JP2001193422A - Poppet valve for engine and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a stem of a poppet valve by plastic working for lightening the weight of the poppet valve. SOLUTION: The poppet valve is divided into a shaft shaped stem and a disk shaped valve plate which are welded with each other, and the stem is composed of a cylindrical shaft part molded through plastic working, a wall thickness cotter end formed on one end of the shaft part, and a wall thickness flare part formed on the other end. The stem is manufacture, in such a way that a steel plate is formed in a stepped cylindrical pipe through throttle working, and its stepped part is extended into an elongated shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a poppet valve used as an intake and exhaust valve of an engine.

[0002]

2. Description of the Related Art As is well known, an engine poppet valve includes a stem that slides in a valve guide and an umbrella-shaped valve plate provided at one end of the stem. Are made from separate materials and are integrated by friction welding. The stem is generally made of a rod-shaped steel material.However, in an aircraft engine, in order to reduce the weight of the stem, the stem material is drilled into a hollow cylindrical shape, and sodium is sealed in the inside. Are known. On the other hand, recently, in small engines for vehicles, efforts have been made to reduce the diameter of the shaft as small as possible in order to reduce the weight of the poppet valve, reduce the burden on the valve spring, and enable high-speed operation. ing.

[0003]

However, there is a limit in strength in making the stem of the stem thinner, and in order to further reduce the weight, titanium and other expensive materials must be used. Had become. It was not considered that the stem could be formed not only by machining, but also by thin-drawing or plastic working such as ironing, but it was not possible to form an elongated stem with only deep-drawing. It was difficult. In addition, the handling length alone becomes too long and the molding is difficult only by the handling process.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a shaft having a stem and a disk-shaped valve plate welded to each other, wherein the stem is formed into a tubular shape by plastic working. In the above, the flare portion formed on one side of the stem portion of the stem and the thick shaft portion formed on the other side are solved by a poppet valve formed thicker than the tubular shaft portion. In this case, the welding is preferably friction welding, and the thick shaft portion is preferably formed in a part of a small diameter portion slightly smaller than the outer diameter of the stem portion of the stem. As a manufacturing method, a tubular semi-finished product having a bottom formed by drawing a plate material with a stem welded to a valve plate is used, and the bottom end of the semi-finished product is squeezed to a small diameter of at least 2 mm. The problem can be solved by providing a step of forming a semi-finished product having a step and a step of treating the outer diameter of the two steps to form a stem portion of the stem and a small diameter portion formed at the end thereof. Where,
Preferably, a flare portion is formed by expanding the vicinity of the terminal end at the end of the step of handling the stem of the stem.

[0005]

[Function] The stem welded to the valve plate is made thin by processing the stem part occupying most of the length direction and the small diameter part formed at one end of the stem part, and is made lightweight. Can be Also, the impact when the poppet valve is seated, near the cotter groove of the flare portion or small diameter portion to be welded, or the end of the small diameter portion that is hit by the rocker arm or valve lifter is made thick and reinforced. I have. The stem is manufactured by plastic working. Here, the outer diameter of the semi-finished product made by deep drawing is divided into a stem portion and a small-diameter portion of the stem and processed. Flare parts, thick shaft parts and end faces are not subjected to handling processing, or handling processing is performed lightly. The thickness at the time of deep drawing remains as it is.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. In FIG. 1, reference numeral 10 denotes a poppet valve according to the present invention. The poppet valve 10 is a cylinder head 11 of the engine.
Is provided to open and close a port 13 that opens to a combustion chamber 12 formed in the first chamber. Reference numeral 14 denotes a valve seat, and a port 13
Are provided at the open ends. Reference numeral 15 denotes a valve spring that urges the poppet valve 10 to the closed position, and 16 denotes a valve operating cam that opens the poppet valve 10 against the elasticity of the valve spring 15. 17 is a valve lifter, 18 is a valve guide which slidably supports the poppet valve 10, 19 is a valve cotter, and a spring retainer 19
a to the shaft end of the poppet valve 10. In addition,
The configuration of the engine described above is not much different from a conventionally known configuration.

In the present invention, as shown in FIG. 2, the poppet valve 10 includes a disc-shaped valve plate 20 and the valve plate 20.
Consists of a stem 30 friction-welded to the center of the stem. Valve plate 2
Numeral 0 is made of heat-resistant steel, and has a conical valve portion 21 seated on the valve seat 14 at the peripheral edge thereof, and a combustion chamber 1
The surface facing 2 is recessed into a shallow sphere along the inner surface of the combustion chamber. In addition, a material having a high temperature hardness such as stellite may be overlaid on the valve portion 21 as necessary.

