JPH0773770B2 - Guide gear forming method and forming apparatus thereof - Google Patents

Description

Description: INDUSTRIAL APPLICABILITY The present invention relates to molding of a guide gear in which a tooth profile of a guide gear having a chamfered straight tooth profile with an inverse taper is integrally formed on a gear body by a forging means. The present invention relates to a method and a molding apparatus therefor.

(B) Conventional Technique As a technique for forming the tooth profile in the guide gear described above, a manufacturing apparatus disclosed in, for example, Japanese Patent Laid-Open No. 3-204133 is known.

In the apparatus, the tooth profile forming space is divided into a chamfer part side formed on the die and a straight part side formed on the punch, and the punch is an inner punch for press and the tooth profile. It is configured with an outer punch that restrains the opposite side of the chamfer in the part forming space.

(C) Problems to be Solved by the Invention In the above conventional device, the space for forming the tooth profile is divided into two parts on the plane orthogonal to the axis from the boundary between the chamfer part and the straight part. Even if the reverse taper is provided, the mold can be easily released by dividing the mold from the dividing surfaces.

However, in forging gears, especially in cold forging, the pressing pressure is so high that not only cracks are likely to occur at the chamfer tip, but there is also the risk of damage, leaving the die having a fatal drawback that it will not last long. However, it cannot be put to practical use yet.

D. Means for Solving the Problems The present invention enables the practical production of guide gears by forging, and the structure is divided into two in a plane orthogonal to the axis from the boundary between the chamfer portion and the straight portion. At the same time, the chamfer portion side divided into two parts is characterized in that meat is further projected from the tip of the chamfer into the tooth profile forming space of the die divided by a plane parallel to the axis and passing through the axis. The guide gear forming method and the tooth profile forming space are divided into two parts on the plane orthogonal to the axis from the boundary between the chamfer part and the straight part, one of which is formed into a punch and the other side is formed into a die. Further, there is provided a guide gear forming device in which the chamfer portion side divided into two parts is divided by a plane parallel to the axis and passing through the axis from the tip of the chamfer portion.

E action In the upsetting process in which a pressing force is applied to the material by the punch and die in the axial direction, the material is deformed in the axial direction, and the pressing force also causes the material to overhang in the radial direction, filling the tooth profile shape forming space with meat. Thus, the tooth portion is molded.

At that time, since the chamfer portion side is divided by a plane that is parallel to the axis and passes through the axial center from the tip of the chamfer portion, each divided piece expands in the radial direction against excessive pressure, and the stress is absorbed. When the pressure is reduced, the pieces are gathered in the central direction by the reaction and a pressing force is exerted to shape the tooth profile.

F. Embodiments A guide gear forming method and apparatus according to the present invention will be described with reference to the drawings for a clutch gear.

In FIG. 1, 1 is a die, 2 is an inner punch, 3 is an outer punch, and the die 1 is fixed to a base,
A recess 1a corresponding to the boss portion of the clutch gear to be molded is provided in the center, and a tooth profile forming space 7a corresponding to the chamfer portion of the tooth profile of the guide gear formed around the clutch gear is provided around the periphery. Is provided.

Further, a mandrel 4 is axially penetrated in the center of the recess 1a.

The outer punch 3 is arranged around the inner punch 2, and the outer punch 3 and the inner punch 2 constitute a tooth profile forming space 7b corresponding to a straight portion provided with a reverse taper 8 for preventing slipping out. It is supposed to be done.

The die 1 and the outer punch 3 are divided into two in a plane orthogonal to the axis from the boundary between the chamfer portion and the straight portion, and the inner punch 2 is directly moved back and forth in the axial (vertical) direction by a hydraulic press or the like. The outer punch 3 is actuated and is moved forward and backward in the axial direction through the urethane material 5 by the hydraulic press or the like prior to the inner punch 2.

Into the die 1, a doughnut-shaped material 6 having an inner diameter that allows the mandrel 4 to be inserted thereinto is set, and pressing force can be applied to the material 6 by both punches 2 and 3.

As a result, when the inner punch 2 is lowered, the chamfer portion formed on the die 1 is surrounded by the material 6 as shown in FIG. 3 which shows one tooth profile forming space in the AA cross section of FIG. The corresponding tooth profile forming space 7a and the tooth profile forming space 7b corresponding to the straight portion formed by the inner punch 2 and the outer punch form the tooth profile forming space 7 having a closed tooth profile. .

Further, the die 1 is divided into left and right from a tip of a tooth profile forming space 7a corresponding to a chamfer, by a plane F parallel to the axis and passing through the axis.

In addition, below the fixed die 1, an ejector pin 9 protruding into the recess 1a is provided.

A method of forming a clutch gear by using the die 1 and both punches 2 and 3 thus formed will be described.
When the punches 2 and 3 are raised, the material 6 is set in the die 1 (FIGS. 1 and 4).

Next, when a pressing force is applied to the punch by a hydraulic press, the outer punch 3 first comes into contact with the upper surface of the die 1, and then the inner punch 2 also comes down while compressing the urethane material 5 and comes into contact with the upper surface of the material. A tooth profile forming space 7 is formed around the material 6.

