JPS59197327A - Working method of thin walled cylinder - Google Patents

Abstract

PURPOSE:To produce stably a thin walled cylinder having good accuracy by spinning a cylindrical blank material inserted onto a mandrel while exerting an axial tension thereon then expanding the material. CONSTITUTION:A forming part 1c and an expanding part 1d having the diameter larger than that of said part are formed to a mandrel 1. A cylindrical blank material 3 is inserted onto the mandrel 1. When the material 3 is rolled in contact with a roll 2 and the mandrel 1, the material 31 is pulled backward at a specified speed via a chuck 4 by a puller so that an axial tension is exerted thereon. The material is formed by tube spinning in this state to a thin walled cylinder 3' and is expanded as it is by the part 1 to eliminate residual stress and at the same time to unify the inside diameter of the cylinder constant. The thin walled cylinder having good accuracy and straightness is obtd. by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for processing a thin-walled cylinder, and is intended to enable manufacturing of a thin-walled cylinder with good shape accuracy.

To produce a thin cylinder from a thick cylinder material, tube spinning is used to form the cylinder.

This tube spinning process is shown in Figures 1 (a) and (b).
) T-Explain while referring to. In both figures, the state before processing is shown in the upper half, and the state after processing is shown in the lower half. First, in the case of "backwards ironing", as shown in Fig. 1(a), the thick cylindrical material 3 inserted into the mandrel 1 is brought into contact with the rear end surface 1a of the mandrel 1, and While pressing the cylindrical material 3 with the roll 2, the mandrel 1
is rotated to form a thin cylinder 3'. In the case of "forward ironing", one cylindrical material 3 is hooked onto the tip end surface 1b of the mandrel 1, and similarly rotary formed using the rolls 2 to form a thin cylinder 3'.

By the way, in the conventional tube spinning process shown in FIGS. 1(a) and 1(b), the shape accuracy of the thin-walled cylinder 3' is ensured to the extent that it fits, but it still has the following drawbacks.

+l) The l# degree of the final product is greatly influenced by the roughness of the cylindrical material 3 in the pre-processing. In particular, if the clearance between the cylindrical material 3 and the mandrel 1 before processing is not within a specified range, the accuracy will vary greatly.

(2) When the degree of working increases, the elongation after working decreases significantly due to the influence of work hardening, and therefore annealing is required at an intermediate stage of working. The cylindrical material 3 after annealing is curved and has a distorted diameter, and the diameter is not necessarily constant and has large variations.

Among the above-mentioned variations, the one with the largest variation is the inner diameter accuracy (or circumference length: for thin-walled cylinders, the roundness changes depending on how they are placed, so it is more important to match the circumference lengths!).

However, the variation in the inner diameter is about 0 for a 200φ cylinder.
．． 6D below 21φ, most of which are 0.111m1φ
That's about it. Therefore, it is thought that the problems in the pre-processing and annealing steps can be further reduced, and an inner diameter accuracy of about 0311 is possible.

In view of the above-mentioned prior art, the present invention provides a stable and accurate thin cylinder even when the pre-processing of the cylindrical material is rough and the inner diameter accuracy is poor, or even when the dimensional variation of the cylindrical material is large. The object of the present invention is to provide a method for processing thin-walled cylinders that can be manufactured. The structure of the present invention that achieves this object is to perform tube spinogging while applying axial tension to the cylindrical material inserted around the outer periphery of the mandrel, and then
It is characterized by being expanded to a predetermined size.

Examples of the present invention will be described in detail below. As shown in FIG. 2 (the upper half shows the state before processing, and the lower half shows the state of rotation during processing), the mandrel 1 used in this example has a large diameter. The magnifying section 1d is making a sound. In this embodiment, a thick cylindrical material 3 is inserted into the mandrel 1 and processed together. In this case, depending on the bending process, the inner diameter may necessarily be smaller than the molded part 1c, but if the land (parallel part) of the expanded pipe part 1d is made small) and the introduction angle is set, the cylindrical material 3 will yield when inserted. The internal pressure of the reservoir (
The cylindrical material 3 is not difficult to insert because the ball friction force is also small and the insertion of the cylindrical material 3 is not difficult.

At the start of processing, when the cylindrical stack 3 comes into contact with the rolls 2, it is further narrowed down to reduce its diameter, and is rolled between the sockets 2 and 1 to be elongated in the axial direction. The roll 2 has an introduction angle υ for squeezing the cylindrical material 3, so the inner diameter only decreases, and since it is not rolled, it does not expand in the circumferential direction (the inner diameter increases). However, since the thin-walled cylinder 3' rolled by the rolls 2 does not have constant internal conditions, the inner diameter accuracy varies. Therefore, since the inner diameter accuracy cannot be satisfied as it is, the tube is expanded until the thin-walled cylinder 3 passing through the expanded tube portion 1d of the tome and mandrel 1 almost yields in the circumferential direction, and the inner diameter accuracy after machining is kept constant.

Next, the processing method of this embodiment will be explained with reference to FIG. 2 according to the processing procedure. When the cylindrical material 3 is inserted into the mandrel 1 and rolled by the rolls 2, it is first narrowed down to reduce the cylindrical diameter, and rolling starts from the moment it contacts the mandrel 1. In this narrowing down, the cylindrical material 3 is the roll 2 - mandrel 1
This continues until both are touched. Therefore, the cylindrical diameter of the unprocessed part in front of the roll does not require much mold cost. The reason for this is that the accuracy of the inner diameter of the leg can be ensured by expanding the tube later. When the cylindrical material 3 comes into contact with the roll 2/mandrel 1 and is rolled, it elongates mainly in the axial direction, but also tends to elongate to some extent in the circumferential direction (increase in diameter). It is necessary to pull it backwards at a constant speed all the way through. This tensile speed is mainly determined by the addition to - (to, to: wall thickness of processed surface, t: wall thickness after processing). When the tensile speed change is slow, the rolled material swells in the circumferential direction, increasing the diameter after forming, and a portion also acts to increase the flow diameter in front of the roll. Also, if the speed is too high, it will break. When processed at an appropriate tensile speed, the molded product will have a t
-1 close contact, and the diameter is 0.1 to 0.2 larger.

In this state, there are large variations in accuracy (in the state of curved tube expansion), and there is a large residual stress on the outer surface in the circumferential direction, so when cutting a thin cylinder 3', there are many problems such as the cut part spreading outward. .

For this reason, after being formed into a thin cylinder 3' by the rolls 2, the tube is expanded in the expansion section 1d to eliminate residual stress and at the same time make the inner diameter of the cylinder constant. Since all of the machining is done under tension, the molded product not only has good cylindrical accuracy but also good straightness.

As described above in detail with the embodiments, according to the uninvented method, a stable product can always be obtained without being affected by defects caused by iYI processing or annealing.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are explanatory diagrams for explaining tube spinning processing according to the prior art, and FIG. 2 is an explanatory diagram for explaining the present invention in detail. In the drawing, 1 is the manodrel and 1c is the molded part. 1d is the expanded tube part, 2 is the roll, and 3 is the cylindrical part. 3' is a thin cylinder. Patent applicant: Mitsubishi Heavy Industries, Ltd. Ryomei Giken Co., Ltd. Sub-agent patent attorney: Shibu Mitsuishi (and one other person)

Claims (1)

[Claims] A method for processing a thin-walled cylinder, characterized in that the tube is spun while applying tension in the axial direction to a cylindrical material inserted around the outer periphery of a mandrel, and then the tube is expanded to a predetermined size.