JPS62168626A - Gear shaft of speed changer - Google Patents

Abstract

PURPOSE:To form a light weighted gear shaft by setting a gear, shaft core, and shaft hole on the shaft outside, partly pressing the outside of a small shaft part formed in both sides of the gear to form a spline part, and reducing the shaft hole. CONSTITUTION:A mandrel 3d is inserted into a shaft hole 1a of a long cylindrical billet formed from a short cylindrical billet, the long billet is pressed by an upper die 3c and a lower die 3b of an extrusion die 3B to make the outside diameter of an end of the long billet small and the long billet is named as a billet M3. Then, the billet m3 is reversed so that another end of the M3 is also made small. The billet M3 and the mandrel 3d are inserted into a spline forming die 3D and are passed through a spline projection 3p by a lower die 3b and an upper die 3c to form a spline 1e on the outside of the M3. In that time, recess parts of a shaft side spline is pressed from outside and swells into the shaft hole 1a to make a billet M5 having the reduced inner diameter. A speed changing gear 1b is engraved on the central large diameter part of the M5, is treated by a surface hardening, is subjected to a chemical polishing, and is finished to a prescribed dimension.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to machines such as gear shafts of motorcycles and vehicle transmissions, and camshafts of engines, which are manufactured by plastically processing materials by extrusion processing. This relates to gear shafts with high mechanical strength.

[Conventional technology and its problems]

Conventionally, the above-mentioned gear shafts are made by cutting a forged material to form a large diameter part where the gears are placed and a small diameter part representing the shaft part, and after making a shaft hole in the shaft center, the gears are formed by cutting or plastic working. is forming.

However, according to this manufacturing method, it is not easy to machine a long shaft hole provided at the center of the transmission shaft to reduce weight, and it is necessary to change the diameter of the shaft hole to maintain a constant wall thickness in the details. This made it difficult to reduce the weight of the transmission shaft, as there was a lot of wasted material.

[Object of the invention, outline of the structure]

The purpose of this invention is to reduce the weight of the transmission shaft as much as possible, by providing a gear on the outer surface of the shaft and a shaft hole in the shaft core, and forming small diameter shafts on both sides of the gear. It is characterized by forming a spline by partially pressing the outer surface of the small-diameter shaft portion by extrusion processing, and by reducing the diameter of the shaft hole of the spline portion.

[Effect]

The spline is formed by plastic working the outer surface of the material of the transmission shaft, and at this time only the valley part of the spline is pressed against the outer surface and bulges inward, so there is no decrease in the thickness of the spline part and the shaft part is Since there is no decrease in strength, there is no need to set the spline portion thick in advance, and the weight of the speed change shaft can be reduced.

〔Example〕

Hereinafter, the present invention will be described with reference to the illustrated embodiment. In FIG. 2, reference numeral 1 denotes a transmission shaft of a vehicle transmission, which has a shaft hole 1a for oil supply in the center, and a transmission gear in the center on the outer periphery. 1bf:
In addition, other speed change gears 2. are provided on both sides of the speed change gear 1b.
A shaft portion 1C that supports the transmission shaft 52 and a bearing portion 1d that supports the transmission shaft 1 in the case are provided. Reference numeral 1e denotes a hexagonal spline formed on the shaft portion 1C, which locks the other transmission gear 2.2 only in the rotational direction.

This transmission gear 1 is manufactured as follows. That is, as shown in FIGS. 1 and 3 and below, first prepare a material M1 having a short outer cylindrical shape as shown in FIG. The second material M2 is then stretched to a length of , and a second material M2 as shown in the figure) is manufactured. Note that the extrusion die 3A is the bed 3 of a press machine.
It consists of a lower mold 3b installed on a ram and an upper mold 3c installed on a ram. 3d is a mandrel attached to the upper die 3c so that it can be moved up and down by a small amount within the support hole 3h provided in the upper die 3c.

Further, the drawings from FIG. 4 onward are also different only in the shape of the product to be molded, and since there is no essential difference, detailed explanation will be omitted. Note that in FIGS. 4 and below, the reference numeral 3e indicates a knockout for removing material attached to the lower die 3b.

