RU2438272C1 - Induction hot air furnace - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: induction hot air furnace is made in form of "¿"-shape magnetic conductor and has horizontal closed channel for metal melting in form of torus of elliptic cross section. Primary winding is made on a middle core of the "¿"-shape magnetic conductor; the secondary winding consists of two parts positioned over the first winding so, that its one part is over a horizontal channel with melt of metal, while another one is under the channel. ^ EFFECT: raised efficiency of melt mixing in furnace and its raised output due to elimination of oxides build-up in channel part. ^ 4 dwg

Description

Known detachable induction unit of a channel furnace (ed. St. No. 1300284, F27D 11/06, published 03/30/1987. Bull. No. 12), containing a magnetic circuit, the main coil and an additional coil connected to an external voltage source.

However, the known device does not allow to obtain the same rotation of the melt in the entire channel part of the furnace, since the channel part consists of longitudinal and transverse channels.

Known induction furnace channel type (patent No. 2120202, H05B 6/20, F27D 11/06, published 10.10.1998), containing a transformer with primary and secondary windings formed by a bath for molten metal and a horizontal closed channel.

The disadvantages of the known furnace should be attributed to the fact that it does not allow intensive mixing of the melt from the equilibrium components, in addition, the channel part of such a furnace is overgrown with oxides during operation and requires periodic cleaning.

The basis of the invention is the task of increasing the efficiency of mixing the melt in the furnace and its productivity by eliminating the overgrowth of the channel part with oxides.

The problem is solved in that in an induction channel furnace made in the shape of a transformer with primary and secondary windings and a horizontal closed channel, according to the invention, the primary winding is primary and located on the central core, and the secondary winding consists of two parts placed on top the main winding in such a way that one part is located above the horizontal closed channel and the other below it, while the horizontal closed channel has the shape of a torus with an elliptical cross-section Niemi.

Figure 1 shows a sketch of an induction channel furnace, figure 2 is a section BB in figure 1, figure 3 is a section GG in figure 2; figure 4 is a section aa in figure 1.

The induction channel furnace has a Sh-shaped magnetic circuit 1, the main winding 2 is placed on the central core of the magnetic circuit 2. A two-part secondary winding 3 is located on top of the main winding so that one part is above and the other under a horizontal closed channel 4. Internal surface horizontal closed channel 4 is made of a lining material and has a shape of 5 in the form of a torus of elliptical section. The horizontal closed channel 4 has devices for a bay 6 and a drain 7 of molten metal.

Induction channel furnace operates as follows.

, который создает переменный магнитный поток

Часть этого переменного магнитного потока

замыкается по магнитопроводу и индуцирует в канале 4 с расплавом электрический ток

. Другая часть магнитного потока

представляет собой магнитный поток рассеяния

пронизывающий канал 4 в вертикальной плоскости.When the main coil 2 is connected to an AC voltage source, an alternating electric current arises in it

which creates a variable magnetic flux

Part of this variable magnetic flux

closes by magnetic circuit and induces an electric current in channel 4 with a melt

. Another part of the magnetic flux

represents magnetic flux scattering

piercing channel 4 in a vertical plane.

As is known, in the short circuit mode (the secondary winding is shorted), the transformer has large scattering magnetic fields, which are mainly concentrated between the primary and secondary windings outside the magnetic circuit.

, который пронизывает канал с расплавом в горизонтальной плоскости. В результате наложения магнитных полей

и

, которые сдвинуты относительно друг друга по фазе и в пространстве, создается вращающееся магнитное поле. Величина вращающего момента, а следовательно, и скорость расплавленного металла зависят от величины тока во вторичной обмотке 3 и его фазового сдвига по отношению к току

основной обмотки 2. Поскольку канальная часть в виде тора с расплавом расположена симметрично относительно центрального сердечника магнитопровода 1, в любом его сечении возникает одинаковый вращающий момент, создающий вращательное движение расплава с угловой скоростью Ω.When connecting the secondary winding 3 to an external voltage source, an electric current is generated in each of its parts, creating a magnetic flux

which penetrates the channel with the melt in the horizontal plane. As a result of superposition of magnetic fields

and

which are shifted relative to each other in phase and in space, a rotating magnetic field is created. The magnitude of the torque, and therefore the speed of the molten metal, depends on the magnitude of the current in the secondary winding 3 and its phase shift with respect to the current

main winding 2. Since the channel part in the form of a torus with a melt is located symmetrically with respect to the central core of the magnetic core 1, the same torque arises in any of its cross sections, creating a rotational motion of the melt with an angular velocity Ω.

It should be noted that in such a “toroidal vortex” a ring movement around its axis spontaneously occurs with a linear velocity V. This is because at each point on a segment connecting diametrically opposite points of the perimeter, the values of the linear velocity of the melt are different, and, accordingly, the melt speed during the transition along the inner wall of the channel from a small perimeter to a larger perimeter will be extinguished or change its direction.

As a result of the addition of rotational and circular motions, the melt in the toroidal channel moves along a helical path, because The rotational motion of the melt with an angular velocity Ω also implies its motion along the axis of the torus with a velocity V. As a result of the experiments, it turned out that the shape of the ellipse is optimal for the channel cross section, allowing it to fill the magnetic circuit window most completely. The shape of the window of the U-shaped magnetic circuit and the location of one part of the secondary winding above the channel and the other part of the secondary winding under the channel make it possible to achieve the greatest efficiency in terms of fill factor and power factor cos φ in the case of a rectangular channel shape. The rectangular shape of the channel during the movement of the melt in the corners has stagnant zones in which the channel will overgrow in the first place. A channel having an elliptical cross-section allows increasing the cos φ of the induction channel furnace due to the fact that the fill factor of the magnetic circuit window is increased and, accordingly, the magnetic flux penetrating the melt increases. The elliptical shape of the channel cross section allows to reduce the overgrowth of the furnace channel and increase the efficiency of the furnace.

Claims (1)

An induction channel furnace made in the shape of a transformer with a primary and secondary windings and a horizontal closed channel, characterized in that the primary winding is the main one and is located on the central core, and the secondary winding consists of two parts placed on top of the main winding in this way that one part of it is located above the horizontal closed channel and the other below it, while the horizontal closed channel has the shape of a torus with an elliptical cross-section.

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