Research On Automatic Positioning And Realization Of Nondestructive Testing Equipment For Residual Stress

Non-destructive testing of residual stress is to detect the magnitude of residual stress through radiation,magnetism,sound,etc.,which have different physical effects when passing through materials in different states.It can provide an important basis for the development of basic materials,key parts detection,design,and processing technology.Traditional residual stress testing is mainly destructive testing.By mechanically removing part of the sample material,some or all of the residual stress in the sample is released,and then the deformation of these parts is measured,and the original residual stress is calculated by mechanical analysis..The main methods are grooving,drilling,and splitting.These methods have large errors and cause damage to the detection parts.Therefore,non-destructive testing must be developed.In the nondestructive testing of residual stress,there are mainly X-ray diffraction method,neutron diffraction method,hard X-ray diffraction method of high-energy synchrotron radiation,etc.,but all have disadvantages such as high cost,small detection thickness,and difficulty in commercial use.Short-wavelength characteristic X-ray diffraction technology has the characteristics of low cost,high detection accuracy,and large detection thickness.It’s just that the development of this technology is not complete at present,especially in the positioning and orientation of the detection parts,there are disadvantages of low automation and manual positioning and orientation.Therefore,the development of an automatic positioning and orientation system for inspection parts is of great significance for improving the detection accuracy and efficiency of residual stress non-destructive testing.Aiming at the short-wavelength characteristic X-ray diffraction technology’s shortcomings in positioning and orientation,this paper has developed an automatic positioning and orientation system for residual stress non-destructive testing and conducted verification tests.The main contents are as follows:(1)The automatic positioning and orientation system of the residual stress nondestructive testing equipment is constructed.In view of the application characteristics and requirements of the short-wavelength characteristic X-ray diffraction technology,the coordinate value of the detection point can be obtained by obtaining the surface position information of the detection part through a discrete detection part model or directly using a three-dimensional scanner.(2)The algorithm for obtaining the normal position of the detection point and the continuous positioning and orientation of the detection point is studied.According to the obtained coordinate information of the inspection piece.The curve fitting method is used to obtain the normal position of the detection point to provide data for future orientation;using the European rigid body transformation method,a set of continuous positioning and orientation algorithms for multiple detection points are designed.(3)Completed the short-wavelength characteristic X-ray diffraction technology residual stress non-destructive testing equipment,the test of the positioning and orientation system,and verified the effectiveness and accuracy of the system.Perform positioning tests on multiple detection points in a simple plane and multiple detection points in multiple planes and curved surfaces,respectively.The test results show that this positioning and orientation method can meet the needs of detection,and the positioning error is less than 0.02 mm.