JPH08226844A - Device and method for monitoring depth of molten-metal well of double-roll casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor the depth of molten sump constantly and accurately during casting work. SOLUTION: The molten sump depth monitor for twin roll casting machine has a gap 17 between a pair of casting rolls 12 and a molten sump 20 is disposed above the gap 17 while extending over the entire length of the gap 17. The molten sump depth monitor further comprises an optical inspection unit 23 supported contiguously to the casting rolls 12 while being spaced apart upward on the outside of one end of the molten sump 20 and aligned such that the field of view extends downward along the molten sump 20 so that the intersection of the surface of molten sump 20 and one casting surface of the casting roll 12 can be observed, and a display for presenting the movement of the intersection as the scale of variation in the depth of molten sump 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten pool depth monitoring apparatus and method for a twin roll casting machine for continuously casting metal strips.

[0002]

In twin roll casters, a molten metal is introduced between a pair of horizontal casting rolls that are cooled and rotated in opposite directions to solidify a metal shell on the surface of a moving casting roll, The metal shells are aligned in the roll gap and fed downward from the roll gap to produce a solidified metal strip product. As used herein, the term "roll gap" generally refers to the area where rolls are closest together. Molten metal is poured from a ladle into a small container, then poured through a metal supply nozzle located above the roll gap and directed toward the roll gap, forming a molten metal pool on the roll gap that extends in the length direction of the roll gap. Let By confining this molten metal pool with side closing plates or weir plates held so as to be slidably engaged with the roll ends, it is possible to prevent molten metal from flowing out from both ends of the molten metal pool.

[0003]

Particularly when casting ferrous metals on a twin roll caster, the depth of the molten metal pool must be strictly controlled during casting so as to deal with undesirable fluctuations in the molten metal pool depth. It is necessary to monitor and regulate the metal flow directed into the roll gap. Due to the extremely high temperature of the melt pool and the harsh environment, it is not possible to directly measure the depth of the melt pool using conventional sensing means, and some proximity detector in the space above the pool. Disposition is also impossible because the space is occupied by the metal feed nozzle. The present invention overcomes this problem and allows accurate monitoring of the depth of the molten metal pool during casting operations.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a molten pool depth monitor of a twin roll casting machine in which a roll gap is formed between a pair of casting rolls and a molten pool extending over the entire length of the roll gap is arranged on the roll gap. In the apparatus, it is supported adjacent to the casting roll so as to be spaced apart from one end of the molten metal pool and upwardly, and the field of view extends downward along the molten metal pool to form a surface of the molten metal pool and one of the casting roll casting surfaces. Twin roll casting characterized by comprising an optical inspection device which is aligned so as to provide a visual field for viewing the intersection, and a display device which displays the movement of the intersection as a measure of the depth change of the molten metal pool. Provide a molten metal pool depth monitoring device.

The optical inspection device may be composed of a video camera, and the display device may be composed of a signal processing device for processing a signal from the video camera and a screen for displaying an inspection image obtained from the signal. .

The present invention further provides a method for monitoring a depth of a molten metal pool in a twin roll casting machine, wherein a roll space is formed between a pair of casting rolls, and a molten metal pool extending over the entire length of the roll space is arranged on the roll space. During the casting operation at a position outward and upwardly spaced from one longitudinal end of the casting, and wherein the field of view extends downwards along the pool and includes a casting surface area above the roll gap in one of the casting rolls. The optical inspection device is supported before the casting operation so that the intersection of the molten pool surface and the casting roll casting surface can be seen in the casting surface area. Provided is a method for monitoring the depth of molten metal pool in a twin roll casting machine, which is characterized in that it is displayed as a scale of depth change.

The optical inspection device can be supported and aligned at said position before the casting operation and can be calibrated by looking at a series of positions on said roll surface area of known height above the roll gap. . The positioning can be established by placing measuring strips of different widths at different heights above the roll gap between the casting rolls and observing the intersection of these strips with the roll surface area.

