JP2904702B2 - Gear Forging Die and Gear Forging Method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging die for forming a gear forging product having a lower die having a tooth profile and an upper die punch and having a tooth profile formed on an outer peripheral portion, and the forging die. Forging method for forming a gear forged molded product using a mold,
In particular, the present invention relates to a gear forging die and a gear forging method capable of reducing a thinned portion generated on an outer peripheral portion of a gear forged product.

[0002]

2. Description of the Related Art Generally, in order to form a gear forged product by a forging die, a forged material is set in a molding concave portion of a lower die having a tooth profile portion formed on an inner peripheral portion, and then the outer peripheral portion is set. The upper die punch having a tooth profile formed therein is inserted into the molding recess of the lower die in an in-fit manner, and the forging material in the molding recess is pressed, and this forging material is moved outward, that is, toward the tooth profile. By flowing, a tooth profile is formed on the outer peripheral portion of the forged material via the tooth profile of the lower die and the tooth profile of the upper punch. In the conventional forging die, the bottom surface of the molding concave portion of the lower die and the lower end surface of the upper die punch are formed in a flat shape, and the forging material is pressed between these flat surfaces to perform forging. .
In addition, the conventional forging material had a columnar shape with upper and lower surfaces formed as flat surfaces.

[0003]

When the conventional forging material is pressed between the flat bottom surface of the forming concave portion of the lower die and the flat lower end surface of the upper die punch, the forging material is obtained. Flows toward the outside in the horizontal direction to form a tooth profile portion on the outer periphery thereof, so that the forged material is formed on the outer periphery of the bottom surface of the molding concave portion of the lower die and the outer periphery of the lower end surface of the upper die punch. Since it does not flow sufficiently to the end portion, as shown in FIG.
Large underfill portions 104 and 105 were formed at the upper and lower edges of the outer peripheral ends of the upper and lower surfaces 102 and 103, respectively.

[0004] For this purpose, in order to make the gear forged product 100 into a gear product, at a cutting station, the gear forged product 100 shown in FIG.
In addition, the portions 102a and 103a indicated by phantom lines must be cut, and the cut amount is large, the material yield is poor,
There was a problem that the material cost was high. In addition, since the amount of cutting is large, there is a problem that the cutting time is long and the cutting cost is high.

In addition, since the forging material is pressed between the planar bottom surface of the molding concave portion of the lower die and the planar lower end surface of the upper punch, the forging is performed between the upper and lower planes. For this reason, there is a problem that the forging load is large and the life of the mold is shortened. It is an object of the present invention to reduce the amount of cutting by reducing the underfill portion generated at the outer peripheral end of the tooth profile, improve the material yield, reduce the material cost, and reduce the cutting time to reduce the processing cost. An object of the present invention is to provide a gear forging die and a gear forging method capable of improving the life of the die.

[0006]

A forging die for a gear forged product according to claim 1, wherein a lower die having a toothed portion formed on an inner peripheral portion of a molding concave portion, and a toothed portion formed on an outer peripheral portion, An upper die punch inserted into the lower die in an in-fit manner from above,
In a forging die for molding a gear forged product having a tooth profile formed on an outer peripheral portion, an outer peripheral portion of a lower end surface of the upper die punch is formed with an annular tapered surface that is gently inclined so as to become higher toward the outside . The lower end of the upper punch
The inside becomes higher as it goes inside the annular tapered surface.
With a conical tapered surface that is gently inclined
is there.

According to a second aspect of the present invention, there is provided a method for forging a gear, comprising: a lower die having a toothed portion formed on an inner peripheral portion of a molding concave portion; and a toothed portion being formed on an outer peripheral portion. In a forging method of forming a gear forged product having a tooth profile portion formed on an outer peripheral portion by using a forging die having an upper die punch inserted in a shape, an outer peripheral side portion of a lower end surface of the upper die punch is formed. An annular tapered surface that is gently inclined so as to be higher toward the outside is formed in advance , and the lower end surface of the upper die punch is
It will be higher inside the part inside the annular taper surface.
A conical taper surface that is gently inclined is formed in advance , and during forging, through the annular taper surface, the flow of the forged material to the outer peripheral portion is promoted , and the conical taper is formed.
Through the face, at least the central part of the upper end face of the forged material
While maintaining a free surface not in contact with the upper die punch
It is characterized by doing.

