Istraživanje temperaturskog polja u reznom alatu pri obradi na strugu na suvo sa hlađenjem reznog alata sistemom na bazi termoelektričnog modula
Research of the temperature field in cutting tools when dry cutting on a lathe with a thermoelectric module cooling system
Nikolić, Radovan H.
Faculty:Универзитет у Нишу, Машински факултет
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The subject of research of this doctoral dissertation is to explore the possibilities of the implementation of systems based on a thermoelectric module (TEM) for cooling the cutting tool. This cooling becomes significant when it is not possible to use conventional coolants and lubricants (CLM). Starting from existing mathematical models for the calculation of the temperature field of the cutting tool, a mathematical model is developed that takes into account the cooling based on the TEM. The use of the finite element method (FEM) determine temperature field when finishing grinding dry in the cooling conditions based on the TEM. The Software package, PAK-T, is used for the calculations and was developed at the Department of Applied Mechanics, Faculty of Engineering Sciences in Kragujevac. The system for cooling the cutting tool based on the TEM was realized under laboratory conditions on a prototype model, which consists of a cutting tool and a thermoelectric module. Verification of the
obtained results was carried out on the basis of a mathematical model by experimental research of the temperature field of the cutting tool in terms of cooling based on a TEM. The dissertation text is composed of eight chapters. The first gives an overview of previous research in the area of monitoring and modeling of temperature fields in the cutting process. As the focus of this dissertation is the cooling of the cutting tool based on a TEM in dry processing, the overview of research in this field is provided in this chapter. The subsequent section presents the theoretical considerations of the cutting process, which are related to temperature occurrences in the cutting zone. Starting from the basic models of chip formation, the basic parameters of the geometry and mechanics of cutting are defined as are their relationships and calculations. Determination of the characteristic parameters is also shown as they are required for the calculation of the power of the heat sources. In the third chapter, with previous theoretical considerations in mind, the heat sources and sinks in the machining system of cutting are analyzed. Starting from existing models, accounting for new knowledge with respect to the convection and conduction of heat, and bearing in mind the limitations and capabilities of the existing software, a mathematical model is developed for calculating the temperature field of the cutting tool when dry processed without cooling. This model is the basis for further upgrades and calculations of temperature fields in conditions of cooling of the cutting tool based on TEM in processing of dry scraping. The fourth chapter gives the basics of cooling based on the ТЕМ. Starting from the essence of thermoelectric occurrences, the thermoelectric processes are explained. Considering the basic thermocouple, the basic equations for calculating are derived. The thermoelectric module is defined, and the equations derived for thermocouple are applied to the ТЕМ. Through detailed analysis of the work of the TEM, the heat flux is defined as that which draws module from the object being cooling. This equation is the boundary condition in the mathematical model. Starting from the basic model, the fifth chapter develops a mathematical model for the calculation of the temperature field of the cutting tool in processing by dry grinding with cooling using a ТЕМ. The base model is revised by taking into account modern knowledge about convection and heat conductivity and by adding a boundary condition representing a heat sink at the place of the ТЕМ. Тhe sixth, seventh and eighth chapter provides an overview of the results obtained, a description of the experimental equipment used for measuring the value of the temperature field, the arrangement of measuring points on the cutting tool, and other conditions for conducting an experiment. Described in detail is the construction of a prototype model of the cooling system of the cutting tool based on a thermoelectric module (TEM) as are other conditions for conducting an experiment. Finally, a comparative analysis is carried out; a detailed overview of the results obtained from the mathematical model and experimental data from the prototype is performed. The scientific contributes of the doctoral dissertation are as follows: Development of new systems for cooling the cutting tool in conditions when it is not possible to use conventional CLM, Development of a mathematical model for the calculation of the temperature field of a cutting tool cooled by a system based on a TEM, Mathematical model that can be applied for the calculation of temperature fields in other cases when cooling systems of other objects are based on a TEM, for the known intensity of heat sources, Possibility of analyzing the impact of different modes of cooling on the temperature of the cutting tool, Selection of an optimal cooling mode for given workpiece materials and cutting tools, applied processing conditions, and method of calculating temperatures of each of the applied modes, By cooling in this manner, the thermal effects on the cutting tool when processing dry are avoided and lessened are their impact on the intensification of wear, thermal deformation and accuracy, It furthers current research in the field of thermoelectricity as well as possibilities of its application in this field, Encourages further work on research, development and application of the cooling system based on TEM in the field of cutting tools.View More
Keywords:Temperatursko polje, rezni alat, toplotni izvori, toplotni ponori, termodinamika rezanja, elektrotermija, obrada na suvo, hlađenje, termoelektrični modul (TEM), metod konačnih elemenata (MKE), postojanost alata; dry processing, cutting tool, heat sources, heat sinks, temperature field, cooling, thermoelectric module (TEM), finite element method (FEM), cutting tool lifetime