GB246967A - Improvements relating to the manufacture of pipes and the like from metal sheets orplates - Google Patents

Abstract

246,967. Hume, W. R. Dec. 15, 1924. Pipes; poste.-Metal pipes and tubes, tubular tramway or telegraph posts, &c. are made from sheet metal by first winding a sheet of width equal to the length of the tube into a continuous spiral long enough to form one or more tubular articles, and then severing the spiral and joining the meeting edges of the blank or blanks longitudinally at one or more positions. The winding mandrel 12 is of spiral form to prevent the formation of ridges &c., having a step 3 of height equal to the thickness of the sheet and a rounded edge 12. A slot may be provided to receive the end of the sheet or the sheet may be tacked to the mandrel so that its end abuts against the step. Winding is effected by rotating the mandrel in contact with a pressure roller 13, Fig. 6. A two-part mandrel, Fig. 6, may be used, the sections 16 being clamped on a shaft 17 by bolts 15 so that, after winding, the shaft may be removed and the sections contracted to remove the completed spiral. The spiral may be transported or shipped in this form or the convolutions may be first longitudinally severed and then transported in this form. space being thus economised. In forming a single tube, Fig. 3, the overlapping edges are severed by a cutter such as a saw, milling cutter, or oxyacetylene or electric arc cutter, preferably a bevelled cutter 21, the cut being effected either adjacent the outer edge or through both layers. In making a series of tubes of different diameters, the spiral may also be severed at one position only by bevelled cutters &c. In making a series of tubes of the same or of required diameters the flat sheet may be previously grooved or marked at the desired positions 27, Fig. 8, by a bevelled rotary tool and' then wound so that the marks are on the outer side of the spiral, the convolutions being severed individually along the marks. In order to avoid damage to the underlying convolutions, particularly when cutting by flame or electric arc, the outer convolution is spaced from the rest of the spiral by wedges 26, Fig. 10. The blanks are subsequently removed from the mandrel or from a shaft on which the spiral may subsequently have been placed before severing and the bevelled edges thereof are welded by additional metal on a segmental former or in a cylindrical or other mandrel of required size. A series of tubes of different diameters obtained by taking a single cut in the spiral may be united at their ends by riveting or welding to form a tapered tube or pole. In effecting the winding and severing operations, the mandrel may be secured to a face plate 36, Fig. 14, rotated by gearing 46, 44 from a shaft 41. The outer reduced end 50 of the mandrel is normally held by a screw-adjusted bearing block in a bearing 37, which is trunnioned at 48 so that it may be swung down to remove the completed spiral. The bearing is normally held in raised position by toggle links 53. The pressure roller 13 is held by projections 56 in a frame 54 which has inclined lower faces 72 resting on screw jacks 73 and which at its ends has apertured lugs 57 engaging the eccentric ends 58 of a shaft 59. This shaft is driven by spur gear 64, 63 and chain or band gear 62 from the mandrel shaft so as to cause the pressure roller to recede as winding proceeds. The presure roller is restored to its normal position by worm gear 66, 67 operated by a hand wheel 69. The screw-jacks may be adjusted by worm gear to give a fine adjustment. In order to prevent distortion of the mandrel at the beginning of the winding operation, the mandrel abuts against the curved end 77 of an arm 76 which is pivoted at 81 to a screw-adjusted block 82. Rotation of the mandrel raises the arm until it comes out of contact therewith, whereupon the arm is raised still further by a weight 75. The cutting is effected by a bevelled tool 21, laterally adjusted by a screw on a slide 89 which is traversed by a rack 92 and pinion 93 rotated by a driving shaft 94.