JPH04339522A - Diameter shrinkage-working method for end part in metallic pipe - Google Patents

Abstract

PURPOSE:To easily enable the working of a shrunk diameter part at end part of a metallic pipe. CONSTITUTION:Waving work is executed to over the whole periphery of the end part in the metallic pipe 1 with wave rolls 2. Successively, crest parts 4a in the wave 4 are crushed with flat rolls. By this method, the shrunk diameter part is smoothly formed without unreasonable deformation.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for reducing the diameter of the end of a metal pipe, such as a downspout or a downspout joint, which is used to thin the end of a metal pipe to form a connection, etc. be.

0002

2. Description of the Related Art When forming a connection part at the end of a metal pipe such as a downspout, it is sometimes necessary to reduce the diameter of the metal pipe. However, although plastic working can easily increase the diameter of the end of a metal pipe, the current situation is that it is not possible to reduce the diameter of the end of the metal pipe.

0003

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for reducing the diameter of the end of a metal pipe by easily reducing the diameter of the end of the metal pipe. To provide a diameter reduction processing method.

0004

[Means for Solving the Problems] In order to achieve the above object, the method of reducing the diameter of the end of a metal pipe according to the present invention involves corrugating the end of a metal pipe 1 over the entire circumference with a wave roll 2. Then, the crests 4a of the waves 4 are crushed by a flat roll 3.

[0005]

[Operation] The end of the metal pipe 1 is corrugated and squeezed, and the crest 4a is flattened to form a reduced diameter portion 5 having a small diameter. Thereby, the reduced diameter portion 5 can be formed without causing excessive deformation during plastic working.

[0006]

[Embodiment] The present invention processes the end of a metal pipe 1 made of metal such as stainless steel or copper as shown in FIG. 6(a), and processes a reduced diameter portion 5 as shown in FIG. 6(b). It is something to do. This processing consists of a first molding process as shown in FIG. 1, a second molding process as shown in FIG. 2, and a third trimming process as shown in FIG. In the first forming process, corrugation is performed using a pair of wave rolls 2. As shown in FIG. 1(a), the outer and inner surfaces of the end of the metal pipe 1 are pressed and sandwiched between a pair of wave rolls 2 having a plurality of alternating peaks and troughs, and the pair of wave rolls 2 are reversely rotated. The metal pipe 1 is rotated in the direction shown in FIG. At this time, the trough portion 4b of the wave 4 becomes a narrowing portion, and the peak portion 4a becomes a narrowing absorption portion that absorbs deformation caused by narrowing. In the second forming process, the outer and inner surfaces of the waves 4 are pressed and sandwiched between a pair of flat rolls 3 having stepped portions as shown in FIG. 2(a), and the pair of flat rolls 3 are driven to rotate in the opposite direction. to flatten the peaks 4a. As a result, the peak portion 4a is crushed to form a substantially smooth reduced diameter portion 5 as shown in FIG. 2(b). In the third trimming process, as shown in FIG. 3(a), a core roll 7 is inserted into the reduced diameter part 5, a round piece 8 is pressed against the outer surface of the reduced diameter part 5, and the round piece 8 covers the entire circumference. It is cut across, and a chamfered portion 9 is formed at the end as shown in FIGS. 3(b) and 4. In this way, a reduced diameter portion 5 as shown in FIG. 5 is formed, and has some irregularities 10 on its outer surface. The reduced diameter part 5 formed in this way
is used as a connection part, and the end of another metal pipe 1 is fitted and connected. At this time, if there are some unevenness 10,
It has a retaining effect, an adhesive retention effect, and an effect of cutting off capillary action.

[0007]

[Effects of the Invention] As described above, in the present invention, the end of a metal pipe is corrugated all around with a wave roll, and then the crests of the waves are crushed with a flat roll. It absorbs the deformation caused by drawing and can be made flat by crushing the ridges, and can be smoothly processed to reduce the diameter and form the reduced diameter part, and the reduced diameter part has some unevenness. When it remains as a connection part, it has a retaining effect, an adhesive reservoir effect, an effect of cutting off capillary phenomenon, etc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first molding step of an embodiment of the present invention, in which (a) is a cross-sectional view of the molded state, and (b) is a half-sectional view showing the state after molding.

FIG. 2 is a diagram showing the second molding process same as above, (a
) is a sectional view of the molded state, and (b) is a half sectional view showing the state after molding.

FIG. 3 is a diagram showing a third trimming step same as the above, in which (a) is a half-sectional view during trimming, and (b) is a half-sectional view after trimming.

FIG. 4 is an enlarged cross-sectional view of important parts during trimming.

FIG. 5 is a front view showing the final product same as above.

FIG. 6 is a diagram illustrating an outline of the processing same as the above.

[Explanation of symbols]

1 Metal pipe 2 Wave roll 3. Flat roll 4 waves 4a Yamabe

Claims (1)

[Claims] 1. Diameter reduction processing of the end of a metal pipe, characterized in that the end of the metal pipe is corrugated over the entire circumference with a wave roll, and then the crests of the waves are crushed with a flat roll. Method.