Method for manufacturing molds and continuous casting rods for continuous casting.

Abstract

To provide a casting mold for continuous casting that does not require periodic graphite ring clearing work, and a manufacturing method for continuous casting rods using the casting mold.SOLUTION: The casting mold for continuous casting 100 according to the present invention is used for continuous casting and comprises a cylindrical casting mold body 20 having openings at both ends, one end of which is an inlet 21 for molten metal and the other end of which is a cast outlet 22 for a cast ingot, and a carbon ring 10 placed on an inner surface 20A of the mold body 20. The carbon ring 10 is configured with stacking of a first ring part 10a at one end and a second ring part 10b at the other end.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mold for continuous casting and a method for manufacturing a continuously cast bar.

Background Art

[0002] Conventionally, continuous casting of aluminum or an aluminum alloy has been performed by a horizontal continuous casting method, a vertical continuous casting method, etc. using a metal mold. In this continuous casting, molten metal such as an aluminum alloy is sent into the mold, the molten metal is cooled in the mold to solidify the surface, and further, cooling water is supplied to the surface of the ingot sent out from the mold to solidify it to the inside, thereby producing an ingot.

[0003] In a metal mold, in order to prevent seizure between the inner peripheral surface of the mold and the outer surface of the molten metal, it is necessary to supply a casting lubricant to the contact portion between the mold and the molten metal.

[0004] A vertical continuous casting apparatus for manufacturing an aluminum alloy casting bar is a metal mold, and as a method for supplying a casting lubricant, it is common to supply the lubricant by permeating it from a ring (graphite ring) made of graphite (carbon) installed on the inner peripheral surface of a cylindrical metal mold (for example, see Patent Document 1). In this method, the lubricant is press-fitted into the pores formed in the graphite ring, and during casting, the lubricant seeps out to the contact portion between the molten metal on the inner peripheral surface of the mold and the graphite ring. With this supply method, it is possible to supply a very small amount of lubricant continuously and uniformly in a very small amount. At this time, a gas may be introduced into the mold together with the lubricant.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, with conventional lubrication methods using graphite rings, repeated casting would cause the lubricating oil to carbonize and clog the high-temperature graphite rings, necessitating periodic replacement of the graphite rings.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a mold for continuous casting that does not require periodic replacement of graphite rings, and a method for manufacturing a continuous casting rod using the same. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means.

[0009] One aspect of the present invention is a mold for continuous casting used in continuous casting, comprising a cylindrical mold body having one end as a molten metal inlet and the other end as an ingot casting outlet, and a carbon ring disposed on the inner circumferential surface of the mold body, wherein the carbon ring is constructed by stacking a first ring portion disposed on the side of the one end and a second ring portion disposed on the side of the other end.

[0010] Aspect 2 of the present invention is a continuous casting mold according to aspect 1, wherein the mold body has a lubricating oil supply path connected to the second ring portion and a gas supply path connected to the second ring portion and spaced apart from the lubricating oil supply path, and the connecting supply portion that connects the lubricating oil supply path and the second ring portion is positioned closer to the first ring portion than the connecting supply portion that connects the gas supply path and the second ring portion.

[0011] A third aspect of the present invention is a continuous casting mold according to either aspect 1 or aspect 2, wherein a groove is formed on the surface of the second ring portion that overlaps with the first ring portion, allowing the lubricating oil supplied from the lubricating oil supply path to drain to the molten metal side.

[0012] Aspect 4 of the present invention is a continuous casting mold according to either aspect 1 or aspect 2, wherein, when viewed from the direction connecting one end and the other end, the connection between the lubricating oil supply path and the second ring portion and the connection between the gas supply path and the second ring portion are arranged to overlap.

[0013] Aspect 5 of the present invention is a continuous casting mold according to either aspect 1 or aspect 2, wherein a lubricating oil flow groove is formed in the second ring portion along its inner circumferential surface, through which the lubricating oil supplied from the lubricating oil supply path passes.

[0014] Aspect 6 of the present invention is a continuous casting mold according to either aspect 1 or aspect 2, wherein a gas flow groove is formed in the second ring portion along its inner circumferential surface, through which the gas supplied from the gas supply path passes.

[0015] Aspect 7 of the present invention is a continuous casting mold according to either aspect 1 or aspect 2, wherein the length of the second ring portion in the direction connecting the one end and the other end is longer than that of the first ring portion.

