针对“光束中空, 光内送粉”激光熔覆工艺方法, 通过改变激光功率、送粉速度、扫描速度、离焦量等工艺参数, 分别进行单熔道表面形貌、熔道宽度和高度的实验对比研究, 分析了环形光光内送粉的激光熔覆工艺参数对熔道成形质量的影响规律。结果表明, 激光功率较小将导致熔覆不均匀, 激光功率过大又会使熔道表面烧损, 随着功率的增加熔道宽度有增大趋势, 高度先增大后减小; 扫描速度过快会导致粉末不能充分熔化, 扫描速度过慢会增加熔道的厚度, 影响熔覆质量, 随着扫描速度的增加, 熔道宽度和高度均减小; 送粉速度增大导致熔化金属粉末增加, 但熔道宽度增加不明显, 当送粉速度过大时大量未熔化的金属粉末粘结在成形件的表面, 影响成形件质量; 随着离焦量的增加, 熔道宽度明显增加, 高度明显减小, 离焦量较小时熔道会烧损, 较大时熔道会无法形成。

According to a hollow-beam and laser-cladding-powder-feeding method of the laser cladding technique,comparative tests of the single-path surface topography and the melting width and height were studied respectively by changing parameters of laser power, feeding rate, scanning speed and defocusing amount so on. And the effect laws of process parameters on laser-path forming quality were analyzed. The results show that a lower laser power causes an uneven laser cladding, a high laser power damages the melting surface, the melting width increases and the melting height increases first and then decreases with the increasing of the power. If the scanning speed is too fast, the powder can’t be fully melted. If the scanning speed is too slow, the thickness of the melting path increases. These two factors affect the cladding quality. The width and height of cladding path decrease with the increasing of scanning speed. An increasing of feeding speed leads to an increasing of amount of melting powder, but the increase of the width is not obvious. And if the feeding speed is too fast, a lot of un-melted powder are bonded on the melting-forming surface to affect the quality of formed parts. With the increase of defocusing amount, melting width increases obviously and melting height significantly reduces. When the defocusing amount is small, the cladding path will be damaged. But when the defocusing amount is big, melting path will be unable to form.