JP5849926B2 - Pull-up type continuous casting apparatus and pull-up type continuous casting method - Google Patents

Description

  The present invention relates to an up-drawing continuous casting apparatus and an up-drawing continuous casting method.

  In Patent Document 1, the inventors have proposed a free casting method as an innovative continuous casting method that does not require a mold. As shown in Patent Document 1, when a starter is brought into contact with the surface of molten metal (molten metal) (that is, the molten metal surface) and then the starter is pulled up, the molten metal is also derived following the starter. Here, a casting having a desired cross-sectional shape can be continuously cast by deriving and cooling the molten metal through a shape determining member installed in the vicinity of the molten metal surface.

In a normal continuous casting method, the shape in the longitudinal direction is defined along with the cross-sectional shape by the mold. In particular, in the continuous casting method, since the solidified metal (that is, the casting) needs to pass through the mold, the cast casting has a shape extending linearly in the longitudinal direction.
On the other hand, the shape defining member in the free casting method defines only the cross-sectional shape of the casting, and does not define the shape in the longitudinal direction. And since a shape prescription | regulation member can move to the direction (namely, horizontal direction) parallel to a molten metal surface, the casting in which the shape of a longitudinal direction is various is obtained. For example, Patent Document 1 discloses a hollow casting (that is, a pipe) that is formed in a zigzag shape or a spiral shape instead of being linear in the longitudinal direction.

JP 2012-61518 A

The inventor has found the following problems.
In the example of the free casting method described in Patent Document 1, the molten metal is an aluminum alloy, and the starter is made of steel having a melting point higher than that of the aluminum alloy. Therefore, it takes a long time after the starter is brought into contact with the molten metal until the starter and the molten metal are combined (coupled) and the molten metal can be derived. As a result, the free casting method described in Patent Document 1 has a problem that the temperature of the molten metal in the crucible (holding furnace) is lowered, so that a highly accurate casting cannot be cast.

  The present invention has been made in view of the above, and a pull-up type continuous casting apparatus and a pull-up type capable of casting a high-precision casting by suppressing a decrease in the temperature of the molten metal in the holding furnace. An object is to provide a continuous casting method.

  The up-drawing continuous casting apparatus according to an aspect of the present invention includes a holding furnace that holds a molten aluminum or an alloy thereof, and a lead-out unit that leads the molten metal from the molten metal surface held in the holding furnace, A shape-defining member that defines the cross-sectional shape of a casting to be cast by passing through the molten metal that is installed in the vicinity of the molten-metal surface and led out by the lead-out portion, and cooling that cools the molten metal that has passed through the shape-defining member The lead-out part has a lead-out member that contacts the molten metal and a drive part that drives the lead-out member, and the lead-out member is made of cast iron. As a result, the time from when the lead member (starter) is brought into contact with the molten metal until the lead member and the molten metal are combined (coupled) and the molten metal can be led out is shortened, and the molten metal in the holding furnace is reduced. Therefore, it is possible to cast a highly accurate casting.

  The composition of the cast iron constituting the lead-out member is such that C is 2.0% by mass or more and 4.2% by mass or less, Si is 1.7% by mass or more and 4.3% by mass or less, and Mn is less than 0.9% by mass. , P is preferably less than 0.2% by mass, S is less than 0.2% by mass, and the rest is Fe.

  It is preferable to further include a heating unit that heats the lead-out member. As a result, the time from when the lead-out member is brought into contact with the molten metal until the lead-out member and the molten metal are combined and the molten metal can be led out is further shortened, and the temperature of the molten metal in the holding furnace is reduced. Since it can be further suppressed, a casting with higher accuracy can be cast.

  It is preferable that the lead-out member is heated by the heating unit at 500 ° C. or less and within 30 minutes. Thereby, the oxide film formed on the surface of the lead member can be reduced, and the lead member and the molten metal can be easily combined.

