The Planning Of Clamping Forces In Entire Region Based On Clamping Surface Of Complex Parts

Investigation on the reasonable planning of clamping forces in the machining process is the key issue for guaranteeing the machining quality.It is of great significance to ensure the reliability of the clamping forces and accuracy of the Workpiece in the carrying out of machining process.Therefore,the reverse direction iterative planning algorithm of clamping forces in entire region is established.In addition to the direction constraints of contact forces between the workpiece and fixels,the forced status of the workpiece in fixturing layout is analyzed.According to unknown and known condition of magnitude and placement of clamping forces,the analysis methods of force existence and force feasibility are established with connection of the linear programming technology.Under the existence condition of clamping forces,by discretizing the clamping surface into points,the magnitude of clamping force can begin with the minimum value at each point with force existence.The selection of the next magnitude of clamping force is depended on the feasibility difference of adjacent two points.with a certain step along the positive direction.According to the feasibility difference of the current selected clamping force with the last one,the step and its direction can be determined for the next selection.If the feasibility of the current magnitude is same as the feasibility of the previous magnitude,the step and its direction for the next magnitude is same as the current magnitude.Otherwise,it is chosen with the smaller step along the negative direction.The selection procedure for the magnitude of clamping force is exceeded until the absolute value of the current step is within the given threshold value,the half step with the reverse direction planning method in entire region can be presented for the clamping force.Because the proposed method can transform the continuous design problem of clamping forces into the discrete one,it can be used for the development of computer aided clamping force design as well as the determination of clamping forces for workpiece with complex surfaces.For the situation that one single clamping force can not make the workpiece stable in the machining process,and it needs multi-point clamping forces.The Iterative Planning Algorithm of multi-clamping clamping forces is proposed.Each clamping forces can be expressed by a resultant force and projection angles.And to determine whether there are at least a set of clamping forces combination of the resultant force so that make the workpiece stability for the iterative standard.If the iteration criterion isthe same as the previous time,the iteration step and the iteration direction are unchanged.Otherwise,the iteration step is reduced and the iteration is reversed.Until the absolute value of the step is within a given threshold.For the parameter selection of iterative planning algorithm,this paper uses the least number of calculation times as the objective function,and the genetic algorithm is used to optimize the three parameters in the algorithm.Aiming at improve the efficiency of the algorithm.The planning of clamping forces in entire region based on clamping surface of complex parts is not only suitable for the workpiece with complex surface,but also can avoid the optimization of the model in the unstable state of the workpiece.It leads to improve the computational efficiency and set standards of selecting clamping point and clamping force,at the same time,provide the basic theory for the reasonable design of complex workpiece clamping layout.The Iterative Planning Algorithm of multi-clamping clamping forces can search out the range of the value of each clamping force under the combined action of multiple clamping forces,and select the force selection standard for the clamping force of the workpiece which needs multi-point clamping.