基于多工艺复合的超硬磨料砂轮修整技术与机理研究

Along with the increase of hard-brittle materials such as engineering ceramics, optic glass and single crystal silicon applying in engineering fields in recent decades, diamond grinding wheels have been employed more and more frequently to obtain the high dimension and form accuracy. The trimming skill which uses laser auxiliary heating and two-dimensional ultrasonic vibration mechanical was put forward,by combination the mechanical trimming method and theory of special processing. According to study the dynamic behavior of the two-dimensional ultrasonic complex acoustic system, the impedance matching model and the system model of vibration stability was established;the key skill of design of two-dimensional vibration mode ultrasound acoustic system was gained,the trimming device of the complex laser and ultrasound was set up.At the condition of that the typical thick super abrasive wheel was an object and the optimal temperature which was gotten by laser auxiliary heating was premise,the experiment of process parameters optimization was done so as to smart the mechanism of materials removal and the process regulaiton,establish the thermal dynamic coupling model of the compsite of laser and trimming study the influnce regulation of process parameters to the profile of wheel and the microscopic status of grains.Based on this research, the online system of monitoring and trimming, was studied in order to trim the wheel automatically and intelligently. According to this study, a new trimming technique could be provided so that the surface morphology quality of super abrasive wheel and the high-efficient precise process of the difficult-to-cut materials could be improved.

超硬磨料砂轮的修整技术是实现难加工材料精密、超精密加工的关键技术，超硬磨料砂轮（尤其是复杂型面砂轮）修整效率低、精度难控至今仍是制约它发展的瓶颈性难题，本研究主要为破解这一难题而提出基于激光热效应的二维超声振动机械复合在线修整技术。以提高砂轮修整质量、修整效率为目标，通过研究二维超声复杂声学系统的动态特性，建立其阻抗匹配模式和系统振动稳定性模型，突破二维振动模式超声声学系统设计的关键技术，以典型的密实型超硬磨料砂轮为修整对象，以实现激光辅助加热温度最优控制为前提，进行工艺参数优化试验，研究激光超声复合修整的材料去除机理和工艺规律，建立激光超声复合修整过程中材料去除热力动态耦合模型，揭示工艺参数对砂轮廓形及磨粒微观状态形成的影响规律，在此基础上架构在线监测与修整系统，实现修整过程的自动化、智能化；为提高超硬磨料砂轮修整质量，进而提高难加工材料高效精密加工效率及加工精度奠定理论与技术基础。

本项目针对超硬磨料砂轮修整效率低、精度难控及修整工具磨损严重的技术难题，将传统修整技术与特种加工理论相结合，提出一种采用二维超声和激光加热辅助进行超硬磨料砂轮精密修整的方法，并对砂轮修整过程中的关键技术问题进行研究。提出了一种新型的二维超声椭圆振动修整装置，在波动理论的基础上，结合质点的振动原理，研究了变幅杆中波的传播特性，并根据机械阻抗综合法对振动装置进行阻抗的匹配分析。在理论分析的基础上，完成了振动装置各个部件的几何尺寸设计，并对声学装置的振幅和频率特性进行试验分析。然后通过有限元对激光加热辅助修整过程进行了仿真，探索了激光工艺参数对修整效果的影响规律，仿真结果为超硬磨料砂轮精密修整的参数选择提供了有力的依据。基于高速影像采集技术，搭建了在线监测系统，通过超声、激光、在线监测整合，架构了实验平台。.开展超硬磨料砂轮的激光超声复合精密修整实验，探讨了修整深度、修整进给量、主轴转速、超声功率、激光加热功率等工艺参数对砂轮廓形及磨粒微观状态的影响。基于三维白光干涉扫描技术，提出了砂轮表面的磨粒识别方法，建立了三维表面形貌特征描述的评价模型。在此基础上，开展了超声振动激光加热辅助金刚石修整器修整的材料去除机理研究，在激光辅助超声振动修整中，一方面，当激光加热砂轮表面时，随着温度提高使得砂轮表面材料软化，材料切除过程变脆性断裂为塑性流动。另一方面，二维椭圆超声振动修整过程中，超声波进入冷却液后形成声空化效应，使液体微粒形成空化气泡，空化气泡闭合产生的巨大压力反复冲击砂轮表面，在清洗砂轮的同时，也加速了结合剂和磨粒的破碎与断裂。在激光加热和高频超声振动冲击下，使得修整过程中，修整力减小，结合剂材料容易去除，在修整器刀头轨迹轮廓底部及与砂轮接触区顶部磨粒存在许多微破碎，形成磨削微刃。有限元仿真和实验结果表明当各工艺参数选择合适时，激光超声复合辅助修整可以很大程度地降低修整力，使修整过程更加稳定，且可以使砂轮表面形貌得到很大改善，更适合于精密超精密加工，是实现超硬磨料砂轮修整的有效方法之一。研究期间发表论文9篇，申请国家专利5项，授权2项，培养硕士研究生4名，参加国内外学术会议15人次。