GB1470290A - Bar bending machine - Google Patents

Abstract

1470290 Bending EVG ENTWICKLUNGSU VERWALTUNGS-GmbH 26 Nov 1975 [16 Dec 1974] 48652/75 Heading B3E A bar bending machine controlled by a programme control device comprises a stationary mandrel 1, a bending tool 3 swingable about the mandrel, and a clamping device 25 upstream of the mandrel along a bar feed path, to prevent the bar from twisting about its axis during bending, e.g. in the case of bar having helically arranged ribs. In the figure, bending is effected by a jack 4, and a movable clamp element 11 is forced against a fixed clamp element 10 by jack 13, the piston of the latter having a larger cross-section than that of jack 4. The fixed clamp element 10 may serve also as the fixed element of a bar shear device. The two jacks may be controlled by a single electrohydraulic valve 20 as shown, or by separate valves. On completion of the bending step, the bar may be advanced for shearing to length or for a further bend. An alternative bending mandrel may be disposed on the other side of the bar feed path, the tool 3 being disposable and actuable to bend the bar about the alternative mandrel in the opposite direction to that shown. The tool 3 may have an arcuate or V-section groove. Engagement of a stop 80 adjustably mounted on the rod 98 with the ring 88 stops movement of the tube towards the cutter and engagement of a stop 82 adjustably mounted on the rod 98 with a ring 90 controls retraction of the support 64 on which the grippers are mounted and which is secured to the support 86 of stop 82. The distance between stop 82 and ring 90 determines the length of tube to be fed over the cutter 54. In use, while the tube is fed towards the cutter, the cutter unit is fed towards the tube as far as stop (121), Fig. 1 (not shown), will allow, by an hydraulic cylinder (118). A clamp 100 is drawn down by an hydraulic cylinder 106 to clamp the tube against member 102 during shearing. The clamp members are spaced from jaws 58, 60 by 90 degrees and the gripper 60 is disengaged from the tube before the clamp 100 is applied to the tube. The cylinder 30 is actuated to pivot the arm 22 downwardly so that the cutter 54 indents the tube, Fig. 7. The shaft 36 is then rotated through a onerevolution clutch to cause the cutter 54 to roll round the whole inner periphery of the tube to shear off an end portion against an annular cutter. An electrohydraulic system for automatic operation of the device includes a limit switch which has to be contacted by a falling sheared-off end portion before another shear cycle is initiated.