US20090139685A1

US20090139685A1 - Continuous casting apparatus and continuous casting method

Info

Publication number: US20090139685A1
Application number: US12/260,525
Authority: US
Inventors: Kanji Hayashi; Kiyoshi Kagehira; Tatsunori Sugimoto; Hideaki Takatani; Hideaki Furumoto
Original assignee: Mitsubishi Hitachi Metals Machinery Inc
Current assignee: Primetals Technologies Holdings Ltd
Priority date: 2007-11-21
Filing date: 2008-10-29
Publication date: 2009-06-04
Also published as: JP2009125754A; DE102008057818A1

Abstract

A continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

- the continuous casting apparatus comprising, on a side of at least one of the drums:
- a base portion;
- an arm having an end portion on which the bearing housing is installed fixedly, and having an opposite end portion pivotably supported by the base portion; and
- an adjusting device for pivoting the arm to move the pair of drums toward or away from each other.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a continuous casting apparatus and a continuous casting method, which are designed to lessen the influence of hysteresis due to frictional resistance when drums are moved toward or away from each other.
2. Description of the Related Art
A continuous casting apparatus of a twin drum type (or twin drum type continuous casting apparatus) accumulates a molten metal between a pair of drums, and produces a sheet (cast piece) continuously while rotating the drums.
The basic configuration of the twin drum type continuous casting apparatus will be described by reference to FIG. 15. As shown in FIG. 15, a pair of drums 1 a and 1 b are disposed in proximity, with their axes of rotation being parallel to each other, and are supported to be rotatable in opposite directions. The opposite ends in the axial direction of both drums 1 a and 1 b are stopped by side checks 2 a and 2 b. A molten metal 4 is poured into a pouring basin 3 surrounded by the drums 1 a, 1 b and the side checks 2 a, 2 b and formed thereby.
When the drums 1 a and 1 b are rotated in the opposite directions (when they are rotated so as to pull in the molten metal 4 downward), the molten metal 4 is cooled upon contact with the drums 1 a, 1 b. As a result, a solidified shell is formed. The solidified shells on both drums grow as the drums are rotated. These shells are pressure-bonded and integrated in a minimum gap area 5 of the drums 1 a, 1 b, and withdrawn as a cast piece 6.
In the above-described twin drum type continuous casting apparatus, an adjusting device for moving the drums 1 a and 1 b toward and away from each other may be provided for adjusting the clearance and pressure bonding load between the drums 1 a and 1 b.
The twin drum type continuous casting apparatus, equipped with the adjusting device for moving the drums 1 a and 1 b toward and away from each other, will be described by reference to FIG. 16 as a plan view, and FIG. 17 as a sectional view taken on line X-X in FIG. 16. In FIG. 16, the apparatus is illustrated, with an upper frame 12 being detached.
As shown in FIGS. 16 and 17, a molten metal 4 is poured into a pouring basin 3 surrounded by drums 1 a, 1 b and side checks 2 a, 2 b and formed thereby. When the drums 1 a and 1 b are rotated in the opposite directions, a cast piece 6 is taken out of a minimum gap area 5.
Frames 10, 10 are disposed in proximity to opposite end surfaces in the axial direction of the drums 1 a and 1 b placed adjacently. Bach frame 10 is composed of a lower frame 11 and an upper frame 12 to be a frame-shaped structure. When the drum 1 a or 1 b is to be replaced, the upper frame 12 can be detached from the lower frame 11.
A drum shaft 20 protrudes from each of the opposite end surfaces of the drum 1 a. Each drum shaft 20 is rotatably supported by a main bearing housing 21. Thus, the drum 1 a can be rotated about its axis.
The main bearing housing 21 is located between the lower frame 11 and the upper frame 12. Moreover, a linear bearing 22 a is provided between a lower part of the main bearing housing 21 and the lower frame 11, while a linear bearing 22 b is provided between an upper part of the main bearing housing 21 and the upper frame 12.
Thus, the drum 1 a and the main bearing housing 21 rotatably supporting the drum 1 a can slide along the linear bearings 22 a, 22 b. As a result, the drum 1 a can approach and separate from the drum 1 b.
A screw-down cylinder 23 as an adjusting device is interposed between the lower frame 11 and the main bearing housing 21. Upon expansion or contraction of the screw-down cylinder 23 (its expansion or contraction in the direction of a double-headed arrow A in FIG. 16), the main bearing housing 21 moves slidingly.
A drum shaft 30 protrudes from each of the opposite end surfaces of the drum 1 b. Each drum shaft 30 is rotatably supported by a main bearing housing 31. Thus, the drum 1 b can be rotated about its axis.
The main bearing housing 31 is located between the lower frame 11 and the upper frame 12. Moreover, a linear bearing 32 a is provided between a lower part of the main bearing housing 31 and the lower frame 11, while a linear bearing 32 b is provided between an upper part of the main bearing housing 31 and the upper frame 12.
Thus, the drum 1 b and the main bearing housing 31 rotatably supporting the drum 1 b can slide along the linear bearings 32 a, 32 b.
A load detector 33 is interposed between the lower frame 11 and the main bearing housing 31. The load detector 33 detects the load (screw-down force) between the drums 1 a and 1 b.
The amount of expansion or contraction of the screw-down cylinder 23 is adjusted such that the load detected by the load detector 33 becomes a preset target load.
