Simulation and Test of the Spinning Process Applied to Platinum Metals
Solid materials must necessarily be given a specified shape in order to be used in technical applications. A major part of engineering science and technology is related to the different shaping techniques. The most important criteria for the choice of the
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9.1 Necessity to Shape Materials Solid materials must necessarily be given a specified shape in order to be used in technical applications. A major part of engineering science and technology is related to the different shaping techniques. The most important criteria for the choice of the respective technique are the necessary precision, expenditure and waste, or economical aspects for short. Many different shaping techniques are described in [9.1-4] with emphasis on metals because of their widespread use; for the shaping of non-metallic materials the reader is referred to special literature, such as [9.5] for glasses. Roughly, one discriminates between the shaping in the viscous and in the solid state of materials. As a consequence, one needs to know the viscositystrain and viscosity-temperature curves in the first case, and the stress-strain curves in the second. Characteristic of the viscous state is the possibility of deformation and shaping even under low forces or stresses, whereas in the solid state deformation is achieved essentially by stresses exceeding the yield stress. Thus, there is no linear relation between the deformation and the applied stresses in the solid state, which renders the description of deformation of metallic solids more difficult. In this chapter, a special technique, the spinning of metals of the platinum group, will be considered. Such metals are widely used in the glass industry. The spinning process is quite economical to produce pieces with rotational symmetry. However, it requires some experience and sometimes several trials, which might increase production costs and cause waste of material. Because the production costs of metals of the platinum group are high, one is interested in avoiding unsuccessful trials. Therefore, a simulation strategy has been developed and practically verified to reliably calculate successful spinning curves and to avoid failures, which will be described in the subsequent sections. It will be demonstrated by the shaping of crucibles starting from sheets of Pt metals.
9.2 Qualitative Description of the Spinning Process The metal-forming process "spinning" is applied to thin circular sheets of metals to produce, by a continuous bending and pressing process on a spinH. Loch et al. (eds.), Mathematical Simulation in Glass Technology © Springer-Verlag Berlin Heidelberg 2002
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9. Spinning Process Applied to Platinum Metals
ning lathe, hollow pieces with a rich variety of shapes with rotational symmetry (see Fig. 9.1). A circular blank of sheet metal (1) is clamped by a pressing device (9) to a rotating spinning chuck (3), which is mounted to a spindle (7). The blank rotates with the spindle (7) and the pressing device (4), which is supported by the tailstock (9), while a spinning roller (2) mounted on an x-z support (8) is pressed to it and shifted back and forth along spinning curves (usually in a plane passing through the axis of rotation), until its flange (10) fits the spinning chuck (3). A series of possible spinning curves are also shown in Fig. 9
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