The operation of the extrusion die 3A is as follows. When the upper mold 3c descends, the material M1 inserted into the lower mold 3b is pressed by the lower surface of the upper mold 3c and pushed into the lower mold 3b. It is extruded to the lower part through the molding part 3j.

At this time, the material M1 becomes smaller in diameter and expands in the axial direction to form a long cylindrical second material M2 that is used for the next process. As described above, when the first extrusion process is finished, the upper mold 3C rises, but at this time, the upper mold 3C first rises slightly, and the upper mold 3C and the second material M2 are slightly separated, and the second material During the movement distance until the diameter of M2 expands a little and the mandrel 3d loosens its tightening, the mandrel 3d remains in the shaft hole 1a of the second material M2 and is prevented from being cut.

Next, as shown in FIG. 4, insert the mandrel 3d into the shaft hole of the second material M2, put it into the lower mold 3b of the second extrusion mold 3B, lower the upper mold 3C, and adjust the outer diameter of the end. is extruded to a small diameter to form a third material M3, and then the third material M3 is inverted to form a third extrusion mold 3C shown in FIG.
1 (d) by lowering the upper mold 3C and lowering the upper mold 3C.
) is formed.

Next, as shown in FIG. 6, the fourth material M4 is pushed into the spline mold 3D, passes through the spline protrusions 3p formed on the lower mold 3b and the upper mold 3C, and is extruded up and down, so that the outer diameter part A spline 1e is formed on. At this time, in order to reduce the extrusion force, the root diameter of the spline protrusion 3p is set to the fourth diameter.
The outer diameter of the spline portion of the material M4 is smaller than the outside diameter. During this spline forming process, the trough of the spline is pressed from the outer surface and bulges into the shaft hole, so the inner diameter of the fourth material M4 contracts, and the wall thickness of the shaft does not change significantly. .

The transmission gear 1b is carved into the central large diameter part of the plastically worked material thus obtained by gear cutting or other machining, or by rolling or other plastic working, and the surface is carburized and quenched or other appropriate heat treatment is performed. After hardening and chemically polishing to remove the oxide film, the teeth and shaft are finished to predetermined dimensions by grinding to complete the machining.

〔Effect of the invention〕

As described above, this invention provides a gear on the outer surface and a shaft hole in the shaft core, and extrudes both sides of the gear to form a small diameter shaft. Therefore, it is possible to process thick and short materials for the first time. If a shaft hole is provided, the length of the shaft hole will increase as the shaft expands.
The process of drilling the shaft hole by machining can be reduced. In addition, since the outer diameter part of the small diameter part is extruded and pressed to form a spline, when performing spline processing, only the valley part of the spline is pressed against the outer surface.
Moreover, since the inner diameter is small, there is no decrease in wall thickness and no decrease in strength of the shaft portion. Furthermore, it is no longer necessary to set the wall thickness of the small diameter portion thick in advance in anticipation of a reduction in wall thickness, which has the remarkable effect of reducing the weight of the speed change shaft.

[Brief explanation of drawings]

171] shows an embodiment of the present invention, FIG. 1 is a cross-sectional view of a speed change gear, FIG. 2 is a cross-sectional view of the gear in the middle of plastic working, and FIG. 3 is a process diagram showing the process of plastic working. ,
FIG. 4 to FIG. 7 are cross-sectional views of the mold showing each step of extrusion processing. 1... Speed change shaft, 1a... Shaft hole for oil supply, 1b...
...Speed gear, 1C...shaft, 1d...9 bearing, 1Cφ conflict...hexagonal spline. Patent Applicant: Yamaha Motor Co., Ltd. Agent Several pieces of Yamakawa (and 2 others) Crane 1 drawing ~ continuation (■i original (self-proposal) Showa year, month, day, 61.3.5

Claims (3)

[Claims] (1) Provide a gear on the outer surface of the shaft and a shaft hole in the shaft center, form a small diameter shaft on both sides of the gear, and press the outer surface of the small diameter shaft partially by extrusion processing to form a spline. A gear shaft of a transmission, which is formed by reducing the diameter of the shaft hole of the spline part. (2) A gear shaft for a transmission according to claim 1, wherein the spline is a hexagonal spline. (3) The gear shaft for a transmission according to claim 1, wherein the small diameter portions provided on both sides of the gear are also formed into a cylindrical shape by extrusion processing.