JPH03207988A - Apparatus for measuring temperature of molten metal of induction heating furnace - Google Patents

Abstract

PURPOSE:To enhance durability and response and to perform continuous thermometry by exposing the temp. sensing part provided to the leading end of a thermometer to the vicinity of the furnace bottom of a furnace body and fixing the thermometer to the furnace body from the outside thereof in pierced state in a freely detachable manner using a liquidtight device. CONSTITUTION:A thermometer 4 is mounted to a furnace body 3 in the vicinity of the furnace bottom 3a through a refractory block 5 and set to the height not coming into contact with the slag 1a on a molten metal 1. The outer periphery of the refractory block 5 is formed into a tapered shape to be fixed to the furnace body 3. The inside opening of the insertion hole 6 permitting the thermometer 4 to pass is formed into a tapered shape larger than the outer shape of the leading end temp. sensing part 4a of the thermometer 4 and the vicinity of the inside opening between the thermometer 4 and the insertion hole 6 is filled with powdery curable refractory 7a, for example, consisting of the alumina wet stamp material and a binder and the outside opening between them is filled with powdery non-curable refractory 7 composed of alumina or magnesia or a mixture of them. The refractory 7a enhances the liquidtightness to a molten metal and the refractory 7b facilitates scraping-out and filling. The leading end temp. sensing part 4a is exposed to the recessed part 8 of the furnace body and, in the recessed part 8, the leading end temp. sensing part 4a is always in contact with the molten metal to secure accurate thermometry and protected from damage.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a method for melting objects to be heated such as metal in an induction heating furnace such as a groove induction furnace or a coreless induction furnace, and for keeping the temperature of the melted molten metal. Regarding the molten metal temperature measurement device for induction heating furnaces,
Continuous temperature measurement is used to operate for hours, to operate mainly at night using nighttime electricity and reduce the operating rate during the day, and to maintain the temperature of the molten metal to the extent that it does not solidify in preparation for the next operation during the day. This relates to a molten metal temperature measuring device for induction heating furnaces that can be used for induction heating furnaces.

[Prior art] Regarding the conventional technology of a molten metal temperature measuring device for an induction heating furnace,
FIG. 4 is a sectional view of Conventional Example 1, and FIG. 5 is a sectional view of Conventional Example 2 and Conventional Example 3.

In FIG. 4, in order to measure the temperature of the molten metal 1 in the furnace body 43, a thermometer 44 equipped with a tip temperature sensing part 44a with a holder 44b is manually or mechanically placed under the slag 1a each time the temperature is measured. The temperature is measured by immersing the tip temperature sensing portion 44a in the molten metal 1, and the temperature measurement is not continuous, so there is no need for the thermometer to have continuous heat resistance.

Conventional example 2 in FIG. 5 is a furnace body 53 equipped with an induction heating coil.
A thermometer 54 consisting of a thermocouple with a ceramic protection tube 54b can be fixed to the upper lid 55, and the temperature can be continuously measured by inserting the tip temperature sensing part 54a into the molten metal 1 under the slag 1a at all times or when necessary. If used for a long period of time, the protective tube 55b will be eroded by the slag La, and it is impossible to know when the thermometer will be damaged, requiring periodic replacement, and the durability for long-term continuous temperature measurement is poor.

Conventional Example 3 in FIG.
The temperature of the molten metal is continuously measured through a refractory with a thickness of ~20B, and although the durability of the thermometer is improved, the temperature response is extremely poor over time, and there is a temperature gradient with the molten metal. Temperature measurement errors occur.

Although not shown in the figure, there is a method of continuously measuring temperature using a radiation thermometer as a conventional example 4, but when slag or melting materials are on the surface of the molten metal, the true temperature cannot be measured, and the emissivity of gas on the surface of the molten metal cannot be measured. temperature measurement errors are likely to occur due to changes in temperature, and a gas barge may be required for the temperature measurement surface.

[Problem to be solved by the invention]

The purpose of this invention is to review the above-mentioned conventional techniques, and to
In particular, continuous operation is required to operate 24 hours a day, to operate mainly at night using nighttime electricity and reduce the operating rate during the day, and to maintain the temperature of the molten metal to the extent that it does not solidify in preparation for the next operation during the day. The object of the present invention is to provide a molten metal temperature measuring device for an induction heating furnace that can measure temperature, and the specific problems are as follows.

(a) The temperature of molten metal such as cast iron can be measured continuously and stably for a long period of time (for example, 6 months or more).

(b) The thermometer protection tube should not come into contact with the slag on the surface of the molten metal.

