Research On Straightness Measurement Method Of Large Aspect Ratio Circular Pipe Axis

As an important part of weapon equipment,the barrel will be bent and deformed due to special conditions such as processing technology,transportation,inevitable collision in process,too large self weight and long time placement of the barrel.The bending deformation seriously affects the firing accuracy of the gun tube and affects the trajectory of the shell in the hole,The excessive wear on the inner wall of the gun tube will greatly reduce the service life of the gun pipe.Based on the above problems,this paper studies the straightness of the axis of the large diameter ratio circular pipe with the diameter of 30 mm in the inner hole of 2.7m.The purpose of this paper is to provide a testing method for the straightness measurement of pipe fittings based on LabVIEW software platform,and provide a basis for the subsequent straightening work of the cannon pipe.The thesis studies from the following aspects:(1)Mechanical platform for straightness measurement of large aspect ratio pipe.Considering that the positioning of the pipe is the direct factor that affects the accuracy of the straightness measurement in the process of the straightness measurement of the pipe,combined with the field working environment and the technological requirements required in the measurement process,the fixture design of the laser transmitter and the pipe to be measured is carried out.A tube clamp and a three degree of freedom laser trimming platform are constructed to ensure that the tube will not roll and the two end faces of the tube can be quickly zeroed.At the same time,the positioning structure of the laser receiving unit and the measurement data transmission unit are further designed to meet the data transmission of the actual tube straightness measurement and improve the measurement accuracy.(2)Hardware of straightness test instrument for large aspect ratio tube.Considering the large beam energy and strong directivity of the laser transmitter,the "optical axis method" is selected to measure the straightness of the inner hole axis for the purpose of accurate measurement of the straightness of the circular tube.Design and determine the laser transmitter,PSD(post sensing detectors)target,push rod,reading display,push rod with scale,cable,small hole support leg,form a set of instrument hardware structure suitable for the straightness test of circular tube,which provides hardware support for the accurate straightness measurement of circular tube.(3)Software of straightness measuring instrument for large length diameter ratio tube axis.This paper analyzes that when the PSD measurement data is transmitted to the reading display through the cable,the reading display can be remotely transmitted to the PC,and puts forward the method of programming software module based on LabVIEW software programming language.The software module mainly includes data acquisition and measurement module,data processing module,data display module and data storage module.At the same time,according to the software module,the deflection angle of the measurement point about the reference axis is further studied,and the real-time processing of the measurement data is realized.Finally,combined with the advantages and disadvantages of various file formats,the appropriate file format is selected to save the measurement data,and the functions of human-computer interaction,measurement,data processing and data saving of the measurement software are realized.(4)Field test of straightness of large length diameter ratio circular pipe axis.Combined with the hardware system of the selected measuring device and the debugged software processing system,the on-site experimental verification of the pipe to be measured was carried out,the reference axis of the on-site straightness measurement of the round pipe was determined,and the actual radial deviation and deflection angle data in different measuring planes were obtained,Finally,based on LabVIEW software platform,the pipe straightness measurement method is provided to realize the measurement of pipe straightness.