JP2018075615A - Rolling equipment and rolling method - Google Patents

Abstract

The present invention provides a rolling apparatus capable of suppressing meandering in an in-line mill when the thin-walled slab cast by a twin drum type thin-wall slab continuous casting apparatus is sent to an in-line mill for rolling. A rolling facility for rolling a slab cast by a twin drum type continuous casting machine with a pair of work rolls, each work roll being on one end side in the roll axial direction and having one end in the roll axial direction. A diameter-enlarged portion that expands from the other end side to the other end side, a diameter-reduced portion that is located on the other end side in the roll axis direction and that decreases in diameter from one end side to the other end in the roll axis direction, and An intermediate portion that is between the diameter portion and the diameter-expanded portion side from the diameter-expanded portion side to the diameter-reduced portion side, and then the diameter of the roll is maximized at the boundary between the diameter-expanded portion and the intermediate portion. The roll profile has a minimum at the portion and a maximum at the boundary between the intermediate portion and the reduced diameter portion, and is disposed symmetrically with respect to the point and in a relatively movable manner in the roll axis direction. [Selection] Figure 4

Description

  The present invention relates to a rolling facility for rolling a slab cast by a twin drum type continuous casting apparatus with a pair of work rolls, and a rolling method using the rolling equipment.

  In the twin-drum type continuous casting apparatus, a molten metal reservoir is formed by a pair of continuous casting cooling drums (hereinafter referred to as “cooling drums”) and side dams arranged opposite to each other in the horizontal direction. A pair of cooling drums is rotated with the stored molten metal to cast a thin cast piece (hereinafter referred to as “casting strip”) (for example, Patent Document 1). When the molten metal is stored in the molten metal reservoir, the cooling drums are rotated downward from above, respectively, and the molten metal is sent down as a cast strip while solidifying and growing on the peripheral surface of the cooling drum. The cast strip fed from the cooling drum is fed horizontally by a pinch roll and adjusted to a desired plate thickness by a downstream in-line mill. The cast strip whose thickness is adjusted by the in-line mill is wound into a coil by a winding device installed downstream of the in-line mill.

  In such a twin-drum type continuous casting apparatus, the cooling drum is generally at a low temperature before the start of casting, and when the casting is started, the temperature is raised by contact with the molten metal. Further, the cooling drum is cooled from the inner surface by a cooling medium (for example, cooling water) so as not to exceed a predetermined temperature. Hereinafter, the period when the temperature of the cooling drum reaches a predetermined temperature and becomes constant is the steady casting period, the arbitrary point in the steady casting period is the steady casting, and the temperature of the cooling drum in the steady casting period is the steady temperature . The state during the steady casting period is referred to as a steady state.

  The profile of the cooling drum changes over time from the start of casting until it reaches a steady state. For this reason, the profile of the cooling drum is set so that the plate profile (plate crown) of the cast strip at the time of steady casting becomes a desired plate profile.

  Here, FIG. 8 shows changes in the profiles of the cooling drums 10a and 10b and the plate profile of the casting strip S with the elapsed time from the start of casting when the casting strip S is manufactured by the conventional twin drum type continuous casting apparatus. Show. In addition, the plate profile of the casting strip S shows the state before carrying out the reduction in the in-line mill.

  The cooling drums 10a and 10b at the start of casting are set to have a concave profile in which the center in the axial direction is recessed as shown in the state A of FIG. The cast strip S rolled by the cooling drums 10a and 10b having such a profile has a plate profile whose center in the plate width direction (that is, the axial direction) is convex.

  Next, after a while from the start of casting, the cooling drums 10a and 10b expand (expand) in the center in the axial direction due to heat input from the molten metal, and as shown in state B in FIG. It changes to a concave profile smaller than the time (state A). For this reason, the plate profile of the casting strip S has a convex shape with a smaller crown amount than the casting strip S at the start of casting (state A).

