JP3188195B2 - Vacuum casting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum casting apparatus used for vacuum casting of degassed steel or the like refined in a vacuum degassing furnace.

[0002]

2. Description of the Related Art In some cases, individual cast steel products requiring high quality, such as turbine casings, are manufactured using degassed steel. In general refining of degassed steel used for such individual cast steel products, a steel of a specific material is melted in an arc furnace, and then a twinkle-type arc heater called a vacuum degassing furnace is used. Harmful nitrogen, oxygen and hydrogen contained in the molten steel are desorbed by the ladle refining method to reduce their contents. The ladle used in this ladle scouring method is a ladle with a slide gate that can be scoured in a vacuum degassing furnace, and operates the slide gate provided at the lower end of the ladle in the atmosphere. It is made to pour directly from the ladle into the mold of the individual cast steel product.

A typical example of a conventional apparatus for pouring degassed steel into a mold, which is used for producing such an individual cast steel product, will be described with reference to FIGS.
FIG. 4 is a cross-sectional view showing a state before air casting is performed using a ladle with a slide gate. In this figure, molten steel 0 which has been scoured and degassed in a vacuum degassing furnace (not shown) is shown.
The ladle 02 with the slide gate 03 accommodating the ladle 4 is lifted by an overhead crane (not shown) and moved to above the mold 01 in which a space 05 for forming an individual cast steel product is provided. And a slide gate 03 provided at the lower part of the ladle 02 is shown above the gate 06 communicating with the space 05.

FIG. 5 is a detailed cross-sectional view around a pouring section in section B of FIG. As shown in the figure, the slide gate 03 positioned above the gate 06 becomes one body with the lower nozzle 031, the nozzle holder 032, the lower nozzle 031, and the nozzle holder 032 from below, and the lower end of the ladle 02 is moved right and left. The upper plate 034 fixed to the lower end of the upper nozzle 021, and the lower plate 033 and the upper plate 034 are provided with a hole concentric with the passage of the upper nozzle 021 fixed to the lower end of the ladle 02. Are pierced respectively,
It comprises a gas channel 035 for blowing argon gas 07.

[0005] From the gas channel 035, the molten steel 04 flowing into the above-described upper nozzle 021 is supplied.
Argon gas 07 supplied from outside via a supply pipe is blown into the upper nozzle 021 so that the molten steel 04 does not flow into the upper nozzle 021 so as not to be solidified in the inside 1. Further, the ladle 02 is provided with a sprue 06 opening at the axis of the upper nozzle 021 provided at the lower end and the upper end of the mold 01.
Is finely adjusted by an overhead crane to a position substantially coincident with the axis of.

FIG. 6 is a detailed sectional view showing a molten metal 04 in a ladle 02 being poured into a casting mold. As shown in the figure, the lower plate 033 is integrated with the lower nozzle 031 and the nozzle holder 032, and by sliding the lower end of the ladle 02 in the horizontal direction, the lower end opening of the lower nozzle 031 is positioned directly above the gate 06. At the same time, by being arranged concentrically with the upper nozzle 021, the argon gas 07 supplied from the gas channel 035 and preventing the molten steel 04 from flowing into the upper nozzle 021 is discharged from the lower end opening of the lower nozzle 031. Then, the molten steel 04 in the ladle 02 passes through the upper nozzle 021, the upper plate 034, the lower plate 033, and the lower nozzle 031, and is poured into the mold 01 from the sprue 06.

In a conventional degassing steel casting apparatus as shown in FIGS. 4 to 6, when pouring as shown in FIG. 6, the lower nozzle 031 at the position shown in FIG. 5 is slid rightward. Therefore, it is necessary to provide a space for this slide between the lower end of the lower nozzle 031 and the upper end of the gate 06.

For this purpose, degassed molten steel 04 in a ladle 02 which is scoured in a vacuum degassing furnace and injected into a mold 01
During pouring, the molten steel 04 that flows out of the lower nozzle 031 and flows into the gate 06 while being in contact with the atmosphere between the lower nozzle 031 and the gate 06 at the time of pouring involves a certain amount of surrounding air. Also, at the stage where molten steel 04 flows from the sprue 06 and passes through the runner to fill the space 05 in the mold 01 with the molten steel 04, the molten steel 04 comes into contact with the atmosphere again, and
Due to the heating of the mold 01, the gas 08 generated from the mold 01 may enter the molten steel 04.

