Zhao Chunjiang

Analysis of bearing characteristics of axially heavy-loaded composite nut

A three-dimensional solid model is constructed for the heavy-loaded screw pairs of a nut subjected to axial compressive load and thrust on different sides. The finite element software ANSYS is used to calculate the stress and strain distribution at each thread root of the screw pairs. A composite nut structure is proposed based on the characteristics of the stress and strain distribution. This structure improves the local rigidity of the nut. The finite element method is adopted to calculate the stress and strain distribution at each thread root of the composite nut. The comparison of the measured results and calculated results indicates that the maximum stress and strain at the thread roots of the composite nut decrease significantly while the load distribution becomes considerably even. An experiment is conducted to check the calculated results for the two types of screw pairs. The experimental results verify the appropriateness of the composite nut structure.

Finite element analysis and structural design of axially uniform-loaded nut:

Axially heavy-loaded screw pairs are widely used in rolling mill press systems and other heavy equipment. During the working process, the nut is pressed at both ends, which causes equivalent stress at the thread roots in a U-shaped distribution along the height. Thread roots at the ends tend to suffer fracture failure when the equivalent stress is too great. In this article, the finite element software ANSYS is used to establish a 3D model of screw pairs and analyse bearing characteristics. A new structure based on the results of finite element analysis, which improves U-shaped stress distribution, is proposed for the axially uniform-loaded nut, with a different strain–displacement relationship between the nut matrix and the thread teeth. Such a relationship can greatly reduce peak stress at the thread roots of the nut on both ends. Experiments are conducted on the nut using the electrometric method. Results are compared with the finite element results to directly verify the reliability of the finite element model of ordinary screw pairs and indirectly verify the reliability of the structural model of new screw pairs.