JPH0729173B2 - Multi-stage gear forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention is characterized in that a large diameter portion and a small diameter portion are formed coaxially adjacent to each other by plastic working, and a tooth profile is formed on the peripheral surface of the large diameter portion and the small diameter portion. The present invention relates to a method of forming a gear having a multi-step tooth profile.

(B) Conventional technology Conventionally, in order to form a gear using plastic working, as shown in FIG. 7, a disk-shaped metal material 2 ′ is inserted into a forming concave portion 4 having a forming die 5 for forming a tooth form on the periphery. Is pressed by the punch 3 to plastically deform it into a desired shape, and the disk-shaped metal material 2 ′ may be larger or smaller than the reference pitch circle of the forming tooth for forming the tooth profile in the forming recess 4.

In this case, if the diameter of the material is larger than the reference pitch circle of the forming tooth mold for tooth profile formation, the excess thickness is extruded in the direction opposite to the extruding direction (backward extruding) due to the drawing action of the surrounding tooth profile. However, if the diameter of the material is small, on the other hand, the tooth tip shape of the tooth profile will be incomplete due to the peculiar upsetting that both ends in the pushing direction have poorer radial extension than the middle part. If the pushing force is increased to increase the overhang, the mold may be damaged.

Reference pitch circle (PCD) of forming tooth mold for forming tooth profile
Although the above drawbacks can be solved to a certain extent if
Gears with large tooth width and tooth height are liable to have an imperfect tooth profile.

As described above, since there is a limit to the load on the mold and the improvement of the bulging force in the radial direction at both ends in the pushing direction, a gear having a large tooth width and tooth height was formed using the plastic deformation technique. In this case, the end portion of the tooth profile in the tooth width direction has an imperfect shape, and the solution of the problem precedes for practical use.

Conventionally, as a tooth profile is formed on a material of a shape in which a large diameter part and a small diameter part are coaxially formed next to each other, it is not a technique for manufacturing a multi-stage gear, but, for example, a tooth profile forming tooth pattern is provided around the tooth profile. A disk-shaped material is set in a die that is formed coaxially and adjacent to each other with a molding recess and a relief hole that is smaller in diameter than the molding recess and around which a tooth profile forming tooth mold is provided. In order to form a tooth profile around the material as well as to form a toothed boss by projecting a hole, JP-A-62-144
The method described in Japanese Patent No. 842 is known.

(C) Problems to be solved by the invention The conventional technique is a very rational idea in which the boss portion is projected by utilizing the punching by punching, and at the same time the tooth profile is formed. Since the size and shape of the tooth depends on the thickness of the material, the diameter of the escape hole and the punch, if the boss is prioritized, the shape of the tooth profile will be restricted, and conversely the shape of the tooth will be prioritized. However, the size of the material and the diameter of the punch will be restricted. Especially, if you want to form a multi-step gear by forming a tooth profile around the boss part, design everything from the beginning so that there is no missing or excess thickness even if you only change the tooth profile. I have to do it again.

Further, since the material is partially pressed in the axial direction and is not pressed by the material, there is a drawback that the tooth profile cannot be sufficiently extended to the corners of the tooth profile.

Therefore, until now, practically forged multi-stage gears have not been produced.

D. Means for Solving the Problems The present invention is a method for forming a multi-step gear capable of easily responding to changes in the tooth profile, and the structure is such that the die has a tooth profile forming tooth die. A molding recess provided and a relief hole having a smaller diameter than the above-described molding recess, around which a tooth profile forming tooth die is provided, are formed coaxially side by side, and the molding recess is released into the molding recess. A multi-stage gear is formed by pressing a multi-stage solid material having a diameter corresponding to a hole portion in the axial direction while applying uniform pressure to the entire surface.

E action By pushing force that acts evenly on the entire surface in the axial direction,
A force to expand the material in the radial direction acts on the material, and the material is extruded into the escape hole formed in the extruding direction. At that time, at the boundary between the molding recess and the relief hole, not only the meat flows along the plane parallel to the pushing direction of the relief hole, but also in the radial direction along the direction orthogonal to the pushing direction of the molding recess. Since a flow of meat is generated and it effectively acts as a strong overhanging force on the tooth profile forming tooth profile, the tooth profile is a shape that is faithful to the tooth profile forming tooth profile up to the end in the pushing direction. Is molded into.

A phenomenon in which a meat flow also occurs in the radial direction at the boundary between the molding recess and the escape hole is referred to by those skilled in the art as a segui effect.

Also, a multi-stage gear is effectively integrally formed on the peripheral surface of the relief hole by the flow of the wall in the axial direction. Further, by using a multi-stage solid material having a diameter corresponding to the forming recess and the escape hole, it is possible to easily cope with the tooth profile by only changing the material shape.

F. Example A method for forming a multistage gear according to the present invention will be carried out for a two-stage gear, and an example will be described with reference to the drawings.

1 is a die (lower die), 2 is a metal material, 3 is a punch (upper die), and the die 1 corresponds to a spur gear shape having a molding tooth die 5 for forming a tooth profile of a spur gear on the periphery. A molding recess 4 for
There is a molding tooth mold 5a for forming a meshing tooth for synchronization, and a corresponding escape hole portion 4a having a smaller diameter than the spur gear is dug coaxially, and the opening surface of the molding concave portion 4 faces upward. Fixed in posture.