A method is also known in which an annular thick portion is formed in advance on the outer peripheral portion of the upper surface of the forged material, and forging is performed using the forged material.
Desirable (claim 3 dependent on claim 2 ) . In addition, a method of forming a circular shallow concave portion in advance in a portion other than the outer peripheral side portion of the bottom of the forged material and forging using the forged material is also available.
Desirable (claim 4 dependent on claim 3).

[0009]

In the forging die for a gear forged product according to the first aspect, after setting the forging material into the molding recess of the lower die, the upper die punch is fitted into the lower die from above. When the forged material is inserted into the forged material, the forged material is pressed and flows to the outside of the outer peripheral portion, and the tooth profile is formed on the outer peripheral portion side of the forged material via the tooth profile of the lower die and the tooth profile of the upper die punch. At this time, the annular taper surface which is formed in advance on the outer peripheral portion of the lower end surface of the upper die punch and which is gradually inclined so as to become higher toward the outside promotes the flow of the forged material to the outer peripheral portion.
That is, since the working force acts on the forged material obliquely downward and outward due to the inclination of the annular tapered surface, the forged material flows strongly to the outer periphery.

As described above, the flow of the forged material to the toothed portion of the lower die and the toothed portion of the upper die is promoted, and the forging material is sufficiently filled. It is molded firmly, with almost no underfill. In particular, the annular tapered surface forms an acute angle at the outer peripheral end of the upper surface of the tooth profile of the forged gear forged product, so that there is no underfill.

As described above, the underfill portion generated in the tooth profile portion of the gear forged product can be reduced, so that the amount of cutting at the time of cutting can be reduced, the cutting time can be shortened, and the cutting cost can be reduced. . In addition, since the amount of cutting can be reduced, the material yield can be improved, and the material cost can be reduced. In addition, since the flow of the forged material to the outer peripheral portion is promoted, the forging processing force is reduced, the life of the forging die can be improved, and the material is sufficiently filled, so that the tooth profile of the gear forged product is formed. The quality is also excellent.

[0012] At the time of forging, at least the forging material is formed through a conical tapered surface formed on the lower end surface of the upper die punch inside the annular tapered surface and gently inclined so as to become higher toward the inner side. Since the center part is formed while maintaining a free surface that does not come into contact with the upper die punch, it is possible to secure a place for the forging material to escape to this part, reduce the forging processing force, and improve the life of the forging die. it can.

In the method for forging a gear forged product according to the second aspect, basically the same operation and effect as those of the forging die for a gear according to the first aspect are obtained . In 請 Motomeko 3 forging methods gear forgings, since the thick portion of the annular is previously formed on the outer peripheral portion of the upper surface of the forging material, at the time of forging using a forging material of the annular The thick part is strongly pushed by the annular taper surface of the upper die punch, and its flow is more strongly promoted and filled into the tooth shape part of the lower die and the tooth shape part of the upper die in the outer peripheral part, and the gear forging is performed. The tooth profile of the molded article is firmly formed without any underfill. Therefore, the underfill portion generated in the tooth profile of the gear forged product can be reduced, and the material yield can be improved. Others as in claim 2
The operation and effect of

In the method for forging a gear according to the fourth aspect , since the shallow recess is formed in a portion other than the outer peripheral side portion of the bottom of the forged material in advance, when this shallow recess is filled during forging, The action of flowing the outer peripheral side portion of the forged material to the outside works. Thereby, the flow of the outer peripheral side portion of the forged material to the tooth profile of the lower die and the tooth profile of the upper punch is promoted, and the tooth profile of the gear forged product is accurately formed. Therefore, it is possible to reduce the underfill portion occurring toothing of the gear forgings, wear material yield in countercurrent above. Other claim 3
The same operation and effect as described above can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A forging die for a gear forged product and a method for forging a gear according to the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a lower die 20 of a forging die 11 of a forging apparatus 10 for forging a gear forged product 1 (see FIG. 4) has a forming recess 21 at a center portion, and this forming is performed. Die 23 in which tooth profile 22 is formed on the outer periphery of recess 21
And a lower die punch 25 whose upper surface is positioned at the same height as the bottom surface of the molding recess 21 and the lower die 23 is fixed to the lower set plate 26. The lower set plate 26 is fixed to the base member 12 of the forging device 11.

