JPS60129464A - Cam piece and method of producing same - Google Patents

Abstract

PURPOSE:To reduce weight of a cam piece, by forming an outer circumference of the cam piece into a cam shape, providing recesses smaller than the outer circumference and similar thereto on both end surfaces, and forming a through-hole for a shaft at a central portion of the cam piece. CONSTITUTION:A cam piece 2 is engaged with a hollow shaft 4 of a cam shaft 1 so as to have a combining force sufficient to transmit a rotational force of the cam shaft 1 to a tappet. The cam piece 2 has an outer circumference and a cross section similar to those of a normal cam piece, and is provided with recesses 2a substantially similar to the outer circumference on both end surfaces. The cam piece 2 is further provided with a through-hole 2b for the shaft 4, and the through-hole 2b is formed with a mesh portion 2c engaged with the shaft 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an improvement in a cam piece coupled to a hollow shaft and a method for manufacturing the same.

Φ) Conventional technology and problems In general, the camshaft of an internal combustion engine suffers from a lot of wear because the cam part slides in contact with the rocker arm and tappet, so Jurai chills only the sliding surface. Cast iron camshafts are often used.

However, the Young's modulus of cast iron is 10,000 to 12,000.
Since the weight is as low as kg/mm2, cast iron camshafts have no choice but to have thicker shafts to increase rigidity.
It has the disadvantage of being heavy. In addition, the cast iron camshafts are chilled by applying a chiller (cold metal χ) to the cam sliding surface, but in addition to variations in quality, they are also subject to harsh usage conditions, such as carbon particles. Diesel engines, where the oil is contaminated, and engines that use leaded gasoline, where the oil is contaminated with lead compounds, have the problem of high wear.

Conventionally, there has been a method of brazing other parts to a steel pipe (Japanese Patent Application Laid-open No. 1986-6456) as a method for reducing the weight and improving the wear resistance of the cam part as described above. In this method, the members constituting the camshaft and the support jig made of refractory material are placed in a high-temperature atmosphere furnace and brazed, which requires large equipment and is difficult to work with and economically.

Also, Special Publication No. 46-21299, Special Publication No. 56-506
Although there is a disclosure in No. 1, etc. of connecting a cam piece to a hollow cam shaft by expanding the tube, it is difficult to put it into practical use and is not actually used.

(c) Purpose of the Invention It is therefore an object of the present invention to provide a cam piece with a rotating portion that is lightweight.

Structure of the invention In order to achieve the above object, the first invention is as follows:
The cam piece connected to the hollow shaft has a cam-shaped outer periphery, and has recesses on both end faces that are smaller than the outer periphery shape and have a similar shape to the outer periphery shape, and has a recess for the shaft. A through hole is provided, and the second invention is a method for manufacturing a cam piece coupled to a hollow shaft. A concave portion having a shape substantially similar to the outer peripheral shape was formed by cold or warm plastic working, a through hole for the shaft was then formed, and an engaging portion was further provided in this through hole.

(E) Examples of the invention Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 shows a camshaft 1 using a cam piece 2 according to the present invention.
In the side view, a predetermined number of cam pieces 2 are attached to the hollow shirt l-4.
After arranging the journal 3 at a predetermined position, the shaft 4 is expanded by, for example, press-fitting a tube expansion rod into the shaft 4, and the meshing portion (for example, serrations, knurling, sawtooth-like unevenness, etc.) provided on the cam piece 2 2C into the shaft 4,
The cam piece 2 is fitted to the taper throat (not shown) with sufficient coupling force to transmit the rotational force of the camshaft 1.

The cam piece 2 according to the present invention is illustrated in FIG. 2 (dl and 3), for example.
As shown in Figure (d), the outer circumferential shape and cross-sectional shape are similar to those of a normal cam piece, and both end faces have recesses 2a that are almost similar to the outer circumferential shape, and a through hole for the shaft 4. It has a hole 2b, and this through hole 2b is provided with a meshing portion 2C for coupling with the shaft 4. The shape of the engaging portion 2C needs to be determined in consideration of plastic deformation of the material forming the shaft 4 when the shaft 4 is expanded. In this example, the mountain angle is 90°, the height is 0,
．． Serrations of 5n+m were provided.

