JP2023025999A - metal casting method - Google Patents

Abstract

To provide a metal casting method capable of preventing a molten metal at the inside of a fire-resistant pipe filled and erected in a mold for molten metal feed from flowing to an outer circumferential side of the fire-resistant pipe.SOLUTION: Provided is a metal casting method where a fire-resistant pipe 10 is erected in such a manner that a lower side part thereof is filled into a mold 20 and an internal space 13 thereof is communicated with a cavity 23 of the mold 20, an induction coil 40 is freely fitted to an outer circumferential side of an upper side part not filled into the mold 20 of the fire-resistant pipe 10, a metal M is poured into the cavity 23 of the mold 20 and the fire-resistant pipe 10, and the metal M poured into the fire-resistant pipe 10 is induction-heated and the molten state is maintained so as to perform molten metal feed, wherein the fire-resistant pipe 10 is made of a tubular part 11 forming the internal space 13, and a flange-like part 16 formed at a lower end of the tubular part 11.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a metal casting method, and more particularly to a casting method suitable for producing castings from high melting temperature metals such as cast steel.

A riser is indispensable for preventing casting defects such as shrinkage cavities in metal casting.
Conventionally, the size of the riser is reduced by induction heating the riser (see Patent Document 1 below).
In addition, as a casting method that can be freely and economically adapted to various shapes and sizes, from small to large quantities, and to a wide range of production forms, at the same time, it communicates with the mold cavity as a casting method that has a remarkable effect in improving the cutting work of the feeder part. An induction coil is loosely fitted to the outside of the refractory pipe that is embedded and erected in the mold so as to The present applicant has proposed a metal casting method for final solidification of molten metal (see Patent Document 2 below).

JP-A-55-64958 JP-A-9-314310

When casting a metal with a high melting temperature such as cast steel by the metal casting method described in Patent Document 2, the temperature of the metal poured into the refractory pipe is increased to about 1500 to 1600 ° C. by induction heating. must be maintained and the refractory pipe will reach a similar temperature. Also, if the refractory pipe is constructed of an inductive heating material, the temperature of the refractory pipe may be higher than the temperature of the molten metal inside.

In such a case, part of the molten metal inside the refractory pipe wraps around the lower end surface of the refractory pipe embedded in the mold, and along the outer peripheral surface of the refractory pipe (interface with the mold, etc.) It may rise and leak out of the mold.
If the molten metal leaking out of the mold comes into contact with the induction coil, there is a risk that the induction coil will be eroded or short-circuited between layers.

The present invention has been made based on the circumstances described above, and its object is to prevent the molten metal inside a refractory pipe embedded and erected in a mold for raising from the outer circumference of the refractory pipe. To provide a metal casting method which does not flow sideways.

(1) In the metal casting method of the present invention, the lower part of the refractory pipe is embedded in the mold, and the refractory pipe is erected so that the internal space of the refractory pipe communicates with the cavity of the mold. , an induction coil is loosely fitted on the outer peripheral side of the upper portion of the refractory pipe that is not embedded in the mold, and metal is poured into the cavity of the mold and the inside of the refractory pipe, and the refractory pipe is In a metal casting method in which a riser is carried out by induction heating the metal poured into the inside of and maintaining the molten state,
The refractory pipe is characterized by comprising a tubular portion forming the internal space and a brim portion formed at the lower end of the tubular portion.

According to such a metal casting method, the molten metal flowing out from the lower end opening of the refractory pipe is cooled on the end surface (lower end surface) of the brim portion and solidifies before reaching the outer peripheral edge of the brim portion. . This can prevent the molten metal inside the refractory pipe from flowing to the outer peripheral side of the refractory pipe (the outer peripheral surface of the tubular portion).

(2) In the metal casting method of the present invention, it is preferable to induction-heat the metal poured into the refractory pipe to 1400° C. or higher.
The use of a refractory pipe with a collar is particularly effective when heating metal inside the refractory pipe at temperatures above 1400°C.

(3) In the metal casting method of (2) above, the metal is preferably cast steel.
When casting cast steel, it is necessary to heat the cast steel inside the refractory pipe to 1500° C. or more, so it is particularly effective to use a refractory pipe with a flange.

(4) In the metal casting method of the present invention, it is preferable that the coefficient of thermal expansion of the constituent material of the refractory pipe is 5.0×10 ^-6 /K or less in the range of 1000 to 1650°C.

(5) In the metal casting method of (4) above, it is preferable that the refractory pipe is made of any one of alumina graphite, zirconia graphite, fused silica, conductive ceramic, and graphite.

