KR20080114045A - Mold for air-slip type noncircular continuous casting and casting method of aluminum alloy thereof - Google Patents

Abstract

An air slip type non-circular continuous casting mold and an aluminium alloy casting method thereof are provided to obtain a stable air slip type non-circular continuous casting mold without a black lead ring shrink-on process used in the existing circular air slip mold. An air slip type non-circular continuous casting mold comprises a mold main body(20) in which a non-circular through-hole through which molten metal(80) moves is formed, a porous black lead ring(70) which is equipped on inner circumference of the mold main body and supplies gas and oil to the falling molten metal so that the molten metal is coagulated to a billet(85), and a conveying plate(95) transferring the molten metal downward. A coolant chamber(60) in which the coolant for cooling the billet surface is stored is formed inside the mold main body. A gas inlet(32) and an oil inlet(34) for supplying gas and oil to the inside of the porous black lead ring through the mold main body are connected to the upper end of the black lead ring.

Description

Mold for air-slip type noncircular continuous casting and casting method of aluminum alloy

Figure 1 is a cross-sectional view of the main part of the mold assembly showing that the air-slip aluminum alloy continuous casting method according to the prior art.

Figure 2 is a sectional view of the main portion showing a specific embodiment of the air-slip casting mold according to the present invention.

3 is a plan view showing a state that the graphite ring is seated on the seating portion of the inner body constituting a specific embodiment of the present invention.

4 is a plan view showing a graphite ring constituting a specific embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10 through hole 20 mold body

30: upper body 32: gas inlet

34: oil inlet 40: lower body

50: inner body 52: seating portion

54: coupling hole 56: cooling water discharge path

60: coolant chamber 70: graphite ring

80: molten metal 85: billet

90: asbestos gasket 95: transfer plate

99: boundary line

The present invention relates to an air slip continuous casting mold having a non-circular cross section and an aluminum casting method using the same.

Most of the currently produced aluminum extrusion billets adopt a continuous casting method using an air slip method, thereby obtaining excellent effects through various advantages. However, the air slip method is advantageous for aluminum casting in a circular cross section, but various problems are caused in the case of a non-circular cross section.

Here, the air slip method, unlike the conventional direct cooling method, by supplying oil and mixed gas (nitrogen and oxygen) directly to the billet surface through the porous graphite to the heat release by direct contact between the molten metal and the mold. Control in advance.

1 is a cross-sectional view showing that the billet is manufactured in a mold assembly employing such an air slip method. According to this, the molten through hole 1 'is formed by penetrating the mold main body 1 up and down. The molten through hole 1 ′ is a portion in which the molten metal 2 for filling the billet 9 to be described below is filled.

The graphite ring 3 surrounding the inner circumferential surface of the molten through hole 1 'is provided. The inner surface shape of the graphite ring 3 immediately becomes the outer surface shape of the billet 9. Since the graphite ring 3 is porous, it is supplied between the inner surface of the graphite ring 3 and the billet 9 by passing lubricant and nitrogen and oxygen gas to minimize friction between the mold and the billet. Reference numeral 5 denotes a cooling water supply unit.

In the lower inner side of the molten through hole (1 ') is a pull-out (7) is positioned to be elevated. The take-out table 7 lowers the molten metal 2 located on the take-out table 7 in a solidified state through the melt-through hole 1 'so that the billet 9 is continuously made to a predetermined length. will be.

In the mold assembly having such a configuration, the molten metal 2 is supplied to the molten metal through-hole 1 'in a state in which the lead table 7 is raised to the lower portion of the molten metal through-hole 1'. The molten metal 2 starts to solidify on the take-out table 7. At the beginning of casting, the drawer 7 is lowered at a constant casting speed lower than the maximum casting speed in order to maintain stability of the solidification interface.

However, the prior art as described above has the following problems.

That is, when the air slip method according to the prior art is used for aluminum casting having a non-circular cross section, casting becomes impossible. The graphite ring of the casting mold is integrally formed by a shrink fit process, and the graphite ring is In the case of thermal deformation, the degree of deformation is different due to the characteristics of the non-circular shape, which is caused by deformation of the shape and being removed from the casting mold.

In the prior art, since oil and gas are supplied from the side of the graphite ring, a gap is generated between the graphite ring and the mold body by the pressure of the gas and the oil, and the oil and gas are not smoothly supplied to the graphite ring. There was a problem that the air slip does not occur stably.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, an object of the present invention is aluminum having a non-circular cross-sectional shape without using the graphite ring shrink fit process used in the conventional circular mold for air slip It is to provide a continuous casting mold of a stable air slip method while minimizing the heat deformation of the graphite ring used in the alloy casting mold.

