This paper describes the initial development of an Internet-based application, 'Machinist Online', that will allow process planners to select high-speed milling parameters for maximized material removal rates in a science-based pre-process manner, rather than relying on experience. The primary mechanism for realizing this capability is dynamics prediction for the tool/holder/spindle/machine assembly using Receptance Coupling Substructure Analysis, or RCSA. This method analytically predicts the assembly response by combining models and/or measurements of the individual components through empirically-obtained connection parameters. Currently, a primary impediment to full implementation of the academic research in high-speed machining, particularly linear and nonlinear chatter (or unstable machining) models, at the production level is the necessity of measuring each tool/holder/spindle/machine frequency response, typically by impact testing where an instrumented hammer is used to excite the structure and the response is recorded using an appropriate transducer, such as an accelerometer. The chatter models, which can be used to select cutting conditions for both dramatic increases in material removal rates and improved part accuracy, require knowledge of the system frequency response as reflected at the tool point. Due to a potential lack of engineering support and sometimes limited knowledge of dynamic testing procedures, the frequency response measurements are rarely carried out, especially at Tier I and II manufacturing facilities that fabricate a large fraction of the total number of US discrete parts due to outsourcing from major automotive and aerospace manufacturers. Therefore, the well-established stability improvement technology (i.e., stability lobe diagrams, which separate stable and unstable cutting zones graphically as a function of chip width and spindle speed [e.g., 5-10]) afforded by high-speed machining is very often not applied. The result is reduced process efficiency and part quality and increased cost.
展开▼