In the example illustrated in FIGS. 16 and 17, moreover, a preload mechanism is provided for preventing the adverse influence of backlash in the main bearing housing 21 or 31.
That is, a preload bearing housing 40 is mounted on the drum shaft 20 of the drum 1 a. The preload bearing housing 40 is pulled by a pull-back cylinder 41 in a direction in which it is separated from the drum 1 b (i.e., an α-direction in FIG. 16). In this manner, the drum shaft 20 is pulled by the pull-back cylinder 41 in the α-direction, whereby rolling elements within the main bearing housing 21 are pressed in one direction against apart of the inner surface of the bearing housing, with the result that run-outs of the shaft center ascribed to a radial clearance are decreased. Thus, the adverse influence of backlash in the main bearing housing 21 can be prevented.
Similarly, a preload bearing housing 42 is mounted on the drum shaft 30 of the drum 1 b. The preload bearing housing 42 is pulled by a pull-back cylinder 43 in a direction in which it is separated from the drum 1 a (i.e., a β-direction in FIG. 16). In this manner, the drum shaft 30 is pulled by the pull-back cylinder 43 in the β-direction, whereby rolling elements within the main bearing housing 31 are pressed in one direction against a part of the inner surface of the bearing housing, with the result that run-outs of the shaft center ascribed to a radial clearance are decreased. Thus, the adverse influence of backlash in the main bearing housing 31 can be prevented.
In the example shown in FIGS. 16 and 17, the frictional resistances of the linear bearings 22 a, 22 b, 32 a, 32 b are lower than the frictional resistance of a slide guide which is lubricated with a lubricating oil or the like. This lessens hysteresis due to the frictional resistance generated when the main bearing housings 21, 31 are moved (slid) along the linear bearings 22 a, 22 b, 32 a, 32 b.
Since the hysteresis due to the frictional resistance is lessened, the position control of the main bearing housing 21 can be exercised relatively easily according to pushing force or pulling force generated by the screw-down cylinder 23. Consequently, control over the screw-down force can be performed easily and accurately in comparison with the use of a slide guide lubricated with a lubricating oil or the like.
FIG. 18 schematically shows the relationship among forces generated when the main bearing housing 21 is slid in the example illustrated in FIGS. 16 and 17.
Let the force generated by the screw-down cylinder 23 for moving the main bearing housing 21 in opposition to friction be F₂, the coefficient of friction caused to the linear bearing 22 a during the slide of the main bearing housing 21 be μ₂, the frictional force caused to the linear bearing 22 a during the slide of the main bearing housing 21 be f₂, and the weight of the drum 1 a be W₂. Then, the following equations (1) and (2) hold:
f ₂=±μ₂ ·W ₂ (1)
F ₂ =f ₂=±μ₂ ·W ₂ (2)
In the earlier technology shown in FIGS. 16 and 17, the linear bearings 22 a, 22 b, 32 a, 32 b with low frictional resistance are used. Thus, the decrease in the hysteresis due to the frictional resistance has been achieved successfully.
Because of the great frictional force f₂represented by the above formula (1), however, the force F₂represented by the equation (2) also changes. In this case, it becomes difficult to exercise control of the screw-down force. That is, if the frictional force f₂occurs, the force that the screw-down cylinder 23 has to generate in pushing the main bearing housing 21 by a certain distance so that the drum 1 a approaches the drum 1 b differs from the force that the screw-down cylinder 23 has to generate in pulling back the main bearing housing 21 by a certain distance so that the drum 1 a separates from the drum 1 b. This makes control of the screw-down force difficult.
Concretely, the parallelism between the upper, lower, right and left linear bearings 22 a, 22 a, 22 b, 22 b, i.e., the total four linear bearings, which slidingly move the main bearing housings 21 on the drive side, may be disturbed by an error in mounting or the like. Alternatively, the parallelism between the upper, lower, right and left linear bearings 32 a, 32 a, 32 b, 32 b, i.e., the total four linear bearings, which slidingly move the main bearing housings 31 on the driven side, may be disturbed by an error in mounting or the like. In this case, great hysteresis occurs owing to the frictional force, when the main bearing housing 21 or 31 is slid.
If such a high hysteresis occurs, the moving distance of the main bearing housing 21 when the screw-down cylinder 23 generates a certain push-out force in bringing the main bearing housings 21 and 31 ( drums 1 a and 1 b) close to each other differs from the moving distance of the main bearing housing 21 when the screw-down cylinder 23 generates a certain pull-back force in separating the main bearing housings 21 and 31 ( drums 1 a and 1 b) from each other. This adversely affects the control of the screw-down force.
Even when the linear bearings 22 a, 22 b, 32 a, 32 b are mounted without disturbance of their parallelism, the parallelism of the linear bearings 22 a, 22 b, 32 a, 32 b is disturbed, and hysteresis increases, if the frame 10 thermally deforms.
The present invention has been accomplished in light of the above-described problems with the earlier technology. It is an object of the invention to provide a continuous casting apparatus and a continuous casting method which can decrease frictional force as a factor of hysteresis during movement of a main bearing housing and, even if frictional force occurs, can reduce the influence of the frictional force-associated hysteresis on an adjusting device for moving the main bearing housing.