By placing an optical inspection device outside the end of the casting roll in the lengthwise direction of the roll gap and aligning it along the roll gap, one side of the feed nozzle, very limited above the melt pool. However, it is possible to obtain a line of sight having a field of view which can monitor the essential movement of the boundary between the molten metal pool surface and the casting roll by taking in the casting roll surface area. Furthermore, thanks to this special field-of-view alignment, the melt pool depth due to roll curvature, such as that experienced when the line of sight is almost downward on the casting roll rather than mainly along the casting roll. The "crowding" effect of the movement corresponding to the even increment of is small.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In the illustrated twin roll casting machine, a main machine frame 11 rotatably supports a pair of parallel casting rolls 12. During the casting operation, molten metal is sent from the ladle 13 through the refractory ladle outlet shroud 14 to the tundish 15 and then through the metal feed nozzle 16 to the roll gap 17 of the casting roll 12. The high-temperature molten metal thus sent to the roll gap 17 forms a molten metal pool 20 on the roll gap 17, and this molten metal pool 20 is used for the casting roll 1
It is confined by a pair of side closure plates 18 at the two ends. The pair of side closing plates 18 are held on the stepped ends of the casting roll 12 by the operation of the pair of hydraulic cylinder devices 21. The top surface of the melt puddle 20 (commonly referred to as the “meniscus” level) may be set above the bottom end of the metal feed nozzle 16 so that the bottom end of the metal feed nozzle 16 is immersed in the melt puddle 20.

By cooling the casting rolls 12 with water, the metal shells are solidified on the surface of the moving casting rolls 12, and the metal shells are combined in the roll gap 17 to form a solidified strip product at the outlet of the casting rolls 12. make. The product can be fed to a standard coiler (not shown) for winding.

The twin roll casting machine exemplified and described above is
Australian Patent Nos. 631728 and 637548
And US Pat. Nos. 5,184,668 and 5,2.
77,243, which is similar to that illustrated and described in some detail. Reference may be made to those patents for appropriate structural details which do not form part of the invention.

In order to control casting accurately,
In order to avoid extreme fluctuations in the depth of the molten metal pool 20, it is desirable to continuously monitor the depth of the molten metal pool 20 and control the metal flow. This is problematic because the melt pool 20 is very hot and inaccessible. The molten metal pool 20 is formed in a very limited space between the casting rolls 12, and the access is almost completely achieved by the metal supply nozzle 16 and the nozzle fixture 22 that mounts the metal supply nozzle 16 at a predetermined position immediately above the roll gap 17. It is blocked.
However, according to the present invention, one end of the molten metal pool 20 is separated upward and the field of view of the molten metal pool 20 is increased.
It is possible to mount the optical inspection device 23 adjacent to the casting roll 12 and aligned so as to extend downwards along.

The optical inspection device 23 comprises a protective housing 2
4 can be a small video camera for industrial use housed in 4. As a suitable example of the video camera, Elmo MP481 Pal (Elmo MP manufactured by Elmo Co., Ltd. in Nagoya
There is a 481 PAL) CCD color video micro camera.

The area 27 on one surface of the casting roll 12 is taken in, whereby the surface of the molten metal pool 20 and the casting roll 1
The video camera 23 is connected to the metal supply nozzle 16 so as to have a field of view capable of monitoring the substantial movement of the intersection with the two surfaces.
Align along line of sight 25 to one side, above the pool 20, and below the nozzle fixture 22 to a very limited space. The field of view is indicated in FIG. 3 by the diverging dash-dotted line 26. Movement of the surface of the melt pool 20 can be monitored by an area extending along and around the casting roll 12.

The video camera 23 is laterally spaced from one side of the central longitudinal plane passing through the roll gap 17 and its field of view is on the same side of the central longitudinal plane as the video camera 23. The surface and the surface of the molten metal pool 20 are oriented and aligned so as to see the intersection, and the field of view is angled so as to face the central longitudinal plane.

