Distortion control is one of the most important concerns of the metal processing industry, which also includes the fine-blanking technology. Fine-blanking of sheet metal involves metal flow and shearing, which result in complex deformation. Distortion occurs during the removal of parts from the tool due to the relaxation of internal stresses. Internal stresses that are generated during fine-blanking have an important effect on the shape and size of parts after fine-blanking. The distortion of ring type products during fine-blanking was analysed by using dimension measurements, microscopic observation and numerical simulation.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 1173087A study was made of the weldability of 4-mm-thick aluminium-alloy 5083 plates using friction-stir welding. A plan of experiments was prepared based on the abilities of a universal milling machine, where the tool-rotation speed varied from 200 r/min to 1250 r/min, the welding speed from 71 mm/min to 450 mm/min and the tool tilt angle was held constant at 2. The factors feed per revolution (FPR) and revolution per feed (RPF) were introduced to get a better insight into the friction-stirring process. Samples for microstructure analyses, Vickers micro-hardness measurements and special miniature tensile-testing samples were prepared. The microstructure was prepared for observation on a light microscope under a polarised light source. A set of optimal welding parameters was determined at a FPR of 0.35 mm/r, at which quality welds can be made with a minimal increase in the weld hardness and an up to 15 % drop in the tensile strength.
F.13 Development of new production methods and tools or processes
COBISS.SI-ID: 12490011Single roll melt spinning is the most commonly used process for the production of rapidly solidified thin metal ribbons. Microstructure development over the ribbon thickness mostly depend on the ribbon thickness itself, contact resistance between the melt and chilling wheel, heat transfer in the melt and the wheel, and nucleation and crystal growth characteristics of the particular casting material. The calculations show that contact resistance between metal melt and chilling wheel has a great influence on melt cooling and wheel heating rate, and must not be neglected in heat transfer calculations, even if its value is very low. New method for determining contact resistance through variable heat transfer coefficient is introduced which takes into account physical properties of the casting material, process parameters and contact time/length between metal melt and chilling wheel. It can be concluded from the results that process parameters which determine the thickness of the melt puddle in the downstream have major influence on cooling and solidifying rate of the ribbon. For the propose of industrial continuous casting of larger material quantities, heat balance of the wheel is calculated and influence of the chill wheel cooling mode on cooling rate of metallic ribbon is analyzed.
F.10 Improvements to an existing technological process or technology
COBISS.SI-ID: 1239903The presented work discusses the applicability of the selective laser melting technique (SLM) in manufacture of removable partial denture (RPD) frameworks with the emphasis on material properties. The paper presents preliminary results of a conducted test of the mechanical properties of the F75 Co-Cr dental alloy used with selective laser melting. Analiza mehanskih lastnosti zlitine F75 Co-Cr za uporabo pri selektivnem laserskem taljenju (SLT) izdelave delnih zobnih protez.
F.07 Improvements to an existing product
COBISS.SI-ID: 1173599Investigation deals with the superplastic properties of an AA5083 (Al-4Mg-0.6Mn) with added scandium and zirconium. The investigated alloy was produced by ingot casting and thermomechanically treated with hot and cold rolling into a sheet with a thickness of 1.4 mm. The superplastic properties of the alloy were investigated in tensile tests at strain rates in the range 3x10-4 to 1x10-2s-1 and at temperatures from 470 to 570°C. We examined the true stress, true strain characteristics, the elongation to failure, the strain-rate sensitivity index and the microstructure of the alloy. The elongation to failure increased with the test temperature and was over 1900% at an initial strain rate of 7.5x10-4s-1 and a temperature of 550°C.
F.06 Development of a new product
COBISS.SI-ID: 12167963