JPH03288052A - Gear for transmission - Google Patents

Abstract

PURPOSE:To improve shift feeling in gear change and rationalize a manufacturing process by forming both ridgeline of a chamber part and its borderlines against a straight part into rounded shapes, and forming the inclined faces thereof into spherical face shape curved in both directions of the ridgeline and the direction orthogonal to the ridge line by a plastic deformation means. CONSTITUTION:A tooth form part 6 is molded to provide a gear product through a cold forging process by using a forging die in which each part corresponding to each inclined face 5a of a chamber part 5 is formed into a spherical face having its center recessed with both ridgeline 5b and borderlines 5c between the chamfer part 5 and a straight part 8 formed into rounded shapes. The tooth form part 6 is further subjected to each subsequent process to become a finished product. The thus formed tooth form part 6 is plastically deformed by faithfully following the forging die shape because of the high accuracy of the forging die. Gears rub against each other while being in mutual contact at one point P, so that frictional resistance is reduced to the minimum. Gear change is thereby performed smoothly, and shift feeling is improved to much extent. Furthermore, durability becomes outstanding because of the hardened surface.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention is applicable to gear changes such as reverse idle gears, reverse gears, main gear synchronizing teeth (also referred to as clutch gears, dog gears), etc. used in manual transmissions of automobiles. This invention relates to an improvement in the shape of a chamfer (square chamfer) formed in the tooth profile of a transmission gear that is operated.

B. Prior Art The chamfer portion 5 of the conventional transmission gear is cut or ground with an end mill or the like after gear cutting with a hob or gear shaper, and the inclined surface 5a is a smooth surface as shown in FIG. 7a. Alternatively, as shown in FIG. 7C, the curved surface was curved like the peripheral surface of a cylinder with respect to either the direction of the ridge line 5b or the direction orthogonal to that direction.

C. Problems to be Solved by the Invention In the conventional transmission gear described above, when cutting the chamfer portion, burrs 13 are generated as shown in FIG. Or, as shown in FIG. 8C, the inclined surface 5a of the chamfer part 5 is not formed symmetrically, causing uneven contact due to the difference in direction.
As shown in FIG. 2, the flat remaining portion 14 of the ridge line portion 5b may cause a meshing problem.

In addition, in the synchronized mesh mechanism, Fig. 9 a, b and 1
As shown in Figures 0a and %C, by operating the change lever, the teeth 15a of the sleeve 15 first mesh with the teeth 16a of the synchro ring 16, and the rotational speed of the sleeve 15 and the rotational speed of the synchroring 16 are synchronized. Then, the teeth 15a of the sleeve 15 rub and mesh with the synchronizing teeth 11, but during this rubbing process, the teeth 15a of the sleeve 15 and the chamfer of the synchronizing teeth 11 become flat surfaces. In this case, as shown in Figure 11, there is surface contact and the contact surface becomes the entire surface F. If the chamfer is a curved surface, the contact surface becomes a linear portion as shown in Figure 12.

At this time, if the roughness of the chamfer is rough, the frictional resistance becomes large, so there is a drawback that the gear change cannot be performed smoothly and the feel is poor.

2. Means for Solving the Problems The present invention is a gear for a transmission developed as a result of intensive research in order to improve the shift feeling during gear changes and to streamline the manufacturing process. Both the ridge line and the boundary line between the chamfer part and the straight part are R-shaped, and the inclined surface of the chamfer part is
It is formed by plastic deformation means into a spherical surface shape that is curved in both the ridge direction and the direction orthogonal to the ridge direction.

E. Since the molding is performed by the action plastic deformation means, no cracks are generated in the chamfer part during molding, and the shape of the chamfer part is determined by the mold, and there is no difference in direction or flat surface remaining. In addition, the surface is much smoother than the cut surface, and the synergistic effect with the chamfer shape unique to the present invention provides a good shift feeling during gear changes.

Furthermore, durability is further improved by surface hardening.Example An example of a transmission gear according to the present invention will be described with reference to the drawings.

Figure 1 shows the reverse idle gear (including reverse gear)
1 is a cylindrical material obtained by cutting a bar material to the required length. First, this material 1 is subjected to plastic processing (in the example, hot or warm forging processing). )
Heat to the appropriate temperature. The material 1 is not limited to a cylindrical shape, but may have any shape as long as it is suitable for the formed product, and the material 1 is first crushed into a flat upset in a hot or warm forging process. product 2, and then the upset product 2 is plastically deformed into a first forged product 3 in which the tooth profile has not been formed using a forging die that does not have a tooth profile, and then a first forged product 3 in which a shaft insertion hole is punched out by piercing. 2 forged products 4
shall be. After the above-mentioned forging process is completed, the molded product that has undergone well-known annealing, shot blasting, and bonding processes is processed so that the part corresponding to the inclined surface 5a of the chamfer part 5 is connected to the ridge line 5b and the chamfer part to the straight part 8. A gear product 7 is obtained by cold forging the toothed portion 6 using a forging die in which both the boundary lines 5C are R-shaped and the center is recessed to form a spherical surface.
Further, a standard process, a bonding process, and a coining process are performed, and finally, the straight part 8 is corrected into a reverse tapered surface in which the tooth thickness widens toward the chamfer forming side to form a finished product (FIG. 2).

