JPS63112038A - Forging method for spur gear provided with flange - Google Patents

Abstract

PURPOSE:To prevent a straightening metallic die from being damaged due to application of pressure exceeding straightening pressure, by expanding a boss part in a sizing stage and simultaneously, moving the excess metal of a stock inserted and held between the upper and the lower dies, in the direction for reducing the whole shaft hole a and bulging and straightening a rough shape tooth. CONSTITUTION:A stock is heated to a temperature suitable for hot or warm forging, and it passes through an upsetting stage and formed as one body by forging so as to have a smaller rough shape tooth T1 than a necessary shape, in the outside periphery of a boss part 7 projected in the axial direction from a flange part 6. Subsequently, cold sizing for forming a finish tooth T2 of a desired shape is executed by punching a shaft hole 9 in its center, and also, putting this stock W5 into a die sinking part of a die 21, and expanding the boss part 7 from the inside diameter. By this sizing, the excess metal of the stock inserted and held between the die 21, a counter punch 25 and a punch 20 moves in the direction of the shaft hole 9, and the whole shaft hole is re duced. A stock W6 which has been brought to sizing in such a way is pushed out from the die 21 by a knockout 24.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flanged straight gear used in automatic transmissions of automobiles, etc. The straight gear is forged on the outer periphery of a boss part that protrudes from the flange part. Concerning a method of molding.

Conventional Technology A method of cold forging a spline on the outer periphery of a boss portion that projects in the axial direction from the flange portion is disclosed in Japanese Patent Application Laid-Open No. 152650/1983, in which a mold is pressed in the axial direction of the boss portion.

Problems to be Solved by the Invention The conventional forging method described above is effective in forming splines with a tooth height of 1 mm or less, but it is difficult to form gears with high tooth heights.

In other words, when trying to mold a gear with a high tooth height, the surface layer on the outer circumferential side of the boss portion is pushed toward the intersection with the flange portion by the mold edge, which not only causes shrinkage of the teeth, but also
There is a problem in that a large molding load is applied to the mold, causing the mold to crack.

Since such a forged gear with tooth shrinkage has an integral flange portion, it is impossible to straighten the teeth by pushing it through a die having a tooth profile.

In addition, in order to compress the boss part in the axial direction and correct the tooth bulge, there is no other way than to apply pressure including the flange part. occurs.

Furthermore, when a material before orthodontic treatment is formed by hot or warm forging, there is the inconvenience of having to manufacture gear electrodes in consideration of heat shrinkage of the material.

Therefore, the problem with flanged straight gears is that it is extremely difficult to forge them and correct tooth bulges.

Another way to solve the problem is to heat the material cut into a predetermined volume to a temperature suitable for hot or warm forging, and then go through an upsetting process to form a flanged straight gear into the flange part. The outer periphery of the boss part that protrudes further in the axial direction is integrally formed by forging so that it has coarse teeth smaller than the required shape, and then after the material is cooled, the boss part is enlarged from the inner diameter in a cold sizing process. Then, the rough-shaped teeth are bulged and corrected to form finished teeth with a desired shape.

The load that bulges and straightens the working teeth is not hindered by the flange, but is concentrated on the boss and directly expands the diameter of the boss from the inside to the outside, expanding the diameter of the entire boss. , fill every corner of the die tooth mold with the teeth of the material.

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

First, a material is cut as shown by the two-dot chain line in FIG. 2 so as to have a volume corresponding to the diameter, shape, etc. of the flanged straight gear to be manufactured.

This cutting material W1 is made of a steel material that is normally used for gears.

Next, this material W1 is heated to a temperature suitable for hot or warm forging.
That is, it is heated to 600°C to 1200°C.

The heated material W1 is then upset formed by forging as shown by the solid line in FIG.

Next, the upholstered material W2 is put into the die engraving part 4 of the die 2 shown in FIG. 3 and upset again to form a flat material W8. In addition, 1 in Fig. 3 is a punch. 3 is a knockout.

