JP6319179B2 - Method for adjusting roll interval of slab support roll - Google Patents

Description

  The present invention relates to a method for adjusting the spacing of each set of slab support rolls in a roll segment used to support a slab cast in a continuous casting machine.

  In a continuous casting machine, molten steel stored in a tundish is caused to flow into a cooled mold, a solidified shell is formed near the inner wall of the mold to form a cast piece, and the cast piece is drawn out from the mold. The slab drawn from the mold is guided into the slab guide device, and solidified to complete while being cooled by the slab guide device. The slab guide device includes a slab support roll that is composed of two sets and arranged in parallel in the casting direction of the slab, and a roll segment that includes a plurality of sets of the slab support rolls.

  The roll segment includes a pair of opposed plate-like frames, a slab support roll that is rotatably attached to the opposed surfaces of the pair of frames, and a tie rod that connects the pair of frames. For example, a roll segment leaks to the slab support roll when a solidification delay occurs in the slab and the solidified shell becomes thin and breaks, and a steel leakage problem such as a breakout in which molten steel flows out of the broken part occurs. The molten steel is attached. In that case, it is necessary to replace the slab support roll. Since the plurality of slab support rolls provided in the roll segment can be exchanged in one operation, they are particularly arranged at and before the position where solidification of the slab is completed.

  The interval between the slab support rolls is an important management item in order to optimize the load applied to the solidified shell and prevent bulging and internal cracking of the slab. The distance FSi between the slab support rolls Ri of each set when supporting the slab, depending on the position where the slab support roll is disposed, the quality of the slab such as heat shrinkage due to the temperature effect of the slab It is desirable that the reference Bi is determined by (1) and the distance FSi be the distance of the reference Bi. The subscript i represents the slab support roll number of each set when the number of the slab support roll of the set closest to the mold is 1 in the casting direction of the slab.

  However, in the offline state in which the slab is not supported by the roll segment, even if the distance Si between the slab support rolls of each set is set as the distance of the reference Bi, by the static pressure of the molten steel (molten steel static pressure) in the slab, Since the interval FSi while the slab is supported by the roll segment is enlarged, it is not easy to adjust the interval FSi to the reference Bi distance. Therefore, in Patent Document 1, in consideration of the pressure corresponding to the molten steel static pressure during casting applied to each set of slab support rolls Ri in the roll segment, the pressure corresponding to the molten steel static pressure during casting is offline. When the slab support roll Ri of each set is loaded, the distance αi that is enlarged at the interval Si is obtained, and the distance αi is subtracted from the reference Bi to correct the off-line interval Si. ing.

JP 2003-112240 A

  In the method of adjusting the roll interval of the slab support roll in the roll segment described in Patent Document 1, when reproducing the pressure corresponding to the static pressure of molten steel during casting, the offline state in which the slab is not supported The slab support roll is loaded with a jack. This method reduces slab internal cracks. However, in this method, the situation where the load is applied is different from that at the time of casting, and the amount of expansion of the roll interval in a high-temperature atmosphere is not considered, and the slab is supported by the roll segment. As a method for bringing the interval FSi closer to the reference Bi, there is room for further improvement.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to support a slab that makes it possible to make the distance FSi of the slab support roll Ri when supporting the slab closer to the distance of the reference Bi. It is to provide a roll interval adjustment method for rolls.

The gist of the present invention for solving the above problems is as follows.
A slab comprising a pair of opposed plate-like frames and a roll that is rotatably attached to the opposing surfaces of the pair of frames, and supports a slab drawn from a mold of a continuous casting machine Each set of slab support in a roll segment, which is a support roll, the slab support roll Ri having a plurality of the sets arranged in parallel in the casting direction of the slab, and a tie rod connecting the pair of frames. A method of adjusting the interval between the rolls Ri, wherein an expansion amount Xi of the interval between the slab support rolls Ri due to the elongation of the tie rods when the slab is supported by the roll segment is obtained, and the casting due to the deflection of the frame The amount Yi of enlargement of the interval between the piece support rolls Ri is determined, a reference Bi is determined in advance for the interval between the slab support rolls Ri of each set during casting, and the slab is not supported. The slab of the slab support roll Ri of each set is a distance calculated by subtracting the sum of the enlargement amount Yi and the enlargement amount Xi from the reference Bi. Method for adjusting the roll interval of the support roll.
Here, the suffix i represents the slab support roll number of each set when the number of the slab support roll of the set closest to the mold in the casting direction of the slab is 1.

