The Mechanical Characteristics And Precision Analysis Of Flexible Automatic Assembly System For Micro Devices

With the continuous development and application of micro precision mechanica l systems in aerospace,military and other fields,the assembly requirements for non-silico n MEMS devices and 3D complex micro parts are increasing.Non-silicon MEMS devices are generally small in size,easy to damage and light in quality.The traditional manual and semi-automatic manual assembly is inefficient and the assembly quality is not high.Therefore,the research of automatic assembly technology for non silicon MEMS devices and 3D complex micro parts are of great significance.On the basis of the first generation micro assembly system,our team developed the second generation micro assembly system for micro structure devices.In this paper,as a part of the overall research content,the aim is to analyze the mechanics characteristic and the precision of the micro assembly system,ensure the accuracy and stability of the micro-assembly systems,but also provides technical support for high precision automatic assembly precision micro system.The main contents are as follows:(1)Static characteristic analysis of assembly unit in microassembly system was carried out.The deformation and stress distribution of the two structures after gravity loading were compared by using finite element static analysis of two different types of box body is done by stitching and casting,at the same time the advantages and disadvantages of the two different structures were judged.So the basis for the optimal design of assembly cell structure was provided.Through the modal experiment,the experimental results were compared with the simulation results.The two deviations are smal er and the trend is consistent,which proves the applicability and correctness of the simulation model and method.(2)The dynamic analysis of assembly unit structure of micro assembly system was carried out,adopting the method of combining simulation with experiment.Through the finite element modal analysis,the vibration modes and natural frequencies of the assembly units were obtained,and the reliability of the structural design is verified by the vibratio n modes.Through modal experiments,the experimental results were compared with the simulation results.The two groups of values had little difference and the trend was consistent,which proved the applicability and correctness of the simulation model and method.The value of 1 order natural frequencies obtained by simulation and experiment showed that the base frequency of the assembly unit was high.It was calculated that the critical speed was8965r/min,which was much higher than the maximum speed of the motor in the system,and no resonance phenomenon occured.(3)The overall design scheme of micro assembly feeding system was put forward.The structure of the material tray was designed,and the feeding program of the robot with SDOF was programmed according to the structure of the material tray.Furthermore,according to the pneumatic control principle,the gas circuit schematic diagram and the gas path structure module for the microassembly system were designed.Based on the principle of vacuum adsorption,the adsorption heads for flat micro parts were designed,and the critical pore diameter for reliable adsorption were obtained by d_h=0.5mm.Finally,the vacuum generator was selected according to the calculation of the adsorption response time and the suction flow.The stable and reliable work of the feeding and unloading system laid the foundation for the high precision assembly of the assembly execution module.(4)The assembly accuracy analysis of micro assembly system was carried out.The error sources that may affect the accuracy of microassembly system were expounded,and the secondary factors were eliminated one by one.The main influencing factors are adjustment error,butt assembly error and detection error.Through the experiment,the error of each stage were measured.By establishing the error transfer model,the corresponding error areas were calculated and the theoretical assembly accuracy values were obtained.Finally,the accuracy of the assembly accuracy was proved by the assembly accuracy verification experiment.