Machining process modeling

H.A. Nied, M.S. Lamphere, Electrochemical Airfoil Machining Process Model, Presented at the Gas Turbines Aero Engines Congress and Exposition, Texas, June 5-8, 1995. 

In subsequent work by Ganapathy and Jawahir (1998), a force model was proposed for cyclic chip formation involving chip breaking. The additional force imposed on the machining process model due to the free-end of the chip contacting the workpiece results in a shift in the... 

In order for a process to be controllable by machine, it must represented by a mathematical model. Ideally, each element of a dynamic process, for example, a reflux drum or an individual tray of a fractionator, is represented by differential equations based on material and energy balances, transfer rates, stage efficiencies, phase equilibrium relations, etc., as well as the parameters of sensing devices, control valves, and control instruments. The process as a whole then is equivalent to a system of ordinary and partial differential equations involving certain independent and dependent variables. When the values of the independent variables are specified or measured, corresponding values of the others are found by computation, and the information is transmitted to the control instruments. For example, if the temperature, composition, and flow rate of the feed to a fractionator are perturbed, the computer will determine the other flows and the heat balance required to maintain constant overhead purity. Economic factors also can be incorporated in process models then the computer can be made to optimize the operation continually. 

The surface smoothness of the machines in the machine building industry is of the order of a tenth part of a millimeter. Welded parts on such a machine must be processed as the welding may be 2 mm or more thick. To reduce this thickness to the lowest possible measure and to save electrodes and avoid additional machine processing of the welding, an experiment has been designed to model the influence of welding parameters on welding thickness. Factors and varia-... 

The process meta model introduces the language (or meta schema) for process model definitions. The meta model is based on djmamic task nets. It provides meta elements for structural (tasks, control and data flows etc.) and for behavioral aspects (e.g. state machines for tasks) of these task nets. 

A drawback of semi-formal models is their limited utility for computer-based apphcations such as analysis, simulation, or enactment. For this purpose, formal, machine-interpretable models are required. However, the creation of formal models is difEcult, time-consuming and requires expert skills. Consequently, a methodology is required for the creation of formal work process models by means of an incremental approach with active participation of all stakeholders. This transfer project envisions... 

The design task is to determine the amount of heat recovered from the heat sources of the process to the heat sinks, that is, to estimate the size of heat exchangers and the amount of external energy needed for heating or cooling of the effluent coming from the paper machine. Both summer and winter scenarios are included in the model by combining two parallel process models for summer and winter conditions that are solved simultaneously. Ambient air/water temperatures are 20/20 °C and -5/2 °C for summer and winter, respectively. 

M.-S. Han, B.-K. Min, S.J. Lee Modeling gas film formation in electrochemical discharge machining process using a side-insulated electrode. Journal of Micromechanics and Microengineering 18 (2008), 045019. 

Machine capability model a computer model that captures the process capability of a machine tool. 

Using these task models without incorporating human and machine models forces a general assumption that task difficulty is a hnear function of complexity (modeled as more task-steps or information requirements). Even with this assumption, the task model by itself provides no indication of the acceptability of the task complexity or expected human or machine performance. Both these judgments require considerations of human and machine processing and performance models. 

Making applied decisions involves performing a combined human machine task analysis of available and required mental capacities. This analysis (1) requires that the mental components of tasks, the mental capabilities of humans, and the information-processing capabilities of machines be modeled and analyzed in compatible and consistent terms and (2) is greatly enhanced if the terms are quantitative. From the... 

SpecTRM-RL explicitly shows the process model used by the controller and describes the required behavior in terms of this model. A state machine model is used to describe the system component s process model, in this case the state of the aircraft and the air space around it, and the ways the process model can change state. 

Unlike other subtractive machining processes, Generative Processes buUd parts by a layer-by-layer technique using form neutral substances like fluids, powders, foil-or wire-shaped materials by chemical and or physical reactions. In general the process, as shown in Fig. 79, results directly from a 3D model, which is sliced into thin cross-sections typically with a thickness of 0.1-0.4 mm. Depending on the kind of process, parts that may be difficult or even impossible to fabricate by conventional methods, can be produced out of polymers, metal, ceramic or composite materials [101]. A selection of RP-processes is described below, but due to the complexity of the processes readers are referred to the cited references. 

---