Experimental Study On Motion Law Of Planetary Drilling Bit

In the field of underground engineering construction,drilling large diameter shaft usually adopts the method of one advance and multiple reaming.The rock-breaking method of drilling bit is mainly rolling and crushing,and the tool generates concentric circle track on the working surface.In order to drill larger diameter shaft,if we develop larger diameter powerful drilling rig,we will have higher requirements for drilling power,volume,drill pipe strength and tool life.Therefore,in order to adapt to the development of the times and improve the support ability of drilling engineering technology,it is necessary to further explore large diameter drilling engineering technology and study other structural forms of large diameter drilling rigs.Planetary bit is a rock-breaking bit structure consisting of a central gear and several planetary gears.The central gear shaft is connected with a leading bit.Each planetary gear is connected with a cutter head on the planetary shaft.The planetary gear train drilling equipment can be formed with the drilling rig.The cutter generates cycloid trajectory on the working surface.The rotary moment required by planetary gear train drilling rig is much smaller than that of conventional drilling rig with the same diameter,and the cross section with larger diameter can be broken by smaller cutter head.In this paper,a mathematical model of planetary bit is constructed.Taking the size and motion parameters of the bit as variables,the mathematical trajectory curves of a single tool on the cutter head of a plane univariate and bivariate bit are solved,and the spatial trajectory curves of the mathematical trajectory of a single tool on a non-planar planetary bit with bevel gear structure and other cutter trajectory curves on the cutter head are derived.Based on the cutter trajectory curve of planetary bit,the formation of the cutter trajectory of planetary bit is analyzed by combining theoretical analysis,numerical simulation and model experiment.The structural parameters of planetary bit include transmission ratio,axis intersection angle of transmission gear and deviation of cutter layout radius.At the same time,the cutter trajectory of planetary bit is analyzed and studied.The cutter motion parameters include cutter velocity and movement.The influence of the dynamic deviation angle on the motion law of the bit is analyzed,and the curves of the tool velocity and the deviation angle of the planetary bit with time are obtained.The motion trajectory equation of planetary bit cutter and the motion law of dischob on the bit obtained in this study have a strong reference value for further studying the structure of planetary bit and applying planetary bit to engineering practice.