Residual stresses in circular saw-blades tensioned by spherical multi-spot pressure

This paper analyzed the distribution of the centrifugal and thermal stresses of circular saw blades in working state, the residual stresses produced by roll and hammer tensioning, and the advantages and limitations of the two tensioning methods. In order to overcome the limitations and to save the advantages, a new tensioning method(multi-spot pressure tensioning)was developed. The residual stresses of the saw-blades caused by the multi-spot pressure tensioning were tested using X-rays. The results show that the tangential residual stresses outside the tensioning region caused by the new method enhance sharply with the increase of the saw-blade radius. It helped to eliminate the adverse effects brought by thermal stresses on the saw-blade stability, and improved saw-blade stability. This indicated that multi-spot pressure tensioning was a very effective method. Through X-rays test, it was found that the residual stresses in a tangential direction of the saw-blades were tensile stresses, whereas the stresses in a radial direction were compressive stresses both before and after tensioning. After the saw-blade was electrolysis-polished by 10 μm deep, the residual tensile stresses measured in tangential directions tended to decrease, but the residual compressive stresses measured in a radial direction tended to increase. It was also found that there were additional residual stresses regardless of the rim of the central bore, outer fringe and the areas near the slot or bore of the saw-blade because of the influence of machining.