Development of a Finite Element Analysis Tool for Fixture Design Integrity Verification and Optimization 2002-01-0132
Machining fixtures are used to locate and constrain a workpiece during a machining operation. To ensure that the workpiece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped. Minimizing workpiece and fixture tooling deflections due to clamping and cutting forces in machining is critical to the machining accuracy. An ideal fixture design maximizes locating accuracy and workpiece stability, while minimizing displacements.
The purpose of this research is to develop a method for modeling workpiece boundary conditions and applied loads during a machining process, analyze modular fixture tool contact area deformation and optimize support locations, using finite element analysis (FEA). The workpiece boundary conditions are defined by locators and clamps. The locators are placed in a 3-2-1 fixture configuration, constraining all degrees of freedom of the workpiece and are modeled using linear spring-gap elements. The clamps are modeled as point loads. The workpiece is loaded to model cutting forces during drilling and milling operations.
By implementing FEA in a computer-aided-fixture-design (CAFD) environment, unnecessary and uneconomical “trial and error” experimentation in the machine shop is eliminated.
ANSYS Parametric Design Language (APDL) code is used to develop an algorithm to automatically optimize fixture support and clamp locations, and clamping forces, to minimize workpiece deformation, subsequently increasing machining accuracy.