As described above, the conventional molten steel 04 (degassed steel) refined by the ladle 01 with the slide gate 03 capable of being refined in the vacuum degassing furnace is cast into the individual cast steel product mold 01 by: Molten steel which is refined in a vacuum degassing furnace and degass harmful nitrogen, oxygen and hydrogen contained in the molten steel to reduce its content.
Sample No. 4 contained these harmful gases due to contact with the atmosphere, and reduced the quality value of the individual cast steel product. The gas 08 generated from the mold 01 is
4, the steel product sometimes had an individual casting with a casting defect.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides a method for casting molten steel in a ladle with a slide gate, which had to be cast in the atmosphere conventionally, into a mold without contact with the atmosphere. A high-quality cast steel product that eliminates the problems caused by contact of molten steel refined in a vacuum degassing furnace with the air or the problems caused by the gas generated from a mold penetrating into molten steel caused by the above-described atmospheric casting. It is an object of the present invention to provide a vacuum casting apparatus which can be used.

[0011]

Therefore, the vacuum casting apparatus of the present invention has the following means.

(1) An exhaust port for vacuum suction for discharging air inside, an air introduction valve for introducing air for injecting air into the inside, and a peripheral edge of an upper opening opening upward. , the vacuum chamber which is disposed a gasket for retaining the vacuum, as well as vacuum window for viewing the interior of the casting conditions, with a pouring port for pouring molten steel is provided inside the peripheral portion of the pouring port And an upper lid provided with a pouring port flange which is in close contact with and joined to a vacuum gasket disposed at A vacuum vessel was provided in which a mold for filling a molten steel injected from a gate to form a cast steel product was installed.

(2) The lower surface of the flange protruding from the outer peripheral edge of the upper end portion and the upper surface of the flange provided on the outer peripheral edge of the pouring port are closely adhered and joined via a vacuum gasket, and are shielded by the opening opening at the upper end. Provided through a seal , pouring
A vacuum shielding plate which melts by heat was laminated, and a pouring nozzle was provided which was suspended from the pouring port into the vacuum vessel in order to close the upper end opening until pouring.

(3) Placed concentrically with the pouring nozzle on a vacuum shield plate closing the upper opening of the pouring nozzle via a fireproof seal having an opening concentric with the upper opening of the pouring nozzle. The lower nozzle is provided between the lower nozzle and the upper nozzle concentrically disposed at the lower end of the ladle containing the pouring water, and is slid left and right to open the lower end of the upper nozzle. Then, the upper nozzle and the lower nozzle are communicated or closed to shut off the communication between the upper nozzle and the lower nozzle, and the molten metal in the ladle is passed through the upper nozzle, the lower nozzle and the pouring nozzle,
A slide gate for pouring a predetermined amount of molten metal into a mold set in a vacuum vessel was provided.

The slide gate has a hole provided at the lower end of the conventional ladle and concentric with the passage of the upper nozzle.
In addition to the upper plate fixed to the lower end of the ladle, a hole concentric with the passage of the lower nozzle is provided, and the lower plate fixed to the upper end of the lower nozzle and the left and right slide between the upper plate and the lower plate Then, a middle plate provided with holes communicating with the holes provided in the upper plate and the lower plate is provided, and the lower end of the upper plate arranged concentrically with the lower nozzle by sliding the middle plate in the left-right direction. It is desirable that the configuration be open. In addition, it is desirable that a lower end of the lower nozzle can be placed on the upper surface of the fireproof seal on the outer periphery of the lower nozzle, and a nozzle holder that stably supports the lower nozzle on the fireproof seal is fixedly provided.

