摘要 :
A specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced in the paper. The equivalent normal curvature milling model is proposed for generating the tool paths in machining freeform surfaces. ...
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A specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced in the paper. The equivalent normal curvature milling model is proposed for generating the tool paths in machining freeform surfaces. This new milling model can efficiently enlarge the material removal volume at the tip of the milling tool and improve the producing capacity. The machining strategy of this new model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The actual examples for manufacturing the freeform surfaces are given in order to evaluate this milling scheme.
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摘要 :
On the basis of superelement model,Cahn's transformation kinetics theory and Scheil's ad-ditivity rule,the CCT diagrams and transformation kinetics in low carbon steel were predicted considering both undeformed and deformed condit...
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On the basis of superelement model,Cahn's transformation kinetics theory and Scheil's ad-ditivity rule,the CCT diagrams and transformation kinetics in low carbon steel were predicted considering both undeformed and deformed conditions. The influence of deformation on phase equilibria and transformation incubation period was evaluated quantitatively. The recrystallization kinetics and the evolution of dislocation density were calculated during continuous cooling.The results show deformation considerably shortens transformation incubation period, accelerates transformation kinetics and makes CCT curve shift leftwards. The calculated CCT diagrams and the volume fraction of each phase were in good agreement with measurements.
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摘要 :
To simplify the implementation of Maximum Power Point Tracking (MPPT) for off-grid solar applications,a novel control method via load parameters is proposed. The study is based on a simple and effective PV mathematical model in wh...
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To simplify the implementation of Maximum Power Point Tracking (MPPT) for off-grid solar applications,a novel control method via load parameters is proposed. The study is based on a simple and effective PV mathematical model in which the parameters are taken from photovoltaic (PV) module datasheet. The monotonic relationship between PV output voltage and duty cycle of power switch in solar chargers with the form of Buck and single-ended primary inductance converter (SEPIC) is revealed and made it feasible to implement MPPT control by combining battery charging power and power switch duty cycle variations. The disturbance step of duty cycle in perturb and observe (P&O) MPPT algorithm is determined according to the relationship between battery charging power and duty cycle. The dynamic response of the proposed MPPT method is improved by periodic state reset for MPPT control while only small disturbance step of duty cycle is required. Simulation and experiment results are provided to evaluate the feasibility and validity of the proposed control.
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