JPS60258421A - Remelting and hardening method of cam shaft - Google Patents

Abstract

PURPOSE:To remelt and harden easily and inexpensively the whole width of a cam by rotating the cam shaft, and supplying the arc of a vibrating torch to the whole width at every site of the cam surface having varying width. CONSTITUTION:A cam shaft 1 having cams is rotated, and a plasma torch 5 emitting plasma arc 6 from a nozzle part 5a, which is positioned at regular intervals from the cam surface 2a whose cam top 3 and cam base 4 have different width, is vibrated in the direction parallel to the axis of the cam shaft 1. While the torch follows the zigzag course A on the cam surface 2a, a cam 2 is remelted and hardened. In said process, the amplitude of the vibration of the plasma torch 5 is allowed to correspond to the width of the cam surface 2a, and the whole width at every site of the cam surface 2a can be treated. Consequently, the cam surface 2a having varying width can be remelted and hardened.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for remelting and hardening a camshaft, in which when the width of a cam surface is wide or narrow, the whole width is remelted and hardened to match the width.

(Prior Art) A remelting hardening treatment method has been put into practical use as a surface hardening treatment for the cam surface of a cam in a camshaft incorporated in an automobile engine. In the remelting hardening treatment method, an arc is applied to each cam surface of a preheated camshaft using a plasma torch or the like to chill it and form a hardened layer on the cam surface. In such remelting and hardening treatment, the camshaft is usually rotated and the plasma torch is reciprocated multiple times within the width of the cam surface, thereby remelting the entire cam surface while drawing a meandering trajectory. Ta.

By the way, the shape of each cam of the camshaft is usually such that the width of the cam surface is wide at the cam base (5l) and gradually narrows as it reaches the cam top (52), as shown in FIG. There is. This is due to the draft angle during casting. Therefore, when vibrating the plasma torch (53), the cam top (52)
) The plasma torch (53) was repeatedly moved back and forth on all cam surfaces at this constant width based on the width of the cam base (51). (51a) occurs. In order to solve this problem, in conventional lace processing, in order to match the width of the cam top (52) and the width of the cam base (51), the part that spreads in the width direction of the cam base (51) is cut out and remelted and hardened. Methods have been considered, such as applying heat treatment or re-melting and hardening at a constant amplitude as described above, and then removing the non-chill-hardened portions by grinding, etc., but both methods require laborious work. , the problem of high cost was raised.

(Object of the Invention) The present invention provides a method for remelting and hardening a cam of a camshaft, and when there is a wide or narrow width of the cam surface between the cam top and the cam base of the cam, the width of each cam surface is Accordingly, a melting arc is supplied to the entire width of the cam surface, and even if the width of the cam surface of the cam is wide or narrow, the entire width can be remelted and hardened, and this can be done at low cost with a simple configuration. With the goal.

(Structure of the Invention) The present invention provides a method for remelting and hardening the cam surface by rotating a camshaft and vibrating a torch facing the cam surface in the cam width direction. The gist of the present invention is that at some point, the arc generated by the torch can be supplied to any part of the cam surface over the entire width thereof.

(Embodiment) A preferred embodiment of the present invention will be described below based on the accompanying drawings.

In FIG. 1, (1) is a camshaft, and this camshaft (+) is built into an automobile engine, and usually has a plurality of cams integrally formed at required intervals. In FIG. 1, one of the cams (2) is shown. The above-mentioned force shaft (1) is arranged so as to be freely rotatable around the camshaft.

In addition, the cam width of the cam (2), that is, the width of the cam surface, is different between the cam top (3) and the cam base (4) as shown in FIG. It is formed so that it is wider than the cam top (3) and gradually narrows as it reaches the cam top (3).

For example, a TIG torch, plasma torch (5), etc. (hereinafter referred to as plasma torch) connects the nozzle portion (5a) to the cam surface (2a) of the cam (2).
2a). The plasma torch (5) freely moves up and down according to the height change of the rotating cam (2), and the cam shirt (1)
It moves freely in the horizontal direction in the figure so as to be parallel to the axis of. Means for moving the plasma torch (5) is omitted in the figure.

Further, an electrode is built into the nozzle portion (5a) of the plasma torch (5), and a plasma arc current is supplied to this electrode from a plasma power source. When a plasma arc current is supplied to the electrode of the plasma torch (5), a plasma arc (6) is generated between the nozzle part (5a) and the cam surface (2a), and this plasma arc (6) ) with cam (2
) by melting and then chilling the cam surface, the cam surface is subjected to remelting and hardening treatment.

