| Shanghai Synchrotron Radiation Facility(SSRF)is the first third generation synchrotron radiation device in China,which is mainly composed of light source,beam line and experimental stations.SSRF plans to build a Biological protection protein crystallography beam line(P2 beam line)in the ?-period project,in order to effectively reduce the beam divergence,it needs to use an elliptic cylindrical focusing mirror whose length is 1m,the main content of this paper is using a double pull rod bending mechanism to bend a plane mirror into an elliptical mirror we want.The specific research contents are as follows:(1)According to the beam's bending theory of material mechanics,analyzing the bending moment and the slope error of the horizontal focusing(not considering gravity)and the vertical focusing(considering gravity),we can get the following conclusions,horizontal focusing(not considering gravity): The Bending moment M1=35.04N·m,M2=40.03N·m,the slope error is 0.02?rad,vertical focusing(considering gravity): M1=27.91N·m,M2=32.89N·m,now the slope error is the least which is 0.72?rad.The effect of gravity on vertical focusing is greater,so next the method of gravity compensation is also analyzed.When suing three-point compensation,using the plane as the reference,the error caused by gravity can be reduced to about 0.07?rad.(2)Using ANSYS workbench software to analyze the bending mechanism,we can get rod displacement which can bend the mirror into the desired shape,conclusions: In horizontal focusing,rod displacements were 9.2 mm and 10.1 mm,now compared with the theory of elliptic the slope error is 0.35?rad;In vertical focusing,rod displacements were 7.4mm and 8.4mm,the slope error is 0.88?rad,the error is larger than we want,so the gravity compensation device is required;When using three-point gravity compensation,loading appropriate force,finally we get the rod displacements were 9.1mm and 10.1mm,the slope error is 0.45?rad,it can meet the design requirements.(3)Testing the bending mechanism by the nano-radian Long Trace Profiler(LTP)made by SSRF.Finally,an elliptical surface whose slope error is 0.48?rad compared with the theoretical shape is obtained,and the rod displacements were 9.1mm and 10.9mm.This shape can meet the requirements of the beam line.Then,the repeatability and stability were tested when bending elliptical cylinder.When the repeatability was measured,the mean square error of the object distance was 0.053 m,and the mean square error of the image distance was 0.013m;when measuring the stability,the object distance had a mean square error of 0.099 m,the mean square error of the image distance was 0.024 m.From the measurement results,it can be seen that the repeatability and stability can meet the requirements when bending elliptical cylinder.Finally,the resolution,stability and repeatability were tested when bending cylindrical surface.The resolution of the measurement was as follows: when the displacement of the pull rod was 7mm,the average value of the sensitivity was 6.75 m if the displacement was changed by 0.01 mm,and when the rod displacement was 5mm,The mean value is 13.75m;from the repeatability measuring results,we can get the radial mean square error is 6.24m;when the stability is measured,the mean square error is 6.9m.All of them can meet the requirements.This paper focuses on the study of elliptical cylindrical bending mirror.In the process of study,the analysis of mechanics of materials,the finite element analysis of the double bar bending mechanism's bending model,gravity compensation analysis have been completed.And then using the nano-radian Long Trace Profiler(LTP)to test the actual bending process.The testing results can satisfy the requirements of the beam line,which provide important theoretical and experimental basis for the engineering design of the beam line. |
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