JP2009222239A - Crucible stand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crucible stand capable of being easily installed by humans for loading a crucible thereon in melting and/or refining metal, having long service life with high efficiency, and reducing manufacturing costs. <P>SOLUTION: This cylindrical crucible stand used in installing the crucible for melting and/or refining metal, in a crucible furnace, is constituted by stacking a plurality of cylindrical refractory members 2 in the height direction, and the refractory member is provided with a hollow section 4 vertically penetrating when the refractory members are stacked in the height direction, and a recessed groove 5 penetrating through between the hollow section and a peripheral edge section at an upper face side and/or a lower face side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a crucible base for installing a crucible in a crucible furnace for melting and / or refining metal.

  In order to perform metal melting and refining using a crucible furnace, a crucible base for placing the crucible is usually installed in the crucible furnace. This is because fuel such as gas, heavy oil, and kerosene is blown into the lower part of the furnace in a spray form and burned, so that the lower part of the furnace is a combustion chamber. In other words, if the crucible is placed on the hearth without installing the crucible stand, the combustion flame of the fuel blown from the burner hits the crucible directly, causing a temperature difference in the crucible itself and causing cracks and material changes. It becomes easy. If the metal melted from this crack leaks into the furnace, the furnace operation must be stopped. Therefore, a crucible base is placed on this part, and the crucible is placed on this crucible base so that the flame from the burner does not directly hit the crucible.

However, since the bottom of the crucible in contact with the crucible base is not directly touched by the flame from the burner, the heat transfer is slower than the crucible body, and a large temperature difference occurs in the crucible itself. Cracks due to strain tend to occur. Furthermore, since the temperature rise efficiency is also poor, it takes time to melt the metal. Therefore, a crucible base having a structure in which a gap formed by a groove that is open to the crucible bottom is provided on the upper surface of the crucible base so that the flame directly hits the bottom of the crucible is disclosed (Patent Document 1). . In addition, the bottom of the crucible in contact with the crucible base is formed by forming one vent hole penetrating in the lateral direction in the body of the crucible base, and heat is quickly transmitted to the crucible base itself through this vent hole. It is disclosed that the temperature rise at the center is prevented from being delayed compared to the bottom side surface of the crucible and the metal melting rate is increased (Patent Document 2).
JP-A-10-206026 JP-A-10-115490

  However, all of the above-described crucible stands are integral, and there are few passages of the flame inside the crucible stand. Therefore, the temperature rise time of the crucible stand itself is slow, and therefore it takes time to raise the temperature of the crucible. Further, even if the gap and the vent hole are provided, since the temperature rise time of the crucible base itself is slow as described above, the amount of heat received at the bottom of the crucible in contact with the crucible base is still small. Since the heat of the part is transmitted to the upper part through the body of the crucible, the temperature rise by heating the crucible is slow at the bottom and fast at the top of the trunk. Due to the thermal strain resulting from this temperature difference, cracks may occur in the crucible and the melted metal may leak into the furnace, forcing the operation of the furnace to stop.

  In addition, the material of the crucible base that requires high heating efficiency is usually made of graphite with high thermal conductivity. However, because graphite has low oxidation resistance, an antioxidant is added to the material itself. And an antioxidant is applied to the surface of the crucible base. However, when using a graphite crucible with high thermal conductivity in order to increase the melting efficiency of the metal, this graphite crucible is internally coated with an antioxidant as well as the graphite crucible table, so that during the operation of the furnace. The crucible antioxidant and the crucible base antioxidant are softened and welded, and the crucible and crucible base must be discarded together after use. In addition, even if anti-oxidation measures are taken on the surface of the crucible base, oxidation wear cannot be prevented completely, and the crucible base cannot support the crucible placed on it and tilts during operation of the furnace so that normal operation can be performed. Not only can it damage crucibles.

