Analysis of the Effects of Machining Loads on Online Values of Reaction Forces in Fixture Locating System

The magnitude of reaction forces in locating points is considered as one of the basic parameters in the fixture planning and element design stages of the fixture design procedure. The magnitude of these forces depends on the intensity, position, and orientation of the transient clamping and active machining forces and torque. Analysis of the effect of machining force and torque on reaction forces is a complex process because the magnitude, position, and orientation of machining loads change at any given time. In this paper, an analytical model is presented to investigate the effect of machining loads on online values​​ of reaction forces in the contact points between the workpiece and the fixturing elements. The magnitude ​​and direction of machining forces and torque are calculated on the tool path and using these parameters as inputs to the analytical model, the reaction forces are calculated in each of the six locators at each moment. A finite element analysis is performed to validate the values predicted by the analytical model. For this purpose, the necessary subroutines are prepared and the values ​​of the reaction forces obtained from the simulation are compared to their corresponding values ​​from the analytical model. A three-dimensional workpiece with a 3-2-1 locating system was used as a case study to evaluate the performance of the proposed model. The maximum error in calculating the reaction forces was obtained as 10.85% from the proposed analytical model which indicates the accuracy of the theoretical predictions.