Metal Casting Method

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]

[0001] The present invention relates to a metal casting method, and more particularly to a casting method suitable for producing castings from metals with high melting points, such as cast steel. [Background technology]

[0002] In metal casting, a feeder is essential to prevent casting defects such as shrinkage cavities. Conventionally, efforts have been made to reduce the size of a feeder head by induction heating the feeder head portion (see Patent Document 1 below). Furthermore, the present applicant has proposed a metal casting method that can flexibly and economically accommodate a wide range of production formats, from small to large quantities, and that is also highly effective in improving the work of cutting off feeder sections. This method involves loosely fitting an induction coil around the outside of a refractory pipe that is embedded in and stands upright in the mold so as to communicate with the mold cavity, and when pouring metal, the molten metal in the refractory pipe is induction heated by the induction coil, causing the molten metal in the pipe to finally solidify (see Patent Document 2 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 55-64958 [Patent Document 2] Japanese Patent Application Publication No. 9-314310 Summary of the Invention [Problem to be solved by the invention]

[0004] When casting a metal with a high melting point, such as cast steel, using the metal casting method described in Patent Document 2, it is necessary to maintain the temperature of the metal poured into the refractory pipe at approximately 1500 to 1600°C by induction heating, and the refractory pipe also reaches a similar temperature. Furthermore, if the refractory pipe is made of an induction-heating material, the temperature of the refractory pipe may become higher than the temperature of the molten metal inside.

[0005] In such cases, some of the molten metal inside the refractory pipe may flow around the lower end surface of the refractory pipe embedded in the mold, rise along the outer surface of the refractory pipe (the interface with the mold, etc.), and leak out of the mold. If the molten metal leaking from the mold comes into contact with the induction coil, it may cause melting damage to the induction coil or short circuits between layers.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide a metal casting method in which molten metal inside a refractory pipe embedded and erected in a mold for use as a feeder does not flow to the outer periphery of the refractory pipe. [Means for solving the problem]

[0007] (1) A metal casting method of the present invention comprises embedding a lower portion of a refractory pipe in a mold, erecting the refractory pipe so that the internal space of the refractory pipe communicates with a cavity of the mold, loosely fitting an induction coil around the outer periphery of an upper portion of the refractory pipe that is not embedded in the mold, pouring metal into the cavity of the mold and into the refractory pipe, and induction heating the metal poured into the refractory pipe to maintain a molten state, thereby performing feeding, The fire-resistant pipe is characterized by comprising a tubular portion that defines the internal space, and a flange portion formed at the lower end of the tubular portion.

[0008] According to this metal casting method, the molten metal flowing out from the lower end opening of the refractory pipe is cooled at the end face (lower end face) of the flange and solidifies before reaching the outer periphery of the flange, thereby preventing the molten metal inside the refractory pipe from flowing to the outer periphery of the refractory pipe (the outer periphery of the tubular part).

[0009] (2) In the metal casting method of the present invention, it is preferable that the metal poured into the refractory pipe is induction heated to 1400° C. or higher. The use of a refractory pipe with a flange is particularly effective when heating the metal inside the refractory pipe at high temperatures of 1400°C or higher.

[0010] (3) In the metal casting method of (2) above, the metal is preferably cast steel. When casting steel, the steel inside the refractory pipe must be heated to 1500°C or more, so the use of a refractory pipe with a flange is particularly effective.

[0011] (4) In the metal casting method of the present invention, the thermal expansion coefficient of the material of the refractory pipe in the range of 1000 to 1650°C is 5.0 × 10 -6 / K or less is preferable.

[0012] (5) In the metal casting method of (4) above, the refractory pipe is preferably made of any one of alumina graphite, zirconia graphite, fused silica, conductive ceramics, and graphite.

[0013] (6) In the metal casting method of the present invention, the outer diameter (D 11 ) is 50 to 400 mm, and the outer diameter (D 16 ) is 100 to 800 mm, and the flange width [W 16 =(D 16 -D 11 ) / 2) is preferably 10 to 300 mm.

