Analysis and optimization of traveling wave vibration of large diamond thin-wall drill bits
Objectives:To reduce the vibration and noise generated by thin-walled drill bits during the drilling and cut-ting process,various designs of thin-walled drill bits were studied,including conventional thin-walled drill bits,open-hole thin-walled drill bits,open-hole and interlayer thin-walled drill bits,and thin-walled drill bits with positioning wheel.The reasons for vibration and noise reduction of thin-walled drill bits in different schemes were analyzed at a the-oretical level.A new scheme for thin-walled drill bits was proposed,which exhibited good vibration reduction effects,protected the hearing of thin-walled drill bit operators,and complied with China's environmental indicators for workers.Methods:Modal analysis and traveling wave vibration analysis of thin-walled drill bits were performed using Work-bench software to study the effects of different thin-walled drill bit designs on traveling wave vibration.First,a solid work model of the thin-walled drill bit was imported into Workbench software and meshed.The inner hole of the thin-walled drill bit was constrained(cantilever type),and the first 30-order modes of the thin-walled drill bit were calcu-lated under standard earth gravity.Using traveling wave vibration theory,the δ value of the resonance margin of the thin-walled drill bit in different schemes was calculated to determine the effectiveness of avoiding traveling wave resonance.Results:At a drilling speed of 187.32 r/min,the conventional thin-walled drill bit had a δ value of 0,leading to rear traveling wave resonance.The opening of 8 groups of round holes and 8 S-hole thin-walled drill bits had a δ value of 5.18%,which was the best opening design scheme.Further interlayering the thin-walled drill bit resulted in a δ value of 6.11%,showing the best effect in avoiding traveling wave resonance.In the δ where 2 to 12 positioning wheels thin-walled drill bits were installed,the δ of 2,3 and 11 positioning wheels thin-walled drill bits was less than 1.00%,effect-ively avoiding traveling wave resonance.Conclusions:Thin-walled drill bits with traveling wave resonance will pro-duce strong vibration and noise.Reducing the deformation of the thin-walled drill bit increases the δ value,leading to better vibration and noise reduction.To ensure the precision of the drilled hole,the positioning theory was applied to the thin-walled drill bit.When comparing δ values for drill bits with 2 to 12 positioning wheels,the designs with 6 and 12 positioning wheels had larger δ values and better vibration damping effects.Considering installation convenience,6 pos-itioning wheels were determined to be the optimal number,providing a theoretical basis for reasonable determination of the number of positioning wheels.
diamond thin-wall drill bitsopening and interlayerpositioning wheeltraveling wave vibration
万方数据
维普
