JP2003164952A - Conical ladle for centrifugal casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that a molten metal outlet of a conical type ladle for centrifugal casting is damaged by thermal shock and the like and must be mended for each casting. <P>SOLUTION: The molten metal outlet 2, i.e., a head of a tilting base 1 of the conical type ladle, is formed by a compound refractory layer together with an inner iron plate 21 installed vertically on an enclosed iron plate 11 up to the top surface of a refractory mortar 13, a porous iron plate 22 fastened perpendicular to the enclosed iron plate 11 in parallel with the inner iron plate 21 at intervals, which is integrally bonded to the inner iron plate 21 by using both a front refractory mortar 25 covering both sides of the iron plate while filling and communicating numerous porosity 23 of the iron plate and a rear refractory mortar 24. As the integrally bonded compound refractory layer will not be fallen off even if a gap or a crack is generated when used, it may bring a marked improvement in durability than ever before. In practice, an open area ratio of the porous iron plate is 5-35%, most desirably 20%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triangular ladle frequently used in centrifugal casting.

[0002]

2. Description of the Related Art A triangular ladle has been conventionally used as a ladle suitable for centrifugal casting. FIG. 5 is a cross-sectional view for explaining the principle of the centrifugal force casting method. When the molten metal M is poured onto the inner surface of the mold A that rotates at a high speed, the molten metal M is generated by the centrifugal force acting in the mold. It flows so as to be pressed toward the inner peripheral surface of the mold, and forms a cylindrical molten layer P having a thickness corresponding to the pouring amount. If the metal solidifies and cools with the centrifugal force applied, a cylinder with the desired wall thickness can be obtained.
Strict control for each casting is a very important factor in maintaining the accuracy of product dimensions.

Therefore, the molten metal M received from a metal melting furnace (not shown) is temporarily melted by a predetermined pouring amount in the triangular ladle 1.
0, then one end of the triangular ladle (upper left end in the example in this figure) is pulled up and the entire triangular ladle is tilted in the direction of the arrow to keep the pouring amount in the triangular ladle constant. The whole amount is transferred in proportion to the mold through the gutter. As a result, the control of the pouring amount and pouring speed is accurately maintained, and a sound metal cylindrical pipe of the correct size can be cast.

Most of centrifugal casting is a ductile cast iron pipe, which is mainly used for water supply, sewage, gas, etc. The molten metal temperature in this case is about 1200 to 1300 ° C.,
The fire resistance structure of the triangular ladle does not cause any serious damage, and the burden of daily repair and inspection is not great. FIG. 3 is a perspective view of the triangular ladle 10 and shows a posture when the molten metal is received from the melting furnace. The outer peripheral surface is an outer steel plate 1
11 and has a fan-shaped cross section. The cross section taken along the one-dot chain line XX in the same figure is the tilting bottom surface 101 shown in FIG. 4, and when the triangular ladle 10 tilts, the molten metal inside flows over the top surface of this tilting bottom surface 101 to the outside. Is discharged. The tilted bottom surface 101 has a structure in which a refractory brick 112 lined inside is spread over the outer iron plate 111, and a refractory mortar 113 that covers the entire top surface and fills the brick joint is further formed. As the refractory mortar, for example, one prepared by kneading alumina ceramics and water glass to prepare a mortar is used.

The tip end side of the tilting bottom surface 101 serves as a tap hole 102. The tap 102 is placed on the outer iron plate 111 and the inner iron plate 1
21 is erected to serve as a support for the refractory brick 112 from being displaced or slid down by the eccentric load when the triangular ladle is tilted. If this interior iron plate 121 is exposed, it will constantly come into contact with the flowing molten metal to melt it, so that the tip side should be covered with a refractory mortar layer 124 of a desired thickness to protect it from thermal shock. I am configuring.

[0006]

In the case of the ductile cast iron pipe, which is the main component of the centrifugal casting method, the molten metal temperature remains at about 1200 to 1300 ° C as described above, and therefore the durability of the triangular ladle is not so great. No big problems occur. However, when the molten metal is not a cast iron type but a cast steel type (including special steel), the molten metal temperature is delicately controlled by the chemical composition, product volume, and shape. It is markedly high at 1700 ° C, and the fluidity of the molten metal itself (flow of molten metal) is remarkably inferior to that of cast iron systems of high carbon and high silicon. For this reason, the operating environment such as thermal shock to the refractory lining of the triangular ladle must be severe.