(c) The thermometer protection tube is not exposed to the atmosphere (during furnace operation).

(d) The thermometer protection tube must have heat resistance of, for example, 1300-1650°C and be resistant to thermal shock.

(6) The temperature of the molten metal can be measured more accurately and the response speed is fast.

(f) The temperature measuring device must be resistant to mechanical shocks such as when materials are added.

(g) The thermometer can be replaced easily and in a short time while the molten metal remains in the furnace.

(h) Even if the thermocouple is damaged and temperature measurement becomes impossible, hot water temperature measurement can continue.

[Means for Solving the Problems] In the molten metal temperature measuring device for an induction heating furnace according to the first aspect of the invention, the tip temperature-sensing part of a thermometer that penetrates the furnace body from the outside is exposed near the bottom of the furnace body, and the temperature sensing device can be attached or detached. The thermometer is fixed to the furnace body from the outside using a flexible liquid-tight device.

In the molten metal temperature measuring device for an induction heating furnace according to Invention 2, in Invention 1, the liquid-tight device has an inner opening slightly larger than the outer diameter of the temperature sensing portion at the tip of the thermometer on the inside of the furnace body, and an inner opening on the outside of the furnace body. It consists of an insertion hole formed in the furnace body with an outer opening larger than the opening, and a powdered refractory filled between the insertion hole and the thermometer.

In the molten metal temperature measurement device for an induction heating furnace according to Invention 3, in Invention 2, the powdered refractory includes a hardened refractory near the inner opening of the insertion hole and a non-hardened refractory on the outside opening side of the hardened refractory. It consists of a hardened refractory.

In the molten metal temperature measuring device for an induction heating furnace according to a fourth aspect, in the second or third aspect, the insertion hole is a refractory block formed separately from the furnace body, and the outer periphery of the refractory block is small inside the furnace body. It has a large shape on the outside of the body and is fixed to the furnace body.

A molten metal temperature measuring device for an induction heating furnace according to a fifth aspect of the present invention is, in any one of the first to fifth aspects of the invention, a temperature sensing device for molten metal in an induction heating furnace, wherein the tip temperature sensing part of the thermometer is attached to the furnace body or the refractory block at a portion exposed to the furnace body. A recess that opens inward is provided.

In the molten metal temperature measuring device for an induction heating furnace according to Invention 6, in Invention 1 or 2, the thermometer includes a cylindrical protection tube made of alumina-based ceramics having a bottom, a thermocouple in the protection tube, and a thermocouple in the protection tube. It consists of a powdered refractory filled between the thermocouple and the protective tube.

A molten metal temperature measurement device for an induction heating furnace according to a seventh aspect of the present invention is any one of the first to fifth aspects, wherein a plurality of the thermometers are provided in the furnace body.

[Effect]

Invention 1 pours molten metal from the furnace body for the next process,
Even if the amount of molten metal in the furnace changes due to the reception of new molten metal or the introduction of new materials, as long as the operation is carried out to ensure some molten metal at the bottom of the furnace, the temperature sensing part at the tip of the thermometer will is immersed in molten metal at all times, even 24 hours a day, and the temperature-sensitive tip is not exposed to slag or the atmosphere, improving durability and ensuring accurate temperature measurement and good responsiveness. Item (a
), (b), (C), (e) and (g)). The thermometer is removable with a liquid-tight device (powdered refractories, heat-resistant packing, etc.), so even if there is some molten metal, you can tilt the furnace body and tilt the molten metal in the area where the thermometer is located to replace the thermometer. is easy (corresponds to item (g)).

Invention 2, in addition to the effects of Invention 1, uses a powdered refractory as a liquid-tight device between the insertion hole of the furnace body and the thermometer, and since the insertion hole is large on the outside of the furnace body, powder is removed when replacing the thermometer. It becomes easier to scrape out and fill the shaped refractories (corresponds to (g)).

Invention 3, in addition to the effect of Invention 1, is that the refractory near the inner opening of the insertion hole is hardened and keeps the molten metal liquid-tight, and the refractory near the outer opening is non-hardened, so the liquid-tightness is maintained. This makes scraping and filling easier (corresponds to (g)).

Invention 4, in addition to the effects of Invention 2 or 3, since the insertion hole is formed in the refractory block separately from the furnace body, the shape and material of the insertion hole can be made appropriate, and the refractory block is It is fixed to the body in the form of a taber, etc., and can be replaced from outside the furnace if necessary. At this time, if there is some molten metal, it is best to tilt the furnace so that there is no molten metal in the refractory block area (
(corresponds to (g)).

