发动机曲轴高速电弧喷涂再制造工艺及热控制

High velocity arc spraying remanufacture process and thermal control for engine crankshaft

曲轴作为发动机的重要部件,采用高速电弧喷涂技术对磨损失效曲轴进行再制造可以实现"变废为宝"的目的。曲轴的主轴颈和连杆轴颈的轴心不在同一直线上,采用简单的喷涂路径不能一次完成整个曲轴再制造。基于机器人的高速电弧喷涂再制造曲轴过程采用不同的喷涂路径对涂层沉积过程中的散热有很大关系,热量在轴颈表面的不同分布状态影响涂层产生残余应力的大小和状态,从而影响涂层的使用寿命与再制造工件的服役可靠性。本研究根据曲轴形状特征,创新性设计了"环形"及"Z"字形喷涂路径,对两种路径下曲轴涂层的温度场进行了分析。结果表明:采用"Z"字形喷涂路径,计算调整曲轴转动时各轴颈表面的空间姿态和位置,模拟喷枪空间运动轨迹,可完成一次性曲轴自动化修复。通过机器人夹持喷枪实现复杂运动轨迹的再制造工艺过程,能够提高工艺过程的精确性,大大提高了生产效率,是"环形"路径的4倍。无论在曲轴"R"角位置还是轴颈处,采用"Z"字形路径制备涂层其表面温度比用"环形"方式喷涂低30~50℃,有效解决了以前曲轴喷涂再制造过程中"R"角位置涂层易产生过热而导致应力集中的难题,改善了涂层的性能。

The crankshaft is one of the important parts of the engine, using the high velocity arc spraying technology to remanufaeture the worn failure crankshaft can achieve the purpose of turning waste into treasure. The crankshaft axis of the main shaft and rod diameter is not in the same line, so Ihat the simple spraying path cannot be used to complete the crankshaft remanufacturing. Robotic high velocity arc spraying technology thai applied to remanulacture the crankshaft was related to heat distributed on the erankshaft surtace while using different spraying paflls. Then lhe heat distribution will aft^ct the service life and reliability of the remanuihctured crankshM＇t. In this study, according to the shape characteristic and surthce position of the crankshaft, the ＂ring＂ and ＂Z＂ zigzag spraying paths were innovatively designed, and the temperature fieht of the crankshaft coating on the two paths was analyzed. The results show that it can complete the automatic repair of the crankshaft when the ＂Z＂ shaped spraying coating deposition path is used to calculate and adjust both the space posture and posilion of each journal surface of the crankshaft during the erankshal＇t rotates, and simalate the space movement trajectory, of the spray＇ gun. The remamdhcturing process of the complex motion track through robot clamping spray gun can improve the accuracy of the process,and greatly improve the production efficiency, which is four times the ＂ring＂ path. Whether in the crankshaft ＂R＂ corner or the shaft neck, the coating surface temperature using ＂Z＂ zigzag spraying path is lower 30-50 ℃ than that using the ＂ ring＂ path. It effectively solves the challenge of eoating overheating and stress concentration in the ＂R＂ corner in the crankshaft remanufacturing process, and improves the coating performance.