Structural thermophysical analysis of metal-cutting machines

Abstract

The energy that is supplied to metalcutting machines but is not consumed in cutting is converted to heat and stored in the system components, with some release to the atmosphere. This changes the ini� tial heat content of the machine tool's structure, raises the temperature in its components, and results in ther� mal deformation. The action of thermal energy on each component of the machine tool will be different, since the thermal and thermoelastic processes are determined by a wide range of factors. The interaction of the thermal energy with the components of the machine tool will depend on factors such as the type of source, the heat transfer with the surroundings, the method of heat supply, the shape and size of each com� ponent, the material from which it is made, its spatial orientation, and its interactions with contacting ele� ments. The influence of each factor will be different in magnitude; whether it needs to be taken into account will depend on the goal of the calculation, the required accuracy, the methods adopted, and so on. Therefore, in considering thermal processes in metalcutting machines, we may identify the following basic tasks: (a) structural thermophysical analysis, in which attention is confined to the most significant relations of the structures within the machine tool and their most general thermal and thermoelastic charac� teristics; (b) structural thermophysical synthesis, in which the fundamental structure of the metalcutting machine is formulated on the basis of standard and relatively uniform thermally stressed components, according to specified compatibility rules; (c) para� metric thermophysical analysis, in which the influ� ence of the parameters and characteristics on the heat� ing and deformation of components in the machine tool's thermophysical structure is considered; (d) parametric thermophysical synthesis, in which specified thermal stability of the metalcutting machine is ensured. We assume here that the initial data (thermophysi� cal, thermomechanical, geometric) are known on the basis of standards, handbooks or other documents. In some cases, we use estimates that adequately reflect the thermal processes in thermophysical analysis or synthesis of metalcutting machines. Determination of the thermal stability of metal� cutting machines and structural and parametric ther� mophysical analysis or synthesis will require a clear idea of the heat sources that act on the machine tool and their distinctive features. Therefore, the thermal stability of the metalcutting machine may be regarded as the outcome of the transformation of energy sup� plied to its structure. In Fig. 1, we present a general� ized picture of the formation and analysis of the machine tool's thermal stability, in which the stages of energy transformation appear in the order in which they are considered. An analogous approach is used in