Study On Laser Non-contact Thickness Measurement Method Based On CCD

Steel manufacture is one of the pillar industries improving the development of nationaleconomy. Now the competition of the world iron and steel enterprises is fierce and the focusis to get high quality product using low cost. With the development of the economy andtechnology, the need of iron is growing. Meanwhile the request of the steel product isincreasing, such as whether the rate of thickness is on average, the size and breadth meet thestandard and so on. All the above questions restrain the development of the steel products andthe economy benefits of enterprises. Among them the steel thickness is an important qualityindex which influences the next operation of the products.The thickness measurement before is artificial and tangent. Workers use vernier caliperand large-scale calipers to measure the steel thickness dynamically. These methods requiregreat intensively labor and it has low measurement accuracy. Meanwhile it’s easy to damagethe surface of products and the measurement speed is slow, so it has a great deal influence onthe production efficiency. There are also other methods like mechanical measurement orradioactive measurement but they are not ideal and abandoned. They have either lowmeasurement accuracy or are harmful to the environment and people. So people put theresearching focus on the optical technology and expect to get the new non-contactmeasurement method using optical principles.With the rapid development of optics and laser technology, a non-contact steel thicknessmeasurement method is put forward which is using laser technology. After studying manydetective methods at home and abroad, a method of double laser non-contact thicknessmeasurement suggested in this paper which is based on linear CCD is to solve questionsmentioned above. It uses laser light, CCD and computer control technology which improvesthe measurement speed and accuracy and has some practical value for the cold-roll steelsheets.The double laser non-contact thickness measurement method is based on principle oftriangle slanting. It has no detecting limits about materials. The mathematic model is built bythe relation of light intensity and facular displacement on the CCD. The critical componentsfor the system are selected according to the detecting range and requirements of cold-roll steelsheets. The driving circuit of linear CCD is designed by programmable logic device and imitated using Quartus II software. The feasibility of the driving circuit is verified.Meanwhile the facular displacement is compensated through calibration in order to decreasethe interference from the outer environment. At last the experiment of the detecting method isoperated and the imitating software is designed to verify the method. Through the experimentand simulation the feasibility and reliability is demonstrated.