基于激光动态分束整形的高精度小模数齿轮曲面激光再制造研究

The technology of laser cladding is fit for remanufacturing of wron surfaces of high-accuracy small modulus gear due to its noble and versatile technical characteristics, such as, a small heat-affected zone and good metallurgical bonding. But in the condition of adopting the traditional laser beam, which energy is Gaussian distributed, stress state generated inner the gear tooth could not be matched with the stress generated by gear tooth engagement. The tooth surface should be overlapping clad due to the problem of collapsing at the edge of gear. And the risk of quality defects of clad layer, such as cracks and air holes, should be increased. Therefore，the working performance of remanufactured gear could not be recovered. With regrads to these problems, dynamic splitting and shaping of laser beam would be adopted to remanufacture the curved surfaces of gear. In connection with the parts with complex surfaces, internal stress states and deformation of parts generated by different input patterns of laser energy would be researched. And the laser energy mode fit for remanufactoring of the especial curved surface of gear could be designed. Various energy input pattern, such as multidomain distribution of laser energy in single laser beam, virious energy of multi-laser beam, would be researched in the project. And the masure of dynamic splitting and shaping of laser that fit for the curved tooth surface would be obtained. A reliable technique of remanufacturing of high-accuracy small modulus gear would be established at last. And the project could be referrence for the same research in remanufactoring of other parts with complicated surfaces and high demanding of internal stress state.

激光熔覆技术由于能使基体与表面覆层形成冶金结合及产生的热影响区较小等特点，适于高精度小模数齿轮齿面磨损后的再制造。但在采用传统高斯分布的单束激光条件下，轮齿内被诱导产生的应力状态，与齿轮啮合产生的应力状态是不匹配的。此外，齿顶、端面等边缘部位易出现的塌陷问题迫使需对齿面进行多道搭接熔覆，增加了裂纹、气孔等缺陷出现的几率，因此难以恢复再制造后齿轮的工作性能。针对该问题，本研究尝试采用激光动态分束整形的方法对齿轮进行再制造。探索渐开线齿面条件下，激光能量模式对齿轮内部应力场和变形的影响规律，据此设计适于齿轮曲面的激光能量模式。通过单束激光多区域能量分布、多束激光变能量并行输入等方法，实际获取相适应的激光能量动态分束整形方法，结合再制造齿轮质量控制研究，最终获得可靠且完善的激光再制造方案。研究结果对于探索表面复杂、对内部应力状态要求较高的零部件再制造方法具有指导意义。

激光熔覆技术由于能使基体与表面覆层形成冶金结合及产生的热影响区较小等特点，适于高精度小模数齿轮齿面磨损后的再制造。但在采用传统高斯分布的单束激光条件下，轮齿内被诱导产生的应力状态，与齿轮啮合产生的应力状态是不匹配的。此外，齿顶、端面等边缘部位易出现的塌陷问题迫使需对齿面进行多道搭接熔覆，增加了裂纹、气孔等缺陷出现的几率，因此难以恢复再制造后齿轮的工作性能。针对该问题，本研究尝试采用激光动态分束整形的方法对齿轮进行了再制造。分析了渐开线齿面条件下，激光能量模式对齿轮内部应力场和变形的影响规律，据此设计了适于齿轮曲面的激光能量模式。结果表明，多光束分布激光熔覆时，轮齿内部的温度分布更加均匀，而齿顶部位的最高温度明显下降，在保证齿面形成完整熔覆层的条件下，可避免齿顶的过度塌陷以及齿根部位的温度梯度过大。设计了三光束且能量分布不均匀的能量状态，可明显降低齿根部位的温度梯度水平，对降低齿轮熔覆后其内部的应力水平最为有利。搭建了相适应的试验平台，实现了多束激光变能量并行熔覆齿面，实际获取了相适应的激光能量动态分束整形方法，对再制造后的齿轮进行了运转实验，验证了再制造后齿轮运转的可靠性，最终获得了可靠且完善的激光再制造方案。研究结果对于探索表面复杂、对内部应力状态要求较高的零部件再制造方法具有指导意义。