激光点焊工艺参数对止推箔片轴承接头组织与性能的影响

止推箔片轴承是航空陀螺仪中的重要支撑元件,为了提高支承面的耐磨性及耐腐蚀性,通常会在支承面涂覆特氟龙涂层,该涂层的添加给后续的制造工艺带来不确定性。研究激光点焊工艺参数对止推箔片轴承接头组织与性能的影响,利用光学显微镜、扫描电镜、电子精密拉伸仪、超声检测等分析方法,对焊缝表面成形、接头显微组织及力学性能进行分析。结果表明:焊点表面直径随脉冲功率的增加而增大,而抗拉剪力随热输入量的增加先增大后减小;激光点焊制造的优化工艺参数为脉冲功率百分比22%、脉冲宽度5.0ms,抗拉剪力达最大值63.0N;超声波浸液检测能够精确测定搭接界面的尺寸,但抗拉剪力与界面尺寸不完全成正比关系,接头的抗拉剪力主要与接头的断裂机制有关。

Effects of Process Parameters on Microstructure and Performance of Joints for Laser Spot Welding of Thrust Foil Bearings

The thrust foil bearing is an important support element in the aviation gyroscope.In order to improve the wear resistance and corrosion resistance of the supporting surface,Teflon coating is usually coated on the supporting surface,while the addition of this coating brings uncertainty to the subsequent manufacturing process.In this paper,the effects of laser spot welding process parameters on the microstructure and performance of thrust foil bearing joints were studied.The analysis methods such as optical microscope,scanning electron microscope,electronic precision tensile tester and ultrasonic testing were used to analyze the weld surface forming,joint microstructure and mechanical properties.The results showed that the surface diameter of joint increased with the increase of pulse power,while the tensile shear force increased first and then decreased with the increase of heat input.The optimized process parameters of laser spot welding manufacture:pulse power percentage 22%,pulse width 5.0 ms,tensile shear force 63.0 N;Ultrasonic immersion testing can accurately measure the size of the lap interface,but the tensile shear force was not fully proportional to the size of the interface.The tensile shear force of the joint was mainly related to the fracture modes of the joint.