GB191415565A - Improvements in Mandrels for Metal Tube Forming Machines. - Google Patents

Abstract

15,565. Mackenzie, J. W., [Automatic Welding Co.]. July 9, 1913. Angular bending; bending-formers; drawing; drawing-mandrels. -A mandrel for forming butt-seamed metal tubes from strip stock comprises a cylindrical head in which are mounted a pair of rollers, one roller projecting further from the head than the other, so that the edges of the tube may be permanently set together and prevented from overlapping. The mandrel may be used in connexion with a machine as described in Specification 15,858/13, in which a strip C is drawn by a draft machanism through an adjustable guide G, one or more sets of initial forming-rolls a<1>, a<2> or dies, and a set of forming - rolls b<1>, b<2>, b<3>. The draft mechanism may be dispensed with, and either or both sets of rolls being driven, preferably only the rolls a<1>, a<2>; or driven rolls a<1>, a<2> may be used in conjunction with the draft mechanism. After passing through the rolls b<1>, b<2>, b<3>, the substantially finished tube passes through a pair of rolls b<9>, between which the mandrel d<1>, Figs. 2 and 10, is mounted, preferably slightly forward of the centre of the rolls. The mandrel head is formed in two semicylindrical portions d<16>, d<17> secured together by screws d<18> and containing recesses to receive a pair of antifriction rolls d<14>, d<15>, the lower roll d<15> of which projects further from the head than the upper roll d<14>. The curvature of the groove in the lower of the rolls b' is formed more acute than that of the upper roll, so as to form a small space b<15> between the tube and the lower roll b<9>, into which the portion t<3> of the tube is forced by the mandrel roll d<15> so as to distort the tube and so press the edges together. The recesses in the mandrel head may have flat defining- walls d<28> so as to provide only a line contact with the rolls. The mandrel head portions are provided with complementary recesses in which is fixed a flat rectangular portion of the shank d<2> of the mandrel, which is secured by a member d<3> to an adjustable block d' on the frame B<1>. The mandrel rolls are lubricated through a groove in the mandrel shank in alinement with an inclined groove in the head.