JPS583457B2 - Valve rocker shaft oil hole machining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for machining oil holes in a valve rocker shaft of an internal combustion engine.

More specifically, the valve rocker shaft is characterized in that the oil hole is punched with a two-stage punch having a cylindrical tip and a conical enlarged middle portion, and a conical chamfer is formed at the upper end opening of the oil hole. This provides an oil hole machining method.

As is well known, the valve rocker shaft is the pivot axis of the valve rocker arm that swings to provide opening and closing motion to the intake and exhaust valves of an internal combustion engine. The structure is such that lubricating oil is supplied from the internal pipe hole 5 of the rocker shaft 4 to the fitting contact surface 7 with the valve rocker arm 6 through the oil hole 2 and the chamfered portion 3.

Conventionally, the oil hole of the valve rocker shaft has generally been processed by drilling, but this drilling method uses the hole intersection where the inner surface of the pipe hole 5 intersects with the side surface of the drill hole. This method has the disadvantage that cutting burrs always occur in the case of No. 8.

When the engine is running, these cutting burrs often fall off and get mixed into the lubricating oil, and get into the sliding parts of rocker shafts and rocker arms as well as various bearing surfaces, causing seizure and abnormal wear. This sometimes causes abnormal noise in the engine, and sometimes the engine is forced to stop.

Therefore, it is necessary to completely remove the burr, but this type of burr occurs at the hole intersection 8 where the pipe hole and the oil hole intersect, and the size of the burr varies. The deburring tool was inserted from No. 5, but with this method, the burr would simply bend into the oil hole 2, leaving a portion that was not removed. If you try to remove it from the oil hole 2 again, it will return to its original state. It only returned to normal and could not be removed satisfactorily no matter how many times it was repeated.

Other deburring methods have been developed, such as a method using abrasive processing and an electrochemical method, but these methods have not yet been put to practical use because the burrs in question are of various sizes and are located within extremely narrow pipe holes. The company has not yet reached the pace of economic profitability.

Furthermore, the connecting part between the outer circumferential surface of the rocker shaft and the oil hole is chamfered, but this is functionally intended to facilitate the drawing of lubricating oil to the sliding surfaces of the rocker shaft and rocker arm, and also for machining purposes. When finishing the outer diameter of the rocker shaft by grinding, this is an essential process to prevent crescent-shaped burrs from forming on the oil holes and the outer surface of the rocker shaft.

Conventionally, this C-chamfering process was performed using a two-stage drill, and the oil hole was machined at the same time, or the drill C-face cutting process was performed in a separate process, but this cannot be said to be an economical method. .

Furthermore, in the case of drilling, the machined surface cannot of course be a uniformly smooth burnished surface.

Furthermore, in drill cutting, there is generally a limit to the distance between oil holes that can be machined at the same time depending on the size of the drill head and chuck part, and if the distance between adjacent oil holes becomes small, cutting may not be possible at once. This is not a possible solution.

The present invention has been devised in view of the above, and is an object of the present invention to provide an economical and effective method for machining oil holes in valve rocker shafts, thereby eliminating the various drawbacks of the prior art.

The present invention is characterized in that an oil hole is provided on the outer periphery of the valve rocker shaft by a two-stage punch whose tip portion becomes a cylindrical portion via a conical portion, and a conical chamfered portion is formed at the upper end opening of the oil hole. This is a method of drilling oil holes in valve rocker shafts.

To explain in detail the working order of the oil hole machining method of this invention based on the embodiment shown in FIGS. 2 and 3, the valve rocker shaft 4 is inserted into a sufficiently reinforced work holder 9, and the positioning pin Then, the valve rocker shaft 4 is clamped and fixed by a hydraulically pneumatically or mechanically driven fixing arm 11 at a position that limits the punching process.

The punch 1 is supported by a punch holder 13 at the tip of a slide 12, and the punch 1 is a two-stage punch in which the tip part passes through a conical part 1'' and becomes a cylindrical part 1'.

A cotter device 14 is installed inside the punch holder 13, so that the position of the punch 1 can be freely adjusted and the chamfer dimension 3 can be freely adjusted.

Therefore, when this punch 1 is pushed into the valve rocker shaft 4 as the slide 12 moves, an oil hole 2 is punched out in the cylindrical tip portion 1' of the punch 1.

If the punch 1 is further pushed in, the area around the entrance of the oil hole 2 in the conical portion 1'' is crushed to form a chamfered portion 3.

It goes without saying that these oil holes 2 and chamfered portions 3 are machined simultaneously by one reciprocation of the slide 12.

A uniform burr is generated at the hole intersection 8 where the punched oil hole 2 and the pipe hole 5 intersect and can be removed by an extremely simple deburring operation. It does not easily fall off and can be used as is.

In addition, if the wall thickness of the rough pipe material becomes large and the strength of the punch tip cannot withstand it, drill the part halfway in advance, then punch out the oil hole 2 with a two-stage punch and punch out the conical chamfered part 3. It may also be molded.

The oil hole machining method for a valve rocker shaft according to the present invention is to punch an oil hole 2 on the outer periphery of a valve rocker shaft 4 using a two-stage punch 1 whose tip part has a conical part 1'' and then a cylindrical part 1l. Since the conical chamfer 3 is formed at the upper end opening of the hole 2, punching of the oil hole 2 and forming of the chamfer 3 are simultaneously and easily performed by the pressing force of the puncher of the two-stage punch 1, resulting in extremely high precision. This method has the remarkable effect of stably and efficiently producing high-quality processed products with a high level of corrosion resistance and uniform material structure and mechanical properties.

And, as mentioned above, unlike the conventional drill cutting process, the problem of excess cutting material (burr) can be effectively solved,
Furthermore, the conical chamfer 3 is formed by the conical part 1'' of the two-stage punch 1, so that it always has a constant and proper shape and draws lubricant evenly to the sliding surfaces of the rocker shaft and rocker arm. Oil holes can be machined to increase the lubricity of sliding surfaces.

In addition, since the oil hole processing method of this invention is a punching press processing using a two-stage punch, the processed surface becomes a uniformly smooth burnished surface, which improves the circulation of lubricating oil and is also excellent in strength. .

Uniform burrs are generated by the punching process at the hole intersection 8 where the punched oil hole 2 and the pipe hole 5 intersect. In general, there is little chance of falling off, and it can be used as is.In any case, there is no need to finish cutting the inner surface of the pipe hole 5 at the hole intersection, making it extremely workable and efficient. It is economical and has great effects in terms of strength and lubricating functionality.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the installation of a valve rocker shaft with an oil hole provided therein, Fig. 2 is a longitudinal sectional front view of the state in which the oil hole has been punched out by a device embodying the present invention, and Fig. 3 is a longitudinal sectional side view of the same. . 1...Punch 1'...Tip cylindrical part, 1''...Conical part, 2...Oil hole, 3... Chamfered portion, 4... Valve rocker shaft, 5... Pipe hole, 6...
・Valve rocker arm, 7...Mating contact surface,
8... Hole intersection, 9... Work holder, 10... Positioning pin, 11...
Fixed arm, 12... Slide, 13...
...Punch holder, 14...Kotter device.

Claims (1)

[Claims] 1. An oil hole is punched on the outer periphery of the valve rocker shaft using a two-stage punch whose tip has a conical shape and a cylindrical tip, and a conical chamfer is formed at the upper end opening of the oil hole. Oil hole machining method for valve rocker shaft.