It is the area around the outlet that is exposed to the most severe conditions. The thermal energy that has continuously gathered while maintaining a large surface converges to one point at this outlet and changes into a turbulent flow, which causes a dramatic change in flow velocity and maximum thermal shock. Since the fluid having a large specific gravity concentrates and flows down on the surface, the dynamic impact accompanied by rubbing is also the maximum. Moreover, originally, the adhesiveness between the interior iron plate 121 and the refractory mortar 124 is not necessarily good,
Only after repeated use, voids are generated in this adhesive surface, which triggers the exfoliation of the refractory mortar. Once peeling of even a small portion of the refractory mortar begins to become difficult as a ladle, peeling off all the refractory mortar in the vicinity and reattaching it again is a full repair of the tap. In the case of cast steel including special steel, it is used only once before partial repair, and twice on average until full repair is performed. However, the increase of the repair time and the decrease of the work efficiency obviously impose a heavy burden.

The prior art disclosed in Japanese Unexamined Patent Publication No. 10-296427 relates to strengthening a ladle for casting a non-ferrous metal die casting product into a die casting machine or a gravity mold, and repeatedly uses a molten metal as a container for scooping a required amount. In addition to the previous application in which a ladle is molded with ceramic fiber and a metal net or metal plate is embedded inside it to reinforce it, and at the same time, a heat-resistant cloth material is embedded at least on the bottom surface of the ladle to double strengthen it. . Here, the heat resistant cloth material is a heat resistant cloth formed by weaving a wire material of SiO ₂ : 80% or more, and the metal net or the metal plate to be embedded is set and reinforced so as to withstand the weight of the molten metal received. The ladle is also common with the triangular ladle that is the object of the present invention in that it is a container for scooping and casting molten metal in a fixed amount, but this prior art is an Al alloy with a melting point of 660 ° C. and a specific gravity of only 2.7. Even if it can be applied to such cases, it can be said that thermal shock and dynamic shock are only in different technical fields compared to the triangular ladle that targets cast steel melt with a specific gravity of 7.6 that reaches 1700 ° C. .

In order to solve the above-mentioned problems, the present invention needs to repair the refractory layer that peels off every time it is used almost every time, and at least several times the tap of the triangular ladle used for centrifugal force casting for cast steel. The purpose is to improve the structure so that it can be continuously used about 10 times.

[0010]

In a triangular ladle for centrifugal casting according to the present invention, a tilting bottom surface 1 which is one side of a fan-shaped cross section is formed by accumulating an outer shell iron plate 11, a refractory brick 12 and a refractory mortar 13. The tap hole 2 which is the tip of the tilting bottom surface 1 is placed on the outer iron plate 11 in parallel with the inner iron plate 21 standing up to the top surface of the refractory mortar 13 and the inner iron plate 21 in parallel at a distance. A porous iron plate 22 fixed at a right angle, and a whole surface refractory mortar 24 and a rear surface refractory mortar 25 which fill both sides of the porous iron plate 22 so as to communicate with each other, and are integrated with the interior iron plate 21. The above-mentioned problems have been solved by forming a composite refractory layer that closely adheres to each other. In addition, specifically, the aperture ratio of the porous iron plate is 5 to 35.
%, Most preferably 20%, to be the best.

Since the triangular ladle according to the present invention has the above-mentioned structure, the molten metal flowing as the triangular ladle tilts,
It flows along the upper surface of the refractory mortar 13 on the tilting bottom surface, reaches the tap hole 2 at the tip, and flows out downward from this corner. At this time, a perforated iron plate 22 is embedded inside the front and rear refractory mortars 24 and 25, which form the front corner where the thermal shock and the dynamic shock are most concentrated, and the front and rear surfaces are connected by filling the perforated iron plate 23. Since the refractory mortar is connected in the state, the interior iron plate 21, the rear refractory mortar 24, the perforated iron plate 22, and the front refractory mortar 25 are integrally adhered to withstand the impact force, and even if there are gaps or cracks somewhere. Even if occurs, the composite refractory layer adhered integrally does not peel off, and the effect of significantly improving durability is exhibited as compared with the conventional case.