  In the present invention, in consideration of the frame bending due to the static pressure of the molten steel when supporting the slab and the heat received from the slab and the elongation of the tie rod, Since the interval Si between the slab support rolls Ri of the set is adjusted, the interval FSi between the slab support rolls Ri while supporting the slab can be made closer to the distance of the reference Bi. Thereby, generation | occurrence | production of the internal crack of a slab can be suppressed more reliably.

It is a figure which shows a vertical type continuous casting machine. It is a side view of the roll segment shown in FIG. It is a top view of the roll segment shown in FIG. It is a figure which shows the state after adjusting the roll space | interval Si of slab support roll R1 at the time of offline. It is a graph which shows the internal crack index | exponent of the slab in an Example.

  The present invention comprises a pair of opposing plate-like frames and a roll rotatably attached to the opposing surfaces of the pair of frames, and a plurality of such sets are arranged in parallel in the casting direction of the slab. The slab is not supported while off-line while the high-temperature slab is supported by the roll segment having the slab support roll Ri and the tie rod connecting the pair of frames. The distance Si between each set of slab support rolls Ri, which was set as the distance of the reference Bi in the state, is set to a distance obtained by subtracting, from the reference Bi, the distance that is extended when the slab is supported by the roll segment. The main focus is that. That is, according to the present invention, the interval Si between the slab support rolls Ri of each set when the slab is not supported is determined from the reference Bi and the tie rod elongation caused when the slab is supported by the roll segment. The distance obtained by subtracting the sum of the enlargement amount Xi of the single support roll Ri and the enlargement amount Yi resulting from the bending of the frame is used.

  An example of an embodiment of the present invention will be described with reference to FIG. 1 showing a vertical continuous casting machine that supports a slab cast in a continuous casting process of steel by a roll segment. The vertical continuous casting machine 1 includes a mold 5, a tundish 2 installed above the mold 5, a plurality of cast piece support rolls 6 arranged below the mold 5, and a roll segment 15. . Although not shown in the drawing, a ladle for containing the molten steel 9 is installed above the tundish 2, and the molten steel 9 is poured into the tundish 2 from the bottom of the ladle. An immersion nozzle 4 to which a sliding nozzle 3 is attached is installed at the bottom of the tundish 2, and the molten steel 9 is attached to the mold 5 through the immersion nozzle 4 in a state where a predetermined amount of the molten steel 9 stays in the tundish 2. Injected. A cooling water channel is formed in the mold 5, and the cooling water is passed through the cooling water channel. As a result, the molten steel 9 is extracted from the inner surface of the mold 5 and solidified to form a solidified shell 11, and the solidified shell 11 is extracted to form a slab 10 having an unsolidified layer 12 made of the molten steel 9 therein. .

  Although not shown in the drawings, a plurality of secondary cooling zones in which spray nozzles are arranged are installed in the gap between the slab support rolls 6 adjacent in the casting direction along the casting direction from directly below the mold 5. . The slab 10 is cooled while being drawn out by the cooling water sprayed from the spray nozzle. While the slab 10 is conveyed by the slab support roll 6 and passes through a plurality of secondary cooling zones, the solidified shell 11 is appropriately cooled, and solidification of the unsolidified layer 12 proceeds. Coagulation of is completed. A position at which solidification of the slab 10 is completed is referred to as a solidification completion position 13.

