JPH0771566A - Gear and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a gear in which the effective lengths of splines are lengthened, and the strength is secured and the accuracy of the splines has been enhanced. CONSTITUTION:Splines 3 provided with chamfers 2 are integrally provided on the outer circumferential surface of a boss 1 by means of plastic deformation, and the splines are again formed by means of coining for enhancing the accuracy of the splines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear used for a transmission and the like, which is formed by plastic working, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a spline of a gear used in a transmission or the like and a chamfer on the end surface of the spline are formed by machining, so that a clearance for a cutting tool is required.

Therefore, there is a problem that the effective length of the spline is restricted.

Further, in order to shorten the total length of the gear, the boss and the spline are separately manufactured with high precision, and the press-fitting integration and the fitting portion are fixed by welding, so that the material yield is low and The processing cost increased significantly, and there was concern about the strength of the fixed joint.

Further, since the spline is formed by machining, there is a problem that the mechanical strength is remarkably lowered by the fiber flow (the fiber direction of the material is cut).

Therefore, the present invention is to solve the above-mentioned various problems by forming by plastic working.

[0007]

In order to solve the above-mentioned problems, the present invention forms a boss and a spline with a chamfer provided on the outer periphery of the boss by plastic deformation means, and at the same time by coining means. The gear that re-molds the spline is adopted.

In addition, after the heated billet is upset and then the rough forming step is performed to form a spline forming boss, the forming step is performed to form a chamfered spline for the spline forming allowance of the boss, and then the boss is formed. The method of manufacturing a gear is characterized in that the spline is molded again by a coining process before the temperature is lowered.

Further, a boss for spline molding is formed in the upsetting process of hot, warm, and cold working of the billet, and then in a rough forming process. After forming a straight spline, and then subjecting the billet material to heat treatment such as normalization and annealing and surface scale removal treatment, if necessary, press the molding tool against the straight spline to form a back taper spline. A gear manufacturing method characterized by the above is adopted.

[0010]

Since the boss having the spline with the chamfer is formed by the plastic deformation means, the fiber flow is generated along the tooth profile and the effective length of the spline can be made longer as compared with the machining. Since the boss and the spline are integrated, the yield and strength of the material are improved and the fixing work by welding becomes unnecessary.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) As shown in FIG. 6, for example, a gear A shown in a transmission has a boss 1 and a spline 3 with a chamfer 2 provided on the outer periphery of the boss 1 by a plastic deformation means. Forming and coining means (printing pressure processing)
Thus, the spline 3 is molded again to improve accuracy.

(Second Embodiment) As shown in FIG. 1, a billet 21 cut into a required volume and shape is heated in a heating step to a temperature suitable for warm forging or hot forging.

Next, the heated billet 21 is formed into a first blank 22 having a gear shape close to that shown in FIG. 2 by an upsetting process, and this is further subjected to a rough forming process to further form a gear shape as shown in FIG. A second blank 23 (having a shape having a boss 1 and a spline molding allowance 24 on the outer periphery of the boss 1) is formed.

After this, the second blank 23 is formed by a forming process, and the spline 3 with the chamfer 2 is formed on the spline forming margin 24 as shown in FIG.

Of course, the boss 1 is also molded from the shape shown in FIG. 3 into a predetermined shape as shown in FIG.

As shown in FIG. 4, a molded gear A
When the inner diameter of the boss 1 is the through hole 25, the through hole 25 is formed in the piercing process (26 in FIG. 5 is a plate scrap).

Therefore, before the temperature of the molded gear A is lowered, the spline 3 is molded again by the coining process to obtain the gear A with improved accuracy as shown in FIG.

(Third Embodiment) A billet 31 shown in FIG.
By the upsetting process of hot working, warm working or cold working, the first blank 32 having a gear shape close to that shown in FIG.
And then a second blank 33 (having a boss 34 and a spline molding allowance 35 on the outer periphery of the boss 34) closer to the gear shape as shown in FIG. 9 is formed by a rough forming process. .

After that, the second blank 33 is formed by a forming process, and as shown in FIG. 10, a straight spline 37 with a chamfer 36 is formed on the spline forming margin 35.

The above-mentioned molding includes hot, warm, and cold.

