SU985684A1 - Crucible for high-frequency induction melting of melts - Google Patents

Description

The invention relates to metallurgy and, in particular, to the structure of crucibles for high-frequency melting of metals.

A crucible is known for high-frequency induction melting of metals, consisting of cooled open sections, the inner walls of which are facing the melt; made of metal with an electrical conductivity of 4-6 x x10, Ohm / m. The outer walls of the section of such a crucible are made of non-conducting material tl.

However, this crucible is not sufficiently reliable due to the destruction of the outer walls of the sections.

The purpose of the invention is to improve the reliability of the crucible.

This goal is achieved by the fact that in a crucible for high-frequency induction melting of metals consisting of cooled open sections, the inner walls of which, facing the melt, are made of metal with electrical conductivity 4-6 and 10. Ohm / m, the outer walls of the sections are made of metal with an electrical conductivity of 1-3-10 Ohm / m.

The drawing shows the proposed crucible, a cross-section.

The crucible consists of open metal cooled sections 1 (circled in dotted lines) surrounding the melting space. The outer walls 2 of the section 1 are hermetically connected to the inner wall 3. The connector 4 of the outer wall 2 is filled with an electrically insulating material, for example, epoxy resin.

ten

During operation, the crucible for high-frequency induction melting of metals eliminates the induction of induced currents in the outer walls of sections with a thickness of up to 8 mm when melting at frequencies

15 4000-10000 Hz, since the wall, the thickness not exceeding two depths of penetration of the electromagnetic field into the metal of the wall, is transparent for such a field.

20

The penetration depth of the electromagnetic field at a frequency of 10,000 Hz into stainless steel is 2.8 mm, which allows external

25 wall section thickness of 5 mm and solve all the difficulties of design, ± technological and operational nature arising in the manufacture and use of cold crucibles.

. The selected boundary conductivity values are due to the following. The walls of the crucible section facing the melt should have a high electrical conductivity. The use of highly conductive metals. for the manufacture of sections, the crucible causes the induction of eddy currents in this crucible during the induction melting of metals, and, consequently, the electrical losses, which will be the smaller, the higher the electrical conductivity of the metal. Therefore, the electrical conductivity of the metal of the wall facing the melt should be 4-6 10 ohm / m. The highest electrical conductivity, about 610 ohm / m, is silver i and copper. The use of materials with a conductivity of less than 4-10 ohms per meter is no longer feasible due to an increase in electrical losses in the section, which leads to a decrease in electrical efficiency.

For the outer walls of the section, it is proposed to use metals having an electrical conductivity in the range of 1-3 Ω / m. This is because the outer wall must be transparent to the electromagnetic field and the lower the electrical conductivity, the greater the transparency of the Metal. In the open transparent section there are no electrical losses.

The lowest electrical conductivity at the operating temperature of the section has alloyed steel (3-10 Ohm / m). This is due to the choice of the boundary values of the electrical conductivity for the outer walls of the section. However, the use of mettschlov with a higher electrical conductivity (more WU Ohm / m) eliminates the possibility of technical implementation of the design of crucibles with low electrical losses.

Claims (1)

1. USSR Author's Certificate No. 881509, cl. F 27 D 11/06, 1980.