Patent GB-193437-A (GB)
Title: Improvements in tube bending machines
IPC: B21D9/07
Filed: 1921-08-26
Abstract: 193,437. Bonn, C. R. H. Aug. 26, 1921. Angular bending, curving, and straightening; mandrels.-In a machine for bending tubes or rods, the tube &c. is gripped at its rear part and pushed forward longitudinally so as to move a pivoted clamp which is secured to the tube &c. adjacent to the part to be bent, in the path of the bend. By reversing the operation the machine may be used for straightening bent tubes. The tube 14, Fig. 2 is secured by a. clamp 6 to the face 5 of a cylinder 4 which is traversed on a stationary hydraulic or like ram 3 mounted on a. sole plate 1. The clamp consists of jaws with stepped engaging shoulders which are held in position by a wedge 11 passing through a hooked binding strap 9 engaging behind interrupted flanges 10 on the cylinder. The sole plate, which is provided with a guide for the cylinder and with a bracket 21 for a screw adjusted interchangeable guide roll 19, is pivoted at 2 so that it may be adjusted to the radius of the bend and is secured in position by a screw-adjusted block 15. This block contains a slide 71, which may be moved by a hand-operated eccentric 17 so as to draw back the cylinder from the tube to facilitate removal thereof. The sole plate may be transversely adjustable in guides instead of being pivoted. The other end of the tube is secured in a clamp 24, adjusted by a screw 72, to suit the radius of the bend, in guides on a rod 30 carried by a radial arm 23 on a spindle 12. If desired, the spindle may be adjustable transversely instead of the sole plate. The clamp 24 consists of a pair of jaws which are mounted in guides in the limbs 27 of a bracket and secured by a wedge 26. The tube is supported by an internal mandrel, Fig. 7, the rod 31 of which is loosely mounted at 32 on the ram or sole plate. The head 33 projects beyond a line 35 passing through the axis of the roll 19. The loose mounting is provided so as to allow the head to follow the bend. In order to perform the bending operation, the cylinder is traversed on the ram so as to move the arm 23 on its axis 12. A modified clamp for preventing distortion of the tube has an extension 45, Fig. 8, on the inner side of the bend, having a rounded or bell-shaped mouth and a clearance space 48 between the points 49 and 50. For tubes of large diameter a mandrel may be inserted in the tube in the clamp. In one. form, Fig. 9, the mandrel consists of a split body 52 adjusted by a conical rod 54. In another form a ball headed mandrel is used, which may be connected to a plug by a rod or chain. In a modified form of bending machine, Fig. 16, an additional roll 62 is provided which is arranged to be moved round' the axis 12 either by the cylinder, by friction of the tube or other means. In another form, Fig. 14, the tube is guided by a fixed plate 60 and traversed by a hydraulic cylinder or other means. In a modification of this form, the plate is replaced by an abutment roll and may, if desired, also have a roll such as 62. In another form the tube is guided by a series of fixed rolls. According to the Provisional Specifications, the tube may be bent round a grooved former which is positively rotated, the rear end of the tube being clamped to a freely moving or positively moved slide or moving along a stationary guide. In a modification of the form in which a grooved former is dispensed with, the spindle carrying the arm of the pivoted clamp is positively driven by gearing in addition to the positive movement of the slide, the clamp being capable also of swivelling about an axis parallel with the spindle. A rotatable internal mandrel may also be used.