GB990321A - Improved machine for helically corrugating metallic tubes - Google Patents

Abstract

990,321. Corrugating. TREFIMETAUX. Dec. 10, 1963 [Dec. 13, 1962], No. 48779/63. Heading B3E. A machine for corrugating metallic tubes, e.g. aluminium sheaths of electric cables, comprises a rotary tool holder through which the tube to be corrugated is passed axially and is characterized in that the holder is fitted with at least one corrugating member consisting of a rod extending radially through the holder into the bore thereof which carries at its inner extremity a projecting rotary ball and a device for regulating the depth of the ball within the holder. The machine comprises a frame 1 in which is rotatably mounted a sleeve 2, driven via a pinion 4, to one end of which is keyed and screwed a tool-holder 5 having a hard plastic flanged bush 9. Four screwed rods 15, in the end of which are located and retained superposed balls 17, 18, are located in tapped radial holes 13a-13d and extend through aligned holes in the bush 9 which is an interference fit in the holder 5. The holes 13a-13c are angularly spaced within an angle of 90 degrees whilst the fourth hole 13d is further angularly displaced from the preceding hole, all of the holes being positioned along a helical path. A second set of similarly arranged holes 14a-14d are provided for producing corrugations of a different helical pitch. Vernier type adjustment of each of the rods is effected via a graduated scale marked on a flattened portion thereof in conjunction with a graduated chamfer about the tapped holes 13. The leading ball 17 is of a larger diameter than the succeeding ones which may also vary in diameter. With the tool-holder 5 rotating, the rods 15 being so adjusted that the forming balls 17 produce a progressive increase in the depth of corrugating, a tube 30 is initially axially moved into contact with the balls which corrugate the outer wall thereof. The tube is subsequently drawn through the tool by the action of the tool thereon, the tube being backed up by the portion of the bushing opposite to the balls. In an example the tool-holder speed is 800 r.p.m., the corrugation depth and pitch 3.2 mm. and 14 mm. respectively, the initial and final tube diameter 38.3 mm. and 37.2 mm. respectively, a nd the tube feed rate 1.12 metres per minute.