[0012]

1 is a cross-sectional view of a tilting bottom surface 1 and a tap hole 2 showing an embodiment of the present invention, and a final mortar finish is the same as that of the prior art shown in FIG. It's hard to tell out. In FIG. 1, the tilting bottom surface 1 is formed by closely accumulating an outer shell iron plate 11, a refractory brick 12, and a refractory mortar 13. The outer shell iron plate 11 is an outer shell that forms the shape of this triangular ladle, and an iron plate or a heat-resistant steel plate having a plate thickness having a sufficiently calculated strength is assembled by welding to form a desired outer shape. A refractory brick 12 is lined inside the outer iron plate 11. In this case, as an example, a rouxite brick whose main material is bilofarite is applied. The main component of bilofarite is SiO ₂ · AlO ₃ system, and the fire resistance is S
Guarantee K34. A refractory mortar 13 is attached to the upper surface of the refractory brick 12. In the case of this embodiment as a refractory mortar, Al ₂ O ₃ is a plastic material obtained by kneading a high alumina ceramic of 80% or more in the form of a clay, to which an appropriate amount of water glass (sodium silicate) is added. Adjust the viscosity so that it is easy to do, and fill the joints of the brick to finish a smooth molten metal passage surface.

The tip side of the tilting bottom surface 1 serves as a tap hole 2. As for the structure of the tap hole 2, an inner iron plate 21 welded and fixed to the outer iron plate 11 in an upright state serves as a starting end. Interior iron plate 2
Reference numeral 1 serves as a stopper for supporting the refractory brick 12 lined on the tilting bottom surface 1 so as not to slip and slide down as the triangular ladle tilts. On the tip side thereof, there are a rear refractory mortar 24 and a front refractory mortar 25 which are integrally adhered to the interior iron plate 21, and the porous iron plate 22 is covered with both the refractory mortar layers.
Is buried. Since the perforated iron plate 22 is provided with the perforations 23, and the refractory mortar material is filled in the perforated holes 23 to connect the layers of both refractory mortars 24 and 25, the three layers including the perforated iron plate 22 are integrally formed. Finished in a structure that joins to form a strong composite refractory layer.

The aperture ratio of the porous iron plate 22 is one of the requirements of the present invention. If the opening ratio is too small, the communication area of the front and rear fire-resistant mortar layers will be too small to exert an integral connecting action, and if it is too large, the strength of the perforated iron plate itself will be too small and the entire tap hole will be lost. Will lose its binding power. In addition, thermal shock is induced by the stress generated by thermal expansion and contraction associated with rapid heating and quenching.Therefore, there is a certain amount of opening from the point of absorbing and relaxing the large difference in thermal expansion coefficient between refractory mortar and iron plate by means of porosity. It can be presumed that maintaining the rate is effective for thermal cracking and peeling off.

Table 1 is a record obtained by the inventor, in order to specify the optimum opening ratio, by changing the opening ratio on the perforated iron plate at various ratios and forming the tap opening of an actual triangular ladle. As can be seen from the table, if a steel sheet that does not perforate at all is applied, a large difference in the coefficient of thermal expansion between iron and refractory mortar will appear, a thermal shock will be directly hit, and flaking of the refractory mortar will promptly start, similar to the conventional technology. I could only finish, but the aperture ratio was 5
%, The average number of times of use has tripled, and the highest is 1 at 20%.
Recorded 0 times. Considering the fact that the average number of times of use is gradually reduced with this peak as a peak and the increase in the work load accompanying the increase in drilling is taken into consideration, it is practically preferable to specify 35% as the upper limit.

[0016]

[Table 1]

FIG. 2 is a partial sectional view showing the procedure for manufacturing the triangular ladle according to the present invention. The internal size of the triangular ladle applied here is a sector shape having a width of 180 mm and a circular cross section with a radius of 550 mm × 60 degrees, and can accommodate a maximum of 150 kg of molten metal. FIG. 1A shows a state in which the tap hole 2 on the tip side of the tilting bottom surface 1 is being formed, and the rear surface refractory mortar 24 is attached to the interior iron plate 21 in a large amount so as to slightly overflow. In the figure (B), the rear refractory mortar 24 is in a plastic state and is 170 mm wide by 90 mm long and 4 m thick.
A perforated iron plate 22 having a large number of circular holes with a diameter of 5 mm so as to have an opening ratio of 20% is pressed against a steel plate of m, and a part of the rear refractory mortar is squeezed out from the perforations 23 and squeezes out to the front face of the plate. Shows the state of pressing until reaching. In this state, the excess refractory mortar that has leached out is wiped off, and the bottom surface of the perforated iron plate that has been erected vertically to the upper surface of the outer shell iron plate 11 is fillet welded to fix both iron plates. FIG. 6C shows that the front side refractory mortar 25 is more quickly attached to the side surface (the tip side) of the adhered perforated iron plate 22 to enclose the perforated iron plate 22 and the rear side refractory mortar 24 that fills the inside of the perforations 23 first. It shows a state in which the composite composite fireproof layer is completed by communicating with each other.

