JPS6199525A - Bending method of pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention mainly relates to an improvement in a bending method that avoids deformation of the inner diameter of a metal pipe.

(Prior art) As shown in Fig. 2, the conventional method is to hold pipe A, which is a workpiece, horizontally with chunk B, and to use a deformation-preventing core bar held within vibrator A with fixing base C. Insert D and core D
Supply lubricating oil from oil tank F with pump E to the circle, and
Lubricating oil can be drawn out from a large number of oil injection holes G provided in the pipe to reduce the frictional resistance between the inner surface of the pipe and the surface of the core metal, for example.
Pipe A was bent by raising the bending tool to the upper pipe holder H1Jllll.

The reason why the frictional resistance is reduced by the lubricating oil is that the frictional resistance between the core metal and the pipe is large, and the part that is in contact with the core metal D outside the curved R (radius) part does not extend. A phenomenon occurs in which it does not shrink on the inside.

Therefore, only the part where the core bar D is not inserted expands and contracts, making it difficult to obtain good bending work, and in some cases, cracks may occur inside the pipe, so the entire pipe may shrink and contract. This is to do so.

(Problems to be Solved by the Invention) However, in the conventional method described above, it is an essential requirement to inject lubricating oil into the inside of the pipe. Therefore,
Because it is harmful to pipes used in the food industry, etc., the songs are made with f! It is necessary to clean it with I solvent etc.
It has the disadvantage of requiring an extra manufacturing process.

[Structure of the invention]

(Means for solving the problem) In the present invention, a deformation prevention core metal is inserted into the pipe, and the pipe is bent by applying an external force while applying ultrasonic vibration to the deformation prevention core metal. .

(Function) In the present invention, by applying longitudinal vibration in the axial direction of the pipe to the deformation prevention core inserted into the pipe, plastic processing called the Blaha effect can be achieved by ultrasonic plastic processing, etc. Reduce deformation resistance. If this plastic deformation resistance is made infertile, the frictional resistance will be reduced and the pipe will be bent in the desired direction.

For longitudinal vibration, use a frequency of 75 to /QQKH2, /K
If it is below Hz, it becomes noise pollution because it is an audible frequency /QQKH
If it is more than z, the converter in the vibrator section is small due to the wavelength and has the disadvantage that it is difficult to output power.

To explain the present invention in more detail based on FIG. 1, pipe A is held horizontally by chunk B as in the past,
Insert the deformation prevention core metal into the lid until it reaches the specified position. Then, an ultrasonic vibrator/ is fixed to one end of the core metal for preventing deformation,
Ultrasonic oscillator! The signal from the ultrasonic transducer/ is marked η
Then, apply longitudinal vibration to the deformation prevention core metal in the axial direction of the pipe A, and move the bending tool/towards the pipe holder H side using a pressurizing machine (
(not shown) to bend the pipe A.

(Example) Inner diameter / inside diameter 2S00 long copper pipe with outside diameter / 3
A 11g deformation prevention core was inserted and the bending was performed by applying pressure to the bending tool while applying ultrasonic longitudinal vibration to the deformation prevention core at a frequency of 2QKHz. As a result, it was possible to bend the pipe neatly ◇ [Effect of the invention] In the present invention, it is possible to bend the pipe neatly by reducing the frictional resistance between the core metal and the inner surface of the pipe without injecting lubricating oil. can. Therefore, there is no need for a cleaning step to remove the lubricating oil.

In addition, there is little wall thickness inside the pipe and it is uniform.

Also, less pressure is applied to the bending tool.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a device used in the pipe bending method of the present invention, and FIG. 2 is a partially cutaway front view of a conventional device. In addition, in the figure, A...Pipe, D...Core metal for preventing deformation, ■
is a bending tool, /... an ultrasonic vibrator, and 2... an ultrasonic oscillator.

Claims (1)

[Claims] A pipe bending method characterized by inserting a deformation-preventing core metal into the pipe and bending the pipe by applying an external force to the pipe while applying ultrasonic vibration to the deformation-preventing core metal.