JPS6318111A - Manufacture of builtup cam shaft - Google Patents

Abstract

PURPOSE:To improve the workability of connection of an annular detachable piece with a hollow shaft, by locating in a metal mold the detachable piece mounted on the hollow shaft, and swaging the hollow shaft in its axial direction under the clamped condition to thereby expand the hollow shaft in diameter and connect the detachable piece with the hollow shaft. CONSTITUTION:In assembling a cam shaft, a cam piece 3 having a desired cam profile is located at a predetermined position of a hollow shaft 2, and this assembly is set in a lower metal mold 12. Then, an upper metal mold is fitted to the assembly, and both the metal molds are clamped. Then, under the clamped condition, opposed shaft end pressers 13 and 1 are so forced as to approach to each other until they are stopped by the metal molds, so that the hollow shaft 2 is swaged to be expanded in diameter. At this time, the hollow shaft 2 is shortened in its entire length, and is correspondingly expanded in diameter without a decrease in wall thickness. The expansion of the hollow shaft 2 causes that the outer circumference of the hollow shaft 2 is brought into tight contact with the inner circumference of a through-hole of the cam piece 3, and that annular projections are formed on the hollow shaft 2 on opposite sides of the cam piece 3 to ensure the connection of the cam piece 3 with the hollow shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a hollow tube material as a camshaft of an internal combustion engine, and utilizes upsetting and expansion to form separate cam pieces, bearing pieces, shaft end pieces, etc. The assembly relates to an assembled camshaft with fixed pieces.

As a camshaft assembled using conventional technology bulge processing, the
5-46767 etc.

Problems to be Solved by the Invention The method of assembling an annular shaft into a hollow shaft by inserting a piece, expanding the hollow shaft by bulging, and joining the pieces together has the following problems.

■ Since the hollow shaft is filled with fluid, the machining cycle time is long and production efficiency is poor.

■ Due to internal pressure expansion, cracks occur in the pipe wall.

■ The wall thickness of the expanded pipe section decreases, resulting in a decrease in strength.

Means for Solving the Problem: The hollow shaft is assembled into an annular mold by inserting a piece into the mold, and then the hollow shaft is upturned in the axial direction using a mold closing mold MK to expand the hollow shaft. For assembly, join the pieces.

(By upsetting the hollow shaft), the hollow shaft is shortened in the axial direction and expanded without reducing the wall thickness, and the piece is joined to the hollow shaft for assembly.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a cam piece 3 as an assembly piece according to the embodiment.

The cam piece 3 is approximately formed with a desired cam profile ζ by casting, forging, or sintering, and has an annular shape provided with a through hole 5 through which the hollow shaft 2 before diameter expansion can be inserted.

A suitable chamfer 6 is provided at the intersection of the side surface of the cam piece and the through hole 5.
, 7 are applied.

1 and 2 illustrate the upsetting and joining process of the assembled camshaft 1. In the figures, 2 is a hollow shaft such as a steel pipe, which is prepared in advance to be longer than the desired camshaft overall length. 1
1 and 12fi This is an assembly mold divided into upper and lower parts. The outer peripheries of the upper mold 11 and the lower mold 12 are received by a mold holder (not shown).

The inner peripheries of the upper and lower molds 11 and 12 are carved to a large size for the desired camshaft, and shaft end pressers 18 are provided at both ends of the mold.
．． 15 are arranged facing each other.

The shaft end presser 13 and the shaft end presser 15 are configured to be able to press the hollow shaft 2 so as to shorten it in the axial direction by a hydraulic cylinder (not shown).

When assembling the camshaft, first insert the cam piece 3 into a predetermined position on the hollow shaft 2, set it in the lower mold 12, then fit the upper mold and close the mold by applying pressure so that the upper and lower molds come into close contact with each other. do.

Then, with the mold closed, the two shaft end pressers 13, 15 are pushed in the direction toward each other until they are stopped by the mold, which is what is called upsetting and expanding the hollow shaft 2.

Then, the entire length of the hollow shaft 2 is shortened, and the hollow shaft 2 bulges out to the outer periphery without reducing its wall thickness. Due to this bulge, the outer periphery of the hollow shaft 2 comes into close contact with the inner peripheral surface of the through hole 5 of the cam piece 3, and an annular protrusion 18 is formed on the side surface of the cam piece, so that the cam piece 3 is attached to the hollow shaft 2. Joined.

After the assembled camshaft 1 thus assembled is removed from the mold, the rainbow cam profile surface 4 and the journal portion are ground and finished as necessary, and oil and water are applied to complete the assembly.

In addition, if a higher bonding strength between the hollow shaft 2 and the cam piece 3 is required, the cam piece 3 may be temporarily attached to the above-mentioned upsetting/expanding connection, and the cam shaft 1 may be removed from the molds 11 and 12. After taking them out, the cam piece 3 and the hollow shaft 2 may be reinforced by brazing, beam welding, diffusion bonding, or the like.

Effects As described above, according to the present invention, it is possible to
The hollow shaft is shortened in the axial direction and the tube is expanded without reducing the tube wall thickness, and during assembly the piece is joined to the hollow shaft, so unlike internal pressure tube expansion, cracks occur in the tube wall and the shaft strength decreases. There is no

Furthermore, since the joining process only involves pressing the shaft end, the process cycle is short and production can be extremely efficient.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a partially sectional plan view showing a state in which each part is placed in a mold and the mold is closed. FIG. 2 is a partial cross-sectional plan view of the assembled camshaft that has been joined within the mold. FIG. 3 is a projection view of the cam piece as an assembly piece. (Explanation of symbols) 1...-m vertical camshaft. 2...middle
Empty axis. 3...--The assembly is a piece (cam piece). 11, 12...
・・・－・Mold.

Claims (1)

[Claims] The annular assembly piece 3 is inserted into the hollow shaft 2 in the molds 11 and 12, and then the hollow shaft 2 is mounted in the mold closed state.
A method of manufacturing an assembled camshaft, which comprises upsetting the hollow shaft 2 in the axial direction, expanding the tube, and joining an assembly piece 3 to the hollow shaft 2.