Of course, the boss 34 is also formed into a predetermined shape.

Depending on the material of the blank, if necessary, heat treatment such as normalization and annealing and a shot blasting process remove the scale on the surface, and then the blank is subjected to a lubricant adhesion treatment.

A back taper spline 39 as shown in FIGS. 13 and 14 is formed on the straight spline 37 of the formed gear A after the above processing by using a forming tool 38.

The above molding tool 38 is shown in FIGS.
First, as shown in FIG.
To place.

At this time, the same number of molding dies 38 as the straight splines 37 of the molding gear A arranged on the entire inner circumference of the ring holder 43 of the lower mold 41 are used in the straight spline 3
Mesh with 7.

While lowering the upper die 44 arranged above the lower die 41, the punch 45 of the upper die 44 presses the upper surface of the molding gear A and the lower surface of the bush ring 46 of the upper die 44. And the upper surfaces of the respective molding tools 38 are brought into contact with each other to press the respective molding tools 38 downward.

Then, the ring holder 43 and each molding tool 3
8 by the tapered surface portion 47 of the contact surface with
Straight spline 3 while moving the
7 is molded into a back taper spline 39.

When the straight spline of the molding gear A has a missing tooth, the molding tools are also arranged so as to match the missing tooth (not shown).

[0030]

[Effect] Since the gear of the present invention is constructed and manufactured as described above, fiber flow is generated along the tooth profile.

For this reason, it is possible to eliminate the inconvenience of cutting the fiber flow and lowering the strength as in machining.

Further, since the spline is formed on the boss by plastic deformation, the effective length of the spline becomes longer than that by machining.

Further, since the spline is integrally formed on the outer circumference of the boss, the yield and strength of the material are improved, and
It is possible to eliminate the inconvenience of strength and the inconvenience that the processing cost remarkably increases due to the integration of separate parts by welding.

Further, since the spline formed by plastic deformation is formed again by using the coining means and the forming tool, the accuracy is remarkably improved.

Since the upsetting step is adopted in the cold working of the spline forming, the surplus thickness is less generated and the effective length of the spline is longer than that of the Shigoki method.

[Brief description of drawings]

FIG. 1 is a perspective view showing a billet according to a second embodiment of the present invention.

FIG. 2 is a perspective view of a first blank.

FIG. 3 is a perspective view of a second blank.

FIG. 4 is a perspective view of a spline formed on a second blank.

FIG. 5 is a perspective view in which a through hole is formed.

FIG. 6 is a perspective view in which the spline is reshaped by the coining process.

FIG. 7 is a perspective view showing a billet according to a third embodiment.

FIG. 8 is a perspective view of a first blank.

FIG. 9 is a perspective view of a second blank.

FIG. 10 is a perspective view of a straight spline formed.

FIG. 11 is a plan view of a forming tool in which a straight spline is a back taper spline.

FIG. 12 is a vertical sectional front view of the same.

FIG. 13 is a perspective view of a gear having a back taper spline.

FIG. 14 is an enlarged perspective view showing the main part of the above.

[Explanation of symbols]

 A gear 1 boss 2 chamfer 3 spline 21 billet 22 first blank 23 second blank 24 spline molding allowance 25 through hole 31 billet 32 first blank 33 second blank 34 boss 35 spline molding allowance 36 chamfer 37 straight spline 38 forming Mold tool 39 Back taper spline

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29D 15/00 2126-4F

Claims (3)

[Claims] 1. A gear in which a boss and a spline with a chamfer provided on the outer periphery of the boss are formed by plastic deformation means, and the spline is reshaped by coining means. 2. A heated billet is upset and then a rough forming step is performed to form a spline forming allowance boss, and then a forming process is performed to form a chamfered spline for the spline forming allowance of the boss. A method for manufacturing a gear, wherein the spline is reshaped by a coining step before the temperature is lowered. 3. A billet is formed into a boss as a spline molding allowance in a hot, warm, cold working upsetting process and then in a rough forming process, and then the spline forming allowance is provided with a chamfer. After forming a straight spline, and then subjecting the billet material to heat treatment such as normalization and annealing and surface scale removal treatment, if necessary, a molding tool is pressed against the straight spline to form a back taper spline. A method for manufacturing a gear, which is characterized by the above.