水射流辅助岩石切削过程的刀具热应力分析

Thermal stress analysis of tool in cutting rock with water jet

建立了刀片在水射流辅助切削岩石过程中的热传导模型,并在对岩石切削过程进行热功转换分析的基础上,给出了热流密度、界面温度等边界条件的确定方法,从而建立了水射流条件下刀片的温度场模型。对刀片由于温度变化产生的热应力进行了系统分析,并给出了热应力的计算模型,并且结合计算分析了射流压力等参数对各种热应力的影响。研究表明:热应力是导致岩石切削刀具失效的主要影响因素。热应力受刀具与岩石材料热物性质、刀片尺寸、切削力、切削速度、射流压力等因素影响。水射流的存在可以大幅降低刀具的热应力,热应力的大小与射流压力p的四次方根的倒数成正比。选择合适参数可将热应力控制在临界范围内,避免刀具早期失效,延长其使用寿命。

Heat conduction model of the blade of tool was established during the process of rock cutting with water jet.Based on the analysis of the conversion between thermal and power in rock cutting,computational methods of the boundary conditions such as heat flux,interface temperature were given.Thereby the temperature field model of the blade was established in rock cutting with water jet.The thermal stresses of drill bit were analyzed and computational models of the thermal stress were also presented.The influence of parameters to the thermal stresses such as jet pressure was analyzed and computational methods were also given.The results show that thermal stresses are the main factors which induce the tool failure.The thermal stresses are influenced by material properties of the tool and rock,blade sizes,cutting force and speed,jet pressure.The thermal stresses of drill bit can be decreased efficiently by water jet and it is proportional to the reciprocal of four square root of the jet pressure.The life cycle of the tool will be prolonged without earlier failure if the parameters are controlled in critical range.