JPS5950135A - Under heat type holding furnace - Google Patents

Abstract

PURPOSE:To prevent the leak of molten metal from a furnace by tapering both ends of the protective pipe of each embedding type heater so as to adhere the pipe to the wall of the furnace by the thermal expansion of the pipe in the longitudinal direction. CONSTITUTION:Both ends of the protective pipe 2 of each embedding type heater are tapered, and through holes 11, 12 are pierced in the wall 9 of a furnace at opposite positions while gradually reducing the diameter toward the outside of the wall 9. The pipe 2 is inserted into the holes 11, 12, and it is perfectly adhered to the wall 9 by the thermal expansion of the pipe 2 in the longitudinal direction. The leak of molten metal from the resulting under heat type holding furnace is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a covered underheat holding furnace used for melting metals such as aluminum.

FIG. 1 is a sectional view of an underheat type holding furnace from 11Y.

The under and -1~ type holding furnaces also have an embedded heater 5 inside the furnace.

In the conventional underheat type holding furnace, the embedded heater 5
The protective tube 17 has a straight i'-shape. For this reason, protection tubes 17 and 171! Various measures were required, such as filling the gap between the JR16 and the JR16 with Fufu-Ibar made of Shizuoka.

However, there is a limit to the sealing of graphite fibers in the gaps between the protective tubes 17 of the straights 1 to the furnace wall 1G, and the molten metal 10 gradually penetrates into the back of the protective tubes due to thermal expansion of the protective tubes after long periods of use. For this reason, during long-term furnace operation,
, 1 The molten metal 10 leaked from the joint between the protective tube 17 and the furnace wall 16, causing problems such as thermal and electrical troubles.

The present invention has been made in view of the above-mentioned circumstances, and completely prevents the leakage of molten metal from the joints between the protective tube and the furnace wall. The purpose is to avoid improving efficiency.

The under-upper mold holding furnace of the present invention has both ends of a protection tube of an embedded heater formed in a tapered shape, and utilizes the thermal expansion of the protective tube in the longitudinal direction at high temperatures. This holding furnace is characterized by a configuration in which the tapered shape of the holding furnace hearth and both ends of the protective tube are completely in close contact with each other to prevent leakage of molten metal.

Since the under-upper mold holding furnace of the present invention is constructed as described above, there is no fear that molten metal will leak from the joint with the protective tube. Therefore, the operating efficiency of the furnace is improved without any problems caused by leakage of molten metal.

Hereinafter, a preferred 4T embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view showing an example of an under-upper mold holding furnace of the present invention.

Both ends of the protection@2 are processed into a debar shape. In the embodiment, the length of the tapered portion is 7 from the length of the protective tube 2.
The taper of the 0 mI+1 portion was 1/10. Also,
The protective tube 2 was made of recrystallized SiC. The dimensions of the protection tube 2 are: the outer diameter except for the taper part is 80n++n, and the inner diameter is 60mm.
ffim, length 1200 mm. Recrystallization MS
The +C protection tube stretches at a rate of about 1 to 2 cm per meter during furnace operation.

A through hole 11 and a second through hole 12 are formed in opposing positions of the furnace wall 9. The first eyebrow through hole 11 is formed in a tapered shape on the inner side of the furnace wall 9, so as to fit in with a portion of the protector tube 2. Therefore, the first through hole 11
The taper is also 1/10. One end of the protector 2 fits into this first VJ through hole 11.

On the other hand, one end of the protective tube 2 is fitted into the second through hole 12 via one first joining ring and a second joining ring 20.

A through hole 22 is formed in the center of one first joining ring. The through hole 22 is formed in exactly the same shape as the first through hole 11, has three holes Δ', and one end of the retaining color 2 is tapered and fits into the hole. The outer diameter of the first joining ring 19 is the same as that of the second through hole 12.
Match the 1st part of
It is then formed into a tapered shape and becomes thinner.

The first bonding ring 19 connects the second through hole 12 with
~ Fits into the part. Then, a 2° 4-knot shaped portion of the second joining ring is sandwiched between a tapered portion of the second through hole 12 and a tapered portion of the first joining ring. The second joining ring 20 has a flat surface on the opposite side of the wedge-shaped portion, and is pushed in with a fastener 21 . A fastener 21G is attached to the outer surface of the side wall 9 and is configured to push the second joining ring 20 with an appropriate force.A heater 5 is installed inside the protective tube 2.

In the example, fastener 21 was made of iron. Then, attach it to the outer surface of the furnace wall 9 using Pol 1~.
child .

In this way, when the fastener 21 pushes the second joining ring 20, the second joining ring 2o pushes the first joining ring 19. Furthermore, the first joining ring 19 pushes the protective tube 2 in the longitudinal direction.

As a result, all the tapered portions come into close contact with each other and are sealed. When the furnace is operated in this state, the protection tube 2 thermally expands in the longitudinal direction, and the taper portions fit into each other, and the molten metal 10 does not leak to the outside. It is also possible to form it like the second through hole 12 and seal both sides in the same way.

The performance of the underheat type holding furnace of the present invention was compared with that of a conventional underheat type holding furnace. This comparative test will be explained next.

Approximately 500 kg of pure aluminum was melted in each of the conventional underheat type holding furnaces such as the underheat type holding furnace of the present invention, and the aluminum molten metal temperature in both furnaces was maintained at (70o±
It was held at 20>'C. The thickness of the furnace wall is 250 mm in both cases.
It was mm.

In this way, a thermocouple was inserted into the gap between the furnace wall and the protection tube,
The center position of the furnace wall is indicated by arrows A and B in Figures 1 and 2, respectively.
The temperature change at the position shown in ) was measured. The result is the third
Shown in the figure.

As shown in the graph of FIG. 3, it can be seen that in the conventional underheat type holding furnace, molten aluminum entered the gap between the protective tube and the container about 60 days after the start of the test. and,
Approximately 125 days after the start of the test, aluminum leakage was observed on the outside of the furnace wall. To prevent electrical failure of the heater due to aluminum leakage, do not shut down the furnace.

In contrast, in the underheat type holding furnace of the present invention, no temperature increase was observed even after 100 days from the start of the test, indicating that there was no intrusion of molten aluminum. Even after approximately 200 days had passed since the start of the test, no leakage of molten aluminum to the outside of the furnace could be observed.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional andal heat type holding furnace, Figure 2 is a sectional view showing an example of an underheat type holding furnace of the present invention, and Figure 413 is a sectional view of an under heat type holding furnace of the present invention and a conventional It is a graph showing the results of a comparative test of holding furnaces. 2... Protection tube 11... First shell through hole 12... Second tool through hole 19... First joining ring 20... Second joining ring 21... Fastener 22... Through hole

Claims (1)

[Claims] Place the underheater 1 in the mold holding furnace J3 used for melting metal, and taper both ends of the protection tube of the embedded heater.
The tapered shapes at both ends of the underheat type holding furnace furnace and the face protection tube are completely in contact with each other to prevent welding leakage. An underheat type holding furnace characterized by having a structure that provides 11 protection.