JPS602488B2 - How to manufacture camshafts for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a camshaft for driving intake and exhaust cams of an internal combustion engine.

More specifically, it consists of a shaft and a cam ring such as a press-molded steel plate attached to the shaft, and a synthetic resin is filled between the shaft and the cam ring to integrally connect them, simplifying the production of the camshaft as much as possible. The present invention relates to a method for manufacturing a camshaft, which contributes to mass production and cost reduction, has sufficient accuracy for practical use, facilitates the formation of lubrication grooves, etc., and contributes to reducing metal noise such as that caused by camshafts. Conventionally, a camshaft for driving intake and exhaust cams of an internal combustion engine is generally a cast product manufactured by a casting method or a forged product manufactured by a forging method. At present, such conventional cast and forged products are first cut into predetermined dimensions by machining after forming the material, then subjected to heat treatment such as condensation, and then polished as a final finish.

These conventional methods require a large machining allowance for the material due to problems with the relative angle and shape of the cam, as well as the manufacturing method of casting and forging molds. Requires a process. Therefore, the number of man-hours required to manufacture the camshaft is extremely large, the work becomes complicated, and equipment such as a special grinder is also required, which increases the equipment cost, which is not favorable for the production of the camshaft. Moreover, this inevitably increases the cost of the camshaft. In addition, instead of the above, a combined type camshaft has also been proposed in which camshaft components prepared in advance using sintered metal are assembled onto the shaft and integrated by welding or the like.

However, even in this case, there are problems such as the need for finishing processing such as heat treatment and polishing after bonding, which is not desirable in camshaft production as described above.

In view of the above-mentioned problems in manufacturing conventional camshafts, the present inventors have created the present invention to effectively solve the problems.

The object of the present invention is to form a cam ring using a steel plate material separately from the shaft, and to attach the cam ring to the shaft and fill the gap with a heat-resistant and pressure-resistant synthetic resin. A method for manufacturing a camshaft integrally bonded with resin is provided.

Therefore, the object of the present invention is to streamline the production of camshafts by eliminating the need for rough grinding, finishing, etc. by machining unlike casting and forging methods, unlike conventional methods that require heat treatment, welding, etc. To provide a method for manufacturing a camshaft that is simple and convenient for mass production, improves productivity, and contributes to cost reduction of the camshaft.

In addition, the object of the present invention is to simplify manufacturing and improve mass productivity as described above, yet to achieve good accuracy.
In addition to obtaining a camshaft that is sufficient for practical use, the shaft and cam ring are integrally bonded using synthetic resin, so functionally it reduces as much as possible the driving metal noise of the cam and the drive unit, such as the sound of the cam. To provide a method for manufacturing a camshaft which is also effective in noise prevention.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows a side view of the camshaft, and the camshaft 2
0 consists of a shaft 1 formed into a predetermined length and a predetermined shape by casting, forging, etc., and a cam ring 10 obtained by press forming a steel plate material. A heat-resistant, pressure-resistant synthetic resin is filled between the cam ring 10 and the shaft 1,
A cam ring 10 and a shaft are integrally joined by synthetic resin.

As a result, a camshaft 20 having a large number of cams 21 extending in the axial direction on the shaft 1 is obtained as shown in FIG.

To explain in more detail, the cam ring 10 is made by hot pressing a ring-shaped SUS material or the like to give it a predetermined shape, dimensional accuracy, hardness, surface treatment, etc., and finish it with all the processing necessary for the cam 3. The product is preformed in a pre-assembled state.

The cam ring 10 is formed, for example, as shown in FIGS. 4 and 5, and the end face shape is, for example, partially bulged in the radial direction 11.
and the other portions are formed into a circular shape so as to fit together with the four circular portions of the supporting portion 2 (to be described later) of the shaft 1, and are formed with a width in the direction of the koji, and this width is determined in relation to the engaging portion of the driven member. The outer circumferential surface 12 constituting the cam surface of the cam ring 10, including the outer circumferential surface of the bulging portion 11, is determined by the required operation of the driven member and the intake/exhaust valves. The shaft 1 is formed by casting, forging, etc., and mounting portions 2 for the cam rings 10 are formed at predetermined positions in the axial direction of the shaft 1.

This mounting portion 2 includes, for example, a cam ring 10 as shown in FIG.
If so, it is formed in a similar shape and integrally includes a semicircular base 3 having a larger diameter than the outer diameter of the shaft 1 and a chevron-shaped bulge 4 in the radial direction, as shown in FIG. The outer dimensions of the portion 2 are set so that a sufficient clearance is formed between the outer circumferential surface 5 and the inner circumferential surface 13 of the cam ring 10 when the cam ring 10 is fitted thereon. Therefore, the mounting portion 2 does not require processing to achieve dimensional accuracy. A plurality of V-shaped grooves 6 are formed at appropriate locations on the outer periphery of the mounting portion 2, for example, on the outer periphery of the semicircular base 3 as shown in FIG. 3 and on the top of the bulging portion 4 as shown in FIG.

