Harmonic Drive Design And Harmonic Response Analysis Based On Borehole Trajectory Control Tool

Borehole trajectory control tool is a new type of drilling tool with stepless-adjusted directive rotary steering.In the process of borehole trajectory control tool,the reducer with high transmission accuracy,large transmission ratio and strong bearing capacity is required to ensure the control accuracy of the tool and improve the precision of downhole positioning.The harmonic drive with ring flexspline can effectively solve the problems of difficult processing of cup-shaped and short cup-shaped flexspline reducer,as well as stress concentration in the corner of cup bottom,but also has the advantages of small size,light weight,compact structure,long life and so on.Therefore,the harmonic drive with ring flexspline is taken as the study object in this paper,fully considers the particularity of the borehole trajectory control tool’s working environments,and focuses on the mechanical properties of the flexspline which is prone to fatigue failur in the harmonic drive.It provides a reference for the design of harmonic drive to meet the borehole trajectory control tool’s requirements and a necessary theoretical basis for the design of harmonic design in the related field.Through a large number of literature research and analysis,it is concluded t hat the harmonic drive with ring flexspline can better meet the requirements of t he borehole trajectory control tool to bear a large load.The harmonic drive desi gn theory is applied to the structure design of harmonic drive components,the fl exspline,the circular spline and the wave generator.The material of each compo nent is decided,and the theoretical strength of the designed harmonic drive is ch ecked.The finite element software ANSYS Workbench is used to analyse the dis tribution of the flexspline’s assembly stress and deformation,and their distributio n laws after assembly are further obtained.By changing the single structure para meter of ring flexspline,the maximum radial deformation,length-diameter ratio,gear ring’s wall thickness or gear ring front & rear edge width,the influence rul es of different parameters on ring flexspline’s stress and deformation under no-lo ad and rated load are calculated and obtained.In order to obtain a ring flexspline structure with better mechanical propertie s,improving the service life of harmonic drive,it takes ring flexspline’s maximu m stress under rated load as the evaluation index,the ring flexspine’s four struct ure parameters as the influencing factors of the orthogonal test.The four structur e parameters are the maximum radial deformation,length-diameter ratio,gear rin g’s wall thickness,gear ring front & rear edge width.Then,the sensitivity order of the four structure parameters on flexspline’s stress is gear ring’s wall thicknes s > maximum radial deformation > gear ring front & rear edge width > length-d iameter ratio,and the ring flexspline’s stress is reduced by selecting the optimal structural parameters.Since the harmonic drive is applied in the borehole trajectory control tool,v ibration and shock will be generated during the work.Therefore,the natural freq uency analysis and harmonic response analysis of the optimized harmonic drive a re carried out.The results show that the harmonic drive will not resonate in the rest state or working state.