  Thereafter, after a further time has elapsed from the start of casting and reached a steady state, the cooling drums 10a and 10b are further expanded (expanded diameter) by heat input from the molten metal, and are shown in a state C in FIG. Thus, the hollow at the center in the axial direction changes to a slightly concave profile. Therefore, the plate profile of the cast strip S has a convex shape with a smaller crown amount than in the state B.

  The time required to reach state C from state A in FIG. 8 varies depending on the steel type (melting temperature) of the molten metal, the thickness of the casting strip, the rotation speed of the cooling drum and the cooling efficiency, but is approximately about from the start of casting. About 30 seconds.

  On the other hand, the change in the plate profile of the casting strip S is caused not only by the change due to the thermal expansion of the cooling drum, but also by the change in the growth of the solidified shell due to the non-uniform cooling of the cooling drum from the start of casting until the steady temperature is reached. . Generally, if the molten metal is strongly cooled by the cooling drum, the thickness of the solidified shell is increased and the thickness of the cast strip S is increased. At this time, the cooling efficiency of the molten metal by the cooling drum is higher at the end than in the center in the axial direction of the cooling drum. Therefore, the thickness of the solidified shell is greater at the plate end than at the center of the plate of the cast strip S. As a result, in the cast strip S after the start of casting, the plate thickness at the plate end is thicker than the plate thickness at the plate center. The portion where the plate thickness is thick is called edge-up. The amount of edge up is greatest at the start of casting, decreases with the elapsed time after the start of casting, and is almost eliminated during steady casting.

  FIG. 9 is a conceptual diagram showing a change in the plate profile of the cast strip S caused by the change in the growth of the solidified shell until the cooling drum reaches the steady temperature when the cast strip is manufactured by the twin drum type continuous casting apparatus. is there. In FIG. 9, the cooling drum is not shown.

  Immediately after the start of casting, heat is more likely to escape at the end than at the axial center of the cooling drum. Accordingly, the molten metal is greatly cooled at the width direction end portion of the cast strip S, and the solidified shell is formed thicker at the width direction end portion than the width direction center portion of the cast strip S. As a result, the plate profile of the cast strip S immediately after the start of casting has a large edge-up Sa at the width direction end as shown in state A in FIG.

  After a while after the start of casting, the temperature difference between the center and the end in the axial direction of the cooling drum becomes smaller than at the start of casting. For this reason, the cooling of the molten metal at the end in the width direction of the casting strip S is weaker than at the start of casting, and the difference in thickness between the central portion and the end in the width direction of the solidified shell is smaller than at the start of casting. As a result, as shown in state B of FIG. 9, the plate profile of the casting strip S at the time when the casting has started for a while, the edge-up Sa at the width direction end is smaller than immediately after the start of casting (state A). .

  After a lapse of time from the start of casting and reaching a steady state, the temperature difference between the axial center portion and the end portion of the cooling drum is further reduced, and the solidified shell in the width direction center portion and the end portion is further reduced. There is almost no difference in thickness. As a result, the plate profile of the cast strip S after reaching the steady state after a lapse of time from the start of casting, as shown in state C in FIG.

  The time required to reach state C from state A in FIG. 9 varies depending on the steel type (melting temperature) of the molten metal, the thickness of the casting strip, the rotational speed of the cooling drum and the cooling efficiency, but state A in FIG. Is almost the same as in the case of the state C, and is about 30 seconds from the start of casting.

  As described above, the plate profile of the casting strip S from the start of casting to the time of steady casting is a combination of the crown change due to the thermal expansion of the cooling drum and the edge-up change due to the uneven cooling of the cooling drum. That is, as shown in FIG. 10, the plate profile of the casting strip S is in a state where the plate thickness at the central portion in the width direction and both ends is thick as shown in state A immediately after the start of casting, and after some time has elapsed after the start of casting. As shown in B, the deviation of the plate thickness in the width direction decreases, and after that, when the steady state is reached, the plate thickness becomes substantially uniform as shown in state C.

