Patent GB-902678-A (GB)
Title: Tube forming method and apparatus
IPC: B21C37/12
Filed: 1959-07-30
Abstract: 902,678. Coiling helically jointed tubing; welding by pressure. RAYMOND INTERNATIONAL Inc. July 30, 1959 [Jan, 2, 1959], No. 26224/59. Classes 83 (2) and 83 (4). [Also in Group XXVIII] A method of forming flexible strip material into helically wound tubing comprises con. tinuously-feeding the material longitudinally to straight rows of outer forming rolls of small axial dimension disposed to define a substantially cylindrical envelope, such material being fed obliquely with respect to the axis of the envelope in such a direction as to be curled by the forming rolls into a tubular helix coaxial with the envelope while maintaining each roll substantially in alignment with the path of travel of the material at the point of contact thereof with the roll, and continuously joining contiguous edges of the material forming the tubular helix. As shown, the strip 20 of metal is fed from a rotatably mounted coil 22 between a series of idling rolls 33 which flatten the strip prior to entry between pairs of feed rolls 26, 27 driven by a motor 30, the rolls being mounted on a frame 24 pivotally mounted at 34b for rotation about the horizontal axis of the tubing 21. The tube former 25 includes an entry guide box 34 consisting of plates 36, 37 mounted on studs 40, 40a and angularly adjusted by the bolts 44, 45. The former 25 comprises end frames 61, 62 which receive flanged members 65, 66 carrying bars 71 bifurcated at the ends thereof in both transverse directions to provide four parallel prongs for reception of trunnion blocks 79, 80 whereby the bars are adjusted radially outward and inward with respect to the axis of the tubing; endwise adjustment of the bars is effected by bolts 84, 85. Journalled in the bars 71 are caster roll assemblies each including a roll 90 eccentrically arranged with respect to a spindle such that the assembly will be automatically aligned with the path of travel of the tubing; the assemblies each carry a lever and are ganged together by bars so as to be concurrently adjusted to the same angular relationship with respect to the surface of the tubing. The rolls form an outer envelope within which the strip emerging from the guidebox 34 is guided, bent and curled into tubular configuration and also axially displaced by virtue of the action of the guide box. Initial upward curling of the strip as it emerges from the guide box is facilitated by a row of rolls 132 which engage the interior of the tubing and are rotatably mounted on spindles 131 carried by a fixed mandrel 127b. The adjacent edges of the convolutions of the strip are heated by a highfrequency heating unit and the fused edges are passed between cooled rolls 181, 182 to effect a butt or lap welded joint between the edges; where the strip is of a plastic the rolls (131) (132) are heated to join the edges by heat-sealing pressure. In a modification, each bar carrying the rolls is secured to a block 204 slidably mounted between a pair of guides 205, 206 disposed radially with respect to the axis of the tubing 21, each block being mounted on a screw-threaded spindle 211 connected by worm gearing 218, 219 to a shaft 220 driven by a reversible motor. Mounted on each shaft 220 is a pinion 223 which meshes with a ring gear 224, or a chain. Rotation of the motor in the appropriate direction causes corresponding rotation of the gear 224 and consequent radial inward or outward adjustment of the rolls. Specification 853,673 is referred to.