196,938 research outputs found
Impianto per lavorazioni innovative di lastre di granito con getto d'acqua
No full textAtti del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Università di Pis
GR4: Macchina innovativa per il taglio di materiali lapidei mediante filo diamantato
No full textAtti del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Università di Pis
Liquid-phase Infiltration of Sintered Skeletons by Low-temperature Gold Eutectic Alloys
No full textThe flexibility of powder-based Rapid Prototyping (or Solid Free Form Fabrication) techniques and the densification method described in this paper would open a whole new range of applications where thermal constraints exist. This work examines the infiltration of sintered skeletons made of pure gold spherical powder ranging between 5 and 40 micron in size, by binary gold eutectics based on silicon, germanium and tin, with a melting point as low as 278o C. Experiments have shown that high densification rate, good surface finish and improved mechanical properties can be achieved with this process. The material properties influencing the process performance are pointed out
Integration of hybrid additive / subtractive manufacturing planning and scheduling by metaheuristics
No full textReviewed solutions to model additive manufacturing process planning do not include all types of flexibility required by hybrid additive/subtractive operation. In the proposed system the features are extracted from CAD by a rule-oriented system denoting accessibility, surface accuracy, volume merging by functional relations, including deleted datum; the process planner identifies alternative modes to process the operation (operation flexibility) and allows swaps between operations in the routing sequence (sequencing flexibility); the system core generates a precedence graph of manufacturing features introducing flexibility by both conjunctive and disjunctive arcs and nodes, which can enter any position of a subsequence and ranks them by an antecedence analysis. Parametrized relation allows the precedence graph to be visited by a constructive metaheuristic. An Ant Colony Optimization (ACO) has been validated on properly designed instances and literature benchmarks varying job number, alternative operations and disjunctive arcs of routing. Current model reduces the node redundancy of AND/OR graphs and copes with the increased complexity of integrated process planning and job shop scheduling
Quanto costano le lavorazioni SLS
No full textIl lavoro si propone di effettuare un'analisi preliminare del ruolo giocato dai parametri di processo nella stima dei costi delle lavorazioni SLS su sabbia rivestita e nylon.
Di conseguenza si valuterà quali saranno i parametri opportuni da modificare per ottimizzare la produzione dal punto di vista economico, inoltre si farà un'analisi qualitativa dei risultati delle modifiche
The Process Control in Manufacturing: Inspection of Ball Bearings
No full textA real industrial case has been analyzed and is discussed in this paper. Significant percentage of defective ball bearings is not detected during the final inspection in the only manual station of the automatic assembly line. The main specifications of an inspection system, which is based on artificial vision, are pointed out. The system configuration (camera, lighting and ball bearing support) is described in detail. The visibility of all surfaces has been optimized using one central conic and four lateral mirrors. In off-line tests, the described algorithms allowed the recognition of most surface defects. Interactive and user-friendly calibration procedures have also been defined
Micro slot milling of glass
No full textMicro slot milling micro channels in a single pass vs two step upmilling has the benefit of higher productivity. This problem is approached by showing the theoretical benefits of more than two cutting edges. The acceptable feed per tooth and cutting depth at the maximum undeformed chip thickness for ductile-brittle transition and the benefit of upmilling versus downmilling and other parameters (tool wear, tool trajectory, tool deflection, air pressure/cutting oil) have been assessed by micro and macro-geometrical analyses versus surface finish/transparency, form error of the cross section shape in the micro scale (aspect ratio, tolerances, parallelism, flatness, straightness), chipping and productivity. Quantitative correlation between transparency and roughness is also proposed to estimate the acceptable amount of brittle mode
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