Fig. 3

Schematic diagram of situation 3: This figure is the schematic diagram of the interchange when the pre-tightening process is a multi-device process and the post-tightening process is a common process. First of all, cancel the scheduling of all parallel sub-processes contained in process B. Then process A is rescheduled, compare the maximum finishing time of all processes in the pre-tightening process set of process A in the processing process tree with the finishing time of the pre-tightening process set of process A on its processing device; the maximum of all the above times is set as the processing start time of process A. Then process B is rescheduled, and the finishing time of process A is, respectively, taken as the starting time of each parallel sub-process in process B