JP3469275B2 - Method and apparatus for manufacturing gear base material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear blank as a material for forming a speed change gear used in a synchromesh type transmission, a method for manufacturing the gear blank, and an apparatus therefor. .

[0002]

2. Description of the Related Art A speed change gear used in a synchromesh type transmission has a speed change tooth portion and a boss portion having a diameter smaller than that of the speed change tooth portion, and a chamfer is provided at the tip of the outer periphery of the boss portion. The reverse taper-shaped spline teeth are formed at equal intervals in the circumferential direction of the boss.

In forming the above-mentioned speed change gear, a method of manufacturing by cutting, a speed change tooth portion and a spline tooth portion are individually formed by machining or cold forging, and both parts are fitted to each other. Conventionally, a method of integrating by welding is known.

By the way, in the method of manufacturing by cutting, it is necessary to provide a relief for the blade at the root of the spline tooth, so that the effective length of the spline tooth is shortened, and due to cutting, the fiber flow However, there is a problem in that the gear for speed change having a high mechanical strength cannot be obtained.

On the other hand, in the method in which both parts are individually formed and fitted together, machining and welding processes are required, resulting in high manufacturing cost, and the fibers of the speed change tooth part and the spline tooth part are increased. Since the flow is discontinuous, in this case also, there is a problem that it is not possible to obtain a speed change gear having high mechanical strength.

In order to solve such a problem, Japanese Patent Publication No. 2542300 proposes a speed change gear in which a speed change tooth portion and a spline tooth portion are integrally formed by forging.

In the above speed change gear, straight spline teeth are formed on the outer periphery of the boss portion by forging, and dies radially arranged between the spline teeth are forcibly pushed in to form the reverse tapered spline teeth by plastic deformation. Since it is formed, it is possible to obtain a reverse taper-shaped spline tooth with a long effective length, and since the fiber flow is not cut, it is possible to obtain a speed change gear with high mechanical strength. have.

[0008]

By the way, in the gear for speed change described in the above publication, when forming the gear blank, a gear blank is set on the lower die and the gear blank is pressed by the lower die moving downward. While moving downward, a large number of radially arranged dies provided on the outer periphery of the gear blank are moved inward in the radial direction, and each die is pushed between the straight spline teeth formed on the outer periphery of the boss portion of the gear blank, Since the reverse taper-shaped spline teeth are formed by the pushing, the following inconveniences occur.

That is, the gear blank pushed down by the pressing of the upper die and the die moving inward in the radial direction are
Because of the relative movement in the axial direction, the material escapes toward the root of the straight spline tooth during the plastic working of the gear blank, and the escape of the material causes a step at the root of the inverse tapered spline tooth, resulting in a boss portion. It is not possible to form an inverted taper spline tooth completely up to the root.

Further, since the inclined pin provided inside the lower portion of the cam, so-called finger pin, is inserted into the pin hole formed in the die, and the die is moved inward when the cam descends, Since it is not possible to use a highly rigid finger pin and a molding pressure acts on the finger pin at the time of molding, the finger pin is easily damaged and there is a problem in durability of the manufacturing apparatus.

An object of the present invention is to provide a gear base material having excellent mechanical strength, which has a reverse tapered spline tooth having a long effective length reaching the root of the boss portion, a method for manufacturing the gear base material, and an apparatus therefor. Is to provide.

[0012]

In order to solve the above-mentioned problems, in the gear blank according to the present invention, a circular tooth forming portion formed by forging and one side surface of the tooth forming portion are roots. A small diameter boss portion and an inverse taper spline tooth that extends axially from the root of the boss portion along the outer circumference of the boss portion and chamfers are formed on both sides of the tip portion. However, between the straight spline teeth formed to the root of the boss portion by forging, the die radially arranged with the boss portion as the center is lowered together with the gear blank in which the straight spline teeth are formed of the tooth forming portion. The structure is adopted in which the tooth forming portion is formed so as to reach one side surface by being forcedly slid inward along one side surface and being pushed inward.

As described above, the radially arranged dies are lowered together with the gear blank and are forcedly slid inward along one side surface of the tooth forming portion to be pushed between the straight spline teeth, whereby The gear blank and the gear blank do not move relative to each other in the axial direction, preventing the material from plastically flowing to the root of the straight spline tooth during plastic working by pushing the die, and the effective length reaching one side of the tooth forming part. It is possible to obtain long inverse tapered spline teeth. Further, since the inverse tapered spline teeth are formed by plastic working, the fiber flow is not cut, and a gear blank having excellent mechanical strength can be formed.

