| The last stage of the mechanical product’s manufacturing process is usually assembly and the quality of assembly determines the final quality of the product. With the implementation of the strategy of "Made in China 2025", the manufacturing industry in China has stepped into a new period of development, which demands a higher assembly quality. In this paper, with the background of a solid rocket motor(called thin-walled cylinder) automatic tightening machine clamping system, the optimization of the clamping deformation of the thin-walled cylinder was studied. The clamping layout and clamping force of the original clamping system is mainly based on the experience design, and it is difficult to ensure the stable clamping of the thin-walled cylinder for the poor rigidity of the thin-walled cylinder. Hence, there is a need to optimize the original clamping position to minimize the clamping deformation and ensure the assembly quality of thin-walled cylinder.In this paper, the clamping process of thin-walled cylinder was firstly studied. Considering the influence of different clamping jaws on the deformation of the cylinder, the formula of bending moment under the action of different number of symmetrical clamping force was derived from the analysis of internal force of thin-walled cylinder. Taking the current three-jaw clamping schemes as an example,the minimum clamping force to keep the thin-walled cylinder from rotating under the action of tightening torque was calculated and the maximum clamping force that the cylinder can bear was also calculated. And then the relation between the cylinder clamping force and the radial deformation was deduced。Through the mechanical analysis of the cylinder clamping process, it can quickly and reasonably calculate the clamping force of the clamping system, and provide a basis for the optimal design of the fixture in the future.Based on the mechanical analysis of the clamping process and ANSYS finite element simulation platform, the finite element analysis model of thin-walled cylinder was established. And then we had a detailed analysis and validation of deformation rules of thin-walled cylinder under the action of three-jaw and multi-jaw symmetrical clamping force, founding that the simulation results meet mechanical analysis results well which indicated that the increase of numbers of the clamping jaws would help reduce the clamping deformation of cylinder. In addition, we had a simulation analysis on the effect of changing size of clamping jaw on deformation of thin-walled cylinder. The simulation results show that the increase of the width of the jaw can effectively reduce the clamping deformation. According to the current three-jaw clamping layout, we had a detailed analysis of the deformation rule of thin-walled cylinder under the action of tightening torque and three-jaw symmetrical clamping force with ANSYS’s contact analysis ability in the real clamping process, which lay the foundation of the optimization of clamping position.According to the basic principle of particle swarm optimization algorithm, the application of particle swarm optimization algorithm in the optimization of the thin-walled cylinder was introduced in detail. And a joint simulation system of clamping optimization based on ANSYS and MATLAB was established by analyzing the communication method of data between ANSYS and MATLAB. In order to minimize the clamping deformation of the thin-walled cylinder, the optimization model of the thin-walled cylinder was established, and then the clamping position of the thin-walled cylinder was optimized based on the particle swarm optimization algorithm and the finite element method. At last, the effect of clamping deformation before and after optimization was compared, the simulation results show that the new clamping positions based on the particle swarm optimization can effectively improve the clamping deformation of the thin wall cylinder which could achieve a better clamping effect. |
