Vasyliev Yurii

Abstract

Content

• Introduction
• The model of the mold
• The result of the experiment
• Literature

Introduction

Modern pereplavnye processes produce high quality ingots for aviaraketostroeniya, energy and other technology industries carry metal melting in water-cooled copper mold. Such processes include electroslag (ESR), vakuumnodugovoy, electron beam, plasma and other remelting. The quality of the ingot in such processes, is largely determined by the shape and size of the liquid metal bath, so the control of these parameters in actual refining process. At the moment, there are many universal software for the simulation of physical processes including crystallization ingot, which allow you to specify the conditions of heat and crystallization, and to evaluate the shape and size of the metal bath. Many research teams developed their own thermal model pereplavnyh processes. The advantages of mathematical modeling are undeniable, but to obtain a reliable result it is necessary to have accurate values ??of heat transfer boundary conditions. As such, in this paper, it is proposed to use the mold wall temperature by cooling water, which is offered to fix it for a certain amount of height thermocouples at equal distance between them. To reduce labor intensity and increase the visibility of research, testing of thermocouple attachment technology on the surface of the mold wall decided to hold the first on a physical model of the ESR. As a consumable electrode in it will act as an electrode diameter of 20 mm of Wood's alloy, having a melting point of about 80 ° C. As the slag bath will act hydrochloric acid solution, the heating which would occur under the action of flowing an electric current through it. The task to be solved at the first stage of the study, is a refinement of an existing physical model ESR, which has a number of shortcomings and is not suitable to solve temperature measurement problems. Thus, in the existing model ESR melting of the alloy electrode made of Wood's glass vessel diameter, which substantially exceeds the diameter of the consumable electrode that does not correspond to the actual values ??of the coefficient of filling of the mold. A major shortcoming of the existing model is a weak heat from the "slag bath", in which it has a significant thermal inertia. To approximate the cooling conditions of the slag bath and the ingot to the real, it is necessary to organize its water cooling.

The model of the mold


Figure 1 - Experimental crystallizer

To check the possibility of overheating of the electrolyte bath in a cooling water gathered its simple design, consisting of a glass bulb of 20 mm diameter, and a plastic bottle of 0,5 liter (Fig 1). Glass bulb acts as the mold and the sleeve made therein Wood melting alloy in the electrolyte. It is pressed sealingly into a plastic bottle, which has connections for the supply and removal of cooling water flask. At the bottom of the flask is placed a metal washer with a diameter slightly smaller than the diameter of the flask, to which through an insulated wire is connected one terminal of the power source. The second terminal is connected to the electrode remelted alloy Wood. The melting of the electrode was carried out on laboratory ESR installation, which has a mechanism for securing and moving the electrode, power supply devices for the control of current and voltage remelting. Moving the electrode is carried out automatically by specifying the required speed and direction of movement. Voltage remelting can be smoothly set in the range of 0 to 25 V. The maximum current remelting is about 20 A. The height of the electrolyte in the flask was 3 cm. After penetration of the electrode into the electrolyte came his quick warm-up for 1-2 minutes, and began the process of melting. The thermal inertia of the electrolyte bath has decreased, which is what we wanted. However, the cooling water temperature is almost not changed because of the low thermal conductivity of the glass bulb. Thus, the results of practical experiments have shown that the heat released in the electrolyte (Fig 2) is sufficient to melt the alloy electrodes Wood flask under cooling with running water. Now, however, heating is required to check the electrolyte under conditions of heating are not in a glass flask, and with metal in the mold walls. Currently, work is underway to create a model of the mold, in which two opposite walls will be made of steel and are water-cooled, and the other two will be made of a thick-walled glass and will be in contact with air. For water-cooled metal walls of the mold are mounted thermocouple, and through the glass - be monitored for melting metal and crystallization process.

The result of the experiment


Figure 2 - The resulting cast



Literature

1. Multiphase modelling slag region in the ESR process / A. Kharicha, W. Schutzenhofer, A. Ludwig, R. Tanzer // International Symposium on Liquid Metal Processing and Casting, Nancy, – 2007. – P. 107-111.

2. Minisandram R., Arnold M., Williamson R. VAR pool depth measurement and simulation for a large diameter Ti-6Al-4V ingot // International Symposium on Liquid Metal Processing and Casting, Santa Fe, 2005, P. 1-6.

3. Hernandez-Morales B., Mitchell A. Review of mathematical models of fluid flow, heat transfer, and mass transfer in electroslag remelting process // Ironmaking and Steelmaking, 1999. – Vol. 26. – № 6. – P. 423-438.