JPS59130674A - Bottom running ingot making method - Google Patents

Abstract

PURPOSE:To act effectively covering materials and to obtain defectless casting in a bottom running ingot making method by setting preliminarily powder covering agents and a plate-shaped covering material for a molten metal in a casting mold. CONSTITUTION:A plate-shaped covering material for a molten metal consisting of an inside layer 3 of the plate-shaped covering material for the molten metal and a surface coating layer 12 of the plate-shaped covering material for the molten metal is suspended from the upper part of a riser flask 1 by means of a rope 11 in the casting mold 2 on a molding board 5. A powder covering agent 4 is put in a bag 13 and plural pieces of such bags are suspended from the plate- shaped covering material for the molten metal by means of ropes 11. A molten metal 8 is thereupon charged from the charging port 10 in the bottom of a ladle 9 through a charging pipe 7 and a runner 6 into the mold 2. As a result, the sepn. of the casting mold and the molten metal is made easy and since the powder covering agents are interposed, the oxidation of the surface of the molten metal is prevented.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a bottom pouring ingot making method, and particularly to a bottom pouring ingot casting method in which molten metal in a ladle is bottom poured into a mold set on a surface plate. It is about law.

[Prior art]

In the conventional bottom pouring ingot method, a so-called cast ingot method is known in which a coating agent is used for the purpose of preventing oxidation of the molten metal in the mold and improving the casting surface. In the conventional molding method, a method using a powder coating agent (for example, Japanese Patent Application Laid-Open No. 52-15162
7), and recently there is a method using a multilayer plate-like coating (for example, Japanese Patent Publication No. 15991/1983). In the method of using a powder coating agent, the powder coating agent also rises as the molten metal level rises after pouring, making it difficult to uniformly interpose it between the mold and the molten metal, making it difficult to maintain a clean casting surface. difficult to obtain. In addition, the powder coating material is unevenly distributed in the upper part of the molten metal in the periphery where it comes into contact with the mold, and the center of the surface of the molten metal is exposed and oxidized.

Although the method using a multilayer plate-like coating material is effective in preventing oxidation of the molten metal surface, it is not possible to obtain a clean casting surface. Furthermore, it is said that it becomes powdered when it comes into contact with the molten metal, and that a clean casting surface can be achieved by interposing the powder between the mold and the molten metal, but it is difficult to supply enough powder to improve the casting surface.

[Purpose of the invention]

The purpose of the present invention was to overcome the above-mentioned problems associated with the bottom casting method using a coating material. Our goal is to provide an ingot making method.

[Summary of the invention]

The key point of the present invention is that a powder coating material and a plate-shaped molten metal coating material are set in advance in a mold in the bottom pouring ingot method.

According to the present invention, ingot formation in the mold is carried out using a plate-shaped molten metal covering material suspended at a predetermined distance within the mold and a powdered covering material placed below the plate-shaped molten metal covering material. is interposed between the mold and the molten metal while being pressed against the plate-shaped molten metal covering material and partially in a molten state. As a result, the mold and molten metal can be easily separated. In addition, the exposed parts of the molten metal surface caused by the interposition of the powder coating material between the mold and the bath water remain covered with the plate-shaped molten metal coating material, which has the effect of preventing oxidation of the molten metal surface. . In addition, powdered coating materials and plate-shaped molten metal cladding materials absorb inclusions on the surface of the molten metal,
It has the effect of catching clean fish.

In the present invention, the powder coating is placed in a bag.

It is effective to suspend a plurality of pieces from a plate-shaped molten metal covering material and position them around the inside of the mold. By placing the molten metal in a bag, the bag breaks as the molten metal rises, and the powdered coating material that comes into contact with the molten metal melts little by little, minimizing the amount of powdered coating material that gets caught inside the molten metal. . By suspending a plurality of bags containing the powder coating material, the powder coating material can be uniformly interposed over a wide range between the mold and the molten metal.