  Here, when the cast strip cast by the twin-drum type continuous casting equipment is rolled by an in-line mill as in Patent Document 1, the temperature of the cast strip is about 1000 ° C. on the inlet side of the in-line mill. Therefore, it is possible to slightly adjust the plate crown by causing a metal flow (width expansion) in the plate width direction in the cast strip. Examples of the in-line mill include a six-high rolling mill having an intermediate roll shift mechanism and a four-high rolling mill having a work roll cross mechanism.

  Further, in Patent Document 2, as an in-line mill of a twin roll continuous casting facility in which a pair of casting rolls are arranged horizontally in parallel, a four-stage having a pair of rolling rolls having an S-shaped roll profile and having a shift mechanism. A rolling mill is disclosed. In such a rolling mill, it is disclosed that the plate crown can be changed from a convex shape to a concave shape by roll shift, and that it is possible to cope with the asymmetry of the material plate crown by realizing the asymmetry of the roll shift.

JP 2000-343103 A JP 2004-50221 A

  However, the in-line mills described in Patent Documents 1 and 2 can cope with simple shape control of the middle extension and end extension, but as shown in the state A and the state B in FIG. It is difficult to control the plate crown of a cast strip having a plate profile with increased thickness at both ends.

  Further, in the in-line mill, when the cast strip having the plate profile as shown in the state A or the state B in FIG. 10 is rolled with such a large force that the crown amount is adjusted, the plate center portion and the plate end portion have the plate thickness. Is thick, it causes a large elongation in the longitudinal direction, and the middle elongation at the center of the plate and the end elongation at the end of the plate become extremely large. As a result, meandering and squeezing occur and the cast strip is easily broken. When the casting strip breaks, the molten metal remaining in the molten metal reservoir is immediately discarded, resulting in a significant yield reduction.

  On the other hand, the cast strip until the desired plate thickness is obtained by the in-line mill is generally cut off in a subsequent process as off-gauge (out of plate thickness) and processed as scrap. As a result, casting strip off-gauge is a major factor in reducing casting strip yield and increasing manufacturing costs. Therefore, it is desirable that the thickness of the cast strip in the in-line mill reaches the desired thickness as soon as possible. That is, in order to start a flying touch in an in-line mill earlier and to stably and efficiently roll the cast strip to a desired thickness, a cast strip having a plate profile as shown in state A in FIG. When rolling with an in-line mill, it is necessary to prevent meandering and plate breakage.

  However, as described above, since it is difficult to control the plate crown of the cast strip having the plate profile in which the plate thickness between the center portion in the width direction and both ends is increased in the conventional technique, the flying touch is in a steady state. After that, it must be started, and an off-gauge is generated, resulting in an increase in cost.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to meander when a cast strip cast by a twin drum type continuous casting apparatus is sent to an in-line mill for rolling. It is an object of the present invention to provide a new and improved rolling equipment and rolling method capable of preventing the occurrence of squeezing and speeding up the flying touch.

  The inventors of the present invention stably roll while suppressing meandering in an in-line mill when a cast strip, which is a thin slab cast by a twin drum type continuous casting apparatus, is sent to an in-line mill for rolling. As a result of earnestly researching the technology for this purpose, a special roll profile is given to the pair of work rolls constituting the in-line mill, and the gap formed by the work rolls is changed with the elapsed time after the start of casting. It was conceived that the work roll was moved in the roll axis direction in accordance with the plate profile. This makes it possible to change the roll profile in accordance with the plate profile of the cast strip, and the cast strip can be rolled uniformly and without meandering or plate shape defects, and the timing of the flying touch can be advanced. It was also found to be effective.