  Further, if the crucible base is an integral type, it is difficult to manually install the crucible base in the furnace from the weight side, and there is a problem in handling work that a hanging tool must be prepared. In addition, if the crucible base is an integral type, even if a part of the crucible base is damaged, the entire base must be replaced, which increases the cost of maintenance of the furnace.

  In view of the above circumstances, the present invention reduces the temperature difference of the crucible itself, thereby improving the problem that the crucible cracks due to the thermal strain resulting from the temperature difference and the molten metal leaks into the furnace. An object of the present invention is to provide a crucible base having a high service life with a high-efficiency production activity and a long service life by obtaining a homogeneous molten metal while shortening the melting time.

  A first aspect of the present invention is a cylindrical crucible base used when a crucible for melting and / or refining a metal is installed in a crucible furnace, wherein the crucible base has a high cylindrical refractory member. A plurality of the refractory members are stacked in the vertical direction, and the refractory member includes a hollow portion penetrating vertically when the refractory member is stacked in the height direction, and the upper surface side and / or the lower surface side. The crucible base is provided with a concave groove penetrating between the hollow portion and the peripheral end portion. That is, since the crucible base of the present invention has a structure in which refractory members having concave grooves are stacked, the side surface of the crucible base has an opening. The upper surface side is the surface in the crucible side direction of both surfaces of the refractory member constituting the crucible base, and the lower surface side is the surface in the hearth side direction.

  The second aspect of the present invention is a crucible base in which a plurality of the concave grooves are disposed on the upper surface side of the refractory member positioned at least on the uppermost stage. A third aspect of the present invention is a crucible base in which the uppermost refractory member is silicon carbide.

  According to the first aspect of the present invention, the crucible base is formed by stacking a plurality of cylindrical refractory members in the height direction, and the crucible base is divided in the horizontal direction. When a part of the table is damaged, it is only necessary to replace the crucible table without discarding the entire crucible table, thereby reducing the production cost and the amount of waste. Further, since the crucible base is not an integral type and is formed by stacking refractory members, it is possible to install the crucible base manually, and the handling is easy.

  Furthermore, since the crucible base can be assembled with different materials for each refractory member, the material of each part of the crucible base can be selected according to the conditions in the furnace to be used, and refractory members with different thicknesses can be selected. If prepared, the height of the crucible base can be selected at any time according to the use conditions of the furnace, so that it is not necessary to provide many types of crucible bases.

  Further, the crucible base is provided with a through hole from the opening on the side surface to the hollow portion inside. Therefore, the flame from the burner reaches the hollow portion through the concave groove, and the flame is guided upward along the hollow portion and exits from the other concave groove and the hollow portion to the outside of the crucible base. As the whole passes through the flame, the temperature of the crucible stand rises faster and the production efficiency can be increased. In addition, since the heating action from the bottom is excellent, there is no temperature difference in the crucible, a homogeneous molten metal can be obtained, and cracks occur due to thermal strain, and the molten metal leaks into the furnace. Can be resolved. Furthermore, the lateral through-hole of the crucible base only needs to be provided with a concave groove on the surface of the refractory member, and since it is not necessary to make a hole, the formation of the hole is easy. Since it can also be used as a catching part when it is lifted by, it is easy to handle even when the crucible base is not installed manually.

  According to the second aspect of the present invention, since a flame comes out along the plurality of concave grooves, the flow of the flame diffuses at the crucible bottom, and the temperature difference between the central portion and the peripheral portion becomes small at the crucible bottom. , Improve the heating efficiency of the crucible.

  According to the third aspect of the present invention, since silicon carbide has the second highest thermal conductivity after graphite, it is easy to raise the temperature by heating, and the temperature rise at the bottom of the crucible base is in contact with the place in contact with the crucible base. There is little difference between places that are not. Further, since silicon carbide does not need to contain an antioxidant and be coated on the surface like graphite, there is no problem of fusion between the antioxidants even if a graphite crucible is placed on the top.

