JPH04334708A - Manufacture of hollow valve - Google Patents

Abstract

PURPOSE:To lighten the hollow valve and to reduce the manhours. CONSTITUTION:A hole 10c is bored along an axis from an end surface 10b at a valve 10 stem 10a by means of a drill 11, and then, a cotter groove 10d is formed at a predetermined position by means of a rolling roller 12, and next, a hollow valve 10 is completed by conducting the polishing finish of the stem.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing hollow valves.

0002

[Prior Art] Generally, in order to draw a valve lift curve defined by a cam in a valve train of an engine, the valve lift (mm) vs. load (kg) characteristic diagram shown in FIG. Spring force P (=P1
+kx), the inertia force P'(
=(w/g)α(Nπ/60)2) must be small. Here, k: spring constant, x: lift amount, w:
Valve train weight, g: gravitational acceleration, α: lift curve acceleration, N: rotational speed.

[0003]Furthermore, recently, with the increase in the output of engines, the engine speed has also increased, and as shown by curve III in FIG. 4, the inertial force P' has also tended to increase. In order to increase the inertial force P', the spring force P is generally increased, but increasing the spring force P causes an increase in friction, so it is not a good idea. The best way is to reduce the weight of the valve train. In order to reduce the weight of a valve train, it is effective to reduce the weight of the valve, which accounts for about 50 to 80% of the weight, and therefore, attempts are being made to make the valve hollow.

Conventional hollow valves are shown in FIGS. 5(a) and 5(b).
As shown in the figure, the valve stem 1a and stem head 1b of the valve 1 are formed separately, a hole 1c is drilled in the axis of the stem 1a with a drill 2, and a hole 1c is formed in the axis of the stem 1a with a drill 3.
A hole 1d with the same diameter as the hole 1c is bored in the axis of stem 1a.
and the stem head 1b (c), and form a cotter groove 1e in the upper part of the stem head 1b using the cutting tool 4 (d).
), the welded stem 1a and stem head 1b are polished using a grindstone 5 (e) to form the hollow bulb 1.

In order to further reduce the weight, after polishing (e) with a whetstone 5, a drill 6 is drilled from the upper end surface of the stem head 1b to make the cotter groove 1e smaller in diameter than the hole 1d. After drilling the hole 1f (f) and communicating it with the hole 1d, the open end of the hole 1f is expanded (g) to the same diameter as the hole 1d using the drill 7 to form the hole 1g, thereby reducing the weight of the stem head 1b. I am trying to achieve this.

[0006]

[Problems to be Solved by the Invention] However, the conventional method for manufacturing hollow valves requires a large number of processing steps as shown in FIGS. 5(a) to (e) or (a) to (g). The cost is high, and there are problems such as the fact that the weight of the valve is not sufficiently reduced because the weight of the stem head is not sufficiently reduced.

The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a method for manufacturing a hollow valve that requires fewer processing steps and can further reduce the weight.

[0008]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a hole is formed in the stem of a valve from the end face along the axis, and then a rolling roller is placed at a predetermined location on the stem. After forming the cotter grooves, the stem is polished to produce a hollow valve.

[0009]

[Operation] A hole is bored in the stem of the valve along the axis from the end face, and then a cotter groove is formed at a predetermined location on the stem using a rolling roller, and then the stem is polished. This makes it possible to further reduce the weight of the valve, especially the stem head.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1(a), after the valve 10 is fixed to a processing machine (not shown), an end surface 10b is attached to a stem 10a.
A hole 10c is then drilled in the shaft center using a drill 11. This hole 10c is set to have a diameter and depth that allows the stem 10a to have sufficient strength and to allow maximum thinning in order to reduce the weight of the valve 10. After completing the drilling process on the stem 10a, while rotating the valve 10, a rolling roller 12 is pressed against the upper part of the stem 10a, that is, at a predetermined position near the end surface 10b, and an annular cotter groove 1 is formed along the circumferential direction.
0d is molded (b). By forming the cotter grooves 10d by rolling after forming the holes 10c in the stem 710a, that is, after making the stem 710a hollow, it becomes easy to form the cotter grooves 10d. This cotter groove 10d is temporarily finished.

Next, as shown in Figure (c), the cotter groove 10d formed in the stem 10a is accurately finished into a predetermined shape using a cutting tool 13. In addition, in the case where the cotter groove 10d can be accurately finished by the rolling roller 12 in FIG. 3(b), the machining by the cutting tool 13 is not necessary, and therefore the number of machining steps can be reduced accordingly.

The valve 10 has a cotter groove 1 in the stem 10a.
After 0d is formed, the stem 10a is polished by a polishing machine, for example, the grindstone 14. In this polishing, the valve 10 is rotated and the stem 10a is brought into pressure contact with the grindstone 14 to achieve a perfect circle finish. In this way, the hollow bulb 10 is formed. As a result, in the valve 10, the stem and the stem head are integrally formed, and the valve 10 is made as thin as possible.

This hollow valve 10 is applied to an OHC type valve mechanism in which the shaft end load acts in a plane and a line because the upper end 10b of the stem 10a is an open end. For example, as shown in FIG. 2, a valve lifter 15 is attached to the upper end of the stem 10a of the valve 10, and the valve lifter 1
5, or as shown in FIG. 3, one end 17a is swingably supported by the lash adjuster 18, and the other end 17b of the rocker arm 17 has a central roller 19 pressed against the cam 16. The upper end 10 of the stem 10a of the valve 10 is attached to the lower surface of the valve 10 via the slide pad 20.
This is applied to a type of valve train mechanism in which b is pressure-welded. Incidentally, this hollow valve 10 exhibits great effects especially when applied to an intake valve.

[0014]

[Effects of the Invention] As explained above, according to the present invention, a hole is formed in the stem of a valve from the end face along the axis, and then a cotter groove is formed at a predetermined location on the stem using a rolling roller. By polishing the stem,
The process of welding the stem is eliminated, and the drilling process using a drill is also reduced, which reduces the number of processes.Furthermore, by combining the hollowing of the stem with the rolling process, it is easier to form the cotter groove. It has excellent effects such as being able to be even lighter than conventional products and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a method for manufacturing a hollow valve according to the present invention.

FIG. 2 is a sectional view of a main part of a valve train to which the hollow valve of FIG. 1 is applied.

FIG. 3 is a sectional view of a main part of a valve train to which the hollow valve of FIG. 1 is applied.

FIG. 4 is a characteristic diagram showing the relationship between lift and load of the valve train.

FIG. 5 is a diagram showing a conventional method for manufacturing a hollow valve.

[Explanation of symbols]

10 Hollow valve 10a Stem 10c hole 10d　cotter groove 11 Drill 12 Rolling roller 13 Cutting tool 14 Whetstone 15 Valve lifter 17 Rocker arm 20 Slide pad

Claims (1)

[Claims] [Claim 1] A hole is bored in the stem of the valve along the axis from the end face, and then a cotter groove is formed in a predetermined location of the stem using a rolling roller, and then the stem is polished. Method of manufacturing hollow valves.