  That is, in order to solve the above-mentioned problem, according to a certain aspect of the present invention, a rolling facility for rolling a slab cast by a twin drum type continuous casting apparatus with a pair of work rolls, A diameter-increased portion that is on one end side in the roll axis direction and expands from one end in the roll axis direction toward the other end side, and is located on the other end side in the roll axis direction and from one end side to the other end in the roll axis direction. The diameter of the roll is reduced, and the intermediate portion between the diameter-expanded portion and the diameter-reduced portion and the diameter-increased portion from the diameter-expanded portion side toward the diameter-reduced portion side. The roll profile has a maximum at the boundary between the enlarged diameter part and the intermediate part, a minimum at the intermediate part, and a maximum at the boundary part between the intermediate part and the reduced diameter part. A rolling facility is provided which is arranged to be relatively movable.

  Moreover, a rolling installation is provided with a pair of backup roll which supports a pair of work roll, and the trunk | drum length of a backup roll is set shorter than the plate | board width of the slab rolled by a pair of work roll.

  Furthermore, a roll shift control unit that controls the relative position of each work roll in the roll axis direction based on a time change of a plate profile of a slab cast by a twin drum type continuous casting apparatus acquired in advance may be provided. .

  In addition, at least one of the rolling direction entry side and the exit side of the rolling equipment is provided with a position detection device that detects the plate width direction position of the slab, and the slab width direction position detected by the position detection device A roll shift control unit for controlling the relative position of each work roll in the roll axis direction may be provided so as to sandwich the slab symmetrically with respect to the center position in the plate width direction.

  Moreover, in order to solve the above-mentioned problem, according to another aspect of the present invention, there is provided a rolling method in which a slab cast by a twin drum type continuous casting apparatus is rolled by a rolling facility having a pair of work rolls, Each work roll is located on one end side in the roll axis direction and has a diameter-expanding portion that expands from one end in the roll axis direction toward the other end side, and one end in the roll axis direction on the other end side in the roll axis direction A diameter-reduced portion that is diameter-reduced from the side toward the other end, and an intermediate portion that is between the diameter-reduced portion and the diameter-reduced portion and is diameter-reduced from the diameter-reduced portion side toward the diameter-reduced portion side It has a roll profile where the roll diameter is maximal at the boundary between the enlarged diameter part and the intermediate part, is minimal at the intermediate part, and is maximal at the boundary part between the intermediate part and the reduced diameter part. In addition, it is arranged so as to be relatively movable in the roll axis direction. The time change of the plate profile of the slab cast by the continuous casting apparatus is calculated, and the work roll is relatively moved in the roll axis direction based on the pre-calculated time change of the plate profile of the slab. A rolling method is provided.

  Furthermore, the work roll is relatively moved in the roll axis direction based on the time change of the plate profile of the slab obtained in advance, and is disposed on at least one of the rolling direction entry side and the exit side of the rolling equipment. The position detection device detects the position of the slab in the plate width direction, and the slab is sandwiched symmetrically with respect to the center position in the plate width direction based on the position of the slab in the plate width direction detected by the position detection device. In addition, the relative position of each work roll in the roll axis direction may be controlled.

  The rolling based on the plate profile of the slab includes a first stage in which the slab is rolled at the diameter-expanded portion and the intermediate portion of each work roll, and a minimum portion where the roll diameter is minimum at the intermediate portion of each work roll. You may include the 2nd step which rolls a slab in the said intermediate part, and the 3rd step which rolls a slab in the part by the side of a reduced diameter part rather than a minimum part among the intermediate parts of each work roll.

  Moreover, you may further include the 4th step which rolls a slab after the 3rd step by the part and diameter reduction part of a diameter reduction part side from the minimum part among the intermediate parts of each work roll.

  According to the present invention, when a cast strip cast by a twin-drum type continuous casting apparatus is sent to an in-line mill and rolled, it is possible to prevent meandering and squeezing and to speed up the flying touch.

