Abstract:

Fixturing is firstly confronted in the workpiece machining process. It is more important, stable fixturing is prerequisite to guarantee the machining quality and safety manufacturing. Therefore, an optimal model of fixturing layout and its genetic algorithm-based solution technology are proposed according to the fixturing stability index and stability measurement. Both the conditions for static equilibrium and the linear programming technology above all are employed to conclude the judgment criterion of fixturing stability and the corresponding solution algorithm. Thus, it is possible to describe whether a workpiece is stable in the fixturing process. Secondly, based on the equation of super elliptical sphere of forces, the volume of the super elliptical sphere is defined as the fixturing stability measurement which can measure how stable the workpiece is when it is stable. Finally, the surface discretization is introduced to formulate the optimal model of fixturing layout with the objective of maximizing the fixturing stability measurement. According to the fixturing stability of each generation, the evaluation function is defined for the fitness of the individual. Thus, the genetic algorithm can be skillfully developed to solve the optimal model of fixturing layout. The presented planning methodology for fixturing layout only concern on the coordinates and normal vectors of contact points. Again, it can also avoid the solution of the optimal model under the condition of the workpiece in unstable fixturing. So the proposed method can not only carry out for complex workpieces, but also improve the calculation efficiency. It can provide a basic theory of fixturing layout design for the complex workpiece.

Key words: genetic algorithm, stability index, stability measurement, surface discretization, fixturing layout