Rotation of point attack picks in their tool holders is of crucial importance for an efficient performance of machines used for tunnelling and underground excavations of rocks and coal. With current machines, skew angle has been extensively employed to achieve tool rotation. There has, however, been no common definition and suggestion on application of skew angles, due to the differences between the results of research investigations conducted in this field. This paper sets out the findings of long-term practical research during tunnelling and underground excavation operations with roadheaders and drum shearers in order to bring a common understanding in rotation of point attack picks. Mechanism of tool rotation was discussed, and a number of formulas were derived and suggested for optimum cutting conditions for roadheaders and mechanical miners, respectively. The results showed that with drum shearers tool rotation is possible without skew angles, due to the asymmetry between adjacent grooves which generates sideways forces inducing rotative movement of picks. Skew angles were, however, found to be a must for roadheaders in consideration with tool holder damage which was significantly influenced by different settings of skew angles. Furthermore, point attack picks with small-diameter shanks were found to suffer from shank breakage resulting from high values of tool forces, when fitted on the nose portion of roadheaders cutting heads.

尖头截齿在其刀架中的旋转对于岩石和煤炭的隧道掘进和地下挖掘所用机器的高效运行至关重要。在当前的机器中，倾斜角已被广泛采用以实现工具旋转。但是，由于在该领域进行的研究调查结果之间存在差异，因此对于偏斜角的应用尚无共同的定义和建议。本文阐述了使用掘进机和鼓式采煤机在隧道和地下挖掘作业中进行长期实践研究的结果，以便对点攻击镐的旋转产生共识。讨论了工具旋转的机理，并推导了许多公式，并为掘进机和机械矿工的最佳切削条件提出了建议，分别。结果表明，使用鼓式采煤机，由于相邻凹槽之间的不对称会产生侧向力，从而引起镐的旋转运动，因此可以实现无偏角的工具旋转。但是，考虑到刀架的损坏，斜角对于掘进机来说是必须的，而刀架的损坏会受到不同设置的斜角的明显影响。此外，当将小直径刀柄的尖齿镐安装在掘进机截割头的鼻部时，由于工具力值高而导致刀柄断裂。被认为是掘进机必须考虑到的刀架损坏问题，而刀架损坏受到不同偏角设置的影响。此外，当将小直径刀柄的尖齿镐安装在掘进机截割头的鼻部时，由于工具力值高而导致刀柄断裂。被认为是掘进机必须考虑到的刀架损坏问题，而刀架损坏受到不同偏角设置的影响。此外，当将小直径刀柄的尖齿镐安装在掘进机截割头的鼻部时，由于工具力值高而导致刀柄断裂。