| 摘要 |
961,798. Making bags with tear strips. TRANSPARENT PACKAGING Ltd. Nov. 28, 1962 [Dec. 5, 1961], No. 45071/62. Heading B5D. [Also in Divisions B8, F2 and H5] A plastics tear strip is heat sealed to a seamless plastics tube by co-operation of a sealing head 50 (Fig. 2) and a floating anvil 6 within the tube. In the form shown, the tear strip is fed across the tubing by a shuttle arm 10 and is then clamped in position by a gripper 42 and severed by a cutter 64. Rollers 7, which may be mounted on ball-bearings, on the anvil 6 cooperate with rollers 5 outside the plastics tube to hold the anvil in position. A sealing pad 9 of silicone rubber is provided on the anvil 6 which may be made of aluminium. The head 50 is lowered under the control of a relay which is slugged to hold the head in welding position for sufficient sealing time. The shuttle arm 10 is moved by a rack 11 driven by a gear 12 and is returned by a spring. The size of the anvil 6 and head 50, and position of the clamping device 42 may be altered to suit different sizes of bag. The apparatus may be associated with known plastics bag forming machines such as in Fig. 9 in which the tubing is fed from a roll 73, has the tear strip 31 attached as previously described and the tubing is subsequently sealed at intervals by the head 75 and cut into bags by the guillotine 76. |
