JP2020066037A - Furnace wall structure of molten metal holding furnace - Google Patents

Abstract

To provide a furnace wall structure of a molten metal holding furnace which reduces heat dissipation from a lining layer and reduces heater capacity, and which can be easily repaired.SOLUTION: A furnace wall structure of a molten metal holding furnace 1 comprises: a lining layer 16 which directly contacts a molten metal; and a heat insulation layer 17 which is positioned on a back face of the lining layer 16. The lining layer 16 comprises: a first lining layer 16a of an integrally molded body made of monolithic refractory which constitutes a hearth and a lower side wall; and a second lining layer 16b of a heat-resistant board which constitutes an upper side wall. A joint surface 18 of the first lining layer 16a and the second lining layer 16b is positioned in the molten metal. The joint surface 18 has an uneven shape. The first lining layer 16a is an alumina-based monolithic refractory, and the second lining layer 16b is a calcium silicate-based heat-resistant board.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a furnace wall structure of a holding furnace for a molten metal used when casting a molten metal such as an aluminum alloy, and more particularly to a structure of a lining layer which is in direct contact with the molten metal.

   A furnace wall structure in a molten metal holding furnace for casting, such as a low-pressure casting molten metal holding furnace or a die casting molten metal holding furnace, has a lining layer that is in direct contact with a molten metal such as an aluminum alloy, and a heat insulating layer located on the back surface of the lining layer. (Backup layer).

  For example, in Patent Document 1, the lining layer (bath) is composed of an inner tank of an integrally formed ceramic body, and the heat insulating layer is a ceramic paper, a separation layer made of inorganic particles or inorganic fibers, and a heat insulating plate outside the inner tank. Discloses a furnace wall structure provided in this order.

  Further, Patent Document 2 discloses a furnace wall structure in which the lining layer (storage container) is a molten metal storage container formed by integrally molding an alumina amorphous refractory material.

JP-A-6-15439 JP, 2018-12131, A

  By configuring the lining layer of the furnace wall structure with heat-resistant castables as disclosed in Patent Documents 1 and 2, it is possible to obtain an arbitrary furnace shape, and further, it is easy to construct and durability. While excellent in heat conductivity, it has a higher thermal conductivity (W / m · k) than heat-resistant boards. For example, the thermal conductivity of alumina-based amorphous refractory is 2.13 to 2.62 W / m · k (at 800 ° C), while the heat resistance board of calcium silicate board is 0.15 W / m.・ K (at 400 ° C).

  By the way, in the casting work of aluminum alloy etc., the molten metal in the molten metal holding furnace for casting is supplied to the casting machine at regular intervals, and when the molten metal in the furnace decreases, new molten metal is repeatedly supplied into the furnace. ing. Therefore, the molten metal level inside the holding furnace moves up and down within a predetermined range. Further, since a strong oxide adheres to the side wall (surface of the lining layer) in the region where the molten metal moves up and down, the adhered oxide is removed at regular intervals or based on the state of the adhered oxide. There is.

  Therefore, in the furnace wall structure in which the lining layer is made of heat-resistant castable, the heat conductivity is high, so that the heat is often dissipated through the side wall exposed from the molten metal surface. Particularly, in the molten metal holding furnace for die casting, the pumping port is open to the atmosphere during the casting operation, and further, the molten metal surface is gradually lowered and the side wall area exposed to the atmosphere is gradually increased, so that the heat dissipation is remarkable. Therefore, the amount of heat required to hold the molten metal at a predetermined temperature (750 to 800 ° C.) increases, and as a result, it is necessary to increase the heater capacity for heating and holding the molten metal.

  Further, if the side wall is damaged during the work of removing the adhered oxide on the side wall surface, it is impossible to locally repair the side wall, so that the entire surface of the furnace wall cannot be avoided. Therefore, there is a problem that the repair of the furnace wall is prolonged and the repair cost is increased.

  The present invention has been made in view of the above problems, and provides a furnace wall structure of a molten metal holding furnace that reduces heat dissipation from the lining layer, reduces the capacity of the heater, and is easy to repair. Is an issue.

In order to solve the above problems, the present invention provides
A furnace wall structure of a holding furnace for molten metal, which comprises a lining layer that is in direct contact with the molten metal, and a heat insulating layer located on the back surface of the lining layer,
The lining layer comprises a first lining layer of a monolithic integrally formed refractory material forming a hearth and a lower side wall, and a second lining layer of a heat-resistant board forming an upper side wall,
The joint surface between the first lining layer and the second lining layer is located in the molten metal.

