| 摘要 |
1,075,306. Sliding clasp fasteners. SCOVILL MANUFACTURING CO. Nov. 2, 1965 [Nov. 23, 1964], No. 46417/65. Heading E2S. A sliding clasp fastener comprises a pair of stringers each of which comprises a tape 40 mounting a flattened coil 11 or 12, each coil being in the form of a plastics filament, with spaced convolutions, each convolution having a head end 13 adapted to interlock between a pair of convolutions of the mating coil, and a heel end 14 of rounded shape transversely of the fastener, a slider having front and back wings 16, 17, a neck uniting the wings at one end, uninterrupted guide flanges at the lateral edges of at least one of the wings which guide flanges ride over the heel ends of the coils; the wings, neck and flanges forming a slider channel with a pair of divergent upper branches joining a single lower branch, a pull tab 21 having spaced apart arms, pivotally mounted on the front wing, the front wing having apertures 26, 27 on opposite sides of the pull tab pivotal mounting, the outer edges of the apertures being substantially in alignment with the inner surfaces of the guide flanges at the junction of the channel branches, and a pair of slider locking cams 28, 29 projecting inwardly from the arms along the side edges of the pull tab, the cams extending through the apertures into the slider channel when the pull tab is swung down into a locking position, the cams when in locking positions being supported against outward lateral deformation by the flanges, each of the cams having a thick and deep portion in the region of the pivotal axis, the inner and opposed sides of the cams being relieved both vertically and horizontally of the pull tab so that each cam is generally tapering in both directions away from the thick and deep portion, whereby in locking positions the cams will wedge over the heel ends of a plurality of coil convolutions, the thick and deep portions 32 of the cams serving to force the pull tab into locking position when a tearing stress is applied to the fastener in the region of the slider after initial engagement of such portions with one or more coil convolutions. In use, the coil convolutions adjacent the slider neck are forced laterally inwardly to a sufficient extent to cause jamming of the head end of one of the coil convolutions under the neck of the slider. The portions of the coil engaging surfaces of the cams are irregular or roughened to assist the cams being selfpropelled into locking position once they have made initial contact with the fastening elements. In a modification a second pull tab similar to that on the front wing is mounted on the back wing and the back wing is apertured like the front wing. |
