Analysis on the Thermal Stress of Brazed Diamond Bit during Cooling Process

摘要

Brazed diamond process is a new green manufacturing technology, and metallurgical bonding with the mixed chemical bond in the transition layer can be achieved between the diamond grits and its matrix. The high brazed temperature (970-1050 °C) and the expansion coefficient difference between the matrix and moulds cause thermal stress harm to the bit quality during cooling. To study the brazed diamond bit, a thermal elastic mechanics model of the matrix and the graphite mould was built based on the analysis of cooling process. The radial and tangential thermal stress between the matrix and the core mould were obtained. The study is shown as follows: the radial stress and the tangential stress approximate to a linear relationship with the temperature difference and the expansion coefficient difference. The thinner the matrix thickness becomes, and the greater the tangential stress increases obviously. Generally, the radial stress is smaller than the tangential stress for the special bit.