Дослідження електричних показників і кінетики температури під час електроконтактної обробки напівфабрикатів

Abstract

Досліджено електричні показники та кінетику температури під час електроконтактної обробки напівфабрикатів. Установлено, що кінетика сили струм у під час електроконтактної теплової обробки зразків , однакових за об’ємом і різних за складом, не однакова. Швидкість нагрівання залежить від складу зразка та його об’єм у. Для інтенсифікації нагрівання необхідно регулювати електричні показники, тоді процес електроконтактного нагрівання м оже стати базовим для розробки ком бінованих способів теплової обробки.

Analysis of the processes of heat treatment of semi-finished products has found that the main drawbacks of processes and apparatuses are significant duration and unevenness of the temperature field by volume of the product, highenergy intensity and labor intensity, low efficiency, significant loss of mass and nutrients. In this regard, the idea of combining superficial heating methods with electrical contact heating (ECH), which would intensify the process and provide even heating of certain layers by volume of the product, was proposed. The main precondition for this is the purposeful regulation of heating of the central layers of the semi-finished product by means of ECH, which will enable the internal volume to be warmed up to the cooking temperature during the time which does not exceed duration of the crust formation on the surface. In such case, an important factor is the influence of electrical parameters (current, voltage, energy consumption) on the heating process and influence of the component composition of semi-finished products on the temperature kinetics. Substantiation of the use of ECH and its features is as follows. Thus, in the case of contact with electric current, electric energy is converted into heat directly in the semi-finished product, which allows to use it effectively primarily for thermal processes. At the same time, ECH does not allow to heat the surface of the product above 100°C and, accordingly, it is impossible to obtain a roasted crust only at the expense of ECH. Consequently, manufacture of products with the use of ECH can be effective, but it requires combined treatment with application of IR heating, for example. The aim of the research is to determine electrical parameters and temperature kinetics in the electrical contact processing of semi-finished products. Electrical parameters and temperature kinetics during electrical contact processing of semi-finished products are investigated. It was found that kinetics of current strength during electrical contact heat treatment of samples with the same volume but with different composition is not the same. The speed of heating depends on the composition of the sample and its volume. To intensify heating, it is necessary to regulate electrical parameters, and then the ECH process can become the basis for the development of the combined methods of heat treatment.