The cam ring 10 is mounted on the mounting portion 2 on the shaft, and both ends of the shaft in the axial direction are supported by jigs 30, 30 as shown in FIG. do.

Types 31 and 32 have shafts and cam rings 10 on the joint surfaces.
The storage recesses 33, 34 are symmetrically provided, and the recesses 33, 34 are symmetrically provided.
The shaft 1 and the cam ring 10 are housed in the recess 34, and the recesses 33 and 34 are set so as to strictly satisfy the accuracy and positioning of the relative angular relationship between the shaft date and the cam ring 10, the mounting position in the track direction, etc. With the shaft 1 and cam ring 10 housed, molds 31 and 32 are clamped to hold the cam ring 10 and shaft 1 with high precision.

As a result, a sufficient gap is formed between the inner circumferential surface 13 of the cam ring 10 and the outer circumferential surface 5 of the mounting portion 2 of the shaft 1, and the cam ring 10 is held in place. Next, the passage 3 formed in the molds 31 and 32
The cam ring 10 and the shaft attachment part 2 are connected through 6...
A heat-resistant and pressure-resistant synthetic resin, such as a fluororesin, is filled into the gap between the cam rings 10 from the axial end surface thereof at a melting temperature of 350°C.

In the illustrated example, the filled synthetic resin 35 bulges out to a predetermined thickness on the front and rear surfaces of the gap in all directions, and also continuously covers the end surfaces of the cam ring 10 and the shaft mounting portion 2, thereby forming a bond between the cam ring 10 and the shaft 1. The bond was strengthened, and furthermore, the intrusion of the synthetic resin into the concave grooves 6 caused the grooves to become wedged, thereby strengthening the bond between the two.

After cooling, the molds 31 and 32 are separated, and the burrs on the synthetic resin are removed.
Obtain the camshaft 20. The lubrication required for the cam can be easily formed on the inner surface of the cam ring 10, etc., since the connecting member is made of synthetic resin.

As is clear from the above, according to the present invention, a cam ring is formed in advance by press forming a steel plate material with the accuracy required for a cam, and this is attached to the shaft with loose iron, and the gap between the shaft and the cam ring is Since the camshaft is obtained by filling the gap with synthetic resin and joining and integrating the shaft and cam ring, there is no need for any machining such as rough grinding or finish grinding of the cam part as with conventional methods, making it possible to manufacture the camshaft. Dramatically simplify the process.

In particular, in the present invention, surface treatment is performed in advance at the ring stage,
A cam ring is formed that satisfies all of the hardness, dimensions, shape, etc., and is bonded with synthetic resin, so even when filling with synthetic resin, it is not exposed to high temperatures as in conventional heat treatment and welding, and therefore it is not heated. There is very little distortion due to
Therefore, there is no need for any machining such as finishing or straightening that is required due to distortion caused by heat treatment or welding, and it is possible to easily manufacture camshafts while maintaining sufficient precision for practical use. It contributes to labor saving, rationalization, and simplification of camshaft manufacturing, has excellent mass productivity, and also contributes to cost reduction.

Further, according to the present invention, even if the cam shape is changed, it can be easily handled by using the shaft as it is and changing the cam ring etc. without changing the equipment etc. Since synthetic resin is interposed between the cam ring and the shaft, it is possible to absorb metal noise such as evening noise, which is a major cause of noise in internal heat engines, and is effective in terms of noise control. Since the grooves are made of synthetic resin, they can be easily formed, and are very practical.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an explanatory side view of a camshaft, FIG. 2 is an enlarged partially cutaway side view of the same essential parts, and FIG. 4 is an end view of the cam ring, and FIG. 5 is a side view of the same. In the drawings, 1 is a shaft, 2 is a mounting portion, 10 is a cam ring, 20 is a force shaft, 31 and 32 are molds, 33 and 34 are concave portions, and 35 is a synthetic resin. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A cam ring that has been pre-finished and formed to the required precision as a cam is loosely fitted into the mounting part of a shaft on which a cam ring mounting part is formed at a predetermined position, and only the cam part is inserted into the shaft between the mounting part and the cam ring. A method for manufacturing a camshaft for an internal combustion engine, characterized in that the camshaft is formed by filling heat-resistant and pressure-resistant synthetic resin from the directional end face.