In the process of laser cladding or metal 3D printing, due to the dynamic changes in the shape, temperature, material and thermal conductivity of the substrate, as well as the fluctuation of the process parameters during the cladding process, it may lead to uneven heating of the cladding interface, and the instability of the molten pool with large fluctuations in its shape, size, temperature, and so on, which, under the combined effect of these problems, may result in the loss of control of the height and width of the stacked material, or even failure to form;

In addition, at the beginning of the two ends of the melting path, due to the existence of CNC motion machinery acceleration or deceleration process, may also lead to changes in the depth and width of the melt pool, so that the material forming out of control.

In order to reduce the instability factors in the process of laser cladding or metal 3D printing and improve the precision of metal forming, the main parameters of the laser cladding process can be closed-loop feedback control by means of optical and other monitoring means to achieve real-time monitoring of the size, shape and temperature of the molten pool and related data recording and analysis, and then real-time feedback adjustment or PID control of the process parameters, so as to achieve the effect of improving the stability of the process and the forming accuracy. The process parameters are then adjusted in real time or controlled by PID to improve process stability and forming accuracy.

Closed-loop feedback control hardware and software

The closed-loop feedback control system for Phono laser repair developed by Huirui. includes real-time monitoring and data feedback with invention patent (Patent No.: ZL 2013 1 0654910.7) and software copyright (Registration No.: 2016SR152148). It has a software interface that monitors the size of the molten pool and analyses the relevant data, and adjusts the width and shape of the molten pool through the corresponding parameter settings, in order to improve the stability of the laser cladding process and the forming accuracy.

Closed-loop software effectiveness

• Stable width of same-layer moulding;
•  Consistent wall width in the height direction;
• No over-thickness problem at both ends;
• Initial cladding width can be kept constant to ensure consistent thickness of single wall;