The gear blank is made into a product by forming gear teeth in the tooth forming portion.

In the method for manufacturing a gear blank according to the present invention, a disk-shaped tooth forming portion, a small-diameter boss portion having one side surface of the tooth forming portion as a root, and a shaft from the root of the boss portion. Direction, and forming a gear blank having straight spline teeth with chamfers formed on both sides of the tip by forging, and supporting the lower surface of the tooth forming portion of the gear blank by a large number of dies arranged radially. Then, while pushing down the die together with the gear blank, the die is forced to slide inward along one side surface of the tooth forming portion and pushed between the straight spline teeth to reach the one side surface of the tooth forming portion. That is, a structure including a step of forming a reverse tapered spline tooth is adopted.

Further, in the gear blank manufacturing apparatus according to the present invention, it comprises a fixed lower die and an upper die which can be moved up and down with respect to the lower die. The lower die has two different diameters. The die holders are provided concentrically inside and outside, and between the outer die holder and the inner die holder, a molding part for molding the inverse tapered spline teeth is radially arranged with a large number of dies formed on the inner upper side. At least one of the circumference and the outer circumference of the inner die holder is provided with a guide groove for guiding the up-and-down movement of the die, and the other end is provided with a taper surface having a smaller diameter toward the lower end, and the end surface of the guide groove is in the same direction as the taper surface. The inclined taper surface is formed, and the inner and outer surfaces of each die are formed so as to be in contact with and guided by each taper, and the lower end of each die is supported by a knockout plate that is supported so that it can move up and down. Presses upward the knockout plate by an elastic member, wherein the upper mold is to that adopted the configuration in which a push ring depress multiple dies simultaneously during lifting.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a gear blank A according to the present invention. The gear blank A has a disc-shaped tooth forming portion 1 and a boss portion 2 having a diameter smaller than that of the tooth forming portion 1. The boss portion 2 has one side surface of the tooth forming portion 1 as a root.

On the outer periphery of the boss portion 2, spline teeth 3 having an inverse taper shape whose width dimension becomes smaller toward the upper portion are formed at equal intervals. Each spline tooth 3 extends in the axial direction from the root of the boss portion 2, and chamfers 4 are provided on both sides of the tip portion.

1 to 4 show the gear blank A shown in FIG.
The manufacturing method of is shown in stages. Figure 1 shows a cylindrical billet 1.
Indicates 0. The billet 10 is hot-installed in the first installation process. FIG. 2 shows a blank forming blank 11 formed by upsetting. This material 1
1 has a disk-shaped portion 12 having a rounded outer periphery, and tapered projections 13 and 14 are formed above and below the disk portion 12.

The material 11 is roughly formed in the second forming step to form the first gear blank 15 shown in FIG.
The first gear blank 15 is provided above and below the tooth forming portion 16,
Boss portions 17 and 18 having the side surface of the tooth forming portion 16 as a root
Is formed, and a large-diameter spline forming portion 19 is provided at the base of the lower boss portion 18. In addition, the upper boss portion 17
Is formed with a bottomed hole 20 that opens on the upper surface. Next, the first gear blank 15 is molded in the third molding step to mold the tooth forming portion 16 and the upper boss portion 17 into a predetermined shape.
The bottom of the is punched out. In addition, spline teeth are formed in the spline forming portion 19. The forming is performed cold.

FIG. 4 shows a second gear blank 21 having spline teeth formed therein. The outer periphery of the lower boss portion 18 extends axially from the root of the boss portion 18 along the outer periphery of the boss portion 18. The straight spline teeth 22 are formed at equal intervals in the circumferential direction, and chamfers 23 are provided on both sides of the tip of each straight spline tooth 22.

The gear blank 21 is subjected to heat treatment such as normalization and annealing, if necessary, and the surface scale is removed by shot blasting.

As shown in FIG. 5, the second gear blank 21 is formed with the inverse tapered spline teeth 3 in the fourth molding step. The forming is performed cold. Further, the manufacturing apparatus shown in FIGS. 6 and 7 is used for molding.

The manufacturing apparatus comprises a fixed lower die 30 and an upper die 31 which is moved up and down with respect to the lower die 30.

The lower die 30 has a fixed plate 32, and a holder support member 33 supported by the fixed plate 32 has a stepped hole 34 formed therein. Two die holders 35 and 36 having different diameters are incorporated in the stepped hole 34.

The outer die holder 35 has a ring shape, and a step 35a provided on the outer circumference is supported by a step portion 34a formed on the inner circumference of the stepped hole 34. A taper surface 37 is formed on the inner circumference of the die holder 35 so as to have a smaller diameter toward the lower end.

