JPS623696B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a gear with a boss in which a gear having a boss on one end surface and a shaft hole in the shaft center is manufactured by press working with high productivity.

There have been many ideas for manufacturing gears through plastic deformation, but they have only been produced as prototypes and have not been put to practical use. Gears with bosses are particularly difficult to manufacture; generally, the gear blank is manufactured by forging, and the tooth profile is obtained by machining.

The present invention provides a practical method for manufacturing bossed gears by combining special extrusion using a mandrel (method for manufacturing flanged hollow products), opposed die shearing, burring, or machining. It is something.

The figure will be explained in detail below.

Figures 1 and 2 show the principle of an apparatus for manufacturing flanged hollow products. The illustrated products are a plug (blind hole) shown in FIG. 1 and a gear blank (through hole) shown in FIG. 2, each having a simple cylindrical shape.

The punch a has an outer diameter equal to the outer diameter of the product flange part g, and a through hole e has an inner diameter equal to the outer diameter of the product hollow part h.
have. A restraint ring b is slidably fitted around the outer periphery of the punch a, and a pressure plate c is placed at the bottom. A mandrel d having an outer diameter equal to the inner diameter of the product inner hole i is slidably held at the center of the pressure plate c. Then, in a closed cavity j having an inner diameter equal to the outer diameter of the product flange part g formed between the punch a, the pressure plate c, and the restraining ring b, a workpiece f having an outer diameter approximately equal to or slightly smaller than the outer diameter of the product flange part g is placed. (Figure 1 A).

In this way, the mandrel d is pushed out into the cavity j while the workpiece f is clamped and pressed by the punch a and the pressure plate c. The outer periphery of the workpiece f is compression-molded to the thickness of the product flange g, and the inwardly extruded material forms a depression in the center of the lower surface and rises and flows into the through hole e of the puncher a, but By protruding d, while assisting the flow, the hollow is shaped to form the inner hole i of the product, the thickness of the hollow part h of the product is made uniform, the outer shape is adjusted, and flanges are attached all at once. A hollow product is formed (Figure 1 B).

By attaching a die hole k corresponding to the mandrel d to the tail end of the through hole e of the punch a and punching out the top h of the cap-shaped protrusion, the product inner hole i can be made into a through hole ( Figure 2).

In the case of the above manufacturing method, the workpiece used is one that has been previously processed into the product flange external shape or a slightly smaller shape. Further, the metal fitting used as a tool may be a die-type metal fitting made by integrating the restraining ring b and the pressure plate c. Furthermore, the arrangement of the mandrel d and the through hole e remains the same even if they are provided on metal fittings on opposite sides. Holding the mandrel d on the punch a side has a larger pressure receiving area of the punch a, which is advantageous in terms of tool life.

FIG. 3 shows an example of an apparatus for carrying out the method of the invention.

The punch fitting 1 has a rough gear shape with a small cutting allowance added to the tooth surface of the product gear, and a mandrel 2 having an outer diameter equal to the inner diameter of the product shaft hole 11 can be freely slid on the shaft center. to hold. Dice fittings 3
has a die hole 4 with a bottom (bottom surface 5) having an inner shape of a rough gear shape corresponding to the outer shape of the punch fitting 1, and a through hole with an inner shape equal to the outer diameter of the product boss part 12 in the bottom surface 5. 6 opens. An ejector 7 is slidably held in the through hole 6, and a die hole 8 is provided at the tip of the ejector 7 to correspond to the tip of the mandrel 2. A sub-ejector 9 is further inserted through the axis of the ejector 7.

The workpiece 14 has a diameter equal to or slightly smaller than the diameter of the tooth bottom of the rough gear shape, and is supplied into the die hole 4 .

In the manufacturing process, as shown in FIG. 4 and subsequent figures, the punch fitting 1 and the die fitting 3 are pressurized and the mandrel 2 is ejected at the same time.

First, the workpiece 14 is squeezed between the punch fitting 1, the die hole bottom 5, the ejector 7 and the sub-ejector 9 set at the boss top forming position, and its peripheral portion is crushed and flows outward. A part of the material filled in the teeth is formed into a rough gear shape, and at the same time, the material flowing inward rises into the through hole 6 while forming a depression in the center of the upper surface of the workpiece 14. The flow is assisted by the protrusion of the mandrel 2, fills the through hole 5, and is formed into the outer shape of the product boss portion 12 (FIG. 4).