  A plurality of slab support rolls 6 are arranged downstream of the solidification completion position 13 so that the slab 10 is curved. In FIG. 1, a plurality of sets of slab support rolls 6 are arranged in the curved portion of the slab 10, but depending on the continuous casting machine 1, one bending roll is provided on the lower surface side of the slab 10 in the transport direction. Bending rolls may be set so that a plurality of them are arranged in parallel. Downstream from the end point of the curved portion, the slab support roll 6 is provided with a plurality of slab support rolls 6 so as to straighten the curved slab 10 into a straight shape. Furthermore, a plurality of transport rolls 7 are installed downstream, and a slab cutting machine 8 for cutting the slab 10 is disposed above the transport rolls 7. The slab 10 is cut into a slab 10 a having a predetermined length by a slab cutting machine 8.

  In the range from the outlet of the mold 5 to the solidification completion position 13, a roll segment 15 is installed. The roll segment 15 is a slab support in which a pair of opposed plate-like frames 16L and 16R and a roll attached to the opposed surfaces of the pair are arranged in parallel in the casting direction. A roll Ri. The slab support roll Ri is the same as the slab support roll 6 and transports the slab support roll Ri while sandwiching the slab 10 therebetween. For example, when a steel leakage trouble such as breakout occurs, the slab support roll Ri needs to be replaced. All the slab support rolls 6 attached to the roll segment 15 can be exchanged by one operation only by exchanging one roll segment 15, and the exchange becomes easy. Therefore, the roll segment 15 is particularly arranged in the range from the outlet of the mold 5 to the solidification completion position 13.

  The subscript i of the slab support roll Ri indicates each set when the number of the slab support roll 6 of the group closest to the mold 5 is 1 in one roll segment 15 in the casting direction of the slab. For example, the symbol R1 shown in FIG. 1 is closest to the mold 5 in the second roll segment 15 from the mold 5 in the downstream direction in the casting direction (first from the mold side). A set of slab support rolls 6 is shown.

  The side surface of one roll segment 15 in FIG. 1 is shown in FIG. Five sets of slab support rolls R <b> 1 to R <b> 5 are attached to opposing surfaces of the pair of frames 16 </ b> L and 16 </ b> R via a roll chock 21. The roll segment 15 has a pair of a frame 16L and a frame 16R, and further a tie rod 17 that passes through and connects the frame 16L and the frame 16R. A worm jack 19 is installed on the tie rod 17, and a disc spring 18 is installed between the worm jack 19 and the frame 16R. The roll chock 21 holding the slab support rolls R1 to R5 rotatably is fixed to the frame 16L or the frame 16R with a fixture such as a screw 21a with a plate-like shim 22 sandwiched therebetween.

  The worm jack 19 can be moved to narrow or widen the distance between the frame 16L and the frame 16R, and the intervals FS1 to FS5 of the slab support rolls R1 to R5 in a state where the slab 10 is supported are collectively shown. Can be adjusted. Moreover, the roll chock 21 holding each set of slab support rolls R1 to R5 is removed from the frame 16L and the frame 16R, and a plurality of shims 22 are appropriately added or the thickness of the shim 22 is changed. Each of the intervals FS1 to FS5 can be appropriately changed. Note that the slab 10 is changed by changing the intervals S1 to S5 (see FIG. 5 for S1) of the slab support rolls R1 to R5 in a state where the slab is not supported, such as when offline or when continuous casting is stopped. It is possible to adjust the intervals FS1 to FS5 in the state in which the is supported.

  The spacing FSi (FS1 to FS5) between the slab support rolls Ri (R1 to R5) optimizes the load applied to the solidified shell 11, and prevents bulging, internal cracking of the slab and center segregation of the slab. Is an important management item. The interval FSi between the slab support rolls Ri of each set while the slab is supported by the roll segment is determined by the quality of the slab 10 according to the position where the slab support roll 6 is disposed. It is desirable that the distance is Bi. The reference Bi is determined so as to compensate for the solidification shrinkage amount of the slab calculated from various operation parameters such as the mold size, the cooling water amount, and the casting speed. In FIG. 2, the intervals FS1 to FS5 are all shown to be the same, but the intervals FS1 to FS5 are often different from each other.

