Patent GB-1488290-A (GB)
Title: Strapping apparatus
IPC: B29C65/06
Filed: 1975-10-20
Abstract: 1488290 Seaming non-metallic sheet material SIGNODE CORP 20 Oct 1975 [21 Oct 1974] 43018/75 Heading B5K Overlapping portions 40, 41 of thermoplastic strapping tensioned around an article are joined by gripping and compressing the portions 40, 41 between opposing gripping surfaces 11, 14 of a pair of jaws 10, 13, the jaw 13 being fixed on the base 1 and the jaw 10 being attached to a vibratory end 8 of a cantilevered bar spring 5 mounted on a bracket 6 anchored to the base 1; deflecting the end 8 to store energy in the spring 5, and releasing the end 8 to effect relative oscillatory movement between the gripped portions 40, 41. In one embodiment, Figs. 1, 3, 4 and 5, a hand grip 4 extends outwardly from the base 1 for holding the tool stationary during a strapping operation. A cutter blade 12 may be provided on the surface 11. A guide 15 is provided on the base 1 for guiding strapping between the surfaces 11, 14. A gripping mechanism 16 comprises a control lever 17 pivoted on the base 1 by a pin 18 and which is connected to an arm 19 supporting a gripping surface 20 urged downwardly against the guide 15 by a spring 21. The fixed end 7 of the U-shape spring 5 is mounted on the bracket 6 at a slightly downward angle with the horizontal so that the end 8 is inclined downwardly. An operating handle 60 pivotally mounted by a pin 61 in a yoke 68 controls movement of the jaw 10 with respect to the jaw 13. A tension spring 67 maintains the pin 61 in the bottom of slots 63, 64 in the yoke 68. A lifter cam 70 and a locking cam 71, Figs. 3 and 4, are positioned on the handle 60. In operation, the tool is seated atop an article to be strapped and the handle 60 is in its start position with the cam 70 engaging a detent 79 on a pivotally-mounted lift arm 75 so that the vibratory end 8 is raised, by a portion 81, to lift the jaw 10 and to store return energy in the spring 5, Fig. 4. The portion 40 of the strapping, e.g. of nylon, polypropylene or polyester, is placed in the guide 15 and the lever 17 is depressed by the operator so that the portion 40 can be placed under the surface 20 and onward between the surfaces 11, 14. The lever 17 is released so that the surface 20 holds the portion 40 against a portion 23 of the guide 15. The strapping is passed around the article and placed in the guide 15 so that a portion 41 overlies the portion 40. The operator grasps the grip 4 to hold the tool stationary and pulls strapping to the desired tension. The portion 41 is lifted upwardly to engage an end 73, Fig. 1, of the handle 60 to move this handle upwardly until the cam 70 disengages from the detent 79 in the arm 75. This releases the end 8 to move the jaw 10 downwardly to compress the portions 40, 41. The operator releases the portion 41 and moves the handle 60 about the pin 61 so that the cam 71 engages a comer 90 of the end 8. On release, the end 8 and thus the jaw 10 oscillates with diminishing amplitude over the jaw 13 and the portion 41 slides relative to the portion 40 so that the interface regions melt. When the jaw 10 stops, the melted regions resolidify to form a joint. The blade 12 severs the portion 41 at the end of the joint, the operator pulling the portion 41 with a twisting motion against the blade 12. There is no outwardly exposed loose end extending from the joint but an inner loose end for opening the joint is formed by extending the portion 40 outside the jaws 10, 13. The handle 60 is returned to the start position to cause the pin 61 to slide upward in the slots 63, 64 and allow the cam 71 to clear a corner 90 of the end 8. In the start position of the handle 60, the cam 70 engages the detent 79 to pivot the arm 75 about its pivot 76 to engage the end 8 and raise the jaw 10. The lever 17 is depressed to raise the surface 20 and the tool is removed from the strapping. In another embodiment, Figs. 11, 12 and 13, a rotatable trigger cam 97 is mounted within a bifurcated end 96 of an operating handle 95 pivotally mounted on the base of the strapping tool by a pin 98. The cam 97 comprises cam surfaces 99, 100 and abutment surfaces 101, 102. Pawls 113, 114 outwardly biased by a spring 115 are positioned in an opening 107 in the cam 97 and extend into openings 109, 110 in the end 96. Similarly, outwardly-biased pawls 116, 117 are mounted in an opening 108. In operation, in the starting position of the handle 95, the pawls 113, 114 extend into the openings 109, 110 and the pawls 116, 117 are pushed within the opening 108 by opposed legs 112, 111, respectively, of the end 96. As the handle 95 is pivoted clockwise of Fig. 12, the cam 97 rotates therewith and the surface 100 approaches, deflects and subsequently releases a vibratory end (121), Fig. 15 (not shown), carrying the upper jaw. In the sealing position, the cam 97 has been rotated through 180 degrees. During the return stroke of the handle 95, the surface 102 abuts the end (121) and prevents counterclockwise movement of the cam 97 and causes the pawls 113, 114 to disengage from the openings 109, 110. Upon completion of the return stroke, the openings 109, 110 register with the pawls 117, 116 which engage therein. During each successive sealing cycle, the cam 97 is rotated through 180 degrees and the surfaces 99, 100 alternate in deflecting and releasing the vibratory end (121).