Research On Ultrasonic Non-contact Conformal Scanning Thickness Measurement Method

Accurate measurement of wall thickness is an important link in the manufacturing process of large thin-walled parts.Among many wall thickness measurement methods,ultrasonic thickness measurement is widely used because of its advantages in industrial field measurement,especially the ultrasonic on-machine non-contact scanning thickness measurement method has the characteristics of high efficiency,high precision,and high degree of automation.However,the deformation of large thin-walled parts after clamping is relatively large,and it is difficult to maintain a stable measurement state when ultrasonic scanning thickness measurement is carried out on the preset path,so that the accuracy of thickness measurement and the safety of the thickness measurement process cannot be guaranteed.Therefore,how to plan the ultrasonic scanning thickness measurement path is a key issue in the ultrasonic scanning thickness measurement of large thin-walled parts.The ultrasonic signal measured on the machine is transmitted to the industrial computer for thickness calculation through wireless transmission,which can reduce the changes to the existing circuit of the machine tool,and conveniently realize the automatic switch between the wall thickness measurement process and the machining process.However,the amount of ultrasonic signal data is large,and the surrounding environment of the machine tool is complicated and interferes seriously,resulting in low signal-to-noise ratio of the ultrasonic signal.Therefore,how to achieve stable transmission of ultrasonic signals and high-efficiency denoising is a key issue in the wireless transmission of ultrasonic signals.Aiming at the problems of how to determine the adjustment value for scanning measurement path planning,generating adjustment paths and scanning obstacle avoidance,based on the idea of path-probing measurement,an integrated ultrasonic thickness measurement device is designed,that is,a displacement sensor is installed in front of the ultrasonic sensor movement.Guide the dynamic correction and adjustment of the scanning measurement path.By determining the adjustment value of the Epanechnikov kernel density estimation,the number of adjustments can be effectively reduced.Next,in order to achieve continuous and stable control,the method of adjusting the path generation method based on the energy method is studied,at the same time,the noise in the scanning thickness measurement process is based on the robot obstacle avoidance idea.Constructed a scanning obstacle avoidance process based on grid method environment modeling and ant colony algorithm.Aiming at the problems of large data volume and low signal-to-noise ratio in the wireless transmission of ultrasonic signals,an ultrasonic thickness measurement device based on wireless communication is designed,which can realize the automatic switching of processing and measurement;the ultrasonic signal lossless compression method based on LZW algorithm and The ultrasonic signal transmission method based on wireless bandwidth effectively improves the transmission efficiency.The wavelet threshold method based on the adjustable quality factor denoises the ultrasonic echo signal and optimizes its parameters to achieve a good denoising effect.Based on the Siemens 840d sl open CNC platform and large grid wall thickness measurement requirements,the non-contact conformal scanning thickness measurement algorithm is programmed to form a large-scale thin-walled ultrasonic automatic thickness measurement system,rapid ultrasonic signal processing experiments are carried out.To verify the effectiveness of the proposed ultrasonic signal rapid processing method,ased on the GMC2650 CNC platform and ultrasonic automatic thickness measurement system,comprehensive experiments were carried out to verify the effectiveness of the proposed conformal scanning thickness measurement algorithm and its positive influence on the ultrasonic thickness measurement process.