Metal bending apparatus

摘要

1,061,689. Bending. CASE INSTITUTE OF TECHNOLOGY. June 23, 1965 [June 23 1964], No. 26630/65. Heading B3E. [Also in Division G3] In a metal bending apparatus, Fig. 6, a beam 15 is supported between abutment posts 11, 12 and bent by a lug 14 of an hydraulic ram. The angle by which the beam has been bent is measured by a measuring system comprising digital photoelectric quantizers 24a, 24b mounted on angle sensors 29, 30 coupled by a rod 27 having a straight edge 28. The digital measurement from the quantizers is compared in a data system with the desired angle of bend and the ram controlled accordingly. The ram is then released, the spring- back measured and an increased angle of bend derived and applied. This procedure is repeated until the beam assumes a permanent angular deflection equal to the desired value. In a programme controlled system, Fig. 20, command data on a punched tape 159 is read into desired angle register 391 and the registers in multipliers 166, 162. Clock pulses are generated by a multivibrator 157 and enter at a rate determined by multiplier 166. The beam to be bent is advanced by a beam advancer 158 synchronized with the tape feed. The bending is measured by quantizers 24a 24b and the quadrature pulse trains are analysed by direction and sensing logic circuits 42a, 42b to derive from an anti-coincidence circuit 43 pulse trains representing the angular deflection of the beam. The pulse trains are fed to a rate limiting anti-coincidence circuit 44. The state of a bidirectional binary counter 451 represents the error in the control loop and through a digital to analogue converter 26 controls a valve 221 for an hydraulic actuator 13 so as to reduce the error to zero. The return of the actuator 13 is then initiated and the spring-back read as the count in an errorcounter 461. A pulse generator 161 reads the counter 461 and the pulse train, through a multiplier 162 set at a factor between 0 and 2 determined by experience, is fed to the register 391. A counter 167 determines the number of times the sequence of bending and determining apring- back is repeated. In an alternative arrangement the desired angle of bend is set up on dial switches and the sequence of bending and determination of spring back is carried out manually.