Fig. 2

Schematic diagram of situation 2: This figure is the schematic diagram of the interchange when the pre-tightening process is a common process and the post-tightening process is a multi-device process. First cancel the scheduling of process A and then reschedule B, compare the maximum finishing time of all processes in the pre-tightening process set of each parallel sub-process included in process B in its process tree and the finishing time of the pre-tightening process on its device, respectively. The maximum of all the above times is set as the processing start time of process B. Then process A is rescheduled, and the finishing time of process B is taken as the starting time of process A