US20150251243A1

US20150251243A1 - Up-drawing continuous casting method

Info

Publication number: US20150251243A1
Application number: US14/638,333
Authority: US
Inventors: Naoaki Sugiura; Yusuke Yokota
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2014-03-10
Filing date: 2015-03-04
Publication date: 2015-09-10
Also published as: CN104907516A; JP2015167989A

Abstract

An up-drawing continuous casting method according to one aspect of the invention is an up-drawing continuous casting method for forming a bent shape in a cast casting by forming the casting in a first direction and then changing an up-drawing direction to a second direction and forming the casting in the second direction. This up-drawing continuous casting method includes drawing up the molten metal in the first direction; and changing the up-drawing direction to a third direction in which an angle between the third direction and the first direction is greater than an angle between the second direction and the first direction, from after a portion that will have the bent shape passes through the molten metal passage portion until the portion that will have the bent shape reaches a solidification interface, and then drawing up the molten metal.

Description

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2014-046047 filed on Mar. 10, 2014 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to an up-drawing continuous casting method.
2. Description of Related Art
Japanese Patent Application Publication No. 2012-61518 (JP 2012-61518 A) proposes a free casting method as a groundbreaking up-drawing continuous casting method that does not require a mold. As described in JP 2012-61518 A, a starter is first dipped into the surface of molten metal (a molten metal surface), and then when the starter is drawn up, molten metal is also drawn up following the starter by surface tension and the surface film of the molten metal. Here, a casting that has a desired sectional shape is able to be continuously cast by drawing up the molten metal through a shape determining member arranged near the molten metal surface, and cooling the drawn up molten metal.
With a normal continuous casting method, the sectional shape and the shape in the longitudinal direction are both determined by a mold. In particular, with a continuous casting method, the solidified metal (i.e., the casting) must pass through the mold, so the cast casting takes on a shape that extends linearly in the longitudinal direction.
In contrast, the shape determining member in the free casting method determines only the sectional shape of the casting. The shape in the longitudinal direction is not determined. Therefore, castings of various shapes in the longitudinal direction are able to be obtained by drawing the starter up while moving the starter (or the shape determining member) in a horizontal direction. For example, JP 2012-61518 A describes a hollow casting (i.e., a pipe) formed in a zigzag shape or a helical shape, not a linear shape in the longitudinal direction.
The inventors discovered the problem described below. With the free casting method described in JP 2012-61518 A, the molten metal drawn up through the shape determining member is cooled and solidified by cooling gas, so a solidification interface is positioned above the shape determining member. Therefore, when forming a bent shape in the casting by changing the up-drawing direction of the molten metal, the molten metal solidifies after the change in the up-drawing direction. Therefore, the molten metal drawn up before the change in the up-drawing direction ends up being drawn to the molten metal drawn up after the change in the up-drawing direction, and as a result, the bent shape ends up becoming rounded. As a result, a bent shape having a predetermined bending angle is unable to be formed in the casting, which is problematic.

SUMMARY OF THE INVENTION

In view of this, the invention aims to provide an up-drawing continuous casting method capable of forming a bent shape having a predetermined angle in a cast casting.
One aspect of the invention relates to an up-drawing continuous casting method for forming a bent shape in a cast casting by forming the casting in a first direction and then changing an up-drawing direction to a second direction and forming the casting in the second direction, the casting being formed by drawing up molten metal held in a holding furnace from a molten metal surface of the molten metal, passing the molten metal through a molten metal passage portion of a shape determining member that determines a sectional shape of the casting, and solidifying the molten metal. This up-drawing continuous casting method includes a step of drawing up the molten metal in the first direction; and a step of changing the up-drawing direction to a third direction in which an angle between the third direction and the first direction is greater than an angle between the second direction and the first direction, from after a portion that will have the bent shape passes through the molten metal passage portion until the portion that will have the bent shape reaches a solidification interface, and then drawing up the molten metal. The up-drawing continuous casting method according to this aspect of the invention changes the up-drawing direction of the molten metal after the portion that will have the bent shape moves close to the solidification interface. Therefore, the majority of the molten metal drawn up before the portion that will have the bent shape is already solidified when the up-drawing direction of the molten metal changes, so a constant shape is able to be maintained without being affected by the molten metal drawn up after the change in the up-drawing direction. As a result, rounding of the bent shape is able to be suppressed. Also, the up-drawing direction is changed to the third direction in which the angle between the third direction and the first direction is greater than the angle between the second direction and the first direction, and then the molten metal is drawn up. Accordingly, the extending direction of the retained molten metal is able to be aligned with the second direction in a short period of time from after the up-drawing direction of the molten metal is changed until the portion that will have the bent shape reaches the solidification interface. As a result, a bent shape having a predetermined bending angle is able to be formed in the casting.
The invention thus makes it possible to provide an up-drawing continuous casting method capable of forming a bent shape having a predetermined angle in a cast casting.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a sectional view showing a frame format of a free casting apparatus according to a first example embodiment of the invention;