SUMMARY OF THE INVENTION

A first aspect of the present invention is a continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,
the continuous casting apparatus comprising, on a side of at least one of the drums:
a base portion;
an arm having an end portion on which the bearing housing is installed fixedly, and having an opposite end portion pivotably supported by the base portion; and
an adjusting device for pivoting the arm to move the pair of drums toward or away from each other.
A second aspect of the present invention is the above continuous casting apparatus further comprising a ring-shaped rolling bearing disposed in a part of the base portion where the arm is pivotably supported by the base portion.
A third aspect of the present invention is the above continuous casting apparatus characterized in that the arm is provided with a jutting portion which extends from a center of the part of the base portion, where the arm is pivotably supported by the base portion, in a direction opposite to the bearing housing installed on the one end portion of the arm, and the adjusting device pivots the jutting portion to move the pair of drums toward or away from each other.
In the continuous casting apparatus, the adjusting device may be an expanding and contracting device which pushes or pulls the arm to pivot the arm.
In the continuous casting apparatus, the adjusting device may be a device which generates a rotating force for rotating a rotating shaft of the arm rotatably supported by the base portion.
The continuous casting apparatus may further comprise pushing force detecting means for detecting a force generated by the adjusting device, or may further comprise a control section for controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.
The continuous casting apparatus may further comprise distance detecting means for detecting a distance between the drums which have been moved toward or away from each other by the adjusting device, or may further comprise a control section for controlling an operation of the adjusting device such that the distance detected by the distance detecting means becomes a distance within a predetermined range.
The continuous casting apparatus may further comprise rotating force detecting means for detecting the force generated by the adjusting device.
A fourth aspect of the present invention is a continuous casting method for a continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,
the continuous casting apparatus including, on a side of at least one of the drums,
a base portion,
an arm having an end portion on which the bearing housing is installed fixedly, and being pivotably supported by the base portion,
an adjusting device for pivoting the arm to move the pair of drums toward or away from each other, and
pushing force detecting means for detecting a force generated by the adjusting device,
the continuous casting method comprising:
controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.
A fifth aspect of the present invention is a continuous casting method for a continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,
the continuous casting apparatus including, on a side of at least one of the drums,
a base portion,
an arm having an end portion on which the bearing housing is installed fixedly, and being pivotably supported by the base portion,
an adjusting device for pivoting the arm to move the pair of drums toward or away from each other, and
distance detecting means for detecting a distance between the drums moved toward or away from each other by the adjusting device,
the continuous casting method comprising:
controlling an operation of the adjusting device such that a distance detected by the distance detecting means becomes a distance within a predetermined range.
As described above, the present invention adopts the hinge structure in which the bearing housing rotatably supporting the drum is fixedly installed at one end part (upper part) of the arm, and the arm is pivotably supported by the base portion. Thus, even if hysteresis due to frictional force occurs in the part of the base portion where the arm is pivotably supported by the base portion, the influence of the frictional force on the adjusting device, which pivots the arm and the bearing housing, can be reduced.
This is because the length of the arm is so large that the torque acting on the rotatably supporting portion by pushing the drum is greater than the frictional torque generated by the slide at the rotatably supporting portion.
Another reason is that the rotatably supporting portion is located at the position spaced from the drum, and minimally undergoes the thermal influence of the molten metal, and thus resists thermal deformation.
Hence, even if hysteresis due to frictional force occurs in the part of the base portion where the arm is pivotably supported by the base portion, the influence of the hysteresis is minimally exerted, and the screw-down force can be controlled with high accuracy.
Furthermore, the ring-shaped rolling bearing is provided in the part of the base portion where the arm is pivotably supported by the base portion. By so doing, friction itself can be decreased, and a further increase in the accuracy of control over the screw-down force can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a plan view showing a continuous casting apparatus according to Embodiment 1 of the present invention;

FIG. 2 is a front view showing the continuous casting apparatus according to Embodiment 1;

FIG. 3 is an explanation drawing schematically showing the relationship among forces generated when an arm is pivoted in the continuous casting apparatus according to Embodiment 1;

FIG. 4 is a front view showing a continuous casting apparatus according to Embodiment 2 of the present invention;

FIG. 5 is a front view showing a continuous casting apparatus according to Embodiment 3 of the present invention;

FIG. 6 is a front view showing a continuous casting apparatus according to Embodiment 4 of the present invention;

FIG. 7 is a front view showing a continuous casting apparatus according to Embodiment 5 of the present invention;

FIG. 8 is a front view showing a continuous casting apparatus according to Embodiment 6 of the present invention;

FIG. 9 is a front view showing a continuous casting apparatus according to Embodiment 7 of the present invention;

FIG. 10 is a configurational drawing showing a continuous casting apparatus according to Embodiment 8 of the present invention;

FIG. 11 is a flow chart showing the operating state of the continuous casting apparatus according to Embodiment 8;

FIG. 12 is a configurational drawing showing a continuous casting apparatus according to Embodiment 9 of the present invention;

FIG. 13 is a flow chart showing the operating state of the continuous casting apparatus according to Embodiment 9;

FIG. 14 is a plan view showing a drum portion of a continuous casting apparatus according to Embodiment 10 of the present invention;

FIG. 15 is a configurational drawing showing the basic configuration of a twin drum type continuous casting apparatus;

FIG. 16 is a plan view showing a conventional twin drum type continuous casting apparatus equipped with an adjusting device;

FIG. 17 is a sectional view taken on line X-X in FIG. 16; and

FIG. 18 is an explanation drawing schematically showing the relationship among forces when a main bearing housing is slid in the conventional twin drum type continuous casting apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The best mode for carrying out the present invention will be described in detail based on the following embodiments with reference to the accompanying drawings.