The inner die holder 36 is fixed by bolts 38 screwed into the fixed plate 32, and the outer die holder 3 is fixed.
5 are arranged concentrically. A large diameter portion 39 is formed in a portion of the inner die holder 36 located inside the outer die holder 35, and a large number of guide grooves 40 are formed on the outer periphery of the large diameter portion 39 at equal intervals in the circumferential direction. The end surface of each guide groove 40 is a tapered surface 41, and the tapered surface 41 is inclined in the same direction with respect to the tapered surface 37 of the outer die holder 35 with the same gradient.

Outer die holder 35 and inner die holder 36
Between the large-diameter portions 39, the same number of dies 42 as the guide grooves 40 are installed in a radial arrangement so that the inner portions fit into the guide grooves 40. The entire outer periphery of each die 42 is a tapered surface 43 which is guided by a tapered surface 37 formed on the outer die holder 35, and the inner surface is a tapered surface 41 of the guide groove 40 formed on the inner die holder 36.
A tapered surface 44 is provided which is guided by the contact. A tapered molding portion 45 is formed on the inner tapered surface 44.

A large number of dies 42 are provided in a knock-out plate 46 incorporated in the stepped hole 34 of the holder supporting member 33.
The lower end is supported by. The knockout plate 46 is supported so that it can be raised and lowered, and is pressed upward by the elastic member 47 to be pressed against the lower surface of the outer die holder 35.

The upper die 31 has a ring-shaped punch holder 48, and a punch 49 and an elastic member 50 for pressing the punch 49 downward are incorporated in the punch holder 48. Further, the punch holder 48 has an upper die 31
A push ring 51 that presses a large number of dies 42 at the same time is mounted.

The manufacturing apparatus has the above-mentioned structure, and when forming the inverse tapered spline teeth 3, the lower part of the second gear blank 21 is inserted between a large number of dies 42 arranged radially, and the second gear blank is inserted. The upper die 31 is lowered in a state where the lower surface of the tooth forming portion 1 of 21 is supported by the multiple dies 42.

When the upper die 31 descends, the punch 49 provided on the upper die 31 contacts the upper surface of the second gear blank 21 to press the second gear blank 21, and the punch 49 is held in a stopped state. On the other hand, the push ring 51 descends,
A large number of dies 42 are pushed down by the push ring 51 and descend.

When the die 42 descends, the second gear blank 21
And the die 42 moves to the outer die holder 3 simultaneously.
5 descends along the tapered surface 37. For this reason, each die 42 moves inward along the lower surface of the tooth forming portion 1 of the second gear blank 21 while the molding portion 45 is pushed between the straight spline teeth 22 of the second gear blank 21. By pushing in the forming portion 45, as shown in FIG. 1, the inverse tapered spline tooth 3 is formed.

As described above, when the reverse tapered spline teeth 3 are formed, the many dies 42 move inward while descending together with the second gear blank 21, and the forming portions 45 provided on the respective dies 42 are moved to the first position. Since the second gear blank 21 moves inward along the lower surface of the tooth forming portion 1, the material of the second gear blank 21 flows toward the roots of the spline teeth 22 during the plastic working by pushing the forming portion 45. Very few.

Therefore, as shown in FIG. 1, the tooth forming portion 1
It is possible to form the inverse tapered spline tooth 3 having a long effective length up to the lower surface of the.

When the upper die 31 is lifted after the reverse tapered spline teeth 3 are molded, the knockout plate 46 pushed down by the die 42 at the time of molding moves upward by the pressing of the elastic member 47, and the knockout plate 4 is pushed.
6, the die 42 is pushed up. At this time, since the dies 42 are guided by the tapered surfaces 41 formed in the guide grooves 40 of the inner die holder 36, the dies 42 move upward while moving upward, and the outward movement causes the forming portion 45 to reverse. It is pulled out from the tapered spline tooth 3. Therefore, the gear blank A having the inverse tapered spline teeth 3 formed thereon can be removed upward from between the many dies 42.

Although the guide groove 40 is formed in the inner die holder 31 in the manufacturing apparatus shown in FIG. 6, the guide groove may be formed in the inner surface of the outer die holder 30. in this case,
The outer circumference of the inner die holder 31 is tapered.

[0038]

Further, since the inverse tapered spline teeth are formed by plastic deformation, the fiber flow is not cut, and it is possible to obtain the inverse tapered spline teeth which are strong in strength.