FIG. 2 is a plan view of a shape determining member according to the first example embodiment;

FIG. 3 is a sectional view of one example of a molded component of a casting;

FIG. 4 is a view illustrating a free casting method according to the first example embodiment;

FIG. 5 is a view illustrating a casting method of a casting according to related art;

FIG. 6 is a sectional view of another example of a molded component of a casting;

FIG. 7 is a view illustrating a free casting method according to the first example embodiment;

FIG. 8 is a view illustrating a casting method of a casting according to related art;

FIG. 9 is an image showing casting results of the castings;

FIG. 10 is a plan view of a shape determining member according to a second example embodiment of the invention; and

FIG. 11 is a side view of the shape determining member according to the second example embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, specific example embodiments to which the invention has been applied will be described in detail with reference to the accompanying drawings. However, the invention is not limited to these example embodiments. Also, the description and the drawings are simplified as appropriate to clarify the description.

First Example Embodiment

First, a free casting apparatus (up-drawing continuous casting apparatus) according to a first example embodiment of the invention will be described with reference to FIG. 1. FIG. 1 is a sectional view showing a frame format of the free casting apparatus according to the first example embodiment. As shown in FIG. 1, the free casting apparatus according to the first example embodiment includes a molten metal holding furnace 101, a shape determining member 102, a support rod 104, an actuator 105, a cooling gas nozzle 106, a cooling gas supplying portion 107, and an up-drawing machine 108. In FIG. 1, a right-handed xyz coordinate system is shown for descriptive purposes to illustrate the positional relationship of the constituent elements. The x-y plane in FIG. 1 forms a horizontal plane, and the z-axis direction is the vertical direction. More specifically, the plus direction of the z-axis is vertically upward.
The molten metal holding furnace 101 holds molten metal M1 such as aluminum or an aluminum alloy, for example, and keeps it at a predetermined temperature at which the molten metal M1 has fluidity. In the example in FIG. 1, molten metal is not replenished into the molten metal holding furnace 101 during casting, so the surface of the molten metal M1 (i.e., the molten metal surface level) drops as casting proceeds. However, molten metal may also be replenished into the molten metal holding furnace 101 when necessary during casting so that the molten metal surface level is kept constant. Here, the position of a solidification interface SIF can be raised by increasing a set temperature of the molten metal holding furnace 101, and lowered by reducing the set temperature of the molten metal holding furnace 101. Naturally, the molten metal M1 may be another metal or alloy other than aluminum.
The shape determining member 102 is made of ceramic or stainless steel, for example, and is arranged above the molten metal M1. The shape determining member 102 determines the sectional shape of a cast casting M3. The casting M3 shown in FIG. 1 is a solid casting (a plate) having a rectangular cross-section in the horizontal direction (hereinafter, simply referred to as “transverse section”). Naturally, the sectional shape of the casting M3 is not particularly limited. That is, the casting M3 may also be a hollow casting of a round pipe or a square pipe or the like.
In the example in FIG. 1, a main surface (a lower surface) on a lower side of the shape determining member 102 is arranged contacting the molten metal surface. Therefore, an oxide film that forms on the surface of the molten metal M1 and foreign matter floating on the surface of the molten metal M1 are able to be prevented from getting mixed into the casting M3. However, the lower surface of the shape determining member 102 may also be arranged a predetermined distance away from the molten metal surface. When the shape determining member 102 is arranged away from the molten metal surface, heat deformation and erosion of the shape determining member 102 are inhibited, so the durability of the shape determining member 102 improves.
FIG. 2 is a plan view of the shape determining member 102 according to the first example embodiment. Here, the sectional view of the shape determining member 102 in FIG. 1 corresponds to a sectional view taken along line I-I in FIG. 2. As shown in FIG. 2, the shape determining member 102 has a rectangular planar shape, for example, and has a rectangular open portion (a molten metal passage portion 103) having a thickness t1 and a width w1 through which the molten metal passes in the center portion. The xyz coordinates in FIG. 2 match those in FIG. 1.
