Моделирование теплопроводности порошковой среды применительно к задаче селективного лазерного плавления

Abstract

The speed and the cost of implementation of new techniques are directly dependent on the efficiency of each of the technological chain at all stages, from design and product design to create of its original mockup in full value. Dramatically accelerate the passage of these steps help to high-tech methods of 3-D computer modeling and the creation of hard copies of machine parts. Currently all over the world carry out intensive scientific research and experimental structure work not only on the creation of new, but also on the improvement technology previously deve­loped of methods and layered systems of laser synthesis of volume products (LSOI) machine parts. Methods of selective laser sintering(SLS), melting (SLM) and a three-dimensional laser melting (the DMD) is one of the most promising ways to implement rapid prototyping techno­logy[1]. There fore, the study of this topic at this point is urgent. Currently in many industries, are large heat flows from one surface to another, whereby even slight contact resistance causes local overheating, which is often highly undesirable. In this work was to study the effectiveness the thermal conductivity of granular systems, which was seen as a function of porosity, thermal conductivity, filling the pores of the material, the thermal conductivity of the gas microgap, the thermal conductivity of the particles themselves and contact the thermal conductivity at the junction of the particles. For theoretical studies of selective laser sintering it is necessary to develop methods to describe the effective thermal conductivity (EKT) powder medium, which take into account, that heating the partial or complete melting of the material areas may occur, resulting in a change in the structure of the medium. This implies an important requirement for EKT model: structural model in the limit of the total melting particulate material should give a value of the effective thermal conductivity, which is cross-linked with an effective thermal conductivity given by non-structured model. For the case of complete melting particles melt method is proposed for calculating the effective thermal conductivity gas as described in work.