JPH0673712B2 - Method for manufacturing speed change gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a forged reverse taper-shaped spline tooth formed on the outer periphery of the boss portion of a speed change gear used in a synchromesh transmission to the root of the boss portion. The present invention relates to a method for manufacturing a speed change gear for forming.

[Conventional technology and its problems]

The clutch spline toothed speed change gear used in the conventional synchromesh type transmission is a method in which the gear blank is provided with a stub for machining the spline tooth at the root of the spline tooth and is machined integrally with the speed change tooth portion. , And the clutch spline tooth portion which is reverse tapered with the gear shift tooth portion are individually manufactured by machining or cold forging, and the clutch spline tooth portion is fitted to the outer periphery of the gear tooth portion that is finished with high precision. There is a method in which the outer surface of the joint is integrated by electron beam welding.

The former has a drawback that the effective length of the spline tooth is shortened because the root of the spline tooth is provided with a hollow. Further, the latter has a drawback that the metal flow between the spline tooth portion and the speed change tooth portion is cut off, the strength is weakened, mechanical processing and welding assembly processing are required, and the cost becomes high.

A method has been proposed in which the two-division type is improved to integrally form the speed change tooth portion and the spline tooth portion in the forging step (see, for example, Japanese Patent Publication No. 49-11543 and Japanese Patent Publication No. 52-61162). . However, in the former case, the spline teeth are linear and the inverse tapered spline teeth cannot be formed. Further, in the latter, it is shown that the spline teeth are inversely tapered to the boss portion and integrally formed by cold forming, but the root portions of the spline teeth are cut (see FIG. 3 of the publication). Therefore, also in the latter case, the effective length of the spline teeth is short as in the former case, and cutting is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a speed change gear in which an inverse tapered spline tooth can be formed up to the root of a boss portion only by a forging step and the effective length of the spline tooth can be increased.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a speed change gear, including: (a) a boss having a diameter smaller than that of the speed change tooth portion formed integrally with the speed change tooth portion, having a chamfer at the tip, and finishing A step of forming a spline tooth parallel to the gear axis smaller than the size by forging, (b) a step of expanding the shaft hole formed in the boss portion by cold coining to form the spline tooth into a spline tooth of a predetermined size , (C) The die arranged radially with respect to the gear axis is forcedly slid toward the center of the gear in the direction perpendicular to the gear axis by pressing the die with the inclined die pressing surface of the cam while pushing down the cam. Forming a reverse taper spline tooth to the root of the boss by pushing the spline teeth between the spline teeth, and Guided by a pin that is inclined and inclined to the cam in parallel with the cam, it is forced to slide outward from the center of the gear in the direction perpendicular to the gear axis, and the mesh between the die and the inverse tapered spline teeth is released. The gist is that it consists of each process.

〔Example〕

 Next, the present invention will be described based on the embodiments shown in the drawings.

FIG. 1 is a front view showing a speed change gear manufactured by the manufacturing method of the present invention. Reference numeral 1 is a gear, 2 is a speed change tooth formed on the outer periphery of the gear, for example, a helical tooth, and 3 is the gear 1 One side of the boss has a diameter slightly smaller than the outer diameter of the gear. The boss 3 is formed integrally with the main body 1 of the gear and the outer peripheral surface of the boss 3 serves to prevent the mission from coming off. To form the inverse tapered spline teeth 4. The spline teeth 4 reach the root of the boss 3, that is, the connection with the gear.

Next, a method for manufacturing the above-mentioned speed change gear will be described.

Steel materials that can be used as gears, such as SC steel, SCM steel, SNC
Steel, SNCM steel, SCR steel, etc. are generally cut into bars suitable for the size, shape, diameter, etc. of the gear to be manufactured (Fig. 3 (1)). The material W cut into the required length is heated by setting the heating temperature according to the type, size, and weight of the material so that the material W has a temperature suitable for hot forging. This heated material W is upset into the material HW by hot forging in the upsetting process according to the shape of the gear to be formed (Fig. 3 (2)). In this case, the upset outer diameter is adjusted to the outer diameter of the gear to be manufactured so as to be suitable for the plastic working in the next step.