As shown in FIG. 1, after joining with a starter ST that has been dipped into the molten metal M1, the molten metal M1 is drawn up following the starter ST while maintaining its outer shape, by the surface tension and the surface film of the molten metal M1, and passes through the molten metal passage portion 103 of the shape determining member 102. By passing the molten metal M1 through the molten metal passage portion 103 of the shape determining member 102, external force is applied to the molten metal M1 from the shape determining member 102, such that the sectional shape of the casting M3 is determined. Here, the molten metal that is drawn up from the molten metal surface following the starter ST (or the casting M3 formed by the molten metal M1 drawn up following the starter ST solidifying) by the surface film and the surface tension of the molten metal M1 will be referred to as “retained molten metal M2”. Also, the boundary between the casting M3 and the retained molten metal M2 is a solidification interface SIF.
The support rod 104 supports the shape determining member 102. The support rod 104 is connected to the actuator 105. The shape determining member 102 is able to move up and down (i.e., in the vertical direction; the z-axis direction) via the support rod 104, by the actuator 105. According to this kind of structure, the shape determining member 102 is able to be moved downward as the molten metal surface level drops as casting proceeds.
A cooling gas nozzle (a cooling portion) 106 is cooling means for spraying cooling gas (e.g., air, nitrogen, argon, or the like) supplied from the cooling gas supplying portion 107 at the casting M3 to cool the casting M3. The position of the solidification interface SIF is able to be lowered by increasing the flow rate of the cooling gas, and raised by reducing the flow rate of the cooling gas. The cooling gas nozzle 106 is also able to be moved up and down (i.e., in the vertical direction; in the z-axis direction) and horizontally (i.e., in the x-axis direction and the y-axis direction). Therefore, for example, the cooling gas nozzle 106 can be moved downward, in concert with the movement of the shape determining member 102, as the molten metal surface level drops as casting proceeds.
Alternatively, the cooling gas nozzle 106 can be moved horizontally, in concert with horizontal movement of the up-drawing machine 108.
The casting M3 is formed by the retained molten metal M2 near the solidification interface SIF progressively solidifying from the upper side (i.e., the plus side in the z-axis direction) toward lower side (i.e., the minus side in the z-axis direction), by cooling the starter ST and the casting M3 with the cooling gas, while drawing the casting M3 up with the up-drawing machine 108 that is connected to the starter ST. The position of the solidification interface SIF is able to be raised by increasing the up-drawing speed with the up-drawing machine 108, and lowered by reducing the up-drawing speed. Also, the retained molten metal M2 is able to be drawn up diagonally by drawing the casting M3 up while moving the up-drawing machine 108 horizontally (in the x-axis direction and the y-axis direction). Therefore, the longitudinal shape of the casting M3 is able to be freely changed. The longitudinal shape of the casting M3 may also be freely changed by moving the shape determining member 102 horizontally, instead of by moving the up-drawing machine 108 horizontally.
Continuing on, a free casting method according to the example embodiment will be described with reference to FIG. 1.
First, the starter ST is lowered by the up-drawing machine 108 so that it passes through the molten metal passage portion 103 of the shape determining member 102, and the tip end portion of the starter ST is dipped into the molten metal M1.
Next, the starter ST starts to be drawn up at a predetermined speed. Here, even if the starter ST separates from the molten metal surface, the molten metal M1 follows the starter ST and is drawn up from the molten metal surface by the surface film and surface tension, and forms the retained molten metal M2. As shown in FIG. 1, the retained molten metal M2 is formed in the molten metal passage portion 103 of the shape determining member 102. That is, the shape determining member 102 gives the retained molten metal M2 its shape.
Next, the starter ST (or the casting M3 formed by the retained molten metal M2 solidifying) is cooled by cooling gas blown from the cooling gas nozzle 106. As a result, the retained molten metal M2 is indirectly cooled and solidifies progressively from the upper side toward the lower side, thus forming the casting M3. In this way, the casting M3 is able to be continuously cast.
