The Automatic Clamp Point Planing Technolege Based On Fixturing Stability

With the rapid development of manufacturing industry, the machining technology has been improved. Fixturing is firstly confronted in the workpiece machining process. A workable fixturing layout is prerequisite to guarantee the machining quality and safety manufacturing. According to the rigidity and flexibility of workpiece, the planning method of fixturing layout is proposed for a workpiece.Suboptimal of machining accuracy and surface quality are result of the rigidity workpiece lost their ability to keep static equilibrium which generate play. Therefore, an optimal model of fixturing layout and its genetic algorithm-based solution technology are proposed according to the fixturing stability index and stability margin. Both the conditions for static equilibrium and the linear programming technology are, above all, 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 margin 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 margin. 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.Suboptimal of machining accuracy and surface quality are result of the clamping force deformed flexibility workpiece. Generally speaking, it is difficult to reveal the relationship between the multiple fixturing parameters and the clamping deformation of workpiece. Therefore, an optimal model of fixturing layout and its neural network based clamping deformation prediction are proposed according to the fixturing stability index. In ensuring the clamping stability at the same time, through the construction of BP neural network nonlinear fitting ability with the workpiece clamping deformation minimization model, and using particle swarm optimization algorithm to improve the ability of neural network’s prediction accuracy and generalization, to obtain a prediction method of flexible workpiece clamping layout by neural network.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 carried out for complex workpieces, but also improve the calculation efficiency. it can provide a basic theory of fixturing layout design for the complex workpiece.