  During casting, the worm jack 19 is self-locked by the molten steel static pressure of the slab 10 having an unsolidified layer, whereby the frames 16R and 16L and the tie rod 17 are cast via the slab support rolls R1 to R5. It resists the bulging force of the piece 10. In addition, when a load load greater than a predetermined load does not act on the disc spring 18 installed on the tie rod 17, the disc spring 18 does not contract and exhibits a certain height, but the predetermined load load is When it acts, it starts to contract, and after exceeding a predetermined load, it is configured to contract in proportion to the load. Although omitted in FIG. 2, while the slab 10 is supported by the roll segment 15, the frames 16 </ b> L and 16 </ b> R are bent, and the tie rod 17 is extended along with the bending. By contracting 18, the bending of the frames 16 </ b> L and 16 </ b> R and the extension of the tie rod 17 are suppressed to some extent, and the shape of the roll segment 15 is maintained. Although FIG. 2 shows a form in which the disc spring 18 is installed on the tie rod 17 as the roll segment 15, the disc spring 18 is not necessarily installed on the tie rod 17.

  A plan view of the roll segment shown in FIG. 2 is shown in FIG. In FIG. 3, in order to simplify the description, the slab support roll of only R1 among the slab support rolls R1 to R5 is shown. Further, in FIG. 3, (a) shows an off-line roll segment 15 that does not support the slab, and shows a state in which the interval S1 of the slab support roll R1 is a distance of the reference B1. b) shows the state of the slab support roll R1 when the slab is supported in a state where the distance S1 is set as the distance of the reference B1, but the slab 10 is omitted.

When the slab is supported by the roll segment 15, the slab support roll R1 is pushed by the molten steel static pressure of the slab 10 as shown in FIG. With the fixed portion as the fixed end, it is bent so as to protrude in the direction opposite to the slab support roll R1, and in addition, the tie rod 17 is protruded toward the slab side by being pulled by the bending frames 16L and 16R. The tie rod 17 is curved and extended. The tie rod 17 is curved and approaches the slab 10 having a high temperature, and the tie rod 17 is further easily extended by heat from the slab 10.

  Furthermore, the slab support roll R1 moves at the position where the slab support roll R1 is attached due to the bending of the left frame 16L. As can be seen from comparison with FIGS. 3 (a) and 3 (b), the amount of increase in the interval due to the deflection of the frame 16L is the distance Y1L, and the amount of increase in the interval of the slab support roll R1 due to the deflection of the frame 16R on the right side of the page is Distance Y1R. Therefore, the enlargement amount Y1 of the interval between the pair of slab support rolls R1 due to the bending of the frames 16L and 16R becomes the distance (Y1L + Y1R). Further, the expansion amount of the interval between the slab support rolls R1 attached to the frame 16L due to the elongation of the tie rod 17 is the distance X1L, and the expansion amount of the interval between the slab support rolls R1 attached to the frame 16R is the distance. X1R. The distance X1 of the distance between the pair of slab support rolls R1 due to the extension of the tie rods 17 is a distance (X1L + X1R).

  The interval FS1 of the slab support roll R1 when the slab is supported in the state where the interval S1 of the slab support roll R1 is set to the distance of the reference B1 in the roll segment 15 when the slab is not supported is, Due to the bending of the frames 16L and 16R and the extension of the tie rod 17, the total increase amount (X1 + Y1) of the distance between the pair of slab support rolls R1 is increased from the reference B1. In consideration of the total amount, in the present invention, in the roll segment 15 when the slab is not supported, the interval S1 of the slab support roll R1 is calculated by subtracting the total amount (X1 + Y1) from the reference B1. By setting the distance, when the slab is actually supported by the roll segment 15, the FS1 of the slab support B is the distance of the reference B1.

  FIG. 4 shows a roll segment in a state in which the interval S1 of the slab support roll R1 when offline is a distance calculated by subtracting the total (X1 + Y1) from the reference B1. In FIG. 4, the off-line interval S1 of only the slab support roll R1 is shown, but the frames 16L and 16R are bent at the positions where the slab support rolls R2 to R5 (see FIG. 2) are attached. If the enlargement amounts Y2 to Y5 of the slab support rolls R2 to R5 resulting from the above are obtained, the setting values for offline can be obtained for the intervals S2 to S5 as well as the intervals S1 for offline.

