| Mirror milling system(MMS)is used for processing large thin-walled workpiece,which controls the multi-axis machine tools cooperate on both sides of the workpiece in the form of the master-slave dual channel cooperation mode.Ensuring the safety and efficiency of collaborative processing between master and slave channels requires the combination of processing technology and velocity planning.The existing MMS lacks a safe processing technology that can be followed,and the master-slave velocity planning method also has the hidden danger of incomplete consideration of constraints.To solve the above problems,this paper studies the safe synchronous processing technology of MMS and the velocity planning method under multi-constraints.Aiming at the security problem caused by establishing of synchronous relationship in MMS asynchronously,a MMS processing technology and a corresponding NC code format specification of dual channel tools feed or withdraw safely are designed to ensure the orderly execution of dual channels in the asynchronous segment and the cooperative processing in the synchronous segment.To solve the defects of the master-slave velocity planning method,an off-line verification and correction process of velocity planning is designed to realize the indirect correction of the system velocity planning by the external NC codes.Based on the difference of dual-channel motion performance in MMS,a multi-constraint with additional consideration of slave channel’s constraints is proposed,which solve the original system’s incomplete constraints consideration.Aiming at the situation that the slave channel doesn’t plan the velocity actively,accorded to the theory of master-slave velocity planning,this paper proposes a technique to calculate slave channel’s motion data according to master channel’s velocity planning,which solves the problem that slave channel lacks of data during the dual-channel velocity verification.Based on the features of mirror milling path,the rules of selecting intervals of velocity planning to be verified is given,which can accurately recognize multiple over-limit intervals.To correct multiple over-limit intervals of the MMS’s velocity planning,an iterative calculation method for searching the safe velocity in these over-limit intervals under restrictions of dual-channel multiple constraints is designed,which can effectively deal with various types of over-limit situations.The newly generated NC code assists the CNC system to generate a safe and efficient new velocity planning,which solves the problem that various motion parameters of the dual-channel exceed the constraints during the mirror milling.Finally,the post-processing software of MMS is developed,which meets the dual-channel feed or withdraw safely requirement.Simulation shows that processing technology can eliminate the unsafe asynchronous movements of MMS.The off-line verification and correction function module of MMS velocity planning is developed.The running results before and after correction are obtained by using the simulation system of MMS.The comparative experiment results confirm the validity of the method proposed in this paper,dual-channel in MMS now can machine safely. |
