微小角中子散射谱仪探测器移动小车驱动机构设计及精度测试

Driving system design and precision test of the VSANS detector trolleys

针对中国散裂中子源(China Spallation Neutron Source,CSNS)微小角中子散射谱仪(Very SmallAngle Neutron Scattering Spectrometer,VSANS)探测器移动小车对重载、大行程和较高定位精度的要求,设计了双导轨导向、齿轮齿条传动的驱动结构,通过高精度伺服电机的控制实现对探测器移动小车的较高精度定位控制。通过激光跟踪仪对探测器移动小车的往返5次定位测试可知,其双向重复定位精度为140μm,定位精度为167μm。测试结果表明:齿轮齿条传动结构能够满足微小角中子散射谱仪探测器移动小车所要求的200μm的定位精度。

[Background]The Very Small Angle Neutron Scattering(VSANS)instrument of China Spallation Neutron Source(CSNS)is a world-class SANS instrument with several detectors.It is necessary that the three 3He detectors move accurately and smoothly forward and backward in the vacuum scattering tank.[Purpose]This study aims to create high-precision detector trolleys with a positioning accuracy of≤200μm in the traveling range of 5 m.[Methods]Three detector trolleys supported by double guide rails with rack-pinion mechanism were designed,fabricated and aligned.They were motorized by three servo motors meshing with the rack-pinion system fixed on one side of the guide rail at the bottom of the detector tank.The rotation of the motors to maintain the smoothness of the action was realized by planetary gear reducer.The parallelism of the left and right sides of the guide rails was controlled within 50μm during the 12 m stroke,and the reverse clearance of the rack and pinion was controlled within 100μm to provide high motion accuracy of the detector trolleys.[Results]The results of five round-trip repeat positioning tests of the detector trolleys demonstrate that the bidirectional repeated positioning accuracy of the detector trolleys is within 140μm,and their positioning accuracy is within 167μm.[Conclusions]Three detector trolleys supported by double guide rails and powered by a rack-pinion mechanism are constructed for the CSNSVSANS instrument.The positioning accuracy is better than 200μm which meets the precision requirements of SANS experiments.