In the reverse idle gear formed in this way, the tooth profile portion 6 is plastically deformed faithfully to the shape of the forging die using a high-precision forging die, and the occurrence of paris is observed during the forming process of the chamfer portion 5. However, in the chamfer part 5, the left and right inclined surfaces 5a, 5a are symmetrical, there is no remaining flat surface on the ridge line part, and the surface is extremely smooth compared to cutting. 5b and the boundary line 5c between the chamfer portion and the straight portion are both rounded and the inclined surface 5a is a spherical surface, so that the shape is extremely faithfully formed to the desired shape.

In addition, since the gears rub against each other at one point P as shown in Figure 6, frictional resistance is minimized, which allows for smooth gear changes and greatly improves the shift feeling. It also has excellent durability.

In addition, in the reverse idle gear of this embodiment, all corners 9 where the ridge line of the chamfer part and the boundary line between the chamfer part and the straight part intersect are also formed in an R shape.
The gear change operation can be performed more smoothly, and by providing the straight portion 8 with a reverse taper, it is possible to prevent the gear from slipping out.

Although the above embodiment has been described with respect to a reverse idle gear, the same can be said of the synchronizing meshing teeth of a main gear provided with synchronizing meshing teeth on the boss portion.

Next, the meshing tooth 1 for synchronization is attached to such a boss portion 10.
We will explain the manufacturing process of the main gear equipped with 1.

A cylindrical material 1' obtained by cutting a bar material to the required length is heated to a temperature suitable for plastic working as described above, and in the forging process, an upset product with a bulge around the center is first produced. 2
', and then the part corresponding to the inclined surface 5a of the chamfer part 5 of the part corresponding to the meshing teeth for synchro is formed.
The ridge line 5b and the boundary line 5c between the chamfer part 5 and the straight part 8 are both R-shaped, and the forging die is formed into a spherical surface with a depression in the center, so that the tooth profile of the main gear is not formed and the synchronizer mesh is not formed. First forged product 3′ with mating teeth 11
are integrally forged, and in a deburring step, the outer pawl 13', which is the excess thickness, is removed and pierced to form a second forged product 4'.

In this step, only piercing is performed if the first forged product 3' does not have an outer hole 13'. The helical gear 12, which becomes the tooth profile of the main gear, is cut through standard, shot blasting, bonding, and coining processes, and the meshing teeth 11 for synchro are cut.
A gear product 7' is obtained by giving the straight portion 8 a reverse taper in which the tooth thickness widens toward the chamfer forming side.

If the synchronizer meshing teeth 11 are formed integrally with the main gear consisting of the helical gear 12 by forging in this way, no cracks will occur during the process of forming the chamfer portion 5, and the chamfer Inclined surface 5a of portion 5
has a spherical surface shape, and as a result, during the meshing process of the gears, the gears come into point contact and rub against each other as shown in FIG. 6, so the frictional resistance is minimized and the shift feeling can be improved.

In the drawing, the boss portion 10 has synchronizing teeth 1.
1, the main gear with synchronizing teeth 11
Although the helical gear 12 has a smaller diameter than the helical gear 12, the fourth
As shown in the figure, even if the synchronizing teeth 11 have a larger diameter than the helical gear 12, they are formed in the same manner.

Furthermore, the radius of curvature of the spherical surface on the inclined surface of the chamfer part,
The forming process by forging may be set and changed as appropriate depending on the size of the teeth, the number of teeth, etc.

G. Effect The transmission gear of the present invention has a tooth profile of a predetermined shape integrally formed by a manufacturing method that effectively utilizes plastic deformation technology, and there is no occurrence of cracks during chamfer formation, so the manufacturing process is easy. It is possible to form a highly accurate transmission gear in which the chamfer part has a specific shape, and a good shift feeling is guaranteed by using this transmission gear. Moreover, since it is formed by plastic deformation, it hardens the surface, increasing its strength and being able to withstand hard use, so its practical benefits are great.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the product forming process of a transmission gear according to the present invention, FIG. 2 is a partially enlarged perspective view of the transmission gear, and FIG. 3 is a product forming process of another transmission gear. FIG. 4 is an explanatory diagram showing another transmission gear, and FIG.
The figure is an enlarged explanatory diagram showing the shape of the meshing teeth for synchro,
Fig. 6 is an explanatory diagram showing a state in which the gears are in contact with each other, Fig. 7 a, b, c and Fig. 8 a, b, c are explanatory diagrams of the conventional example, Fig. 9 a, b, and Fig. 10 a. , b are explanatory diagrams of the operation of the synchronizing mechanism, and FIGS. 11 and 12 are explanatory diagrams showing a state in which gears in a conventional gear are in contact with each other.

Claims (1)

[Claims] Both the ridge line of the chamfer part and the boundary line between the chamfer part and the straight part are R-shaped, and the inclined surface of the chamfer part is curved in both the direction of the ridge line and the direction orthogonal to the ridge line direction. A gear for a transmission that is formed into a spherical surface shape using plastic deformation means.