Spiral Scanning Path Generation And Verification For Free-form Surface Five-axis Inspection

In various manufacturing processes,it is very important for quality assurance and other factors to measure the geometric information of parts.This requires obtaining the geometric information of free-form surfaces in a high-precision and efficient way.Traditional inspection of freeform surfaces via three-axis or three+two-axis CMM mainly works in a point-by-point manner where for each inspection point,the stylus of CMM has to approach to and then retract from the surface of inspection,which inevitably drags down the inspection efficiency.Recently,a new inspection apparatus called five-axis inspection machine has emerged,on which the stylus tip can continuously sweep on the part surface and the inspection efficiency can thus be tremendously improved.The crux in using this new inspection technology is how to plan an efficient five-axis inspection path.For the five-axis inspection path of freeform surface,some research schemes at home and abroad usually need to partition the surface first,and then generate five-axis continuous scanning path on each area respectively.This has limitation.In the process of inspection,the probe needs to move between each partition.The transition between each partition will lead to the improvement of non-inspection time and affecting the improvement of measurement efficiency,thus affecting the improvement of measurement efficiency.In addition,the more the transition area,the interference and collision between the probe and the surface to be measured are easy to occur,resulting in the failure of inspection.To solve this problem,in this paper,we present a new type of five-axis inspection path generation strategy.By using harmonic mapping technology,the transformation between surface domain and parameter domain can be realized.Based on the phenomenon of oversampling,the relationship between surface width and scanning efficiency is discussed.and the concept of surface scanning rate(SSR)is proposed,which represents the efficiency of scanning different width surfaces.In order to maximize the SSR,the iso-parametric sequence determination(ISD)algorithm is designed.The best contour of the surface with the highest scanning rate is selected.Then the concept of spiral transition is introduced.All the best contour lines are smoothly connected into a spiral curve.The surface is covered by a spiral belt,and the surface is divided into a single spiral area,which not only maximizes the overall surface scanning rate,but also avoids the partition of the surface.And for this single spiral strip,by using the theory of five-axis inspection path generation introduced,a complete five-axis spiral scanning path is generated,which takes into consideration the key constraints such as the required smoothness of the probe head trajectory,the sampling density,and the collision-free condition.Finally,physical inspection experiments of our proposed strategy are conducted on two typical freeform surfaces.Compared with the measurement results of two popular scanning strategies.The results convincingly confirm the feasibility,effectiveness,and advantages of our new solution.