  It is preferable to further include an oxide film removing unit that removes a surface oxide film of the lead member by air blowing toward the lead member heated by the heating unit. Thereby, since the oxide film formed on the surface of the lead-out member can be removed, the lead-out member and the molten metal can be more easily combined.

  The pulling-up-type continuous casting method according to one aspect of the present invention includes a step of bringing a lead-out member into contact with a molten metal surface of aluminum or an alloy thereof held in a holding furnace, and deriving the molten metal by the lead-out member, A step of passing a shape defining member that defines a cross-sectional shape of a casting to be cast; and a step of cooling the molten metal that has passed through the shape defining member, wherein the lead-out member is made of cast iron. As a result, the time from when the lead member (starter) is brought into contact with the molten metal until the lead member and the molten metal are combined (coupled) and the molten metal can be led out is shortened, and the molten metal in the holding furnace is reduced. Therefore, it is possible to cast a highly accurate casting.

  The composition of the cast iron constituting the lead-out member is such that C is 2.0% by mass or more and 4.2% by mass or less, Si is 1.7% by mass or more and 4.3% by mass or less, and Mn is less than 0.9% by mass. , P is preferably less than 0.2% by mass, S is less than 0.2% by mass, and the rest is Fe.

  It is preferable that the method further includes heating the lead-out member before bringing the lead-out member into contact with the molten metal surface. As a result, the time from when the lead-out member is brought into contact with the molten metal until the lead-out member and the molten metal are combined and the molten metal can be led out is further shortened, and the temperature of the molten metal in the holding furnace is reduced. Since it can be further suppressed, a casting with higher accuracy can be cast.

  It is preferable to heat the lead-out member at 500 ° C. or less and within 30 minutes. Thereby, the oxide film formed on the surface of the lead member can be reduced, and the lead member and the molten metal can be easily combined.

  It is preferable that the method further includes a step of removing the surface oxide film of the lead-out member by air blowing toward the heated lead-out member. Thereby, since the oxide film formed on the surface of the lead-out member can be removed, the lead-out member and the molten metal can be more easily combined.

  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 capable of casting a casting with high accuracy by suppressing a decrease in the temperature of the molten metal in the holding furnace.

1 is a cross-sectional view of a free casting apparatus according to Embodiment 1. FIG. It is a top view of the internal shape defining member 102a and the external shape defining member 102b. It is a figure which shows the relationship between the heating temperature of starter ST, and the thickness of a surface oxide film. It is a figure which shows the relationship between the heating time of starter ST, and the thickness of a surface oxide film. It is a cross-sectional photograph which shows starter ST after a heating. It is a figure which shows the relationship between the material of starter ST, and the temperature fall degree of a molten metal. It is a figure which shows the relationship between the material of starter ST, and the thickness dispersion | variation in the casting cast.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
First, with reference to FIG. 1, the free casting apparatus (pull-up type continuous casting apparatus) according to Embodiment 1 will be described. 1 is a cross-sectional view of a free casting apparatus according to Embodiment 1. FIG. As shown in FIG. 1, the free casting apparatus according to Embodiment 1 includes a molten metal holding furnace 101, an internal shape defining member 102a, an external shape defining member 102b, support rods 103 and 104, an actuator 105, a cooling gas nozzle 106, and A starter ST is provided.

  The molten metal holding furnace 101 accommodates a molten metal M1 of aluminum or its alloy and holds it at a predetermined temperature. In the example of FIG. 1, since the molten metal is not replenished to the molten metal holding furnace 101 during casting, the surface of the molten metal M1 (that is, the molten metal surface) decreases as the casting progresses. On the other hand, the molten metal may be replenished to the molten metal holding furnace 101 at any time during casting to keep the molten metal surface constant. In the present embodiment, a case where the molten metal M1 is an aluminum alloy will be described as an example.