Embodiment 1

A twin drum type continuous casting apparatus according to Embodiment 1 of the present invention will be described by reference to FIG. 1 as a plan view and FIG. 2 as a front view.
As shown in FIGS. 1 and 2, a pair of drums 101 a and 101 b are disposed in proximity, with their axes of rotation being parallel to each other and horizontal, and are supported to be rotatable in opposite directions. Details of supporting structures for the drums will be described later. The opposite ends in the axial direction of both drums 101 a and 101 b are stopped by side checks 102 a, 102 b. A molten metal 104 is poured into a pouring basin 103 surrounded by the drums 101 a, 101 b and the side checks 102 a, 102 b and formed thereby.
When the drums 101 a, 101 b are rotated in the opposite directions (when they are rotated so as to pull in the molten metal 104 downward), the molten metal 104 is cooled upon contact with the drums 101 a, 101 b. As a result, a solidified shell is formed on each of the surfaces of the drums 101 a and 101 b. Both solidified shells grow as the drums are rotated. These shells are pressure-bonded and integrated in a minimum gap area 105 of the drums 101 a, 101 b, and withdrawn as a cast piece 106.
A drum shaft 120 protrudes from each of the opposite end surfaces of the drum 101 a. Each drum shaft 120 is provided with a main bearing housing 121, and the drum shaft 120 is rotatably supported by the main bearing housing 121.
The main bearing housing 121 rotatably supporting the drum shaft 120 is fixedly installed at an upper part (an end part) of an arm 150.
The arm 150 has a lower part (an opposite end part) thereof fixed to a rotating shaft 151, and the rotating shaft 151 is rotatably supported by a base portion 152 via a ring-shaped bearing (a rolling bearing). Since such a hinge structure is adopted, the arm 150 (and the main bearing housing 121 attached to the arm 150, and the drum 101 a) can pivot with respect to the base portion 152, with the shaft center of the rotating shaft 151 as the center of rotation.
A screw-down cylinder 123 as an adjusting device is connected to the main bearing housing 121 via a load detector 133. Upon expansion or contraction of the screw-down cylinder 123, the arm 150 pivots (swings) to move the drum 101 a toward or away from the drum 101 b. That is, an expansion or contraction force generated by the screw-down cylinder 123 acts on the main bearing housing 121 to pivot (swing) the arm 150, thereby bringing the drum 101 a close to or away from the drum 101 b.
A drum shaft 130 protrudes from each of the opposite end surfaces of the drum 101 b. Each drum shaft 130 is rotatably supported by a main bearing housing 131. The main bearing housing 131 is fixedly installed at a frame (not shown). Thus, the drum 101 b can be rotated about its axis, but the position of disposition of the entire drum 101 b does not move.
Here, the screw-down cylinder 123 is adopted as an adjusting device, but the adjusting device can be constituted not only by the cylinder, but also by a motor or the like which generates a rotating force and pivots the arm by this rotating force. That is, the adjusting device is not limited to the cylinder, as long as it can apply a swinging force to the drum shaft 120 via the main bearing housing 121 to pivot (swing) the arm 150.
The load detector (a pushing force detecting means) 133 detects the load (screw-down force) between the drums 101 a and 101 b. A load cell, a pressure gauge, or a torque meter, for example, can be used as the load detector 133.
The amount of expansion or contraction of the screw-down cylinder 123, or the amount of rotation of the motor is adjusted such that the load detected by the load detector 133 becomes a preset target load.
In the present embodiment, moreover, a preload mechanism is provided for preventing the adverse influence of backlash in the main bearing housing 121.
That is, a preload bearing housing 140 is mounted on the drum shaft 120 of the drum 101 a. The preload bearing housing 140 is pulled by a preload applicator 141 in a direction in which it is separated from the drum 101 b (i.e., a γ-direction in FIG. 1). In this manner, the drum shaft 120 is pulled by the preload applicator 141 in the γ-direction, whereby rolling elements within the main bearing housing 121 are pressed in one direction against a part of the inner surface of the bearing housing, with the result that run-outs of the shaft center ascribed to a radial clearance are decreased. Thus, the adverse influence of backlash in the main bearing housing 121 can be prevented.
Also, a preload applicator may be mounted on the drum shaft 130 of the drum 101 b.
As the preload applicator 141, a cylinder, a spring, a weight or the like can be used. Moreover, a preload may be imposed by the preload applicator such that the distance between the drum shaft 120 and the drum shaft 130 is increased.
With the continuous casting apparatus of such a configuration, when the screw-down cylinder 123 expands, the arm 150 pivots (pivots clockwise in FIG. 2), with the shaft center of the rotating shaft 151 as the center of rotation, whereupon the drum 101 a approaches the drum 101 b. Thus, the load (screw-down force) between the drums 101 a and 101 b increases.
When the screw-down cylinder 123 contracts, on the other hand, the arm 150 pivots (pivots counterclockwise in FIG. 2), with the shaft center of the rotating shaft 151 as the center of rotation, whereupon the drum 101 a separates from the drum 101 b. Thus, the load (screw-down force) between the drums 101 a and 101 b decreases.
The load between the drums 101 a and 101 b is detected by the load detector 133, and the amount of expansion or contraction of the screw-down cylinder 123 is adjusted such that the detected load becomes the target load.
FIG. 3 schematically shows the relationship among forces when the arm 150, accordingly, the main bearing housing 121 and the drum 101 a, are pivoted in the continuous casting apparatus illustrated in FIGS. 1 and 2.
Let the force generated by the screw-down cylinder 123 for pivoting the arm 150 in opposition to friction at the bearing provided between the rotating shaft 151 and the base portion 152 be F₁, the coefficient of friction caused to the bearing when the arm 150 is pivoted be μ₁, the frictional force caused to the bearing when the arm 150 is pivoted be f₁, the weight of the drum 101 a be W₁, the radius of the rotating shaft 151 be r₁, and the distance between the shaft center of the rotating shaft 151 and the shaft center of the drum shaft 120 (the shaft center of the drum 101 a) be R₁. Then, the following equations (3), (4) and (5) hold:
f ₁=±μ₁ ·W ₁ (3)
F ₁ ·R ₁ =f ₁ ·r ₁=±μ₁ ·W ₁ ·r ₁ (4)
F ₁=(±μ₁ ·W ₁ ·r ₁)/R ₁ (5)
The length of the arm 150 is larger than the radius r₁of the rotating shaft 151. That is, the relationship R₁>r₁holds. As seen from the equation (5), therefore, even if the force F₁generated by the screw-down cylinder 123 is low, the arm 150 (and the main bearing housing 121 and the drum 101 a) can be pivoted easily.
In other words, even if the force generated by the screw-down cylinder 123 is low, great torque can be applied to the rotating shaft 151, because the length of the arm 150 is large. Consequently, the arm 150 (and the main bearing housing 121 and the drum 101 a) can be pivoted with ease.
Because of an error in mounting or the like, hysteresis may result from the frictional force produced in the bearing provided between the rotating shaft 151 and the base portion 152. As a result, a situation may arise in which the force needed to pivot the arm 150 clockwise is different from the force needed to pivot the arm 150 counterclockwise. Even in such a situation, the influence that the hysteresis due to the frictional force has on the screw-down cylinder 123 diminishes thanks to the above-mentioned advantage.
In addition, the configuration in which the rotating shaft 151 is disposed rotatably in the base portion 152 via the ring-shaped bearing is less apt to cause hysteresis than a configuration in which a plurality of linear bearings are arranged in parallel. This is because the mechanical construction accuracy of the hinge structure in which the rotating shaft 151 is rotatably provided in the base portion 152 via the ring-shaped bearing is generally higher than the mechanical construction accuracy of the configuration in which the plurality of linear bearings are precisely positioned and mounted with ensured parallelism.
Thus, even if a frictional force occurs in the bearing provided between the rotating shaft 151 and the base portion 152 owing to the error in mounting or the like, hysteresis due to the frictional force is almost absent when the screw-down cylinder 123 is expanded or contracted.
As a result, in the event of hysteresis due to the frictional force, the clockwise moving distance and the counterclockwise moving distance of the arm 150 nearly equal even when the push-out force which the screw-down cylinder 123 generates for pivoting the arm 150 so as to move the drum 101 a toward the drum 101 b is set to equal the pull-back force which the screw-down cylinder 123 generates for pivoting the arm 150 so as to move the drum 101 a away from the drum 101 b. Hence, the control of the screw-down force can be exercised with accuracy and ease.
Furthermore, the rotating shaft 151 is located at a position spaced from the high temperature molten metal 104. Thus, the rotating shaft 151 undergoes minimal thermal deformation, and the occurrence of hysteresis ascribed to thermal deformation can be suppressed.