Then, when the material 6 is crushed by further lowering the inner punch 2, the material 6 swells in the radial direction and projects into the tooth profile forming space 7.

Thus, in one step, the doughnut-shaped material 6 is formed into a guide gear having a tooth-shaped straight portion provided with a reverse taper 8 for preventing slippage (FIG. 5).

Finally, both punches 2 and 3 are raised, and the clutch gear 6'completed by the ejector pin 9 is pushed upward.

In the above embodiment, an example in which the tooth profile is projected from the donut-shaped material to the outer periphery thereof is explained. However, when the tooth length is large, as shown in FIG.
It is also possible to use a material 6 that has a protrusion 6a that is close to the product shape and that can be set in the tooth profile forming space 7a of the fixed die 1 on the outer circumference. The pressure can be reduced.

Further, as the molding device, the one in which the chamfer part of the material is set so as to be on the punch side has been described, but it is also possible to perform the molding by a device for setting the material in the opposite direction. It will be described with reference to FIG.

As shown in FIG. 8, this apparatus comprises a fixed die 1'having a tooth profile forming space 7b, an inner punch 2'for restraining the upper surface of the material, and an outer punch 3 descending prior to the inner punch 2 '. ′ And the tooth profile forming space 7 represents one tooth profile forming space in the BB cross section of FIG. 10, as shown in FIG. 7, the fixed die 1 ′, the inner punch 2 ′ and the outer. It is formed by the punch 3 '.

Further, on the punch side, the tooth profile forming space corresponding to the chamfer part obtained by dividing the tooth profile into two parts from the boundary between the chamfer part and the straight part on the plane orthogonal to the axis is parallel to the axis from the tip of 7a. It is divided into left and right by a plane F passing through the heart.

The material 6 is set, and the outer punch 3'is lowered first,
(FIG. 9), and subsequently, the inner punch 2'is lowered to form a space 7 for forming a tooth profile (FIG. 10), and a series of operations are performed.

The device of this embodiment enables efficient molding due to the interposition of the urethane material, reduces the load on the mold due to the processing pressure, and applies the reverse taper to prevent the tooth profile straight part from slipping off only by the plastic processing technology. The formation of the clutch gear thus completed can be completed in one step.

In addition, the space for forming the tooth profile part is divided into two parts on the plane perpendicular to the axis from the boundary between the chamfer part and the straight part, and the other part is formed into a punch, the other side is formed into a die, and the chamfer part side from the tip of the chamfer to the axis. Other configurations need not be limited to the embodiments as long as they have a configuration that divides in the direction.

Effect According to the present invention, since the chamfer side of the mold is divided in the axial direction from the tip of the chamfer, even if an excessive pressure is applied, stress is not absorbed by the dividing surface and the die is not destroyed. No further cracks will occur in the part divided from. Further, when the pressure is reduced, the contracting force works to shape the tooth profile.

In this way, it is possible to put into practice the formation of a guide gear in which the straight taper of the tooth profile is provided with a reverse taper for preventing slippage, by merely making one movement of the punch.

[Brief description of drawings]

The drawings show a method for molding a gear according to the present invention. FIGS. 1 and 2 are explanatory views showing the structure of a molding apparatus, FIG. 3 is an explanatory view of a tooth profile forming space, and FIG. FIG. 5 is an explanatory view of a material before processing, FIG. 5 is an explanatory view of a state of being processed into a clutch gear, FIG. 6 is an explanatory view showing a modification example of the material, and FIG. 7 is a modification example of a tooth profile forming space. Explanatory drawing, FIGS.
FIG. 10 is an explanatory view showing the structure of the molding apparatus in the modified embodiment. 1, ... Die, 1 '... Fixed die, 1a ... Recess, 2,
2 '... inner punch, 3', outer punch, 4 ... core, 5 ... urethane material, 6 ... material, 6 '
...... Clutch gear, 6a …… Projection, 7 …… Space for tooth profile formation, 7a …… Space for tooth profile formation corresponding to chamfer,
7b ...... Tooth profile forming space corresponding to the straight part, 8 ...
... reverse taper, 9 ... ejector pin.

Claims (2)

[Claims] 1. A method of forming a guide gear having a tooth profile in which a straight portion of a chamfered straight tooth profile is provided with an inverse taper, in a surface orthogonal to an axis from a boundary between the chamfer portion and the straight portion with respect to the tooth profile. The meat is divided into two parts, and the divided chamfer part side is further extended from the tip of the chamfer into the tooth profile forming space of the mold which is divided by a plane parallel to the axis and passing through the axis. A method for forming a guide gear, which is characterized in that 2. The tooth profile forming space is divided into two parts on the plane perpendicular to the axis from the boundary between the chamfer part and the straight part, one of which is formed into a punch and the other side is formed into a die. An apparatus for forming a guide gear, wherein the chamfer portion side divided into two is divided by a plane parallel to the axis and passing through the axis from the tip of the chamfer portion.