  The internal shape defining member 102a and the external shape defining member 102b are made of, for example, ceramics or stainless steel, and are disposed in the vicinity of the molten metal surface. In the example of FIG. 1, the inner shape defining member 102a and the outer shape defining member 102b are arranged so as to contact the molten metal surface. However, the inner shape defining member 102a and the outer shape defining member 102b may be installed such that their main surfaces on the lower side (the hot water surface side) do not contact the hot water surface. Specifically, a predetermined gap (for example, about 0.5 mm) may be provided between the main surface on the lower side of the inner shape defining member 102a and the outer shape defining member 102b and the molten metal surface.

  The internal shape defining member 102a defines the internal shape of the casting M3 to be cast, and the external shape defining member 102b defines the external shape of the cast M3 to be cast. The casting M3 shown in FIG. 1 is a hollow casting (that is, a pipe) having a horizontal cross section (hereinafter referred to as a transverse section) having a tubular shape. Specifically, the inner shape defining member 102a defines the inner diameter of the cross section of the casting M3, and the outer shape defining member 102b defines the outer diameter of the cross section of the casting M3.

  FIG. 2 is a plan view of the inner shape defining member 102a and the outer shape defining member 102b. Here, the cross-sectional views of the internal shape determining member 102a and the external shape determining member 102b in FIG. 1 correspond to the II cross-sectional view in FIG. As shown in FIG. 2, the external shape defining member 102b has, for example, a rectangular planar shape, and has a circular opening at the center. The internal shape defining member 102a has a circular planar shape and is disposed at the center of the opening of the external shape defining member 102b. A gap between the inner shape determining member 102a and the outer shape determining member 102b becomes a molten metal passage portion 102c through which the molten metal passes. As described above, the shape defining member 102 includes the inner shape defining member 102a, the external shape defining member 102b, and the molten metal passage portion 102c.

  As shown in FIG. 1, after the molten metal M1 is combined (coupled) with the starter (leading member) ST, the molten metal M1 is pulled up following the starter ST while maintaining its outer shape by its surface film and surface tension, and the molten metal passage portion 102c. Pass through. Here, the molten metal pulled up from the molten metal surface following the starter ST (or the casting M3 formed by solidification of the molten metal M1 derived by the starter ST) by the surface film or surface tension of the molten metal is retained with the molten metal M2. Call. Further, the interface between the casting M3 and the retained molten metal M2 is a solidification interface.

  The support rod 103 supports the internal shape defining member 102a, and the support rod 104 supports the external shape defining member 102b. The support rods 103 and 104 can maintain the positional relationship between the internal shape defining member 102a and the external shape defining member 102b. Here, if the support rod 103 has a pipe structure, a cooling gas is allowed to flow therethrough, and a blow hole is provided in the internal shape defining member 102a, the casting M3 can be cooled also from the inside.

  Both support rods 103 and 104 are connected to the actuator 105. By the actuator 105, the support rods 103 and 104 can move in the vertical direction (vertical direction) and the horizontal direction while maintaining the positional relationship between the internal shape defining member 102a and the external shape defining member 102b. With such a configuration, the inner shape defining member 102a and the outer shape defining member 102b can be moved downward as the molten metal surface is lowered due to the progress of casting. Further, since the inner shape defining member 102a and the outer shape defining member 102b can be moved in the horizontal direction, the shape of the casting M3 in the longitudinal direction can be freely changed.

  The cooling gas nozzle (cooling unit) 106 is for blowing a cooling gas (air, nitrogen, argon, etc.) on the starter ST or the casting M3 to cool it. The molten metal M2 in the vicinity of the solidification interface is sequentially solidified by continuously cooling the starter ST and the casting M3 with the cooling gas while pulling up the casting M3 by a pulling machine (drive unit; not shown) connected to the starter ST. Thus, the casting M3 is formed. The starter ST and the pulling machine are also referred to as a derivation unit.

