| 摘要 |
<p>From a spring band (6), a first winding (18) is formed which is comprised of turns which are arranged flat on top of each other. A straight terminal portion (6A) not yet wound of the spring band is folded in the direction opposite to the flexure direction of the winding turns (18), in an arc of a circle to form a terminal arc (6B) directly connected by a continuous and progressive junction to the outer turn of the winding (18). The curvature radius of the terminal arc (6B) coincides with the radius of a winding mandrel (19) on which is wound the spring band (6) after having been subjected to a heat treatment, and in the direction opposite to the flexure direction of the turns of the first winding (18). The thus formed second winding (20) is provided to be inserted as a driving spring into a spring casing, the end (7) of the spring band (6) situated outside on the second winding (20) being connected to the circumferential wall of the spring casing and the terminal arc (6B) now arranged inside being connected to a core rotating in the spring casing and of which the radius coincides also with the curvature radius of the terminal arc (6B). The spring core may be coupled to a winder drum, for example for a safety belt. The driving spring thus obtained is differentiated by a proportionally high initial torsion moment, as soon as a small member of revolutions of the spring core is reached.</p> |
