Research On Compression Method Of Multi-axis Machining Trajectory Based On Double B-spline

Multi-axis machining program is usually composed of G01 small line segments.The adjacent small line segments only achieve G0 continuity,and each small line segment is short,which will lead to the discontinuity of speed and acceleration and low machining efficiency.Therefore,many researches use double spline to compress the tool tip and tool axis of multi-axis tool path respectively.However,due to the complexity of multi-axis machining trajectory,there are still many problems worthy of study in multi-axis trajectory compression,including high efficiency and high compression ratio dual spline trajectory compression,error calculation of compressed dual spline trajectory,construction of parameter synchronization relationship between dual splines,and fairing of singular regions.Based on these problems,this thesis proposes a set of multi-axis trajectory compression method,which mainly includes the following research contents:(1)according to the different processing characteristics of reduced material manufacturing and additive manufacturing,this thesis proposes the tool position error calculation methods of these two processing scenarios,and unifies them into the compression error calculation model of double spline trajectory,so as to adapt to the error calculation in different processing scenarios.(2)In order to construct the parameter synchronization relationship between two spline trajectories,this thesis uses the monotone non decreasing C2 continuous rational quadratic spline to interpolate the node vectors of two spline trajectories to construct the parameter synchronization relationship between two spline trajectories,and ensures that the rotation axis motion of two spline trajectories can achieve acceleration continuity.(3)Aiming at the problem that the small segment program can only achieve G0 continuity,an adaptive interpolation trajectory compression method is proposed in this thesis.By compressing the small segment program into double cubic non-uniform B-spline,the multi-axis machining trajectory can achieve C2 continuity.At the same time,it also achieves high compression ratio,high compression efficiency,trajectory does not have double points,and velocity continuity in singular region.Finally,a multi-axis trajectory compression software module is developed in the off-line environment,which can efficiently generate the multi-axis machining trajectory of double B-spline according to the input tool position and compression parameters.In order to verify the effectiveness of the algorithm,this thesis carries out the simulation verification and actual processing verification;simulation results show that the algorithm can compress multi-axis tool path into C2 continuous double spline trajectories with high compression ratio;the actual processing verification results show that the algorithm studied in this thesis improves the processing quality of parts,and is suitable for industrial processing.