Improvements in Bending Machines for Making Metal Tubes

28,073. Pfrengle, O. Dec. 3,1908, [Convention date]. Angular bending.-In making long tubes of small diameter from plates of considerable strength, the plate is bent by jaws on a mandrel passing through a number of short machines placed side by side to form a single machine driven from one common shaft, so as to prevent twisting of the mandrel and the springing of the jaws. A series of standards a have guides 1 to receive segments b, which are rotated by racks and pinions i from a shaft k geared to a shaft m, which is rotated by crossed or open belts through a friction clutch. The segments have vertical guides 2 for the cheeks c, c , which carry the bending-jaws d, d , and are adjusted towards the hollow mandrel e by right and left handed screws f rotated by a handwheel g through bevel-gear. The mandrel is supported by pins r on pivoted arms q; removable half-rings s are inserted in the frames to prevent springing of the metal. The plate u, Fig. 1, is fed in over rollers p on adjustable brackets o, and is clamped between the jaws d and the mandrel. On rotating the segments until the metal is wound more than a quarter of the circumference of the mandrel, the jaws are released and the segments returned, leaving the metal on the mandrel. Further portions are then wound on the mandrel by similar operations until the tube is completed.