斜轧穿孔机顶杆弯曲挠度及临界失稳力计算分析

Calculation analysis on mandrel bending deflection and critical unstable force for rotary piercing mill

通过对斜轧穿孔过程中顶杆受力和运动约束进行分析,依据相关力学理论建立了顶杆临界弯曲失稳力和弯曲挠度分布计算模型。顶杆抗失稳能力随其直径和定心装置套数的增加迅速提高,随其长度的增加而减弱。顶杆最大弯曲挠度随顶杆阻力及顶杆长度的增加而增加,随其直径的增加而减小。在压力机上进行了压杆弯曲实验,证明了顶杆失稳弯曲变形不对称,当顶杆未安装定心装置时,最大弯曲挠度发生在距顶头端1/3顶杆长度位置;提出了在顶杆弯曲最大挠度点安装定心装置的新方法,可减少必需的定心装置套数并提高抗失稳能力。研究结果有助于预测顶杆失稳和确定定心装置套数及位置。

By analyzing the force and movement constraints of the mandrel during rotary piercing process,the calculation model of the distribution of critical bending unstable force and bending deflection of the mandrel was established based on the relevant mechanics theory. The stability resistance of the mandrel increases rapidly with the increase of mandrel diameter and the number of centering device sets,and decreases with the increase of the mandrel length. The maximum bending deflection of mandrel increases with the increase of the resistance and the mandrel length,and decreases with the increase of the mandrel diameter. The compression mandrel bending experiment was conducted on pressure machine,and the bending deflection deformation was confirmed to be asymmetric. The maximum bending deflection appears was one third of the mandrel length when none of the centering device is installed. A new method to install a centering device at the position where the maximum bending deflection appears was proposed which can satisfy the purpose of saving the number of centering device sets and improving the ability of unstable resistance. The research results can provide credit help for predicting mandrel instability and determining the number of centering device sets and the installation positions.