Research On Confocal Laser Measurement Method For Dimensional Measurement Of Workpiece Cavity

The measurement of the dimensions of the workpiece cavity has always been a difficult point for the production enterprise.Therefore,it is very important to carry out the research on the measurement method of the workpiece cavity size.Non-contact measurement technology is widely used in the measurement of workpiece dimensions,and the laser confocal measurement method has unique advantages due to its unique optical tomography capability and good measurement accuracy.In this paper,a confocal laser measurement method is studied for the measurement of the dimensions of the internal cavity components.The main work of the thesis is as follows:1.The principle of laser confocal measurement is introduced.On the basis of analyzing the measurement principle of dynamic active focusing method,the theory of single-light path confocal technology is further elaborated.At the same time,in order to better study the detection characteristics of the laser confocal technology,the optical path of the laser measurement system was simulated and designed in advance,and the correctness of the theory and the feasibility of the experiment were further explained in the following.The influence of the axial offset of the point detector and the size of the pinhole pupil on the confocal measurement system is theoretically analyzed.2.The structural scheme of the confocal measurement system was determined and the device was selected.Focus on the photoelectric information conversion and processing system has been deeply researched and discussed,designed photoelectric signal processing circuit,A/D acquisition circuit and single-chip control circuit,and through the microcontroller programming to achieve the detection of light intensity signal.3.The automatic focusing system is designed,and the focusing control method combining macro motion and micro motion is adopted to realize large-stroke,high-precision automatic focusing.The single-chip control circuit and the drive circuit of the two-stage feed Tab.are designed.At the same time,the mechanical structure design of the two-stage feed stage is carried out,so that the focus lens can perform focusing and fast and precise adj ustment.4.A confocal measurement system was built to make a corresponding experiment for the resolution of the photoelectric measurement system,the size detection of the confocal measurement system,the detection of the cavity size of the confocal measurement system,the repeatability of the confocal system,and the stability of the confocal system.And the experimental results were analyzed.The experimental research and exploration in the following paper also proves that the laser displacement measurement method based on the laser confocal principle has certain innovation and practical application value.The experimental results show that the confocal measurement system designed by this project has a resolution of 10 microns and good stability,and can measure the size of the inner cavity of the workpiece.