According to the vacuum casting apparatus of the present invention, molten steel in a ladle with a slide gate, which can be scoured in a vacuum degassing furnace, is scoured in the vacuum degassing furnace. The harmful nitrogen, oxygen and hydrogen contained in the molten steel are degassed, and the molten steel whose content has been reduced is poured into a mold installed in a vacuum vessel without contacting the atmosphere. Also, the surrounding air does not get into the molten steel during the pouring. Also, during pouring, the mold is heated by the high-temperature molten steel, and the gas generated from the mold is immediately exhausted from the inside of the vacuum vessel to the outside, and the inside of the mold is filled with molten steel into which the gas generated from the mold does not enter. You. This makes it possible to produce a cast steel product of high quality molten steel having no casting defects and sufficiently reducing the gas contained in the cast steel.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vacuum casting apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall sectional view showing a first embodiment of the vacuum casting apparatus of the present invention,
FIG. 2 is a detailed sectional view showing the part A shown in FIG. 1 before casting, and FIG. 3 is a detailed sectional view showing the part A shown in FIG. 1 during casting.

As shown in FIG. 1, a vacuum chamber 11 in which a mold 13 is installed is provided with an exhaust port 111 for vacuum suction for discharging air inside the side wall, and a manufactured cast steel product is taken out. When the air introduction valve 11 for injecting air into the inside
A gasket 113 for maintaining the vacuum is provided at the upper end of the side wall at the periphery of the upper opening, while the inside can be freely formed into a vacuum state and an atmospheric state.

In addition to the vacuum vessel 2, the upper lid 12 forming the vacuum vessel 1 has a vacuum window 121 at the upper end for visually recognizing the inside of the vacuum vessel 11, and a mold 13 installed in the vacuum vessel 2. A pouring port 122 for injecting the gasket 3 is provided, and an outer lid flange 123 for pressing and sealing a gasket 113 provided in the vacuum chamber 11 on the lower surface thereof is provided on the outer periphery.

Further, a mold space 131 for forming a cast steel product with the molten steel 3 to be filled is formed in the mold 13 disposed inside the vacuum chamber 11, and a mold space 131 is formed between the mold space 131 and a runner 132. A spout 133 is provided which is communicated with and opens below the pouring spout 122 of the upper lid 12. Also, the mold space 131
Above is provided a feeder portion 134 opened into the vacuum vessel 1. The ladle 2 containing the molten steel 3 degassed in a vacuum degassing furnace (not shown) is set on the upper lid 12 of the vacuum vessel 1 configured as described above, and is placed in a preparation state before the start of casting. You.

Under such circumstances, the interior of the vacuum vessel 1 is evacuated by a vacuum pump communicating with the exhaust port 111 to start casting. That is, the degassed molten steel 3 in the ladle 2 is passed through a slide gate 4 to be described later and a pouring nozzle 5 to be described below, which is suspended from a pouring port 122, from a pouring port 133 of the mold 13 to a runner 132 Is poured into the mold space 131 through the mold. At this time, the feeder portion 134 of the mold 13 is
By observing this, it is possible to confirm the rising state of the molten metal level in the mold space 135 and the pouring stop time. The combustion gas 135 generated from the mold 13 by the pouring heat is supplied to the vacuum vessel 1.
It diffuses in and is exhausted to the outside through the exhaust port 111.

Next, an apparatus for pouring the degassed molten steel 3 in the ladle 2 into the mold 13 without contacting the atmosphere and entraining surrounding air is shown in FIGS. 3
It will be explained based on the following.

The pouring port 122 provided on the above-mentioned upper lid 12 is provided with a pouring port flange 124 projecting upward, and a vacuum gasket 12 is provided on the upper surface of the pouring port flange 124.
5 are provided. Pouring port 122 configured in this way
The cylindrical pouring nozzle 5 is concentrically arranged with the pouring port 122 so as to press the vacuum gasket 125 on the lower surface of the vacuum flange 51 provided so as to protrude from the upper end in the radial direction. Have been. A replaceable refractory sleeve 52 is fitted on the inner peripheral surface of the pouring nozzle 5, and a vacuum shield plate 54 is provided at the upper end opening thereof via a shield seal 53 on the upper surface of the vacuum flange 51. It is provided and closed except when pouring.