Embodiment 2

Next, a twin drum type continuous casting apparatus according to Embodiment 2 of the present invention will be described by reference to FIG. 4. Portions which perform the same functions as those in Embodiment 1 shown in FIGS. 1 and 2 will be assigned the same numerals as in Embodiment 1, and an explanation for duplicate portions will be simplified.
In Embodiment 2, in connection with the surroundings of a drum 101 a, an arm 150 (and a main bearing housing 121 attached to the arm 150, and the drum 101 a) can pivot with respect to a base portion 152, with the shaft center of a rotating shaft 151 as the center of rotation, as in Embodiment 1. A load detector 133 is installed on the side of a drum 101 b.
The structure surrounding the drum 101 b cannot move in the horizontal direction in Embodiment 1, but can move slidingly in the horizontal direction in Embodiment 2.
The structure surrounding the drum 101 b will be described here.
A drum shaft 130 protrudes from each of the opposite end surfaces of the drum 101 b. Each drum shaft 130 is rotatably supported by a main bearing housing 131. Thus, the drum 101 b can be rotated about its axis.
The main bearing housing 131 is located between a lower frame 111 and an upper frame 112 of a frame 110. Moreover, a linear bearing 132 a is provided between a lower part of the main bearing housing 131 and the lower frame 111, while a linear bearing 132 b is provided between an upper part of the main bearing housing 131 and the upper frame 112.
Thus, the drum 101 b and the main bearing housing 131 rotatably supporting the drum 101 b can slide along the linear bearings 132 a, 132 b.
The load detector 133 is interposed between the lower frame 111 and the main bearing housing 131. The load detector 133 detects the load (screw-down force) between the drums 101 a and 101 b.
The amount of expansion or contraction of a screw-down cylinder 123 is adjusted such that the load detected by the load detector 133 becomes a preset target load.
Embodiment 2 also adopts a hinge structure in which the arm 150 (and the main bearing housing 121 attached to the arm 150, and the drum 101 a) can pivot with respect to the base portion 152, with the shaft center of the rotating shaft 151 as the center of rotation. Thus, even if hysteresis occurs owing to a frictional force generated in the bearing provided between the rotating shaft 151 and the base portion 152 because of an error in mounting or the like, the influence of the hysteresis is almost absent when the screw-down cylinder 123 is expanded or contracted.
Hence, the control of the screw-down force can be exercised with accuracy and ease.

Embodiment 3

Next, a twin drum type continuous casting apparatus according to Embodiment 3 of the present invention will be described by reference to FIG. 5.
In Embodiment 3, the diameter of a drum 101 b is great as compared with the diameter of a drum 101 a. That is, the apparatus illustrated here is a continuous casting apparatus involving the drums of different diameters.
The features and actions of other portions are the same as those in Embodiment 1.