[0014] Width of the tsuba (W 16 ) is 10 mm or more, the molten metal can be reliably cooled and solidified at the end face (lower end face) of the flange-shaped portion. Width of the tsuba (W 16 ) is 300 mm or less, it is possible to prevent the molten metal in the neck portion below the feeder from solidifying during induction heating, thereby preventing the function of the feeder from being impaired.

[0015] (7) In the metal casting method of (6), the outer diameter of the induction coil is (D 40 ), then (D 16 -D 40 ) / 2) is preferably 10 mm or more. (D 16 -D 40 When the value of (distance between the flange and the core) / 2 is 10 mm or more, the flange is less susceptible to the influence of the magnetic lines of force from the induction coil, and therefore the flange can exert a sufficient cooling effect.

[0016] (8) In the metal casting method of (6) or (7), the thickness of the flange of the flange-shaped portion (t 16 ) is preferably 3 mm or more.

[0017] (9) In the metal casting methods (6) to (8) above, it is preferable that the lower portion of the refractory pipe is embedded in the mold so that the distance (L2) from the lower end of the induction coil to the flange-shaped portion is 5 to 200 mm. [Effects of the Invention]

[0018] According to the metal casting method of the present invention, the molten metal inside the refractory pipe does not flow to the outer periphery of the refractory pipe (the outer periphery of the tubular portion). This prevents the molten metal from leaking out of the mold and coming into contact with the induction coil. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an example of an apparatus for carrying out a casting method of the present invention. [Figure 2] 1 is a cross-sectional view showing the shape of a refractory pipe used in the casting method of the present invention. [Figure 3] 1 is a photograph of a cast product including a feeder obtained by the casting method of the example. [Figure 4] 1 is a photograph of a cast product including a feeder obtained by a casting method of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0020] The metal casting method of the present invention, which is carried out using the apparatus shown in Figure 1, involves embedding the lower part of a refractory pipe 10 in a mold 20, erecting the refractory pipe 10 so that its internal space 13 communicates with the cavity 23 of the mold 20, loosely fitting an induction coil 40 around the outer periphery of the refractory pipe 10 (the upper part not embedded in the mold 20), pouring molten metal M into the cavity 23 of the mold 20 and the internal space 13 of the refractory pipe 10, and inductively heating the molten metal M poured into the refractory pipe 10 to maintain the molten state, thereby performing feeding.The method is characterized by the use of a refractory pipe 10 having a flange-shaped part 16. In FIG. 1, 30 denotes a sheathed thermocouple for measuring the temperature of the molten metal M inside the refractory pipe 10 .

[0021] As shown in FIG. 2, the fire-resistant pipe 10 used in the present invention is formed by integrally molding a tubular portion 11 that forms an internal space 13 and a flange-like portion 16 formed at the lower end of the tubular portion 11.

[0022] The refractory pipe 10 may be made of a material having fire resistance that can withstand the induction heating temperature of the molten metal M (feeder) poured into the inside of the refractory pipe 10.

[0023] Specifically, the thermal expansion coefficient in the range of 1000 to 1650°C is 5.0 × 10 -6 / K or less. A more preferable range of the thermal expansion coefficient in the range of 1000 to 1650°C is 3.0 × 10 -6 / K or less. The thermal expansion coefficient in the heating temperature range is 5.0 x 10 -6 The fire-resistant pipe 10 made of a material having a temperature of 1000 K or less can sufficiently prevent damage such as cracks caused by thermal shock during induction heating. The material of the fire-resistant pipe 10 may or may not have induction heat-generating properties.

[0024] A specific example of such a material is 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 at around 1000°C = 0.5 × 10 -6 / K), conductive ceramics and graphite.

[0025] The outer diameter (D 11 ) is preferably 50 to 400 mm, more preferably 80 to 250 mm, and a suitable example is 122 mm. The inner diameter (d 11 ) is preferably 10 to 390 mm, more preferably 40 to 200 mm, and a suitable example is 80 mm. The wall thickness of the tubular portion 11 [t 11 =(D 11 -d 11 ) / 2) is preferably 3 to 50 mm, more preferably 10 to 30 mm, and a suitable example is 21 mm. Length of fire-resistant pipe 10 (L 10 ) is preferably 150 to 1200 mm, more preferably 250 to 800 mm, and a suitable example is 352 mm.