It is explanatory drawing which shows schematic structure of the manufacturing process of the casting strip which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the connection part of the front-end | tip of a casting strip at the time of the rolling start which concerns on the same embodiment, and a dummy sheet | seat. It is explanatory drawing which shows the structure of the in-line mill control apparatus which controls an in-line mill. It is explanatory drawing which shows the shape of the work roll of the in-line mill which concerns on the same embodiment. It is explanatory drawing explaining the rolling process of the casting strip by the work roll of the in-line mill which concerns on the same embodiment. It is explanatory drawing which shows the structure of the in-line mill control apparatus 90 which controls the in-line mill which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the work roll and backup roll which comprise the in-line mill which concerns on the same embodiment. It is a conceptual diagram which shows the change of the profile of a cooling drum and the plate profile of a casting strip with the elapsed time from the casting start at the time of manufacturing a casting strip with the conventional twin drum type continuous casting apparatus. It is a conceptual diagram which shows the change of the plate profile of a casting strip resulting from the growth change of the solidification shell until a cooling drum reaches | attains steady temperature when manufacturing a casting strip with a twin drum type continuous casting apparatus. It is a conceptual diagram showing the change in the plate profile of the casting strip from the start of casting to the time of steady casting, taking into account the change caused by the crown change due to the thermal expansion of the cooling drum and the edge-up change due to the uneven cooling of the cooling drum. .

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. First Embodiment>
[1-1. Casting strip manufacturing process]
First, based on FIGS. 1-3, the outline | summary of the manufacturing process which manufactures the casting strip which concerns on the 1st Embodiment of this invention is demonstrated. FIG. 1 is an explanatory view showing a schematic configuration of a manufacturing process of a casting strip (thin cast piece) according to the present embodiment. FIG. 2 is an explanatory view showing a connection portion between the tip of the casting strip S and the dummy sheet 11 at the start of rolling. FIG. 3 is an explanatory diagram showing a configuration of an inline mill control device 90 that controls the inline mill 50.

  As shown in FIG. 1, the cast strip manufacturing process 1 according to the present embodiment includes, for example, a tundish (storage device) T, a twin drum continuous casting facility 10, an antioxidant device 20, a cooling device 30, A first pinch roll device 40, an inline mill 50, a second pinch roll device 60, and a winding device 70 are provided.

  As shown in FIG. 1, the twin-drum continuous casting apparatus 10 includes, for example, a pair of cooling drums 10a and 10b and side weirs (not shown) arranged on both sides in the axial direction of the pair of cooling drums 10a and 10b. With. The pair of cooling drums 10 a and 10 b and the side dam constitute a molten metal storage unit 15 that stores the molten metal supplied from the tundish T.

  The pair of cooling drums 10a and 10b includes a first cooling drum 10a and a second cooling drum 10b. The first cooling drum 10a and the second cooling drum 10b have a concave profile in which the center in the axial direction is slightly depressed. Moreover, the 1st cooling drum 10a and the 2nd cooling drum 10b are comprised so that adjustment of the space | interval of cooling drum 10a, 10b is possible according to the plate | board thickness (internal quality) of the casting strip S to manufacture. The 1st cooling drum 10a and the 2nd cooling drum 10b are comprised so that a cooling medium (for example, cooling water) can distribute | circulate inside. The cooling drums 10a and 10b can be cooled by circulating the cooling medium inside the cooling drums 10a and 10b.

  In the present embodiment, the first cooling drum 10a and the second cooling drum 10b are set such that, for example, the outer diameter is 800 mm, the drum body length (width) is 1500 mm, and the plate crown of the casting strip S in a steady state is 30 μm (initial Processed). Needless to say, the outer diameter and drum length (width) of the pair of cooling drums 10a and 10b are not limited thereto.

  In the twin drum type continuous casting apparatus 10, as shown in FIG. 2, the dummy sheet 11 is connected to the tip of the casting strip S, and casting is started. A dummy bar 13 having a thickness larger than that of the cast strip S is provided at the tip of the dummy sheet 11, and the dummy sheet 11 is guided by the dummy bar 13. In addition, a protrusion 12 that is thicker than the thickness of the casting strip S is formed at the connection between the tip of the casting strip S and the dummy sheet 11. Rolling (flying touch) in the in-line mill 50 is started after the protrusion 12 has passed through the in-line mill 50.

