Applied Mechanics and Materials Vol. 657

Abstract: Metal spinning on NC machine-tools is a very flexible and complex manufacturing method which has a high efficiency for small series of parts and prototype parts. The algorithms used for calculating the roller trajectory during the metal spinning process are usually complicated and hard to apply into production. This article presents an original application developed using Visual LISP that can be used for calculating and then simulating and testing the roller trajectory in the case of manufacturing rotational complex parts by metal spinning. The simulation prevents any errors that can occur during the process of manufacturing before the parts are actually put into production.

Abstract: Mini forming is an appropriate technology to manufacture small metal parts, as these are required in many industrial products resulting from mini-technology. This paper work want to underline the fact that even in down scale there are problems regarding deviation from the required dimensions. One of the problems is scaling effects, which occur in tribological aspects such as the friction coefficient, which increases with decreasing specimen size. Simulations investigations into mini forming process were carried out and mini conical parts have been obtained with different geometries. . The main objective is to observe and quantify behaviour of the mini parts during forming process and geometry deviations that affect the final product. The material used in this analysis is copper - zinc alloy with anisotropic properties. During forming process of conical mini-parts, the material record important variation along the part length and generate important shape deviation. This phenomenon causes deviations of sidewall angle, superior diameter, inferior diameter, mini part height, and connection radius between the part bottom and sidewall. There are multiple factors that affect the geometry deviations: sidewall angle, friction coefficient, tools gap, punch radius, and punch speed. The Dynaform 5.9.1 software was used to simulate the forming process. The part obtained after each simulation was analyzed and measured to quantify the deviation from the desired geometry on the final conical mini-part. In the final part of this paper some conclusions regarding geometry deviation of conical mini-parts obtained by forming are presented.

Abstract: The Single Point Incremental Forming Process (SPIF) involves extensive plastic deformation. The description of the process is more complicated by highly nonlinear boundary conditions, namely contact and frictional effects have been accomplished. The SPIF analysis is mathematically complex. However, due to the complex nature of these models, numerical approaches dominated by the FEA are now in widespread use. The paper presents the data and main results of a study on SPIF through FEA, that permits the modeling of complex geometries, boundary conditions and material behavior. SPIF have been studied under certain process conditions referring to the test workpiece, tool, etc., using ANSYS 11.0. An important result is showing that the model of simulation can give as clearly the behavior of contact tool - workpiece and the effect it on strain and stress distributions, also on the accuracy of product. Relevant dependences between tool and workpiece surface interface and sample of results have been demonstrated.

Abstract: The The 3D modelling, compared to the 2D-symmetrical rotation (axial) modelling, is much more complex and one of the reasons for this, with a view to plastic anisotropy, is that 3D modelling adopts normal anisotropy while 2D modelling adopts symmetrical rotational anisotropy. When the finite element method is used for numerical solving, the number of nodes in the discretization network is much larger in the 3D modelling and even when using last generation PCs the processing time is much longer. For this reason, for expedite calculations, as those needed to establish, in a first approximation, the optimal parameters of a deep drawing process I analysed in this paper the possibility to use the 2D-symmetrical rotation (axial) modelling. In a first phase, we intend to create a representative set of deep drawing problems and then to solve them through numerical simulations using Ansys package, using both the 3D modelling, in cartesian coordinates, and the 2D-symmetrical rotation (axial) modelling, in cylindrical coordinates. Runnings shall be carried out for various refinement levels of discretization network in finite elements. The calculation times shall be compared for these two modellings and following the comparative analysis of the results we can deduce the errors entered in the 2D modelling. These errors shall be assessed by analysing and comparing the extreme unitary stresses as follows: normal stress by the Ox and Oy axes , in the 3D modelling, and in the 2D modelling by the Ox / Oy axis; shear stresses by the XZ and YZ planes, in the 3D modelling and in the 2D modelling by the XZ plane.

Abstract: In the last few decades, the concept of flexible manufacturing has started to gain more and more attention, as an adaptation of production methods to the increasingly varied demands by customers. Therefore, new procedures have been introduced as alternatives to the classical ones, a very promising one being incremental forming [. A possible application for this new procedure, targeted by the authors of this paper, is the manufacturing of custom-shaped prosthetic parts for use in various areas of human medicine. Such prostheses can have a functional role, when they target the replacing of a functional component of the human body, or an esthetic role, when they target the solving of problems related to the appearance of the human body. Among all titanium and its alloys, the mainly used materials in biomedical field are the commercially pure titanium (cp Ti, grade 2) and Ti6Al4V (grade 5) alloy [.

Abstract: Incremental forming is a process with a high degree of novelty, so this paper describes first of all a series of theoretical principles of the incremental forming process. A main objective of the paper was the usage, as blanks in incremental forming process of bimetallic sheets. So the experimental researches have targeted the realising of parts with different shapes made from such type of blank. In the experimental researches was chosen as technological equipment for incremental forming the numerical controlled milling centre. The paper also present the tools used in incremental forming in order to obtain a hemispherical parts.

Abstract: The quality of bearing cages is influenced by a variety of technological factors which depend on the material they are manufactured of, on the hydraulic press and on the punching-stamping die. The paper presents an optimized methodology introduced and developed for process quality analysis and monitoring activities involved in the stamping technology in order to manufacture roller bearing steel cages. The stamping technology presented in this case study is part of a larger industrial process of manufacturing steel window-type cages for spherical roller bearings with two rows of symmetrical rollers. This approach aims to improve a similar process quality analysis and monitoring activities which were previously developed on the basis of cause & effect analyses made upon the influence of qualitative and quantitative parameters involved in a quality and accurate stamping process.

Abstract: The formability of tailor welded blanks is significantly reduced compared with the homogeneous blanks. This phenomenon is caused by the fact that there is a severe change in the material property sideways the welding line. Within 2-3 mm, in case of laser welding maybe less, there is a gradient of mechanical characteristics of materials. The research work presented in this paper deals with numerical simulation regarding forming of a cylindrical shaped part made from tailored blanks (TWBs), having the welding line situated symmetrical with respect to the part geometry. Due to dissimilar parent materials of the TWBs, it is difficult to anticipate the maximal depth of the formed part. The presented research is trying to determine the maximal depth of the TWBs part based on the maximal depth of the parts obtained from each parent material partly. To simulate the forming process of the cylindrical part the academically version of the Dynaform 5.8.1 software have been used. The obtained results are presented in the final part of this paper work.

Abstract: This paper presents materialization through a device of severe plastic deformation process by multiaxial forging. In essence, by design, the device includes a board reinforced with fretting rings where the severe plastic deformation takes place and an assembly, punch-counterpunch that transmits the force from the source and performs multiaxial forging as a discontinuous process. The device has a high level of universality and has the following advantages: contains an extraction system of deformed blank from the active fretted broad; ensures workpiece centering into place of active plate, contains a system for measuring the strength of forging; can be used on any type of press.

Abstract: The behavior of chrome alloyed steel in various combinations of inorganic media has been studied. Steel samples were processed by electrochemical discharge grinding in nitrates (KNO₃, NaNO₃), chlorate solution (NaClO₃) and nitrates with various additives (KNO₃+Na₂CO₃, NaNO₃ +NaClO₃). In inorganic solutions, the presence of a great number of negative ions (NO₃^-, ClO₃^- HO^-) resulted by electrolytic dissociation of the salts, increases the metal oxidation as well as anodic dissolution. The rate of metal dissolution increased with the increasing NO₃^- ions that accelerate the anodic dissolution