JPS58131036A - Molding method of bellows - Google Patents

Abstract

PURPOSE:To hold the outer periphery of a tube stock uniformly and prevent a swing, by holding the outer peripheral wall of the tube stock between a freely rotatable male mold having a concave and convex part along the direction of its circular periphery and an engaging female mold and forming a bellows by pushing the mold of a same shape as the female mold for a swing rest so as to match the push in amount of the female mold. CONSTITUTION:A tube stock 6 is fitted onto a mandrel 1, a part of the outer peripheral wall of the tube stock 6 is placed between a male mold 3 and a female mold 5 and also the concave and convex parts 7a, 8a of the swing rests 7, 8 are contacted to the outer peripheral wall of the tube stock 6. A push in force is added to the female mold 5 in an arrow direction a and the male mold 3 is rotated together with the mandrel 1. Then, a bellows 9 is obtained by forming a hill part 9a and a valley part 9b alternately on the outer peripheral wall of the tube stock 6 by the concave and convex parts 2, 4. In this time, the swing rest molds 7, 8 are pushed in to the arrow direction b matching the push in amount of the female mold 5, the concave and convex parts 7a, 8a engage with the bellows 9 and the swing of the tube stock 6 is prevented by the cooperation of the female mold 5 and the swing rest molds 7, 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bellows forming method in which a bellows is formed 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 die with an uneven part and a female die that engages with the uneven part of the male die, the outer circumferential wall of a thin cylindrical body, which is a raw pipe, is held between the male die and the female die, and rotated. However, in the circumferential direction, one uneven part is inconvenient.Therefore, in the past, there was a method in which a guide roller was provided in contact with the outer circumferential surface of the thin-walled cylindrical body to prevent deformation during molding of the thin-walled cylindrical body. Although this method has been adopted, it has the disadvantage that it cannot effectively prevent runout.

[Purpose of the invention]

This invention was made in view of the above circumstances, and its purpose is to provide a bellows forming method that can prevent the deflection of the raw tube during bellows forming and form highly accurate bellows. That is.

[Summary of the invention]

In this invention, a steady rest mold having the same shape as the female mold is disposed on the raw pipe on the same cross section as the female mold, and this steady rest mold is applied to the female mold by the pushing amount (=total Push,
The aim is to hold the raw pipe evenly from its outer circumference to prevent it from wobbling.

[Embodiments of the invention]

Not shown. ) and rotates in the direction of the arrow.A male mold 3 having an uneven portion 2 along the circumferential direction is formed in a part of the mandrel 1. Also, on the outside corresponding to the male die 3, there is a concavo-convex portion 4 that engages with the concave-convex portion 2 of the male die 3.
A female die 5 having a shape is provided so as to be movable in the axial direction of the mandrel 1. Between the male die 1 and the female die 5 is a blank tube 6 made of a thin cylindrical body fitted onto the mandrel 1.
A peripheral wall is interposed. Furthermore, a first steady rest mold 1.8 is disposed on the outer periphery of the blank pipe 6 on the same cross section as the female mold 5.These first and second steady rest molds 7 .8 has a female mold 5 on the outer periphery of the raw pipe 6 (21
1 = uneven parts 'Is, am are formed so that the angle is 20°, and the pushing amount of the female mold 5 in the arrow-IQ direction is 3.
2 together in the direction of the arrow (-).

Next, a method of forming a bellows using the forming apparatus configured as described above will be explained.The raw pipe 6 is fitted onto the mandrel l (:), and a part of the outer circumferential wall of the raw pipe C is Intervening between type 3 and female type 5 (second, first
, the uneven parts 1 m and 8 m of the second steady rest type 7°8 are connected to the base pipe 6.
contact the outer peripheral wall of the In this state, move the female mold 5 in the direction of arrow a]
When a pushing force is applied to the male mold 3 and the mandrel 1 is rotated, the outer circumferential wall of the blank tube 6 is formed into alternating peaks 91 and valleys 9b due to the uneven parts 2 and 4.
A bellows 9 is obtained. At this time, according to the pushing amount of the female mold 5, the first. Since the second steady rest mold 2.8 is pushed in the direction of the arrow, the uneven parts 7a and 8a engage with the molded bellows 9, and the deflection of the blank pipe 6 during molding is prevented by the female mold 5 and the first, Cooperation L with the second steady rest type 1.8 is thus prevented.

Note that the number of steady rest molds for preventing swinging of the blank pipe is not limited to two, but may be one, or may be pressed in one step so as to be mechanically interlocked with the female mold.

〔Effect of the invention〕

As explained above (2) In the method of forming a bellows by pressing a female male base while rotating together with a male base pipe, the female base is inserted into the base pipe on the same cross section as the female base. A steady rest mold of almost the same shape is provided, and the steady rest mold is pressed in the axial direction of the raw tube in accordance with the pushing amount of the female mold during molding. It is possible to hold the pipe, prevent the material pipe from swinging out, and form a bellows with high precision without causing deformation or crushing.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional side view of a molding device, FIG. 2 is a longitudinal sectional side view of the molding state, and FIG. 3 is a sectional front view.

Claims (1)

[Claims] It consists of a rotatable male die with an uneven part along its circumferential direction, and a female die that engages with the uneven part of the male die, and between the male die and the female die (= with the outer peripheral wall of
In the method of forming a bellows by pushing the female mold into the male mold while rotating the male mold, a steady rest mold having substantially the same shape as the female mold is disposed on the base pipe on the same cross section as the female mold, A 40-S molding method characterized in that the steady rest mold is molded by pushing the female mold into the amount (1 in total, in the axial direction of the raw tube).