  Next, a crucible base according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a crucible furnace and a crucible table set in a crucible furnace, FIG. 2A is a plan view showing an upper surface side of a refractory member constituting the crucible table, and FIG. a) BB schematic sectional view of the figure, FIG. 3 is a bottom view showing the lower surface side of the refractory member constituting the crucible base, and FIGS. 4, 5, and 6 are other refractory members constituting the crucible base. It is an example of this embodiment and is a plan view showing the upper surface side.

  As shown in FIG. 1, the crucible base 1 according to the embodiment of the present invention is arranged at the center on the floor of the furnace 100, and the crucible 101 is placed thereon. There is a burner port at the bottom of the side wall of the furnace 100, and a flame 104 is injected from the burner 102 provided there toward the combustion chamber 103. In this embodiment, the crucible base 1 is formed by stacking refractory members 2 in five stages.

  As shown in FIGS. 2 (a) and 2 (b), the refractory member 2 constituting the crucible base 1 according to the embodiment is cylindrical, and the hollow portion 4 is vertically arranged at the center thereof. On the upper surface side 3 of the refractory member 2, there are disposed a concave groove 5 extending from the hollow portion 4 and a concave portion 6 serving as a positioning mechanism in a portion without the concave groove 5. As will be described later, the concave portion 6 is fitted with a convex portion 10 provided on the lower surface side 8 of the other refractory member 2 in contact with the upper surface side 3 to prevent the misalignment of the stacked refractory members 2. . In addition, in the (b) figure, description of the said recessed groove 5 and the recessed part 6, and the recessed groove 9 and the convex part 10 of the lower surface side 8 was abbreviate | omitted.

  Although the dimension of the said refractory member 2 is not specifically limited, Generally, a diameter is 200 mm-400 mm, and thickness is 50 mm-100 mm. Moreover, although the diameter of the hollow part 4 is not specifically limited, 30 mm-120 mm are preferable at the point of the ease of passing through the flame 104.

  The concave grooves 5 may be provided in an appropriate number when the flame 104 is passed through the crucible base 1 and the temperature rise of the crucible base 1 is accelerated. Here, four concave grooves 5 are provided. . Further, the number of the recesses 6 may be appropriately set so that the position of the refractory member 2 constituting the crucible base 1 does not shift during use of the furnace 100, and if there are two, the position shift does not occur. Here, since the convex part 10 is provided in the lower surface side 8 of the refractory member 2 of the lowest step in contact with a hearth, the four concave parts 6 are provided from the point of stability at the time of crucible stand 1 installation.

  The recessed groove 5 extends in a tangential direction from the hollow portion 4 and reaches the peripheral end portion 7 on the upper surface side 3 of the refractory member 2. The cross-sectional shape in the width direction of the concave groove 5 is not particularly limited. In this embodiment, although not shown, the bottom has a reverse trapezoid whose width is narrower than the opening. For this reason, four inverted trapezoidal concave portions are formed in the peripheral end portion 7 of the refractory member 2. Moreover, the shape of the length direction of the ditch | groove 5 will not be specifically limited if it is a shape which a flame easily passes. In the present embodiment example, of the two side wall portions forming the concave groove 5, the side wall surface closer to the hollow portion 4 is linear, but the side wall surface on the side away from the hollow portion 4 is the hollow portion 4. The shape is bent in the shape of a circle in the vicinity. Thereby, since the flame 104 injected from the burner 102 can be oriented along the side wall of the hollow portion 4 that is circular before entering the hollow portion 4, the temperature raising efficiency of the crucible base 1 is improved. .

  The concave grooves 5 can be provided on the upper surface side 3 at an appropriate position. However, in the present embodiment, the adjacent concave grooves 5 are substantially perpendicular to each other and are arranged substantially parallel to the opposing concave grooves 5. ing. As a result, the flame 104 entering the hollow portion 4 from the outside of the crucible base through the concave groove 5 moves out of the other concave groove 5 to the combustion chamber 103 or along the wall of the hollow portion 4, and the crucible base 1 Both the inner surface side and the outer surface side are heated simultaneously.