The suspension position of the plate-shaped molten metal coating material is as follows: @If the mold height is h,
The distance between the surface plate and the top surface of the plate-shaped bath water covering material is (1/3) h ~
(1/2) h, and it is desirable that the lower end of the bag containing the powdered coating material suspended on the plate-shaped molten metal coating material be away from the surface plate. If the suspended bag containing the powdered coating material is separated from the surface plate, the powdered coating material will be drawn into the molten metal immediately after it is poured into the mold, contaminating the internal steel. The ingredients of the powder coating agent that prevents this are 5i02.
Cab.

B2O5, Cab'2. Preferably, Na2COs and CO are used. CaF2 has the effect of promoting slag formation, and B20. s N B2 COs and 2CO1HfM
Base! , 2 to 5% each to adjust the softening point and melting point.
It is effective to add

The structure of the plate-shaped molten metal coating material consists of an internal layer and a surface coating layer. This has a smaller specific gravity than the molten metal, and is able to maintain its external shape while floating on the surface of the molten metal. The components of the inner layer are 5i02. At20s, Ca
The reason why b, CaF, is made of an inorganic compound and fibrous material is that it is easy to mold, and even if the surface coating layer is destroyed, the inner layer components are the same as those of the powder coating. This is because it can become one with the

The shape of the plate-shaped molten metal coating material is preferably a disk shape with a thickness of 50 to 150 m. If the thickness is less than 50 mm, it is difficult to mold the inner layer and the strength is insufficient.

Since the cross section of the mold is polygonal, a circular shape without corners is effective for the plate-shaped molten metal covering material to rise smoothly as the molten metal surface rises. The diameter of the disk should be at least 70 to 8 times the inner diameter of the mold to prevent the powder coating material from overflowing onto the upper surface of the plate-shaped molten metal coating material from the gap between the plate-shaped molten metal coating material and the inner periphery of the mold.
It is necessary to have a size of 0%. The thickness of the surface coating layer of the plate-shaped molten metal coating material is suitably between 2 and 5 mm in order to maintain strength.

The attached figures will be explained below. FIG. 1 shows the installation of a plate-shaped molten metal coating material and a powder coating material in a mold before the molten metal is undercast into the mold. In FIG. 1, refined molten metal 8 is poured through a pouring spout 10 at the bottom of a ladle 9, a pouring pipe 7, and a runner 6 into a mold 2 with a riser frame 1 placed on top. The mold 2 is placed on a surface plate 5. Inside the #J type 2 before pouring, a plate-shaped molten metal coating material consisting of an inner layer 3 of the plate-shaped molten metal coating material and a surface coating layer 12 of the plate-shaped molten metal coating material is suspended from the top of the feeder frame 1 by a suspension rope 11. This is a pull-up. In addition, powder coating rice powder 4 is in bag 1.
3, and the plurality of bags are suspended from the plate-shaped molten metal covering material by a suspension rope 11.

FIG. 2 shows that molten metal 8 is poured into the mold 2, and a powder coating material 4 is poured into the mold 2.
This figure shows the state in which the metal is interposed between the mold 2 and the molten metal 8 after melting. This figure shows a state in which the surface coating layer 12 of the plate-shaped molten metal coating covers the grooves and the surface of the molten metal during molding.

[Embodiments of the invention]

Next, the present invention will be specifically explained based on one embodiment. After rough refining (melting and some oxidation refining) ordinary carbon steel of material S and QC in an electric furnace, approximately 155
The steel was tapped into a ladle at a temperature of . Final refining and composition adjustment were performed in a ladle refining furnace and the steel was tapped into a ladle. The molten metal in the ladle is about 1
5707: Molten metal was poured into the mold. The investigation was conducted by comparing a conventional agglomeration method using a powder coating agent and an agglomeration method using a combination of the powder coating agent and plate-shaped molten metal coating material of the present invention.

In the conventional agglomeration method using a powder coating agent, the powder coating agent (6
One bag containing 0 to 9) was suspended using a hanging rope so that the leakage of the bag was at a height of about 500 cm from the surface plate.

In addition, in the agglomeration method of the present invention, the inner layer of the plate-shaped molten metal coating material is
o26o%, At, 0.20%.

