JPS59183984A - Production of mitre bend - Google Patents

Abstract

PURPOSE:To prevent generation of an angle in a joint part and to prevent fluid loss of a mitre bend by curving and joining plural pipe bodies of which the joint parts incline relative with the pipe axis in such a way that the diameters of the elliptical end faces in the respective joint parts are approximate to a short diameter. CONSTITUTION:A straight pipe is alternately cut at an equal angle of inclination positive and negative to the pipe axis so as to have the equal shape of the end face, thereby manufacturing plural pipe bodies 1 each having an elliptical end face 2. Each body 1 is curved in such a way that the diameter in the long diameter part of the elliptical end face 2 thereof is approximate to the diameter in the short diameter part, thus forming a curved part 3. A notch 4 to serve as a groove for inside surface welding of the bodies 1 is provided and the joint parts 2 are welded from the inside of the pipe. A weld zone 5 is so formed as to have the wall thickness equal to the wall thickness of the bodies 1. The curved parts 3 are formed at both ends in the long diameter part of the faces 2 and it is also possible to form the same only in the long diameter part of the end faces on the curving outside of the bend.

Description

[Detailed description of the invention] The present invention relates to a miter bend method.

The conventional miter bend A, as shown in Fig. 1, cuts a relatively large diameter straight pipe made of stainless steel or steel at equal inclination angles that alternately incline positive and negative to the pipe axis. It is manufactured by obtaining a pipe body 1 with an elliptical joint part 2 of the same shape, and joining the joint parts 2 of the pipe body 1 by welding, etc., and the joint part 2 is made by joining the elliptical end faces. This created a corner, which had various effects on the fluid flowing inside the pipe.

For example, when seawater or the like is flowed into a pipe, there is a loss in the flow, especially at the corners of the joints on the outside of the vent, and shellfish, dirt, etc. tend to adhere, which changes the flow condition.

SUMMARY OF THE INVENTION An object of the present invention is to provide a miter bend manufacturing method that eliminates the above-mentioned drawbacks, eliminates corners at joints, and performs miter bending without adversely affecting the fluid flowing inside the pipe.

An embodiment of the present invention will be described in detail based on the drawings.

First, as in FIG. 1, a straight pipe is cut at alternately positive and negative inclination angles to the pipe axis so that the shapes of the end faces are equal. ! Obtain two tube bodies 1.

Next, as shown in FIG. 2, the diameter of the major diameter part of the elliptical end surface 2 of the tube body 1 is curved to J = uni, which is close to the diameter of the minor diameter part, to form a curved part 3, and then the tube body A cutout 4 is provided from the inner surface of the tube 1 to serve as a groove for welding, and the joint 2 is welded from inside the tube. At this time, the welded portion 5 is covered so that the thickness of the welded portion 5 is equal to the thickness of the tube body 1.

Although the curved portions 3 are formed at both ends of the major diameter portion of the elliptical end surface 2, they may also be formed only at the major diameter portion of the elliptical end surface 2 on the outside of the bend curve.

As described above, according to the present invention, a plurality of tube bodies whose joint portions are inclined to the tube axis are each curved so that the diameter of the elliptical end face of the joint portion is close to the diameter of the short diameter portion. By joining the joints at the joints, no corners will be formed at the joints after joining, and no fluid loss will occur due to the shape of the joints or the adhesion of dust or the like.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional side view of a conventional miter bend, FIG. 2 is a sectional view of a main part of a miter bend according to the present invention, and FIG. 3 is a half-sectional side view of the same. DESCRIPTION OF SYMBOLS 1... Pipe body, 2... Oval end surface, 3... Curved part,
4... Cut off, 5... Welded part. Figure 1 Figure 2

Claims (1)

[Claims] A plurality of tubes each having an elliptical end surface with a joint part inclined to the tube axis is created, and the long diameter part of the elliptical end surface of the tube body is curved so that its diameter is close to the short diameter part. A method for manufacturing a miter bend, characterized in that the body is joined at the joint portion.