[0026] The outer diameter of the flange 16 (D 16 ) is preferably 100 to 800 mm, more preferably 150 to 400 mm, and a suitable example is 222 mm.

[0027] The width of the flange at the flange portion 16 [W 16 =(D 16 -D 11 ) / 2) is preferably 10 to 300 mm, more preferably 30 to 150 mm, and a suitable example is 50 mm.

[0028] Width of the tsuba (W 16) is 10 mm or more, the molten metal M flowing out from the lower end opening of the fire-resistant pipe 10 can be reliably cooled and solidified at the lower end surface 17 of the flange-shaped portion 16. Also, the width of the tsuba (W 16 ) is 300 mm or less, heat radiation from the flange portion 16 is appropriately suppressed, and therefore it is possible to prevent the molten metal M in the neck portion below the feeder head (the portion from the lower end of the induction coil 40 to the upper end of the cavity 23) from solidifying during induction heating, thereby preventing the function of the feeder head from being impaired.

[0029] The thickness of the flange 16 (t 16 ) is preferably 3 mm or more, more preferably 10 to 50 mm. 11 ) is 21mm. Thickness of the flange (t 16 ) is too small, the molten metal M flowing out from the lower end opening of the refractory pipe 10 may not be cooled sufficiently.

[0030] The refractory pipe 10 is erected so that the lower portion including the flange portion 16 is embedded inside the mold 20 . In Figure 1, the position of the lower end surface 17 of the flange-shaped portion 16 coincides with the position of the upper end surface 24 of the cavity 23, but the fire-resistant pipe 10 may be erected so that the lower end surface 17 of the flange-shaped portion 16 and the upper end surface 24 of the cavity 23 are spaced apart in the vertical direction.

[0031] The 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. Any mold material used for ordinary cast iron, cast steel, or non-ferrous castings can be used for the mold 20. For example, shell mode sand, chamotte refractory material, graphite-based refractory material, zircon-based refractory material, chromite-based refractory material, etc. can be used.

[0032] 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 periphery of the refractory pipe 10 (the upper part not embedded in the mold 20). The induction coil 40 is not particularly limited, and any conventionally known coil used for heating a feeder head can be used. At least the inner surface and the lower surface of the induction coil 40 are preferably lined with a refractory material.

[0033] The inner diameter (d 40 ) is the outer diameter (D 11 ) is slightly larger than

[0034] In addition, the outer diameter (D 40 ) is the outer diameter (D 16 ) and preferably smaller than (D 16 -D 40 ) / 2] is preferably 10 mm or more.

[0035] (D 16 -D 40 If the value of ) / 2 is 10 mm or more, the flange portion 16 is less susceptible to the influence of the magnetic field lines from the induction coil, and the molten metal M flowing out from the lower end opening of the fire-resistant pipe 10 can be reliably cooled and solidified on the lower end surface of the flange portion 16.

[0036] The length (L1) of the neck portion from the lower end of the induction coil 40 to the upper end of the cavity 23 is preferably 15 to 250 mm, and a suitable example is 80 mm. Furthermore, the length (L2) from the lower end of the induction coil 40 to the flange portion 16 is preferably 5 to 200 mm, and a suitable example is 59 mm. By ensuring this length (L2) sufficiently, the flange-shaped portion 16 is less susceptible to the influence of the magnetic lines of force from the induction coil, and the molten metal M flowing out from the lower end opening of the fire-resistant pipe 10 can be reliably cooled and solidified at the lower end surface 17 of the flange-shaped portion 16.

[0037] It is preferable that the induction coil 40 is loosely fitted so that it can be attached and detached freely. For example, it is preferable that the induction coil 40 is attached and induction heating is started when the molten metal M is poured into the cavity 23 of the mold 20 and the inside of the refractory pipe 10.

[0038] The induction heating temperature by the induction coil 40 is preferably 1400°C or higher, more preferably 1450°C or higher, and particularly preferably 1500°C or higher.

