The present invention relates to a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method.
In Patent Literature 1, a free casting method is proposed by the present inventors as an epoch-making continuous casting method that does not require a mold. As shown in Patent Literature 1, when a starter is pulled up after it is immersed into the surface of a melted metal (molten metal) (in other words, the molten-metal surface), the molten metal is also drawn out following the starter by the surface film or surface tension of the molten metal. Here, by drawing out the molten metal through a shape-defining member that is located in the vicinity of the molten-metal surface and cooling the molten metal, a cast-metal article with a desired cross-sectional shape can be cast continuously.
In an ordinary continuous casting method, not only the cross-sectional shape but also the longitudinal shape is defined by a mold. In particular, the cast-metal article that is produced by a continuous casting method has a shape that is linearly elongated in its longitudinal direction because the solidified metal (in other words, the cast-metal article) must be passed through a mold.
In contrast, a shape-defining member that is used in a free casting method defines only the cross-sectional shape of the cast-metal article and does not define the longitudinal shape of the cast-metal article. In addition, because the shape-defining member is movable in directions parallel to the molten-metal surface (in other words, horizontal directions), cast-metal articles with different longitudinal shapes can be obtained. For example, a hollow cast-metal article (in other words, a pipe) that is formed to have a zigzag or spiral, not linear, configuration along its length is disclosed in Patent Literature 1.
The present inventors have found the following problem.
According to the free casting method disclosed in Patent Literature 1, it is impossible to accurately control the temperature of the unsolidified molten metal that has been pulled up from the molten-metal surface following the starter (held molten metal). Thus, according to the free casting method disclosed in Patent Literature 1, it is impossible to accurately control the speed at which the starter is pulled up.
The present invention has been made in view of the above circumstances and aims to provide a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method in which the speed at which the starter is pulled up can be accurately controlled by accurately controlling the temperature of the held molten metal.
A pulling-up-type continuous casting apparatus according to one aspect of the present invention includes: a holding furnace that holds a molten metal; a draw-out part that draws out the molten metal from a molten-metal surface of the molten metal that is held in the holding furnace; a shape-defining member that defines a cross-sectional shape of a cast-metal article to be cast by applying an external force to a held molten metal which is an unsolidified molten metal that has been drawn out by the draw-out part, the shape-defining member being located in the vicinity of the molten-metal surface; and a temperature measurement unit that measures the temperature of the held molten metal, in which the temperature of the held molten metal is controlled based on the result of measurement in the temperature measurement unit. According to this structure, the temperature of the held molten metal can be accurately controlled, whereby it is possible to accurately control the speed at which the starter is pulled up.
It is preferable that the temperature measurement unit be a thermocouple and a temperature measuring junction of the temperature measurement unit be provided in the held molten metal.
It is preferable that the temperature measurement unit be a thermocouple and a temperature measuring junction of the temperature measurement unit be provided in the molten metal in the vicinity of the held molten metal.
It is preferable that the temperature measurement unit be a thermocouple and a temperature measuring junction of the temperature measurement unit be provided in the molten metal immediately below the held molten metal.
It is preferable that the temperature measurement unit be a thermocouple and a temperature measuring junction of the temperature measurement unit be provided in the vicinity of a contact surface between the shape-defining member and the held molten metal inside the shape-defining member.
It is preferable that the holding furnace control the temperature of the molten metal based on the result of measurement in the temperature measurement unit to control the temperature of the held molten metal.
It is preferable that the pulling-up-type continuous casting apparatus further include a temperature controller that controls the temperature of the held molten metal based on the result of measurement in the temperature measurement unit.
It is preferable that the temperature controller be provided in the molten metal in the vicinity of the held molten metal.
It is preferable that the temperature controller be provided in the molten metal immediately below the held molten metal.
It is preferable that the temperature controller be formed to surround the molten metal in the vicinity of the held molten metal.
It is preferable that the pulling-up-type continuous casting apparatus further include a separating part that surrounds the molten metal in the vicinity of the held molten metal.
It is preferable that the temperature controller include a protruding part that extends to the inside of the held molten metal.
It is preferable that the temperature controller be provided in the vicinity of a contact surface between the shape-defining member and the held molten metal inside the shape-defining member.
A pulling-up-type continuous casting method according to one aspect of the present invention includes the steps of: placing a shape-defining member that defines a cross-sectional shape of a cast-metal article to be cast in the vicinity of a molten-metal surface of a molten metal that is held in a holding furnace; pulling up the molten metal through the shape-defining member; and measuring the temperature of a held molten metal which is an unsolidified molten metal that has been pulled up; and controlling the temperature of the held molten metal based on the result of the measurement. According to this structure, the temperature of the held molten metal can be accurately controlled, whereby it is possible to accurately control the speed at which the starter is pulled up.
It is preferable that the pulling-up-type continuous casting method include providing a temperature measuring junction of a thermocouple in the held molten metal to measure the temperature of the held molten metal.
