建立了侧向送粉激光熔覆粉末颗粒温升的数学模型,该模型可以考虑激光束的功率分布。推导了考虑激光束直径大于粉斑直径和小于粉斑直径两种情况下,粉末颗粒在光束辐照下的温升与其在光束下运动时间的关系式。通过算例,给出了在不同激光功率下粉末颗粒的温升随其与激光束相互作用时间的关系曲线以及不同颗粒直径条件下粉末颗粒温度随相互作用时间的关系曲线。采用微距摄影技术对粉末颗粒到达熔池表面的状态进行实验观测,并采用图像分割技术中的迭代阈值选取方法,对所获得的灰度图进行处理从而得到了粉末颗粒到达熔池的温度。计算结果与实验分析获得了相同的结论,从而验证了模型的正确性。

A temperature rise model of laser cladding material powder by side-injection is established. In this model, the distribution of laser power is considered. The relation formula between the temperature rise of the powders and the time that the particles moves under the laser beam shine is deduced by considering two kinds of circumstances when the diameter of laser beam is larger or smaller than the diameter of powder spot. The paper presents the relationship between the temperature rise and moving time of the powders for different laser power. The paper also presents the relation between the temperature rise and the interaction time for different powder diameters. The micro-distance photograph technique and the image segmentation technique are used to investigate the state and temperature of the cladding material particles after its passing through the laser beam. The experiment analysis validates the model prediction.