Subsequently, by protruding the mandrel 2, the top of the boss portion 12 is punched out between the die hole 8 and the product through-hole 11 is formed (FIG. 5).

Next, the metal fittings 1, 3 and the mandrel 2 are restored, the ejector 7 is pushed out and the rough product 10 is extracted (Fig. 6), the sub-ejector 9 is further pushed out and the scrap 15 is extracted (Fig. 7), and the process is completed. do.

In the rough product 10, the tooth portion 13 is larger than the required product by the amount of cutting allowance, and a "sink mark" 16 as shown in FIG. 8 may occur on the bottom of the tooth. This machining allowance is then sheared with opposing dies to create a regular tooth profile.

As shown in FIGS. 9 and 10, the facing die shearing method uses a flat die 17 that has the same die hole as the inner contour of the product shape (in this case, a tooth shape), and A die 18 with a protrusion 19 is placed opposite the die 18 with a protrusion 19, and the material is sandwiched between the two dies 17,
By applying pressure to the flat die 18, precision punching can be performed while removing the punching chips 21 outward from the blade angle 20 of the flat die 17 by a mechanism similar to the cutting process. If the thickness is less than the width of the protrusion 19, scraps 21
Since it becomes difficult to remove it, the knockout tool 22 is used to cut it out.

This opposing die shearing process has difficulty in machining closed curves such as gear teeth due to the removal of scraps as described above, but in the rough product 10, most of the tooth shape is left with a cutting allowance. This allows for smooth removal of scraps and allows for easy precision machining.

The teeth can also be finished by burring or machining. Similar to the opposed die shearing process, most of the tooth profile is formed and the cutting allowance is small, so the process is easy. Opposed die shearing is advantageous in that it can be processed simultaneously using the same press machine.

As described above, the present invention plastically deforms a rough gear-shaped product by extrusion processing using a mandrel, and combines this with finishing processing such as opposed die shearing processing to precisely finish the tooth part.
Overall, this is a unique method that can manufacture bossed gears with extremely high productivity, and is particularly useful for manufacturing synchronizing gears in which the side surfaces of the teeth have a chevron-shaped synchronizing tooth profile.

[Brief explanation of the drawing]

Figure 1 shows the manufacturing equipment for hollow products with flanges (blind holes), A is a vertical cross-sectional view showing the state before processing, B is a longitudinal cross-sectional view showing the state after processing is completed, and Figure 2 is the manufacturing equipment for hollow products with flanges (through holes). FIG. 3 is a vertical cross-sectional view of the apparatus used in the method of the present invention, FIGS. 4 to 7 are longitudinal cross-sectional views sequentially showing the same processing states, and FIG. FIGS. 9 and 10 are longitudinal cross-sectional views showing the principle of opposing die shearing processing. 1...Punch metal fitting, 2...Mandrel, 3...Die metal fitting, 4...Dice hole, 5...Bottom surface, 6...Through hole, 7...
Ejector, 8...Dice hole, 9...Sub-ejector,
10...Rough product, 11...Product shaft hole, 12...Boss part,
13... Rough tooth section, 14... Workpiece material, 15... Scrap.

Claims (1)

[Scope of Claims] 1. A punch-type fitting having an outer shape in the shape of a rough gear, which is slightly larger than a product gear, and a bottomed die fitting having an inner shape in the shape of a rough gear, facing each other so as to be pressurizable, A mandrel with an outer contour equal to the inner contour of the shaft hole of the product is slidably held at the axis of one of the metal fittings, and a mandrel with an inner contour equal to the outer contour of the product boss part is attached to the axis of the other metal fitting. A sub-ejector is slidably provided at the axis of the ejector that is slidably installed in the through-hole and corresponds to the end face of the mandrel, and a gear-shaped tooth bottom is provided in the die-shaped metal fitting. A workpiece with an outer diameter approximately equal to the diameter of the workpiece is accommodated, the ejector and sub-ejector are set at the boss top forming position, and the mandrel is pushed out while applying pressure with both metal fittings. During compression molding, a part of the material is pushed toward the center to create a depression on the opposite side and flow into the through hole, and at the same time, a mandrel is pushed out to shape the depression and form a hat-shaped boss. Finally, the top of the cap is engaged with the die hole to punch out the shaft hole, and the coarse gear with a boss thus manufactured is extruded from the mold by an ejector, and in the next process. A method for manufacturing a gear with a boss, characterized in that the tooth dimensions of the product gear are precisely finished by opposing die shearing, burring, or machining.