[0016] Aspect 8 of the present invention relates to a continuous casting mold according to either aspect 1 or aspect 2, wherein of the first ring portion and the second ring portion, at least the second ring portion has a bulk density of 1.65 to 1.9 g / cm³. 3 It is made of graphite material with a bending strength of 30 MPa to 98 MPa.

[0017] Aspect 9 of the present invention is a method for manufacturing a continuous casting rod, which involves manufacturing a continuous casting rod using a continuous casting mold according to either Aspect 1 or Aspect 2.

[0018] Aspect 10 of the present invention relates to the method for manufacturing a continuous casting rod according to aspect 9, wherein the supply amounts of lubricating oil and gas are controlled independently. [Effects of the Invention]

[0019] The present invention provides a continuous casting mold that does not require periodic replacement of the graphite ring. [Brief explanation of the drawing]

[0020] [Figure 1] It is a schematic cross-sectional view of a mold for continuous casting according to the present invention. [Figure 2] It is a diagram for explaining a method of manufacturing a continuously cast bar using a vertical continuous casting apparatus equipped with the mold for continuous casting shown in FIG. 1. [Figure 3] It is an enlarged schematic cross-sectional view near the carbon ring. [Figure 4] (a) is a schematic cross-sectional view showing the first ring portion 10a and the second ring portion 10b constituting the carbon ring 10 separated from each other, and (b) is a schematic plan view of the second ring portion 10b. [Figure 5] It is a conceptual diagram for conceptually explaining the operation and effect of the mold for continuous casting according to the present invention. [Figure 6] It is a graph comparing the transition of lubricating oil pressure according to the number of times of use of the mold between the case of using a mold for continuous casting provided with a split carbon ring and the case of using a mold for continuous casting provided with an integral carbon ring. [Embodiments for Carrying Out the Invention]

[0021] Hereinafter, a mold for continuous casting according to an embodiment of the present invention and a method for manufacturing a continuously cast bar using the same will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show, for the sake of convenience, the characteristic parts enlarged in order to make the features of the present invention easy to understand, and the dimensional ratios of each component may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and it can be appropriately modified and implemented within the range where the effects are achieved. In some cases, it may be drawn exaggeratedly for easy understanding.

[0022] [Mold for Continuous Casting] Figure 1 shows a schematic cross-sectional view of the continuous casting mold according to the present invention. Figure 2 is a diagram illustrating a method for manufacturing a continuously cast rod using a vertical continuous casting apparatus equipped with the continuous casting mold shown in Figure 1. Figure 3 is an enlarged schematic cross-sectional view of the vicinity of the carbon ring.

[0023] The continuous casting mold 100 shown in Figure 1 is a continuous casting mold used in continuous casting, The mold comprises a cylindrical mold body 20 having openings at both ends, with one end being a molten metal inlet 21 and the other end being a casting outlet 22 for the ingot, and a carbon ring 10 positioned on the inner circumferential surface 20A of the mold body 20. The carbon ring 10 is constructed by stacking a first ring portion 10a positioned on one end and a second ring portion 10b positioned on the other end. In Figure 1, the direction in which the first ring portion 10a and the second ring portion 10b are stacked (the direction connecting one end and the other) is defined as the Z direction, the direction perpendicular to the Z direction and parallel to the plane of the paper is defined as the X direction, and the direction perpendicular to the Z direction and perpendicular to the plane of the paper is defined as the Y direction. In the following, a carbon ring consisting of a first ring section and a second ring section may be referred to as a "split-type carbon ring."

[0024] The continuous casting apparatus equipped with a mold 100 for continuous casting is a vertical continuous casting apparatus that supplies molten metal L from the upper side of a cylindrical mold body 20 that is open in the vertical direction, and continuously extracts the solidified ingot S, which has been cooled by the supply of cooling water H, from the lower side of the mold body 20. A vertical continuous casting apparatus equipped with a continuous casting mold 100 can be used for continuous casting of aluminum alloy ingots S, such as aluminum alloy slabs (rectangular cross-section) or aluminum billets (circular cross-section). The type of ingot S is not limited to the aforementioned aluminum alloy; any metal that can be continuously cast using this vertical continuous casting apparatus is acceptable.

[0025] The mold body 20 has a lubricating oil supply path 31 connected to the second ring portion 10b, and a gas supply path 32 connected to the second ring portion 10b and positioned spaced apart from the lubricating oil supply path 31. The connecting supply section 31a that connects the lubricating oil supply path 31 and the second ring portion 10b is positioned closer to the first ring portion 10a in the Z direction than the connecting supply section 32a that connects the gas supply path 32 and the second ring portion 10b. Examples of gases supplied from the gas supply path 32 include air, a gas mixture (e.g., oxygen + inert gas), and an inert gas.

