Research On Magneto-rheological Fluids And Design The Structure Of Flexible Fixture Based On MRF

With the rapid development of machinery industry, flexible manufacturing systems become an important development direction. How to develop the flexible fixture has become has become an important issue in modern manufacturing, and has get more and more attention. In this paper, considering the technical requirements of flexible fixture, the merit of magneto-rheological fluid(MRF) and the characteristics of pneumatic transmission system, A new type structure of flexible fixture has brought forward, with the modular thimble MR damper as a positioning mechanism, pneumatic drive for the clamping device. Combining the application of flexible fixture features, The paper completed the design, theoretical analysis and experimental study of flexible fixture, including the MRF for flexible fixture, magneto-rheological damper thimble structure and characteristics of damping force, pneumatic transmission system used for the clamping device, flexible fixture integral structure etc. The main contents are as follows:1. Analyzing the components characteristics and flow mechanism of the MRF, the influence was researched on the settlement and the shear yield stress of the MRF by the volume content of the ferromagnetic particle, silicone oil viscosity and additive. Then used the single factor experiments, the new additive combination--titanate coupling agent and silane coupling agent was chosen in 6 kinds common additives. The mechanism was depth studied on the silane coupling agent and titanate coupling agent. Finally, According to the test conclusions, combined with the needs of flexible fixture application.and using orthogonal experimental method, a kind of MRF was successfully developed which has the high shear yield strength and good sedimentation stability.2. Combined with flexible fixture design principle, using MR damper thimble for positioning, the scheme of flexible fixture was overall designed for Processing of thin-walled workpieces.3. The work mode of magneto-rheological damping thimble was determined. the structure and magnetic circuit of damper were preliminary designed, and the parametric finite element thimble model was established. Using magnetic solid coupling finite element method and the first-order optimization method, the thimble structure was optimized which used the damping force as optimizing targets in the software ANSYS. Based on the optimization results, the thimble unit was designed and manufactured. Through the fluid-structure coupling analysis method, the damping force performance was analyzed on the magneto-rheological damper thimble, And filling homemade magneto-rheological fluid, the damping force of thimble were measured. Experimental results show that the experimental damping force characteristics of optimized thimble basically tally with simulation damping force, which provided reference for the engineering application of thimble4. The composition clamping device was introduced and the clamping forces was determined, According to the needs of flexible fixture and the advantages and disadvantages of clamping device, pneumatic transmission system was selected as the clamping device of flexible fixture. By expounded the principle of pneumatic transmission, the pneumatic system scheme was drafted, Then pressure transmission system was designed which used in flexible fixture, and the key parameters were calculated, that completed the important part of flexible clamp design.