The stem 30 is integrally connected to the valve plate 20 by friction welding, and has a tubular stem 31 that reciprocates in the valve guide 18 by sliding. A flare portion 32 whose outer diameter increases in a quadratic curve from the shaft portion to the end is formed at one end of the stem portion 31 of the stem, and the stem 30 is formed by the expanded end of the flare portion 32. It is friction welded to the valve plate 20. In this embodiment, a neck portion 38 having a slightly smaller diameter is provided between the stem portion 31 and the flare portion 32 of the stem, but this is not an essential component for the poppet valve 10. The other end of the stem portion 31 of the stem has a small-diameter portion 34 slightly smaller in diameter than the shaft portion.
The end of the small diameter portion 34 has a thick shaft portion 36 whose inner diameter is reduced in order to provide a cotter groove 35 and whose wall thickness is larger than the remaining portion.
Reference numeral 37 denotes a thick end surface that closes the shaft end of the thick shaft portion 36.

Next, the stem 3 to be welded to the valve plate 20
0 will be described. The production of the stem 30 is shown in FIG.
As shown in (a), a disk-shaped material 41 manufactured by a first step of punching a stainless steel plate by a press machine is used. In the second step, the raw material 41 is deep drawn by a press machine to form a first semi-finished product 42 having substantially the same thickness as a whole as shown in FIG. The first semi-finished product 42 has a bottom 42 which forms the end face 37 with the flange portion 42a.
It consists of a cylindrical part 42c with b. The first semi-finished product 42 has a basic shape to be processed later.

The first semi-finished product 42 is further subjected to a drawing process in a third step and a fourth step to preform the small diameter portion 34. In the third step, as shown in FIG. 3C, a slightly smaller step 42d is formed by deep drawing. Subsequently, in the fourth step, as shown in FIG. 4D, the small-diameter stepped portion 42d is supported by a smaller-diameter die (not shown), and the inner diameter portion is tapered (not shown). To increase the thickness of the thick end face 37 and form a second semi-finished product 43 having three steps 42c, 42d, 43b on the outer periphery. The second semi-finished product 43 is a basic form of a handling process to be performed subsequently.

In the fifth step, the second semi-finished product 43
As shown in (e), the three steps 42c, 42d,
43b, the middle step 42d is replaced with the small diameter step 4
3b, the length of the middle step portion 42d is extended, and at the same time, the thickness is reduced, and the diameter is changed to a thin small-diameter portion 34. In this step, the step portion 43b forming a part of the small-diameter portion 34 is changed to the thick-walled shaft portion 36 while the initial thickness is substantially maintained, and the outer shape of the small-diameter portion 34 is formed.

Next, in the sixth step, as shown in FIG. 3 (f), the second semi-finished product 43 treats the outer diameter of the large-diameter step 43b to be substantially the same as the diameter of the middle step 42d. As the diameter is reduced, the length is elongated and the stem 31 of the stem is formed. At the end of this handling process, the flare 32
As a preparatory step for making the above, the flange portion 42a is bent outward in the axial direction by a handling mold (not shown). In the seventh step, the flange portion 42a and the outer periphery of the small-diameter portion 34 are subjected to spinning in the seventh step to form the hollow flare portion 32, and the cotter groove 35 is prepared as shown in FIG. After forming, the plastic working of the stem 30 is completed. In addition, since the flare portion 32 is not subjected to the working process, the shaft portion has a large thickness, which is a melting allowance for a subsequent welding process. In addition, the neck 38 may have a smaller diameter by spinning.

The stem 30 thus formed is connected to the valve plate 20 by friction welding. That is, FIG.
When the flare portion 32 is pressed against the back surface of the valve plate 20 shown in (a) as shown in (b) and rotated at a high speed, the end of the thick flare portion 32 is melted by frictional heat. As a result, the impurities at the joints are pushed outward, resulting in a strong connection as shown in FIG. After removing welding burrs from the third semi-finished product 45 thus completed, the valve 21
The cotter groove 35 and the end face 37 are finished by grinding, and the poppet valve 10 is completed. Welding can be projection, flash butt, inert gas arc, etc.