  The antioxidant 20 is a device for performing a process for preventing the surface of the casting strip S immediately after casting from oxidizing and generating scale. In the antioxidant device 20, for example, the amount of oxygen can be adjusted by nitrogen gas. It is preferable to apply the antioxidant 20 as necessary in consideration of the steel type of the cast strip S to be cast.

  The cooling device 30 is a device that cools the cast strip S whose surface has been subjected to an antioxidant treatment by the antioxidant device 20. The cooling device 30 includes, for example, a plurality of spray nozzles (not shown), and ejects cooling water from the spray nozzles to the surface (upper surface and lower surface) of the casting strip S according to the steel type. Cooling.

  A pair of feed rolls 81 may be arranged between the antioxidant device 20 and the cooling device 30. The pair of feed rolls 81 sandwich the cast strip S by a reduction device (not shown) and measure the loop length of the cast strip S between the pair of cooling drums 10a and 10b and the feed roll 81, A horizontal conveying force is applied to the casting strip S so that the loop length is constant. The feed roll 81 is constituted by a pair of rolls having a roll diameter of 200 mm and a roll trunk length (width) of 2000 mm, for example.

  The first pinch roll device 40 is a pinch roll device arranged on the entry side of the inline mill 50. The first pinch roll device 40 includes an upper pinch roll and a lower pinch roll, a rolling load detection device, and a reduction device. Each of the upper pinch roll and the lower pinch roll has a hollow channel formed therein, and is configured to allow a cooling medium (for example, cooling water) to flow therethrough. The pinch roll can be cooled by circulating the cooling medium. For example, the upper pinch roll and the lower pinch roll may have a roll diameter of 400 mm and a roll body length (width) of 2000 mm. Further, the upper pinch roll and the lower pinch roll are arranged via a roll chock in the housing, and are rotationally driven by a motor (not shown).

  The tension generated between the first pinch roll device 40 and an in-line mill 50 to be described later can be measured by a tension roll 82 disposed therebetween. And speed control of a pair of pinch roll is performed so that the tension | tensile_strength which arises between the 1st pinch roll apparatus 40 and the in-line mill 50 may become preset tension.

  The in-line mill 50 is a rolling device that rolls the cast strip S so that the cast strip S has a desired thickness. In this embodiment, the in-line mill 50 is a two-high rolling mill having a pair of work rolls 51a and 51b. The in-line mill 50 includes an in-line mill control device (reference numeral 90 in FIG. 3) for controlling the in-line mill, a thickness gauge, and the like. The work rolls 51a and 51b are rotationally driven by a motor (not shown) and are cooled by cooling water from the entry side and the exit side. A hydraulic cylinder 55 is provided above the work roll 51a to press the work roll 51a down to the lower work roll 51b.

  As shown in FIG. 2, the in-line mill 50 has a roll gap while rotating the work rolls 51a and 51b of the in-line mill 50 after the tip of the casting strip S cast at the time of steady casting passes through the in-line mill 50. Tightening is started to start rolling. Such a rolling method is called a flying touch.

  As shown in FIG. 3, the in-line mill control device 90 includes a mill control unit 91 that controls the in-line mill 50, a hydraulic cylinder control unit 93 that controls the hydraulic cylinder 55, a roll shift control unit 95, a roll A rotation control unit 97.

  The hydraulic cylinder control unit 93 controls the hydraulic cylinder 55 connected to the work rolls 51a and 51b. The hydraulic cylinder control unit 93 controls the hydraulic cylinder 55 based on an instruction from the mill control unit 91 that controls the inline mill 50 so as to adjust the roll gap between the work rolls 51a and 51b. At this time, the mill control unit 91 forms the casting strip S at a preset thickness based on the thickness of the casting strip S measured by the thickness gauge 73 installed on the exit side of the in-line mill 50. Adjust the roll gap so that As the thickness gauge 73, for example, an X-ray thickness gauge or the like may be used. The roll shift control unit 95 moves the work rolls 51 a and 51 b in the roll axis direction based on instructions from the mill control unit 91. The roll rotation control unit 97 controls the rotation speed of the work rolls 51 a and 51 b based on an instruction from the mill control unit 91.