In the remelting hardening process, the camshaft (1) rotates and the plasma torch (5) repeats reciprocating motion in the cam width direction, so the plasma torch (5) meanders on the cam surface (2a) of the cam (2). Perform the remelting and hardening process while drawing the trajectory (A). In this case, the plasma torch (5)
The amplitude of the reciprocation is made to correspond to the width of the cam surface of the cam (2), so that it spans the entire width at any point on the cam surface. That is, the plasma torch (5) is connected to the cam base (4).
) to re-melt the cam base (0) by reciprocating it with a large amplitude in accordance with the cam width of
As it approaches the cam top (3), its amplitude gradually decreases in response to changes in the cam width. Then, when passing the cam top (3) and approaching the cam base (4), the amplitude increases again. Thus the plasma torch (5
) changes in response to changes in the width of the cam surface being remelted, and the plasma torch (5) is moved such that the amplitude always matches the full width of the cam surface. The horizontal movement of the plasma torch (5) is controlled by a control device in synchronization with changes in the cam surface facing the nozzle portion (5a) of the plasma torch (5).

According to the embodiment described above, even though the cam surfaces of the cam (2) have widths and widths, the remelting and hardening process can be performed on the entire width of all the cam surfaces.

Next, a second embodiment of the present invention will be explained based on FIGS. 2 and 3. In this embodiment, the plasma arch (15)
A magnetic coil (16) is installed in parallel to the arc emitted from the plasma torch (15).
6) applies a magnetic field at appropriate timing. The plasma torch (15) reciprocates with respect to the cam surface in the width direction of the cam, and in this embodiment, the plasma torch (15) reciprocates over the entire cam surface with a constant width determined by the cam width of the cam top (3). When remelting a wide part of the cam base (such as 0) other than the cam top (3), use a plasma torch (15
) The remelting and hardening process is performed on the entire width of the cam surface by oscillating only the plasma arc (6) at both ends of the amplitude. The horizontal swing of the plasma arc (6) is carried out by periodically passing a pulse current through the magnetic coil (16), and by passing a pulse current through the plasma torch (15).
This is done at appropriate timing when the are located at both ends of the reciprocating motion. Also, since the width of the cam gradually changes, the fourth
As shown in the figure, it is necessary to adjust the amount of current to the magnetic coil (16) and change the amplitude of the plasma arc (6) according to the width, and at the right end of the amplitude of the plasma torch (15), , At the left end, there is a plasma arc (6) to the left.
Since it is necessary to shake the magnetic coil (16), the current direction in the magnetic coil (16) is adjusted as appropriate.

According to the second embodiment, even if the cam width is wide and narrow and varies, the remelting and hardening process can be performed on the entire width of the cam surface at any location on the cam surface.

(Effects of the Invention) As is clear from the above description, according to the present invention, even if the width of the cam of the camshaft to be remelted and hardened is not constant, the wide portion of the cam can be removed. This method has the advantage that remelting and hardening treatment can be applied uniformly to all cam surfaces of wide and narrow cam widths, and that this can be done with a simple configuration and cost reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a front view of a cam showing a first embodiment of the present invention, FIG. 2 is a front view of a cam showing a second embodiment of the present invention, FIG. 3 is a diagram showing the relationship between a plasma torch and a magnetic coil, and FIG. FIG. 4 is a diagram showing the relationship between the cam surface and the amount of current applied to the magnetic coil, and FIG. 5 is a front view of the cam for explaining the conventional remelting hardening process. In the drawing, (1) is the camshaft, (2) is the cam, and (3) is the camshaft.
, (52) are cam tops, (4) and (51) are cam bases, (5), (15) and (53) are plasma torches, and (16) is a magnetic coil. Patent applicant Honda Motor Co., Ltd.

Claims (3)

[Claims] (1) In the method of remelting and hardening the cam surface by rotating the camshaft and vibrating a torch facing the cam surface in the cam width direction, if the width of the cam of the camshaft is wide or narrow, A method for remelting and hardening a camshaft, characterized in that an arc generated by a torch is supplied so as to cover the entire width of any part of the cam surface. (2) The remelting and hardening method according to the patent, characterized in that the amplitude of the torch is made to correspond to the width of the cam so that it matches the width of the cam. (3) A method for remelting and hardening a camshaft according to claim 1, characterized in that the amplitude of the torch is constant, and the arc is oscillated at both ends of the reciprocating motion of the torch. .