Design, Analysis and Experimental Verification of the Self-Resonant Inverter for Induction Heating Crucible Melting Furnace Based on IGBTs Connected in Parallel

The object of this research was a self-resonated inverter, based on paralleled Insulated-Gate Bipolar Transistors (IGBTs), for high-frequency induction heating equipment, operating in a wide range of output powers, applicable for research and industrial purposes. For the nominal installed capacity for these types of invertors to be improved, the presented inverter with a modified circuit comprising IGBT transistors connected in parallel was explored. The suggested topology required several engineering problems to be solved: minimisation of the current mismatch amongst the paralleled transistors; a precise analysis of the dynamic and static transistors’ parameters; determination of the derating and mismatch factors necessary for a reliable design; experimental verification confirming the applicability of the suggested topology in the investigated inverter. This paper presents the design and analysis of IGBT transistors based on datasheet parameters and mathematical apparatus application. The expected current mismatch and the necessary derating factor, based on the expected mismatch in transistor parameters in a production lot, were determined. The suggested design was experimentally tested and investigated using a self-resonant inverter model in a melting crucible induction laboratory furnace.

RANCANG BANGUN DAPUR CRUCIBLE TIPE PENUANGAN TUNGKIK KAPASITAS 15 KG DENGAN BAHAN BAKAR GAS LPG

This research aims to; 1) Designing and making aluminium melting crucible casting with the capacity15 kg; 2) Conducting the test of chemical composition of the first and second melting result. Theresearch used field and library research. From the result of the design, it could be obtained that thedimension of melting casting has 547 mm diameter, 3 mm thick, 410 mm high. Whereas, molten cup has 178 mm diameter, 8 mm thick, and 230 mm high. The result of the first melting chemicalcomposition test and the second one do not work out a significant change. The material of the firstmelting result still contains 89,52% of aluminium (Al), while the main fusion is 7,71% of zinc (Zn)and 1,84% of silicon (Si), and in the second melting result still contains 89,55% of Alumunium (Al),while the main fusion is 7,51% of zinc (Zn) and 1,94% of silicon (Si).

Researh on the Developments of HFIC Allied Powders

The following paper presents the constructive manufacturing solution for low and medium allied powders in continuous flux, by melting in the caster, using high frequency induction currents - HFIC, wires, base material, and continuously discarding the melt over a rotating drum, cooled at a determined speed, thus by optimizing the movement and cooling parameters we can obtain the proper grain size.The functional model has the capability to achieve alloyed powders within a broad range of grain size, recommended in research. The melting furnace can be supplied with solid wires or tubular wires, with a fill coefficient of up to 0.55%, which allows the composite core to be integrated into the alloying system. Also, due to its high degree of flexibility, the equipment allows the HFIC melting crucible to be supplied with more than two wires at a time, a feature that ensures a high level of alloying of the powders to be achieved.The functional model developed in order to manufacture powders continuously was used to produce alloyed powders, insensible to elements burns when alloyed, by passing them, at welding, through the electric arc. Forwards we present physical-chemical characteristics of two powders destined to develop composite core from tubular wire alloyed with chromium and nickel.Repairing hot molds by the MIG molds made of low alloyed improvement steel requires type Fe-2.5% Cr-4.5W-V materials, with high homogeneity of the composite mixture from the making of powdered core of tubular wires.Repairing the semi-mechanized rotors made of martensitic steels from hydropower plants requires tubular (cored) wires that deposit type Fe-12% Cr-4% Ni alloys, possibly even Mo.

Evaluation of Functionally Graded Ceramic Crucible for Induction Melting of Titanium Based Alloys

During the last years a very significant effort to develop a melting crucible for induction melting of Ti based alloys at competitive cost has been carried out by many researchers, where the authors are included. Results obtained so far have shown that no material accomplishes the melting crucibles two main demands: inertness facing titanium alloys and suitable/enough thermal-shock resistance. Until now, yttrium and calcium oxides were those materials that performed best on what concerns to thermodynamic stability. However, in both cases, crucibles thermal-shock resistance was very poor, and there are references to crucibles that cracked during melting. Besides, calcium oxide reveals manipulation problems, due to its high higroscopicity. This paper concerns to the evaluation of zircon based crucibles with Y2O3 inner layer for induction melting of TiAl based alloys. A novel multi layered crucible production technique based in a centrifugally assisted slip casting process followed by a sintering operation is described, and results concerning to crucibles porosity and wall composition and morphology are presented. Crucibles obtained in different processing conditions were used to melt a Ti48Al alloy which was poured in graphite moulds. Experimental results include alloy chemical contamination with residual elements, mainly yttrium and oxygen, microhardness measurement and the presence of yttrium oxide and zircon inclusions in the cast samples. Results concerning to the crucibles behaviour are also presented with particular attention to cracks development. The Y2O3 crucible layer was found to suffer some erosion and be slightly dissolved by the molten alloy and the extent of those phenomena depends on the porosity of the layer surface, for fixed experimental melting conditions.