The vacuum shield plate 54 is made of a material that withstands the vacuum pressure generated in the vacuum vessel 1 and that is instantaneously melted by the heat of the molten steel 3 at the start of pouring. When the inner diameter is 120 mm, an aluminum plate having a thickness of about 2 mm is effective. That is, until the pouring port 122 starts the casting, as shown in FIG.
The interior of the vacuum vessel 1 can be maintained at a high vacuum because it is completely sealed by the pouring nozzle 5 provided with 4.

On the upper surface of the vacuum shielding plate 54, a fireproof seal 55 having a hole concentric with the pouring nozzle 5 is provided. This refractory seal 55 is used for the molten steel 3 during pouring.
Even if the outer peripheral portion of the vacuum shielding plate 64 is melted by the heat of
Is preferably made of a plastic refractory material having plasticity.

Next, the slide gate 4 provided between the upper nozzle 21 provided at the lower end of the ladle 2 and the above-described pouring nozzle 5 will be described. The slide gate 4
A nozzle holder 42 is provided on the outer periphery and is concentric with the upper nozzle 21, and the lower nozzle 41 and the lower nozzle which are placed concentrically with the pouring nozzle 5 on the refractory seal 55 of the pouring nozzle 5. The projection on the bottom surface is fitted to the upper end of the lower nozzle 41 and the lower nozzle 4
A lower plate 43 having a hole concentric with 1, an upper plate 44 fixed to the lower surface of the upper nozzle 21 and having a hole concentric with the upper nozzle 21, and a portion between the lower plate 43 and the upper plate 44. Slides right and left through the gap 46 formed in the upper nozzle 21 and the lower nozzle 41,
It comprises a middle plate 45 with a hole communicating the upper nozzle 21 and the lower nozzle 41.

As described above, the slide gate 4 is of a three-plate type in which the upper plate 44, the middle plate 45, and the lower plate 43 are provided.
The slide gate 4 utilizes an existing product of the lower nozzle 031 fixed type lower plate 033, which is applied to the adjustment of the amount of ladle hot water in continuous casting, as the lower nozzle 41 and the lower plate 43, and makes use of the advantage of fixing. As described above, a flange portion is provided at the lower end of the nozzle holder 42 and the fireproof seal 5 is provided.
It can be set to 5.

An upper nozzle 2 provided at the bottom of the ladle 2
In the upper plate 44 and the middle plate 48, a gas passage 47 for blowing the argon gas 6 into the upper nozzle 21 is formed in the upper plate 44 and the middle plate 48 so that the molten steel 3 does not solidify. A gas channel 48 is provided toward the inside of the nozzle 21. Then, the argon gas 6 supplied from the outside is blown into the upper nozzle 21 from the gas channel 48 through the gas passage 47, and the molten steel 3 flows into the upper nozzle 21 before pouring as shown in FIG. And solidification of the molten steel 3 in the upper nozzle 21 is prevented.

When the middle plate 45 is slid rightward from the state before pouring shown in FIG. 2 so that the position of the hole formed in the middle plate 45 matches the position of the hole formed in the upper nozzle 21, at the same time, The hole of the middle plate 45 is the lower plate 4
3, the positions of the holes of the lower nozzle 41 also match, and the upper nozzle 21
The pressure of the argon gas 6 injected therein suddenly decreases, and the molten steel 3 in the ladle 2 flows into the lower end of the lower nozzle 41. Due to the inflow of the molten steel 3, the vacuum shielding plate 54 closing the upper end of the pouring nozzle 5 is instantaneously melted.
As shown in the figure, the molten metal is poured into the pouring gate 133 located below the inside of the refractory sleeve 52 of the pouring nozzle 5, and is filled into the mold space 131 through the runner 132.

As described above, the molten steel 3 refined in the ladle 2 with the slide gate 4 capable of degassing and scouring in the vacuum degassing furnace flows out of the upper nozzle 21 provided at the lower end of the ladle 2. Until the molten metal is poured into the mold 13 to form a cast steel product, it does not come into contact with the air at all, and does not entrain the surrounding air in the middle of flowing into the mold 13, and contains the refined gas. The amount is kept as is. Further, the combustion gas 135 generated from the casting mold 13 by the injection of the molten steel 3 is also quickly discharged from the inside of the vacuum vessel 1 to the outside, so that these combustion gases do not melt into the molten steel 3.