Further, since the taper surface of the outer die holder slides and guides the taper surface provided on the outer side of the die, when forming the inverse tapered spline teeth, the molding pressure is applied by the contact portion between the outer die holder and the die. It is possible to obtain a manufacturing apparatus that can be received and has excellent durability.

[Brief description of drawings]

FIG. 1 is a perspective view of a billet used for molding a gear blank according to the present invention.

FIG. 2 is a perspective view showing a rough forming material obtained by upsetting the billet shown in FIG.

FIG. 3 is a perspective view showing a first gear blank obtained by rough forming of the rough formed blank shown in FIG.

4 is a perspective view showing a second gear blank obtained by molding the first gear blank shown in FIG.

5 is a perspective view showing a gear blank obtained by molding the second gear blank shown in FIG.

FIG. 6 is a vertical sectional front view showing a manufacturing apparatus according to the present invention.

FIG. 7 is a plan view of the lower mold of FIG.

FIG. 8 is a vertical sectional front view showing a molded state of a gear blank.

[Explanation of symbols]

1 Tooth formation part 2 Boss 3 Reverse tapered spline teeth 4 Chamfa 22 straight spline teeth 30 Lower mold 31 Upper mold 35 Outside die holder 36 Inner die holder 37 Tapered surface 40 guide groove 41 Tapered surface 42 die 43 Tapered surface 44 Tapered surface 45 Molding part 51 push ring

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B29D 15/00 B29D 15/00 (56) References JP-A-63-120958 (JP, A) JP-A-2-133141 (JP , A) JP-A-52-61162 (JP, A) JP-A-4-231140 (JP, A) Actually open flat 2-16246 (JP, U) JP-B-49-11543 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 55/08 B21J 5/02 B21J 5/08 B21J 5/12 B21K 1/30 B29D 15/00

Claims (2)

(57) [Claims] 1. A disk-shaped tooth forming portion, a small-diameter boss portion having one side surface of the tooth forming portion as a root, and a chamfer extending axially from the root of the boss portion and on both sides of a tip portion. A step of forming a gear blank having a straight spline tooth formed by forging, a fixed lower die, and an upper die capable of moving up and down with respect to the lower die.
The two die holders with different diameters are
Are installed concentrically and face the lower edge on the inner circumference of the outer die holder.
To form a taper surface with a small diameter,
A guide groove for guiding the up and down movement of the die is provided on the
The end surface of the groove is a taper surface that is inclined in the same direction as the taper surface.
Between the outer die holder and the inner die holder, a forming part for forming the inverse tapered spline teeth is formed on the inner upper side, and the inner surface and the outer surface of each die are in contact with the above taper.
Radial multiple dies with tapered surfaces that are guided by touch
Place and push down many die at the same time on the upper die.
Using a molding tool that has a shring,
The lower part of the gear blank is inserted, the lower surface of the tooth forming portion of the gear blank is supported by a large number of dies arranged radially, and the upper die is lowered to push down the die together with the gear blank to form the tooth forming portion. Forming an inverted taper-shaped spline tooth to a position reaching one side surface of the tooth forming portion by forcibly sliding inward along one side surface and pushing it between the straight spline teeth. Manufacturing method of gear blank. 2. A disk-shaped tooth forming portion, a small-diameter boss portion having one side surface of the tooth forming portion as a root, a shaft extending axially from the base of the boss portion, and chamfers formed at both ends of the tip portion. Using a gear blank formed by forging that has a straight spline tooth formed by pushing the die between the straight spline teeth of the gear blank, a reverse taper spline tooth is formed to a position reaching one side surface of the tooth forming portion. In a manufacturing device for a gear blank to be formed, a fixed lower die and an upper die capable of moving up and down with respect to the lower die are provided, and two die holders having different diameters are concentrically provided inside and outside the lower die. Between the outer die holder and the inner die holder, a plurality of dies having a forming part for forming the inverse tapered spline teeth formed on the inner upper side are arranged radially, and the die is formed on the outer periphery of the inner die holder. A guide groove for guiding the up-and-down movement is provided, a tapered surface having a smaller diameter toward the lower end is formed on the inner periphery of the outer die holder, and the end surface of the guide groove is a tapered surface inclined in the same direction as the tapered surface, and The inner and outer surfaces of each die are formed with tapered surfaces that are contacted and guided by the above tapers, and the lower end of each die is supported by a knockout plate that is supported so that it can move up and down, and the knockout plate is pressed upward by an elastic member. The upper die is provided with a push ring that pushes down a large number of dies at the same time when descending .