JPS6023095Y2 - melting furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a melting furnace such as a melting furnace or a holding furnace used for die casting of low melting point metals such as aluminum and bad lead.

Melting furnaces, which are generally used for die-casting of low-melting point metals, have a crucible with a higher melting point than the metal to be melted embedded in a heat-resistant furnace body.

A so-called crucible furnace is used. In most conventional crucible furnaces, the outer bottom surface of the crucible is heated by an internal combustion burner, and the crucible wall is heated to melt or maintain the metal in the crucible.

However, such an in-furnace combustion type crucible furnace has a thermal efficiency of about 20 to 30%, resulting in a large loss of thermal energy.

Alternatively, a method in which a tube burner is immersed in the molten metal in the crucible, and the high temperature gas burned by the burner is introduced into the tube in the crucible and the molten metal is heated by this tube.
In other words, the immersion tube burner type is also used, but even this immersion tube burner type has a thermal efficiency of 3.
It is about 5 to 45%, and more than half of the thermal energy is wasted as exhaust gas.

However, in recent years, as social demands for measures to save energy have been strongly desired, improvements in the thermal efficiency of the crucible furnaces have been required.

The present invention was developed based on these circumstances, and its purpose is to improve thermal efficiency by effectively utilizing the thermal energy in the exhaust gas discharged from the immersion tube burner, and to create a melting system that contributes to energy savings. The idea is to provide a furnace.

In other words, the present invention auxiliary heats the crucible wall by passing the exhaust gas from the immersion tube burner through the heating space formed between the furnace body and the crucible, and uses the thermal energy in the exhaust gas that would otherwise be wasted to heat the molten metal. The aim is to use this technology to improve thermal efficiency.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The figure shows a holding furnace for zinc die casting, and 1 is the furnace body.

The furnace body 1 is made of a heat-resistant, heat-insulating material such as ceramic, and is attached to a base 2 also made of ceramic or the like.

3 is a furnace body frame that covers the outer surfaces of the furnace body 1 and the base 2.

A crucible 4 is embedded and installed in the furnace body 1.

The crucible 4 is made of a metal having a higher melting point than zinc, such as cast iron.

A tube burner 5 is immersed in the crucible 4.

The tube burner 5 is connected to a burner 7 at one end of the immersion tube 6, and the burner 7 heats the supercharged air and pumps the heated air into the immersion tube 6.

The immersion tube 6 is bent and piped inside the crucible 4 with a slight gap between it and the inner wall surface of the crucible 4, and an exhaust gas conduit 8 is connected to the other end.

As shown in cross section in FIG. 3, the exhaust gas conduit 8 is formed into a U-shape, for example, by providing an outer tube 9 made of a thin-walled steel pipe or the like with a lining 10 made of highly heat-insulating fiber or the like.

An exhaust gas passage 11 connected to the exhaust gas conduit 8 is formed within the furnace body 1 .

A heating space 12 is formed between the furnace body 1 and the outer wall surface of the crucible 4, and the exhaust gas passage 11 communicates with this heating space 12.

Further, the heating space 12 is opened on the upper surface of the furnace body 1 and
and the crucible 4 are connected to exhaust holes 13 provided at a plurality of locations along the circumferential direction.

In a holding furnace with such a configuration, that is, a crucible furnace, the high-temperature gas burned and heated by the burner 7 passes through the wall of the immersion tube 6 during the process of being pumped through the immersion tube 6 and absorbs the molten metal in the crucible 4. Heat.

This performs primary heating (main heating) to melt the molten metal.

The high-temperature exhaust gas that has passed through the immersion tube 6 is sent to the heating space 12 after passing through the exhaust gas conduit 8 and the exhaust gas passage 11 in the furnace body 1 .

In this heating space 12, the exhaust gas exchanges heat with the outer wall surface of the crucible 4 and heats the outer wall surface of the crucible 4, so that the molten metal is heated through the crucible 4, that is, secondary heating (auxiliary heating) is performed.

The exhaust gas in the heating space 12 is discharged through a plurality of exhaust holes 13...
・It is released to the outside through.

According to the above-mentioned holding furnace, the high-temperature gas passing through the immersion tube 6 and being discharged heats the crucible 4 again in the heating space 12, so that the thermal energy obtained by the burner 7 is used in two stages. Can act on molten metal.

Therefore, most of the effective thermal energy can be absorbed by the molten metal, and the thermal efficiency can be improved to 55-65%.

Therefore, if the same melting performance as the conventional one is to be maintained, the amount of oil such as city gas, natural gas, propane gas, or heavy oil consumed by the burner 7 can be saved, which is effective for energy saving.

Furthermore, since the temperature of the gas discharged from the exhaust holes 13 becomes lower, the temperature of the working environment can also be lowered.

Further, the above configuration simply includes the exhaust gas passage 11 in the furnace body 1.
, the heating space 12, the exhaust hole 13, and so on, the implementation is easy.

It goes without saying that it is desirable to arrange the exhaust holes 13 evenly around the crucible 4 in terms of heat distribution.

In the above embodiment, a case has been described in which the exhaust holes 13 are opened on the upper surface of the furnace body 1.
As shown as a modification in the figure, the same effect can be obtained even if the exhaust holes 40 are opened on the side surface of the furnace body 1.

Furthermore, the present invention is not limited to holding furnaces for zinc die casting, but can also be applied to melting furnaces or hand furnaces for die casting of zinc, aluminum, magnesium, etc., as shown in FIGS. 5 and 6, for example. .

In FIGS. 5 and 6, parts having the same functions as those in the embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted.

As detailed above, according to the present invention, the exhaust gas from the tube burner immersed in the crucible is guided into the heating space formed between the furnace body and the outer wall surface of the crucible, and the exhaust gas remaining in this exhaust gas is guided. Since high-temperature energy is applied to the crucible to supplementally heat the molten metal inside the crucible, waste heat that would otherwise have been wasted can be used effectively, making it possible to improve thermal efficiency and contributing to energy-saving measures. It has practical effects.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a plan view, FIG. 2 is a sectional view, FIG. 3 is a sectional view of an exhaust gas pipe, and FIG. 4 is a modified example. FIGS. 5 and 6 are plan views and sectional views showing still other embodiments. 1... Furnace body, 4... Crucible, 5...
...Tube burner, 6...Immersion tube,
7...Burner, 8...Exhaust gas pipe, 1
1... Exhaust gas passage, 12... Heating space, 13, 40... Exhaust hole.

Claims (1)

[Scope of utility model registration request] In a melting furnace in which a crucible is buried in a furnace body made of a heat-resistant material, a tube burner is immersed in the crucible, and the molten metal in the crucible is heated by the tube burner, a heating space is formed between the crucible and the furnace body. A melting furnace characterized in that the crucible is auxiliary heated by guiding exhaust heat from the tube burner into the heating space.