Applied Mechanics and Materials Vol. 657

Abstract: The turning followed by burnishing is used like a combined process by using a combined tool having incorporated a turning tool and a burnishing system. This process is applied after different machining operations in a single hybrid process and can lead to the following advantages: the improvement of the part surfaces quality and to an important reduction of the costs and manufacturing times. The part surfaces quality obtained by applying the above mentioned process is influenced by a lot of factors, the most important among these being the working parameters. In the present paper there are presented the results concerning the determination of the optimal working parameters in order to obtain a high quality of the machined surfaces by applying the Response Surfaces method. The obtained results were verified by experimental tests and confirmed the efficacy of the method applied to optimize the results of the burnishing-turning combined process.

Abstract: The cutting followed by burnishing, used like a combined process, leads to the improvement of the part surface quality (roughness, hardness, microstructure etc.) and to reduction of the costs and manufacturing times as a function of different working parameters. One of the factors and parameters that characterize the machined surface by this combined process is the residual stresses that are generated and located in the part deformed strata. The present paper analyses the results concerning the experimental determination of the residual stresses generated in the machined surfaces of parts made from magnesium alloy by the burnishing - turning combined process. The experimental investigations have shown that in the machined strata the combined process determines the occurrence of the compressive residual stresses and hence the fatigue and cracking resistances of the machined materials will be improved.

Abstract: The evolution of modern industrial society is based on the conceiving of new, high-performance machine-tools, with an emphasis on cold forming ones. Identifying new constructive and/or kinematic solutions is one of the modalities ensuring the desired progress.Machine-tool kinematics is a field allowing for the synthesized representation of the often complex structures of existing machines, thus facilitating their study upon removal of less non-essential details [, as well as for conceiving new machines starting from imposed requirements reflected in adequate kinematic structures together with their necessary logical links.Cold-forming machine-tools are a most widespread and useful category, particularly for series and mass production. Their kinematic structure is typically simple. The specific kinematics of new types of cold-forming machines, many specialised or special, is rarely addressed.A particular class of cold-forming machine-tools includes presses with several main effectors elements. In addition to the well-known double or triple action mechanical presses, quite characteristic for this category are certain automatic mechanical presses. The paper addresses the kinematics of hypocycloid automatic presses [2,, a sub-class of machine-tools developed innovatively over the last two decades following research conducted a Transilvania University of Braşov, Romania.

Abstract: This paper presents the results of some research with different heat treatments for the steel OSC10 compared to steel 205Cr115 of which have made the cut punches, each one realizing 16,000 stampings in the same technology. A study was done on the wear of used tools stamping operations using the method of deviation from circularity. Due to the fact that the material of workpiece sheet has fibers orientated in the direction of lamination the cutting tools encounters resistance in a different manner on their circumference. In some portions the edges penetrate perpendicularly to the fiber, the cutting material poses a higher resistance and obtains more pronounced wear of the edges. On the other portions, the edges penetrate parallel with the fiber, in this case the material strength is low and provides a wear less pronounced.

Abstract: This paper presents a design methodology of laminating tools for automotive interior parts using CATIA software package. The authors developed a software tool named LTFrameDesign using VBA for Application under CATIA package, which automatically generates the main frame of the laminating tool according to the parts shapes, its dimensions and designer requirements. The software automates some stages of standard design and minimizes the design time and costs. The paper also presents the design stages which are followed by the user to obtain a 3D complete assembly of the laminating tool.

Abstract: In our present days numerical simulation became an important tool of engineering. Numerical simulation methods allow quantitative examination of the complex processes and phenomena in the general area of physics and also provide an insight in their dynamic evolution and even can become important tools for the discovery of new phenomena. In essence, the numerical simulation transfer important aspect of physical reality in discrete forms of mathematical description recreates and solves the problems on computer and finally, highlights issues that the analyst required. This modern numerical method approach, attacks the original problems in all their details on a much larger platform with a much smaller number of assumptions and approximations, in comparison to traditional methods. Transposition of the physics problems in the virtual space, governed by the force of computers, numerical simulation - as scientific approach - is becoming increasingly interesting for many fields of research. Basically, by means of numerical simulation are addressed fields such as mechanics deformable solids, fluid mechanics, aerodynamics, biomechanics, astrophysics. Numerical simulations follow a similar procedure to all the scientific approach, which consists in going through several stages, as follows: the phenomenon, the physical model, mathematical model, discrete model, and coding, numerical solution. In the plastic deformation of metals are involved, besides the mechanical properties and some thermal properties because even if the process is applied in the initial state to a cold material, along the process changes occur because of friction between materials and tools and transformation of plastic mechanical work into heat. Basic mechanical properties of the materials are underline through characteristic diagrams of materials obtained in simple tests of traction and compression. These tests were carried out in the Polytechnic University of Bucharest, Romanian Research & Development Institute for Gas Turbines COMOTI, Institute for Calculating and Testing Aero-Astronautic Structures STRAERO, SC UPS PILOT ARM Ltd, and Asachi Technical University of Iasi. To achieve the major objectives of the numerical simulation of the technological process of cold plastic deformation, are incorporated into the physical model three types of surfaces: cylindrical, conical and profiled. The sizes of the initial geometry were established in accordance with the basic dimensions of processed products by this method. For delimiting surfaces to be machined, the addition of grip (the tail) has a reduced diameter. Geometric models provide strength and rigidity needed for safely and accurately processing technology of cold plastic deformation. Geometric models and specimens which had been subjected to tensile tests, compression and hardness were made in the Glass Factory, Chisinau, Moldova.