Embodiment 4

Next, a twin drum type continuous casting apparatus according to Embodiment 4 of the present invention will be described by reference to FIG. 6.
In Embodiment 4, an arm 150 is lengthened, and a rotating shaft 151 is fixed to a nearly central position of the arm 150. The rotating shaft 151 is rotatably supported by a base portion 152 via a ring-shaped bearing.
A main bearing housing 121 is fixedly installed at an upper part (an end part) of the arm 150. A screw-down cylinder 123 is connected to a lower part of the arm 150 (“a jutting portion” extending on a side opposite to the main bearing housing 121 across the rotating shaft 151). In this example, a load detector 133 is interposed between the screw-down cylinder 123 and the lower part of the arm 150.
In Embodiment 1, the screw-down cylinder 123 is disposed adjacently to the drum 101 a. In Embodiment 4, on the other hand, the screw-down cylinder 123 can be disposed at a position spaced from the drum 101 a (i.e., a position adjacent to the lower part of the arm 150). That is, the screw-down cylinder 123 can be disposed on a side opposite to the drum 101 a across the rotating shaft 151.
As seen above, the screw-down cylinder 123 can be disposed at the position spaced from the drum 101 a. Thus, a space can be provided adjacently to the drum 101 a, and the degree of freedom can be obtained for a design surrounding the drum.
If the distance L1 is lengthened as compared with the distance L2 in the configuration shown in FIG. 6, an acting force generated at the main bearing housing 121 becomes high in comparison with an acting force generated by the screw-down cylinder 123. Thus, the screw-down cylinder 123 as an adjusting device can be decreased in size. That is, the acting force of the screw-down cylinder 123 as the adjusting device can be increased.
If the distance L1 is shortened as compared with the distance L2 in the configuration shown in FIG. 6, on the other hand, the operating distance at the main bearing housing 121 becomes long compared with the operating distance at the screw-down cylinder 123. That is, the operating speed at the main bearing housing 121 can be increased in comparison with the operating speed of the screw-down cylinder 123 as the adjusting device.
The distance L2 is the distance from the center (shaft center) of the rotating shaft 151, which is the portion for supporting the arm 150 to be rotatable with respect to the base portion 152, to the main bearing housing 121 installed at the one end part of the arm 150.
The distance L1 is the distance from the center (shaft center) of the rotating shaft 151, which is the portion for supporting the arm 150 rotatably on the base portion 152, to the point of action on which the force of the screw-down cylinder 123 as the adjusting device acts.

Embodiment 5

Next, a twin drum type continuous casting apparatus according to Embodiment 5 of the present invention will be described by reference to FIG. 7. Embodiment 5 is a modification of Embodiment 1.
In Embodiment 5, the leading end of a sub-arm 153 is fixed to a rotating shaft 151, and a screw-down cylinder 123 is connected to the proximal end of the sub-arm 153.
Thus, upon expansion or contraction of the screw-down cylinder 123, the sub-arm 153 pivots to turn the rotating shaft 151. The turning of the rotating shaft 151 pivots (swings) an arm 150, whereby a drum 101 a moves toward or away from a drum 101 b.
The features and actions of other portions are the same as those in Embodiment 1.

Embodiment 6

Next, a twin drum type continuous casting apparatus according to Embodiment 6 of the present invention will be described by reference to FIG. 8. Portions which perform the same functions as those in Embodiment 1 shown in FIGS. 1 and 2 will be assigned the same numerals as in Embodiment 1, and an explanation for duplicate portions will be simplified.
In Embodiment 6, not only a main bearing housing 121 beside a drum 101 a, but also a main bearing housing 131 beside a drum 101 b can pivot (swing).
That is, in connection with the surroundings of the drum 101 a, an arm 150 (and the main bearing housing 121 attached to the arm 150, and the drum 101 a) can pivot with respect to a base portion 152, with the shaft center of a rotating shaft 151 as the center of rotation, as in Embodiment 1. A load detector 133 is installed on the side of the drum 101 a.
The structure surrounding the drum 101 b is of the same configuration as that of the structure surrounding the drum 101 a.
That is, the main bearing housing 131 rotatably supporting a drum shaft 130 of the drum 101 b is fixedly installed at an upper part of an arm 150A.
The arm 150A has a lower part thereof fixed to a rotating shaft 151A, and the rotating shaft 151A is rotatably supported by a base portion 152A via a ring-shaped bearing. Since such a hinge structure is adopted, the arm 150A (and the main bearing housing 131 attached to the arm 150A, and the drum 101 b) can pivot with respect to the base portion 152A, with the shaft center of the rotating shaft 151A as the center of rotation.
A screw-down cylinder 123A as an adjusting device is connected to the main bearing housing 131. Upon expansion or contraction of the screw-down cylinder 123A, the arm 150A pivots (swings) to move the drum 101 b toward or away from the drum 101 a.
That is, in Embodiment 6, the expansion and contraction of the screw-down cylinder 123 and the screw-down cylinder 123A adjust the screw-down force between the drums 101 a and 101 b.

Embodiment 7

Next, a twin drum type continuous casting apparatus according to Embodiment 7 of the present invention will be described by reference to FIG. 9. Portions which perform the same functions as those in Embodiment 1 shown in FIGS. 1 and 2 will be assigned the same numerals as in Embodiment 1, and an explanation for duplicate portions will be simplified.
In Embodiment 7, a servomotor 200 for generating a rotating force is adopted as an adjusting device, and a torque meter 201 for detecting a rotating force is adopted as a load detecting means which detects a pressure bonding load.
When the servomotor 200 turns, its turning force is transmitted to a rotating shaft 151 via the torque meter 201 to turn the rotating shaft 151. In accordance with the turning of the rotating shaft 151, an arm 150 pivots (swings), whereupon a drum 101 a approaches or separates from a drum 101 b.
The pressure bonding load (screw-down force) between the drums 101 a and 101 b is detected by the torque meter 201, and the amount of turning of the servomotor 200 is adjusted such that the load detected by the torque meter 201 becomes a target load.
An encoder 200 a is installed in the servomotor 200 to detect a rotational angle. Using the rotational angle detected by the encoder 200 a and the distance from the rotating shaft 151 to a drum shaft 120, the distance between the drums is calculated by a well-known method.