According to a feature of the present invention for achieving the object as described above, the present invention includes a mold body in which a non-circular through-hole through which the molten metal moves is formed; A porous graphite ring provided on the inner circumference of the mold main body to supply gas and oil to the surface of the molten metal to be dropped, thereby solidifying the molten metal into a billet; It is provided on the inner periphery of the mold body of the graphite ring, and comprises a transfer plate for transferring the molten metal downward: a cooling water chamber is formed inside the mold body to store the cooling water for cooling the billet surface : The cooling water chamber is formed on the back of the graphite ring: a gas inlet and an oil inlet for supplying gas and oil to the porous graphite ring through the mold body through the mold body.

In this case, the cooling water chamber may be formed at a height such that an upper end of the graphite ring is higher than a lower end of the cooling water chamber, and a lower end of the graphite ring is lower than an upper end of the cooling water chamber.

Alternatively, the cooling water chamber may be formed at a height such that an upper end of the graphite ring is lower than an upper end of the cooling water chamber, and a lower end of the graphite ring is higher than a lower end of the cooling water chamber.

On the other hand, the mold body, the upper portion of the chamber, one side of the lower surface to support the upper surface of the graphite ring, the upper portion of the gas inlet and oil inlet for supplying gas and oil to the upper portion of the graphite ring is formed A main body; A lower body constituting the lower and outer parts of the mold body; The inner body of the mold body may be combined with the upper body and the lower body, and may include an inner body having a seating portion on which the graphite ring is seated.

The graphite ring may have an upper surface supported by the upper body, and side and bottom surfaces thereof may be seated on the seating portion of the inner body to be fixed to the mold body.

In addition, an asbestos gasket may be provided between the graphite ring and the upper body.

In addition, the graphite ring may be divided into a plurality of pieces.

On the other hand, the inner circumferential surface of the graphite ring may be formed in a tapered shape that is wider in the downward direction so as to correspond to the change amount of the billet changed by the solidification shrinkage.

In addition, the lower body, a cooling water discharge path for supplying the cooling water of the cooling water chamber to the billet may be formed.

The diameter of the cooling water discharge path may be formed differently according to the calorific value of the billet, or may be formed with different densities for each part of the inner body.

On the other hand, the present invention is a continuous casting method of producing a billet having a non-circular cross-section through the inner surface of the transfer plate and the graphite ring tapered in the non-circular through the inner surface of the mold body to produce a billet having a non-circular cross-section, Allowing gas and oil introduced from the top to form a film on the surface of the molten metal to be solidified; The graphite ring is cooled by the cooling water of the cooling water chamber provided on the back of the graphite ring; It includes an air-slip aluminum alloy continuous casting method so that the boundary between the solidified billet and the molten metal is in contact with the inner surface of the graphite ring.

Here, the billet may be cooled by the cooling water supplied from the cooling water chamber and ejected from the cooling water discharge path under the graphite ring.

The cooling water may be ejected in different amounts depending on the amount of heat generated according to the form of the billet to be cast.

In addition, the amount of the cooling water may be determined by the number of the cooling water discharge paths or may be determined by the size of the cooling water discharge path.

According to the present invention having the configuration as described above, in casting an aluminum alloy having a non-circular cross section, there is an advantage that the durability of the mold can be increased and an aluminum alloy having a uniform composition can be produced.

Hereinafter, with reference to the accompanying drawings a specific embodiment of the continuous casting mold of the air slip method according to the present invention as described above will be described in detail.

Figure 2 is a cross-sectional view showing a specific embodiment of the air-slip casting mold according to the present invention, Figure 3 is a plan view showing a state that the graphite ring is seated on the seating portion of the inner body constituting a specific embodiment of the present invention. 4 is a plan view showing a graphite ring constituting a specific embodiment of the present invention.

As shown in these drawings, the air-slip casting mold constituting a specific embodiment of the present invention comprises a mold body 20 in which a non-circular through-hole 10 is formed.

The through-hole 10 has a shape corresponding to the cross-sectional shape of the billet to be cast, but may be formed in various forms, in the description of specific embodiments of the present invention, that is formed in the form of "b" for convenience of description. An example will be described (see FIG. 3).

On the other hand, the mold body 20 is formed by combining the upper body 30 constituting the upper portion, the lower body 40 constituting the lower and outer portion and the inner body 50 constituting the inner surface. Of course, the mold body 20 is divided into the upper body 30, the lower body 40 and the inner body 50 is configured to facilitate the assembly of the mold body 20 to vary the coupling structure It is also possible (for example, to divide into two component parts).