  Moreover, it is preferable that the refractory member 2 used in the uppermost stage is provided with a plurality of concave grooves 5 on the upper surface side 3 thereof. If there are a plurality of concave grooves 5, the flow of the flame 104 diffuses at the bottom of the crucible and the temperature difference at the bottom of the crucible is eliminated, so that the temperature raising efficiency of the crucible 101 can be improved and the temperature can be raised uniformly.

  The concave portion 6 as a positioning mechanism is provided on the upper surface side 3 where the concave groove 5 is not disposed. The shape of the recess 6 is not particularly limited, such as a trapezoid or a hemisphere.

  As shown in FIG. 3, the lower surface side 8 of the refractory member 2 has a groove 9 extending in a tangential direction from the hollow portion 4 and reaching the peripheral end portion 11 of the lower surface side 8 of the refractory member 2; A convex portion 10 which is a positioning mechanism is arranged in a portion where there is no concave groove 9. Similarly to the concave groove 5 on the upper surface side 3, the concave groove 9 on the lower surface side 8 also has an appropriate number of appropriate positions when it is desired to pass the flame 104 through the crucible base 1 to accelerate the temperature rise of the crucible base 1. Should be arranged. In this embodiment, four concave grooves 9 on the lower surface side 8 are provided in the same shape as the concave grooves 5 at positions where they can be opposed to and matched with the concave grooves 5 on the upper surface side 3. For this reason, when the refractory member 2 is stacked, a lateral through hole is formed in the crucible base 1 by the concave groove 9 on the lower surface side 8 and the concave groove 5 on the upper surface side 3.

  The convex portion 10 provided on the lower surface side 8 is fitted with the concave portion 6 provided on the upper surface side 3 of the other refractory member 2 in contact with the lower surface side 8, and the positional deviation of the stacked refractory members 2 is shifted. To prevent. Therefore, the position, shape, and number of the convex portions 10 correspond to the concave portions 6. However, since the size of the convex portion 10 is slightly smaller than the size of the concave portion 6, the convex portion 10 and the concave portion 6 can be easily fitted to each other, so that the efficiency of stacking the refractory members is improved. When the convex portion 10 and the concave portion 6 are two pairs, the bottom refractory member 2 is not provided with the convex portion 10 on the lower surface 8 from the viewpoint of the stability of the crucible base 1. Good. In addition, by reversing the vertical positional relationship between the concave and convex portions, a concave portion may be provided on the lower surface side 8 of the refractory member 2 and a convex portion may be provided on the upper surface side 3. From the viewpoint of the stability of the crucible placed on the plate, one without a convex portion may be used.

The material of the refractory member 2 is not particularly limited as long as it has high fire resistance and can withstand a hot load. For example, silicon carbide (SiC), silica-alumina (SiO ₂ -Al ₂ O ₃ ), etc. Can be mentioned. Since the SiC material has high thermal conductivity and does not apply an antioxidant, it does not soften and weld with the antioxidant of the graphite crucible 101. Therefore, it is used as the uppermost refractory member 2 in contact with the crucible 101. Preferably, it may be used in a stage other than the uppermost stage for raising the temperature of the entire assembled crucible table. The SiO ₂ —Al ₂ O ₃ material is preferable in that it is stable in an oxidizing atmosphere and is inexpensive in terms of price, and it is preferable to use a large amount other than the uppermost stage.

  Next, a method of using the crucible base of the present invention will be described based on the embodiment of FIG. When the furnace 100 is small, bend down and put the head into the furnace by human power, and when the furnace 100 is large, a human enters the furnace and hangs the refractory member 2 by manpower. The crucible base 1 is assembled, for example, by stacking five stages at the center. Since the crucible base 1 has a structure divided into five in the horizontal direction, a large force is not required for the installation, and the working efficiency is improved. Moreover, when assembling the crucible base 1, the height of the crucible base 1 can be adjusted by selecting the thickness and the number of steps of the refractory member 2, and further by selecting the material for each refractory member 2 according to the use conditions. There exists an advantage which can select the material of each site | part of the crucible stand 1 arbitrarily. At this time, the concave portions and the convex portions, which are positioning mechanisms, are fitted and stacked to prevent the displacement of the respective refractory members 2.