In FIG. 3, continuous lines 31 show different depths of the pool 20 in equal depth increments. The movement of the surface of the molten metal pool 20 is observed by the video camera 23 as a movement of a line intersecting the field of view with the surface of the molten metal pool 20 and the casting surface of the casting roll 12. It is observed that as the depth of the melt pool 20 decreases, the movement of the boundary line across the field of view for even depth increments decreases due to the curvature of the casting roll 12. However, the video camera 2
Since 3 is aligned for viewing along the casting roll 12, such a "crowding" effect is such that if the field of view is oriented directly toward the surface of the casting roll 12 rather than at an angle as per the invention. Much smaller than that you would experience when combined. In order to monitor the depth of the molten metal pool 20 in a wide range, it is preferable to align the line of sight of the video camera 23 with an angle in the range of 15 ° to 35 ° with respect to the horizontal, and most preferably about 25 °. Good to do.

The video camera 23 sends signals via a cable 33 to a conventional signal processor and visual display screen (not shown). The display screen shows a video image of the boundary between the pool 20 and the casting roll 12 that moves across the display screen as the depth of the pool 20 changes. When setting the video camera 23, because of the camera angle and the orientation of the surface of the casting roll 12, the video image on the surface of the molten metal pool 20 is moved vertically rather than horizontally across the screen as usual. It may be preferable to rotate.

It is necessary to set a scale in order to associate the movement of the boundary between the molten metal pool 20 and the casting roll 12 with a specific molten metal pool depth. This can be easily performed by setting and supporting a plurality of measuring sheets having different widths exactly flat between the casting rolls 12 above the roll gap 17 and at a depth determined by the width before the casting operation. Can be achieved. The measuring sheet material can be coated in white so that the video camera 23 can easily find the boundary between one side of the measuring sheet material and the casting roll 12.
Given the size of the casting rolls 12 and the gap between the casting rolls 12, the width of the measurement sheet can be mathematically related to the depth of the pool 20, and the specific pool depth observed can be A suitable look-up table can be programmed into the signal processor software to determine the boundary position on the casting roll 12 it has.

As an alternative grading system, a laser is attached at a known height position, a projection angle is controlled to project a series of lines of a plurality of known heights, and these lines are continuously observed by a video camera. By doing so, it is possible to provide the required scale setting.

The apparatus disclosed above is merely an example, and various modifications can be made within the scope of the present invention. For example,
It is possible to monitor the depth of molten metal pool by installing multiple optical inspection devices such as video cameras. That is, a second video camera can be installed on the same end of the casting roll 12 as the video camera 23 and on the opposite side of the metal supply nozzle 16 to monitor the line of intersection between the melt pool 20 and the other casting roll. By copying this configuration to the opposite end of the molten metal pool 20, a total of four video cameras for monitoring the casting depth can be provided. These camera positions that can be added are shown by the dashed outline in FIG. The exact positioning and orientation of each video camera depends on the caster design and metal feed nozzle geometry.

[0022]

As described above, according to the present invention, it is possible to obtain an excellent effect that the depth of the molten metal pool can always be accurately monitored during the casting operation.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a twin roll casting machine equipped with a molten metal pool depth monitoring device in an example of an embodiment of the present invention.

FIG. 2 is a plan view of main components of a twin roll casting machine and a molten metal pool depth monitoring device, showing a position where a video camera of the molten metal pool depth monitoring device can be installed.

FIG. 3 is a view showing how the molten metal pool depth monitoring device according to the present invention monitors the molten metal pool depth during casting.