As is clear from FIGS. 2(d) and 3(d), the cam piece 2 has a thinner wall at the recess 2a compared to a normal cam piece, so its weight is reduced by about 1/3. It is ideal for today's automobile power supplies, which require weight reduction. Moreover, since the connecting portion with the shaft 4, that is, the engaging portion 2c, is in a state of biting into the shaft 4 due to the tube expansion, it has the strength and durability required for a camshaft, and the connecting means is the same as the tube expansion of the shaft 4. It is easy to implement.

Next, a method for manufacturing the cam piece 2 according to the present invention will be explained.

First, as shown in FIG. 2 (a) and FIG.
Prepare. This element body 1O is formed by any means such as cold or warm scale forging, thick plate punching, or drawing. Next, Fig. 2(b) and Fig. 3
As shown in Figure (b), four parts 11 which are smaller than this element body 10 and have a substantially similar shape to this element body 10 are provided on both end faces of this element body 10 by cold forging using a press. and,
As shown in FIG. 2(C) and FIG. 3 (C1), the thin wall portion 11a formed by the recess 11 is punched out using a press, for example, to provide a through hole 12 along the circular portion Llb of the four portions 11.

Therefore, a portion of the thin wall portion 2d remains in the cam portion 2f of the recess 11. Finally, serrations 2C are provided in the through hole 12 in the axial direction by plastic working.

According to this manufacturing method, (al~(
Since the three steps shown in d) are sufficient, the cam piece 2 can be easily obtained. Furthermore, since most of the work can be done by cold plastic working, continuous mass production is possible.

The cam piece according to the present invention is not limited to the cold plastic working method as in the above embodiments, but can also be manufactured by means such as sintering, cutting, and casting.

In addition, in the above embodiment, an example of a cam piece used to connect a cam piece to a hollow shaft by expanding the shaft was shown, but brazing can be used to connect a cam piece to a shaft by means such as brazing. If the cam piece used is
It is also not necessary to form an engaging portion in the through hole.

(F) Effects of the Invention As described above, the cam piece according to the present invention has four parts similar to the outer peripheral shape of the cam formed on both end faces thereof. Therefore,
It is extremely lightweight compared to conventional cam pieces, reducing the weight of the vehicle itself and achieving the low fuel consumption that is currently required. Furthermore, since most of the manufacturing method according to the present invention can be carried out by cold plastic working, it is suitable for mass production, with good workability and no risk of major damage to equipment. Particularly, in the cam piece of the present invention, if the part to be joined to the shaft, that is, the side wall of the through hole for the shaft is formed by a meshing part, there are requirements for the camshaft even if the part to be joined to the shaft is thin. The mechanical strength can be maintained. Therefore, it is particularly effective as a cam piece used in manufacturing a camshaft that connects the shirt 1- and the cam piece by expanding a hollow shaft.

[Brief explanation of drawings]

Fig. 1 is a side view of a camshaft using a cam piece according to the present invention, Fig. 2 +a) to (d) and Fig. 3 (11) to (d).
) is an explanatory diagram without showing the manufacturing process of the cam piece according to the present invention. ■...Cam shirt 1~. 2...Cam piece, 3...Journal.

Claims (4)

[Claims] (1) In the cam piece connected to the hollow shaft,
A cam having a cam-shaped outer periphery, and having concave portions on both end faces that are smaller than the outer periphery shape and have a shape substantially similar to the outer periphery shape, and a through hole for the shaft. pieces. (2) The cam piece according to claim 1, wherein an engaging portion is formed on the side wall of the shaft through hole. (3) The meshing part is □ serrated □ unevenness, knurling. The cam piece according to claim 2, which is a serration or the like. (4) In a method for manufacturing a cam piece that is coupled to a hollow shaft, a concave portion is formed on both end surfaces of an element body having a cam-shaped outer periphery, the shape being smaller than the outer periphery and having a shape substantially similar to the outer periphery. 1. A method for manufacturing a cam piece, which comprises forming the cam piece by cold or warm plastic working, then forming a through hole for the shaft, and further providing an engaging portion in the through hole.