It is preferable that the joint surface has an uneven shape.
This can prevent the molten metal from entering the heat insulating layer.

  It is preferable that the first lining layer is an alumina-based amorphous refractory material and the second lining layer is a calcium silicate-based heat-resistant board.

According to the present invention, since the joint surface between the first lining layer and the second lining layer is located in the molten metal, the second lining layer forming the upper side wall is provided above the molten metal level. Exposed. The second lining layer is made of a heat-resistant board and has a low thermal conductivity, so that the amount of heat transfer from the molten metal is reduced and the amount of heat radiation from the side wall exposed to the atmosphere can be reduced. In addition, since the amount of heat radiation is reduced, the capacity of the heater installed in the furnace can be reduced.
The first lining layer on the lower side wall, which is in direct contact with the molten metal, is made of an irregular shaped refractory, so that the penetration of the molten metal into the heat insulating layer and the damage of the lining layer are reduced, and the durability is improved Can be achieved.
Even if the lining layer is damaged during the work to remove the oxides adhering to the side wall, the damaged part is the second lining layer of the heat-resistant board, so there is no need to repair the entire lining layer This has the effect of shortening the repair cost and reducing repair costs.

Sectional drawing of the holding furnace for molten metals which concerns on embodiment of this invention. II-II sectional view taken on the line of FIG. The top view of the holding furnace for molten metals of FIG. The top view of the furnace main body of the holding furnace for molten metals of FIG. The expanded sectional view of the junction part of a 1st lining layer and a 2nd lining layer. VI-VI sectional view taken on the line of FIG. VII-VII line sectional view of FIG. VIII-VIII sectional view taken on the line of FIG. IX-IX sectional view taken on the line of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a molten metal holding furnace 1 having a furnace wall structure according to an embodiment of the present invention. As shown in FIG. 4, the molten metal holding furnace 1 is composed of a molten metal receiving chamber 2, a molten metal holding chamber 3 and a molten metal pumping chamber 4, each of which has a substantially rectangular shape when viewed from above and is open upward. . The molten metal receiving chamber 2 is arranged on the left rear side when viewed from the front of the molten metal holding furnace 1, the molten metal pumping chamber 4 is arranged on the left front side, and the molten metal holding chamber 3 is arranged on the right side. The molten metal receiving chamber 2 and the molten metal pumping chamber 4 are arranged adjacent to each other via a first partition wall 5. The molten metal holding chamber 3 is arranged adjacent to the molten metal receiving chamber 2 and the molten metal pumping chamber 4 via the second partition wall 6.

  The hearth surface of the molten metal receiving chamber 2 is formed at a position higher than the hearth surface of the molten metal pumping chamber 4. The hearth surface of the molten metal holding chamber 3 is at the same height as the hearth surface of the molten metal receiving chamber 2, and part of the hearth surface of the molten metal holding chamber 3 (near the second communication opening 8 of the second partition wall 6). Has a one-step lower reservoir 3a, and the hearth surface of the reservoir 3a is formed at the same height as the hearth surface of the molten metal pumping chamber 4. As shown in FIG. 2, a first communication opening 7 that connects the molten metal receiving chamber 2 and the molten metal holding chamber 3 is formed in the lower part of the second partition wall 6, and the molten metal holding chamber 3 and the molten metal pumping chamber 4 are connected to each other. A second communication opening 8 that communicates is formed. As a result, as shown in FIG. 4, the molten metal receiving chamber 2, the molten metal holding chamber 3, and the molten metal pumping chamber 4 are viewed from above the molten metal holding furnace 1 and the molten metal is received from the molten metal receiving chamber 2 through the first communication opening 7. It is arranged in a U-shape so as to communicate with the holding chamber 3 and communicate with the molten metal holding chamber 3 through the second communication opening 8 with the molten metal pumping chamber 4.

  As shown in FIG. 3, the molten metal receiving opening 2 a above the molten metal receiving chamber 2 is covered with a heat insulating lid 9. An upper opening communicating with a lower opening (molten inlet) of the tub 10 for introducing the molten metal into the molten metal receiving chamber 2 is provided at a predetermined position of the heat insulating lid 9. A lid 11 is provided at the upper opening of the tub 10 so as to be openable and closable. The lid 11 is normally closed and is opened only when the molten metal is introduced.