Here, a bent shape is able to be formed in the casting M3 by changing the up-drawing direction of the molten metal M1. This will be described in detail below.
FIG. 3 is a sectional view of an example of a molded component of the casting M3 cast by the free casting apparatus shown in FIG. 1. The xyz coordinates in FIG. 3 match those in FIG. 1.
With the molded component of the casting M3 shown in FIG. 3, after portions (1 and 2 is in the drawing; hereinafter, also referred to as castings M3_1 and M3_2) of the molded component are formed in the vertical direction (i.e., the z-axis direction; hereinafter referred to as a “first direction”), then other portions (3 and 4 is in the drawing; hereinafter, also referred to also as castings M3_3 and M3_4) of the molded component are formed in a direction (i.e., the z-axis direction; hereinafter, also referred to as a “second direction”) inclined toward the x-axis direction plus side by an angle θ1 with respect to the first direction. Here, a bent shape having a predetermined bending angle a is formed near the boundary between the castings M3_2 and M3_3. The angle θ1 is α supplementary angle to the angle α.
FIG. 4 is a view illustrating the free casting method of the molded component of the casting M3 shown in FIG. 3. The xyz coordinates in FIG. 4 match those in FIG. 1. Hereinafter, a case in which the up-drawing speed and cooling conditions of the molten metal M1 are constant, will be described in order to simplify the description. Therefore, the solidification interface is also constant.
First, the retained molten metal M2 (1 and 2 in the drawing; hereinafter, also referred to as retained molten metals M2_1 and M2_2) that extends in the first direction is progressively formed by continuously drawing up the molten metal M1 in the first direction (time t0 to t2).
Then, by drawing up the molten metal M1 in the first direction, a retained molten metal M2_3 (3 in the drawing) that extends in the first direction is formed after the retained molten metals M2_1 and M2_2 are formed (time t2 to t3). At this time, the retained molten metal M2_1 reaches the solidification interface and thus solidifies, forming the casting M3_1 that extends in the first direction (time t2 to t3). At time t2 to t3, the up-drawing direction of the retained molten metal M2_3 remains the first direction, just like the retained molten metals M2_1 and M2_2. That is, at time t2 to t3, a portion that will have the bent shape (near the boundary between the retained molten metals M2_2 and M2_3) does not have the bent shape. Therefore, the retained molten metal M2_1 is able to solidify without being drawing by the retained molten metals M2_2 and M2_3 and changing shape.
Then, as the portion that will have the bent shape moves close to the solidification interface, the up-drawing direction is changed to a direction (hereinafter, referred to as a “third direction”) inclined toward the x-axis direction plus side by an angle θ2 (θ2>θ1) with respect to the first direction, and the molten metal M1 starts to be drawn up (time t3). In the example in FIG. 4, when the portion that will have the bent shape is positioned midway between the molten metal passage portion 103 and the solidification interface, the up-drawing direction changes from the first direction to the third direction, and the molten metal M1 starts to be drawn up (time t3). As a result, a retained molten metal M2_4 that extends in the third direction (i.e., the region 4 surrounded by the dotted lines in the drawing) is formed (time t3 to t4). Here, the retained molten metal M2_3 formed in the first direction (i.e., the region surrounded by the dotted lines in the drawing) has not yet solidified, and is drawn by the retained molten metal M2_4 formed in the third direction (i.e., the region surrounded by the dotted lines in the drawing), thus changing shape, and being formed extending along a line portion that connects the molten metal passage portion 103 to the solidification interface, together with the retained molten metal M2_4 (i.e., the region surrounded by the solid lines in the drawing). The value of the angle θ2 is set such that the direction in which the portion that will have the bent shape heads toward the solidification interface from the molten metal passage portion 103, i.e., the extending direction of the retained molten metals M2_3 and M2_4, when the portion that will have the bent shape reaches the solidification interface, comes to match the second direction.
