JPH04366028A - Manufacturing device for transmission gear - Google Patents

Abstract

PURPOSE:To lengthen effective length of a groove by forming a reverse-tapered spline groove, which is formed on the periphery of the root of a gear boss by forging. CONSTITUTION:A die 23 according to the number of teeth of a gear material formed by forging a splined gear in parallel with a gear 1 is set slidably to face toward the axis of the gear 1, and inserted into a lower die 13 to be supported. Then a cam 21 forced down by lowering of an upper die 11 opposed to the lower die 13 is supported slidably in the vertical direction on a case 17 provided on a lower die mounting table. Thus a contact surface of the cam 21 made in contact with the die 23 at the rear end is made aslant so that the die 23 is moved in the direction of the axis of the gear when the cam 21 is pressed down, and a parallel splined gear is formed in the reverse-tapered shape in a gear axis line.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for manufacturing a transmission gear used in a synchromesh type transmission, in which a reverse tapered spline groove is formed on the outer periphery of a boss portion of the gear, extending all the way to the root of the boss portion. It is.

0002

[Prior Art] A transmission gear with clutch spline teeth, which is conventionally used in a synchromesh type transmission, is machined integrally with the transmission teeth by providing a clearance at the root of the spline for machining the spline from a gear blank. The method of forming the gear teeth and the clutch spline tooth part, which has an inversely tapered tooth profile, are manufactured individually by machining or cold forging, and the clutch spline teeth are formed on the outer periphery of the gear gear tooth part, which is finished with high precision. There is a method of fitting them together and integrating the outer surfaces of this joint by electron beam welding. The former has the disadvantage that the effective length of the spline is shortened because a clearance is provided at the base of the spline. In addition, the latter has the drawback that the metal flow between the spline tooth portion and the speed change tooth portion is broken, weakening the strength, and requiring machining and welding assembly processing, resulting in high cost.

[0003] A method of improving this two-part system and integrally forming the transmission tooth part and the spline tooth part in a forging process has been proposed in, for example, Japanese Patent Publication No. 49-11543 and Japanese Patent Application Laid-Open No. 52-61162. There is. However, in the former case, the spline groove is straight and a reverse tapered spline groove cannot be formed. In the latter case, it is shown that the spline groove is inversely tapered to the boss portion and integrally molded by cold forming, but the root portion of the spline groove is machined. (See Figure 3 of the bulletin)

Therefore, in the latter case as well, the effective length of the spline groove is short, and cutting is required.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to form a spline groove using only a forging process and to increase the effective length of the spline groove.

[0006]

[Means for Solving the Problems] The present invention has been made to achieve the above-mentioned object, and a gear having gear shifting teeth formed on the outer periphery is integrated with a boss portion having a diameter smaller than the diameter of the gear. A spline groove is formed on the outer peripheral surface, and this inversely tapered spline groove is formed by forging up to the root of the boss. This inverted taper spline groove is formed by forging a spline groove parallel to the gear axis using a number of dies corresponding to the number of teeth of the gear material, which are slidable toward the gear axis and then fitted into the lower die. A cam that is inserted and supported and pushed down by the lowering of the upper die facing the lower die is supported so as to be able to slide vertically in a case provided on the lower die mounting base, and is abutted at the rear end of each die. This is done using a device in which the die contact surface of each cam is an inclined surface such that the die moves in the direction of the gear axis when the cam is pressed down.

[0007]

[Example] Fig. 1 is a front view showing a transmission gear manufactured by the manufacturing apparatus of the present invention, in which 1 is a gear, 2 is a transmission tooth formed on the outer periphery of this gear, such as a helical tooth, and 3 is a helical tooth. A boss part on one side of the gear 1 has a diameter slightly smaller than the outer diameter of the gear.This boss part 3 is molded integrally with the main body 1 of the gear, and the outer peripheral surface of the boss part 3 has a transmission hole. A reverse tapered spline groove 4 for stopping is formed. This spline groove 4 is designed to reach the root of the boss portion 3, that is, the connection portion with the gear portion.