[0039] By controlling the induction heating by a computer, the temperature of the molten metal in the refractory pipe 10 can be controlled by a program. The program pattern for program control can be determined by actually measuring the solidification pattern of the optimum feeder method used in actual operation, and using this pattern as the program pattern. [Example]

[0040] <Example> Cast steel was cast using an apparatus with a cross-sectional structure as shown in Figure 1. The cast steel used had the following composition and a melting temperature of approximately 1600°C. (composition) C: 0.13wt%, Si: 0.45wt%, Mn: 0.5wt%, Cr: 0.5wt%, balance Fe and unavoidable impurities The specifications of the refractory pipe 10 and mold 20 constituting the apparatus, as well as the induction heating conditions, are as follows:

[0041] Fireproof pipe 10 material: Alumina graphite Length of fire-resistant pipe 10 (L 10 ):352mm Dimensions of the tubular portion 11: outer diameter (D 11 )122mm, inner diameter (d 11 )80mm Dimensions of the flange 16: Outer diameter (D 16 ) 222mm, thickness (t 16 )21mm Mold 20 dimensions: length 800mm x width 800mm x height 600mm Cavity 23 dimensions: φ400mm x 120mm Induction coil 40 dimensions: outer diameter (D 40 )215mm, inner diameter (d 40 )140mm, Length: 315mm Neck length (L1): 80mm Length from the bottom of the induction coil 40 to the flange 16 (L2): 59 mm

[0042] The casting conditions and induction heating conditions are as follows: ·Pouring temperature: approx. 1500℃ Induction heating temperature and induction heating time: Temperature: Approximately 1600°C, Time: 5 hours

[0043] As shown in FIG. 3 (photograph), the cast product obtained in this example showed absolutely no trace of leakage of molten metal (melt leakage) at the boundary with the riser portion.

[0044] <Comparative Example> Cast steel was cast in the same manner as in Example 1, 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 molten metal leakage (melt leakage) at the base of the riser. [Explanation of symbols]

[0045] 10. Fire-resistant pipes 11 Tubular part 13. Internal space of fire-resistant pipes 16 Flange 17 Lower end surface of flange 20 Mold 21 Upper mold 22 Lower mold 23 Mold cavity 24 Top surface of cavity 25 Pouring spout 30 Thermocouple 40 induction coil M Molten metal

Claims

1. A metal casting method comprising: embedding a lower portion of a refractory pipe in a mold; erecting the refractory pipe so that an internal space of the refractory pipe communicates with a cavity of the mold; loosely fitting an induction coil around an outer periphery of an upper portion of the refractory pipe that is not embedded in the mold; pouring metal into the cavity of the mold and into the refractory pipe; and induction heating the metal poured into the refractory pipe to maintain a molten state, thereby performing a head feed, The metal casting method is characterized in that the refractory pipe comprises a tubular portion that forms the internal space and a flange portion formed at the lower end of the tubular portion.

2. 2. The metal casting method according to claim 1, wherein the metal poured into the refractory pipe is induction heated to 1400° C. or higher.

3. 3. The metal casting method of claim 2, wherein the metal is cast steel.

4. The thermal expansion coefficient of the material of the fire-resistant pipe in the range of 1000 to 1650°C is 5.0 × 10 -6 4. The metal casting method according to claim 1, wherein the melting point is 0.15 to 0.55 K.

5. 5. The metal casting method according to claim 4, wherein the refractory pipe is made of any one of alumina graphite, zirconia graphite, fused silica, conductive ceramic, and graphite.

6. The outer diameter (D 11 ) is 50 to 400 mm, The outer diameter (D 16 ) is 100 to 800 mm, The width of the flange at the flange-shaped portion (W 16 6. The metal casting method according to claim 1, wherein the distance between the first and second ends of the casting die is 10 to 300 mm.

7. The outer diameter of the induction coil is (D 40 ) then, [(D 16 -D 40 7. The metal casting method according to claim 6, wherein the distance between the first and second ends of the first and second grooves is 10 mm or more.

8. The thickness of the flange at the flange-shaped portion (t 16 8. The metal casting method according to claim 6, wherein the thickness of the hole is 3 mm or more.

9. The distance from the lower end of the induction coil to the flange (L 2 9. The metal casting method according to claim 6, wherein the lower portion of the refractory pipe is embedded in the mold so that the length of the refractory pipe is 5 to 200 mm.

Images