GB1453657A - Powered strap tensioning and severing tool - Google Patents

Abstract

1453657 Strap-tensioning tool PANDUIT CORP 20 Aug 1974 [17 Sept 1973] 36517/74 Heading F2G A strap-tensioning and severing apparatus comprises a housing; movable strop gripping jaws 24, 27 attached to one end of tensioning rod 22; a strap cutting blade 32 on one end of lever 33 having centre pivot 34 supported by the housing; a compressed air motor in which plunger 23 attached to the other end of rod 22 moves longitudinally on cylinder 15 to tension a strap 26 gripped by jaws 24, 27 and cylinder 15 moves rectilinearly in the housing to operate cutting blade 32, and a spring loaded biasing mechanism 48, 49, 50, 51 acting on cylinder 15 through pivotable linkages to restrain the movement of cylinder 15 until a predetermined tension has been produced in strap 26 surrounding a bundle of wires. The predetermined pressure is set by rotating knob 50 controlling the spring pressure of the biasing mechanism and is transmitted to cylinder 15 by yoke 46 connected to pivotal arm 43 whose cam surface 42 engages cam follower 19 on one end of link plate 37 which has at its other end another cam follower 39 disposed against cylinder 15. In operation initially rod 22 is fully extended holding spring loaded jaw 24 open against one end of the housing and the end of strap 26 is inserted between jaws 24, 27. Trigger 54 is then depressed to open valve 16 allowing air from supply line 17 to enter cylinder 15 thus forcing plunger 23 to the right in Fig. 3 and moving jaws 24, 27 from the housing end to allow spring loaded jaw 24 to grip strap 26 which is then tensioned. When the predetermined pressure on strap 26 has been reached cylinder 15 reacts against the pressure of the bias mechanism and moves to the left away from the other end of the housing and in so doing pivots link plate 37 clockwise on pivot 38 forcing actuator pin 40 on plate 37 downwards against the bottom surface of slot 36 in lever 33 which pivots about pin 38 urging blade 32 upward to cut strap 26. The strap restraining movement of rod 22 is thus eliminated and plunger 23 moves to the left in cylinder 15 and a return force is exerted on plate 37 and on cylinder 15 which returns to its original position against the housing end. With trigger 54 still depressed rod 22 moves to a fully retracted position in which dog 28 on jaw 24 is held against wall 35a of channel 35 in the housing such that teeth 25 on jaw 24 are disengaged from the cut end of strap 26. On releasing trigger 54, valve 16 closes and air is slowly forced out of cylinder 15 around valve 16 as plunger 23 is urged to the left by return spring 56. In another embodiment the air operated motor is replaced by an electric motor and the air valve is replaced by a reversing switch.