  The inline mill control device 90 may further include a roll bending setting unit (not shown) that sets the roll bending force. However, it goes without saying that the effect of roll bending on the plate shape (plate crown) is much greater in the case of the four-high rolling mill than in the case of the two-high rolling mill. Furthermore, position detection devices 71 and 72 that detect the position in the width direction of the casting strip S may be provided on at least one of the entry side and the exit side with respect to the inline mill 50. In FIG. 1, the position detection devices 71 and 72 are arranged on the entry side and the exit side of the inline mill 50, but as shown in FIG. 3, the position detection device 72 is provided only on the exit side of the inline mill 50. May be provided. For example, in order to detect the meandering amount of the casting strip S, the center position in the width direction of the casting strip S may be detected using the position detection devices 71 and 72. Detection values of the position detection devices 71 and 72 are output to the mill control unit 91 and used for controlling the in-line mill 50.

  Further, the work rolls 51a and 51b according to the present embodiment stably suppress the meandering of the casting strip S in the in-line mill 50 when rolling the casting strip S cast by the twin drum type continuous casting apparatus 10. A predetermined roll profile is set for rolling. And the roll gap of the work rolls 51a and 51b which contact | connects the casting strip S is changed by moving the said work roll to a roll axial direction corresponding to the plate profile of the casting strip S which changes with the elapsed time after casting start. Let The roll profile and roll shift of the work rolls 51a and 51b of the in-line mill 50 will be described later.

  Returning to the description of FIG. 1, the second pinch roll device 60 is disposed on the exit side of the inline mill 50. Similar to the first pinch roll device 40, the second pinch roll device 60 includes an upper pinch roll and a lower pinch roll, a rolling load detection device, and a reduction device. Each of the upper pinch roll and the lower pinch roll has a hollow channel formed therein, and is configured to allow a cooling medium (for example, cooling water) to flow therethrough. The pinch roll can be cooled by circulating the cooling medium. For example, the upper pinch roll and the lower pinch roll may have a roll diameter of 400 mm and a roll body length (width) of 2000 mm. Further, the upper pinch roll and the lower pinch roll are arranged via a roll chock in the housing, and are rotationally driven by a motor (not shown). A tension roll 83 is disposed between the inline mill 50 and the second pinch roll device 60.

  The winding device 70 is a device that is disposed on the exit side of the second pinch roll device 60 and winds the cast strip S into a coil shape. A deflector roll 84 is disposed between the second pinch roll device 60 and the winding device 70.

[1-2. Inline mill work roll]
In order for the work rolls 51a and 51b of the in-line mill 50 according to the present embodiment to stably roll while suppressing the meandering of the casting strip S, a predetermined roll profile is set. Then, the work rolls 51a and 51b are moved in the roll axis direction in accordance with the plate profile of the casting strip S that changes with the elapsed time after the start of casting, and the rolls of the work rolls 51a and 51b at the portions in contact with the casting strip S are moved. Roll while changing the gap. Hereinafter, based on FIG.4 and FIG.5, the roll profile of the work rolls 51a and 51b of the in-line mill 50 which concerns on this embodiment, and the effect | action by this are demonstrated. In addition, FIG. 4 is explanatory drawing which shows the shape of the work rolls 51a and 51b of the in-line mill 50 which concerns on this embodiment. FIG. 5 is an explanatory diagram illustrating a rolling process of the cast strip S by the work rolls 51a and 51b of the inline mill 50 according to the present embodiment.

