GB1235116A - Tensioning apparatus - Google Patents

Abstract

1,235,116. Package binding machine; tensioning. POWER INDUSTRIES Ltd. 15 Aug., 1968 [16 Aug., 1967], No. 37690/67. Heading B8C. A tensioning device in a package binding machine comprises a primary device to draw a loop of tape on to a package and apply an initial tension thereto and a secondary device to apply the final tension, the secondary device operating through a limited stroke but may repeat its tensioning stroke a sufficient number of times to obtain the required tension, irrespective of the tape extension. As shown in Fig. 1, the primary device 11 comprises endless belt 70, tensioned by jockey pulleys 72, driven from a reversible motor M (not shown) through drive pulley 71 and also passing round pulley wheels 69, and a roller 67 as shown. Roller 67 and pulleys 69 are mounted between upstanding walls 68 of U-shaped bracket 63 which is carried by piston-rods 61 of pneumatic cylinders ET forming the secondary device. A tensioning gripper 75 is pivoted on bracket 63 and urged in a clockwise direction by spring 76 causing adjustable jack screw 78 to abut member 79 maintaining a clearance between the base 77 of the gripper and bracket 63. From the position of Fig. 1, binding tape, e.g. of polypropylene, is fed by device 11 through bracket 63 between belt 70 and pulley 67, under gripper 75, through member 79, throughan aperture 15a in a gripper 15, over a nose-plate 18, between a gripper 19 and the nose-plate 18, around the package either manually or automatically, beneath gripper 15 and again over the nose-plate 18 to form a loop having overlapping ends. Gripper 15 is then actuated to grip the tape by a trip switch which also reverses motor M to apply the initial tension to the tape. When the desired tension is reached, the torque on the motor M is opposed thereby causing the body of the motor M to twist which operates a switch to actuate the secondary tension device. Piston-rods 61 are retracted thereby causing gripper 75 to grip the tape and the final tension is applied thereby. Gripper 19 is closed on to the tape against nose-plate 18 while cylinders ET return to the position of Fig. 1, slack tape being released. A limit valve (80, Fig. 2, not shown) actuates gripper 19 if the desired final tension is not achieved in one stroke of cylinders ET. The overlapping ends of the tape are friction-welded together and severed from the tape supply.