锚杆尾部螺纹加工精度对预应力影响的实验研究

Experiments on effects of thread rolling accuracy on rock bolt pretension

在研究螺母扭矩与锚杆预应力关系的基础上,分析螺纹加工精度对锚杆预应力的影响,及影响螺纹加工精度的主要因素,包括锚杆材质、加工工艺与设备。专门设计了螺纹扭矩与锚杆预应力关系实验台,对采用国内外不同工艺与设备加工的锚杆试件进行了螺纹扭矩与预应力关系试验。实验得出:螺纹精度越高,消耗在摩擦力上的扭矩越小,扭矩转化系数越高;在螺纹上涂润滑油可提高扭矩与预应力的转化系数。我国现有锚杆螺纹加工精度低,表面粗糙,存在较多加工缺陷,不利于螺母扭矩转化为预应力,同时引起锚杆损伤与破断。解决这些问题的根本方法是采用先进的锚杆螺纹加工设备,优化加工工艺,提高螺纹加工精度。

Based on analysing the relation between the nut torsion moment and rock bolt pretension,the influence of the thread rolling accuracy upon the pretension was investigated.Factors influencing the thread rolling efficiency,i.e.,rock bolt material quality,rolling technology and equipments,were examined.To study the relationship between torque and pretension,a laboratory table was specially designed and a series of tests were carried out on the rock bolts with different thread accuracy.The result indicates that the higher the thread rolling accuracy,the higher the coefficient of torque-to-pretension conversion.And the coefficient can be improved by daubing lubrication oil on the thread.In China,the rock bolt thread encounters the issue of low rolling accuracy which results in coarse thread surface.As a result,the efficiency of the torque-to-pretension conversion is greatly reduced.In addition,the rock bolt is susceptible to break at the thread end.Essential approach to resolve these issues is to significantly improve the thread rolling accuracy by adopting advanced equipment.