| 摘要 |
A machine and method are disclosed for securing a loop of thermoplastic strap around an article so that two overlapping portions of strap are bonded together. One form of an apparatus in the machine has a strap engaging weld pad with spaced-apart, parallel strap-engaging ribs for effectively making a friction-fusion weld in thin film strap. Another form of the apparatus in the machine includes a rack gear associated with a weld pad and engaged with an arc of teeth on a torsion bar for utilizing the torsional oscillation kinetic energy to reciprocate the weld pad along a linear path of motion. Another form of the apparatus in the machine includes a strap carrier chain for forming the strap in a loop about an article and the chain may include a resilient lug positioned between each pair of adjacent cross pins in the chain. Another form of the apparatus in the machine includes (1) means for reciprocating an anvil between a retracted position and an extended position below an article, (2) grippers and cutters connected with a linkage system to move the grippers and cutters between a closed position against the anvil and open position away from the anvil, and (3) carriages for moving the cutters and grippers from a retracted position to an extended position independently of the anvil. All of the forms of the apparatus may be used separately and independently of each other in various other types of strapping machines. |
