Residual Stress Field Analysis Of Monolayer Brazed Diamond Tools

The researches on the residual stress field of monolayer brazed diamond tools are very important, because they can make for controlling the natural quality of brazed tools, discriminating diamond damage, evaluating thermal distortion and adjusting brazing process to improve the machining capability. But the particularity and complexity of monolayer brazed diamond tools has blocked the analysis of the residual stress. On the condition of reasonable premise, only the mismatch of thermal and mechanical properties is concerned in this paper. By the means of the finite element analysis (FEA) modeling, the change of thermal field and stress field from high temperature to room temperature is probed in the brazing processes of vacuum resistance stove and hi-frequency induction heating apparatus, respectively. Finally, the residual stress value of some special points of typical examples is achieved and compared with the experimental one of diamond residual stress by the means of Raman. The main creative contents in the paper are as follows: 1,Modeling of the brazed tools heated in vacuum resistance stove has been done and the results show that the obvious difference of linear expansion coefficient of the filler alloy applied and the steel substrate causes great thermal stress at the position close to the interface between the filler alloy and the tool substrate, which is the main reason of the fracture of the filler layer or the distortion of the tool substrate. The special filler alloy, of which the linear expansion is near that of the steel substrate, is advised. In spite of the obvious difference of linear expansion coefficient, the stress near the interface of the diamond grain and the filler alloy wouldn't cause diamond fracture when diamond has a global shape. But if the lamella diamond grain is chosen, it is more likely to be fractured. 2,Modeling of the brazed tools heated by hi-frequency induction has been conducted and the results indicate that the simulation results of the cooling process quite accord with the experimental ones. If the brazing process is controlled well, the stress field here is similar to that in the vacuum resistance stove. 3,The measuring experiment of the residual stress of the brazed diamond grains by Raman has been finished. And the results are consistent with the modeling ones well. The work accomplished in this paper could be favorable for the farther corresponding researches.