[Explanation of symbols]

 12 casting roll 17 roll gap 20 molten metal pool 23 optical inspection device (video camera) 25 line of sight 26 chain line 27 molten pool area on one surface of casting roll 12

 ─────────────────────────────────────────────────── ————————————————————————————————— Inventor Gary Kenneth Smith Australia New South Wales Seahampton Force Force 5 (72) Inventor Paul Raymond Osbourne Australia New South Wales Courambong Freeman's Drive 735

Claims (13)

[Claims] 1. A melt pool depth monitor for a twin roll casting machine, wherein a roll gap is formed between a pair of casting rolls, and a melt pool extending over the entire length of the roll gap is arranged on the roll gap. On the one side and adjacent to the casting roll so as to be spaced apart upward, and the visual field extends downward along the molten metal pool to see the intersection of the molten metal pool surface and one of the casting roll casting surfaces. And an optical inspection device aligned as described above, and a display device for displaying the movement of the intersection as a measure of the depth change of the molten metal pool. . 2. A molten metal pool depth monitoring device for a twin roll casting machine according to claim 1, wherein the optical inspection device is a video camera. 3. The molten metal pool of a twin roll casting machine according to claim 2, wherein the display device comprises a signal processing device for processing a signal from the video camera and a screen for displaying an inspection image obtained from the signal. Depth monitor device. 4. A casting roll casting wherein the optical inspection device is laterally spaced from one side of the central longitudinal plane passing through the roll gap and its field of view is on the same side of the central longitudinal plane as the optical inspection device. The molten pool depth monitor device for a twin roll casting machine according to any one of claims 1 to 3, wherein the twin roll casting machine is aligned so that the intersection between the surface and the surface of the molten pool can be seen. 5. The molten metal pool depth monitoring device for a twin roll casting machine according to claim 4, wherein the optical inspection device is aligned so that the field of view is an angle facing the central longitudinal plane. 6. The twin roll according to claim 1, wherein the field of view is arranged around the line of sight of the optical inspection device aligned at an angle of 15 ° to 35 ° with respect to the horizontal. Device for monitoring the depth of molten metal in the casting machine. 7. A method for monitoring the depth of a melt pool in a twin roll casting machine, wherein a roll gap is formed between a pair of casting rolls, and a melt pool extending over the entire length of the roll gap is arranged on the roll gap. During the casting operation, the casting surface area is located outside one end of the casting roll and is spaced apart from the one end of the casting roll. At the position aligned so that the view of the intersection between the molten metal pool surface and the casting roll casting surface can be seen, the optical inspection device is supported before casting work, and the movement of the intersecting part changes the molten metal pool depth. A method for monitoring the depth of molten metal pool in a twin roll casting machine, which is characterized in that it is displayed as a scale. 8. A casting roll casting surface and a molten metal pool in which the positioning is laterally spaced from one side of the central vertical plane of the roll gap and the field of view is on the same side of the central vertical plane as the optical inspection device. The method for monitoring the depth of a molten metal pool in a twin roll casting machine according to claim 7, wherein the optical inspection device is aligned so as to be oriented so that the intersection with the surface is viewed. 9. The method for monitoring the depth of a molten metal pool in a twin roll casting machine according to claim 8, wherein the optical inspection device is aligned so that the visual field is an angle facing the central longitudinal plane. 10. The optical inspection apparatus is coordinated in said positioning so that the visual field is arranged around a line of sight aligned at an angle in the range of 15 ° to 35 ° with respect to the horizontal.
10. The method for monitoring the depth of the molten metal pool in the twin roll casting machine according to any one of 9 to 9. 11. A scale by supporting and aligning the optical inspection device with said positioning prior to the casting operation and observing the optical inspection device as a series of positioning of a roll surface area of known height above the roll gap. The method for monitoring the depth of a molten metal pool in a twin roll casting machine according to any one of claims 7 to 10, which is defined. 12. Positioning by placing measuring sheets of different width between casting rolls at different heights above the roll gap and observing the line of intersection between the strips and the roll surface area. The method for monitoring the depth of molten metal pool in a twin roll casting machine according to claim 11, wherein 13. A method according to claim 11, wherein the positioning is established by projecting a series of line images onto a roll surface area and viewing the line images.