Patent GB-350486-A (GB)
Title: Tube manufacture
IPC: B21D15/02
Filed: 1929-12-09
Abstract: 350,486. Making tubes, posts, &c. DEHN, F. B., 103, Kingsway, London. - (Union Metal Manufacturing Co. ; 1432, Maple Avenue, North East, Canton, Ohio, U.S.A.) Dec. 9, 1929, No. 37759. [Classes 83 (ii) and 83 (iv).] Angular bending; dies; formers; rolling .flanged a n d profile bars; cold rolling.- In the manufacture of tapered fluted tubes such as pillars, posts and standards for telephone, telegraph, transmission and trolley suspensions, &c., a metal sheet blank is thickened at the edges to facilitate welding the seam, is bent to circular section between semicircular dies and a mandrel and is then drawn between dies to set the bend and is fusion-welded at the seam on emergence from the dies. A tapered sheet blank R, Fig. 4, is first passed through a cold-rolling mill comprising rubber feed rollers 9 and coacting rolls 1, 2 for forming the thickened edges 3, 4, the rolls 1, 2 at one side being rigidly mounted and the others pressed towards them by a fluid pressure ram to allow for the taper of the plate. Further narrow metal feed rolls may be supplied. The rolls may produce the interlocking sections shown in Fig. 4 or any of the sections shown in Figs. 23-27. The sheet is next placed on a table adjacent a bending machine B, Fig. 6, and is located thereon by stops whilst each end is secured in a clamp secured to an endless chain 11. The chain is then advanced by means of sprocket wheels and a reversible electric motor to place the sheet under a mandrel 36, suspended by adjustable rods 37 and nuts 43 from the upper structure 33 of the machine. The lower surface of the tapered mandrel is horizontal and contains a groove 83 for accommodating the chain 11 and clamps. When the sheet has been advanced to the correct position a dog on the chain 11 operates a switch to stop the motor, the sheet remaining stationary and gripped to the chain. A motor 24 is then started, which drives, through gearing 21, 17, two eccentric-shafts 16, 16<1> and through gearing 27 a central cam shaft 28. The latter operates on links 46 guided vertically by brackets 44 and attached to a central die-plate 50 to raise the sheet to within a short distance of the mandrel but not in contact therewith. Jaw dies 51, 51<1> are pivoted at 55, 551 respectively on the die-plate 50, the pivots being at the opposite sides of the plate from the dies as shown in order to increase the leverage of the dies. Connecting rods 59, adjustable in length by right- and left-hand screws and lock-nuts 62, 63 are pivoted at 58 to the dies and are operated by the eccentrics 60 to raise the dies, together with the die-plate 50, and then to close them round the mandrel, the jaws acting on the sheet through rollers 66 in order that the bending forces may always act on the sheet at right-angles thereto. The dies 51 conform to the conical shape of the mandrel and are built up of any number of sections according to the length of sheet being bent, one eccentric 60 being provided for each section. Drawing ; drawing-dies ; uniting by fusion.- The curved sheet with an open seam is next passed to a draw-bench C, Fig. 7, in alignment with the bending machine B. The sheet enters a bell 97 to which are pivoted at 102 four dies 99, 100, the lower die 100 being stationarily supported by a bracket 109 whilst the upper die 99 is pressed downwards by a fluid pressure cylinder 106 pivoted thereto at 108. The dies are guided in a crossshaped opening 104 in a fixed face-plate 103. The tapered tube is drawn through the dies by means of a draw-bar clamped thereto, a longitudinal slot 110 in the lower die accommodating the bar and clamp. On emerging from the dies the thickened metal at the edges of the seam is fused without the addition of further metal in any of the shapes shown in Figs. 23-27, by means of an electric arc or torch 118 and an anvil 119. The shapes shown in Figs. 4, 24, 25 and 26 may produce a joint flush on the outside of the tube and thickened on the inside or thickened on both sides, whilst those shown in Figs. 23 and 27 may form a joint thickened on the outside and flush inside or flush on both sides. The joint shown in Fig. 25 has a recess 3c<1> for retaining flux and the flat surfaces 3b<1>, Fig. 24, may be knurled for this purpose. The cold rolling of the sheets to produce the thickened edges is stated to remove scale from the edges to be welded. Corrugating ; corrugating-dies ; cold rolling ; rolling tubes ; die rolling ; rolling mandrels ; separating mandrels from work; physical or molecular structure, altering by mechanical treatment.-To increase the strength of columns &c. by longitudinal fluting, a machine similar to that described in Specification 269,078, [Class 83 (iv), Metals, Working], is used. The tube is placed on a mandrel 148, Fig. 8, having radially projecting ribs 149 formed with V-shaped outer edges, and is passed one or more times between sets of radially yielding rolls 150, 1501 which partly form the flutes by bending and produce sharp cornered fillets 151. The rolls are arranged in more than one set, as shown, in order to be accommodated in the circumference. This rolling operation, which is performed cold, is stated to swage the fillets to increase the thickness of metal therein and also to increase the elastic limit of the metal in the flutes and fillets by changing the molecular arrangement thereof. The length of the tube is also increased. The tube, still on the mandrel 148, is next passed through sets of yielding rolls 153, 153<1>, Fig. 9, which complete the forming of the flutes and set the metal therein to relieve it of flexing strains so that the tube will retain its shape even when severed longitudinally into halves. To release the tube from the mandrel it is again given one or more passes through the rolls 150, or alternatively the flutes may be formed first by the rolls 153 and the tube then passed through the rolls 150 to form the fillets and loosen the mandrel. In a modification the mandrel conforms exactly to the interior shape of the tube and the flutes and thickened fillets are formed simultaneously by rolls such as 153. Instead of forming fillets of the Doric order, as shown in Fig. 8, sharpedged fillets 152, Fig. 33, of the Ionic or Corinthian order may be formed by rolls 150a<1> used in the same manner as the rolls 150. Dies other than roller dies may be used for the fluting operations.