It is preferable that the pulling-up-type continuous casting method include providing a temperature measuring junction of a thermocouple in the molten metal in the vicinity of the held molten metal to measure the temperature of the held molten metal.
It is preferable that the pulling-up-type continuous casting method include providing a temperature measuring junction of a thermocouple in the molten metal immediately below the held molten metal to measure the temperature of the held molten metal.
It is preferable that the pulling-up-type continuous casting method include providing a temperature measuring junction of a thermocouple in the vicinity of a contact surface between the shape-defining member and the held molten metal inside the shape-defining member to measure the temperature of the held molten metal.
It is preferable that the pulling-up-type continuous casting method include controlling the temperature of the molten metal by the holding furnace to control the temperature of the held molten metal.
It is preferable that the temperature of the held molten metal be controlled by a temperature controller.
It is preferable that the temperature controller be provided in the molten metal in the vicinity of the held molten metal.
It is preferable that the temperature controller be provided in the molten metal immediately below the held molten metal.
It is preferable that the temperature controller be formed to surround the molten metal in the vicinity of the held molten metal.
It is preferable that a separating part that surrounds the molten metal in the vicinity of the held molten metal be further provided.
It is preferable that a protruding part extending to the inside of the held molten metal be provided in the temperature controller.
It is preferable that the temperature controller be provided in the vicinity of a contact surface between the shape-defining member and the held molten metal in the shape-defining member.
According to the present invention, it is possible to provide a pulling-up-type continuous casting apparatus and a pulling-up-type continuous casting method in which the speed at which the starter is pulled up can be accurately controlled by accurately controlling the temperature of the held molten metal.
Description is hereinafter made of specific embodiments to which the present invention is applied with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments. The following description and the drawings are simplified as needed to clarify the description.
First, with reference to
The molten metal holding furnace 101 holds a molten metal M1 of aluminum or an aluminum alloy, for example, and maintains the molten metal M1 at a prescribed temperature. In particular, in this embodiment, a case in which the molten metal holding furnace 101 holds the molten metal M1 at a temperature according to a result of measurement in the thermocouple 108 will be described as an example (described later). In the example that is shown in
The internal shape-defining member 102a and the external shape-defining member 102b are made of ceramic or stainless steel, for example, and are located in the vicinity of the molten-metal surface. In the example shown in
The internal shape-defining member 102a defines the internal shape of a cast metal M3 (or a cast-metal article M3) to be cast and the external shape-defining member 102b defines the external shape of the cast metal M3 to be cast. The cast metal M3 shown in
The draw-out part 107 includes a starter (draw-out member) ST that is immersed into the molten metal M1, and a lifter PL (not shown) that drives the starter ST in, for example, vertical directions.
As shown in
The starter ST is made of ceramic or stainless steel, for example. The surfaces of the starter ST may be covered with a protective coating (not shown), such as that of a salt crystal. In this case, because melt-bonding between the starter ST and the molten metal M1 can be prevented, the releasability between the starter ST and the cast metal M3 can be improved. This makes it possible to reuse the starter ST. In addition, the starter ST may have irregular surfaces. In this case, because the protective coating can be easily deposited (precipitated) on the surfaces of the starter ST, the releasability between the starter ST and the cast metal M3 can be further improved. At the same time, the binding force in the pull-up direction between the starter ST and the molten metal M1 during the draw-out of the molten metal can be improved.
The supporting rod 103 supports the internal shape-defining member 102a and the supporting rod 104 supports the external shape-defining member 102b. The positional relation between the internal shape-defining member 102a and the external shape-defining member 102b can be maintained by the supporting rods 103 and 104. By forming the supporting rod 103 having a pipe structure, causing cooling gas to flow through the supporting rod 103, and further providing a blow-out hole in the internal shape-defining member 102a, the cast metal M3 can be cooled from inside as well.
Both the supporting rods 103 and 104 are coupled to the actuator 105. The actuator 105 allows the supporting rods 103 and 104 to move up and down (in vertical directions) and in horizontal directions while keeping the positional relation between the internal shape-defining member 102a and the external shape-defining member 102b. According to this structure, the actuator 105 can move the internal shape-defining member 102a and the external shape-defining member 102b downward when the molten-metal surface level is lowered as the casting proceeds. In addition, because the actuator 105 can move the internal shape-defining member 102a and the external shape-defining member 102b in horizontal directions, the longitudinal shape of the cast metal M3 can be changed freely.
The cooling gas nozzle (cooling part) 106 is used to blow cooling gas (e.g., air, nitrogen, argon) onto the starter ST and the cast metal M3 to cool the starter ST and the cast metal M3. By cooling the starter ST and the cast metal M3 with the cooling gas while the cast metal M3 is being pulled up by the lifter PL (not shown) that has been coupled to the starter ST, the held molten metal M2 in the vicinity of the solidification interface is sequentially solidified and the cast metal M3 is formed continuously.
