GB686867A - Tube-stretching machines - Google Patents

Abstract

686,867. Rolling tubes. SINGER, F. Nov. 13, 1950, No. 27641/50. Class 83 (iv). In a tube rolling machine of the kind in which a tube is fed in step-by-step manner over a mandrel of larger diameter than the original diameter of the tube, the tool for stretching the tube comprises a plurality of rollers or oscillatory segments embracing the tube and mounted on a reciprocating member of the machine. A tube 5, Fig. 1, is fed step-by-step over a fixed mandrel 4 to a stretching die comprising three rollers e on a slide a reciprocated by a connecting rod d. The rollers e have circumferential grooves to form a circular pass for the tube and are mounted on spindles f in a headstock c. The headstock c is intermittently rotated about the tube axis to eliminate ridges, by a pair of rollers n, Fig. 2, mounted on the machine base b and which oscillate a two-armed cam k pivoted on the slide a to alternately compress spring-loaded push-rods m coupled to spring-loaded grippers g encircling the headstock c and giving a frictional drive in one direction only. In a modification, the headstock c does not rotate and the ridges formed by the rollers e are removed by a second set of smoothing rollers which may be attached to the headstock or to a fixed part of the bed b. In a further example, the rollers e are replaced by oscillatory grooved segments e<SP>2</SP>, Fig. 6, mounted on trunnions v on a rotary headstock c. The segments have integral toothed quadrants w engaged by racks x yieldingly supported against longitudinal movement in an annulus 2 which is rotatable in a bracket 3 secured to the machine bed so that the racks are free to rotate with the headstock.