磨料水射流冲击角对砂岩切割性能影响的试验研究

Experimental study on the effect of abrasive water jet impact angle on the cutting performance of sandstone

磨料水射流是一种高效的切割技术,通过砂岩切割试验对岩石类材料的最佳冲击角和倾斜切割机理等问题展开研究,在对切缝内壁进行宏观和微观观测的基础上,开展水晶玻璃切割试验,探究不同冲击角下磨料水射流的切割运动过程,揭示了不同切割压力及冲击角下的切缝深度、切缝内壁特征、磨料颗粒运动轨迹与晶体破坏类型等变化规律。试验结果表明:平均切缝深度随切割压力的增加逐渐增大,同时改变冲击角能明显改变射流的切割能力,在75°冲击角获得的切割效果最佳;随切缝深度增加在切缝内壁逐渐出现弯曲射流轨迹纹理,且在其底部均形成典型的冲蚀坑与拖尾现象;切缝内壁主要表现为穿晶断裂、沿晶断裂、切槽或凹坑、胶结物覆盖等4类破坏特征,值得注意的是,不同冲击角下4类破坏特征在切缝中出现的位置不同,该种现象主要是因为射流的偏转情况、反射流的运动方向、冲击波和膨胀波的反射作用改变;对靶件破坏起主导作用的是垂直向及水平向射流分量(与推进方向同向),与推进方向反向的水平向射流分量则对已形成切缝起二次冲蚀及抛光作用,但不同冲击角下的作用程度不同;结合切缝表面观测和射流切割过程观察结果,建立了磨料水射流切割过程的宏观模型。

Abrasive water jet is a highly efficient cutting technology.Through some sandstone cutting tests,the research on the optimal impact angle and inclined cutting mechanism of rock-like materials is carried out.Based on the macroscopic and microscopic observation of the cut’s inner wall,crystal glass cutting experiments are conducted to investigate the cutting motion process of abrasive water jet under different impact angles,revealing the variation laws of cutting depth,the characteristics of the cut’s inner wall,the trajectory of abrasive particles and the type of crystal destruction under different cutting pressures and impact angles.The test results show that the average cutting depth gradually increases with the increase of cutting pressure,while changing the impact angle can significantly change the jet’s cutting ability,and the best cutting effect is obtained at an impact angle of 75°.With the increase of the cut depth,the curved jet trajectory texture gradually appears in the cut’s inner wall,and in its bottom there are typical erosion pits and trailing phenomenon.The cut’s inner wall is mainly characterized by four types of damage features such as fracture through the crystal,fracture along the crystal,cut grooves or pits,and cement coverage,etc.It is worth noting that the four types of damage features appear at different locations in the cut at different impact angles,and this phenomenon is mainly caused by the deflection of jet,the direction of reflected flow movement,and the change in the reflection of shock wave and expansion wave.The vertical and horizontal jet components(in the same direction as the direction of propulsion),which play a dominant role in the destruction of the target,and the horizontal jet component,which is opposite to the direction of propulsion,play a secondary role in the erosion and polishing of the formed cut,but the degree of action varies under different impact angles.The macroscopic model of the abrasive water jet cutting process is established by combining the trajectory texture of cut’s inner wall and the observation results of the jet cutting process.The research results can provide a technical reference for further improving the efficiency of abrasive water jet cutting.