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对激光直接制造金属零件过程中熔池温度和熔覆层厚度的变化进行了研究,指出对确定的材料,当激光功率增大到一定值时,熔池内的金属溶液大多已达到了热饱和,温度累积效应并不显著,熔池温度基本保持平稳,而在制造过程中若零件由于工艺不稳定而产生凹凸点,在多次层叠制造后,凹处越凹、凸处越凸,严重影响零件的制造精度。所以通过传感器来直接监测金属零件的熔覆高度,进而通过控制送粉量来保证制造过程中熔覆高度的稳定性比起温度控制来更具有实际意义。提出了熔覆高度的检测方案,并对送粉量的闭环控制系统进行了研究,对送粉量的时间延迟提出了相应的对策。结果表明对熔覆层高度的检测和对送粉量的调节能够提高激光直接制造过程的稳定性和制造精度。
The changes of the temperature of molten pool and the thickness of the cladding during the process of laser direct manufacturing metal parts are studied. It is pointed out that when the laser power is increased to a certain value, most of the molten metal in the molten pool has reached the thermal saturation, Temperature cumulative effect is not significant, the bath temperature remained stable, and in the manufacturing process if the parts due to process instability and bump points, after many laminated manufacturing, the concave concave, the convex convex, seriously affecting the parts Manufacturing accuracy. Therefore, by directly monitoring the metal cladding height by the sensor, and then by controlling the amount of powder to ensure the manufacturing process of the stability of the cladding height than the temperature control to have more practical significance. The test scheme of the cladding height was put forward. The closed-loop control system of the feeding amount of powder was studied, and the corresponding countermeasures were put forward for the time delay of the feeding amount. The results show that the detection of cladding height and the adjustment of the amount of powder feeding can improve the stability and manufacturing accuracy of laser direct manufacturing process.