[0008] Next, an apparatus and method for manufacturing a transmission gear according to the present invention will be explained. Steel materials that can be used as gears, such as SC steel, SCM steel, SNC steel, SNCM steel, and SCR steel, are generally made to be suitable for the size, shape, diameter, etc. of the gear for which the bar material is manufactured. disconnect. The raw material W cut to the required length is then heated at a heating temperature determined according to the type, size, and weight of the raw material so that the temperature is suitable for hot forging, that is, plastic working. The heated material W is upset-formed like HW by hot forging, that is, plastic working, in an upsetting process in accordance with the shape of the gear to be formed. In this case, the upsetting outer diameter is matched to the outer diameter of the gear to be manufactured so as to be suitable for the next step of plastic working.

Next, the upholstered material HW is put into a forging die and subjected to one process or multiple processes such as a rough process and a finishing process to form the gear tooth profile and the groove part that will become the spline tooth.
Formed in one piece like this. The protruding part between the spline grooves 4, 4 formed by this forging die is made slightly smaller than the predetermined tooth profile, and then the cold coining process is performed in which the excess inside of the shaft hole side is plastically worked to the outside of the material. to ensure that the tooth profile has the specified accuracy. In the next step, a shaft hole 5 is bored in the material FW on which the outer shape of the gear has been formed. In this case as well, the diameter of the shaft hole 5 is made smaller than the set shaft hole diameter, and the shaft hole portion is provided with an extra thickness. After this drilling process, other necessary post-processing processes such as normalizing and shot blasting may be performed as necessary.

[0010] The material FW in which the spline groove shape has been formed in advance in this manner is then sent to a cold coining step 5. This cold coining pushes the extra wall inside the shaft hole side to the outside of the material so that the spline has a predetermined accuracy. The material in which splines parallel to the gear axis have been formed in this manner is sent to a reverse slope forming step 6. Reverse gradient molding is performed using a manufacturing apparatus as shown in FIG. 4 and subsequent figures.

Next, this manufacturing apparatus will be explained. The upper die 11 is attached to an upper die mount 12 in a spring-pressed state, and the lower die 13 facing the upper die 11 is fixed to a lower die mount 14, and a punch 15 is provided to protrude from the lower die mount 14. is passed through the inside of the lower mold 13, and this punch 15
A cylindrical knockout tube 16 is disposed around the outer periphery of the mold, and an annular case 17 is further fixed to the lower die mounting base. This case 1
7, when shaping the tooth profile in the reverse slope forming process, a large number of cam fitting holes 17H are drilled at a constant pitch that match the inter-tooth angle and number of teeth of this gear, and the outer peripheral side of the cam fitting holes 17H are drilled. The inner surface is a cam pressing surface 17F, and this cam pressing surface is a plane that is vertical and perpendicular to the longitudinal axis of the die, and a cam 21 is fitted into each hole 17H. Further, an annular flange 18 supported by a spring 24 attached to the lower mold mount is disposed on the lower mold mount 14, and this flange supports the bottom of the cam 21 that is fitted into the cam insertion hole. The cam 21 is bolted to the flange 18 for support.

The cam 21 is flat and finished with high precision so that its back surface touches the cam pressing surface 17F, and a pin 22 is fixedly protruding from the inside of the lower part with the upper end inclined inward. At the same time, a die pressing surface 21T having an inclination angle equal to the inclination angle of this pin 22 is formed on the inner surface of the cam and facing the pin 22.

As shown in detail in FIGS. 6 and 7, die fitting holes 13H are formed in the upper part of the lower mold 13 at predetermined angles along a straight line toward the center of the lower mold that matches the inter-tooth angle of the gear. At the same time, the die insertion holes 13H have a circular cross section, and the tops thereof are cut into a planar shape and are open. In each of the die insertion holes 13H, there is provided a die 23 having a round bar shape and whose upper surface is cut into a planar shape. are respectively fitted and arranged radially, and the case 17 presses down the flat surface of the die to prevent the die 23 from rotating. At the tip of this die 23, each interdental groove shape of the gear can be shaped into a predetermined reverse taper spline groove.