(6) In the metal casting method of the present invention, the outer diameter (D ₁₁ ) of the tubular portion is 50 to 400 mm, the outer diameter (D ₁₆ ) of the brim portion is 100 to 800 mm, and the brim portion It is preferable that the width of the flange [W ₁₆ =(D ₁₆ -D ₁₁ )/2] at 10 to 300 mm.

When the width (W ₁₆ ) of the brim is 10 mm or more, the molten metal can be reliably cooled and solidified on the end surface (lower end surface) of the brim portion.
By setting the width (W ₁₆ ) of the flange to 300 mm or less, it is possible to prevent the molten metal from solidifying in the neck portion under the riser during induction heating and impairing the function of the riser.

(7) In the metal casting method of (6) above, when the outer diameter of the induction coil is (D ₄₀ ), [(D ₁₆ -D ₄₀ )/2] is preferably 10 mm or more.
When the value of (D ₁₆ −D ₄₀ )/2 is 10 mm or more, the flange is less likely to be affected by the lines of magnetic force generated by the induction coil, so that the flange can exhibit a sufficient cooling effect. .

(8) In the metal casting method of (6) or (7) above, it is preferable that the thickness (t ₁₆ ) of the flange in the flange-like portion is 3 mm or more.

(9) In the metal casting method of (6) to (8) above, the lower portion of the refractory pipe is positioned so that the distance (L ₂ ) from the lower end of the induction coil to the brim is 5 to 200 mm. Embedding in the mold is preferred.

According to the metal casting method of the present invention, the molten metal inside the refractory pipe does not flow to the outer peripheral side of the refractory pipe (the outer peripheral surface of the tubular portion).
This prevents molten metal from leaking out of the mold and contacting the induction coil.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows schematic structure of an example of the apparatus which enforces the casting method of this invention. 1 is a cross-sectional view showing the shape of a refractory pipe used in the casting method of the present invention; FIG. 1 is a photograph of a cast product including a feeder portion obtained by a casting method of an example. It is a photograph of a cast product including a feeder portion obtained by a casting method of a comparative example.

The metal casting method of the present invention, which is carried out using the apparatus shown in FIG. The refractory pipe 10 is erected, the induction coil 40 is loosely fitted on the outer peripheral side of the refractory pipe 10 (the upper portion not embedded in the mold 20), and the cavity 23 of the mold 20 and the refractory pipe 10 are separated. In this method, the molten metal M is poured into the internal space 13, and the molten metal M poured into the refractory pipe 10 is induction-heated to maintain the molten state, thereby forming a riser. It is characterized by using a refractory pipe 10 with 16.
In FIG. 1, 30 is a sheathed thermocouple for measuring the temperature of the molten metal M inside the refractory pipe 10 .

As shown in FIG. 2, the refractory pipe 10 used in the present invention is formed by integrally forming a tubular portion 11 forming an internal space 13 and a flange portion 16 formed at the lower end of the tubular portion 11. It becomes

As a constituent material of the refractory pipe 10, a material having refractory resistance to the induction heating temperature of the molten metal M (feeder) poured into the refractory pipe 10 can be mentioned.

Specifically, a material having a thermal expansion coefficient of 5.0×10 ⁻⁶ /K or less in the range of 1000 to 1650° C. can be preferably used. A more preferable range of thermal expansion coefficient in the range of 1000 to 1650° C. is 3.0×10 ⁻⁶ /K or less.
According to the refractory pipe 10 made of a material having a thermal expansion coefficient of 5.0×10 ⁻⁶ /K or less in the heating temperature range, damage such as cracks due to thermal shock during induction heating can be sufficiently prevented. can do. The constituent material of the refractory pipe 10 may or may not have induction heating properties.

Specific examples of such constituent materials include alumina graphite (thermal expansion coefficient at around 1000° C.=2×10 ⁻⁶ /K), zirconia graphite (thermal expansion coefficient at around 1000° C.=4×10 ⁻⁶ /K), fused silica (thermal expansion coefficient in the vicinity of 1000° C.=0.5×10 ⁻⁶ /K), conductive ceramics and graphite.

The outer diameter (D ₁₁ ) of the tubular portion 11 is preferably 50-400 mm, more preferably 80-250 mm, and a preferred example is 122 mm.
The inner diameter (d ₁₁ ) of the tubular portion 11 is preferably 10-390 mm, more preferably 40-200 mm, and a preferred example is 80 mm.
The wall thickness [t ₁₁ =(D ₁₁ -d ₁₁ )/2] of the tubular portion 11 is preferably 3 to 50 mm, more preferably 10 to 30 mm, and a preferred example is 21 mm.
The length (L ₁₀ ) of the refractory pipe 10 is preferably 150-1200 mm, more preferably 250-800 mm, and a preferred example is 352 mm.