[0018]

As described above, the present invention has the effect of significantly improving the service life of the triangular ladle often used in the centrifugal casting method. Especially for cast steel and special cast steel, the melt temperature is 1700 ℃
When it is used at a temperature as high as 10 ° C, the service limit of the hot water outlet where the damage is severely concentrated is extended, and in the past, maintenance work, which was forced to perform large and small repairs every time it was used, was carried out almost every time. Significantly reduced to record the number of times of service, which greatly contributed to improvement of workability and release from work under adverse conditions.
It brings a very significant improvement effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part illustrating an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a procedure for carrying out the present invention by (A) to (C).

FIG. 3 is a perspective view of the entire triangular ladle for centrifugal casting.

4 is a sectional view taken along line XX of FIG.

FIG. 5 is a sectional view of a main part of a conventional triangular ladle.

[Explanation of symbols]

1 Tilt bottom 2 tap 10 triangular ladle 11 Outer iron plate 12 refractory bricks 13 Fireproof mortar 21 Interior iron plate 22 Perforated iron plate 23 Porous 24 Rear refractory mortar 25 Front refractory mortar

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[Procedure amendment]

[Submission date] December 27, 2001 (2001.12.
27)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

In a triangular ladle for centrifugal casting according to the present invention, a tilting bottom surface 1 which is one side of a fan-shaped cross section is formed by accumulating an outer shell iron plate 11, a refractory brick 12 and a refractory mortar 13. The tap hole 2 which is the tip of the tilting bottom surface 1 is placed on the outer iron plate 11 in parallel with the inner iron plate 21 standing up to the top surface of the refractory mortar 13 and the inner iron plate 21 in parallel at a distance. a porous iron 22 which is fixed at a right angle, the front refractory mortar 25 encapsulating both sides of the iron plate while communicating by filling a porous 23 bored in the porous iron plate 22, integral with the interior steel plate 21 by the rear refractory mortar 24 The above-mentioned problems have been solved by forming a composite refractory layer that closely adheres to each other. In addition, specifically, the aperture ratio of the porous iron plate is 5 to 35.
%, Most preferably 20%, to be the best.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Since the triangular ladle according to the present invention has the above-mentioned structure, the molten metal flowing as the triangular ladle tilts,
It flows along the upper surface of the refractory mortar 13 on the tilting bottom surface, reaches the tap hole 2 at the tip, and flows out downward from this corner. At this time, a perforated iron plate 22 is embedded inside the front and rear refractory mortars 25 and 24 , which construct the front corners where the thermal shock and the dynamic shock are most concentrated, and the perforated iron plates 22 are filled so that the front and rear surfaces communicate with each other. Since the refractory mortar is connected in the state, the interior iron plate 21, the rear refractory mortar 24, the perforated iron plate 22, and the front refractory mortar 25 are integrally adhered to withstand the impact force, and even if there are gaps or cracks somewhere. Even if occurs, the composite refractory layer adhered integrally does not peel off, and the effect of significantly improving durability is exhibited as compared with the conventional case.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

FIG. 5 is a cross-sectional view illustrating the principle of the centrifugal casting method.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroaki Maeda             1-12-19 Kitahori, Nishi-ku, Osaka City Stock Association             Kurimoto Ironworks (72) Inventor Masaaki Yamamoto             1-12-19 Kitahori, Nishi-ku, Osaka City Stock Association             Kurimoto Ironworks F-term (reference) 4E014 BA02 BB02 BC01

Claims (2)

[Claims] 1. In a triangular ladle for centrifugal casting, a tilting bottom surface 1 which is one side of a fan-shaped cross section is formed by accumulating an outer shell iron plate 11, a refractory brick 12 and a refractory mortar 13, and at the tip of the tilting bottom surface 1. A certain outlet 2 is an inner iron plate 21 standing upright on the outer iron plate 11 up to the top surface of the refractory mortar 13, and a perforated iron plate 22 fixed to the outer iron plate 11 at a right angle in parallel with the inner iron plate 21 at a distance. , A composite refractory layer that is integrally adhered to the interior iron plate 21 by a front refractory mortar 24 and a rear surface refractory mortar 25 that fill and communicate with the perforated holes 23 formed in the perforated iron plate 22 so as to cover both sides of the iron plate. A triangular ladle for centrifugal casting characterized by being formed. 2. The triangular ladle for centrifugal casting according to claim 1, wherein the porous iron plate 22 has an opening ratio of 5 to 35%.