Next, the installed material HW is put into a forging die once or through a plurality of steps such as roughing and finishing steps so that the speed-changing tooth profile and the groove part to be the spline tooth are formed like the material FW. It is integrally formed (Fig. 3 (3)). The spline teeth 4 formed by this forging die are made slightly smaller than the finish size, and then the tooth profile is made to have a predetermined size and accuracy in a cold coining process in which the surplus inside the shaft hole is plastically processed to the outside of the material. To have.

Then, as a pretreatment of this cold coining step, a shaft hole 5 is bored in the material FW having the outer shape of the gear (FIG. 3 (4)). In this case as well, the diameter of the shaft hole 5 is smaller than the set shaft hole diameter, and the shaft hole portion has a surplus portion. After this perforation step, other necessary post-treatment steps such as normalization and shot blasting may be performed if necessary.

The material FW on which the spline teeth have been previously formed in this manner is then sent to the cold coining step 5. This cold coining pushes the surplus inside the shaft hole toward the outside of the material so that the spline teeth have a predetermined size and accuracy (Fig. 3 (5)). The material in which the spline parallel to the gear axis is formed in this manner is sent to the step of forming the inverse tapered spline tooth (FIG. 3 (6)). The forming of the inverse tapered spline teeth is performed using the manufacturing apparatus shown in FIG. 4 and subsequent figures.

Next, an apparatus used in the step of forming the inverse tapered spline tooth will be described.

The upper die 11 is attached to the upper die mounting base 12 in a spring-pressed state, and the lower die 13 facing the upper die 11 is a lower die mounting base.
A punch 15 fixed to the lower die mounting base is projected through the lower die 13 and a cylindrical knockout cylinder 16 is provided on the outer periphery of the punch 15, and the lower die mounting base is further mounted. The annular case 17 is fixed. When forming a tooth profile in this case 17 in the process of forming a reverse tapered spline tooth, a large number of cam fitting holes 17H matching the inter-tooth angle and the number of teeth of this gear are formed at a constant pitch and the cam fitting The inner surface on the outer peripheral side of the hole 17H is defined as a cam pressing surface 17F, and the cam pressing surface is perpendicular to
And a plane perpendicular to the longitudinal axis of the die,
The cams 21 are fitted into the respective holes 17H. In addition, the spring mounted on the lower die mount 14 is mounted on the lower die mount 14.
An annular flange 18 supported by 24 is provided, and the bottom of the cam 21 fitted in the cam fitting hole is supported by this flange, and the cam 21 is bolted to the flange 18.

The cam 21 is finished in a flat shape with high precision so that its back surface contacts the cam pressing surface 17F.
An upper end side of the die 22 is projected and fixed such that the die 22 inclines inward, and a die pressing surface 21T having an inclination angle equal to the inclination angle of the pin 22 is formed on the inner side surface of the cam and facing the pin 22.

As shown in FIGS. 6 and 7 in the upper part of the lower mold 13, die fitting insertion holes 13H are formed at predetermined angles in line with the straight line toward the center of the lower mold which is adjusted to the inter-tooth angle of the gear. The die fitting insertion hole 13H has a circular cross section, and the top portion thereof is cut into a flat shape so as to have an open shape.
The dies 23 each having a round bar shape and whose top surface is cut in a flat shape are fitted into H and arranged radially, and the case 17 holds down the flat surface of the dies to prevent the dies 23 from rotating. At the tip of this die 23, each inter-tooth groove of the gear can be formed into a predetermined inverse tapered spline tooth.

In addition, the material FW installed in the lower mold 13 is moved to the upper mold 11 to lower the die.
After forming the inverse tapered spline teeth at 23, this material
When the FW is taken out from the lower mold, the knockout pins 19 and 20 and the knockout cylinder 16 can be easily taken out.
The length of the knockout pins 19 and 20 is determined so that the knockout pin 19 pushes up the flange 18 quickly and then the knockout pin 20 pushes up the knockout barrel 16. This pulls the die 23 outward from the teeth of the material FW,
So that it protrudes from inside the lower mold 13.

Next, a forming process of the inverse tapered spline tooth using this device will be described.