The upper body 30 constitutes an upper portion of the casting mold and the inner end portion is formed to extend downward by a predetermined length in contact with the inner surface of the inner body 50. This is to allow the end of the extended portion to support the upper surface of the graphite ring 70 to be described later.

On the other hand, in the extended portion of the upper body 30, the gas inlet 32 and the oil inlet path 34 is injected into the gas and oil to supply gas and oil to the upper surface of the graphite ring 70, respectively Is formed.

The lower body 40 is formed in an "L" shape, and constitutes the outer side and the lower portion of the mold body 20, the upper end is in contact with the upper body 30, the other end is in contact with the inner body 50. .

And the lower end of the upper body 30 and the other end inner body 50 of the lower body 40 is coupled. The inner surface of the inner body 50 is formed with a seating portion 52 for seating the graphite ring 70 to be described later. The seating part 52 is formed to correspond to the shape of the outer circumferential surface of the graphite ring 70 so that the outer circumferential surface and the bottom surface of the graphite ring 70 may be seated.

At this time, the upper body 30, the lower body 40 and the inner body 50 are each firmly coupled by screwing. And as shown in Figure 2 by the combination of the upper body 30, the lower body 40 and the inner body 50, the cooling water chamber 60 that can store the cooling water is formed. Here, the size and position of the coolant chamber 60 are related to the position of the graphite ring 70 and will be described later after the graphite ring 70 is described.

The seating part 52 is provided with a porous graphite ring 70. The graphite ring 70 is a portion where the molten metal 80 passing through the mold solidifies with the billet 85. The surface of the molten metal 80 passing through the graphite ring 70 solidifies to form the billet 85. do.

At this time, it is preferable that the outside of the boundary line where the molten metal 80 is solidified to form the billet 85 is formed on the graphite ring 70.

On the other hand, the graphite ring 70 is the outer circumferential surface of the molten metal 80 to solidify the gas and oil introduced through the gas inlet 32 and the oil inlet 34 through the air gap of the graphite ring 70 It is a part which forms a film | membrane so that it may not be in physical contact with this casting mold inner peripheral edge.

The outer circumferential surface and the lower surface of the graphite ring 70 is preferably formed as a curved surface as a part seated on the seating portion 52 of the inner body 50.

The graphite ring 70 is seated on the inner body 50 is shown in FIG. As shown in FIG. 3, the graphite ring 70 also forms a non-circular through hole 10 and is seated on the seating portion 52 of the inner body 50.

As shown in an enlarged view in FIG. 3, the upper end of the graphite ring 70 is supported by the upper body 30, which is not shown, and the supporting force of the upper body 30 and the graphite ring 70 is the upper body. It is generated by the coupling force of the 30 and the inner body 50. A coupling hole 54 for screwing the inner main body 50 and the upper main body 30 is formed at an upper end of the inner main body 50.

In addition, the outer portion of the inner body 50 is a portion where the coolant chamber 60 is formed, and it can be seen that the coolant discharge path 56 through which the coolant flows from the coolant chamber 60 is formed. Here, in the enlarged view in FIG. 3, it can be seen that the intervals of the cooling water discharge paths 56 are different from each other. This means that the density of the cooling water discharge path 56 is different for each part of the inner body. This is because the billet 85 has a non-circular cross-section, and thus the amount of heat generated is different for each part depending on the form, so that the amount of cooling water discharged to exhibit the same cooling effect on all parts of each billet 85. Because it must be different. In other words, in order to control the amount of the cooling water, the number of cooling water discharge holes through which the cooling water is ejected may be differently formed according to the amount of heat generated by the billet 85.

That is, since the angular portion or the corner portion has more heat generation than the flat surface or the curved surface, it is necessary to supply a lot of the cooling water to these portions.

Meanwhile, the graphite ring 70 according to the present invention is divided into a plurality of pieces, as shown in FIG. 4. In the specific embodiment of the present invention will be described by taking an example that the graphite ring 70 is divided into three pieces as shown.

The graphite ring 70 is divided into a plurality of pieces instead of being integrally formed. The graphite ring 70 according to the present invention does not adopt a shrink fit method, which is a fastening method of the conventional graphite ring 70, to mechanical coupling force. As the fastening method is adopted, it is not necessary to maintain the integral type to minimize the deformation of the thermal expansion. That is, although the structure of the divided graphite ring 70 is advantageous to thermal expansion, in the conventional continuous casting mold, since the graphite ring 70 is shrinked and fixed, it has to be integrally formed.

