Automatic computation of bending sequences for double-head wire bending machines

Abstract

ABSTRACT Determining a feasible bending sequence for a double-head bending machine is a challenging and time-consuming task, even for an expert operator. An automatic bending sequence computation algorithm for a single-head bending machine was proposed in a previous work, exploiting A ⋆ graph search algorithm and the representation of the workpiece as an equivalent manipulator. This paper extends that approach to the case of a double-head bending machine, whose complexity, in terms of number of possible solutions to the problem of computing the feasible bending sequences, and of determination of the better sequences, that should exploit parallelism thanks to the execution of simultaneous bends on the two heads, is definitely higher. In this case, the wire has been modelled using two serial-link manipulators with a common base, and the A ⋆ cost function has been modified to promote simultaneous bends. An axes reachability-based path generator and the possibility of partial sequence search have been incorporated as well, to manage the run-time challenges due to an increased number of bends. In this way, an efficient bending sequence computation algorithm for a double-head wire bending machine has been devised, whose performance has been assessed on two industrial test cases, demonstrating its effectiveness and usefulness.