The upper die 30 of the forging die 11 of the forging device 10
The upper die 32 is disposed at the center of the upper die 30 of the forging die 10 so as to face the molding concave portion 21 of the lower die 23, and the upper die 32 has a tooth profile 31 formed on the outer periphery thereof. The punch 32 comprises a punch holder 34 for fixing the punch 32 to an upper set plate 33. The upper set plate 33 is fixed to the ram member 13 of the forging device 10.

An annular taper surface 35 is formed on the outer peripheral portion of the lower end surface of the upper die punch 32 so as to be gently inclined so as to become higher toward the outside. A conically tapered surface 36 that is gently inclined is formed. The annular tapered surface 3
5 is formed at an inclination angle of about 10 ° from a horizontal plane perpendicular to the axis of the upper die punch 32 in this embodiment. FIG.
As shown in the figure, the forging material 2 forged by the forging apparatus 10 has an annular thick portion 3 formed in advance on the outer peripheral portion of the upper surface, and a shallow circular shape is formed on a portion other than the outer peripheral portion of the bottom. The recess 4 is formed in advance.

Next, the forging apparatus 1 configured as described above
A forging method for forging the gear forged product 1 using 0 will be described. As shown in FIG. 1, the lower die 2 of the forging die 11
In a state where the forging material 2 is set in the forming concave portion 21 of the lower die 23, the ram member 13 is lowered, and the upper punch 32 is lowered via the upper set plate 33 and the punch holder 34. Then, as shown in FIG. 2, the lower end of the upper die punch 32 is
The forged material 2 set in the forming recess 21 of the lower die 23 by the upper die punch 32
Is pressed to form a gear forging product in which the tooth profile 5 is formed on the outer side via the tooth profile 22 on the inner periphery of the molding recess 21 of the lower die 23 and the tooth profile 31 on the outer periphery of the upper die 32. 1 is obtained.

At the time of this forging, the upper punch 32
Since the annular tapered surface 35 of the outer peripheral side of the forging material 2 causes a downwardly directed processing force and a downwardly diagonally outwardly directed processing force to act, the forged material 2 has a tooth profile 22 of the lower die 23 and a tooth profile of the upper die 32. The flow to the portion 31 is promoted, the forging material 2 is sufficiently filled, and the tooth profile 5 of the gear forging 1 is accurately and firmly formed. In particular, since the processing force acts on the forged material 2 obliquely downward and outward due to the inclination of the annular tapered surface 35, the forged material 2 flows strongly to the outer periphery . The forging material 2, the annular thick portion 3 on the outer peripheral portion of the upper surface are formed in advance, it is thick portion 3 of the annular,
The toothed portion 22 of the lower die 23 and the toothed portion 31 of the upper punch 32 are strongly pressed by the annular tapered surface 35 of the upper die punch 32.
Filling is promoted, and the tooth profile portion 5 of the gear forged product 1 has no underfill.
It is accurately firmly formed on the teeth.

In addition, since the circular recess 4 is previously formed in the bottom of the forging material 2, when the recess 4 is filled with the forging material 2 at the time of forging, the outer peripheral side of the forging material 2 is formed. In order to promote the flow to the outside of the portion, the outer peripheral portion of the forging material 2 is strongly flown to the tooth profile 22 of the lower die 23 and the tooth profile 31 of the upper punch 32, and the tooth profile of the gear forging 1 is formed. 5 is formed exactly. In particular, since the outer peripheral end 7 on the upper surface of the tooth profile 5 of the forged gear forged product 1 is formed at an acute angle by the annular tapered surface 35,
No underfill occurs (see FIG. 4). Further, the underfill portion 6 generated at the lower outer peripheral end portion of the tooth profile portion 5 of the gear forged molded product 1 can be extremely reduced (see FIG. 4).

