Patent GB-444695-A (GB)
Title: Improvements in and relating to apparatus for stretching straps about boxes, packages, bundles, or the like, and sealing the overlapping strap ends
IPC: B65B13/34
Filed: 1934-09-25
Abstract: 444,695. Seals and sealing. BURGESS, A. F., 10, New Court, Lincoln's Inn, London.- (Acme Steel Co. ; 2840, South Archer Avenue, Chicago, U.S.A.) Sept. 25, 1934, No. 27509. [Class 146 (ii)] [See also Group I] In a device for strapping boxes, the strap sealing jaws are arranged in a movable sealing head so as to receive a seal from a magazine when the head is in retracted position and to carry the seal into position embracing the overlapping strap ends when the head is moved into the operative position. The machine comprises a base-plate 33 on which are mounted stationary and movable grippers 35, 34, the sealing head A with cutting mechanism, and the magazine 115 and feed device 120. The end portion 27<a> of the strap is held in position as shown in Fig. 2 by a pivoted dog 35 which prevents movement of the strap to the left. The supply portion of the strap after passing round the package is held against movement to the right by a pivoted dog 47 and is passed under the sealing head 80, over a fixed cutting die 110, and through a guide groove 38 in the dog 35. The dogs 35, 47 are mounted in blocks 34, 44 seen in plan in Fig. 5. The block 44 is carried on a slide bar 46 which is moved to the left to tighten the strap by the hand lever 70 with crank arm 69, the link 65, and the lever 60 which is pivoted at 62 on the radius link 63. By this arrangement, the hand lever moves the slide bar 46 with decreasing speed and increasing force. A spring 77 and friction washer 76 keep the lever 70 stationary whilst the strap is being placed in position. The strap is cut, and the overlapping portions secured by a seal, by the operation of a hand lever 92. The sealing device comprises gripping levers 83, Figs. 12, 16, 17, pivoted at 84 in side-plates 81 which are themselves pivoted on the base at 82. A seal 30, Fig. 4, carried by the open jaws is brought into position over the strap by lowering the plates 81 about their pivot and the jaws are then closed to form the joint shown in Fig. 3. In this operation the seal bears against a block 85 in the side plates 81. Parts of the width of the jaws are shaped as shown in Fig. 16 to bend the sides of the seal beneath the strap, and between these parts are cutting dies 87, 87<a>, Fig. 17, which shear the edges of the seal and strap, and deform parts of the metal as shown at 32, Fig. 3, forming interlocking shoulders along the length of the joint. The hand lever 92 is pivoted at 93 in the side plates 81, and operates the levers 83 through links 90, Figs. 10 and 12. One lever 83 is connected with the pivot 82 of the side-plates by toggle-links 96, 97 which are self-locking when the jaws are fully open so that initial movement of the lever 92 lowers the side plates 81 until the toggle-joint is broken by the engagement of the pin 101 with the baseplate. The other lever 83 is connected with the corresponding link 90 with lost motion and carries a spring-pressed pin 103 which in the open position engages the first lever 83 so that the jaws form a spring grip for the seal resting on the projection 83<c>, 83d. For severing the supply portion of the strap, a cutting blade 112 on a shearing lever 113, Fig. 10, co-operates with the fixed cutting blade 110<a>. The lever 113 is pivoted on the baseplate at 111 and is operated by a link 114 which is pivoted at 114<a> on the plates 81. A spring 119 connected to the baseplate normally holds the cutting blade 112 and the side plates 81 raised above the strap and in contact with a stop-flange 109<a>, Fig. 12. The movement of the plates 81 by the operating lever causes the blade 112 to sever the strap before the seal is applied. A spring 124 ensures the return of the operating lever 92 to the initial position with the jaws fully opened. The seals 30 are fed automatically from a magazine 115, Figs. 2 and 13. The seals are indented as shown at 30e, Fig. 4, so as to make only point contact with one another in the magazine, and the bottom seal resting on the guide plate 117 is fed forward into the open jaws by the plunger 120'which is operated from the slide bar 46. A spring-pressed pin carried by the slide bar engages an inclined surface on a lever connected with the plunger 120, and when the seal has reached the limit of its movement and bears against the stop 81<b>, Fig. 13, the pin can pass the lever during the further movement of the slide bar 46 for tightening the strap. The stop-flange 109<a>, Fig. 12, is carried by a lever 109 pivoted at 73 and adjustable by screws 109<c>, 109<d> to bring the jaws 83 into alignment with the magazine. The seals are pressed downwards in the magazine by a weight 140 carrying a pivoted spring-pressed latch which prevents upward movement until released by raising the handle 144.