Continuous Rotary Extrusion (CRE) of Flat Sections from 6063 Alloy

The study relates to a process of continuous rotary extrusion (CRE), also known under the name of a Conform Process. This method is used more and more extensively for the plastic working of metals and alloys. In CRE, the feedstock is fed into a profiled groove on the rotating extrusion wheel and is pressed by the pressing wheel. The friction of the extruded material against the rotating wheel generates a force that is pushing the material into the deformation chamber followed by extrusion through the die orifice. The extrusion by CRE was performed on an MC-260 device supplied by Meltech-Confex and installed at IMN - OML for processing of the 6063 aluminium alloy. The feedstock was composed of annealed rods. Two parameters were controlled during extrusion: the temperature of the shoe (element of the housing pressing the extruded material to the wheel) and the speed of the driving wheel. The 6063 alloy was extruded using the wheel speed of 2, 5, 10 and 15 rpm and the shoe temperature of 90°C and 105°C. The extruded flat sections were examined visually for continuity and quality of the resulting surface. In the feedstock rod and in the extruded flat sections (before and after heat treatment), the microstructure and grains were examined by light microscopy. Mechanical properties were also determined (static tensile test and hardness measurement). The study shows how the structure and the mechanical properties of the extruded flat sections are changing depending on the extrusion parameters applied. From the 6063 alloy rods extruded by CRE, flat sections of satisfactory quality were obtained. It was found that CRE yields the highest mechanical properties combined with the correct structure and high surface quality when the feedstock is extruded with the wheel rotational speed of 10 rpm and the shoe temperature of 105°C.

Development of a Force Parameter Model for a New Severe Plastic Deformation Technique – Multi-ECAP-Conform

Severe plastic deformation is one of promising techniques for omproving metal properties. In this work a new SPD technique – Multi-ECAP-Conform – is studied. The technique ensures an accumulation of a true strain degree to е>2.5 during one processing cycle. Models for force characteristics calculation have been developed on the basis of theoretical procedures of metal forming. The derived equations determine force parameters of the Multi-ECAP-Conform process.