Next, a cast steel product having a unit weight of 5.6 ton (turbine casing, material; manufactured by using the vacuum casting apparatus of the present embodiment and the arc furnace and the vacuum degassing furnace owned by the present applicant). SCPH-21 ... CrMo steel, mold; alkali phenol sand) (3) and gas concentration when atmospheric furnace steel melted in an arc furnace is cast in the atmosphere (1),
Table 1 shows the gas concentrations (2) in the case where degassed steel obtained by refining atmospheric furnace steel in a vacuum degassing furnace was cast in the atmosphere.

As described above, the cast steel product manufactured by the vacuum casting apparatus according to the present embodiment can be of high quality in which harmful nitrogen, oxygen and hydrogen are reduced in quantity without impairing the quality. In addition, casting defects can be eliminated.

[0033]

[Table 1]

[0034]

As described above, according to the vacuum casting apparatus of the present invention, according to the structure shown in the claims, the vacuum casting apparatus in the ladle with the slide gate capable of scouring in the vacuum degassing furnace is provided. The gas steel is poured into the mold without coming into contact with the atmosphere.During the pouring, the gas generated from the mold is diffused and exhausted into the vacuum chamber, and degassed high-quality molten steel is placed inside the mold. Filled, high quality cast steel products can be manufactured.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing a state before casting using a vacuum casting apparatus as a first embodiment of the present invention,

FIG. 2 is a partial cross-sectional view showing details around a pouring portion before casting in a portion A shown in FIG. 1,

FIG. 3 is a partial cross-sectional view showing details around a pouring portion during casting in a portion A shown in FIG. 1,

FIG. 4 is an overall sectional view showing a state before casting of degassed steel into a conventional individual cast steel mold,

FIG. 5 is a partial cross-sectional view showing details around a pouring portion before casting in a portion B shown in FIG. 4,

FIG. 6 is a partial cross-sectional view showing details around a pouring portion during casting in a portion B shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 11 Vacuum tank 111 Exhaust port 112 Air introduction valve 113 Gasket 12 Top lid 121 Vacuum window 122 Filling port 123 Top lid flange 124 Filling port flange 125 Vacuum gasket 13,01 Mold 131,05 Mold space 132 Runner 133,06 Gate 134 Feeder 135,08 Combustion gas 2,02 Ladle 21,021 Upper nozzle 3,04 Molten steel 4,03 Slide gate 41,031 Lower nozzle 42,032 Nozzle holder 43,033 Lower plate 44,034 Upper plate 45 Medium plate 46 gap 47 gas passage 48,035 gas channel 5 pouring nozzle 51 vacuum flange 52 fireproof sleeve 53 shielding seal 54 vacuum shielding plate 55 fireproof seal 6,07 argon gas

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-122060 (JP, A) JP-A-9-201665 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 18/06 B22D 1/00

Claims (1)

(57) [Claims] 1. A vacuum vessel having an exhaust port for vacuum suction, an air introduction valve for introducing air, and a gasket disposed on a periphery of an upper opening, a vacuum window, a pouring port, and a periphery of the pouring port. A vacuum vessel comprising a top lid provided with a spout flange for sealing by joining with a vacuum gasket disposed in the section, and a space provided therein with a space for installing a mold connected to the pouring port, and via the vacuum gasket. A vacuum flange is provided on the outer periphery of the upper end for sealing by joining, and the upper end opening is closed by a vacuum shielding plate provided by a shielding seal and melted by pouring heat, and is vertically suspended from the pouring opening into the vacuum container. Pouring nozzle and a lower nozzle disposed concentrically with an upper nozzle disposed at the lower end of a ladle containing the molten metal and concentrically mounted on the vacuum shielding plate via a fireproof seal. The upper nozzle and the lower nozzle And a slide gate for pouring the molten metal into the mold via the lower nozzle and the pouring nozzle by opening and closing the lower end of the upper nozzle laterally between the mold and the casting nozzle. Vacuum casting equipment.