comparative diagram of the thinning rate θ and the flattening rate of processed products when bending is performed by the conventional method and the case where the bending process is applied. 1... Vibrator to be processed 2... Bending m 8...
Flang 4...Pressure machine 5--Hydraulic cylinder
6... Solenoid proportional pressure reducing valve 7... Ball screw 8... Motor. P ding@欿〃0 7hfyyukito(:ha が り ふ゛ axial direction 1 shim f!, Kaede Kainaka?) し. Ah< 11iJ R4fu'Mla 7'tt,'S nofugufforceQ.

Claims (1)

[Claims] 1. A bending mold that serves as a mold for bending, a clamp that grips the pipe as a workpiece to the bending mold, and a pressure that moves in synchronization with the rotation of the bending mold to bring the pipe into close contact with the bending mold. 1. A pipe bending device comprising a pipe rotary drawing and bending device, characterized in that the pressure mold is provided with means capable of controlling pressure in a direction that applies compressive force to the outer circumference of the pipe when bending the pipe. 2. In the pipe bending device according to claim 1, means capable of changing the pressure applied by the pressure die in the direction of applying compressive force to the outer periphery of the pipe bent according to the rotation angle of the bending die and the type of pipe. A pipe bending device characterized by being provided with. 3. The pipe bending device according to claim 2, further comprising means for increasing the coefficient of friction at the portion in contact with the pressure type pipe.