[0026] The lubricating oil supply path 31, which supplies lubricating oil into the mold, and the gas supply path 32, which supplies gas, are arranged separately and do not share a common surface. This configuration prevents the effects of pressure differences (interference, backflow, etc.) based on the respective supply amounts of lubricating oil and gas. Furthermore, since the lubricating oil supply path 31 and the gas supply path 32 are provided independently, the supply amounts of lubricating oil and gas can be controlled independently.

[0027] In the illustrated example, both the connection supply section 31a and the connection supply section 32a are positioned within the mold body 20 in an annular shape along the outer surface of the annular carbon ring 10 (second ring section 10b). However, the lubricating oil supply path 31 may be inserted into the second ring section 10b and the connection section 31a may be positioned within the carbon ring 10. Similarly, the gas supply path 32 may be inserted into the second ring section 10b and the connection section 32a may be positioned within the carbon ring 10. Alternatively, one or both of the connection section 31a or 32a may be positioned within the carbon ring 10.

[0028] In the illustrated example, the connection supply unit 31a and connection supply unit 32a are positioned so as not to overlap when viewed from the Z direction in a plan view, but they may be positioned so as to overlap.

[0029] A lubricating oil flow groove may be formed in a circumferential manner within the second ring portion 10b, through which the lubricating oil supplied from the lubricating oil supply path 31 passes. The circumferential shape can be one full turn or less than one full turn. A gas flow groove may be formed in a circumferential manner within the second ring portion 10b, through which the gas supplied from the gas supply path 32 passes. The circumferential shape can be one or less than one rotation.

[0030] In the Z direction, the connecting supply unit 31a, which connects the lubricating oil supply path 31 and the second ring portion 10b, is located on the upper side of the second ring portion 10b, and the connecting supply unit 32a, which connects the gas supply path 32 and the second ring portion 10b, is located on the lower side of the second ring portion 10b. This configuration provides the following effects. Lubricating oil supplied from the lubricating oil supply path 31 descends by gravity along the inner circumferential surface 10bAA of the second ring portion 10b via the connection supply section 31a. Meanwhile, gas supplied from the gas supply path 32 is discharged from the inner circumferential surface 10bAA of the second ring portion 10b via the connection supply section 32a. Due to the effect of the gas (dense air bubbling caused by the porosity of the carbon material), the gas is discharged over a wide surface of the carbon second ring portion 10b. With the gas discharged in this state, the lubricating oil that has descended by gravity becomes foamy lubricating oil, forming an insulating layer near the molten metal contact surface of the mold and acting as a sealing layer for the supplied molten metal. This prevents the molten metal from contacting the inner surface of the mold, resulting in a continuous casting rod with a smooth outer surface. Furthermore, the synergistic effect hinders primary cooling, thinning the reverse segregation layer around the surface. In addition, since the gas does not permeate the carbon ring 10, there are no restrictions on the type of oil, and long-term maintenance-free use is possible unless damaged.

[0031] The carbon ring 10 is an annular member made of carbon. The carbon ring 10 is constructed by stacking a first ring portion 10a and a second ring portion 10b, and as will be described in detail later, the lubricating oil supplied from the lubricating oil supply path 31 is supplied to the inner circumferential surface of the mold through the gap G between the stacked first ring portion 10a and the second ring portion 10b. Thus, the carbon ring 10 is not constructed in a way that allows the lubricating oil to seep out to the inner circumferential surface of the mold through pores in the graphite material, as is the case with conventional graphite rings. Therefore, it is not essential that the material of the carbon ring 10 has pores through which the lubricating oil seeps out. However, the lubricating oil may seep out to the inner circumferential surface of the mold not only through the gap between the stacked first ring portion 10a and the second ring portion 10b, but also through pores in the material, as is the case with conventional graphite rings. Furthermore, from the viewpoint of heat resistance to molten metal, graphite remains preferable as the carbon material constituting the carbon ring 10, but it is not limited to this. Furthermore, the carbon ring 10 may be manufactured by compressing fine graphite particles by extrusion or hydrostatic pressure to have a predetermined pore structure.

