Patent GB-591453-A (GB)
Title: Manufacture of slide fasteners
IPC: B21D53/50
Filed: 1944-03-31
Abstract: 591,453. Sliding-clasp fasteners. RABINOWITZ, L. M. March 31, 1944, No. 6026. [Class 44] A machine for making slide fasteners comprises co-operating stationary and vertically reciprocable cutting dies 25, 27, Figs. 4 and 6, respectively associated with horizontally moving, shaping and clamping dies 45, 46 which from an intermittently advancing strip of preformed wire, sever fastener elements and clamp them to a beaded tape advanced in step by step movement. The main feature of the invention resides in the means for locking the vertically reciprocable die 27 so that it contacts the wire strip at intervals to provide blank spaces between adjacent groups of elements on the tape. The wire strip s, Figs. 4 and 6, is previously formed with humps 101 which eventually form the co-operating male and female elements of the fastener and also with side undulations 103A. The cutting dies 25, 27 are shaped to fit the humps and undulations. The dies 45, 46, Fig. 6, after having clamped an element 105 to the tape t are withdrawn. The tape t is raised and simultaneously die 27 is lifted permitting a spring-operated buffer block 29 to raise the strip s which is advanced against the previously severed fastener element 104, which is moved against and clamped on the tape t at the same time that the die 27 descends to cut the next intermediately formed element from the strip s by means of cooperating parts of the dies 25 and 27. The dies 45, 46 have lower opposed ends 45b, 46b which initially clamp the wings 106 of the elements to the tape and upper opposed ends 45a, 46a which finally form and swage the undtilations 103A into the wings 106. At each operation there may be more than one or no intermediate fastener element 104 between the cutting dies 25, 27 and the dies 45, 46. The power for the various operations is delivered by a pulley 113, Fig. 1, and shafts 24, 42 and 51. The strip s is advanced by a presser-foot 12, Fig. 4, pivoted at 14 on a slide 16. A contact plate 10 on the presser-foot is pressed into engagement with the strip by a spring 20a. The slide 16 is advanced by a cam 19 on the shaft 24 and returned by a spring 20. The die 27 is operated by a block 28, which is adapted to be depressed by a lever 38 and a cam 41 on the shaft 42. A spring 36 returns the block and die and a spring 33 between the block and the die biases the latter towards the strip. The dies 45, 46 are moved towards one another by slides 43, 44 operated by cams 49, 50 on the shafts 42, 51. The tape t passes over a drum 54 which is rotated to feed the tape through the machine by a toothed wheel 56 actuated by a pawl 57 pivoted on a slide 60. This slide is operated by a face cam 64 on the shaft 42. The correct position and tension of the tape is maintained by a spring-pressed shoe 68 cooperating with guides beneath the dies 45, 46. One guide is fixed and the other pressed against the tape by an adjustable spring. The arrest of the tape t by the die 27 to produce blank spaces between groups of fastener elements and thus fasteners of the desired length is effected by moving a lever 82, Figs. 1 and 7, into engagement with a striker-screw 38a on the lever 38, thus holding the die 27 in its lower position to clamp the strip s against the buffer block 29. The presser-foot 12 meanwhile glides over the strip. The lever 82 is connected by a turnbuckle 84a to a bell-crank 86, 88 having a roller 89 adapted to ride on a chain 90 mounted on a sprocket 95 and another adjustably mounted sprocket. The sprocket 95 is driven by an extension 51a of the shaft 51. The chain carries camming elements 100 adapted to engage the roller 89 and operate the bell-crank mechanism and arrest the die 27, the number of camming elements determines the length of the gap on the tape. The length of the slide fasteners may be varied by using chains of different lengths,