摘要
针对大型金刚石薄壁钻头在钻切中出现的振动和噪声问题,用Ansys Workbench有限元软件对无开孔、开孔、开孔且夹层和安装定位轮的薄壁钻头进行模态分析,进一步用行波振动理论计算薄壁钻头共振裕度δ,分析避开行波共振的效果,研究开孔、夹层对行波振动的影响.结果表明:钻切转速为 187.32 r/min时,无开孔薄壁钻头的共振裕度δ为 0,出现后行波共振;在无开孔薄壁钻头出现后行波共振固有模态变形大的区域开 8组圆孔(每组 3个)和 8个S形孔,薄壁钻头的共振裕度δ为 5.18%,避开行波共振效果良好;开孔且夹层的薄壁钻头的共振裕度δ为 6.11%,避开行波共振效果最好.为提高孔的加工精度,在薄壁钻头周围安装定位轮,分析定位轮数对行波振动的影响,发现安装 6个和 12个定位轮的薄壁钻头的共振裕度δ分别为4.59%和 4.79%,避开行波共振效果好.比较 2～12个定位轮薄壁钻头的共振裕度δ,而且考虑安装方便,最后确定最佳安装定位轮数为6个.
Abstract
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.
维普
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