JP2001234714A - Poppet valve and press forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce weight by decreasing the wall thickness of a sliding part without impairing the strength of a flare part in forming a poppet valve by press forming. SOLUTION: In this poppet valve, a sliding part of a stem is formed to be hollow and thin, and the wall thickness of the flare part connected to the sliding part of the stem is formed thicker than the sliding part of the stem. In a press forming method, a metal plate is drawn to form a cup-like material having a cylindrical wall formed with the substantially same diameter as the end diameter of the flare part, and a bottom wall closing one end thereof, and the material is ironed from the bottom wall to the open end of the cylindrical wall by several pairs of ironing dies formed by a punch and a die to reduce the diameter and simultaneously expand in the axial direction, thereby forming a flange part having several steps at the open end of the cylindrical wall. The flange part is clamped by a metal mold to form the flare part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a poppet valve for press-forming a steel plate and forming the same, and a press-forming method.

[0002]

2. Description of the Related Art Conventionally, there has been known an engine in which a poppet valve of an engine is made hollow and sodium is sealed therein. In addition, the applicant previously described a method of manufacturing a poppet valve of an engine mainly by using a press working. As a method, a stem of a poppet valve is slidably supported by a valve guide and a flare portion connected to the sliding portion. (Japanese Patent Application No. Hei 11-373363) was proposed in which plastic processing was performed and a disk-shaped valve element was friction-welded to the flared portion.

[0003] In this case, the end face of the flare portion was pressed against the side surface of a disk forming a valve body, rotated while being welded by frictional heat.
In this welding method, first, iron oxides and other impurities attached to the surface are removed by friction, and iron parts are rubbed, so that a stronger connection is performed as compared with welding by electricity or gas.

[0004]

However, if the flare portion is too thin, when the flare portion is pressed against the valve body and rotated, the flare portion will buckle due to surface pressure, and sufficient pressure contact force will not be obtained. In some cases, a sufficient bonding strength could not be obtained. In addition, to avoid buckling of the flare portion, it is sufficient to increase the plate thickness, but if the plate thickness of the flare portion is increased,
The thickness of the stem also increases at the same time, which reduces the weight of the stem. Also, if the flare is too thin,
When heated by the combustion gas, the rigidity of the valve body becomes excessively low, and the degree of adhesion between the seating surface and the valve seat is reduced, which may result in poor starting of the engine or reduced durability. Such problems can be solved by increasing the thickness of the flare portion as compared with the sliding portion, but such processing has been extremely difficult with the conventional technology.

[0005]

The object of the present invention is to provide a poppet valve in which a hollow stem connected to a valve body is provided with a straight tubular sliding portion,
This problem can be solved by forming the flare portion connected to the sliding portion and forming the flare portion thicker than the sliding portion. In this case, it is preferable that the thickness of the flare portion is sequentially increased from the stem side to the end portion.

[0006] As a method for forming a stem, a cup-like shape having a cylindrical wall formed by drawing a metal plate to have a diameter substantially equal to the end diameter of the flared portion and a bottom wall closing one end thereof is provided. The open end of the cylindrical wall is produced by forming a material, plastically working it from the bottom wall side to the open end of the cylindrical wall by a pair of plastic molds composed of punches and dies, and reducing the diameter and simultaneously extending in the axial direction. The problem can be solved by forming a stepped portion composed of several stepped portions, and pressing the stepped portion with a mold to form a flare portion.

[0007]

[Function] The large-diameter end of the flare portion is formed to have a large thickness, and has high mechanical strength to withstand high stress during friction welding or when seated on a valve seat in a state where the combustion chamber receives heat. . The metal plate as a raw material is formed into a cup-shaped semifinished product as a material for a subsequent ironing process by drawing. The cup-shaped semi-finished product comprises a cylindrical wall having one open end and a bottom wall closing the other end of the cylindrical wall.In the handling step, the bottom wall is handled from the open end to reduce the outer diameter. Extends axially. The handling process is carried out over several stages, leaving a slight unhandled end at the handling end. Therefore, the unhandled portion becomes a step-like portion composed of several steps with several steps of processing. Further, the thickness of the stepped portion becomes thinner as it is processed at a later stage. When the handling step is completed, the step-like portion is formed into a smooth curve by pinching, with the wall thickness increasing from the base to the end of the flare portion. Then trim and finish the flare.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
In FIG. 1, reference numeral 10 denotes an example of a poppet valve manufactured by the manufacturing method of the present invention. The poppet valve 10 is a hollow stem 11 formed by pressing a steel plate, which is a kind of metal plate.
And a valve body 12 frictionally welded to one end of the stem 11. In addition, a stainless steel plate titanium plate etc. other than a steel plate are used for a metal plate.

