水射流辅助硬质合金钻头切割岩石过程的刀具温度分析

Temperature analysis of cemented carbide drill cutting rock associated with water jet

通过对硬质合金钻头切削岩石过程中热量转换、传递过程分析,建立了前刀面的温度方程。根据对水射流与刀片间传热过程的热力学分析分别建立了水射流与刀片表面对流换热微分方程组和热源与刀片间的稳态导热微分方程,推导出水射流对刀片的换热功率表达式和刀片内温度场表达式。研究表明,在无水射流情况下,钻头切削岩石前刀面温度变化与切削速度vq的平方根成正比;水射流的存在可以大幅降低刀具的温度,水射流对刀片的换热功率Φ与射流压力p的四次方根成正比,刀片平均温度的变化与p-1/4成正比。一定条件下的试验结果表明,采用水射流辅助硬质合金钻头切削岩石,当射流大于适当压力,钻头破损程度大幅下降,从而有效地提高钻头寿命。

The temperature equation of drill rake face was established upon the analysis of heat conversion and transfer during the rock cutting process which uses cemented carbide drill bit. Based on the thermodynamic analysis of heat transfer process between water jet and the blade surface,the differential equations of heat convection and differential equation of steady heat conduction between water jet and the blade surface were established. Expression of heat exchange power and expression of temperature field of the blade were derived. Study results show that without water jet,the temperature of the drill rake face in rock cutting is proportional to the square root of cutting speed vq,and the existence of water jet can significantly reduce the temperature of cutting tool,the power expression of heat exchange Φ between water jet and the blade surface is proportional to the four square root of the jet pressure p,the average changing temperature of blade is proportional to p-1/4. The experimental results under certain conditions show that the drill breakage declined sharply and the life of drill is improved effectively by cemented carbide drill cutting associated with water jet.