Patent GB-1136846-A (GB)
Title: Improvements relating to strap sealing
IPC: B65D63/14
Filed: 1966-07-15
Abstract: 1,136,846. Seaming non-metallic sheet material. SIGNODE CORP. 15 July, 1966 [16 July, 1965; 13 Aug., 1965; 2 Feb., 1966 (2)], No. 31847/66. Heading B5K. [Also in Division F2] A length of thermoplastic strap S is formed into a loop encircling an article A so that the loop is provided with overlapping strap portions U, L, the loop is maintained about the article A while effecting sliding frictional between contacting surface regions of the portions U, L until interface melting occurs and the portions U, L are pressed together until the melted surface regions solidify. The strap may be tensioned and sealed by separate means utilized in side-by-side relation or these two means may be integrated. The strap may be made of nylon or polypropylene. The joint need not be continuous across the entire width of the strap but may have a channelled pattern consisting of laterally spaced lengthwise strips in the joint area. To effect interface melting, one strap portion may be reciprocated with respect to the other strap portion, e.g. by the embodiments described with reference to Figs. 3-11 (not shown), identical with those shown in Figs. 3-11 of Specification 1,136,845. Alternatively, the interface melting may be effected by giving one strap portion a singlestroke movement in a lengthwise direction with respect to the other strap portion. In one embodiment, Fig. 12, the strap S is loosely formed about the article A and a tool 80 is applied sidewise over the portions U, L so that a foot 81F contacts the article A. A lever 87 is actuated to load a feed wheel W mounted on a shaft 86 towards an anvil 88 to grip the portions U, L. An air motor 89 is actuated to drive the wheel W to tension the loop to a predetermined value determined by a stall setting for the motor. The free end, i.e. the end leading to a strap supply, of the portion U is firmly engaged by a clamping mechanism 93 mounted on a piston 94 operating in a cylinder 90. A control button 95 is actuated to apply air pressure to the cylinder 90 to move a jaw 91 to press the portions U, L against a jaw 92. The wheel W is lifted by the lever 87 so as not to restrict the portions U, L adjacent the wheel W from movement. A control button 96 is actuated to thrust the piston 94 and thus the mechanism 93 from the full to the dotted line position of Fig. 12. The rapid movement of the mechanism 93 causes the portion U, after slight elongation, to longitudinally slide on the portion L whilst the portions are pressed between the jaws 91, 92 to effect sealing. The jaws 91, 92 are released after solidification. In another embodiment, Fig. 13A, a manual tool comprises a foot 101F to contact the article A. Initially, two sets of jaws 104, 105 and 107, 108 are open and a feed wheel W is elevated above an anvil 102. A handle 103 is actuated to lower the wheel W and is then repeatedly swung to ratchet the wheel W and draw tension on the loop. A lever 106 is actuated to engage the jaws 104, 105 to hold the portions U, L and the wheel W is elevated and a slack region (R), Fig. 13B (not shown), is manually drawn up between the jaws 104, 105 and 107, 108. The sealer jaws 107, 108 are then closed by a lever (not shown) similar to the lever 106 and the wheel W is relowered. The handle 103 is actuated to draw tension on the strap between the wheel W and the jaws 107, 108 and the slack (R) is rapidly drawn through the jaws 107, 108 to effect friction sealing. In a modification, Fig. 13E, a power tool comprises tensioners 110, 111 flanking sealer jaws 107, 108. In use, after threading the strap through the device, with the jaws 107, 108 open, the feed wheels W of both tensioners are rotated with the wheel W of the tensioner 111 having a speed slightly greater than that of the tensioner 110 to build up a predetermined slack R between the wheels W. The jaws 107, 108 are then closed and the tensioner 111 only is operated so that the portion U slides on the portion L through the jaws 107, 108 to effect friction sealing. In a further embodiment, Fig. 14, the device comprises foot portions 121, 122 which contact the article A and feed rolls 123 which draw strap from a supply (not shown) and feed it around the article using a shoot (not shown). The rolls 123 are then reversed in direction to tension the strap loop. A mechanism 124 to hold the strap loop under tension comprises a wheel 128 which is held elevated whilst the loop is threaded through the device. Air is then admitted to the right of a piston 125P to drive a link 127, on which the wheel 128 is mounted, to move the wheel 128 towards the anvil 121 whilst the rolls 123 tension the loop by pulling the portion U. A pawl 124 prevents reverse movement of the wheel 128. During the threading and tensioning of the strap S, a cam 137 is held in the position of Fig. 14 by a spring 140 acting between a fixed seat 141 and an extension 137A. A cutter blade 142 rides on an upper jaw 131 having a central post 132 slotted to receive one end of a link 133 pivoted on the frame of the device. Rod ends 132E on the post 132 ride in a slot 137S in the cam 137. The blade 142 is actuated by a shoulder 143 on the cam 137. A piston 134P is elevated in a cylinder 134 and frees the link 133 and rotates the cam 137 clockwise through a rod 136 having a hooked end 136H which engages the extension 137A, Fig. 16 (not shown). Springs 139 cause the jaw 131 to press the portions U, L against the foot 122. Towards the end of upward travel of the piston 134P a shoulder 136S on the rod 136 engages a shoulder 141 on the stop 141 so that the rod 136 swings clockwise to release the cam 137 and allow the spring 140 to rotate the cam 137 rapidly, Fig. 17 (not shown), to cause the jaw 131 to move rapidly forward under pressure to effect friction welding of the portions U, L. After a cooling interval, the rod 136 is lowered to engage the link 133 and lift the jaw 131.