Multi-Objective Optimization Of GMA For Non-Cylinder Hole

The application of non-cylinder hole on piston pinhole can improve the carrying capacity by the greatest extent, so it is an inevitable trend to use this kind of hole on high load piston pin holes. High frequency movement in precise micro-displacement of the tool is required when boring the hole and the displacement of the tool needs to be changed according to its spindle rotation angle and its axial position in boring process, because the hole has a very complex three-dimensional surface. This makes the production process difficult. A new kind of tool compensation device(GMA) driven by giant magnetostrictive material (GMM) is studied to solve this problem. The achievements have been applied in Shandong Binzhou Bohai Piston Co., Ltd. The main work includes:1.Tool compensation devices at home and.abroad for non-traditional pinhole is summarized, and a combination use of GMM bar and flexible hinges as a method is put forward to solve non-cylinder hole boring problem; The current situation of optimization on GMA is summarized too, and it is proposed that to establish the model of the elastic deformed body firstly and then optimize it by genetic algorithm for multi-optimization problem on GMA; The principle of the Modified Non-dominating Sorting Genetic Algorithm (NSGA_Ⅱ) is studied and two ways to deal with unequal constraints among variables are found.2. A elastic deformed body combined of right angle lever and four-bar linkages is designed. which can generate displacement of perpendicular direction to the force. The body is an executive and also pre-load structure of the GMA. and this makes the GMA system more compact, the length of the spindle end hang out reduced, which makes its vibration less.3. Four methods to set up the model of the elastic deformed body is discussed. According to the common requirements of the four methods, the accurate finite element model of the elastic deformed body is set up and auto-loop calculation is accomplished by MAC files. The method based on flexible hinges’model existing at present is tried, but is deserted due to its poor accuracy and finally the second method is used. Firstly key factors is selected, than the finite element analysis method (FEA), curves fitting method, combined with the lever principle, equivalent quality formulas and modal formulas are used, and the static and dynamic model coupled of key factors of the body is set up. The error correction model of equivalent mass is brought up, and correction parameters are optimized by NSGA_Ⅱ to ensure the accuracy of dynamic equation.4. Multi-optimization of the deformed body is accomplished by NSGA_Ⅱ, and the optimal solution is gained. The objectives includes:the output displacement considering the elastic deformation of the GMM bar, its output force, its magnetosrictive coefficient, the output displacement and the first order natural frequency of the deformed body. Experimental study is conducted, it is proved that the GMA has high high positioning accuracy and repeatable positioning accuracy, and the cure of pinhole is smooth. The GMA can meet requirements in production process.