The stem 11 is a valve guide 13 of the engine.
And a flare portion 15 integrally formed at one end of the sliding portion 14. The sliding portion 14 is made of a relatively thin straight tube having a circular cross section, and the flare portion 15 is a portion whose outer diameter is increased from one end of the sliding portion 14 toward the valve element 12. The valve body 12 is welded. W indicated by a virtual line indicates a joining line by welding. In addition, the flare part 15 is the sliding part 1.
While increasing the outer diameter in a quadratic curve from 4 to the end,
The plate thickness is also processed so as to gradually increase.

FIG. 2 shows a disk-shaped material 17 used in this molding method, which is made by stamping a steel plate into a circle. The disk-shaped material 17 is transformed into a second semi-finished product 20 shown in FIG. As shown in FIG. 4, the die used in this step is a die 90 having a shaft hole 90d having substantially the same diameter as the large diameter portion of the flare portion 15, and a die 9 having the same size.
It includes a punch 91 provided with a cylindrical portion 91a that advances and retracts into 0d. Note that 90a is a knockout, and 90b is an extrusion spring.

In this step, when the cylindrical portion 91a of the punch 91 advances into the shaft hole 90d, the disc-shaped material 17 is pushed into the shaft hole 90d from a portion in contact with the cylindrical portion 91a, and A first cylindrical surface 21 having substantially the same diameter as the diameter,
A cup-shaped first semi-finished product 20 having a first bottom surface 22 whose one end is closed is produced. The thickness of the first semi-finished product 20 changes from the original flat circular plate material 17 to a three-dimensional shape, and the thickness of the first semi-finished product 20 becomes slightly thinner as a whole.

Next, the first semi-finished product 20 is transformed into a second semi-finished product 30 shown in FIG. As shown in FIG. 5, the die for handling used in this step includes a die 92 and a punch 93. Dice 9
2 has a shaft hole 92b formed at the entrance. Punch 9
3 also has a shaft portion 93b corresponding to this. The gap between the shaft hole 92b of the die 92 and the outer diameter 93b of the punch 93 is set as an annular space slightly smaller than the plate thickness of the first semi-finished product 20. It is preferable that the diameter ratio between the punch 93 and the punch 91 is 0.75 to 0.82.

In this step, the first semi-finished product 20 is
Into the shaft hole 93b of the die 92. First, the outer periphery of the first cylindrical surface 21 of the first semi-finished product 20 is handled by the shaft hole 92b, and its thickness and diameter are reduced and its axial length is extended. The punch 93 advances in the shaft hole and approaches the end, and the process is completed at the place where the first semi-finished product 20 is sandwiched between the lower end and the bottom of the punch 93, and the second semi-finished product 30 is completed. Therefore, the second semi-finished product 30
Is smaller than the first semi-finished product 20 and the second is thinner and thinner
In addition to having a cylindrical surface 31 and a second bottom surface 32 having a small diameter,
A first stepped portion 33 formed at an open end of the second cylindrical surface 31 by an end of the first cylindrical surface 21 and a horizontal portion connected thereto;
Is formed.

The second semi-finished product 30 is then processed by a die 94 and a punch 95 as shown in FIG.
The third semi-finished product 40 shown in FIG. In other words, the second cylindrical surface 31 is handled to reduce the thickness and the diameter thereof, and at the same time, the third cylindrical surface 41 and the third bottom surface 42 whose axial lengths are increased, in substantially the same manner as the handling process in the previous step. A third with
The semi-finished product 40 is completed. At the open end of the third cylindrical surface 41, a second step 43 is formed by the end of the second cylindrical surface 31 and a horizontal portion connected thereto, following the first step 33.