Embodiment 8

Next, a twin drum type continuous casting apparatus according to Embodiment 8 of the present invention will be described by reference to FIG. 10 as a configurational drawing and FIG. 11 as a motion flow chart. Portions which perform the same functions as those in Embodiment 1 shown in FIGS. 1 and 2 will be assigned the same numerals as in Embodiment 1, and an explanation for duplicate portions will be simplified.
As shown in FIG. 10, a control section 300 is provided in Embodiment 8. A pushing force (load) f detected by a load detector (pushing force detecting means) 133 is sent to the control section 300.
The control section 300 sets a new position operating command S for a screw-down cylinder 123, which is conformed to the difference between a target pushing force and the detected pushing force f, so that the detected pushing force f will become a force within a preset range.
The set operating command S is sent to a servo valve or the like (not shown) to control the position of the screw-down cylinder 123. As a result, a force generated by the screw-down cylinder 123 is adjusted.
The operating state for control in Embodiment 8 will be described based on FIG. 11.
First of all, the pushing force f is detected by the load detector 133 (Step 1).
The control section 300 compares a set value, which has bee preset, with the detected pushing force f to find the difference between the set value and the pushing force f (Step 2).
The control section 300 determines whether the difference between the set value and the pushing force f is within a predetermined range (Step 3).
If the difference between the set value and the pushing force f is not within the predetermined range, the control section 300 changes the value of the operating command S to control the difference between the set value and the pushing force f to within the predetermined range (Step 4).
When the difference between the set value and the pushing force f is within the predetermined range, the control section 300 maintains the current value of the operating command S.
In Embodiment 8, the pushing force comes to a force within the predetermined range. Thus, a solidified shell formed on the surface of the drum 101 a, and a solidified shell formed on the surface of the drum 101 b are pressure-bonded and integrated, under optimal load, in a minimum gap area. Hence, a satisfactory cast piece 106 can be produced.

Embodiment 9

Next, a twin drum type continuous casting apparatus according to Embodiment 9 of the present invention will be described by reference to FIG. 12 as a configurational drawing and FIG. 13 as a motion flow chart. Portions which perform the same functions as those in Embodiment 1 shown in FIGS. 1 and 2 will be assigned the same numerals as in Embodiment 1, and an explanation for duplicate portions will be omitted.
As shown in FIG. 12, a control section 350 is provided in Embodiment 9. A screw-down cylinder 123 is provided with a distance detector 351. The distance detector 351 directly detects the amount of expansion or contraction of the screw-down cylinder 123, and this amount of expansion or contraction is proportional to the distance between drums 101 a and 101 b. Thus, the distance detector 351 detects the amount of expansion or contraction of the screw-down cylinder 123 to output a detected distance k representing the distance between the drums 101 a and 101 b.
The detected distance k detected by the distance detector 351 is sent to the control section 350.
The control section 350 sets a new position operating command S for the screw-down cylinder 123, which is conformed to the difference between a target distance and the detected distance k, so that the detected distance k will become the preset target distance.
The set operating command S is sent to a servo valve or the like (not shown) to control the position of the screw-down cylinder 123. As a result, the distance between the drums 101 a and 101 b is adjusted.
The operating state for control in Embodiment 9 will be described based on FIG. 13.
First of all, the detected distance k is detected by the distance detector 351 (Step 11).
The control section 350 compares a set value, which has bee preset, with the detected distance k to find the difference between the set value and the detected distance k (Step 12).
The control section 350 determines whether the difference between the set value and the detected distance k is within a predetermined range (Step 13).
If the difference between the set value and the detected distance k is not within the predetermined range, the control section 350 changes the value of the operating command S to control the difference between the set value and the detected distance k to within the predetermined range (Step 14).
When the difference between the set value and the detected distance k is within the predetermined range, the control section 350 maintains the current value of the operating command S.
In Embodiment 9, the distance between the drums 101 a and 101 b comes to a distance within the predetermined range. Thus, the thickness of a cast piece 106 can be optimally controlled to a set thickness.

Embodiment 10

In each of the above Embodiments, the drum of a cylindrical shape is used. However, the present invention can be applied to a continuous casting apparatus using a pair of drums 301 and 302 of a so-called concave type as shown in FIG. 14.
With a continuous casting apparatus of the type shown in FIG. 14, when the pair of concave drums 301 and 302 are rotated in opposite directions, a molten steel 303 contacts the surfaces of the drums 301 and 302. As a result, the molten steel 303 is cooled to form solidified shells 304, 305. Opposite end portions of the solidified shell 304 and the solidified shell 305 are pressure-bonded and integrated in a minimum gap area between the drums 301 and 302. Thus, the solidified shells 304 and 305 are joined together to form a cast piece, with the molten steel 303 remaining in a central part of these shells.
The cast piece withdrawn from the drums 301 and 302 has the unsolidified molten steel 303 left in its center, but this molten steel 303 is cooled and solidified during transport.
With the continuous casting apparatus of the type shown in FIG. 14, only the opposite end portions of the solidified shell 304 and the solidified shell 305 are pressure-bonded and integrated. Thus, it is necessary to control the pressure bonding load with high accuracy.
If the present invention is adopted for the continuous casting apparatus in which the opposite end portions of the solidified shell 304 and the solidified shell 305 are pressure-bonded, with the molten steel 303 left in the central part of the solidified shells 304, 305, as shown in FIG. 14, the accuracy of the pressure bonding load can be improved, even in the presence of hysteresis due to frictional resistance. Thus, the opposite end portions of the solidified shell 304 and the solidified shell 305 can be pressure-bonded reliably and accurately.
It goes without saying that the present invention can be applied even to a continuous casting apparatus in which one of the drums is a concave drum and the other drum is a cylindrical drum.
The shape of the concave drum is not limited to the one shown in FIG. 14. This drum is available in various shapes in which the diameters of both ends of the drum are larger than the diameter of the central part of the drum.
Furthermore, the present invention can be applied to a continuous casting apparatus of a type horizontal type) in which one of the drums is disposed on an upper side, while the other drum is disposed on a lower side, and the resulting cast piece is withdrawn in the horizontal direction.
The invention thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