The poppet valve 1 manufactured as described above
0 indicates that the stem 31 and the small-diameter portion 34 of the stem 30 formed by drawing or handling are formed into a thin, hollow tube without uneven thickness, so that the light-weight poppet valve 10 is obtained as a whole. . Also, since the stem 30 is made thin, there is no significant increase in weight even if the outer diameter is increased.
Light weight and high rigidity can be obtained. Since the stem 30 is welded to the valve plate 20 by the flare portion 32 whose outer diameter is smoothly increased, a long welding length is obtained and a high welding strength is obtained. Furthermore, since the stem 30 has the thick shaft portion 36 at the end of the small diameter portion 34, the stem 30 has strength enough to withstand severe impacts received from the valve lifter 17 and the valve cotter 19, despite being made entirely lightweight. Hold.

The stem 30 constituting the poppet valve 10 is
It is made by plastic working from a plate material. In this case, first, an elongated basic shape is adjusted by drawing, and the vicinity of the cotter groove 35 which receives a strong surface pressure and the valve plate 20 where stress concentration is likely to occur.
Except for the welded portion (flare portion 32), the remaining portion is thinly stretched and manufactured by working, so that the material yield is good and the manufacturing cost of parts can be kept low.
Further, by processing the longitudinal direction of the stem 30 separately into the stem portion 31 and the small diameter portion 34 of the stem, a longer stem can be thinned.

[0016]

According to the poppet valve of the present invention, not only the stem portion is simply hollow, but also the wall thickness can be made extremely thin, and a lightweight and rigid poppet valve can be obtained. Further, since the inner surface of the flare portion formed at one end of the stem is hollow, the weight is further reduced. If the poppet valve is manufactured by the manufacturing method of the present invention, a stepped pipe having a substantially constant wall thickness is formed by drawing, and the straight pipe portion with less stress is thinned by ironing, so that the poppet is lightweight and has excellent strength. Valves can be manufactured. And so on.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an engine using a poppet valve according to the present invention.

FIG. 2 is a side view showing a poppet valve taken out.
(A) is a side view, (b) is the BB sectional view.

FIG. 3 is a process diagram showing a process of manufacturing a stem of a poppet valve.

FIG. 4 is a process diagram showing a manufacturing process after a valve plate and a stem of a poppet valve are combined.

[Explanation of symbols]

 10 Poppet valve 11 Cylinder head 12 Combustion chamber 13 Port 14 Valve seat 15 Valve spring 16 Valve cam 17 ····· Valve lifter 18 ···· Valve guide 19 ···· Valve cotter 19a ···· Spring retainer 20 ······ Valve plate 21 ······ Valve part 30 ······· Stem 31 ···・ Stem shaft part 32 ・ ・ ・ ・ ・ ・ flare part 34 ・ ・ ・ ・ ・ ・ small diameter part 35 ・ ・ ・ ・ ・ ・ cotter groove 36 ・ ・ ・ ・ ・ ・ thick shaft part 37 ・ ・ ・ ・ ・ ・ end face 38 ・ ・ ・ ・ ・ ・ neck part 41 ・ ・ ・··· Material 42 ··· First semi-finished product 42a ··· Flange part 42b ··· Bottom 42c ··· Cylindrical part 42d ··· Small diameter step 43 ··· Second semi-finished product 45 ··· Third semi-finished product

Claims (5)

[Claims] 1. A stem having a shaft stem and a disc-shaped valve plate welded to each other, wherein the stem is formed into a tubular shape by plastic working. A poppet valve for an engine, wherein a flare portion formed on one side and a thick shaft portion formed on the other side are formed thicker than the cylindrical shaft portion. 2. An engine poppet valve according to claim 1, wherein said welding is friction welding. 3. An engine poppet valve according to claim 1, wherein said thick shaft portion is formed in a part of a small diameter portion slightly smaller than an outer diameter of a stem shaft portion. 4. A cylindrical semi-finished product having a bottom formed by drawing a plate material into which a stem to be welded to a valve plate is formed, and the bottom end of the semi-finished product is squeezed to a small diameter at least. A method for manufacturing a poppet valve, comprising: a step of forming a stepped semi-finished product having two steps; and a step of treating the outer diameter of the two steps to form a stem portion of a stem and a small-diameter portion formed at an end thereof. . 5. The method according to claim 4, wherein the flare portion is formed by expanding the vicinity of the end at the end of the step of handling the stem of the stem.