The outer diameter (D ₁₆ ) of the brim 16 is preferably 100-800 mm, more preferably 150-400 mm, and a preferred example is 222 mm.

The width [W ₁₆ =(D ₁₆ -D ₁₁ )/2] of the flange portion 16 is preferably 10 to 300 mm, more preferably 30 to 150 mm, and a preferred example is 50 mm.

Since the width (W ₁₆ ) of the flange is 10 mm or more, the molten metal M flowing out from the lower end opening of the refractory pipe 10 can be reliably cooled and solidified on the lower end surface 17 of the flange 16 .
In addition, since the width (W ₁₆ ) of the flange is 300 mm or less, heat radiation from the flange-shaped portion 16 is appropriately suppressed, so that the neck portion under the riser (from the lower end of the induction coil 40 to the cavity 23) during induction heating. It is possible to prevent the molten metal M from solidifying and impairing the function of the riser.

The thickness (t ₁₆ ) of the flange portion 16 is preferably 3 mm or more, more preferably 10 to ₅₀ mm. be.
If the thickness (t ₁₆ ) of the flange is too small, the molten metal M flowing out from the lower end opening of the refractory pipe 10 may not be sufficiently cooled.

The refractory pipe 10 is erected so that the lower portion including the flange 16 is embedded inside the mold 20 .
In FIG. 1, the position of the lower end surface 17 of the flange 16 matches the position of the upper end surface 24 of the cavity 23, but the height of the lower end surface 17 of the flange 16 and the upper end surface 24 of the cavity 23 is the same as that of the cavity 23. The refractory pipes 10 may be erected so as to be spaced apart in the direction.

A mold 20 in which the refractory pipe 10 is erected is composed of an upper mold 21 and a lower mold 22 and has a pouring port 25 and a cavity 23 .
As a material for the mold 20, all mold materials used for ordinary cast iron, cast steel, and non-ferrous castings can be used. For example, shell mode sand, chamotte-based refractory material, graphite-based refractory material, zircon-based refractory material, chromite-based refractory material, etc. can be applied.

In order to induction-heat the molten metal M poured into the refractory pipe 10, an induction coil 40 is loosely fitted around the outer circumference of the refractory pipe 10 (the upper portion not embedded in the mold 20). The induction coil 40 is not particularly limited, and conventionally known coils used for heating risers can be used.
At least the coil inner surface and the coil lower surface of the induction coil 40 are preferably lined with a refractory material.

The inner diameter (d ₄₀ ) of the induction coil 40 is slightly larger than the outer diameter (D ₁₁ ) of the tubular portion 11 so that the induction coil 40 can be loosely fitted around the outer circumference of the refractory pipe 10 .

In addition, the outer diameter (D ₄₀ ) of the induction coil 40 is preferably smaller than the outer diameter (D ₁₆ ) of the flange portion 16 of the refractory pipe 10, and the value of [(D ₁₆ - D ₄₀ )/2] is preferably 10 mm or more.

If the value of (D ₁₆ −D ₄₀ )/2 is 10 mm or more, the flange portion 16 is less likely to be affected by the magnetic lines of force of the induction coil, and the molten metal M flowing out from the lower end opening of the refractory pipe 10 is It can be reliably cooled and solidified on the lower end surface of the portion 16 .

The length (L ₁ ) of the neck portion from the lower end of the induction coil 40 to the upper end of the cavity 23 is preferably 15-250 mm, and a preferred example is 80 mm.
Also, the length (L ₂ ) from the lower end of the induction coil 40 to the brim portion 16 is preferably 5 to 200 mm, and a preferred example is 59 mm.
By ensuring this length (L ₂ ) sufficiently, the flange 16 is less likely to be affected by the lines of magnetic force generated by the induction coil, and the molten metal M that flows out from the lower end opening of the refractory pipe 10 is removed from the flange 16. It can be reliably cooled and solidified at the lower end surface 17 .

The induction coil 40 is preferably detachably loosely fitted. For example, when the molten metal M is poured into the cavity 23 of the mold 20 and the inside of the refractory pipe 10, the induction coil 40 is attached and induction heating is performed. is preferably started.

The induction heating temperature of the induction coil 40 is preferably 1400° C. or higher, more preferably 1450° C. or higher, and particularly preferably 1500° C. or higher.