In this case, an asbestos gasket 90 is provided at the contact surface between the upper end of the graphite ring 70 and the upper body 30 to prevent a gap from occurring in these contact surfaces. This is because the gas and oil flowing into the graphite ring 70 from the gas inflow path 32 and the oil inflow path 34 should be prevented from being mixed before entering the graphite ring 70.

On the other hand, the coolant chamber 60 provided in the mold body 20 is to store the coolant supplied to the billet 85, to cool the graphite ring 70 receives a high temperature heat during casting In order to be formed at the same height as the graphite ring 70 on the back of the graphite ring 70.

That is, the height of the graphite ring 70 and the coolant chamber 60, the upper end of the graphite ring 70 is higher than the lower end of the cooling water chamber 60, the lower end of the graphite ring 70 is the cooling water chamber ( 60) is determined to be lower than the top. More preferably, an upper end of the graphite ring 70 is lower than an upper end of the cooling water chamber 60, and a lower end of the graphite ring 70 is higher than a lower end of the cooling water chamber 60, that is, the graphite. The height L of the entire longitudinal direction of the ring 70 is determined to be included in the longitudinal direction l of the coolant chamber 60.

At this time, the inner circumferential surface of the graphite ring 70 may be formed in a tapered shape that becomes wider in a downward direction so as to correspond to the change amount of the billet changed by solidification shrinkage. This is to prevent the billet from being interfered with the graphite ring as it solidifies and shrinks.

On the other hand, the inner peripheral surface of the mold body 20 of the specific embodiment of the present invention is provided with a transfer plate 95 for transferring the molten metal downward. The transfer plate 95 may be provided in the upper portion of the graphite ring 70, and may be formed in a tapered shape in which the width thereof becomes wider in a downward direction corresponding to the amount of solidification shrinkage of the billet.

Hereinafter, the operation of the specific embodiment of the present invention will be described in detail according to the aluminum continuous casting method of the air slip method.

In the aluminum continuous casting method of the air slip method according to a specific embodiment of the present invention, the molten metal 80 is cooled while moving along the through hole 10 of the mold body 20.

Then, when the molten metal 80 reaches the position of the graphite ring 70, the outer side of the molten metal 80 is solidified to form a billet 85. At this time, the boundary line 99 of the billet 85 and the molten metal 80 is as shown in FIG. Of course, the boundary line 99 is a virtual boundary line, and in reality, the boundary between the molten metal 80 and the billet 85 is not clear.

Since the billet 85 is formed at the graphite ring 70, gas and oil are introduced into the graphite ring 70 from the inside of the graphite ring 70 to form a thin film. As the gas, nitrogen and oxygen gas are generally used.

The reason why the film is formed on the inner circumferential surface of the graphite ring 70 is to prevent the molten metal from coming into contact with the graphite ring 70 when it solidifies, thereby roughening the surface.

At this time, the molten metal 80 is squeezed from the inner side to the outer side since the outer portion is cooled first and the inner portion is cooled later. However, since the inner circumferential surface of the graphite ring 70 is formed in a tapered shape, the swelling pressure due to heat disappears with the volume expansion of the molten metal 80.

Meanwhile, the molten metal 80 or the billet 85 heats the graphite ring 70. In this case, the heated graphite ring 70 is cooled by the cooling water of the cooling water chamber 60 formed with the inner body 50 interposed between the rear surface of the graphite ring 70.

In addition, the billet 85 is cooled by the cooling water discharged from the cooling water discharge path 56 formed in the inner body 50 while moving downward through the graphite ring 70. At this time, the heat generation amount of the billet 85 depends on the shape and position of the cross section. Therefore, the location where the calorific value is large is such that the amount of cooling water is greater and the calorific value is less so that the total billet 85 is cooled evenly. If even cooling does not occur in the billet 85, an alloy of a uniform structure cannot be obtained and in severe cases cracks and the like occur.

As described above, adjusting the amount of the coolant may be performed by adjusting the size or controlling the number of the coolant discharge paths 56.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

In the continuous casting mold of the air slip method according to the present invention as described in detail above, the following effects can be expected.

That is, since the graphite ring provided in the casting mold is divided into a plurality of pieces and fixed to the mold main body by mechanical coupling, there is an advantage in that the deformation of the shape is reduced by heat and the risk of detachment from the mold main body is reduced.

In addition, in the present invention, since the cooling water chamber is located on the rear surface of the graphite ring, the graphite ring is cooled by the cooling water of the cooling water chamber, thereby increasing the heat radiation efficiency of the graphite ring.

