JPS6342164Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a belt sprocket suitable for using a belt in place of a conventional chain to drive the rear wheels of a two-wheeled motor vehicle.

(Prior Art) In a conventional sprocket, an annular stepped portion is provided on the outer periphery of the rim adjacent to the teeth of the sprocket, which has teeth that mesh with the timing belt on the outer periphery of the rim.
In order to fit the annular side plate into this stepped portion and fix the side plate, the entire inner peripheral edge of the rim is widened and caulked relative to the entire inner peripheral edge of the side plate. However, in this case, vibrations and shocks during driving caused rattling, and when the side plate began to rotate relative to the rim, both parts would wear out and there was a risk that the side plate would come off. As a countermeasure to this problem, methods of welding the side plate to the rim or screwing it together may be considered, but both of these methods increase the number of processing steps, and the problem of loosening cannot be solved, especially in the case of the screwing method.

(Purpose of the invention) The purpose of the invention is to prevent the side plate for preventing the belt from coming off from rattling or falling off.

(Structure of the invention) The invention has teeth 5 that mesh with the belt on the outer periphery of the rim 4.
The sprocket 1 has an annular step 6 on both end edges of the rim outer periphery adjacent to the teeth 5, and the center hole fits into the step 6, and the radial width is slightly larger than the tooth height and wider than the tooth 5. An annular side plate 7 whose large diameter outer circumference tapers outward in the axial direction, a taper formed on the inner surface 8 of the hole that widens toward the rim end edge, and a plurality of equally spaced inner circumferential edges of the side plate 7. a caulked portion in which the inner circumferential edge of the rim 4 is partially expanded outward in the radial direction only at the location;
This belt sprocket is characterized in that the joint between the side plate 7 and the rim 4 in the caulked portion protrudes radially outward in a substantially polygonal shape relative to other joints.

(Example) Fig. 1 is a front partial view of the sprocket according to the present invention, Fig. 2 is a cross-sectional view of Fig. 1, and Fig. 3 is a partially enlarged view of Fig. 2. The inner sprocket 1 is provided with an internal spline 3 at the center of the hub 2, and the rim 4 is integrally provided with teeth 5 on the outer periphery that mesh with the belt, and is a forged product of carbon steel (for example, S45c). As is clear from FIG. 2, an annular step 6 is provided on the outer periphery of the rim 4 adjacent to both ends of the teeth 5, into which an annular side plate 7 made of sheet metal is press-fitted. The inner surface 8 (FIG. 3) of the central hole in the plate 7 has a taper that widens as it moves away from the teeth 5, so that the center line 0-
The angle of inclination α1 relative to 0 is set to, for example, 5°. Therefore, when the side plate 7 is fitted into the annular step 6 shown by the two-dot chain line in FIG. 3, a gap with a wedge-shaped cross section is formed between the step 6 and the inner surface 8 of the side plate. A tapered mold 9 having protrusions at multiple locations on the outer periphery to eliminate this gap at multiple portions equally spaced in the circumferential direction and further protrude outward in the radial direction.
is pressed against the inner circumferential edge of the rim 4 to form caulked portions 10 at equal intervals on the inner circumference, and on the outside of the caulked portions 10, the rim material of the annular stepped portion 6 is pressed against the inner surface 8 (inner surface) of the side plate 7. (periphery) to apply an outward load P to the side plate 7.
That is, at the caulked portion 10, the inner peripheral edge of the rim 4 is deformed as shown by the solid line from the shape before caulking shown by the two-dot chain line in FIG. A caulking force (load P) is applied to push the inner surface 8 of the side plate 7 outward at that portion 10. Type 9
The inclination angle (jig angle) α2 of the tapered surface is, for example, 30°,
The circumferential length L1 (FIG. 1) of the caulked portions 10 is, for example, 12 mm, and such caulked portions 10 are provided at 12 equally spaced locations. In order to form the caulked portion 10, a pair of molds 9, 9 (FIG. 2) and a pair of holders 11, 11 for positioning the side plates 7, 7 on both end surfaces of the teeth 5 are employed. . Then, the sprocket 1 and one side plate 7 are placed on one mold 9 and the holder 11, and after the other side plate 7 is fitted in a predetermined position, the other holder 1 is placed.
After holding the side plates 7, 7 in a predetermined position using 1, the other mold 9 is pressed to form the mold 9 shown in FIGS. 2 and 3.
Caulk part 1 by pressing down to the position shown in the figure.
0 is formed.

When the crimping process is completed, as described above, the inner peripheral edge of the rim 4 at the crimped portion 10 projects radially outward, applying a load in the direction of the arrow to the inner surface 8 of the side plate 7. Since the die 9 does not contact the inner peripheral edge of the rim other than the crimped portion 10, the side plate 7
The inner surface 8 of the side plate is pressed radially outward at twelve equally spaced points, and as a result, the inner surface 8 of the side plate is substantially deformed into a dodecagon, the material of the rim 4 is crimped at each apex of the dodecagon, and the material of the inner surface 8 of the side plate is also partially plastically deformed to form the rim 4
It mechanically bonds to the material.