[0032] There are no particular restrictions on the method of attaching the carbon ring 10 to the mold body 20. For example, it can be attached to the mold body 20 by shrink-fitting, taking advantage of the difference in thermal expansion coefficients between the mold body 20 and the carbon ring 10. Since carbon has a lower thermal expansion coefficient than the metal that makes up the mold body 20, if the inner diameter of the mold body 20 is set to be smaller than the outer diameter of the carbon ring 10 at room temperature, and the carbon ring 10 is fitted into the mold body 20 after its inner diameter has expanded due to heating, the carbon ring 10 will be fixed in a tightened state to the mold body 20 as the temperature of the mold 10 decreases. When attached by shrink-fitting, the mold body 20 and the carbon ring 10 are in close contact and there is no gap between them, so heat transfer from the carbon ring 10 to the mold body 20 occurs quickly during continuous casting. In addition, since the mold body 20 and the carbon ring 10 are in close contact over the entire circumferential direction, there is no uneven cooling in the circumferential direction.

[0033] The carbon ring 10 has a configuration in which a first ring portion 10a and a second ring portion 10b are stacked on top of each other (combined), but the first ring portion 10a and the second ring portion 10b may be made of carbon materials having the same properties, or they may be made of carbon materials having different properties. Of the first ring portion 10a and the second ring portion 10b, at least the second ring portion 10b has a bulk density of 1.65 to 1.9 g / cm³ 3 Therefore, a graphite material with a bending strength of 30 MPa to 98 MPa may be used. This is because a ring portion made of a graphite material having such properties allows sufficient permeability of the gas supplied from the gas supply path 32 and has sufficient strength for use in continuous casting of aluminum alloys.

[0034] The carbon ring 10 may be a single carbon ring that has been divided into two parts: a first ring portion 10a and a second ring portion 10b.

[0035] In the carbon ring 10, the length in the Z direction is such that the length of the second ring portion 10b (indicated by L2 in Figure 3) is longer than the length of the first ring portion (indicated by L1 in Figure 3).

[0036] Figure 4(a) is a schematic cross-sectional view showing the first ring portion 10a and the second ring portion 10b constituting the carbon ring 10 spaced apart for illustrative purposes. As shown in Figure 3, when fitted into the inner circumferential surface of the continuous casting mold 20, there is only a small gap G (see Figure 3) formed between the mating surfaces (stacking surfaces, overlapping surfaces) 10aA and 10bA of the first ring portion 10a and the second ring portion 10b, respectively, according to the flatness of each mating surface. In contrast, the mating surface 10bA of the second ring portion 10b may be provided with grooves or recesses (three of which are indicated by reference numeral 10ba) that allow lubricating oil supplied from the lubricating oil supply path 31 to drain to the molten metal side, as shown in Figure 4(b).

[0037] In the example shown in Figure 4(b), grooves with the center of the hole facing O are formed at equal intervals in a plan view from the Z direction, but the number of grooves is not limited to this, and some grooves may be unevenly spaced, and all grooves may even be unevenly spaced. From the viewpoint of uniformly supplying lubricating oil to the inner circumferential surface 20A of the mold body 20, it is preferable to arrange multiple grooves at equal intervals. The depth of the groove 10ba can be, for example, about 0.015 mm to 2 mm.

[0038] Figure 5 shows a conceptual diagram illustrating the effects of the continuous casting mold according to the present invention. In the continuous casting mold 100 shown in Figure 1, in the Z direction, the connecting supply section 31a that connects the lubricating oil supply path 31 to the second ring section 10b is located on the upper side of the second ring section 10b, and the connecting supply section 32a that connects the gas supply path 32 to the second ring section 10b is located on the lower side of the second ring section 10b. Furthermore, the carbon ring 10 has a configuration in which the first ring section 10a and the second ring section 10b are stacked in the Z direction. Lubricating oil supplied from the lubricating oil supply path 31 is supplied to the inner circumferential surface 10bAA of the second ring portion 10b through the gap G between the first ring portion 10a and the second ring portion 10b via the connecting supply section 31a. The lubricating oil LUB supplied to the inner circumferential surface 10bAA of the second ring portion 10b descends the inner circumferential surface 10bAA by its own gravity. Meanwhile, the gas supplied from the gas supply path 32 is discharged from the inner circumferential surface 10bAA of the second ring portion 10b via the connecting supply section 32a, and the gas is discharged over a wide surface of the second ring portion 10b by the air bubbling effect. As gas is discharged in this state, the lubricating oil that has descended by its own gravity becomes foamy lubricating oil FLUB, which forms an insulating layer near the molten metal contact surface of the mold and acts as a sealing layer for the supplied molten metal, so that the molten metal does not come into contact with the inner surface of the mold, and a continuous casting rod with a smooth outer surface can be obtained.