the continuous casting apparatus comprising, on a side of at least one of the drums:

a base portion;

an arm having an end portion on which the bearing housing is installed fixedly, and having an opposite end portion pivotably supported by the base portion; and

an adjusting device for pivoting the arm to move the pair of drums toward or away from each other.

2. A continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

a base portion;

an arm having an end portion on which the bearing housing is installed fixedly, and having an opposite end portion pivotably supported by the base portion;

an adjusting device for pivoting the arm to move the pair of drums toward or away from each other; and

a ring-shaped rolling bearing disposed in a part of the base portion where the arm is pivotably supported by the base portion.

3. A continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

a base portion;

a ring-shaped rolling bearing disposed in a part of the base portion where the arm is pivotably supported by the base portion,

wherein the arm is provided with a jutting portion which extends from a center of the part of the base portion, where the arm is pivotably supported by the base portion, in a direction opposite to the bearing housing installed on the one end portion of the arm, and

the adjusting device pivots the jutting portion to move the pair of drums toward or away from each other.

4. The continuous casting apparatus according to claim 1, wherein the adjusting device is an expanding and contracting device which pushes or pulls the arm to pivot the arm.

5. The continuous casting apparatus according to claim 4, further comprising pushing force detecting means for detecting a force generated by the adjusting device.

6. The continuous casting apparatus according to claim 5, further comprising a control section for controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.

7. The continuous casting apparatus according to claim 4, further comprising distance detecting means for detecting a distance between the drums which have been moved toward or away from each other by the adjusting device.

8. The continuous casting apparatus according to claim 7, further comprising a control section for controlling an operation of the adjusting device such that the distance detected by the distance detecting means becomes a distance within a predetermined range.

9. The continuous casting apparatus according to claim 1, wherein the adjusting device is a device which generates a rotating force for rotating a rotating shaft of the arm rotatably supported by the base portion.

10. The continuous casting apparatus according to claim 9, further comprising rotating force detecting means for detecting the force generated by the adjusting device.

11. A continuous casting method for a continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

the continuous casting apparatus including, on a side of at least one of the drums,

a base portion,

an arm having an end portion, on which the bearing housing is installed fixedly, and being pivotably supported by the base portion,

an adjusting device for pivoting the arm to move the pair of drums toward or away from each other, and

pushing force detecting means for detecting a force generated by the adjusting device,

the continuous casting method comprising:

controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.

12. A continuous casting method for a continuous casting apparatus having a pair of drums rotating in opposite directions, and bearing housings for rotatably supporting drum shafts protruding from opposite end surfaces of the drums,

a base portion,

distance detecting means for detecting a distance between the drums moved toward or away from each other by the adjusting device,

the continuous casting method comprising:

controlling an operation of the adjusting device such that a distance detected by the distance detecting means becomes a distance within a predetermined range.

13. The continuous casting apparatus according to claim 2, wherein the adjusting device is an expanding and contracting device which pushes or pulls the arm to pivot the arm.

14. The continuous casting apparatus according to claim 3, wherein the adjusting device is an expanding and contracting device which pushes or pulls the arm to pivot the arm.

15. The continuous casting apparatus according to claim 13, further comprising pushing force detecting means for detecting a force generated by the adjusting device.

16. The continuous casting apparatus according to claim 14, further comprising pushing force detecting means for detecting a force generated by the adjusting device.

17. The continuous casting apparatus according to claim 15, further comprising a control section for controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.

18. The continuous casting apparatus according to claim 16, further comprising a control section for controlling an operation of the adjusting device such that a pushing force detected by the pushing force detecting means becomes a force within a predetermined range.

19. The continuous casting apparatus according to claim 13, further comprising distance detecting means for detecting a distance between the drums which have been moved toward or away from each other by the adjusting device.

20. The continuous casting apparatus according to claim 14, further comprising distance detecting means for detecting a distance between the drums which have been moved toward or away from each other by the adjusting device.

21. The continuous casting apparatus according to claim 19, further comprising a control section for controlling an operation of the adjusting device such that the distance detected by the distance detecting means becomes a distance within a predetermined range.

22. The continuous casting apparatus according to claim 20, further comprising a control section for controlling an operation of the adjusting device such that the distance detected by the distance detecting means becomes a distance within a predetermined range.

23. The continuous casting apparatus according to claim 2, wherein the adjusting device is a device which generates a rotating force for rotating a rotating shaft of the arm rotatably supported by the base portion.

24. The continuous casting apparatus according to claim 3, wherein the adjusting device is a device which generates a rotating force for rotating a rotating shaft of the arm rotatably supported by the base portion.

25. The continuous casting apparatus according to claim 23, further comprising rotating force detecting means for detecting the force generated by the adjusting device.

26. The continuous casting apparatus according to claim 24, further comprising rotating force detecting means for detecting the force generated by the adjusting device.