Study And Real-time Control The Defocus Amount In The Laser Process Based On CCD And PMAC

The study is according to the accumulation of the open-loop control of the defocus amount for the current three-dimensional laser status quo, and self-developed a real-time closed-loop control system for the defocus amount, making the Z-axis single-layer AZ consistent with the forming pieces of single-layer stacking height Ah to ensure that each layer from focus the same amount, thereby overcoming the morphology of Rough up fine, On the fine under the rough and the edge of the jagged phenomenon.The paper analyzes the existing laser processing of a variety of closed-loop control research, introduces defocus amount of dynamic control in the laser forming process, and put forward the two sets of control programs based on the displacement sensor and CCD ranging.By contrast, this project adopted a "laser accumulation molding spacing dynamic monitoring tool" detection device based on the CCD, QCapture, C#development in the workbench PC, and the PMAC motion control card control software based on C++secondary development, to achieve real-time closed-loop control of the z-axis shift.The control programme is divided into three main parts:spacing collection, data transmission and reception, and the z-axis feedback control.The program takes full advantage of the CCD image capture function and C#, C++powerful programming capabilities and PMAC easy program-develoment for the integration of control with the core of IPC.Laser three-dimensional accumulation process is more than one parameter of the complexity of the role of physical metallurgical processes, using image processing Ranging Method to avoid the adverse effects of the powder splash, Ion cloud, smoke transpiration, and high temperature above the "bath" on the measurement.These advantages are also what it lacks in the existing displacement sensors.This program is to determine the numerical control system on the Z-axis on each shift by the crossmatch of measured value and set value. The results show that after the implementation of this program, the micro control of the light-mouth/optical port is within±0.25mm(storey change control is within±0.25mm). The accuracy of the accumulation forming parts is higher than those without using the real-time control of the defocus amount, and the inner and outer surfaces of forming pieces is smooth but no jagged, which effectively improves the stability of three-dimensional stacking process and the quality of the formed parts.