Residual stresses in circular saw-blades tensioned by spherical multi-spot pressure
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摘要: 该文综合分析了圆锯片在工作中受到的离心应力、切削热应力以及辊压和锤击适张产生的适张残余应力，并比较了辊压和锤击两种适张方法的优点和不足.为了取长补短，作者提出了多点加压适张新方法，即用球面、柱面或锥面等压头对锯片进行加压适张.研究中用X射线应力检测仪对球面多点加压适张后锯片内的残余应力进行了测定.结果表明，新适张方法所获得的应力分布曲线相当理想，即适张获得的残余应力几乎抵消了锯片在工作中受到的离心应力和热应力之和.这表明多点加压是一种很有开发价值的圆锯片适张新方法.此外，X射线检测时，在适张前后，锯片切线方向皆为拉应力，而径向为压应力.经电解抛光10μm后，无论径向还是切向，所测得应力的绝对值都有不同程度的下降.由于机加工的影响，锯片中心孔边缘、锯片外缘和槽孔附近存留一定的残余应力。Abstract: 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.
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Keywords:
- circular saw-blade /
- multi-spot pressure tensioning /
- X-rays /
- residual stress /
- electrolysis-polish
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