【作者】 张超；

【导师】 姜兴宇；

【作者基本信息】 沈阳工业大学 ， 机械工程， 2021， 硕士

【摘要】 激光熔覆技术是利用高能量高密度激光束射入金属基体形成熔池,实现金属基体与熔覆材料之间结合,形成具有耐磨、耐高温、抗腐蚀等特性的熔覆层的一种高新技术。熔池温度是影响熔覆层成形质量的主要因素,熔池温度的变化会导致熔覆层形貌与性能不稳定,如何有效控制熔池温度是激光熔覆控形控性的关键。因此,研究激光熔覆熔池温度的控制系统,保证熔池温度稳定对于提高激光熔覆成形件形貌与性能稳定性具有重要工程意义。基于此,本文以VMC850E与IPG激光器自主集成的激光熔覆成形系统为实验平台,深入分析在激光熔覆过程中工艺参数对熔池温度的影响规律,开发基于增量型积分分离PID的熔池温度闭环控制系统,主要研究内容如下:(1)针对影响激光熔覆层形貌与熔池温度因素多、影响关系复杂问题,探究工艺参数对熔覆层形貌与熔池温度影响规律,通过单因素与正交实验,揭示激光功率、扫描速度、送粉速率等工艺参数对熔池温度的影响规律,为后续激光熔覆熔池温度控制系统开发奠定基础。(2)针对激光熔覆过程熔池温度不稳定导致成形质量差问题,搭建激光熔覆熔池温度监控平台,提出一种基于增量型积分分离PID的熔池温度闭环控制方法,并应用Visual Studio C++,开发熔池温度闭环控制系统,实现激光熔覆过程熔池温度的实时调控。(3)为验证激光熔覆熔池温度控制系统有效性与可靠性,设计开环与闭环控制激光熔覆实验,分析激光熔覆过程中熔池温度梯度变化,并针对薄壁墙实验试件的尺寸精度、显微组织及硬度进行对比,进一步验证熔池温度控制系统的有效性。更多还原

【Abstract】 Laser cladding technology is a high-tech technology that uses high-energy and high-density laser beams to inject into the metal matrix to form a molten pool,realizing the combination of metal matrix and cladding materials,and forming a cladding layer with wear resistance,high temperature resistance and corrosion resistance.The molten pool temperature is the main factor that affecting the forming quality of the cladding layer.And the change of the molten pool temperature will lead to the instability of the morphology and performance of the cladding layer.Moreover,the effectively control of the molten pool temperature is crucial to the shape control of laser cladding.Therefore,it is of great engineering significance to study the control system of laser cladding molten pool temperature and ensure the stability of molten pool temperature for improving the morphology and performance stability of laser cladding forming parts.This work takes the laser cladding forming system independently integrated by VMC850 E and IPG laser as the experimental platform.Then,a deeply analyze on the relationship between the process parameters and the molten pool temperature in the laser cladding process is conducted.Finally,the closed-loop control system of molten pool temperature based on incremental integral separation PID is developed.The specific research contents are as below:(1)To cope with the problem that a large number of affecting factors and complex influence relationship of the laser cladding layer morphology and the molten pool temperature.The single factor and orthogonal experiments is conducted to explore the influence law of process parameters such as laser power,scanning speed and powder feeding rate on the temperature of molten pool,which lays a foundation for the development of subsequent laser cladding molten pool temperature control system.(2)To solve the problem of poor forming quality caused by unstable molten pool temperature in laser cladding process,a molten pool temperature monitoring platform is constructed,and a closed-loop control method of molten pool temperature based on incremental integral separation PID is performed.The closed-loop control system of molten pool temperature is developed by Visual Studio C + +,in this way,the real-time control of molten pool temperature in laser cladding process is realized.(3)To verify the effectiveness and reliability of the molten pool temperature control system of laser cladding,the open-loop and closed-loop laser cladding experiments are designed to analyze the temperature gradient change of molten pool in the laser cladding process.The comparison experiments of thin-walled wall specimens in dimensional accuracy,microstructure and hardness are conducted.As a result,the effectiveness of the molten pool temperature control system is further verified.更多还原