Further, after the material FW loaded in the lower mold 13 is lowered by the upper mold 11 and a reverse taper spline groove is formed by the die 23, when the material FW is taken out from the lower mold, the knockout pins 19, 20 and It is made to be easily taken out with a knockout cylinder 16. The lengths of the knockout pins 19 and 20 are determined so that the knockout pin 19 quickly pushes up the flange 18 and the rear knockout pin 20 pushes up the knockout cylinder 16. This allows the die to be
After pulling outward from the teeth of W, the material FW is made to protrude from inside the lower mold.

[0015] Using the manufacturing apparatus configured as described above, the material FW, in which spline grooves have been previously formed in a forging process, is set in the lower die. Next, when the upper mold is lowered, the material FW is held between the upper and lower molds by the upper mold under the pressure of the spring, and the upper surface of the cam 21 is also gripped a little later than when the material is clamped by the lowering of the upper mold. Pressed. At this time, since the lower mold is fixed, the cam 21 and flange 18 are pushed down by the lowering of the upper mold, so that the rear end of the die 23 is pressed down by the tapered die pressing surface 21T of the cam. When pressed, each die slides in a direction toward the center of the lower mold, and the spline groove shape of the material is shaped into a predetermined reverse taper spline groove at the die tip 23D. Thereafter, the upper die is raised and the knockout pin 19 is pushed up, thereby also returning the flange 18. When the flange returns or rises, the cam 21 is also raised, but since the rear end of the die is connected through a pin 22 that projects obliquely from the cam, when the pin 22 rises, the cam 21 also rises. Since the die 23 is fitted into the lower mold 13 and can only slide radially, the die 23 is moved back and returned to its original position.

After the tip of the die separates from the tooth profile of the material FW, the knockout pin 20 and the knockout tube 1 are removed.
At step 6, the material FW is pushed up from within the lower mold and taken out from the lower mold.

[0017]

[Effects of the Invention] According to the present invention, a gear having gear shifting teeth formed on its outer periphery is integrated with a boss portion having a smaller diameter than the gear diameter, and a reversely tapered spline groove is formed on the outer periphery of the boss portion. This reverse taper spline groove is formed by forging to the root of the boss part and pressing with a die matching the number of teeth, so the reverse taper spline groove can be manufactured only by the forging process, and this spline Because of the metal flow, it is strong, and the effective length of the spline can be lengthened, so the overall length of the gear can be made shorter than conventional products, which has the advantage of making the transmission more compact.

[Brief explanation of drawings]

FIG. 1 is a front view of a transmission gear according to the present invention.

FIG. 2 is a cross-sectional view of a speed change gear according to the present invention.

FIG. 3 is an explanatory diagram showing a manufacturing process.

FIG. 4 is a sectional view of a manufacturing apparatus that performs cold reverse gradient forming.

FIG. 5 is a plan view of the transmission gear of the present invention.

FIG. 6 is a plan view of the lower mold.

FIG. 7 is a front view showing a part of the lower mold.

FIG. 8 is an explanatory diagram of a die.

[Explanation of symbols]

1 Gear 2 Helical teeth 3 Boss part 4 Spline groove WHW Material 11 Upper mold 13 Lower mold 17 Case 18 Flange 21 Cam 22 pin 23 Die

Claims (1)

[Claims] Claim 1: A large number of dies corresponding to the number of teeth of a gear material formed by forging spline teeth parallel to the gear are slidable toward the axis of the gear and are fitted and supported in a lower mold, A cam that is pushed down by the lowering of the upper mold that faces the lower mold is supported so as to be able to slide vertically in a case provided on the lower mold mounting base, and each cam that comes into contact with the rear end of each die is A transmission gear characterized in that the die abutting surface is an inclined surface so that the die moves in the direction of the gear axis when the cam is pressed down, and the spline teeth parallel to the gear axis are shaped into a reverse taper shape. Manufacturing equipment.