Patent GB-1425206-A (GB)
Title: Strapping tools apparatus for measuring the dust emission of
IPC: B29C65/00
Filed: 1973-07-24
Abstract: 1425206 Seaming non-metallic sheet material FMC CORP 24 July 1973 [24 July 1972] 35182/73 Heading B5K A hand tool for joining overlapping ends of thermoplastic strapping S, e.g. of polypropylene, tensioned about an article P, comprises a strap-tensioning assembly comprising a tensioning wheel 18 and an anvil 20, a pair of relativelyoscillatable, normally-open welding jaws 24, 26, drive means connected to an air motor 14 for rotating the wheel 18 and for oscillating the jaw 26, a clutch 36 for disconnecting the motor drive from the wheel 18 whilst leaving the drive connected to the jaw 26, a release lever 22 connected for releasing the tensioning assembly from the strap S, a weld lever 28 connected for first closing the jaws 24, 26 and thereupon declutching the motor 14 from the wheel 18 so that the motor oscillates the jaw 26 to perform the weld, and a release cam 30 connected to the lever 28 for releasing the tensioning assembly after the jaws 24, 26 have been closed on the strap to eliminate crease failure of the strap S between the jaws 24, 26 and the strap-tensioning assembly during the oscillating welding operation of the jaws. As shown in Fig. 3, the drive means for a shaft 50 carrying the wheel 18 from the shaft 32 of the motor 14 includes a clutch 36 and a brake 38. The clutch 36 includes a toothed driving member 40 and a driven member 42 slidably splined to a shaft 44 formed with a pinion 47A meshing with a gear 48 on the shaft 50. A coil spring 60 urges the clutch 36 towards its engaged position. The brake 38 includes a brake disc 62 having peripheral teeth 63 splined in grooves 64 to prevent rotation of the disc 62. Rearwardly facing jaws (66), Fig. 7 (not shown), are engageable in notches (68) in the member 42 to hold this member against rotation. The release lever 22, Fig. 1, for the anvil 20 is pivoted about a shaft 58 from which depends a member 56 supporting the shaft 50. The anvil 20 has a curved jaw 21 and is mounted on an arm 84 projecting from a hub 82 on the shaft 58. A spring 86 urges the anvil 20 towards the wheel 18. The lever 28 is secured to a shaft 92 having a cam-like nose 94 to engage a rear-face of the member 42 to cam it forwardly towards clutch disengagement position. The shaft 92 has an eccentric portion 96 to force the jaw 26 against the jaw 24 through a plug 98, Fig. 2, three Belleville washers 100 seated in a cup 102 receiving rollers 106 in the upper edge of the jaw 26 which is normally held retracted by springs 116. The jaw 26 is oscillated by a rotary shaft 128, Fig. 3, driven from the motor 14 and having an eccentric portion 134, Figs. 1 and 2, riding in a slot 136 in the jaw 26. A knife 140, Fig. 1, is provided on the jaw 26. The release cam 30 is secured adjustably to the lever 28 by screws 150 and has a body 140A, Fig. 6, notched at 142 to receive a shank 144 of the lever 28. The body 140A is bevelled at 152 to engage the lever 22. In operation, the overlapping strap portions are threaded into the tool and the lever 22 is released so that they are gripped between the wheel 18 and the anvil 20. The operator manually operates a valve 16 to start the motor 14 to drive the wheel 18 until the strap has been fully tensioned about the article P and the motor 14 stalls. The lever 28 is pulled rearwardly from its forward position of Fig. 1. The eccentric 96 forces the jaw 26 downwardly and the nose 94 shifts the member 42 to which the teeth on the members 40, 42 are almost, but not quite, disengaged, Figs. 9 and 10 (both not shown). The jaw 26 is brought into firm engagement with the strap, the knife 140 starts to sever the upper strap portion U without cutting the lower portion and the member 42 is engaged by the disc 62 to brake the wheel 18 so that the motor 14 is operated to oscillate the jaw 26, Figs. 11 and 12 (both not shown). The cam 30 engages the lever 22 to move the anvil 20 away from the strap whilst welding is effected. Figs. 13 and 14 (both not shown). When the weld is completed, the motor 14 is stopped, the lever 28 is pushed forward to open the jaws. The lever 22 is returned to its Fig. 1 position and is then depressed manually to open the tension assembly and allow the tool to be removed.