Next, the flat material W3 is put into the die engraving part 12 of the die 11 shown in FIG. Forged to have.

That is, by the die 11 having the tooth pattern 13 in the die-carving part 12, the counter punch 15 which is fitted into the die 11 and defines the inner peripheral surface of the boss part 7, and the knockout 14 which provides the die-carved bottom surface together with the counter punch 15. The material W3 is inserted into the formed die-scabbing space, the punch 10 is entered into the space, and the material W8 is forged in a substantially closed state. As a result, the boss portion 7 is pushed out, and rough teeth Tl are formed on the outer periphery of the boss portion.

A portion defining the inner circumferential surface of the boss portion 7 of the counter punch 15 is formed into a frustoconical wall surface 16 that tapers toward the tip of the counter punch.

In the material w4 on which the rough teeth T1 are formed, a shaft hole 9 (Fig. 5) is punched out if necessary, and a boss portion 7 is punched out after the material has cooled.
In order to make the axial length of the tooth a predetermined dimension, a step of scraping off the tooth tip surface 8 is added.

Next, after performing lubrication treatment such as bonding treatment on the raw material W5 to which the above process has been added, the raw material W5 is put into the die-scabbing part of the die 21 shown in FIG. 5, and the boss part 7 is expanded from the inner diameter. Then, cold sizing is performed to form finished teeth T2 of a desired shape.

The tooth pattern 23 of this sizing die 21 is formed to have a dimension of the desired finished tooth T2 which is larger than the rough tooth T1 of the material W5. Therefore, as shown in the left half of FIG. The coarse tooth T1 of the material W5 can be easily inserted and adapted.

The frustoconical wall surface 26 of the sizing counter punch 25 is formed to have a larger outer diameter than the inner peripheral surface of the boss portion 7 of the corresponding material W5.

Therefore, when the material W5 is pushed into the die 21 and the counter punch 25 with the punch 20, the diameter of the boss portion 12 is expanded by the wall surface 26 and spreads outward υ, as shown in FIG.
Along with this, the rough tooth T1 is also bulged and corrected to form a finished tooth T2 having a desired size and shape.

The material W6 sized in this way, that is, the straight gear with the flange portion 6, is dieed by the knockout 24! J1 is extruded, and a helical gear is cut into the flange portion 6 to complete the process.

Effects As described above, according to the present invention, the load for correcting the bulge of the teeth is not hindered by the flange portion, but is concentratedly applied to the boss portion so as to directly expand the diameter of the boss portion from the inside to the outside. Since the diameter of the entire boss portion is expanded to fill every corner of the die tooth mold with the tooth portion of the material, it is possible to bulge and correct rough teeth into finished teeth of the desired shape with a small molding load. Therefore, the rough-shaped teeth can be formed in a rough and sunken state, that is, formed smaller than the required shape, and the formation of the material becomes extremely easy without the need to consider heat shrinkage and the like.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory diagram showing tooth orthodontics. Figure 2 is a plan view of the material. Figure 3 is a cross-sectional view of the material upsetting process. FIG. 4 is a sectional view of the gear forming process. FIG. 5 is a cross-sectional view of the sizing process. (Explanation of symbols) Wl, W2. Wa, W4. W5. W6...
···· material. T1... Roughly shaped teeth. T2... Finished tooth. 6...Flange part. 7...Boss department.

Claims (1)

[Claims] The material W_1 cut into a predetermined volume is heated to a temperature suitable for hot or warm forging, and then subjected to an upsetting process to form a boss that projects a flanged straight gear in the axial direction from the flange portion 6. Roughly shaped teeth T_ smaller than the required shape on the outer periphery of part 7
1 by forging, and then the material W_5
After cooling, the diameter of the boss portion 7 is enlarged from the inner diameter in a cold sizing step to correct the bulge of the rough tooth T_1, thereby forming a finished tooth T_2 having a desired shape. Forging method.