  The amount of expansion of the interval between the slab support rolls Ri due to the extension of the tie rods 17 during actual casting is obtained by measuring the extension amount of the tie rods 17 when the slab 10 (see FIG. 1) is supported by the roll segments 15. be able to. Although illustration is omitted, through holes are formed in the frames 16L and 16R, the tie rods 17 are exposed through the through holes, a strain gauge is attached to the exposed portion of the tie rods 17, and the strain gauges Elongation can be measured. As a result, the strain gauge is covered with the frames 16L and 16R, and the measurement error due to heat from the slab 10 can be minimized. Further, the amount of elongation of the tie rod 17 when the high-temperature cast slab 10 to be cast is supported by the roll segment 15 may be calculated by FEM analysis.

  Further, by measuring the amount of bending of the frames 16L and 16R at the position where each of the slab support rolls Ri is mounted when the slab 10 is supported by the roll segment 15, the casting due to the bending of the frames 16L and 16R is measured. An enlargement amount Yi of the interval between the single support rolls Ri can be obtained. For example, the deflection amount of the frames 16L and 16R at an arbitrary position when the slab 10 is supported by the roll segment 15 can be measured by an optical sensor.

  As described above, if the elongation of the tie rod 17 is measured, an enlarged amount Xi of the interval between the slab support rolls Ri at the positions where the slab support rolls Ri are attached to the frames 16L and 16R can be obtained. . The tie rod 17 is more susceptible to radiation from the slab for bending and elongation than the frames 16L and 16R. It is important to measure the elongation of the tie rod when it is actually cast by attaching a strain gauge to the tie rod for the elongation when the slab is supported. The frame is located behind the roll, is less affected by radiation from the slab, and the amount of deflection does not change greatly between the slab support state and the off-line state. However, since the tie rod is more affected by radiation from the slab than the frame, the amount of elongation varies greatly. Therefore, the amount of elongation varies greatly between the slab support state and the off-line state, and when correcting the interval Si of the roll Ri, it is caused by the elongation of the tie rod 17 in a high temperature atmosphere when supporting the slab 10. It is effective to know the amount of expansion of the interval to be performed.

  Further, by FEM analysis, the amount of bending of the frames 16L and 16R at an arbitrary position under the condition that the hot slab 10 to be cast is supported by the roll segment 15 and the distance between the frames 16L and 16R due to the extension of the tie rod 17 are increased. The amount may be calculated. In the FEM analysis, a distributed load received by the roll is calculated based on the operation conditions, and a load acting on the segment frame is set. Moreover, if it determines from the installation method and segment structure of a real machine, a constraint condition will be given and it will analyze. Since the load from the slab is transmitted to the segment frame via the roll bearing, the maximum deflection is generated on the bearing seat surface of the segment frame. The displacement of the frame bearing seat may be adopted as a total value (Xi + Yi) of the amount of expansion of the interval caused by frame deflection and tie rod elongation.

  In this embodiment, the roll segment 15 is configured by arranging five sets of slab support rolls 6 in parallel in the casting direction. In particular, the set of slab support rolls 6 installed on the roll segment 15 is configured. The number is not particularly limited. Further, in the vertical continuous casting machine 1 shown in FIG. 1, four roll segments are arranged, but the number of bases is not particularly limited.

  In the said embodiment, although the structure of the roll segment 15 used with the vertical type continuous casting machine 1 is demonstrated, this invention is the roll space | interval of the slab support roll which the roll segment used with a vertical type continuous casting machine has. The present invention is not limited to the adjustment, and can be applied to, for example, adjustment of the roll interval of the slab support roll included in the roll segment used in the curved continuous casting machine.

