GB308419A - Manufacture of spiral metal pipe - Google Patents

Abstract

308,419. Dehn, F. B., (California Corrugated Culvert Co.). Feb. 7, 1928. Pipes.-Helical metal pipes are made by coiling a sheet of metal into tubular form, the edges being crowded together to form a lapped seam, and then fusing the edges to form a joint of greater thickness than that of the sheet. The edges may be overlapped to form a seam of double thickness, the seam being completed by fusing along the edges of one convolution. The sheet 10, which is guided by rollers 13, is fed by rolls 11 at an angle beneath rolls 19, 20 and over a roll 18 to coil the strip into tube form. The roll 18 is driven from the main shaft and drives the rolls 19, 20 by gearing 27 and universally jointed shafts 28. These rolls are driven at a greater speed than that of the feed rolls, so as to provide a slight slip between them and the surface of the sheet so as to avoid excessive friction between the edge 10<b> of the sheet and the guide rollers and reduce friction caused by the endwise slip of the sheet off the roll 18. The rolls 18-20 are mounted in a base pivoted at 36 so as to adjust the angle of feed according to the diameter of pipe or width of strip. The roll 18 is mounted in bearings in the yoke 15 and also in a bracket 22 positioned so as to clear the upwardly curving edge 10<a> of the sheet. The rolls 19, 20 are mounted in bearings in beams 23, 24 fixed to the yokes 16, 17, the beam 24 being adjustable by screws 25 to suit the diameter of the tube. The seam is fusion welded by a burner 38 or electric arc, the edges being crowded together to tend to cause them to overlap and so provide metal to form a seam 39 of greater thickness than that of the sheet and thus avoiding the use of additional welding material, by offsetting the tube by passing it through a guide 29 angularly adjusted by a screw 37 along a curved track 35 centered at 36. The guide is provided with rollers 31, mounted in swivel brackets 32, one of which is adjustable by a screw 34 to suit the diameter of the tube. The angle of feed may also be varied by swinging the feed mechanism 11 with respect to the bending mechanism. The machine. may also form a tube with an overlapped seam, Fig. 7, welding being then effected at 40. The bending rolls 19, 20 may be replaced by a series of spindles 41, 42, Fig. 8, driven by worm gear 45, 46 from shafts 47, 48 and having button-shaped heads 43, 44, to assist in feeding the sheet forward. In a further modification, the bending rollers are replaced by a series of pairs of rolls 51, Fig. 9, co-operating with a series of idle rolls 63. The pairs of rolls 51 are mounted in swivelling-sleeves 49 which are provided with arms 56 connected together by a rod 57. The rolls are driven by bevel gear 52 from shafts connected by gears 54, and operated by bevel gear 55 from the main drive. The beam 24<1> is pivoted at 58 and is adjustable by lever and link mechanism 59 operated by a screw 61. The rolls 63 are carried in brackets 64 swivelling at 65 and connected together by a bar 67.