Materials Science Forum Vol. 818

Abstract: Lap joints are most used joints in automotive industry. These types of welds are usually created by spot welding, but new technologies who came to automotive industry considerably do weld process faster. Paper deals with laser welding parameters and their influence of weld seams. The parameters of welding are readjusting according to shape of weld, impurities of surface and gap. Steel S500MC with thickness of 1.0 and 2.2 mm was used as the base material. For welding was used fiber laser Ytterbium Laser System YLS with power of 6000 watt from IPG Company. Research was oriented on changing weld parameters and their influence of welds quality. It was found that butt welding joints are sensitive to gap and the gap tolerances which in turn is dependent on material thickness, beam diameter, welding speed and beam quality.

Abstract: Fine blanking is a widely used process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Many studies on the weight reduction of automobile for fuel saving were underway. The clearance of the punch-die of a fine blanking tool is an important design factor that affects the sheared surface of a product. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. The main objective of this paper is to provide an overview of the effect of clearance between punch and die in a fine blanking tool on quality of sheared surface. A well as to specify the effect of mechanical properties of sheared steel sheet on blanked edge quality given by ratio of h_v/a_0.

Abstract: Forming dies are often costly for producers and the cost amount is influenced by production process too. If the die is manufactured by machining, proper strategies would necessary to consider as well. The right selection of adequate strategy helps production times shortening, tool wear reducing and those affect production effectiveness. Used strategies and its parameters are often compromise between acceptable surface quality and variations in shape aside, and production time on the other side. The paper presents the way of evaluation of milling strategy based on selected elements of forming die. This allows choosing the adequate strategy for particular shapes of die and also to evaluate them by the reached surface quality. Presented approach is verified by machining forging die cavity for production of connecting rod.

Abstract: The contribution deals with possibilities of new progressive technologies in materials joining processes. By using of friction, physical factors as temperature and thermal conductivity in joining, we can increase the quality of material joining and can join of various types of material. There is also shortage the production time, provide automation in operations is possible, spare of economical expenses and also we can protect the environment. The product increasing of automobile industry, pipe industry, development of mechanical products, materials, design of joining in civil engineering force the producers to accelerate the production and to utilize new technologies.

Abstract: This article deals with optimization and typing of the frames of the assembly presses which are used for assembly process of rolling bearings. The article describes the solution of technical problem from conception phase of the press frame to the phase of final CAD model design. Final solution contains of proposal for typing of dimensional series with five different sizes for five different press forces. The optimization of the shape and the dimensions, as well as typing, reduces manufacturing cost of the assembly presses. The build dimensions are reduced as well, while required stiffness and strength are preserved.

Abstract: Rapid prototyping (RP) is a modern technology which can produce components with very complicated shapes using different materials. This method also allows the production of components with shapes and geometry that would be very difficult to produce using conventional methods such as milling, welding and so on. A 3D printer builds an object from bottom to top, layer by layer. The purpose of this article is to introduce rapid prototyping technology for printing metal products. It focuses on various areas of application, advantages and disadvantages of this manufacturing technology as well as introduction of two methods DMLS (Direct Metal Laser Sintering) and LENS (Laser Engineered Net Shaping).

Abstract: This article deals with special kind of machining of multi-layer laminar composites called sandwich composites. This material consists of two outer layers that overlap core material at the centre made from a light material. This material is used in the automotive industry in interior parts such as dashboards, decorative parts and panels. The product is folded from thin plastic and aluminum. As customers require high-end quality for higher class-vehicles, machining must be ensured at as high a level as possible to suit customer demands. Appropriate processing methods have been investigated experimentally in order to choose the best tool that would guarantee a consistently high quality of cut depending on high durability. Therefore it is still necessary to permanently test new tools with different types of coating, including thin films and different geometry to achieve the required quality at less clamping milling tools, which need to be changed after some pieces and edge sharpen.

Abstract: The effect of microstructure on the mechanical properties of cord steel wires was investigated. Material properties and damage behaviours were identified. Metal cord, for reinforcing articles of an elastomeric material, such as tires, conveyor belts and so on of the single strand type, in particular made up of a plurality of 3, 4 or 6 wires, where in the said wires are twisted together loosely. The metal cord characterized by the fact that the diameter of the individual constituent wires varies between 0.12 and 0.30 mm. R_m tested cord wire was max. 2 946 MPa. Fracture surfaces cords steels were observed.

Abstract: The current trend particularly in industrial and commercial sectors is to search for alternatives to the current structural materials made from new lightweight materials. One option is to use unconventional material composite structures which have a combined fibre/matrix. Analysis of UD prepregs with unidirectional carbon fibres was performed. These special unconventional materials can be used for both flat and shaped structural products. The extent and quality of the saturation of the fibre layers in the resulting composite are important features for the whole complex of its parameters and influence its quality and mechanical properties. The experimental study also included an exploration of the inner structure and interactions of the individual components and detection of internal defects in the carbon UD prepreg composite using an X-ray microtomograph. The results illustrated the detection of microcracks, which significantly influence the resulting synergy of the composite and which were previously undetected.

Abstract: The development of nanoparticle reinforced polymer composites is presently seen as one of the most promising approaches in the field of future engineering applications. The unique properties of at least some of these nanoparticles (e.g., CNTs or carbon black) and the possibility of combining them with conventional reinforcements (e.g., carbon-, glass-or aramid-fibers) has led to an intense research in the field of nanocomposites. This study presents mechanical properties of two carbon composites made from bisphenol A epoxy resin (E) and 3 layers of 160 g/m² carbon cloth with twill (TC) and plain (PC) weave as a reference and three-composite system that consists from carbon fiber reinforced epoxy matrix and 1% of multi-wall carbon nanotubes dispersed in epoxy resin. Used hardener H507 was based on cycloaliphatic polyamine with absence of nonylphenol. Samples were also tempered at 80 oC (for 12hours) for improvement of their thermal resistance.