GB1275783A - Improvements in apparatus for twisting concrete-reinforcing bars - Google Patents

Abstract

1275783 Twisting; tensioning RHODEN PARTNERS Ltd 12 Nov 1970 [14 Aug 1969] 40787/69 Heading B3E Apparatus for twisting and tensioning metal bars for concrete reinforcement includes a tailstock a head stock and a reciprocable carriage 25 having an opening for receiving one end of an untwisted bar 66 and power-operated clamping means to grip said one end of the bar and to maintain such grip after completion of the twisting until the carriage has been partly retracted when a stationary abutment 17 engages a spring-loaded ejector rod 34, 39, which during the last part of the advance movement of the carriage pushes the bar forward to introduce the other end into the headstock and during the last part of the retraction of the carriage the ejector having been brought to rest by the abutment will engage the twisted bar and eject it from the apparatus by preventing it from continuing to move back with the carriage. The abutment 17 is mounted on an end frame 16 and the carriage 25 is slidable on guideways 19, 21 and 22 and reciprocated by a double acting hydraulic cylinder 17. The spring 45 of the ejector rod is protected from scale by a bellows 46. A funnel guide 50 is bolted on the front end plate 29 of the carriage and behind this is located a fixed jaw block 49. Mounted beneath this fixed jaw is a pivoted lower jaw 56 actuated by a double-acting cylinder 63 fixed to the near end wall of the carriage. Fixed to the front end of the lower jaw 56 is a member 58 which forms a segment of the funnel guide 50. In operation the carriage is advanced so that a bar 66 is fed through the funnel 50 (Fig. 1) and brought into engagement with the ejector rod which pushes the bar into the headstock (not shown) and the carriage is halted by a microswitch (not shown) which stops the power cylinder 27. The cylinder 63 is now activated to clamp the end of the bar and at the same time the other end of the bar is gripped in the headstock. The tailstock is then retracted to tension the bar and the headstock rotated to twist the bar. After this operation the headstock releases the bar and the carriage is retracted and the clamping jaws released so that the ejector rod pushes the treated bar from the tailstock when the rod engages the abutment 17. An alternative form of tailstock carriage is shown in Fig. 4 wherein the gripping means comprises upper and lower jaw blocks 73, 72 connected by parallel links.