GB642839A - Improvements in method and apparatus for manufacturing slide fasteners - Google Patents

Abstract

642,839. Making sliding-clasp fastenings. SERVAL SLIDE FASTENERS, Inc. Feb. 24, 1948, No. 5461. Convention date, Nov. 1, 1940. [Classes 83 (ii) and 83 (iv)] Stamping; shearing.-A method of embossing a metal strip to form a string of connected elements for a sliding clasp fastener oomprises stamping one, or preferably a group of elements, between a pair of dies and maintaining constant the shape and the spacing of the elements by simultaneously repressing between similar dies a group of previously formed elements immediately in front of the element or group of elements being stamped. A press suitable for carrying out the invention comprises a bed-plate 44 supporting a stationary die-holder 83 and a head carrying a die-holder 48 reciprocated between guides 45 from a crankshaft 52. A known kind of strip feed device 60 is operated from the crank-shaft by linkage 64 to feed the work between the dies. The lower die holder carries a stamping die 86 with a line of upstanding projections 87 and a shearing die 91 with two groups of cutting edges 92, 93. The upper die holder carries a stamping die 68 with a line of depressions to co-operate with the projections 87 and with two groups of cutters 76, 78, the latter group being arranged to engage the work before the former group. After each operation of the press head, the strip is lifted clear of the lower dies by a spring- operated ejector rod 99 and is stripped from the upper dies by fixed members such as 106, 108 which overlie the edges of the strip. In operation, the strip is fed forward a distance equal to the length of a group of, say, four fastener elements at a time and while the portions 72a and 87a of the stamping dies are forming four new elements from the strip, the elements immediately in front are firmly pressed between the portions 72b and 87b to prevent any distortion of the previously formed elements due to a flow of metal resulting from the formation of the fresh elements. This arrangement also ensures accurate spacing of all the elements along the strip. After being stamped, the edges of the elements are cut as shown in Fig. 12 by the cutting dies 76 and 91, the other cutting die portion 78 engaging a previously cut portion of the strip and ensuring accurate spacing.