  The upper opening 3b of the molten metal holding chamber 3 is covered with a heat insulating lid 12, as shown in FIG. The molten metal pumping opening 4a above the molten metal pumping chamber 4 is covered with removable heat insulating lids 13a and 13b. During operation, a part of the molten metal pumping opening 4a is closed by the heat insulating lid 13a, while the other part is opened so that the molten metal can be pumped out. When the operation is stopped, the molten metal pumping opening 4a is closed by the heat insulating lids 13a and 13b.

  An immersion heater 14 is vertically inserted into the through hole 12 a of the heat insulating lid 12 in the pool 3 a of the molten metal holding chamber 3. An immersion heater 15 is obliquely inserted into the molten metal pumping chamber 4 from the shoulder of the molten metal pumping chamber 4 to the through hole of the heat insulating lid 13a.

  The respective furnace walls of the molten metal receiving chamber 2, the molten metal holding chamber 3 and the molten metal pumping chamber 4 of the molten metal holding furnace 1 are located on the lining layer 16 that is in direct contact with the molten metal and on the back surface of the lining layer 16. It is composed of a heat insulating layer 17.

  As shown in FIG. 5, the lining layer 16 is composed of a first lining layer 16a of an integrally formed irregular refractory material forming the hearth and the lower side wall, and a second lining of a heat-resistant board forming the upper side wall. And layer 16b. The joint surface 18 between the first lining layer 16a and the second lining layer 16b is located in the molten metal. That is, the joint surface 18 is located below the lower limit LL of the molten metal surface. HL is the upper limit of the molten metal level.

  As shown in FIG. 8, the first partition wall 5 has a lower partition wall 5a that constitutes a lower wall in an integral structure with the hearth of the first lining layer 16a, and an upper partition wall 5b of a heat-resistant board that constitutes an upper wall. Consists of. The joint surface between the lower partition wall 5a and the upper partition wall 5b is located in the molten metal similarly to the lining layer 16, and the second partition wall 6 is made of a heat-resistant board, as shown in FIG. Both ends are held by the second lining layer 16b, and the lower end is located in the molten metal.

  The amorphous refractory of the first lining layer 16a is made of an alumina amorphous refractory, such as Alcon (trade name) of Calderis Co., Ltd., and its thermal conductivity is 2.62 W / m · k (800 ° C. ) Is about.

  The heat-resistant board of the second lining layer 16b, the upper partition wall 5b of the first partition wall 5 and the second partition wall 6 is made of calcium silicate board, for example, Lumiboard (trade name) of Nichias Co., Ltd. The conductivity is about 0.15 W / m · k (400 ° C). The second lining layer 16b, the upper partition wall 5b of the first partition wall 5 and the heat-resistant board of the second partition wall 6 are superposed on each other with an adhesive such as mortar.

  As shown in FIGS. 5 and 7, concave grooves 19 are formed on the upper surfaces of the first lining layer 16a and the lower partition wall 5a, and lower surfaces of the second lining layer 16b and the upper partition wall 5b are convex. A strip 20 of shape is formed. The concave grooves 19 on the upper surfaces of the first lining layer 16a and the lower partition wall 5a and the convex strips 20 on the lower surfaces of the second lining layer 16b and the upper partition wall 5b are made of an adhesive such as mortar. They are fitted to each other and joined together.

  The heat insulating layer 17 is composed of a ceramic fiber amorphous refractory in which ceramic fibers and refractory aggregate are mixed on the outside of the lining layer 16, a heat insulating filling layer such as bulk, and a heat insulating layer such as calcium silicate board.

  Next, a method of constructing the furnace wall of the molten metal holding furnace 1 will be described.

  First, as shown in FIG. 6 and FIG. 7, a plurality of heat insulating layers 17 are applied to the inside of an outer plate made of an iron skin by a heat insulating board or the like. A styrofoam mold is installed at a predetermined distance from the surface of the heat insulating layer 17 (corresponding to the thickness of the first lining layer 16a), and the alumina-based amorphous fireproof material is kneaded with water or the like between the mold and the heat insulating layer 17. The material is poured, left for a predetermined time (curing) to remove the frame, and then dried and cooled according to a predetermined temperature rising / cooling schedule to form the first lining layer 16a and the lower partition wall 5a of the first partition wall 5. To do. The upper end surfaces of the first lining layer 16a and the lower partition wall 5a are located below the molten metal holding furnace 1 for molten metal, and are positions where the molten metal is constantly immersed.