Add 101 nt of gum arabic aqueous solution to 50 g of well-mixed powder of each inorganic compound powder at a ratio of 10% C20, 10% CaF, and add fibrous glass whirl and mat while kneading, and compression mold it into a disk shape. It was dried at 100C for 5 hours. The surface coating layer of the plate-like molten metal coating material was obtained by impregnating the surface of the dried disk with colloidal silica, coating alumina powder thereon, and repeating this process several times to obtain a thickness of about 5 gourds.

From this plate-shaped molten metal coating material, the powder coating material (
Two bags containing 50 Kr) were suspended, and a plate-shaped molten metal covering material was further suspended in the mold using a suspension rope. The bag containing the powdered coating material was placed so that its bottom end was 50 mm above the surface plate. The composition of the powder coating is, for example, 5iO250%, Ca
O10%, B20゜20%1CaF210%, Na2
A mixed melt of inorganic compounds containing 5% Co and 35% CO is crushed to produce powder with a particle size of 100 mesh or less.
0%, 20% and 50 particles of 50-100 mesh
Graphite powder is added in a weight ratio of 10 to 9 parts of powder to a powder containing 20% of coarse particles of mesh size or larger. The size of the mold is 2000 mm in height, the cross-sectional shape is hexagonal, the length of the diagonal is 600 mm, and the length of the riser frame is 500 mm. The rising speed of the molten metal in the mold is 2
00 to 250m/-.

The survey results are shown in Table 1.

Table 1 The survey methods and results for the survey items in Table 1 are explained below. The coverage rate is determined by observing the steel ingot pulled out of the mold after the molten metal has solidified, and calculating the ratio of the coating area on the surface of the steel ingot in contact with the inner periphery of the mold wall to the total surface area, and It represents the ratio of the contact area of the coating material and the forest-like coating material to the total area of the upper part of the steel ingot. In the conventional ingot-forming method, a powder coating agent is used at a ratio of about 2 to 7 parts per steel ingot, but the coverage of the inner periphery of the mold wall is extremely low at 10%. On the other hand, in the ingot-forming method of the present invention, the amount of powdered coating material used is increased by about 1.5 times compared to the conventional method, and as a result of suspending the powder coating material in multiple pieces, The coating condition has been significantly improved, and the coating is uniform, with a coverage rate of 85%.
It turned out to be a matter of luck. The coverage of the upper surface of the bathtub was also approximately 100% due to the effect of using the plate-shaped bathtub coating material.

In addition, the heat retention efficiency has improved with the improved coverage of the molten metal surface by the plate-shaped molten metal coating material, and the shrinkage pores in the riser area have been reduced compared to the conventional method, and the billet yield has been reduced to 68% compared to the conventional method.
This has increased from 87% to 87%. Furthermore, compared to the conventional method, the mold life was reduced to approximately 115 in the method according to the present invention compared to the number of repair points and repair times in the conventional method. Therefore, it is estimated that the mold life is approximately 500 times in the method according to the present invention, compared to approximately 100 times in the conventional method. This is the value.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the molten metal before pouring in an embodiment of the bottom pouring method of the present invention, and Figure 2 is a plate-shaped molten metal after pouring bath metal into the mold from the condition shown in Figure 1. FIG. 2 is a schematic cross-sectional view showing the state of contact between the coating material and the powdered coating material, the bath water, the mold, and the like. 2...Mold, 3...Inner layer of plate-shaped molten metal coating material, 4...
・Powdered disrupting agent, 5...surface plate, 8...bath water, 9...
・Ladle, 12 hangings 1 figure 428- Funeral figure 2

Claims (1)

[Claims] 1. In a method of bottom pouring and casting molten metal from a ladle into a mold set on a surface plate, a plate-shaped molten metal coating material and a powder coating material are installed in the mold, and the powder coating material is placed in the mold. A bottom pouring agglomeration method, characterized in that the agent is placed under the plate-shaped molten metal coating material and agglomeration is performed.