20CrMnTi渗碳淬火齿轮表面残余应力的超声法检测

发布时间：2018-03-30 02:04

本文选题：齿轮　切入点：表面残余应力　出处：《南昌航空大学》2016年硕士论文

【摘要】：齿轮作为受到交变疲劳载荷的零件,其表面质量非常重要,表面残余应力分布对疲劳强度有重大影响,不利的应力分布将促使齿轮疲劳失效的发生。本文以20CrMnTi渗碳淬火齿轮为研究对象,在超声波应力检测方法理论研究基础上,尝试利用临界折射纵波(Critically Refracted Longitudinal,LCR Wave)方法研究齿轮表面残余应力的分布规律,为齿轮等结构特殊的传动构件的表面质量检测提供依据。本文设计了LCR波探头,并通过CIVA参数仿真与具体实验相结合的方法验证设计方案的准确性与可靠性。系统地研究了LCR波形特征、衰减与渗透深度规律,以及入射角度对LCR波的影响。设计并搭建了齿轮表面残余应力检测系统,包络齿轮表面应力检测用探头,硬件系统设计和软件系统开发;制定了超声应力系数标定实验方案并获得了齿轮应力系数。对20CrMnTi渗碳淬火齿轮表面残余应力分布进行分区域检测,并对影响因素进行分析;采取X射线衍射法在定性上对超声法检测齿轮表面残余应力结果的合理性进行验证。研究表明,本文设计的LCR波探头具有较好的准确性与可靠性,仿真与验证实验均与理论情况相符。LCR波传播时间的变化与传播方向上的应力变化近似呈线性关系。被测齿轮整体轮齿表面残余应力主要为压应力,与渗碳淬火齿轮表面残余应力的理论分布情况一致,符合齿轮制备的一般要求。局部应力集中造成残余应力值较大,渗碳层较薄与轻度磨损导致表面残余拉应力的存在;被测齿轮根部表面进行了淬火硬化处理,提高了齿轮的抗弯曲疲劳性能。耦合条件与温度等外部因素对检测结果均有一定的影响。在定性上,X射线衍射法实现了对超声法检测齿轮表面残余应力合理性的验证。本文设计的齿轮应力检测方法与理论具有较好的可行性,研究结果对无损、高效地齿轮表面质量检测提供参考。
[Abstract]:As a part of gear subjected to alternating fatigue load, the surface quality of gear is very important. The distribution of surface residual stress has a great influence on the fatigue strength, and the unfavorable stress distribution will promote the occurrence of gear fatigue failure.Taking 20CrMnTi Carburizing and quenching gear as the research object, on the basis of the theory of ultrasonic stress measurement, this paper attempts to study the distribution of residual stress on the surface of gear by using critical refraction longitudinal wave (critical Refracted longitudinal wave) method.It provides the basis for the inspection of surface quality of transmission components with special structure such as gears.In this paper, the LCR wave probe is designed, and the accuracy and reliability of the design scheme are verified by combining the CIVA parameter simulation with the concrete experiment.The characteristics of LCR wave, the law of attenuation and penetration depth, and the influence of incident angle on LCR wave are systematically studied.The paper designs and builds a gear surface residual stress detection system, a probe for envelope gear surface stress detection, hardware system design and software system development, and formulates an experimental scheme for ultrasonic stress coefficient calibration and obtains gear stress coefficient.The distribution of residual stress on the surface of 20CrMnTi Carburizing and quenching gear was detected in different regions and the influencing factors were analyzed. The rationality of ultrasonic method in measuring residual stress on gear surface was verified qualitatively by X-ray diffraction method.The results show that the LCR wave probe designed in this paper has good accuracy and reliability, and the simulation and verification experiments are in accordance with the theoretical situation. The variation of propagation time of the LCR wave is approximately linear with the stress change in the propagation direction.The residual stress on the surface of the whole gear is mainly compressive stress, which is consistent with the theoretical distribution of residual stress on the surface of carburized and quenched gear, and meets the general requirements of gear preparation.Local stress concentration results in large residual stress, thin Carburizing layer and mild wear lead to the existence of residual tensile stress on the surface. The surface of the measured gear root is hardened and hardened to improve the bending fatigue resistance of the gear.External factors, such as coupling conditions and temperature, have a certain effect on the detection results.Qualitatively, X-ray diffraction method is used to verify the rationality of ultrasonic method in detecting residual stress on gear surface.The method and theory of gear stress detection designed in this paper are feasible, and the research results provide reference for nondestructive and efficient gear surface quality detection.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG162.73;TG115.285

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