  Here, the starter ST is made of cast iron. The composition of the cast iron constituting the starter ST is as follows: C is 2.0% by mass or more and 4.2% by mass or less, Si is 1.7% by mass or more and 4.3% by mass or less, and Mn is less than 0.9% by mass. , P is less than 0.2% by mass, S is less than 0.2% by mass, and the rest is Fe.

  The starter ST made of cast iron has a lower melting point than that of a starter made of high-melting steel, and therefore easily combines (bonds) with the molten aluminum alloy M1. Therefore, the time from when the starter ST is brought into contact with the molten metal M1 until the starter ST and the molten metal M1 are combined (coupled) and the molten metal M1 can be derived is shortened. Thereby, since the fall of the temperature of the molten metal in a holding furnace is suppressed, highly accurate casting can be performed.

  In addition, when starter ST is comprised with the same aluminum alloy as molten metal M1, the said starter ST and molten metal M1 combine rapidly. However, since the starter ST has a low melting point similar to the molten metal M1, it may be deformed. Thereby, the thickness variation of the casting M3 to be cast may be increased. That is, there is a possibility that casting with high accuracy cannot be performed. On the other hand, when the starter ST is made of cast iron as in the present embodiment, such a problem does not occur.

  Next, the free casting method according to Embodiment 1 will be described.

  First, the starter ST is lowered, and the tip of the starter ST is brought into contact with the molten metal surface of the molten metal M1 through the molten metal passage portion 102c between the internal shape defining member 102a and the external shape defining member 102b.

  After elapse of a predetermined period in which the starter ST and the molten metal M1 are combined (bonded), the starter ST is started to be pulled up at a predetermined speed. Here, even if the starter ST is separated from the molten metal surface, the molten metal M1 is pulled up (derived) from the molten metal surface by the surface film or surface tension to form the retained molten metal M2. As shown in FIG. 1, the retained molten metal M2 is formed in the molten metal passage portion 102c between the inner shape defining member 102a and the outer shape defining member 102b. That is, the shape is imparted to the retained molten metal M2 by the inner shape defining member 102a and the outer shape defining member 102b.

  Next, the starter ST (and the casting M3) is cooled by the cooling gas blown out from the cooling gas nozzle 106. Thereby, the retained molten metal M2 is solidified in order from the upper side to the lower side, and the casting M3 grows. In this way, the casting M3 can be continuously cast.

  Thus, in the free casting apparatus according to the present embodiment, since the starter ST is made of cast iron having a melting point lower than that of steel, it is easy to combine (bond) with the molten metal M1 of aluminum or its alloy. Therefore, in the free casting apparatus according to the present embodiment, the time from when the starter ST is brought into contact with the molten metal M1 until the starter ST and the molten metal M1 are combined (coupled) to be able to derive the molten metal M1. It can be shortened. Thereby, since the free casting apparatus concerning this Embodiment can suppress the fall of the temperature of the molten metal in a holding furnace, it can cast a highly accurate casting.

  Furthermore, in the free casting apparatus according to the present embodiment, the starter ST is made of cast iron having a melting point higher than that of the molten metal M1 of aluminum or its alloy, so that it is difficult to deform. Therefore, the free casting apparatus according to the present embodiment can suppress variations in the thickness of the casting M3 to be cast.

<First Modification of Free Casting Device>
The free casting apparatus according to the present embodiment may further include a heating unit that heats starter ST. Alternatively, this heating unit may be separately provided outside the free casting apparatus.

  The heating unit heats the starter ST before bringing the starter ST into contact with the molten metal M1. Thereby, the time from when the starter ST is brought into contact with the molten metal M1 until the starter ST and the molten metal M1 are combined and the molten metal M1 can be derived is further shortened. Thereby, since the fall of the temperature of the molten metal in a holding furnace is further suppressed, the production | generation of the casting M3 with higher precision is attained.

