Research On Several Issues That Affect The Repeated Positioning Accuracy And Reliability Of Manipulator Cold Storage

With the development of industrial automation,the manipulator has become an important tool to replace people to accomplish dangerous and heavy work.Compared with the traditional manual access mode,the manipulator can achieve more efficient and accurate access to the goods and protect the personnel from low temperature injury.There are still some problems in the manipulator cold storage that affected by such as thermal deformation of metal and the change of temperature field in cold storage.At present,because there are few engineering analysis and research for manipulator cold storage.Therefore,it is of great significance to analyze and study the problems existing in the cold storage of mechanical manipulator and propose solutions.In this paper,a manipulator cold storage is taken as the research object.The deformation of the manipulator at low temperature and the change of the temperature field in the opening process of the cold storage have been analyzed from the theory.Deformation of manipulator and shelf and the change of temperature field in the process of opening the cold storage are analyzed through ANSYS and FLUENT,and the simulation results are compared with the experimental data.Meanwhile,by summarizing the experience of the predecessors and combining the actual engineering cases,the other problems in the cold storage of the manipulator are analyzed.The main work and results of this article are as follows:(1)On the basis of a summary of the research status of low temperature thermal expansion of manipulator,shelf and its components at home and abroad,By establishing the thermoelastic structure model of the manipulator and the shelf,the static analysis and study of the strain displacement at low temperature are carried out.Using ANSYS to calculate the strain displacement at low temperature of the manipulator and the shelves,and through the deformation monitoring experiment of shelf,to verify the accuracy of the simulation results of shelf elastic buckling deformation,the influence of strain displacement at low temperature of different types of fixed shelves,it is found that the shelf with the bottom fixed middle and free expansion at both ends has the minimum temperature strain displacement.(2)Based on the analysis of the temperature strain displacement of manipulator and shelf,the positioning error between the manipulator and the shelves are analyzed by the dimension chain principle,and the influence of different fixations on the positioning erroris discussed.It is founded that the positioning error is minimal when the shelf is fixed at the bottom in the middle.(3)Based on the basic theory of heat transfer,the FLUENT finite element analysis software is used to simulate the change of temperature field in the process of opening the cold storage.The veracity of the simulation results is verified by the test of the temperature monitoring of opening the door of the cold storage.The influence of different opening positions on the temperature field of the cold storage is discussed.It is found that the cold storage of the manipulator at the top opens the minimum effect on the temperature field in the cold storage.It is found that the effect of the top of the door on the temperature field in the cold storage is minimal.(4)On the basis of the analysis of the change of temperature field in the process of opening the cold storage,and it was found that the slider placed at the bottom of the cold storage was less affected by the frost.For truss type manipulator,its rolling linear guide pair is easily affected by the frosting condition.Therefore,in order to improve the reliability of the manipulator,the V-shaped guide rail and slider should be used.