Also, at this time, the retained molten metal M2_2 reaches the solidification interface, so it solidifies, forming the casting M3_2 that extends in the first direction (time t3 to t4). Here, as described above, the up-drawing direction of the molten metal M1 is changed after the portion that will have the bent shape moves close to the solidification interface, so the casting M3_1 will of course not be drawn by the retained molten metal M2 and thus will not change shape. What is more, the retained molten metal M2_2 will also solidify either before being drawn by the retained molten metals M2_3 and M2_4 and changing shape, or while that effect is still small. As a result, the desired casting M3_2 that extends in the first direction is able to be formed.
After the portion that will have the bent shape has reached the solidification interface, the up-drawing direction is changed to the second direction, which is the forming direction of the castings M3_3 and M3_4, and the molten metal M1 is drawn up (time t4 to t6). At this time, the retained molten metals M2_3 and M2_4 reach the solidification interface, so they solidifies while maintaining a shape that extends in the second direction, thus forming the castings M3_3 and M3_4.
As a result, a molded component of the casting M3 is able to be formed, the molded component of the casting M3 is formed by the castings M3_1 and M3_2 that extend in the first direction, and the castings M3_3 and M3_4 that extend in the second direction, and molded component of the casting M3 has a bent shape of a predetermined bending angle α.
FIG. 5 is a view illustrating a casting method of the casting M3 according to related art, as a comparative example of FIG. 4. In the example in FIG. 5, the up-drawing direction of the molten metal M1 is changed from the first direction to the second direction at the same time that the portion that will have the bent shape (near the boundary between the retained molten metals M2_2 and M2_3) reaches the molten metal passage portion 103 (time t2). However, the retained molten metal M2 solidifies after the change in the up-drawing direction of the molten metal M1. Therefore, the molten metal drawn up before the change in the up-drawing direction (i.e., the retained molten metals M2_1 and M2_2) will end up being drawn by the molten metal drawn up after the change in the up-drawing direction (i.e., the retained molten metal M2_3), so the bent shape will end up being rounded. As a result, a bent shape having a predetermined angle is unable to be formed in the casting.
In contrast, with the up-drawing continuous casting method according to this example embodiment shown in FIG. 4, the up-drawing direction of the molten metal M1 is changed after the portion that will have the bent shape moves close to the solidification interface. Therefore, the majority (or at least more than that in FIG. 5) of the molten metal M1 drawn up before the portion that will have the bent shape is already solidified when the up-drawing direction of the molten metal M1 changes, so a constant shape is able to be maintained without being affected by the molten metal M1 drawn up after the change in the up-drawing direction. As a result, rounding of the bent shape is able to be suppressed. Also, the up-drawing direction is changed to the third direction in which the angle between the third direction and the first direction is greater than the angle between the second direction and the first direction, and then the molten metal M1 is drawn up. Accordingly, the extending direction of the retained molten metal M2 is able to be aligned with the second direction in a short period of time from after the up-drawing direction of the molten metal M1 is changed until the portion that will have the bent shape reaches the solidification interface. As a result, a bent shape having a predetermined bending angle is able to be formed in the casting M3.
FIG. 6 is a sectional view of another example of a molded component of the casting M3 cast with the free casting apparatus shown in FIG. 1. The xyz coordinates in FIG. 6 match those in FIG. 1.
With the molded component of the casting M3 shown in FIG. 6, portions (castings M3_1 and M3_2) of the molded component are first formed in a direction inclined toward the x-axis direction plus side (hereinafter, simply referred to as the “first direction”) by an angle θ1 with respect to the vertical direction (the z-axis direction; hereinafter simply referred to as the “second direction”), and then other portions (castings M3_3 and M3_4) of the molded component are formed in the second direction. Here, a bent shape having a predetermined bending angle α is formed near the boundary between the castings M3_2 and M3_3.