A material FW having spline teeth formed in advance by a forging process is set in the lower mold 13.

By lowering the upper die mount 12, the spring-biased upper die 11 is lowered together with the upper die mount 12, and the material FW is sandwiched between the upper die 11 and the lower die 13.

When the upper die mount 12 descends, the upper surface of the cam 21 is pressed with a slight delay after the material FW is clamped. As a result, the cam 21 and the flange 18 are pushed down, whereby the rear end of the die 23 is pushed by the inclined die pressing surface 21T of the cam 21, and each die 23 slides in the direction toward the center and At 23D, the spline groove of the material FW is formed into a predetermined inverse tapered spline tooth.

Raise the upper die mount 12 and push up the knockout pin 19. As a result, the cam 21 ascends via the flange 18, but the pin 22 that is inclined and projected on the cam 21 penetrates the through hole 23H formed at the rear end of the die 23. As the pin 22 rises, the die 23 is forcibly slid in the outward direction and returned.

After the tip of the die 23 is separated from the material FW, the knockout pin 20 is pushed up. This allows the knockout cylinder 16
Is pushed up, material FW through this knockout cylinder 16
Is taken out from within the lower mold 13.

The push-up of the knockout pin 19 and the knockout pin 20 is released, and the following steps are repeated.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the speed change gear which has a reverse taper-shaped spline tooth to the root of a boss can be manufactured inexpensively and accurately only by a forging process, Moreover, since the speed change gear obtained has metal flow, strength In addition, since the effective length of the spline teeth can be increased, the total length of the gear can be shortened as compared with the conventional product, and the speed change gear can be downsized.

In particular, the present invention forcibly presses the die radially arranged with respect to the gear axis toward the center of the gear in a direction perpendicular to the gear axis by pressing the cam with the inclined die pressing surface of the cam. By sliding to form the reverse taper spline teeth up to the root of the boss, the die is guided by a pin protruding with the cam inclined parallel to the inclined die pressing surface of the cam while pushing up the cam. , Forcibly sliding outward from the center of the gear in the direction perpendicular to the gear axis to disengage the die and the inverse taper spline teeth, so even if the tip of the die firmly digs into the material, It is possible to force the die to separate from the material exactly outward from the center of the gear in a direction perpendicular to the gear axis, thus damaging the formed inverse taper spline teeth. No it can be molded accurately inverse tapered spline until boss root of the gear.

[Brief description of drawings]

FIG. 1 is a front view of a speed change gear manufactured by the method of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is an explanatory view showing a manufacturing process, and FIG. 4 is a drawing of an inverse tapered spline tooth. FIG. 5 is a cross-sectional view of the manufacturing apparatus to be carried out, FIG. 5 is a cross section thereof, FIG. 6 is a plan view of the lower mold, FIG. 7 is a front view showing a part of the lower mold, and FIG. 8 is an explanatory view of the die. 1 is a gear, 2 is a helical tooth, 3 is a boss portion, 4 is a spline tooth, W, HW, FW are materials, 11 is an upper die, 13 is a lower die, 17 is a case, 18 is a flange, 21 is a cam, 21T Is a die pressing surface, 22 is a pin, and 23 is a die.

Claims (1)

[Claims] 1. A method for manufacturing a speed change gear, comprising: (a) a gear boss having a diameter smaller than that of a speed change tooth portion and having a chamfer at its tip, and a gear axis smaller than a finished dimension. A step of forming parallel spline teeth by forging, (b) a step of expanding the shaft hole formed in the boss portion by cold coining to form the spline teeth into spline teeth having a predetermined size, (c) a gear axis line The die arranged radially with respect to is pressed by the inclined die pressing surface of the cam while pushing down the cam, forcibly sliding it toward the center of the gear in the direction perpendicular to the gear axis, and Forming a reverse taper spline tooth to the root of the boss by pushing in (d) tilting the die into the cam in parallel with the inclined die pressing surface of the cam while pushing up the cam. Guided by the protruding pin, it is forced to slide outward from the center of the gear in the direction perpendicular to the gear axis, and the process of disengaging the die and the inverse tapered spline teeth is performed. And a method for manufacturing a speed change gear.