On-Line Measurement Technique Of Hot Bar Section Profile And Diameter

A measurement scheme based on the principle of laser 3D vision measurement is developed in this paper for the measurement of hot bar. And related research has been done on key technology. Suitable cameras and lasers are purchased according to the site environment and the accuracy requirements of the project. The system has been built in the lab. The calibration of the system is completed by using a newly designed 3D target based on the Zhang camera model. The 3D target has four target surface corresponding four sets of sensors. The system can accomplish the calibration of the four sensors at the same time and unify measurement coordinate system by using geometrical relationship of the target surface. The calibration method is simple and easy to operate, which is very suitable for field application.This paper puts forward a method to process the 3D data of the section profile which is measured separately in four parts. To get more ideal three-dimensional coordinate, the system introduced a processing method by using the thought of average and least squares fitting arc. The measurement of the diameter is accomplished by using eight groups of parallel lines. Eight groups of parallels lines approach the section circle from two opposite directions. Tangent points can be achieved from the above steps, but the points should be judged and screened to make the right decision.Then we can get the right diameter in eight different positions.Calibration experiments and measurements are carried out in the laboratory. The intrinsic and external camera parameters and light parameters can be got from the calibration experiment. Accuracy verification experiment is made by measuring cone pulley. The measuring results showed that the system can obtain the real-time hot bar section profile and diameters in different positions in a certain range. Measuring accuracy is within 0.2mm, and the system is stable while measuring.