FIG. 7 is a view illustrating a free casting method of the molded component of the casting M3 shown in FIG. 6. The xyz coordinates in FIG. 7 match those in FIG. 1. The free casting method shown in FIG. 7 is basically the same as the free casting method shown in FIG. 4, except that the orientations of the first direction and the second direction are different, so a description thereof will be omitted. FIG. 8 is a view illustrating a casting method of the casting M3 according to related art, as a comparative example of FIG. 7. FIG. 8 is also basically the same as FIG. 5, except that the orientations of the first direction and the second direction are different, so a description thereof will be omitted.
FIG. 9 is an image of a cross-section of the casting M3 cast according to the free casting method according to this example embodiment. FIG. 9 also shows an image of a cross-section of the casting M3 cast according to the casting method of the related art, as a comparative example. As shown in FIG. 9, it is evident that the bent shape of the casting M3 cast according to the casting method of the related art is rounded, while the bent shape of the casting M3 cast according to the free casting method of this example embodiment is not rounded.
In this way, with the free casting method according to this example embodiment, the up-drawing direction of the molten metal M1 is changed after the portion that will have the bent shape moves close to solidification interface. As a result, the majority of the molten metal M1 drawn up before the portion that will have the bent shape is already solidified when the up-drawing direction of the molten metal M1 changes, so a constant shape is able to be maintained without being affected by the molten metal M1 drawn up after the change in the up-drawing direction. As a result, rounding of the bent shape is able to be suppressed. Also, the up-drawing direction is changed to the third direction in which the angle between the third direction and the first direction is greater than the angle between the second direction and the first direction, and then the molten metal M1 is drawn up. Accordingly, the extending direction of the retained molten metal M2 is able to be aligned with the second direction (i.e., the molding direction of the casting M3) in a short period of time from after the up-drawing direction of the molten metal M1 is changed until the portion that will have the bent shape reaches the solidification interface. As a result, a bent shape having a predetermined bending angle is able to be formed in the casting M3.
In this example embodiment, a case in which the up-drawing direction of the molten metal M1 is changed when the portion that will have the bent shape is positioned midway between the molten metal passage portion 103 and the solidification interface has been described, but the example embodiment is not limited to this. The timing at which the up-drawing direction of the molten metal M1 is changed may any time from after the portion that will have the bent shape passes through the molten metal passage portion 103 until it reaches the solidification interface. However, the value of the angle θ2 must be adjusted such that the direction in which the portion that will have the bent shape heads toward the solidification interface from the molten metal passage portion 103, when the portion that will have the bent shape reaches the solidification interface, comes to match the second direction. For example, a bent shape is able to be made in the casting M3 more accurately the closer the timing at which the up-drawing direction of the molten metal M1 changes is to when the portion that will have the bent shape is near the solidification interface. On the other hand, the change in the up-drawing direction of the molten metal M1 becomes smaller the closer the timing at which the up-drawing direction of the molten metal M1 changes is to when the portion that will have the bent shape is near the molten metal passage portion 103, so the retained molten metal M2 is able to be prevented from being torn or the like by the change in the up-drawing direction. The up-drawing direction of the molten metal M1 is preferably changed when the portion that will have the bent shape is midway between the molten metal passage portion 103 and the solidification interface, or closer to the solidification interface than midway between the molten metal passage portion 103 and the solidification interface.
Also, in this example embodiment, an example in which the up-drawing direction of the molten metal M1 is changed only once to form one bent shape in the casting M3 is described, but the example embodiment is not limited to this. The up-drawing direction of the molten metal M1 may also be changed two or more times to form one bent shape in the casting M3.