Invention 5 has, in addition to the effects of any of Inventions 1 to 4,
Since the tip temperature sensing part is exposed in the recess that opens inside the furnace body, there is less chance of the input material hitting the tip temperature sensing part and damaging it, and contact with the molten metal is maintained at all times ((e) and (f) ).It is better to point the thermometer horizontally near the bottom of the hearth.

Invention 6, in addition to the effects of Invention 1 or 2, uses alumina-based ceramic sock as the protective tube of the thermometer, so it has sufficient durability against the temperature of molten metal such as cast iron (1300 to 1650°C). ), (d) and (f)), Invention 7 has the effect of any one of Inventions 1 to 5,
If one thermometer should be damaged, another thermometer can be used immediately (corresponding to (a) and (h)).

〔Example〕

FIG. 1 is a sectional view of the embodiment, FIG. 2 is a vertical sectional view of a furnace using the furnace shown in FIG. 1, and FIG. 3 is a plan view of FIG. 2.

In these figures, a thermometer 4 is mounted via a refractory block 5 near the bottom 3a of a furnace body 3 forming a chamber 2 for holding molten metal 1, and is in contact with slag la above molten metal 1. Not located at a height. The outer periphery of the refractory block 5 is fixed to the furnace body 3 in a tapered shape, which is smaller on the inside of the furnace body and larger on the outside of the furnace body.

Insertion hole 6 for passing thermometer 4 inside fireproof block 5
The inner opening is slightly larger than the outer shape of the temperature sensitive tip 4a of the thermometer 4, and the outer opening is larger than the inner opening,
The insertion hole 6 has a tapered shape, for example.

In the vicinity of the inner opening between the thermometer 4 and the insertion hole 6, there is a powdered hardened refractory 7a made of, for example, a 75-85% alumina wet stub material and a binder, and on the outer opening side. For example, a powdered non-hardened refractory 7b made of high alumina, magnesia, or a mixture of the two is filled. The refractory material 7a increases the liquid tightness against the molten metal, and the refractory material 7b
It is easier to scrape out and fill.

The tip temperature sensing portion 4a of the thermometer 4 is exposed from the refractory block 5 into the furnace, and the exposed tip temperature sensing portion 4a is exposed to the furnace body 3 (3a).
A recess 8 that opens into the furnace is formed in the refractory block 5.
The tip of the refractory block 5 may be extended to the inner wall of the furnace body 3 (3a), and a recess 8 may be provided in the refractory block 5. The recess 8 is the tip temperature sensing part 4
A constantly contacts the molten metal to ensure accurate temperature measurement, and also reduces collisions of input materials to protect them from damage.

Therefore, it is best to point the thermometer horizontally near the bottom of the hearth.

The internal structure of the thermometer 4 is not particularly shown, but if the molten metal is cast iron, a cylindrical bottom with a high alumina type, such as ceramics with 95% or more alumina, is used, and the inner tip is made of platinum. Place rhodium thermocouples and fill with powdered refractory,
Install a terminal box. The thermometer is not limited to a thermocouple, but may also be a platinum resistance thermometer, for example, and the material of the protective tube can be selected depending on the temperature and properties of the molten metal.

A plurality of thermometers 4 are provided in case of damage.

To briefly explain the structure of the furnace body 3 and the fixing structure of the thermometer 4 and the refractory block 5, the furnace body 3 is equipped with a tap hole 3b, and is backed up by a refractory brick 20, an insulating brick 21, an insulating board 22, and an outer shell 23. Although a groove-shaped inductor 25 is attached via the throat 24, the induction heating method is not limited to the inductor, and other induction heating methods such as a coreless induction method can be used. The fireproof block 5 is fixed to the outer shell 23 with a flange 26 and bolts 27, and the flange 28 into which the base of the thermometer 4 is screwed is fixed to the flange 26 with bolts 29. The flange 28 is provided with a plurality of small holes 28a filled with powdered refractories 7a, 7b. To remove the thermometer 4, remove the flange 28 from the flange 26 for each of the refractories 7a and 7b.

A modification of the above embodiment will be explained.

In addition to being tapered, the insertion hole 6 may be a short cylinder with a small diameter on the inside and a long cylinder with a large diameter on the outside, or may be tapered, and the same applies to the fireproof block 5.

Powdered refractory 7 filled between insertion hole 6 and thermometer 4
A heat-resistant packing may be used as a liquid-tight device in place of a and 7b. At that time, a packing may be attached to the stepped surface of the opening of the cylinder, or a packing may be provided at the flange 28 to make the gap between the insertion hole 6 and the entire cylindrical portion of the thermometer 4 small.