(Effect of the invention) As explained above, in this invention, the rim 4
The sprocket 1 has an annular step 6 on both end edges of the rim outer periphery adjacent to the teeth 5 of the sprocket 1, which has teeth 5 on the outer periphery of the rim, and a hole in the center fits into the step 6, and the radial width is the same as that of the teeth. an annular side plate 7 whose outer circumferential portion is slightly larger than the height and has a larger diameter than the teeth 5 and has a taper that opens outward in the axial direction; a taper formed on the inner surface 8 of the hole that widens toward the rim edge side; The inner circumferential edge of the rim 4 is partially expanded outward in the radial direction at a plurality of equally spaced locations on the inner circumferential edge of the plate 7 to be caulked, and the joint between the side plate 7 and the rim 4 at the caulked portion is different from the caulked portion. Since the side plate protrudes outward in the radial direction in a substantially polygonal shape from the joint portion, the side plate inner surface 8 protrudes in the direction of arrow P in FIG. Since there is an inclination angle α1 in the part other than the caulked part 10, a wedge-shaped gap shown in FIG. stay in position,
A side portion between the vertices of the polygon is formed. Therefore, only a plurality of equally spaced locations on the inner surface 8 of the side plate protrude outward in the radial direction while being joined to the material of the rim 4, and the other portions do not protrude, thereby improving the anti-rotation function. That is, when a rotational torque is applied to the side plate 7 itself, the side portions of the inner surface 8 at a plurality of locations that do not project outward in the radial direction cross the joint of the annular step portion 6 that projects outward in the radial direction. become unable to cross,
The substantially polygonal inner surface 8 is fitted into the substantially polygonal annular stepped portion 6, and reliable rotation prevention is achieved. Since the taper with the inclination angle α1 is provided on the inner surface 8, not only is it possible to prevent the side plate 7 from coming off in the axial direction when the caulking portion 10 is formed, but this also works in conjunction with providing the caulking portion 10 partially. Then, leaving a gap between the inner surface 8 and the annular step 6,
This has the advantage of effectively preventing the inner surface 8 from protruding outward in the radial direction at the sides of the polygon, thereby making it possible to finish the polygon in a rounded shape.

Also, since the outer circumferential portion of the side plate 7 has a taper that opens outward in the axial direction, if the caulked portions 10 are formed at a plurality of equally spaced locations, the side plate 7 at the radially outer portion of the caulked portions 10 will be as shown in FIG. It extends outward in the radial direction as shown by the two-dot chain line 7a. As a result, the inner surface of the side plate facing the belt becomes partially corrugated with an overhanging portion 7a, and the overhanging portion 7a
makes contact with the side surface of the belt. However, the overhang 7
A caulking portion 10 is provided behind the center side of a to firmly connect the side plate 7 and the rim 4, so that the vibration impact received from the belt at the overhanging portion 7a is effectively supported by the caulking portion 10. , the effect of preventing the side plate 7 from rattling or falling off is enhanced.

Further, according to the present invention, the caulking operation using the mold 9 is only required once; for example, in the embodiments shown in FIGS. 1 to 3, the rim 4
By partially expanding the inner peripheral edge of the side plate 7 and caulking it to the inner surface 8 of the side plate 7, the inner surface of the side plate is deformed into a substantially polygonal shape, and the side plate 7 can be prevented from slipping out and rotated at the same time. Therefore, costs can be reduced by reducing the number of processing steps. In addition, in the present invention, since the structure is not such that the material of the rim 4 is inserted into the recessed part of the inner peripheral edge of the side plate 7 to prevent rotation, the shape of the joint between the rim 4 and the side plate 7 is simplified, and each material It becomes easier to manufacture, and costs can be reduced from this aspect as well.

[Brief explanation of drawings]

FIG. 1 is a partial front view of a sprocket according to the present invention, FIG. 2 is a cross-sectional view taken from FIG. 1, and FIG. 3 is a partially enlarged view of FIG. 2. 1... Sprocket,
4... Rim, 5... Teeth, 6... Annular step, 7...
Side plate, 10... caulking part.

Claims (1)

[Scope of utility model registration request] The sprocket 1 has teeth 5 on the outer periphery of the rim 4 that engage with the belt, and has an annular step 6 on both end edges of the rim outer periphery adjacent to the teeth 5, and a hole in the center fits into the step 6 and has a width in the radial direction. an annular side plate 7 whose outer circumference is slightly larger than the tooth height and has a larger diameter than the teeth 5 and has a taper that opens outward in the axial direction; and a taper formed on the inner surface 8 of the hole that widens toward the rim edge side. , a caulked portion in which the inner circumferential edge of the rim 4 is partially expanded radially outward only at a plurality of equally spaced locations on the inner circumferential edge of the side plate 7, and a joint portion between the side plate 7 and the rim 4 at the caulked portion. A sprocket for a belt, characterized in that the sprocket protrudes outward in the radial direction from other joints in a substantially polygonal shape.