  The starter ST is preferably heated by the heating unit at 500 ° C. or less and within 30 minutes. Thereby, the oxide film formed on the surface of the starter ST can be reduced, and the starter ST and the molten metal M1 can be easily combined.

  FIG. 3 is a diagram showing the relationship between the heating temperature of the starter ST and the thickness of the oxide film formed on the surface of the starter ST. In the example of FIG. 3, the heating time of the starter ST is 30 minutes.

  As shown in FIG. 3, the thickness of the oxide film increases as the heating temperature increases. In particular, when the heating temperature exceeds 500 ° C., the thickness of the oxide film exceeds 3 μm, and it becomes difficult to combine the starter ST and the molten metal M1. Therefore, the heating temperature of the starter ST is preferably 500 ° C. or lower.

  FIG. 4 is a diagram showing the relationship between the heating time of the starter ST and the thickness of the oxide film formed on the surface of the starter ST. In the example of FIG. 4, the heating temperature of the starter ST is 530 ° C.

  As shown in FIG. 4, the longer the heating time, the thicker the oxide film. In particular, when the heating time exceeds 30 minutes, the thickness of the oxide film exceeds 3 μm, and it becomes difficult to combine the starter ST and the molten metal M1. Accordingly, the heating time of the starter ST is preferably within 30 minutes.

<Second Modification of Free Casting Device>
The free casting apparatus according to the present embodiment may further include an oxide film removing unit that blows air toward the heated starter ST in addition to the heating unit that heats the starter ST. Alternatively, the heating unit and the oxide film removing unit may be separately provided outside the free casting apparatus.

  The oxide film removing unit removes the surface oxide film of the starter ST by air blowing toward the starter ST heated by the heating unit. Here, as described above, if the starter ST is heated at 500 ° C. or less and within 30 minutes, the oxide film formed on the surface of the starter ST becomes as thin as 3 μm or less. As a result, the oxide film removing unit can easily remove the surface oxide film of the starter ST.

  FIG. 5 is a cross-sectional photograph showing the starter ST after heating. In the example shown in FIG. 5, the starter ST made of cast iron is heated at 500 ° C. for 30 minutes.

  As shown in FIG. 5, if the starter ST is heated at 500 ° C. or less within 30 minutes, the oxide film formed on the surface of the starter ST becomes brittle. As a result, the oxide film removing unit can easily remove the surface oxide film of the starter ST.

  Subsequently, the effect of the free casting apparatus according to the present embodiment will be described in more detail with reference to FIGS. 6 and 7.

  FIG. 6 is a diagram illustrating a relationship between the material of the starter ST and the temperature decrease degree of the molten metal M1 in the vicinity of the starter ST. In the example of FIG. 6, the temperature decrease degree of each molten metal M1 when the material of the starter ST is cast iron, cast iron from which the surface oxide film is removed, steel, and aluminum alloy is shown. The composition of cast iron is as follows: C is 3.0 mass%, Si is 2.0 mass%, Mn is less than 0.9 mass%, P is less than 0.2 mass%, S is less than 0.20 mass%, The rest is Fe. As for the composition of steel, C is less than 0.15% by mass, Si is less than 1.0% by mass, Mn is less than 2% by mass, and the rest is Fe. The composition of the aluminum alloy is as follows: Cu is 0.3% by mass, Si is 6.5% by mass, Mg is 0.3% by mass, Zn is less than 0.5% by mass, Fe is less than 0.5% by mass, and Mn is 0.3% by mass and the balance is Al. Moreover, in the example of FIG. 6, the molten metal M1 of an aluminum alloy shows 700 degreeC.

  As shown in FIG. 6, the temperature decrease degree of the molten metal M1 when the cast iron starter ST is used is approximately the same as the temperature decrease degree of the molten metal M1 when the aluminum alloy starter ST is used. It is smaller than the temperature drop degree of the molten metal M1 when the steel starter ST is used. If the surface oxide film is removed, the temperature decrease degree of the molten metal M1 is further reduced.