  As described above, in the present invention, in consideration of the frame deflection caused by the heat received from the slab when the slab is supported and the elongation of the tie rod, the spacing Si between the slab support rolls Ri of each set in the offline state. Therefore, the interval FSi of the slab support roll Ri in the roll segment supporting the slab can be made closer to the distance of the reference Bi. Thereby, generation | occurrence | production of the internal crack of a slab can be suppressed more reliably.

  In order to verify the effect of the present invention, continuous casting of steel was performed a plurality of times using the vertical continuous casting machine 1 shown in FIG. In half the operation, among all the roll segments 15 used in the vertical continuous casting machine 1, the interval Si described above in the embodiment is increased from the reference Bi to the interval Si between the slab support rolls Ri of each set when offline. The distance calculated by subtracting the sum of Yi and the amount of expansion Xi was used as the distance (example of the present invention: taking into account the amount of expansion of the spacing Si due to the extension of the tie rod due to the heat of the slab). In the remaining half of the operation other than the example of the present invention, when a pressure corresponding to the static pressure of the molten steel being cast is applied to each set of slab support rolls Ri in an off-line state, a distance αi that is increased at the interval Si is obtained. Further, the dummy bar holding pressure at the time of inserting the dummy bar of each segment is applied to each segment offline, the amount of expansion βi of each set of slab support rolls Ri is measured, and the value obtained by subtracting the distance αi from the reference Bi The steel was continuously cast in the same manner as the example of the present invention except that the value obtained by adding the expansion amount βi to the off-line interval Si (Comparative example: interval due to tie rod extension due to heat of slab) (Without considering the amount of Si expansion).

  In both the inventive examples and the comparative examples, the obtained slabs were polished, pickled, and the number of internal cracks in the slabs was measured visually. FIG. 5 shows an index of the number of internal cracks in the slab of the present invention when the number of slabs obtained in the comparative examples is 1. The internal crack index of the slab of the present invention example is 0.3, and the interval FSi of the slab support roll Ri in the roll segment supporting the slab is made closer to the distance of the reference Bi than the comparative example, It turns out that the internal crack of the slab was effectively prevented.

DESCRIPTION OF SYMBOLS 1 Vertical type continuous casting machine 2 Tundish 3 Sliding nozzle 4 Immersion nozzle 5 Mold 6 Casting piece support roll 7 Conveying roll 8 Casting piece cutting machine 9 Molten steel 10 Casting piece 10a Casting piece (after cutting)
11 Solidified shell 12 Unsolidified layer 13 Solidification completion position 15 Roll segment 16L Frame (left side of paper)
16R frame (right side of paper)
17 Tie rod 18 Disc spring 19 Worm jack 21 Roll chock 21a Screw (Mounting tool)
22 Shim Each slab support roll in the Ri roll segment R1 The first slab support roll closest to the mold in the roll segment Si Interval between each slab support roll when the Si slab is not supported Roll interval of each set of slab support rolls when supporting FSi slabs Bi Standard of roll interval of each set of slab support rolls

Claims (1)

A pair of opposing plate-like frames;
A pair of slab support rolls configured to support a slab drawn from a mold of a continuous casting machine, the rolls being rotatably attached to opposing surfaces of the pair of frames. Slab support rolls Ri arranged in parallel in the casting direction of
A method of adjusting a distance between each set of slab support rolls Ri in a roll segment having a tie rod connecting the pair of frames,
The sum of the expansion amount Yi for the expansion amount and Xi distance of said slab support rolls Ri by elongation of the tie rod, the slab spacing support rolls Ri due to deflection of the frame when supporting a cast slab in the roll segment The value (Xi + Yi) is obtained by FEM analysis of the displacement of the frame bearing seat surface ,
A reference Bi for the interval between the slab support rolls Ri of each set during casting is determined in advance,
The interval Si between the slab support rolls Ri of each set when the slab is not supported is calculated by subtracting the sum (Xi + Yi) of the enlargement amount Yi and the enlargement amount Xi from the reference Bi. A method for adjusting a roll interval of a slab support roll, characterized in that the distance is adjusted.
Here, the suffix i represents the slab support roll number of each set when the number of the slab support roll of the set closest to the mold in the casting direction of the slab is 1.

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