Abstract: Micro and mini manufacturing is becoming more important than before. Among micro and mini manufacturing processes, micro forming has economical and ecological benefits due to high production rate, low material scrap rate, net shape production, and improved mechanical properties through work hardening. Even though macro scale metal forming is well understood and has been extensively studied, these concepts cannot be applied directly to the micro scale metal forming [. In this paper, a conical mini-part was precisely evaluated from finite element (FE) simulation. The final geometry of the conical mini-part is affected by forming parameters of the deep drawing process (blankholder force, friction coefficient, speed of the deformation tools) and by the tool geometry. In order to reduce the geometry deviation, all the parameters must be studies separately to quantify their influence on the final mini-part geometry. This paper presents a study concerning the optimization of the forming process in order minimize the geometry deviation of the final parts. The main objective is to understand the factors that have the highest influence on the forming process of conical mini-parts and to modify them in such way that the resulted part is according to the designer specifications. The material used in this analysis is copper - zinc alloy with anisotropic properties. After the forming process of conical mini-parts is over and the part is removed from the forming tools, the geometry of the part is analysed and compared with the ideal shape. Due to cumulated effect of springback and other phenomena that affect the conical mini-part is not having the desired accuracy from the dimensional deviation point of view [2,. There are multiple factors that affect the mini-part geometry during forming process as: blankholder force, punch rounding radius, and side wall angle. The Dynaform 5.9.1 software was used to simulate the forming process. During optimisation process 27 simulations have been done. The part obtained after each simulation is analyzed and measured to quantify the deviation from the ideal part geometry. The presented optimization method is a good method to reduce the dimensional deviations. The advantages of this method are the reduced number of simulations tests that must be done and precision of the obtained results.

Abstract: This Paper Aims to Determine by Experiment Total Force and Stress of Deformation Depending on Punch Stroke and the Level of Deformation on Severe Plastic Deformation of Aluminum by Multiaxial Cold Forging. the Deformation Force in Multiaxial Forging Depends on a Number of Parameters of whom the most Important are: Strain, the Flow Force of Aluminum, Deformation Speed, the Friction between the Material and the Die, Shape and Size of Die, the Dimensions of Deform Profile, Shape and Dimensions of Workpiece, Temperature Variation during the Process, Physical and Mechanical Properties of the Workpiece Material, the Structural Inhomogeneity of Workpiece Material. the Deformation Process is Discontinuous and Includes Deformation Processes that Define a Cycle of Severe Plastic Deformation. this Paper Aims to Determine the Force and Stress Corresponding to the First 12 Cycles of Severe Plastic Deformation.

Abstract: Incremental forming is one of the manufacturing methods which uses relative simple technological equipment and can assure a high rate of the process flexibility. These requirements can assure the efficiency demanded by the industrial market, in the case of small production batches, which occur more and more often nowadays. To ensure the stability of the process, the required quality and dimensional accuracy of the parts have to be well controlled. This requires the evaluation of the parts dimensions by certain measurements. For hollow parts, the measurement of their thickness is always a challenge, mainly when the dimensions are smaller and their depth is greater. This paper presents a digital method for the parts dimensional evaluation and analysis, which can be very accurate and does not need mechanical contacts with the part during measurements. The parts were scanned with a 3D blue light scanner, on their both sides and then the data was processed into specialized software, to obtain the parts digital surface from the 3D scanned data. The digital data was compared with the theoretical approach, to establish some conclusions on the validity of the sinus law and to point out the critical zones, where the thinning is strong and may cause fractures. The digital scanning method presented can be used also for quality control and inspection, as the processing steps are considered user-friendly and easy to adapt to certain specific requirements.

Abstract: On the properties of exploitation of the parts, a major influence has the quality parameters of working surface. Under the term "quality superficial layer" it is understood the integrity of such indices as: geometric precision, undulation, form precision, work surface microgeometry, physical and mechanical properties of the superficial layer. In most cases, the influence of these indicators on the exploitation characteristics of the surfaces are examined separately, but of their reciprocal interaction is evident. Roughness and precision machining of the surfaces have a significant influence on the characteristics of the machine. In most cases, the roughness and precision machining is indicated depending on the operating conditions of the surface. Varying with processing parameters, we can manage forming the surface roughness and surfaces precision. In this paper will present how influencing processing parameters on surface roughness and precision surface.