The material 2 is a two-stage structure having a disk-shaped bulge 2a having a diameter corresponding to the escape hole on the lower surface of the disk having the same diameter as the reference pitch circle of the tooth profile forming tooth mold 5 in the molding recess 4. It is a real disc.

The punch 3 has the same diameter as the root circle of the tooth profile forming mold 5 in the forming recess 4 and is attached to the elevating body 6 which moves back and forth with respect to the inside of the forming recess 4 of the die 1 and contacts the material 2. At the periphery of the surface, a relief portion 3a is formed which is tapered and recedes in the opposite pushing direction.

Reference numeral 7 shown in the drawing is a knockout pin.

When such a raw material 2 is pushed into the molding concave portion 4 of the die 1 by applying a uniform pressure to the entire surface in the axial direction by the punch 3, first, the tooth profile forming tooth mold 5 is used by the tooth profile forming tooth mold 5 '. Is formed (Fig. 2), and then the material 2 is released into the relief hole 4a.
Then, the interlocking tooth 5'a for synchronization is also formed (FIG. 3).

In the process of forming the interlocking tooth 5'a for synchronization, a stress acts on the boundary between the disk-shaped bulging portion 2a of the material 2 and the radial direction with respect to the pushing direction.

The stress extends to the tip end portion P of the gear in the pushing direction, and the tooth portion is faithfully formed to the tip end portion P of the pushing direction (FIG. 4).

On the contact surface side with the punch 3, meat protrudes into the space of the escape 3a in the punch 3, so if the protruding portion is cut, the tooth profile becomes an effective part up to the end edge, and as shown in FIG. A spur gear 8 with meshing teeth 5'a is formed. Finally, if the shaft hole is penetrated, it will be a finished product.

Although the above-described embodiment has been described for the one provided with the synchro engaging tooth, the relief hole portion may be formed with a tooth profile forming mold other than the synchro engaging tooth, and the escape hole portion may be further formed. It is also possible to form two or more stepped portions by, for example, three stepped portions, and, as shown in FIG. 6, provide the tooth profile 10 on half of the width of the boss portion 9 of the third step. If it is applied to a gear having step portions (portions formed by the drop step portions) on both sides, it is not necessary to provide a relief in the punch.

As described above, according to the present invention, in the conventional molding of the bulging step portion,
It was not possible to control the phenomenon that the meat also flows in the radial direction, leading to a decrease in accuracy, but taking the flow of the meat in the wrong hand,
It can be said that it was epoch-making that it was effectively used to stretch the tooth tip at the end in the pushing direction. Moreover, by using a multi-stage solid material having a diameter corresponding to the molding recess and the escape hole, it is possible to easily cope with the tooth profile by only changing the material shape.

In other words, the tooth profile can be controlled by changing the material shape.

In the embodiment, a bulging portion having a small diameter is provided on the side surface of the material to allow the material to easily flow into the escape hole portion, but a flat disc-shaped material having no bulging portion may be used.

Further, the pushing means into the forming concave portion not only pushes into the forming concave portion of the fixed die by the punch, but also pushes the punch into the forming concave portion provided in the punch by the die to control the direction of the punch. You can also push it in the opposite direction.

Advantageous Effects According to the present invention, by applying a uniform pressure to the substantially entire surface of the material in the axial direction, it is possible to efficiently utilize the flow of meat and integrally mold a gear with high tooth top precision. Also, by using a multi-stage solid material having a diameter corresponding to the molding recess and the escape hole, it is possible to easily cope with the tooth profile by only changing the material shape.

[Brief description of drawings]

FIG. 1 is an explanatory view of an apparatus for carrying out a method for forming a gear according to the present invention, FIGS. 2 and 3 are explanatory views of a step of forming a gear by the apparatus, and FIG. 4 is a disk-shaped bulging portion. And FIG. 5 is an explanatory view of a molded gear, FIG. 6 is an explanatory view of a multistage gear product molded by the molding method of the modified embodiment, and FIG. 7 is a conventional example. FIG. 1 ... Die, 2 ... Material, 2a ... Disc-shaped bulge, 3 ...
Punch, 3a ... Relief, 4 ... Molding recess, 4a ... Relief hole, 5 ... (Spur gear) tooth profile forming tooth, 5a ... (Synchronizing meshing tooth) tooth profile forming tooth Mold, 5 '... Spur gear tooth profile, 5'a ... Synchro meshing teeth, 6 ...
Lifting body, 7 ... knockout pin, 8 ... spur gear, 9 ...
… Boss part, 10 …… Tooth profile, P …… Tip end in the pushing direction.

Claims (1)

[Claims] 1. A die is provided with a molding concave portion around which a tooth profile forming tooth die is provided, and a relief hole portion having a diameter smaller than that of the molding concave portion and having a tooth profile forming tooth die provided below the die concentrically. The multi-stage gear is formed by pressing a multi-stage solid material having a diameter corresponding to the molding recess and the relief hole into the molding recess by applying a uniform pressure to the entire surface in the axial direction. A method for forming a gear, which comprises: