Abstract: Reverse Engineering is a technology that generates a virtual representation of an existing part based on point data acquisition with measuring techniques. Different technologies could be employed to obtain a virtual representation of a physical model, but the use of a solution (3D scanner) rather than another, could provide significant different results because the available 3D scanners are characterised by different performances (resolution, accuracy,. ..). The selection of the right 3D scanner could guarantee an improvement in the points acquisition precision, but it could not assure an efficient points distribution in term of number and locations. These two parameters make part of the acquisition strategy, that should provide a consistent sampling plan. For this reason this paper wants to propose a methodology to define a selectively sampling plan, with grid dimensions related with the complexity of the local surface region analyzed. © 2008 IEEE.

Keywords: 3D Scanner | Free-Form | Reverse Engineering

Abstract: Numerical analysis of metal cutting operations is increasingly relied upon in computer experiments, in order to clarify mechanical, thermal and tribological aspects in view of process optimization. The acid question is, however, whether impressive color displays and detailed figures describe what is actually taking place, or if some results might more properly belong to virtual reality. A classic experimental design for second order response surface work, concerning a simple cutting operation on mild steel, was run both in the metal cutting laboratory and on dedicated software, and results compared also in the light of classic models. Agreement concerning responses such as forces, temperature, and cutting ratio, was found to range from definitely fair to quite poor, underlining that reliance on numerical model may not always be fully justified. Analysis of deviations throws some light on a complex situation.

Keywords: Metal cutting | Numerical simulation | Turning experiments

Abstract: This paper concerns the automatic evaluation of Young's modulus of metallic materials. A procedure has been developed to support the experimental measurement process. A calculation scheme for an evaluation of the overall uncertainty of modulus value is presented according to ISO/IEC/OIML/BIPM guide published by ISO TAG4/WG3. Some numerical experimental results are also provided.

Keywords: Data acquisition | Metallic materials | Young's modulus

Abstract: Damage build-up leading to wire breakage occurring, either during the drawing process or delayed, causes quite a concern for manufacturers and users alike. In multipass wire drawing accumulated strain is known to lead to damage formation and further evolution which, if unchecked, may eventually trigger ductile fracture. However, even for such failures as can be traced back to the combined effect of initial material properties and process induced modifications, reliable assessment of relevant contributions is hardly an easy task at production floor level, and remedial action often relies heavily on cut and try methods.

Abstract: Current studies on mechanics of cold wire Drawing provide a comprehensive picture of the effects of main parameters on he basic process. However at production floor level multipass Drawing still exhibits a number of tough problems. Scatter in wire properties, defects, lubricant decay, irregular die wear may affect product quality and upset production schedule. By combining experimental evidence with theoretical and numerical models of the basic friction and deformation process into a global description of multipass machine operation, taking into account stochastic process properties, production planning procedure may be effectively supported, and reliable guidelines for process control and troubleshooting are obtained. © 1991 CIRP.

Keywords: Drawing | Simulation | Wira

Abstract: Provision for reliable gripping action is a key factor for industrial application of high speed turning. High speed Machining in production requires safety against burst and adequate gripping over the operating range. The present work is subdivided in two parts. In the first one numerical stress analysis with FEM of main components, under both static and dynamic loads, is described as well as spin test up to rupture speed for design optimization purposes. The second one deals with an in-process gripping force measuring device especially designed to operate in a closed-loop regulation system. Results obtained in the course of an experimental investigation and problems concerning dynamic gripping action are discussed. © 1985 CIRP.

Abstract: Design data for a family of ring-shaped elastic elements are derived using analytical, numerical and experimental methods. The development of a family of elastic elements for load cells operating at medium to low load level is considered in detail, using several approaches. Snapes analyzed were circular ring with integral bosses and 'square' ring. The effects of thickness, boss size and fillet radius (reduced to nondimensional form) on strain/load and defiection/load relationships are evaluated within a given sample space, considering a two-dimensional problem. Thin-ring and curved-beam theory support the analytical approach, with correction terms covering some departures from theoretical shape. Numerical analysis with the finite-element method was mainly used to evaluate the effects of boss size and shape. Accordingly, the required grid patterns were developed using a mesh-generating method capable of covering the range of parameters considered. A set of configurations was selected, enabling single and combined effects to be analyzed with little entanglement between estimates. For the square ring, frame theory and a limit solution for the case of the plate with central hole are resorted to. Photoelastic tests were performed, covering a range of shapes by sequential remachining of the model, and equal contigurations were analyzed with the finite-element method. Strain-gage tests on actual elastic elements were made, considering also the results of a series of tests carried out at the Metrology Institute some time ago. Results obtained yield comprehensive information on the effect of several parameters on the load-output transfer function of ring-shaped elastic elements. © 1981 Society for Experimental Mechanics, Inc.

Abstract: A tool-life model based on the assumption that wear and fracture are the causes of tool death is re-examined from the theoretical standpoint, and extended to include the effect of cutting speed on the fracture-induced failure rate. A stochastic model for multi edge cutting tools is also proposed. This enables the overall statistics to be derived from the data for each individual cutting edge. © 1981 by ASME.

Abstract: A tool-life model based on the assumption that wear and fracture are the causes of tool death is re-examined from the theoretical standpoint, and extended to include the effect of cutting speed on the fracture-induced failure rate. A stochastic model for multi-edge cutting tools is also proposed. This enables the overall statistics to be derived from the data for each individual cutting edge.

Abstract: Design data for a family of ring-shaped elastic elements are derived using analytical, numerical and experimental methods. The development of a family of elastic elements for load cells operating at medium to low level is considered in detail, using several approaches. The effects of thickness, boss size and fillet radius (reduced to non-dimensional form) on strain/load and deflection/load relationships are evaluated.

Abstract: In some machining operations tools may fail suddenly in a catastrophic way. Multi-tool setups, where several tools are engaged simultaneously and a single tool failure may impair the whole operation, are particularly sensitive to such a failure mode. Selection of tool replacement strategy may then become a major problem, whose solution is often hampered by scarcity of data. Sometimes no optimal strategy may exist, and little can be done acting on tool replacement only to improve the situation. However, given a minimum amount of information, simple simulation methods help to assess effectively alternative policies. © 1979 ASME.

Abstract: A method developed for the attainment of economic objectives in single-tool machining operations is extended to multi-tool machining. The stochastic nature of tool life is taken into account, as well as the uncertainty of available information, by introducing confidence level for tool life among the parameters considered. Time and cost penalties due to sudden tool failure are also taken into account. An example pertaining to a simple machining operation shows that under the conditions selected the minimum cost region falls well over the ninety per cent mark of confidence level for tool life. © 1979 ASME.

Abstract: A method developed for the attainment of economic objectives in single-tool machining operations is extended to multi-tool machining. The stochastic nature of tool life is taken into account, as well as the uncertainty of available information, by introducing confidence level for tool life. Time and cost penalties due to sudden tool failure are taken into account. An example shows that the minimum cost region falls well over the ninety per cent mark of confidence level for tool life.

Abstract: In some machining operations tools may fail suddenly in a catastrophic way. Multi-tool setups, where several tools are engaged simultaneously and a single tool failure may impair the whole operation, are particularly sensitive to such a failure mode. Selection of tool replacement strategy may then become a major problem, given a minimum amount of information, simple simulation methods help to assess alternative policies.

Abstract: Practical third order experimental designs, developed taking into account the requirements of calibration work, are presented in this paper. These designs are made up by a suitable combination of low order fractional factorials and a symmetric star. Design criteria and performances are assessed and the effects of experimental design on precision of estimation are analyzed.

Abstract: This paper deals with an experimental approach to the voltage-current relationship in the gap during electrochemical operations. Until now, information about the real form of the nonlinear law connecting these two variables has not been available. An experimental setup was built in order to readily collect data in a form suitable for further statistical analysis. Experimental data were obtained according to a factorial design of the 3**n series. Statistical analysis of the results led to a first approximation linear model. Analysis of residuals and theoretical considerations provided clues for a more sophisticated equation which yields a better fit.