The Design Of Fixture And Its Application Management For Automatic Assembly Of Miniature Parts

With the development of micro-assembly technology,the assembly of miniature parts is characterized by high precision,automation,and mass,and it has been widely used in precision components such as accelerometers,gyroscopes,and MEMS sensors.The characteristics of miniature circular thin parts are small size and lightweight.It is difficult to operate,easy to be disturbed,and difficult to recognize and extract contour by vision machine due to occlusion when assembling.The assembly device of such miniature parts mostly requires manual intervention.At the same time,the importance of batch assembly fixture application management is easily ignored.Based on these questions,this paper presents a method of assembling miniature parts,an automatic assembly system was also developed,and the assembly fixture was designed by using the assembly strategy of "from small to big".And a fixture application management method for batch miniature parts is proposed.Firstly,an automatic assembly system is developed,and combining with the assembling method of miniature circular thin parts,study the layout and function of each module of the system.The assembly and locking process of the assembly method of miniature parts are analyzed to verify its feasibility.The influence of installation error on assembly accuracy was considered.The assembly system consists of six modules.The assembly operation arm is used to pick up and place large parts,the machine vision is used for circular thin part identification and contour extraction.The assembly fixture of the feeding platform module determines the layout of each module in the system.It is the key to the assembly automation of circular thin parts.Secondly,the feeding form and locking structure of the assembly fixture is studied.The loading device assembly is designed.The characteristic is that reverse placing and loading in sequence during assembly.The automatic locking device is designed.It is to realize automatic locking and convenient manual disassembly at the same time.A mechanical model of the curvature cantilever beam is presented,and the structure of the circular thin holder is designed by theoretical analysis and finite element simulation.After that,a method of fixture application management for batch miniature parts is presented.The assembly fixture application method includes a data acquisition layer,assembly fixture layer,assembly parts layer,and assembly information layer.Number assembly fixtures so that they have unique identification.Through the assembly information collected by the sensor data,the assembly parts,and assembly fixture establish the association.And the hardware and software of the fixture management method are designed.Lastly,the mechanical properties and visual tests of the designed thin part holder were carried out.The mechanical properties of circular thin parts held for a long time at room temperature and heated at 120℃ for 1 hour were investigated.The assembly manipulator adsorbed the thin part holder and observed whether it affected the contour extraction of circular thin parts under the camera.The experimental results show that the coaxiality between the middle part and the upper and lower parts of a component is better than Φ0.02 and Φ0.04 respectively.This method also provides a new idea for other miniature parts assembly.