JPS6234036Y2 - - Google Patents

Description

[Detailed description of the invention] Conventionally, this type of mainspring has its outer end 6 folded in half and a small tube-shaped locking protrusion 7 provided at the bent end, as shown in Fig. 4. A structure with a similar structure is known, but this structure requires two to three presses, so there is a limit to cost reduction, and when loading the whole thing into a mainspring drum, It is necessary to hold the outer end part 6 with your fingers so that it does not spread into two forks as shown by the phantom lines in the same figure and interfere with the winding process, which causes problems such as poor loading workability. The money was warm.

The purpose of the present invention is to eliminate such defects, and the entire outer end of the mainspring body is curved into a shallow gutter shape, and the same part is bent into the shape of Mt. Fuji with both long skirts. The gist is that a halved cylindrical protrusion for locking into a locking groove provided on the inner circumferential surface of the mainspring drum is provided at the top of this bent portion.

In the embodiment shown in the figure, the entire outer end 2 of the main spring body 1 is bent into a shallow gutter shape, and the same part 2 is bent into a Mt. A halved cylindrical protrusion 5 for locking into a locking groove 4 provided on the inner circumferential surface of the cylinder is provided.

Since the present invention has the above-mentioned structure, the bending of the outer end can be easily done by one press process, unlike the above-mentioned known method, and this can lead to a significant cost reduction. Furthermore, when loading the entire spring into the mainspring drum, the outer side of the protrusion naturally extends in the opposite direction to the winding direction, as shown by the imaginary line in Figure 1, and almost the rest of the mainspring Since the direction is the same as that of the protruding part, the same part does not interfere with the rolling-in unlike the above-mentioned known parts, and therefore special operations such as extending the outer part of the protruding part with fingers are not possible. It has the advantage that the same winding work can be easily done without the need for it. Since the entire part is curved into a shallow hem shape, the waist of this part is strengthened and the elastic force in the inward and outward directions increases. This has the effect of strengthening the engagement force with the groove and reliably preventing the risk of the part coming off the locking groove during operation and causing the mainspring drum to spin idly.

[Brief explanation of the drawing]

The figures show an embodiment of the mainspring of the present invention, in which Fig. 1 is an overall side view, Fig. 2 is a perspective view showing the state loaded on the drum, and Fig. 3 is Fig. 2 A-A.
A sectional view taken along the line, and FIG. 4 is a perspective view showing the conventional one. DESCRIPTION OF SYMBOLS 1... Spring main body, 2, 6... Outer end, 3... Spring drum, 4... Concave groove, 5, 7... Projection.

Claims (1)

[Scope of utility model registration request] The entire outer end of the mainspring main body is curved into a shallow gutter shape, and the same part is bent into the shape of Mt. Fuji with long skirts, and a locking recess is provided on the inner circumferential surface of the mainspring drum at the top of this bent part. A mainspring equipped with a halved cylindrical protrusion for locking into a groove.