The insertion hole 6 is inserted directly into the furnace body 3 without using the refractory block 5.
Alternatively, the taper of the refractory block 5 may be reversed, and it may be installed from inside the furnace body 3 and fixed with heat-resistant adhesive, cement, etc., and the static pressure of the molten metal may be utilized.

〔Effect of the invention〕

The molten metal temperature measuring device for induction heating furnaces of this invention group exposes the tip temperature-sensing part of the thermometer that penetrates the furnace body from the outside near the bottom of the furnace body, and uses a removable liquid-tight device. Since the thermometer is fixed to the furnace body from the outside of the furnace body, the temperature-sensing part at the tip of the thermometer can always be located in the molten metal, and if a certain amount of molten metal is secured, the slag will not be exposed to the atmosphere. It has the advantage of being durable and does not come into contact with other objects, the temperature readings are accurate and the response speed is fast, and the thermometer can be replaced by tilting the furnace even while the molten metal is still in the furnace. be.

Therefore, in particular, in order to operate 24 hours a day, to operate mainly at night using nighttime electricity and reduce the operation rate during the day, and to keep the molten metal warm during the day to the extent that it does not solidify in preparation for the next operation, Capability of continuous temperature measurement. A molten metal temperature measuring device for a 2+ induction heating furnace is obtained.

Inventions 2 to 4 have the effect that the thermometer can be replaced easily, and Invention 5 has the effect that the recess allows the temperature sensing part at the tip of the temperature needle to be easily replaced by inserting the material without impairing the temperature measurement function. It has the effect of preventing damage, and invention 6 makes it possible to measure the temperature of high-temperature molten metal such as cast iron, and invention 7 allows for permanent continuous measurement by operating a spare thermometer even if the thermometer is damaged. Each has its own effect on increasing warmth.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the embodiment, Fig. 2 is a longitudinal sectional view of a furnace using the furnace shown in Fig. 1, Fig. 3 is a plan view of Fig. 2, and Fig. 4 is a sectional view of Conventional Example 1. 5 are cross-sectional views of Conventional Example 2 and Conventional Example 3. 1... Molten metal, 1a... Slag, 3,43.53...
・Furnace body, 3a...Furnace bottom, 4,44.54.57...
Thermometer, 4a. 44a. 54a...Tip temperature sensing part, 5.
...Refractory block, 6...Insertion port, 7a...Hardened refractory, 7b No.l Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1) The tip temperature sensing part of a thermometer that penetrates the furnace body from the outside is exposed near the bottom of the furnace body, and the thermometer is connected to the furnace using a removable liquid-tight device. A molten metal temperature measuring device for an induction heating furnace, characterized in that it is fixed to the furnace body from outside the body. 2) In the molten metal temperature measurement device for an induction heating furnace according to claim 1, the liquid-tight device has an inner opening slightly larger than the outer diameter of the temperature sensing portion at the tip of the thermometer on the inside of the furnace body, and an inner opening on the outside of the furnace body. An induction heating furnace comprising an insertion hole formed in the furnace body with an outer opening larger than the opening, and a powdered refractory filled between the insertion hole and the thermometer. Molten metal temperature measuring device. 3) In the molten metal temperature measurement device for an induction heating furnace according to claim 2, the powdered refractory includes a hardened refractory near the inner opening of the insertion hole and a non-hardened refractory near the outer opening of the hardened refractory. A molten metal temperature measuring device for an induction heating furnace, characterized by comprising a hardened refractory. 4) In the molten metal temperature measuring device for an induction heating furnace according to claim 2 or 3, the insertion hole is a refractory block formed separately from the furnace body, and the outer periphery of the refractory block is small inside the furnace body. A molten metal temperature measuring device for an induction heating furnace, characterized in that it has a large shape on the outside of the body and is fixed to the furnace body. 5) In the molten metal temperature measuring device for an induction heating furnace according to any one of claims 1 to 4, the tip temperature sensing portion of the thermometer is attached to the furnace body or the refractory block at a portion exposed to the furnace body. A molten metal temperature measuring device for an induction heating furnace, characterized by having a recess that opens into the furnace. 6) In the molten metal temperature measuring device for an induction heating furnace according to claim 1 or 2, the thermometer comprises a cylindrical protection tube made of alumina ceramics having a bottom, a thermocouple in the protection tube, and a thermocouple in the protection tube. A molten metal temperature measuring device for an induction heating furnace, characterized in that it is made of a powdered refractory filled between a thermocouple and the protection tube. 7) The molten metal temperature measuring device for an induction heating furnace according to any one of claims 1 to 5, wherein a plurality of the thermometers are provided in the furnace body.