JPH036850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Object of the Invention The present invention relates to a method for manufacturing a drive shaft.

Traditionally, automotive driveshafts have been manufactured by swaging or drawing pipe material, but this conventional method allows for smooth adjustment of the wall thickness of the material transitioning from the base tube to the shaft. The wall thickness of the shaft was insufficient to provide the required strength such as torsional strength, fatigue strength, and bending strength, and damage occurred due to material or shape defects. Since a pipe opening remains at the end, the opening had to be sealed by plugging or welding.

Therefore, it is an object of the present invention to provide a new manufacturing method that eliminates the drawbacks of the conventional methods.

2. Structure of the Invention The manufacturing method of the present invention will be explained based on examples shown in the drawings.

A is a tube to be molded, and 1 is a predetermined clamp chuck for fixing this tube, and a tapered surface 1' is formed at the inner circumferential corner of the mouth end of the clamp chuck. A die 2 corresponds to the end face of the clamp chuck 1, and the shape of this die differs in each process. Therefore,
In order to distinguish the dies 2 in each process, the symbols are used as die 2a in the first process, die 2b in the second process, die 2c in the third process, and die 2d in the fourth process. Reference numeral 3 denotes a mandrel provided in the center of the die 2 in parallel with the die, and a base 4 is provided at the base end of this mandrel inserted into the tube body A for sliding back and forth on the surrounding die wall. There is. The shape of this mandrel 3 is different in each process, so in order to distinguish the mandrel 3 in each process, the reference numeral is the mandrel 3a in the first process and the mandrel 3 in the second process.
In step b and the third step, a mandrel 3c is used. Further, since the shape of the base 4 is different in each step, in order to distinguish the mandrel 3 in each step, the reference numerals are used as base 4a in the first step, base 4b in the second step, and mandrel 4c in the third step.

Next, the manufacturing process using the above configuration will be explained step by step.

First step: A long tube to be formed is attached to the clamp chuck 1 and fixed. (See Figures 1 and 6) Second process The outer diameter of the die 2a used here matches that of the clamp chuck 1, but its inner diameter is larger than that of the clamp chuck 1. . That is, the inner circumferential diameter of the die 2a is set to a length equal to the length of the material thickness that is to be expanded outward at the end of the tube body A. Further, the diameter of the mandrel 3a matches the diameter of the tube body I to be inserted.

Therefore, after moving the die 2a to the outer periphery of the end of the tube A that has come out from the clamp chuck 1 as shown in FIG. Insert the mandrel 3a into. Then, the inner circumferential surface of the end of the tube is placed on the mandrel 3.
a will now be supported, but as the mandrel 3a continues to move, the base 4a at the rear end will press the tube end, so the tube end will move toward the inner circumference of the die 2a, where there is sufficient space around it. , and eventually completely fills the space of the die 2a. The symbol a indicates the outward bulge at the end of the tube. (Figures 2 and 7
(See figure) Third step The die 2b used here has an outer circumferential diameter that matches that of the clamp chuck 1, and an inner circumferential diameter that also matches that of the clamp chuck 1. However, the diameter of the mandrel 3b is smaller than the diameter of the clamp chuck 1, and is formed to have a wide diameter in consideration of the thickness of the material to be expanded inward at the end of the tube. A tapered surface 2 is formed on the inner peripheral corner of the mouth end of this die 2b.
b′ is formed.

Therefore, first, the mandrel 3b is inserted into the tube end having the external bulge a as shown in FIG. comes into contact with. Thereafter, the die 2b is moved to slowly press the periphery of the outward bulge a at the end of the tube from the tapered end surface 2b' of the die 2b. Then, the outward bulge at the end of the tube is pushed back in the inner circumferential direction by the external pressure from the die 2b, and eventually completely fills the space between the die 2b and the mandrel 3b. The symbol Ib indicates the inner bulge at the end of the tube. (See Figures 3 and 8) Fourth step The outer diameter of the die 2c used here matches that of the clamp chuck 1, but its inner diameter is larger than that of the clamp chuck 1. . That is, the inner circumferential diameter of the die 2c is set to a wide diameter in consideration of the material that is to be further expanded outward from the end of the tube having the inwardly bulging portion Ib shown in FIG. Further, the diameter of the mandrel 3c matches the diameter of the inwardly bulging portion ib at the end of the tube body.

Therefore, after moving the die 2c with a gap on the outer periphery of the tube end having the inner bulge part b shown in FIG. Insert 3c. Then, the mandrel 3c supports the inner circumferential surface of the end of the tube, but if the mandrel 3c is moved as it is, the base 4c at the rear end strongly presses the end of the tube, so the end of the tube moves around it. It expands toward the inner periphery of the die 2c, which has ample space, and eventually completely fills the space of the die 2c. The symbol Ic indicates the re-bulging portion at the end of the tube body. (See Figures 4 and 9) Fifth step The die 2d used here has an outer diameter that matches that of the clamp chuck 1, but its inner diameter and outer opening are the same as that of the clamp chuck 1. The inner opening, which matches the inner diameter but tapers 2d' inward from the inner diameter, has a diameter that is about one-half that of the outer opening.

Therefore, the die 2d is now moved to the end of the tube body having the re-expanded portion Ic shown in FIG. As the pipe is inserted, the entire circumference of the end of the pipe becomes gradually narrowed, and then the opening of the end of the pipe is completely closed by the inner diameter of the die 2d, and the end of the pipe is closed. A thick closed wall is formed.
(See FIG. 5) The tubular body A thus completed has the form shown in FIG. 10.

Note that if the minimum outer diameter portion of the end of the tube is subjected to drawing in multiple stages, excellent torsional strength can be exhibited.

3 Effects of the Invention Since the present invention is such a manufacturing method, a drive shaft having a predetermined inner thickness at the shaft end can be manufactured from a single tube through a relatively simple process. Since the wall thickness and shape of the shaft from the original tube can be determined freely through calculation and practice, it is possible to obtain the optimum strength, and also to completely seal the shaft end. Therefore, post-processes such as plugging and welding are completely unnecessary, and the overall manufacturing cost can be reduced, which has extremely large effects.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and include FIGS. 1 to 5.
The figures are front sectional views showing each manufacturing process, and FIGS. 6 to 10 are half-cut front views of the tube corresponding to the manufacturing processes shown in FIGS. 1 to 5.

Claims (1)

[Claims] 1. A step of expanding the end of the tube outward to a required length,
A process of conversely bulging this outward bulge inward, a process of bulging the rear end of this inward bulge outward again and thickly, a step of bulging this outward thick bulge A method for manufacturing a drive shaft comprising the steps of expanding inward again and closing to form a thick closed wall.