Research On Bending Deformation Measurement Method Of Stepped Shaft And Screw Rod Parts Based On Laser Edge Detection

In the field of mechanical production and processing,shaft parts can realize many functions such as bearing load,positioning installation,and transmission of force and motion,so they are of great importance.Where the bending deformation is an important factor affecting the transmission accuracy and service life of the shaft parts.At present,the bending deformation measurement of conventional shaft parts(such as cylinder,and prism)has been mature.However,there are still technical defects or vacancies in the bending deformation measurement of complex shaft parts such as stepped shafts and screw rods.This paper proposes a new method for measuring the bending deformation of stepped shaft and screw rod parts based on the laser edge detection.The main contents are as follows:1.Research on measurement mechanism.Considering that the geometric shape of the measured parts has a characteristic of periodic cycle rotation,a continuous rotary measurement method based on laser edge detection was proposed.Combining the measurement principle and the geometric characteristics of the measured parts,a model for characterizing the reading of the laser edge detection sensor was established,and an algorithm for indirectly calculating the bending deformation of the measured part through the contour information of the inner and outer cylinders was proposed.A general contour representation model for stepped shafts and screw rods was derived through geometric methods,where the analysis of the screw rod used the guiding part of the electric hammer drill as an example.After simulation,the feasibility and accuracy of the entire measurement process were preliminarily verified.And the error analysis of the parameters that may affect the accuracy of the measurement results was performed,and the analysis conclusion was used as the guidance for the experiment.2.Construction of the measurement device.Based on the proposed measurement principles and models,a corresponding experimental device was constructed.First,the functions of the experimental device should be determined.Then,the main components and some connecting parts were selected or designed,and the transmission relationships for the device’s movements were analyzed.Finally,all components and circuits were installed strictly according to requirements to complete the construction of the device.To achieve feedback control of the device,displacement sensors and rotary encoders were mounted on the device to realize real-time monitoring and information transmission of its movements.In addition,a control program for the experimental device was developed using MATLAB,and a GUI operating interface was created to achieve automatic measurement through computer control.3.Experimental research on measurement.The developed device was used for experimental verification.Before the experiment,the laser edge detection sensor needs to be calibrated for pose.Then,the stepped shaft and screw rod were measured.Considering the existence of noise interference in the measurement data,the measurement data should be denoised.Finally,the denoised data was input into the target parameter solving algorithm to obtain the bending deformation results of the measured part.A comparative experiment was carried out using a contour projector to verify that the measurement method has good accuracy.Repetitive and reproducible analysis(GR&R)was conducted to verify that the method has good repeatability and reproducibility.The measurement method proposed in this paper not only avoids the inherent drawbacks of contact measurement,but also enables automatic,continuous and online measurement of bending deformation for stepped shafts and screw rods.Compared with existing point or line laser measurement methods,the laser edge detection method proposed in this paper mainly achieves measurement through projection,and the surface reflection of the measured part has almost no impact on measurement accuracy.In addition,laser edge detection does not need to consider the inherent characteristics of incident angles and spot shapes of point or line lasers,which makes it easier to adjust the pose of the laser edge detection sensor and simplify operations,greatly improving measurement efficiency.