Study On Long Guide Rail Straightness Measurement System Based On Position-Sensitive Detector(PSD)

Straightness is a form tolerance which limits the variation of the actual straight line relative to the ideal straight line.Straightness error is the most important measure index of the guide rail's quality,which directly determines the working performance of the guide rail.Traditional straightness error measurement methods such as ruler and steel wire are simple,but have the disadvantage of low efficiency and low precision.Although the new type of the measuring instruments have the advantage of high precision,its price is too expensive to meet the actual needs.In view of this,this paper takes the long guide rail's straightness error as the research object,taking into account the precision and the economic requirement,and proposed the new measurement method which take the laser as the reference line and the two-dimensional spot position sensor as the photoelectric sensor.In this thesis,the overall detection scheme is designed for the measurement requirements:We have theoretically analyzed the measurement principles and verified the feasibility of the scheme.The long guide rail straightness measurement system takes the two-dimensional spot position sensor as the core,the beam emitted by the He-Ne laser as the reference line.We designed the Bluetooth module for remote data transmission and used the Python writing the straightness error calculation program based on the least squares method.We verified the accuracy of the two-dimensional spot position sensor by a high-precision displacement platform control experiment,reaching 3.4?m.We designed experimental experiments and tested the 7.2m long rail at the factory,the results showed a repeatability up to 5?m.At last,We analyzed the various factors that may cause systematic measurement error through theoretical modeling and experiments.As a result,a new method is provided for long guide rail's straightness error measurement,which is simple and efficient.