In the present invention, since oil and gas are supplied to the upper portion of the graphite ring, there is no fear that the graphite ring is removed by the pressure of the oil and the gas, and asbestos gasket is provided at the gas and oil inlet of the graphite ring. There is an advantage that can prevent the occurrence of a gap between the graphite ring and the upper body.

Claims (16)

A mold body in which a non-circular through-hole in which the molten metal moves is formed; A porous graphite ring provided on the inner circumference of the mold main body to supply gas and oil to the surface of the molten metal to be dropped, thereby solidifying the molten metal into a billet; It is provided on the inner circumference of the mold body of the upper portion of the graphite ring, comprising a transfer plate for transferring the molten metal downward; A coolant chamber is formed inside the mold body to store coolant for cooling the billet surface: The coolant chamber is formed on the back of the graphite ring: The non-slip continuous casting mold of the air-slip method, characterized in that the upper end of the graphite ring is connected to the gas inlet and oil inlet for supplying gas and oil into the porous graphite ring through the mold body. The method of claim 1, The coolant chamber, The upper end of the graphite ring is higher than the lower end of the cooling water chamber, the lower end of the graphite ring is a non-slip continuous casting mold of the air slip type, characterized in that formed to a height lower than the upper end of the cooling water chamber. The method of claim 1, The coolant chamber, The upper end of the graphite ring is lower than the upper end of the cooling water chamber, the lower end of the graphite ring is a non-slip continuous casting mold of the air slip type, characterized in that formed to a height higher than the lower end of the cooling water chamber. The method according to any one of claims 1 to 3, The mold body, An upper body configured to form an upper portion of the chamber, one side of which supports a top surface of the graphite ring, and a gas inlet and an oil inlet for supplying gas and oil to the graphite ring; A lower body constituting the lower and outer parts of the mold body; Combined with the upper body and the lower body to form the inner portion of the mold main body, non-slip continuous casting mold of the air slip method characterized in that it comprises an inner body is formed in the seating portion is seated on the graphite ring in the inner edge . The method of claim 4, wherein The graphite ring, An upper surface is supported by the upper body, The non-slip continuous casting mold of the air slip type, characterized in that the side and the lower surface is mounted to the seating portion of the inner body is fixed to the mold body. The method of claim 5, wherein Between the graphite ring and the upper body, Non-slip continuous casting mold of the air slip type, characterized in that the asbestos gasket is provided. The method of claim 6, The graphite ring, Non-slip continuous casting mold of the air slip type, characterized in that divided into a plurality of pieces. The method of claim 7, wherein The inner peripheral surface of the graphite ring, A non-slip continuous casting mold of an air slip type, characterized in that it is formed in a tapered shape that becomes wider in a downward direction so as to correspond to an amount of change of a billet changed by solidification shrinkage. The method of claim 8, The lower body, The non-slip continuous casting mold of the air slip type, characterized in that the cooling water discharge path for supplying the cooling water of the cooling water chamber to the billet is formed. The method of claim 9, The diameter of the cooling water discharge path, According to the calorific value of the billet, non-slip continuous casting mold of the air slip method, characterized in that each is formed differently. The method of claim 9, The cooling water discharge path, According to the calorific value of the billet, non-slip continuous casting mold of the air slip type, characterized in that each of the parts of the inner body is formed with a different density. In the continuous casting method of producing a billet having a non-circular cross-section by melting the solidified while passing through the inner surface of the transfer plate and the graphite ring tapered on the inner surface of the non-circular through-hole of the mold body, Forming a film on the surface of the molten metal in which gas and oil introduced from the upper portion of the graphite ring are solidified; The graphite ring is cooled by the cooling water of the cooling water chamber provided on the back of the graphite ring; An air slip continuous casting method of aluminum alloy, characterized in that the boundary between the solidified billet and the molten metal is in contact with the inner surface of the graphite ring. The method of claim 12, The billet, Air-slip type aluminum alloy continuous casting method characterized in that the cooling is supplied by the cooling water supplied from the cooling water chamber and ejected from the cooling water discharge path of the lower portion of the graphite ring. The method of claim 13, The coolant is Air-slip type aluminum alloy continuous casting method characterized in that the ejected in different amounts according to the amount of heat generated according to the form of the billet. The method of claim 14, The amount of coolant is Air-slip type aluminum alloy continuous casting method characterized in that determined by the number of the discharge path of the cooling water. The method of claim 14, The amount of coolant is Air-slip type aluminum alloy continuous casting method characterized in that determined by the size of the cooling water discharge path.

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