As shown in FIG. 7, the third semi-finished product 40 is transformed into a fourth semi-finished product 50 in substantially the same manner as the process of transforming the second semi-finished product 30 into the third semi-finished product 40. As shown in FIG. 3D, the fourth semi-finished product 50 has a small-diameter and thin-walled fourth cylindrical surface 51 forming the sliding portion 14 and a fourth bottom surface 52 closing one end thereof. At the other end of the fourth cylindrical surface 51, a fourth step 53 is formed by the end of the fourth cylindrical surface 41 and the horizontal portion connected thereto. The fourth step 53 is formed by the fourth cylindrical surface 5 together with the two steps 33 and 43 made earlier.
The outer diameter increases stepwise from 1 to form a stepped portion 55 whose envelope is conical. If necessary, the semi-finished product is similarly formed and extends to the eleventh semi-finished product, and automatic work is performed by a transfer press.

As shown in FIG. 8A, the stepped portion 55 is formed by a lower die 71 and an upper die 72 in a subsequent finishing step.
The flare portion 15 is formed by a molding die composed of
The flare portion 15 has a stepped portion 55 formed into a substantially umbrella-shaped smooth curve in which the outer diameter increases in a quadratic curve, and the thickness thereof is thicker than the sliding portion 14, From the end to the end. However, this shape is not indispensable, and as shown in FIG.
It is also possible to form it. Here, the handling mold is described, but a drawing mold may be used, and generally, the entire plastic working mold can be used.

[0017]

According to the poppet valve of the present invention,
Since the flare portion of the stem is made thicker than the sliding portion, the stem can have a rigidity required for friction welding or without damaging the valve element and the valve seat, and can be made lightweight.
According to the poppet valve manufacturing method of the present invention, a large-diameter and thick-plated portion forming a flare portion can be formed in the step of forming the sliding portion by drawing, thereby simplifying the manufacturing process. And so on.

[Brief description of the drawings]

FIG. 1 is a sectional view of a poppet valve showing one embodiment of the present invention.

FIG. 2 shows a disc-shaped material, (a) is a side view,
(B) is a front view.

FIG. 3 is a process diagram showing a deformed state of a stem material.

FIG. 4 is a cross-sectional view of a mold showing a processing step of a first semi-finished product.

FIG. 5 is a sectional view of a mold showing a processing step of a second semi-finished product.

FIG. 6 is a cross-sectional view of a mold showing a processing step of a third semi-finished product.

FIG. 7 is a sectional view of a mold showing a processing step of a fourth semi-finished product.

FIG. 8 is an enlarged sectional view showing a main part of a mold in a processing step of a flare portion.

[Explanation of symbols]

 10 poppet valve 11 stem 12 valve element 13 valve guide 14 sliding part 15 flare part 16 seat surface 17 ····· Disc shaped material 20 ···· First semi-finished product 21 ···· First cylindrical surface 22 ····· First bottom surface 30 ····· Second semi-finished product 31 ······· Second cylindrical surface 32 second bottom surface 33 step portion 40 third semi-finished product 41 third cylindrical surface 42 third bottom surface 43 step portion 50 ..The fourth semi-finished product 51 ... the fourth cylindrical surface 52 ... the fourth bottom surface 53..the step portion 55..the step portion 71..the lower mold 72..the lower part Die 90 ... Die 90a ... Knockout 90b ... Extrusion spring 90d ... Shaft hole 91 ... Punch 91a ... Cylinder 92 ... Chair 92, 94, 96 .... dice 92b ··· shaft hole 93 .... punch 93b ··· shaft portions 95, 97 ... punch W ···· joint line

Claims (3)

[Claims] A hollow stem connected to a valve body is composed of a straight tubular sliding portion and a flare portion connected to the sliding portion, and the thickness of the flare portion is smaller than the thickness of the sliding portion. A poppet valve formed into a thick wall. 2. The poppet valve according to claim 1, wherein the flare portion is formed such that the thickness of the flare portion is gradually increased from the stem toward the end. 3. A cup-shaped material having a cylindrical wall formed to have substantially the same diameter as the end diameter of the flare portion and a bottom wall closing one end thereof is formed by drawing a metal plate. Steps consisting of several steps at the open end of the cylindrical wall by plastically working from the bottom wall side to the open end of the cylindrical wall by a pair of plastic molds consisting of A press forming method for a poppet valve, comprising a step of forming a flared portion and forming a flared portion by pressing the stepped portion with a mold.