Second Example Embodiment

Next, a free casting apparatus according to a second example embodiment of the invention will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view of a shape determining member 202 according to the second example embodiment. FIG. 11 is a side view of the shape determining member 202 according to the second example embodiment. The xyz coordinates in FIGS. 10 and 11 also match those in FIG. 1.
The shape determining member 102 according to the first example embodiment shown in FIG. 2 is made of a single plate, so the thickness t1 and the width w1 of the molten metal passage portion 103 are fixed. In contrast to this, the shape determining member 202 according to the second example embodiment includes four rectangular shape determining plates 202 a, 202 b, 202 c, and 202 d, as shown in FIG. 10. That is, the shape determining member 202 is divided into a plurality of sections. This kind of structure enables the thickness t1 and the width w1 of a molten metal passage portion 203 to be changed. Also, the four rectangular shape determining plates 202 a, 202 b, 202 c, and 202 d are able to move synchronously in the z-axis direction.
As shown in FIG. 10, the shape determining plates 202 a and 202 b are arranged facing each other lined up in the y-axis direction. Also, as shown in FIG. 11, the shape determining plates 202 a and 202 b are arranged at the same height in the z-axis direction. The distance between the shape determining plates 202 a and 202 b determines the width w1 of the molten metal passage portion 203. Also, the shape determining plates 202 a and 202 b are able to move independently in the y-axis direction, so they are able to change the width w1. A laser displacement gauge S1 may be provided on the shape determining plate 202 a, and a laser reflecting plate S2 may be provided on the shape determining plate 202 b, as shown in FIGS. 10 and 11, in order to measure the width w1 of the molten metal passage portion 203.
Also, as shown in FIG. 10, the shape determining plates 202 c and 202 d are arranged facing each other lined up in the x-axis direction. Also, the shape determining plates 202 c and 202 d are arranged at the same height in the z-axis direction. The distance between the shape determining plates 202 c and 202 d determines the thickness t1 of the molten metal passage portion 203. Also, the shape determining plates 202 c and 202 d are able to move independently in the x-axis direction, so they are able to change the thickness t1. The shape determining plates 202 a and 202 b are arranged contacting upper sides of the shape determining plates 202 c and 202 d.
Next, the drive mechanism of the shape determining plate 202 a will be described with reference to FIGS. 10 and 11. As shown in FIGS. 10 and 11, the drive mechanism of the shape determining plate 202 a includes slide tables T1 and T2, linear guides G11, G12, G21, and G22, actuators A1 and A2, and rods R1 and R2. The shape determining plates 202 b, 202 c, and 202 d also each include a drive mechanism, similar to the shape determining plate 202 a, but these are not shown in FIGS. 10 and 11.
As shown in FIGS. 10 and 11, the shape determining plate 202 a is placed on and fixed to the slide table T1 that is able to slide in the y-axis direction. The slide table T1 is slidably placed on the pair of linear guides G11 and G12 that extend parallel to the y-axis direction. Also, the slide table T1 is connected to the rod R1 that extends in the y-axis direction from the actuator A1. This kind of structure enables the shape determining plate 202 a to slide in the y-axis direction.
Also, as shown in FIGS. 10 and 11, the linear guides G11 and G12, and the actuator A1, are placed on and fixed to the slide table T2 that is able to slide in the z-axis direction. The slide table T2 is slidably placed on the pair of linear guides G21 and G22 that extend parallel to the z-axis direction. Also, the slide table T2 is connected to the rod R2 that extends in the z-axis direction from the actuator A2. The linear guides G21 and G22, and the actuator A2, are fixed to a horizontal floor or base, not shown, or the like. This kind of structure enables the shape determining plate 202 a to slide in the z-axis direction. The actuators A1 and A2 may be hydraulic cylinders, air cylinders, or electric motors or the like, for example. The other structure is the same as that of the first example embodiment, so a description thereof will be omitted.
With the free casting method according to the second example embodiment, effects similar to those of the first example embodiment are able to be displayed. In addition, the thickness t1 and width w1 of the molten metal passage portion 203 of the shape determining member 202 are able to be changed. Therefore, the dimensions (the thickness t and the width w) of the casting are able to be freely changed.
The invention is not limited to the example embodiments described above, and may be modified as appropriate without departing from the spirit of the invention.

Claims

What is claimed is:

1. An up-drawing continuous casting method for forming a bent shape in a cast casting by forming the casting in a first direction and then changing an up-drawing direction to a second direction and forming the casting in the second direction, the casting being formed by drawing up molten metal held in a holding furnace from a molten metal surface of the molten metal, passing the molten metal through a molten metal passage portion of a shape determining member that determines a sectional shape of the casting, and solidifying the molten metal, the up-drawing continuous casting method comprising:

drawing up the molten metal in the first direction; and

changing the up-drawing direction to a third direction in which an angle between the third direction and the first direction is greater than an angle between the second direction and the first direction, from after a portion that will have the bent shape passes through the molten metal passage portion until the portion that will have the bent shape reaches a solidification interface, and then drawing up the molten metal.

2. The up-drawing continuous casting method according to claim 1, wherein

the third direction is determined such that a direction in which the portion that will have the bent shape heads toward the solidification interface from the molten metal passage portion, when the portion that will have the bent shape reaches the solidification interface, comes to match the second direction.

3. The up-drawing continuous casting method according to claim 1, further comprising:

changing the up-drawing direction to the second direction and drawing up the molten metal, after the portion that will have the bent shape reaches the solidification interface.

4. The up-drawing continuous casting method according to claim 1, wherein

the up-drawing direction is changed to the third direction and the molten metal is drawn up, when the portion that will have the bent shape is midway between the molten metal passage portion and the solidification interface, or is closer to the solidification interface than midway between the molten metal passage portion and the solidification interface.