Patent GB-551738-A (GB)
Title: Improvements relating to the closure of collapsible containers
IPC: B21D51/36
Filed: 1941-11-04
Abstract: 551,738. Making collapsable tubes. BOOTS PURE DRUG CO., Ltd., and RANDALL, W. J. Nov. 4, 1941, No. 14220. [Classes 83 (ii) and 83 (iv)] Uniting by fusion.-In electric-arc welding the edges of the flattened end of a collapsable tin, lead or tinned lead &c. tube for containing a pasty or liquid material, a pivoted electrode subjected to resilient pressure is presented to the leading corner of the end of a tube held in vicelike jaws so that the tip of the electrode gently urges over the corner and thus initiates the arc. The filled tubes are placed in carriers 2 on a chain conveyer traversed step by step past a number of operating stations A - E. At A the open end of the tube is flattened between a pair of jaws 21, 22, Fig. 5, mounted on slotted levers 14, 15 pivoted at 16 and operated by an arm 19 on a shaft 7 rocked through levers 13, 9, Fig. 10, and connecting rod 12 by a cam on the shaft 5. This shaft may be turned by hand for setting purposes. At the station B the flattened end is clamped between jaws 23, 24, Fig. 7, pivoted at 25, the jaw 24 being slotted at 26 to engage the pin 27 on an arm 28 mounted on the shaft 7 so as to close the jaw 24 and the short arm 29 comprising a spring 30 so as to press on the teeth of the jaw 23 to grip the end of the tube as shown in Fig. 7. The pin 27 continues to move down the slot 26 after the jaws are closed and pushes down the member 131 carrying the shear blade 32 which is pressed against the sloping surface of the jaw 23 and shears off a portion of the end of the tube. At station C the end is again pressed flat by jaws operated similar to those shown in Fig. 5. At station D the blank is first pushed against an insulated end stop 41, Fig. 11, on an electrode slide 38 by a head 51 separated by a spring 52 from a cam operated plunger 50. The tube is then gripped between copper jaws 36, 37, the jaw 37 being closed by a spring 54 connected to a lever 57 operated by a cam 55 on the shaft 5. The jaws 36, 37 are connected to the positive pole of a source of direct current. The electrode slide 38 is traversed on rods 39 against the action of a spring 40 by a cam-operated lever 59. In the slide is mounted a slide 45 transversely adjusted by a screw. The slide 45 carries a copper electrode 43 pivoted at 63 and connected to the negative pole of the circuit. The electrode has an insulated stop 43a which is normally pressed by a spring 49 or gravity against the wall of a slot in the slide 38 so that the electrode is vertical. During traverse of the slide 38 the tip of the electrode meets the leading corner of the tube projecting from the jaws 36, 37 and the electrode is tilted slightly and moves over the end of the tube. Just before the tip touches the comer of the tube the arc is initiated by a high voltage high frequency current injected into the welding circuit the current being generated by means of a spark coil and interrupter or by a back coupled thermionic valve circuit. The arc melts down the projecting part of the tube in advance of the electrode which returns into vertical position to complete the weld immediately after the initial tilting. During welding the parts are shielded by nitrogen or other inert gas supplied preferably through a pair of tubes 66. Instead of adjusting the slide 45 laterally by hand to vary the operative portion of the electrode, it may be automatically adjusted by gearing from a slow moving part of the machine or by a synchronous electric-clock. At the station E the end of the tube is finally squeezed by pivoted jaws 69, 70, Fig. 14, operated from the shaft 7 through toggle links 68. The electrode 43 is mounted on an eccentric on the spindle 63 which is adjustable by a hand lever 65 to vary the height of the electrode above the work. Specification 500,491, [Group XVII], is referred to.