Research On The Miniature Parts Assembly And The Effect Of Adhesion Force On Reliable Operation

Parts assembly is the important session of the manufacturing process of miniature inertial devices, which directly affects the performance of the devices. Assembly with reliability ensures the application of miniature parts assembly system device. With the miniaturization of parts, surface force has an increasing impact on parts pick-up and release, especially in the release process, the position errors due to the surface force between the adsorption head and part will affect the assembly accuracy, thus reliable pick-up and release of parts is the key to the success of miniature inertial devices assembly.The miniature inertial devices which need to be assembled in this paper consist of seven parts, and three of them are sheet-type parts and minimum quality of these parts is 0.4g, we use vacuum adsorption to pick up these three parts. In order to reduce the effects of adhesion force on the precision of part-assembly, We analyze the van der Waals force, electrostatic force, and capillary forces respectively:the three kinds of adhesion force. And we study the generating mechanism of various forces and influence factors, providing theoretical guidance for reducing adhesion force to some extent.We design and build a device to measure the adhesion force in contact surface between the adsorption head and part during the assembly operations, in response to above-mentioned three parts, we reveal the effects of different separation speed, the load assembly force and time, different adsorption head material and ambient humidity on adhesion. The measurement results show that the separation speed and the load assembly force time have major effects on the adhesion force between the rubber adsorption head and silicon, gilt material parts respectively. In both case the adhesion force increases significantly as the value of the two parameters increase. However, the two parameters have weak effect on the adhesion force between the adsorption head and aluminum material part. When the load assembled force range within 20-80mN, the adhesion force between the rubber adsorption head and three kinds of material parts remain stable. Also, adsorption head of polytetrafluoroethylene (PTFE) material can significantly reduce the adhesion forces on the three parts. Ambient humidity affect the adhesion of the surface between the rubber adsorption head and parts of three materials significantly. The adhesion increase as humidity significantly increases, but when the humidity is higher than 60%, the adhesion force between the rubber adsorption head and silicon material part becomes stable.Through experimental results, we know that when picking up miniature parts, we should execute in a low humidity environment, use adsorption head with PTFE material and select a smaller value within a suitable separation speed and load assembly force time tend to reduce adhesion force and improve the precision of the system assembly.The assembly process of the systems now is pure, and the system is inflexible. Aiming at these, this paper optimizes the assembly process based on current one and developed an assembly process with different parts. Also, we develop a control software program for precision assembly system on the Microsoft Visual C++ platform. The system can choose from any part to start the subsequent assembling task of the entire assembly. Fitting experimental results shows that the optimized assembly software can effectively improve the efficiency and flexibility of the system assembly.