Measurement System For Ladle's Wall Thickness Based On Laser Positioning And Scanning

In the steel metallurgical industry field,ladle is a transition container and intermediate smelting equipment during the process of continuous casting production.It's inner wall thickness is an important information during the process of continuous casting.The accurate measurement of wall thickness of ladle has direct effect on controlling temperature of molten steel,preventing leakage steel,improving quality of casting and saving costs of continuous casting production and so on.Accurately grasping the lining erosion state of ladle and repairing the lining of ladle in time,which can prolong the service life of ladle.Therefore,it is of practical significance to measure the wall thickness of ladle accurately.Ladle is filled with molten steel during the continuous casting production,which lead to the inner wall of ladle always in a high temperature state.At the same time,the ladle is lifted by crane,which lead to difficulty of determining the placement of ladle.The ladle in multiple-dust and strong interference also cause difficulty to the wall thickness measurement of ladle.So some methods,such as capacitance,resistance,thermocouple,ultrasonic and model deduction calculation and so on,can not measure the wall thickness of ladle accurately.At present,it mainly based on manual experience to estimate the wall thickness of ladle in metallurgical industry field,which is difficult to ensure measurement accuracy with strong guesstimate.Because it is difficult to accurately measure the wall thickness of ladle,this paper designs a system to measure the wall thickness of ladle based on laser positioning and scanning.The main research contents are as follows:1.Solution to wall thickness of ladle based on laser positioning and scanning.This article puts forward a method to measure wall thickness of continuous casting ladle based on laser positioning and scanning.Firstly,positioning lasers are used to detect the spatial coordinates of the measured ladle.Secondly,the inner surface of the ladle is scanned by measuring laser driven by a rotary platform.According to the spatial coordinate transformation,the data of the measured points on the inner surface of the ladle are mapped to the wall thickness of the ladle.Finally,the thickness distribution of the inner wall of the ladle is obtained by comparing wall thickness with the standard initial data of the ladle.2.Three-dimensional reconstruction of laser positioning and ranging.Because of the unknown place between laser ranging sensor and the measured ladle,positioning lasers are used to detect the spatial location of the measured ladle.Then,scanning platform scan the inner surface of ladle to collect distance data between measured point and measuring laser.According to the spatial coordinate transformation,ranging data are mapped to ladle coordinate system by means of coordinate transformation to calculate the wall thickness of ladle.Finally,turn the discrete wall thickness data into intuitive wall thickness curve by interpolation and fitting.The thickness distribution of the inner wall of ladle is obtained by comparing with the wall thickness of the standard initial data of ladle.3.Step control of scanning platform based on fuzzy PID.The scanning platform is two degrees of freedom,which can drive measuring laser scanning the inner surface of ladle horizontally and vertically.In order to solve the problem that stepping motor is unstable run and low control accuracy in open-loop control.The photoelectric encoder is feedback the position of stepping motor,and the fuzzy PID control algorithm is applied to improve control precision of scanning platform.The measurement system for ladle's wall thickness was verified by experimental test and field application.New ladle and online used ladle were measured,and the laser measurement results was compared with the manual measurement.According to the experimental results,the maximum measuring error is 5.2 mm,the minimal error is 2.6 mm,and the average error comes to 3.6 mm.The results from theoretical analysis and field application show that the measurement system in this paper can accurately and reliably measure the wall thickness of ladle,which meet production needs.The measurement principle can also be extended to other similar smelting container measurement occasions.So the measurement system for ladle's wall thickness based on laser positioning and scanning has wide application prospect.