JPS58132339A - Molding method of bellows - Google Patents

Abstract

PURPOSE:To mold a bellows efficiently, by interposing an outside circumferential wall of a base pipe between a male mold and a female mold, rotating the male mold, pushing the female mold into the male mold, and moving the male mold and the female mold in the axial direction, following the base pipe which contracts in the axial direction in accordance with its push-in quantity. CONSTITUTION:A base pipe 6 is fitted to a spline mandrel 1 having male molds 2a-c, and a part of its outside circumferential wall is interposed between the male molds 2a-c and female molds 4a-c. Subsequently, when push-in force is given to the female molds 4a-c in the direction as indicated with an arrow (y) and the spline mandrel 1 is rotated, a bellows 7 on which a crest-like part 7a and a trough-like 7b have been formed alternately is obtained on the outside circumferential wall of the base pipe 6. In this case, the base pipe 6 contracts in accordance with the push-in quantity of the female 4a-c, therefore, the male molds 2a-c and the female molds 4a-c also move in the axial direction accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of forming a bellows by forming an uneven portion on the outer circumferential wall of a blank tube made of a thin cylindrical body.

[Technical background of the invention and its problems]

Using a mold consisting of a male mold having an uneven portion and a female mold that engages with the uneven portion of the Jll type, the outer F! The male mold and thin cylindrical body were rotated while IIW was held between the ls mold and the female mold.

A bellows forming method is known in which an uneven portion is formed on the outer peripheral wall of a thin cylindrical body.

This molding method is used during molding (because the outer circumferential wall of the two-thin cylinder is pressed in the fine direction by the female die).

The thin cylindrical body is pulled in the axial direction according to the amount of pushing. Therefore, if it is attempted to mold a large number of concavo-convex portions at the same time, the outer peripheral wall of the thin cylindrical body will break, and it is difficult to form the concave-convex portions accurately at predetermined positions.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to be able to simultaneously form uneven portions at multiple locations on the outer circumferential wall of a blank pipe, thereby improving work efficiency. The purpose of this invention is to provide a method for forming bellows that will swell.

[Summary of the invention]

It consists of a plurality of male molds having uneven parts and a female mold that engages with the uneven parts of these male molds.The outer circumferential wall of the raw pipe is interposed between these storage molds and the female molds, and the male mold is rotated. The object is to prevent the mother tube from breaking by pushing it into the female male mold and moving it in the axial direction of the male and female molds as the raw tube contracts in the axial direction according to the amount of pushing.

[Embodiments of the invention]

The present invention will be described below based on an embodiment shown in the drawings. In the figure, reference numeral 1 denotes a spline mandrel, and its base end is connected to two drive sources (not shown) for rotational driving. , lc are fitted at equal intervals.

These are movable in the axial direction of the spline mandrel 1 and rotate together with the spline mandrel 1. Further, the male molds jm, 2b, and 2c are ring-shaped, and an uneven portion 3 is formed along the circumferential direction on the outer peripheral surface thereof. Also, 1s type 2m, 2b, 2
On the outside corresponding to c, there are female 94814b, 4c that move in the fine direction and axial direction of the spline mandrel 1.
is provided. And these female types 4a, 4b, 4
C has 2 male types, 2b.

A concavo-convex portion 5 that meshes with the concave-convex portion 3 of 2C is provided.

Next, a method of molding a bellows using the molding apparatus configured as described above will be explained. As shown in FIG. 1, the blank tube 6 consisting of a thin cylindrical body is
The spline mandrel 1 is fitted with a spline mandrel 1 having a
A part of the outer peripheral wall of the male mold 2a, 2b, 2c and the female mold 4a.

4b, 4c. Next, the female type 4m, 4
b, 4c in the direction of the arrow y and rotating the spline mandrel 1, as shown in Figs. 2 and 3.
As shown in the figure, the outer circumferential wall of the raw pipe 6 is formed by alternating ridges 7a and troughs 7h by the uneven parts 3 and 5.
l is obtained. At this time, the base pipe 6 is ill type 4m, 4b
, 4c, the male molds 2b, , 2G and the female molds 4b, 4c contract in the axial direction according to the amount of pushing.

is drawn to the X direction, male m2 b and female type 4b move by XI, and male type 2c and female type 4C move x@0
) Move only 2 x pieces of snow. therefore.

No tensile force is applied to the outer peripheral wall of the raw pipe 6.

Outside the base pipe 6! AI! Bellows will be formed at the same time in three locations.

In addition, in the above embodiment, the case where the bellows 7 is simultaneously formed at three locations on the outer circumferential wall of the raw pipe 6 has been described, but this is just one example, and the bellows 7 may be formed at two or four or more locations. Although the male molds 21.2b and 2c are formed in-house using the spline mandrel 1, the present invention is not limited thereto, and a cylindrical mandrel with a key embedded therein or a prismatic mandrel may be used.

〔Effect of the invention〕

As explained above, this invention involves interposing the outer circumferential wall of the blank pipe between the male mold and the female mold, pushing the male mold into the female mold while rotating, and moving the pipe in the axial direction according to the amount of pushing. Since the male and female shapes move in the axial direction as the tube contracts, even if bellows are formed at multiple locations on the tube at the same time, there will be no axial tensile force on the tube when the bellows is formed. This has the effect of preventing the material pipe from breaking and improving the efficiency of the bellows molding operation.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view of a forming apparatus, FIG. 2 is a longitudinal sectional side view showing a bellows forming state, and FIG. 3 is a sectional front view. 2a~2C...male type! ...Uneven parts, 14a to 4C...
・Female mold, 5... Uneven part, 6... Plain pipe, 7... Bellows Applicant's agent Patent attorney Shikihiko Suzue

Claims (1)

[Claims] Consisting of a plurality of male molds having irregularities along the circumferential direction on the outer peripheral surface, and a female mold that engages with the irregularities of these male molds,
The outer peripheral wall of the raw pipe is interposed between these male and female molds, and the female mold is pushed into the male mold while rotating the male mold, and the male and female molds move in the axial direction according to the amount of pushing. A bellows forming method characterized by: