Improvements in and relating to tubes formed by helical winding

743,115. Cutting tubes. ROBINSON, E. B. May 9, 1952 [Feb. 9, 1951], No. 3156/51. Class 31 (1). [Also in Groups XXVIII and XL (b)] In apparatus for producing rims, i.e. lengths of tubing appropriate to form the bodies of containers by winding strip material helically on a mandrel to form a tube, and cutting the tube into lengths under the control of marks or irregularities on the strip or the tube, the control means is caused to be alternately in operative and inoperative states for such periods that the control means is operated by every mark, alternate marks only or by every third mark, and so on. The control means may be rendered operative immediately before a control mark arrives at a detecting position and inoperative immediately the cut is completed, and may remain inoperative until immediately before the next control action. Forming the tube.-A web 5, Fig. 1, bearing patterns printed at an angle with trim spacing between certain patterns is drawn off a roll 6 and over a gumming roller 2 to a detector unit 8 (see Group XL (b)) comprising a photoelectric-cell detector 12 adjustable on guides 13, 17 at right angles. The detector is influenced by marks &c. on the strip as in Specification 653,613 and controls the cutting mechanism. Cutting the tube into rims. A circular saw 24, Fig. 5, is moved up to the tube, travels along with it for the cutting operation, and is then withdrawn and returned to starting position. The saw 24 is carried by a motor 22 mounted, with provision for setting relatively to the work, on a bracket 28 carried by an arm 21 rocked about a shaft 31 by cams 42, 43, Fig. 9, engaging rollers 40, 41 on a shaft 37 carrying a frame 36 engaging a roller 34 on the end of the arm 21 which is in two parts connected in adjusted position by a bolt 44. The longitudinal movement of the saw, during which the roller 34 rides in a slot 35 in the frame 36, is effected by a cam 52 rigid with the cams 42, 43 and mounted on and rotated by a shaft 153 driven by variable-speed friction wheels 59, 58 and gears 55. The cam 52 reciprocates a slide, to which the shaft 31 is fixed, and the shaft at the end of its forward stroke engages a plunger to reset the electrical control mechanism. The shaft 153 is clutched to the cam 52 by a ratchet 64 and pawl 65, Fig. 11, whenever a spring- pressed catch 67 is withdrawn by a solenoid 75 acting through links &c. 73, 71, 70, the solenoid being energized under the control of the detector. The shock of starting the cam may be absorbed by a spring 76 situated between members 77, 78 associated with the ratchet. The cam is stopped at the end of a revolution by a pawl which drops into a notch in a ring mounted on the cam with provision for a limited rotation, an inner ring being fixed to the cam, and a spring being interposed between the rings. The pawl is released by means operated by the catch 67 when the cam is ready for another revolution. Specifications 743,123 and 743,170, [both in Group XXVIII], also are referred to.