The thermocouple 108 is used to measure the temperature of the held molten metal M2. In the example shown in
The molten metal holding furnace 101 controls the temperature of the molten metal M1 based on the result of measurement in the thermocouple 108 as described above. According to this structure, the temperature of the held molten metal M2 is accurately controlled. As a result, for example, the temperature of the held molten metal M2 can be reduced to about a melting point, whereby it is possible to improve the speed at which the starter ST is pulled up (that is, to accurately control the speed at which the starter ST is pulled up).
Next, with reference to
First, the starter ST is moved downward and immersed into the molten metal M1 through the molten metal passing part 102c which is between the internal shape-defining member 102a and the external shape-defining member 102b.
Then, the starter ST starts to be pulled up at a prescribed speed. Here, even after the starter ST is separated from the molten-metal surface, the molten metal M1 is pulled up (drawn out) from the molten-metal surface following the starter ST by the surface film or surface tension thereof and forms a held molten metal M2. As shown in
Next, the starter ST (and the cast metal M3) are cooled by the cooling gas blown out of the cooling gas nozzle 106. As a result, the held molten metal M2 is sequentially solidified from top to bottom and the cast metal M3 grows. In this way, the cast metal M3 can be cast continuously.
While casting is being carried out, the thermocouple 108 measures the temperature of the held molten metal M2. The molten metal holding furnace 101 controls the temperature of the molten metal M1 based on the result of measurement in the thermocouple 108. According to this structure, the temperature of the held molten metal M2 is accurately controlled. As a result, for example, the temperature of the held molten metal M2 can be lowered to about the melting point, whereby it is possible to improve the speed at which the starter ST is pulled up (that is, to accurately control the speed at which the starter ST is pulled up).
As described above, the free casting apparatus according to this embodiment includes the thermocouple 108 that measures the temperature of the held molten metal M2 and accurately controls the temperature of the held molten metal M2 based on the result of measurement in the thermocouple 108. According to this structure, the free casting apparatus according to this embodiment is able to lower the temperature of the held molten metal M2 to about the melting point, whereby it is possible to improve the speed at which the starter ST is pulled up (that is, to accurately control the speed at which the starter ST is pulled up).
While the case in which the temperature of the held molten metal M2 is constantly measured while the casting is being carried out has been described in the above embodiment, the present invention is not limited to this case. The temperature of the held molten metal M2 may not be measured, for example, after the speed at which the starter ST is pulled up is determined. Accordingly, for example, the temperature measuring junction of the thermocouple 108 may be provided inside the held molten metal M2 or in the vicinity of the held molten metal M2 with the start of the casting and may be removed after the speed at which the starter ST is pulled up is determined.
The temperature controller 109 is provided in the molten metal M1 which is in the vicinity of the held molten metal M2 or is immediately below the held molten metal M2 and controls the temperature of the molten metal M1 which is in the vicinity of the held molten metal M2 or is immediately below the held molten metal M2 based on the result of measurement in the thermocouple 108. For example, the temperature controller 109 heats the molten metal M1 by a heater or the like or cools the molten metal M1 by causing refrigerant to flow through a refrigerant circuit. According to this structure, it is possible to control the temperature of the held molten metal M2 with higher accuracy.
Since the other structures of the free casting apparatus shown in
More specifically, in the example shown in
According to this structure, the temperature of the held molten metal M2 can be controlled with further accuracy.
More specifically, in the example shown in
According to the above structure, it is possible to directly control the temperature of the held molten metal M2 (to control the temperature of the held molten metal M2 further accurately).
As described above, the free casting apparatus according to this embodiment includes the thermocouple 108 that measures the temperature of the held molten metal M2 and the temperature controller 109 that controls the temperature of the held molten metal M2 based on the result of measurement in the thermocouple 108. Accordingly, the free casting apparatus according to this embodiment is able to control the temperature of the held molten metal M2 further accurately, whereby it is possible to further improve the speed at which the starter ST is pulled up (that is, to control the speed at which the starter ST is pulled up further accurately).
In this embodiment, another configuration example of the free casting apparatus according to the present invention will be described.
As described above, the free casting apparatus according to the first to third embodiments above includes the thermocouple 108 that measures the temperature of the held molten metal M2 and the temperature controller 109 (or the molten metal holding furnace 101) that controls the temperature of the held molten metal M2 based on the result of measurement in the thermocouple 108. Accordingly, the free casting apparatus according to the first to third embodiments is able to accurately control the temperature of the held molten metal M2, whereby it is possible to improve the speed at which the starter ST is pulled up (that is, to accurately control the speed at which the starter ST is pulled up).
While the case in which the cast-metal article having a cylindrical shape (hollow cast-metal article) is formed has been described as an example in the above embodiments, the present invention is not limited thereto. The present invention is also applicable to a case in which a cast-metal article with a shape of a circular column is formed as shown in
Note that the present invention is not limited to the above embodiments and may be changed as needed without departing from its scope. For example, the above-mentioned configuration examples may be used in combination.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/002456 | 4/10/2013 | WO | 00 |