Development of Shotless Peening System and Manufacturing Considering Preservation of Environment

1.采用无充水腔的空化无喷丸强化系统，成功地实现了空气中的空化射流。结果表明，空气中的空化射流比水中的空化射流和空气中的普通水射流更强大。通过不同条件下的冲蚀试验和空化强度测试，对空化射流在空气中的作用能力进行了测试，得出了空化射流的最佳条件。用空化射流对几种钢进行喷丸处理，用x射线衍射法测量了残余应力。论证了残余压应力的引入。说明了利用空化射流进行表面改性的可能性。根据强化时间与残余应力或恒载荷下随强化时间变化的疲劳试验的关系，确定了最佳强化时间。5 .为了对比考虑环境防护的无喷丸强化与常规喷丸强化，进行了旋转弯曲疲劳试验，结果表明，无喷丸强化对疲劳强度的提高优于喷丸强化。为了建立评价无喷丸处理后表面改性层的无损检测方法，采用x射线衍射法测定了残余应力和奥氏体比。通过对齿轮齿的弯曲疲劳试验，对比喷丸强化的结果，证明了齿轮疲劳强度的提高。为了将无喷丸强化应用于各种材料，研究了空化强度与材料性能之间的关系，揭示了空化冲击的基本阈值水平。

1.The cavitating jet in air was successfully realized using cavitation shotless peening system without a water-filled chamber. It was revealed that the cavitating jet in air was most powerful compared with a cavitating jet in water and a normal water jet in air.2.The erosion test and measurement of cavitation intensity were carried out at various conditions to measure the ability of cavitating jet in air, then the optimum condition of the cavitating jet was obtained.3.Several steel were peened by the cavitating jet in air, the residual stress was measured by an X-ray diffraction method. The introduction of compressive residual stress was demonstrated. It shows the possibility of the surface modification by using the cavitating jet in air.4.The optimum peening time was obtained from the relation of the peening time and the residual stress or the fatigue test at constant load changing with the peening time.5.In order to compare the proposed shotless peening considering the prevention of environment and the conventional shot peening, a rotating bending fatigue test was carried out, and it was shown that the improvement of fatigue strength by shotless peening was better than that of shot peening.6.In order to establish non-destructive testing method to evaluate the surface modification layer peened by the shotless peening, the residual stress and austenitic ratio were measured by using an X-ray diffraction method.7.The improvement of fatigue strength of gear was demonstrated by a bending fatigue test of gear tooth comparing the result of shot peening.8.In order to apply the shotless peening to various materials, the relation between the cavitation intensity and the materials properties was investigated, and the fundamental threshold level of materials for the cavitation impact was revealed.