By computer-controlling the induction heating, the temperature of the molten metal in the refractory pipe 10 can be program-controlled. The program pattern for program control may be obtained by actually measuring the solidification pattern of the optimum feeder plan used in actual operation, and using this pattern as the program pattern.

<Example>
Cast steel was cast using an apparatus having a cross-sectional structure as shown in FIG.
The cast steel used had the following composition and a melting temperature of about 1600°C.
(composition)
C: 0.13 wt%, Si: 0.45 wt%, Mn: 0.5 wt%, Cr: 0.5 wt%, balance Fe and unavoidable impurities
The specifications of the refractory pipe 10 and the mold 20 that constitute the device, and the induction heating conditions are as follows.

・Material of refractory pipe 10: Alumina graphite ・Length (L ₁₀ ) of refractory pipe 10: 352 mm
・Dimensions of tubular portion 11: outer diameter (D ₁₁ ) 122 mm, inner diameter (d ₁₁ ) 80 mm
・Dimensions of flange 16: outer diameter (D ₁₆ ) 222 mm, thickness (t ₁₆ ) 21 mm
・Dimensions of mold 20: Length 800 mm x Width 800 mm x Height 600 mm
・Dimensions of cavity 23: φ400 mm × 120 mm
・Dimensions of the induction coil 40: outer diameter (D ₄₀ ) 215 mm, inner diameter (d ₄₀ ) 140 mm,
length 315mm
・Neck length (L ₁ ): 80 mm
・Length (L ₂ ) from the lower end of the induction coil 40 to the flange 16: 59 mm

Also, the casting conditions and the induction heating conditions are as follows.
・Pouring temperature: about 1500℃
・Induction heating temperature and induction heating time:
Temperature: about 1600°C, time: 5 hours

As shown in FIG. 3 (photograph), the cast product obtained in this example did not show any trace of leakage of molten metal (melt leakage) at the boundary with the riser portion.

<Comparative example>
Cast steel was cast in the same manner as in Examples except that a refractory pipe (outer diameter: 122 mm, inner diameter: 80 mm, length: 352 mm) without a flange was used.
As shown in FIG. 4 (photograph), the cast product obtained in this comparative example had traces of leakage of molten metal (melt leakage) at the base of the riser portion.

REFERENCE SIGNS LIST 10 refractory pipe 11 tubular portion 13 internal space of refractory pipe 16 brim portion 17 lower end surface of brim portion 20 mold 21 upper mold 22 lower mold 23 cavity of mold 24 upper end surface of cavity 25 spout 30 thermocouple 40 induction Coil M Molten metal

Claims (9)

The lower part of the refractory pipe is embedded in the mold, the refractory pipe is erected so that the inner space of the refractory pipe communicates with the cavity of the mold, and the refractory pipe is embedded in the mold. An induction coil is loosely fitted on the outer peripheral side of the upper part that is not covered, and metal is poured into the cavity of the mold and the inside of the refractory pipe, and the metal poured into the inside of the refractory pipe is induction-heated. In a metal casting method in which the feeder is carried out by maintaining the molten state by
A metal casting method, wherein the refractory pipe comprises a tubular portion forming the internal space and a brim portion formed at the lower end of the tubular portion. 2. A metal casting method according to claim 1, wherein said metal poured into said refractory pipe is induction-heated to 1400[deg.] C. or higher. 3. The method of claim 2, wherein said metal is cast steel. The metal casting method according to any one of claims 1 to 3, wherein the coefficient of thermal expansion of the material constituting the refractory pipe is 5.0 × 10 ^-6 /K or less in the range of 1000 to 1650°C. . 5. The method of casting metal according to claim 4, wherein said refractory pipe is composed of any one of alumina graphite, zirconia graphite, fused silica, conductive ceramic and graphite. The tubular portion has an outer diameter (D ₁₁ ) of 50 to 400 mm,
The outer diameter (D ₁₆ ) of the brim-shaped portion is 100 to 800 mm,
The metal casting method according to any one of claims 1 to 5, wherein the width (W ₁₆ ) of the flange of the flange-like portion is 10 to 300 mm. 7. The metal casting method according to claim 6, wherein [(D ₁₆ -D ₄₀ )/2] is 10 mm or more, where (D ₄₀ ) is the outer diameter of the induction coil. A metal casting method according to claim 6 or 7, characterized in that the thickness ( _t16 ) of the flange in the flange-like portion is 3 mm or more. The lower part of the refractory pipe is embedded in the mold so that the distance (L ₂ ) from the lower end of the induction coil to the flange is 5 to 200 mm. A metal casting method according to any one of the preceding claims.

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