| Adhesive bonding technology is another connection mode which is different from welding and threaded connection mode in micro-assembly. There’s many advantages of this kind of connection mode such as do not heat, simple process and do not need other auxiliary process, besides this method can be used in different materials which are not thermo-match. Adhesives possess elasticity which can ensure the bonding precision when the environment changed. As adhesive bonding technology is widely used in micro-assembly field, the requirement in precision, uniformity and bonding quality are improving as well. As the core technology of the adhesive bonding technology-the fluid dispensing technology decides and restricts requirements above. However, the present fluid dispensing is difficult to dispense high viscosity adhesives, especially the dispensing technology used in aerospace field has disadvantages of low automation level, bad uniformity and low efficiency. Therefore, this paper develops an automatic precise jet fluid dispensing equipment, which possesses advantages of simple structure, high uniformity and can achieves high viscosity adhesives precise dispensing.This equipment is mainly consisted of a dispensing system, a3-DOF manipulator, a vision measurement system and a industry personal computer. The dispensing system composed of a dispensing valve, pressure source and a dispensing controller. Dispensing valve with servo structure squeezes out adhesive through pressure source, and press off adhesive through the internal pin controlled by air valve, so as to dispense adhesive. The thermal assisted device is arranged at the bottom of the dispensing valve, which is used to control the temperature of the internal adhesive, so as to achieve to dispense the adhesive from low viscosity to high viscosity.3-DOF manipulator is consisted of precise guide rails which are driven by servo motors, and the IPC is used to precisely fix position for dispensing valve. Vision measurement system is integrated to further ensure accurate position of the dispensing system, and collect the image of the droplets, by means of image processing can measure and control the shape, and effectively supervise the uniformity of the droplets, and take the contact angle measurement to measure the volume of the tiny droplets Through the fluid dispensing test by control the temperature, viscosity, air humility and driven air pressure achieved a kind of high viscosity adhesive which is used in aerospace precision instrument elements bonding, and obtained the optimum process parameters. Through researching distribution temperature of the adhesive inside the cavity by using the finite element analysis software ANSYS Workbench, the influence of the temperature distribution to the uniformity has been analyzed, the velocity distribution of the adhesive inside the cavity has been analyzed, and the velocity of the adhesive at the nozzle outlet point has been gotten with the software ANSYS Fluent. |
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