In the gear forged product 1 formed as described above, the portions 9a and 9b indicated by phantom lines in FIG. 4 are portions to be removed by cutting, and the cutting amount is smaller than that of the conventional one. It is extremely low. As described above, since the underfill portion 6 generated in the tooth profile portion 5 of the gear forged product 1 can be reduced, the amount of cutting at the time of cutting can be reduced, and the cutting time can be reduced. Cost can be reduced. Since the cutting amount is small, the material yield can be improved, and the material cost can be reduced. In addition, since the flow of the forging material 2 to the outside of the outer peripheral portion is promoted, forging processing force can be reduced, and the life of the forging die 11 can be improved.

Further, a conical tapered surface 36 which is formed at a portion of the lower end surface of the upper die punch 32 inside the annular tapered surface 35 and is inclined so as to become higher toward the inside,
At the time of forging, forging is performed at least at the center of the upper surface of the forging material 2 while maintaining the free surface 8 not in contact with the upper die punch 32, so that a relief area for the forging material 2 can be secured to this portion, and the forging load is reduced. Thus, the life of the forging die 11 can be improved.

In this embodiment, the upper punch 32 in which a conical tapered surface 36 is formed in a portion inside the annular tapered surface 35 so as to be continuous with the annular tapered surface 35 has been illustrated and described. The present invention is not limited to this, and a horizontal plane may be provided between the annular tapered surface 35 and the conical tapered surface 36 as necessary.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a forging die and a forging material of a forging device according to an embodiment.

2 is a longitudinal sectional view of the forged Zokin type and forging material of FIG. 1 (molded halfway state).

FIG. 3 is a longitudinal sectional view of a forging material used in the embodiment.

4 is a longitudinal sectional view of a forming shape by gear forging at forging Zokin type.

FIG. 5 is a longitudinal sectional view of a gear forged product according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 gear forged product 2 forged material 3 thick portion 4 concave portion 5 toothed portion 8 free surface 11 forging die 21 molding concave portion 22 toothed portion 23 lower die 31 toothed portion 32 upper die punch 35 annular tapered surface 36 conical tapered surface

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Mikio Tomita 1844, Iida, Hachihonmatsu-cho, Higashihiroshima-shi, Hiroshima Pref. Inside the Otodo Works, Hachihonmatsu Plant (72) Kazuya Ito 1844, Iida, Hachihonmatsu-cho, Higashihiroshima-shi, Hiroshima Pref. Oto Works, Yatsuhonmatsu Plant (56) References JP-A-5-138284 (JP, A) JP-A 5-76640 (JP, U) JP-A 4-75634 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) B21K 1/00-31/00 B21J 1/00-13/14 B21J 17/00-19/04

Claims (4)

(57) [Claims] 1. A lower die having a toothed portion formed on an inner peripheral portion of a molding concave portion, and an upper die punch having a toothed portion formed on an outer peripheral portion thereof and being inserted into the lower die from above. With
In a forging die for molding a gear forged molded product having a tooth profile portion formed on an outer peripheral portion, an annular tapered surface that is gently inclined so as to become higher toward the outside is formed on an outer peripheral portion of a lower end surface of the upper die punch.
The annular tapered surface of the lower end surface of the upper die punch
Slowly incline in the inner part so that the inner part is higher
A forging die for a gear forged product, characterized in that a conical tapered surface is formed . 2. A lower die having a tooth profile formed on an inner peripheral portion of a molding concave portion, and an upper die punch having a tooth profile formed on an outer peripheral portion and being inserted into the lower die from above. using forging die with bets, in forging method for forming the formed gear forged product of the gear portion on the outer periphery, on the outer peripheral portion of the lower end surface of the upper mold punch, so as to be higher as the outside loosely When the inclined annular taper surface is formed in advance
In both cases, the annular taper of the lower end face of the upper die punch
-Gently tilt the inside of the surface so that it is higher
Preformed conical tapered surface obliquely, at the time of forging, through the annular tapered surface, as well as facilitating the flow of the outer peripheral portion of the forging material, the conical tape
Through the par surface, at least the center of the upper end surface of the forged material
While maintaining a free surface that does not contact the upper punch.
A forging method for a gear forged product characterized by being shaped . 3. The gear forging method according to claim 2 , wherein an annular thick portion is formed in advance on an outer peripheral portion of an upper surface of the forged material, and forging is performed using the forged material. 4. The gear forged product according to claim 3 , wherein a circular shallow concave portion is previously formed in a portion other than the outer peripheral portion of the bottom of the forged material, and the forged material is forged. Forging method.