JPH0356813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a plunger for a valve brush adjuster that supports a rocker arm incorporated in a valve train of an engine.

Conventionally, this type of manufacturing method was
According to the publication, after forming oil holes b and c in the bottom and peripheral wall of a bottomed cylindrical material a as shown in FIG. A first pressing step of drawing to form a stepped shape having a tapered shoulder e for preventing the plunger from coming off, and forming an inverted cone in which the inner peripheral surface of the drawn opening end d is made thinner on the opening end surface side. A step of cutting into a shape, a second pressing step of drawing the cut open end d into a hemispherical seating surface f that receives the rocker arm, and a second pressing step that forms the swinging of the rocker arm into a portion adjacent to the seating surface f. It is known that a plunger for a valve brush adjuster is manufactured by cutting a permissible relief groove g, but in this method, a seat surface f is formed between the first press process and the second press process. Since the above-mentioned cutting process of the inner peripheral surface of the opening end d is added to facilitate the drawing process, the process cycle is bad from the viewpoint of productivity, and the press machine is not used for the first press process. It is necessary to install two machines, one for the second press process, and the equipment cost increases.
Furthermore, since the inner diameter of the opening end d is narrowed down to a small diameter in the first pressing process, this cutting process has to be performed using a small cutting tool without applying much cutting load, resulting in poor cutting efficiency. This has the disadvantage that chips and the like tend to remain on the surface, and cleaning after cutting is time-consuming.

An object of the present invention is to provide a manufacturing method that eliminates such inconveniences, and involves drawing a bottomed cylindrical material over a certain length on the open end side to form a tapered shoulder. In a method for manufacturing a plunger for a valve brush adjuster, the method includes a first pressing step of forming the plunger into a stepped shape, and a second pressing step of drawing the opening end into a hemispherical seat surface for receiving a rocker arm. It is characterized in that, prior to the first pressing step, the outer peripheral surface of the opening end is cut into a conical shape with a thinner wall on the opening end surface side.

Next, the present invention will be explained based on the drawings.

Referring to FIG. 2, A shows a plunger obtained by the method of the present invention, and the plunger A is inserted into a sleeve C with a one-way valve B assembled to its lower end, and a valve rush adjuster D is installed. This is assembled to the cylinder head E of the engine, and the rocker arm F is supported on the seat surface 6 (described later) of the plunger A, and oil is supplied to the oil chamber G at the bottom of the sleeve through the one-way valve B. The gap that occurs in the valve mechanism due to the inflow of water can be automatically corrected.

Here, the plunger A is prevented from coming off by a shoulder portion 5 and a ring H caulked to the upper end of the sleeve C, which will be described later.

Here, the manufacturing process according to the present invention is as shown in FIG.
cutting the outer circumferential surface of the material 1 into a conical shape with a thin wall on the open end surface side;
A first pressing step in which the material 1 is formed into a stepped shape having a tapered shoulder portion 5 by drawing the side over a certain length, and the opening end portion 4 is formed into a hemispherical seat surface for receiving the rocker arm F. 6, and a second press step of drawing and forming.

According to the drawing process in the first pressing process,
The conical shape of the outer peripheral surface is transferred to the inner peripheral surface by the flow of the meat at the open end 4, and the inner peripheral surface is formed into an inverted conical shape with a thinner wall on the open end surface side, and in the second pressing process, the same as in the conventional method A hemispherical seat surface 6 is formed on the surface.

In the first pressing process, a die having a tapered part for forming the shoulder part 5 and a small-diameter aperture hole continuous to the tapered part is used, and the open end part 4 is pushed into the aperture hole through the tapered part and apertured. During processing, when the press starts, the conical part on the outer periphery of the open end 4 comes into contact with the tapered part, and the open end 4 is accurately centered, that is, the conical part performs a guide function and the open end 4 is smoothly pushed into the drawing hole without causing misalignment, and the accuracy of drawing the opening end 4 is improved.

In addition, in the illustrated example, the portion adjacent to the seat surface 6 is formed into an undercut shape in the second press step, and this undercut shape portion 7 allows the rocker arm F to be easily swung without having to separately cut relief grooves as in the conventional method. To explain this in more detail, the second press step is carried out using a mold as shown in FIG. an upper die 9 which can be raised and lowered and which has a recessed spherical surface 9a facing the
A split die 10 is attached to the tapered hole 8a at the lower end to sandwich the upper part of the shoulder 5 from the side, leaving the open end 4. When the upper die 9 is lowered, the open end 4 is shaped into a hemispherical shape. When forming the seat surface 6 by drawing, the portion adjacent to the seat surface 6 is formed into a spherical shape having approximately the same diameter as the seat surface 6 or a slightly smaller diameter according to the shape of the upper inner edge of the split mold 10. The undercut-shaped portion 7 is formed. This is advantageous in that it does not create a thin part like the conventional relief groove g shown in FIG. 1, and a plunger with strong strength can be obtained.

As described above, according to the present invention, the opening end of the material is cut prior to the first pressing step of drawing the material into a stepped shape, and the opening end is shaped into a hemispherical seating surface. A cutting process is not added between the second press process and the first press process, and one press machine transfers the first press process and the second press process of the material that has undergone the first press process.
The pressing process can be performed at the same time, improving productivity and reducing equipment costs.
In the cutting process that precedes the pressing process, the outer circumferential surface of the opening end is cut, making it possible to cut large bits efficiently and simplifying the cleaning process by preventing chips from entering the material. The cone-shaped part cut into the outer peripheral surface of the opening end of the cloth functions as a centering guide in the first pressing process, making it possible to further improve productivity. Accuracy is improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the conventional manufacturing process, Fig. 2 is a cutaway side view of the plunger obtained by the present invention in use, Fig. 3 is a diagram showing the manufacturing process according to the present invention, and Fig. 4 is the same. It is a cut side view of the apparatus used for a 2nd press process. 1...Material, 4...Opening end, 5...Shoulder, 6
……seat.

Claims (1)

[Claims] 1. A first pressing process in which a bottomed cylindrical material is drawn over a certain length on the open end side to form a stepped shape with a tapered shoulder, and the open end is adapted to receive a rocker arm. In a method for manufacturing a plunger for a valve brush adjuster, which includes a second pressing step of drawing and forming a hemispherical seat surface, prior to the first pressing step, the outer circumferential surface of the opening end is thinned on the opening end surface side. A method of manufacturing a plunger for a valve brush adjuster, characterized by cutting it into a conical shape.