  FIG. 7 is a diagram showing the relationship between the material of the starter ST and the thickness variation of the casting M3 to be cast. In the example of FIG. 7, when the material of the starter ST is cast iron, cast iron from which the surface oxide film is removed, steel, and aluminum alloy, the thickness variation of the casting M3 cast is shown. In addition, about each composition of cast iron, steel, and an aluminum alloy, since it is the same as that of the case of FIG. 6, the description is abbreviate | omitted.

  As shown in FIG. 7, the thickness variation of the casting M3 when the cast iron starter ST is used is equivalent to the thickness variation of the casting M3 when the steel starter ST is used. This is smaller than the thickness variation of the casting M3 when the alloy starter ST is used.

  That is, when the cast iron starter ST is used, the temperature drop of the molten metal M1 can be suppressed to the same extent as the aluminum alloy starter ST, and the thickness variation of the casting M3 can be suppressed to the same extent as the steel starter ST. It is done.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 101 Molten metal holding furnace 102 Shape defining member 102a Internal shape defining member 102b External shape defining member 102c Melt passage 103, 104 Support rod 105 Actuator 106 Cooling gas nozzle M1 Molten metal M2 Molten metal M3 Cast ST Starter

Claims (10)

A holding furnace for holding a molten aluminum or an alloy thereof;
A lead-out portion for leading out the molten metal from the surface of the molten metal held in the holding furnace;
A shape defining member that defines the cross-sectional shape of a casting to be cast by passing through the molten metal that is installed in the vicinity of the molten metal surface and led out by the lead-out part,
A cooling unit for cooling the molten metal that has passed through the shape defining member,
The derivation unit includes:
A lead-out member in contact with the molten metal;
A drive unit for driving the lead-out member,
The pulling-up-type continuous casting apparatus, wherein the lead-out member is made of cast iron.   The composition of the cast iron constituting the lead-out member is such that C is 2.0% by mass or more and 4.2% by mass or less, Si is 1.7% by mass or more and 4.3% by mass or less, and Mn is less than 0.9% by mass. The pulling-up-type continuous casting apparatus according to claim 1, wherein P is less than 0.2% by mass, S is less than 0.2% by mass, and the rest is Fe.   The pulling-up-type continuous casting apparatus according to claim 1, further comprising a heating unit that heats the lead-out member.   The pulling-up-type continuous casting apparatus according to claim 3, wherein the lead-out member is heated by the heating unit at 500 ° C. or less within 30 minutes.   5. The pulling-up-type continuous casting apparatus according to claim 3, further comprising an oxide film removing unit that removes a surface oxide film of the lead member by blowing air toward the lead member heated by the heating unit. Bringing the lead-out member into contact with the molten metal surface of aluminum or its alloy held in a holding furnace;
Deriving the molten metal by the deriving member and passing the shape defining member defining the cross-sectional shape of the casting to be cast; and
Cooling the molten metal that has passed through the shape defining member, and
The pulling-up-type continuous casting method, wherein the lead-out member is made of cast iron.   The composition of the cast iron constituting the lead-out member is such that C is 2.0% by mass or more and 4.2% by mass or less, Si is 1.7% by mass or more and 4.3% by mass or less, and Mn is less than 0.9% by mass. The pulling-up-type continuous casting method according to claim 6, wherein P is less than 0.2 mass%, S is less than 0.2 mass%, and the rest is Fe.   The pulling-up-type continuous casting method according to claim 6 or 7, further comprising a step of heating the lead-out member before bringing the lead-out member into contact with the molten metal surface.   The pulling-up-type continuous casting method according to claim 8, wherein the lead-out member is heated at 500 ° C. or less within 30 minutes.   The pulling-up-type continuous casting method according to claim 8, further comprising a step of removing a surface oxide film of the lead-out member by air blowing toward the heated lead-out member.