[0039] Figure 6 is a graph comparing the changes in lubricating oil supply pressure (lubricating oil pressure) over the number of mold uses when using a continuous casting mold equipped with a segmented carbon ring according to the present invention and when using a conventional continuous casting mold equipped with a one-piece carbon ring. The material of the carbon ring is graphite.

[0040] In the graph in Figure 6, the horizontal axis represents the number of times the mold was used (i.e., the number of times continuous casting rods were manufactured), and the vertical axis represents the ratio of the operating pressure at each number of uses, with the initial lubrication pressure set to 1. Clogging is determined when the ratio of the operating pressure to the initial pressure of the lubricating oil is 1.5.

[0041] With conventional one-piece carbon rings, the lubricating oil pressure exceeded the clogging detection pressure after the fourth use. In contrast, with split carbon rings, the ratio of the operating pressure to the initial pressure increased to approximately 1.03 after the third use, and the lubricating oil pressure remained unchanged even after the twelfth use. As shown above, when using the segmented carbon ring according to the present invention, clogging of the carbon ring is drastically reduced compared to when using a conventional one-piece carbon ring.

[0042] [Method for manufacturing continuous casting rods] The method for manufacturing a continuous cast rod according to the present invention allows for the manufacture of a continuous cast rod using the continuous casting mold of the present invention as described above.

[0043] In the production of a continuously cast rod using the mold for continuous casting of the present invention, while introducing lubricating oil and gas between the molten metal L and the carbon ring 10, the molten metal L undergoes primary cooling from the inner circumferential surface of the carbon ring 10, solidification progresses from the outer circumferential surface of the molten metal L towards the center, the molten metal L descends and solidifies in the cooling water H, and a continuously cast rod is produced. [Explanation of Symbols]

[0044] 10 Carbon Rings 10a First Ring Section 10b Second Ring Section 20. Mold body 21 Inlet 22 Outlet 31 Lubrication oil supply route 32 Gas supply path

Claims

1. A mold for continuous casting used in continuous casting, A cylindrical mold body, with one end serving as the molten metal inlet and the other end as the ingot casting outlet, The mold body comprises a carbon ring placed on the inner circumferential surface, The carbon ring is constructed by stacking a first ring portion located at one end and a second ring portion located at the other end, with a gap large enough for lubricating oil to pass through. The mold body has a lubricating oil supply path connected to the second ring portion and a gas supply path connected to the second ring portion and positioned apart from the lubricating oil supply path. A mold for continuous casting, wherein the connecting supply section that connects the lubricating oil supply path and the second ring section is positioned closer to the first ring section than the connecting supply section that connects the gas supply path and the second ring section.

2. The continuous casting mold according to claim 1, wherein a groove is formed on the surface of the second ring portion that overlaps with the first ring portion, allowing lubricating oil supplied from the lubricating oil supply path to drain to the molten metal side.

3. The continuous casting mold according to claim 1, wherein, when viewed from the direction connecting the one end and the other end, the connection portion between the lubricating oil supply path and the second ring portion and the connection portion between the gas supply path and the second ring portion are arranged to overlap.

4. The continuous casting mold according to claim 1, wherein the second ring portion has a lubricating oil flow groove formed in a circumferential manner along its inner circumferential surface, through which the lubricating oil supplied from the lubricating oil supply path passes.

5. The continuous casting mold according to claim 1, wherein a gas flow groove is formed in the second ring portion in a circumferential manner along the inner circumferential surface, through which the gas supplied from the gas supply path passes.

6. The continuous casting mold according to claim 1, wherein the length in the direction connecting the one end and the other end is such that the second ring portion is longer than the first ring portion.

7. Of the first and second ring portions, at least the second ring portion has a bulk density of 1.65 to 1.9 g / cm³. ３ The continuous casting mold according to claim 1, comprising a graphite material having a bending strength of 30 MPa to 98 MPa.

8. A method for manufacturing a continuous casting rod, comprising manufacturing a continuous casting rod using the continuous casting mold described in claim 1.

9. A method for manufacturing a continuous casting rod according to claim 8, wherein the supply amounts of lubricating oil and gas are independently controlled.

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