受力分析在牙轮钻头失效分析中的应用

Application of Mechanical Analysis to Roller Cone Bit Failure

文章将物理学中的受力分析应用于KX84系列牙轮钻头的牙爪大跑道的失效分析。首先,文中基于“压力-压强”转换,根据轴压确定了牙轮钻头系统所承受的压力。其次,根据“切向力-法向力”分解,对牙轮钻头所受的压力进行受力分解,确定了牙爪大跑道所承受的压应力。最后,对切应力进行分析,确定了裂纹萌生的范围。结合相关数据发现,KX84-250牙轮钻头和KX84-310牙轮钻头裂纹萌生深度分别为0.7 mm(计算结果为0.45 mm~0.78 mm)和0.85 mm(计算结果为0.57 mm~0.98 mm),计算结果与实际观察结果相符。文中给出的案例对物理教学和失效分析都有促进作用。

In this paper,the mechanical analysis in physics is applied to the failure analysis of the raceway of leg of KX84 series roller cone bit.Firstly,based on the analysis of pressure-force transformation,the force of the roller cone bit system is determined according to the axial pressure.Secondly,according to the decomposition of tangential force and normal force,this paper decomposes the pressure on the roller cone bit,determines the compressive stress on the raceway of the leg.Finally,the maximum 45°shear stress(τ45°max)is analyzed to determine the range of crack initiation.It is found that the crack initiation depth of KX84-250 roller cone bit and KX84-310 roller cone bit are 0.7 mm(calculated result 0.45 mm~0.78 mm)and 0.85 mm(calculated result 0.57 mm~0.98 mm),respectively.The calculation results are consistent with the actual observation results.The case in this paper can promote physics teaching and failure analysis.