  As shown in FIG. 7, concave grooves 19 are formed in each upper end surface of the first lining layer 16a and the lower partition wall 5a, and an adhesive is applied to each upper end surface. A calcium silicate board is installed from the upper end surfaces of the first lining layer 16a and the lower partition wall 5a to the upper end of the holding furnace. The calcium silicate board is appropriately cut according to the place of installation, and a convex strip 20 that fits in the concave groove 19 of the first lining layer 16a and the lower partition wall 5a is formed on the lower end surface. A calcium silicate board is installed on the upper end surfaces of all the first lining layer 16a and the lower partition wall 5a to form the second lining layer 16b and the first partition wall 5. The second lining layer 16b and the upper partition wall 5b of the first partition wall 5 are formed by stacking one or more calcium silicate boards according to the thickness of the first lining layer 16a. An adhesive is interposed between the stacked calcium silicate boards. If necessary, the calcium silicate boards may be screwed together and laminated.

  As shown in FIGS. 4, 6 and 9, one end of the upper partition wall 5b of the first partition wall 5 of the molten metal holding furnace 1 has a concave groove 21 formed on the side surface of the second lining layer 16b. At the other end, a concave groove 21 is formed on the side surface of the second partition wall, and at both end surfaces of the second partition wall 6, a concave groove 21 is formed on the side surface of the second lining layer 16b. Each is fitted and joined through an adhesive.

  The first lining layer 16a may not be a castable structure using a mold as described above, but may be integrally molded in a predetermined shape in advance and installed in the heat insulating layer 17. In this case, the gap between the inner surface of the heat insulating layer 17 and the back surface of the integrally molded first lining layer 16a is filled with a heat insulating material such as bulk.

  In the molten metal holding furnace 1 of the embodiment described above, since the joint surface 18 between the first lining layer 16a and the second lining layer 16b is located in the molten metal, the molten metal holding furnace 1 is located above the molten metal level. The second lining layer 16b forming the upper side wall is exposed. The second lining layer 16b is made of a heat-resistant board and has a low thermal conductivity, so that the amount of heat transfer from the molten metal is reduced and the amount of heat radiation from the side wall exposed to the atmosphere can be reduced. Moreover, the capacity of the immersion heaters 14 and 15 installed in the furnace can be reduced by reducing the heat radiation amount.

  Further, since the first lining layer 16a on the lower side wall, which is in direct contact with the molten metal, is made of an amorphous refractory, penetration of the molten metal into the heat insulating layer 17 and damage to the lining layer 16 are reduced. Therefore, the durability can be improved.

  Even if the lining is damaged during the work of removing the oxides adhering to the side wall, since the damaged part is the second lining layer 16b of the heat-resistant board, it is not necessary to repair the entire lining, and the repair period can be shortened. The cost can be shortened and the repair cost can be reduced.

  Further, since the joint surface 18 of the first lining layer 16a and the second lining layer 16b has an uneven shape, it is possible to prevent the molten metal from entering the heat insulating layer 17 from the joint surface 18.

DESCRIPTION OF SYMBOLS 1 ... Molten metal holding furnace 2 ... Molten metal receiving chamber 3 ... Molten metal holding chamber 3a ... Pool part 3b ... Upper opening 4 ... Melt pumping chamber 4a ... Molten metal pumping opening 5 ... First partition wall 5a ... Lower partition wall 5b ... Upper partition Wall 6 ... 2nd partition wall 7 ... 1st communicating opening 8 ... 2nd communicating opening 9 ... Thermal insulation lid 10 ... Vat 11 ... Lid 12 ... Thermal insulation lid 12a ... Through hole 13a ... Thermal insulation lid 13b ... Thermal insulation lid 14 ... Immersion heater 15 ... Immersion heater 16 ... Lining layer 16a ... First lining layer 16b ... Second lining layer 17 ... Thermal insulation layer 18 ... Joining surface 19 ... Groove 20 ... Article 21 ... Groove

Claims (3)

A furnace wall structure of a holding furnace for molten metal, which comprises a lining layer that is in direct contact with the molten metal, and a heat insulating layer located on the back surface of the lining layer,
The lining layer comprises a first lining layer of a monolithic integrally formed refractory material forming a hearth and a lower side wall, and a second lining layer of a heat-resistant board forming an upper side wall,
A furnace wall structure of a holding furnace for molten metal, wherein a joint surface between the first lining layer and the second lining layer is located in the molten metal.   The furnace wall structure of the molten metal holding furnace according to claim 1, wherein the joint surface has an uneven shape. The furnace wall structure of a molten metal holding furnace according to claim 1 or 2, wherein the first lining layer is an alumina-based amorphous refractory material, and the second lining layer is a calcium silicate-based heat-resistant board. .

Images