  As shown in FIG. 1, since the heating burner 102 is provided on the side wall of the lower part of the furnace 100, the refractory is set so that the flame 104 of the burner 102 enters at least one of the concave grooves provided on the upper and lower surfaces. It is preferable to stack the object members 2. After assembling the crucible base 1, the crucible 101 is placed on the crucible base 1 and the furnace lid is put on, and the operation of the furnace 100 is started.

  Next, another embodiment of the present invention will be described. In the above-described embodiment, the four concave grooves 5 on the upper surface side 3 and the four concave grooves 9 on the lower surface side 8 have side walls on the side away from the hollow portion 4 in the vicinity of the hollow portion 4. As shown in FIG. 4, both the wall surfaces are straight concave grooves 13, and as shown in FIG. 5, the linear concave grooves 15 are formed in the normal direction from the hollow portion 4. It may be stretched. In the embodiment shown in FIG. 5, since the four concave grooves 15 are arranged in a cross shape, the flame 104 is easy to pass through, and the temperature of the crucible base 1 can be increased uniformly. Furthermore, as shown in FIG. 6, an arcuate groove 16 may be used. At this time, the concave grooves on the lower surface may be arranged in the same shape as the concave grooves 13, 15, 16 at positions where they can be opposed to the straight concave grooves 13, 15 and the arc-shaped concave groove 16, respectively. Good.

  In the above-described embodiment, four recesses 6 are provided on the upper surface side 3, but as shown in FIGS. 4, 5, and 6, the recesses 14 and 17 that are positioning mechanisms on the upper surface side 3 are , Each may be two. At this time, although not shown, two convex portions are provided at positions corresponding to the concave portion 14 and the concave portion 17 on the lower surface side.

  Furthermore, in the above-described embodiment example, the cross-sectional shape of the concave groove 5 and the concave groove 9 in the width direction is an inverted trapezoid, but the flame 104 only needs to pass through the concave groove 5 and the concave groove 9, so The shape is not particularly limited, such as a circular shape or a shape obtained by dividing a polygon into half. Similarly, the cross-sectional shapes in the width direction of the concave groove 5 on the upper surface side 3 and the concave groove 9 on the lower surface side 8 do not have to be the same, as long as the flame 104 passes through. In the embodiment, the refractory member 2 has a cylindrical shape in order to improve the heating efficiency by allowing the flame 104 to smoothly move around the crucible base 1. However, if necessary, the refractory member 2 has a cylindrical shape. Instead of a frustum, a polygon, or the like may be used.

Hereinafter, examples of the crucible table according to the present invention will be described. The refractory members of Examples 1 to 3 were made of SiO ₂ —Al ₂ O ₃ and SiC. The structures of the crucible bases of Examples 1 to 3 are each a round refractory member having Φ290 mm × height 330 mm × thickness 90 mm, and a circular refractory member having Φ290 mm × height 330 mm × thickness 60 mm. Stacked from the top to the 4th stage from the top, this was assembled in the center of the hearth as a cylindrical crucible base having a height of 330 mm made of a total of 5 refractory members. Here, each refractory member is formed in a semicircular arc-like shape arranged symmetrically as shown in FIG. 5 having a hollow portion penetrating up and down of Φ70 mm in the central portion and a width of 45 mm on each of the upper surface side and the lower surface side. It has two concave grooves and two pairs of concave and convex portions that are positioning mechanisms. A crucible having a bottom diameter of 280 mm and a height of 650 mm was placed there. Aluminum was used as the molten metal. Table 1 shows characteristics characteristic of the quality of the SiO ₂ —Al ₂ O ₃ and SiC refractory members used in the examples and the quality of the graphite refractory member used in the comparative examples.

In Example 1, a crucible base is assembled using SiO ₂ -Al ₂ O ₃ refractory material corresponding to material 1 in Table 1 in all the first to fifth stages, and the time required to start melting of aluminum, when all are melted The hot water temperature and the required time and the service life were measured. The results are shown in Table 2.

In Example 2, the refractory member made of SiC corresponding to material 2 in Table 1 is used in the uppermost stage, and the refractory member made of SiO ₂ —Al ₂ O ₃ equivalent to material 1 shown in Table 1 is used in the second to fifth stages. Were assembled, and the time required to start melting aluminum, the temperature and time required for melting the whole amount, and the service life were measured. The results are shown in Table 2.

In Example 3, a SiC refractory member corresponding to the material 2 in Table 1 is provided on the uppermost stage and the third stage from the top, and SiO ₂ —Al ₂ O corresponding to the material 1 in Table 1 on the second, fourth, and fifth stages from the top. _A crucible base was assembled using _three refractory members, and the time required to start melting aluminum, the temperature and time required for melting the whole amount, and the service life were measured. The results are shown in Table 2.

  In addition, as a comparative example, an integral crucible base having a solid cylindrical shape, the time required to start melting of aluminum when using a graphite crucible base corresponding to material 3 in Table 1, hot water at the time of melting the whole amount Temperature and duration, and service life were measured. The results are shown in Table 2.

  As shown in Table 2, when the aluminum melt-off time and the temperature adjustment time of the molten metal of the graphite-integrated crucible base as a comparative example are 100%, the aluminum melt-off time of the examples is 64% to 78%, The temperature adjustment time was 31% to 60%, and the operation efficiency of the furnace was improved. Moreover, while the temperature difference of the hot water temperature at the time of the total amount melting of a comparative example is 52 degreeC, in the Example, it became 27 to 33 degreeC, and the molten metal with a small upper and lower temperature difference was obtained. Furthermore, since the useful life of the example was four times or more that of the comparative example, the production cost could be reduced and the number of maintenance stoppages and maintenance work could be reduced.

  Since the crucible base is formed by stacking refractory members, the crucible base can be installed by human power, and the height of the crucible base can be selected at any time, which is highly useful in the field of crucible furnaces.

It is a schematic sectional drawing of the state which set the crucible and the crucible stand in the crucible furnace. (A) The figure is a top view of the refractory member which comprises a crucible stand, The same (b) figure is the bb line schematic sectional drawing of (a) figure. It is a bottom view of the refractory member which comprises a crucible stand. It is a top view which shows the example of 1st other embodiment of the refractory member which comprises a crucible stand. It is a top view which shows the 2nd other embodiment example of the refractory member which comprises a crucible stand. It is a top view which shows the 3rd other example of an embodiment of the refractory member which comprises a crucible stand.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crucible base 2 Refractory member 3 Refractory member upper surface side 4 Hollow part 5 Concave groove 6 Concave part 7 Perimeter end part 8 Refractory member lower surface side 9 Concave groove 10 Convex part 11 Peripheral end part 13 Concave groove 14 Concave part 15 Concave groove 16 Concave groove 17 concave

Claims (3)

A cylindrical crucible base used when a crucible for melting and / or refining metal is installed in a crucible furnace,
The crucible base is a stack of a plurality of cylindrical refractory members in the height direction,
The refractory member has a hollow portion that vertically penetrates when the refractory member is stacked in the height direction, and passes between the hollow portion and the peripheral end portion on the upper surface side and / or the lower surface side. A crucible stand with a recessed groove.   The crucible base according to claim 1, wherein a plurality of the concave grooves are arranged at least on the upper surface side of the refractory member located at the uppermost stage. The crucible base according to claim 2, wherein the uppermost refractory member is made of silicon carbide.

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