(1) Roll profile Work roll 51a, 51b which concerns on this embodiment is a roll which has the same roll profile, and is arrange | positioned with a roll axis | shaft parallel. As shown in FIG. 4, the work rolls 51 a and 51 b are on one end side in the roll axis direction and have a diameter-enlarged portion C <b> 1 that expands from one end in the roll axis direction toward the other end side. A diameter-reduced portion C3 that is on the end side and is reduced in diameter from one end side to the other end in the roll axis direction, and between the enlarged-diameter portion C1 and the reduced-diameter portion C3 and from the enlarged-diameter portion C1 side to the reduced-diameter portion C3 side It consists of the intermediate part C2 which is diameter-expanded and then diameter-expanded. The enlarged diameter part C1, the intermediate part C2, and the reduced diameter part C3 have a continuous outer peripheral surface and form one roll. The roll diameters of the work rolls 51a and 51b are maximized at the boundary portion P1 between the enlarged diameter portion C1 and the intermediate portion C2, and are minimized at a predetermined position P2 between the intermediate portions C2, and the intermediate portion C2 and the reduced diameter portion. It becomes maximum at the boundary portion P3 with C3.

  As shown in FIG. 4, the work rolls 51 a and 51 b having such a roll profile are curved surfaces whose outer peripheral surfaces are undulated along the roll axis direction. The work rolls 51a and 51b are arranged so that the roll axes are parallel and point-symmetric. Then, according to the plate profile of the cast strip S to be rolled, the work rolls 51a and 51b are shifted in the roll axis direction so that the surface in contact with the cast strip S is changed, and the relative position is changed.

(2) Roll Shift Position FIG. 5 shows the roll shift positions of the work rolls 51a and 51b of the inline mill 50 according to the present embodiment and the plate profile (exit side plate profile) of the cast strip S rolled at the roll shift position. Show. In addition, the outgoing side plate profile is simplified and shown symmetrically.

  First, the roll shift position shown in the state A of FIG. 5 is a state in which the cast strip S is rolled at the enlarged diameter portion C1 and the intermediate portion C2 of the work rolls 51a and 51b (first stage). In the state A, one end side in the plate width direction of the casting strip S is in contact with the outer peripheral surface of the enlarged diameter portion C1 of the work roll 51a and the intermediate portion C2 of the work roll 51b, and the other end side is the intermediate portion C2 of the work roll 51a. Are in contact with the outer peripheral surface of the workpiece and the enlarged diameter portion C1 of the work roll 51b. The distribution between the roll gaps (exit side plate profile) at this time is a combination of a large convex crown and a large edge up. Therefore, the shape is suitable for rolling the casting strip S immediately after the start of casting as shown in the state A of FIG.

  Next, the roll shift position shown in the state B of FIG. 5 is roll-shifted so that the end portions of the work rolls 51a and 51b on the side of the enlarged diameter portion C1 are away from the roll shift position of the state A, and the cast strip S is enlarged. In this state, the range in contact with C1 is reduced. The distribution between the roll gaps at this time (exit side plate profile) is a combination of a small convex crown and a small edge up. Therefore, it has a shape suitable for rolling of the casting strip S after a while has passed since the start of casting as shown in the state B of FIG.

  And the roll shift position shown in the state C of FIG. 5 is roll-shifted so that the diameter-enlarged part C1 side edge part of each work roll 51a, 51b is further away from the roll shift position of the state B, and the work rolls 51a, 51b The cast strip S is rolled at a portion closer to the reduced diameter portion C3 than the minimal portion P2 in the intermediate portion C2 (third stage). That is, the casting strip S is rolled at a portion where the outer peripheral surfaces facing each other at the intermediate portion C2 of the work rolls 51a and 51b are substantially parallel. At this time, the distribution between the roll gaps (exit side plate profile) is substantially rectangular, and has a shape suitable for rolling the casting strip S in a steady state as shown in the state C of FIG.

  Thus, by changing the relative position in the roll axis direction of the work rolls 51a and 51b having the above-mentioned roll profile, the plate thickness between the width direction center and both ends as shown in the states A and B of FIG. It is possible to control the plate crown of the cast strip S with a thickened plate profile.

  Further, the work rolls 51a and 51b according to the present embodiment are further provided with a reduced diameter portion C3, so that, for example, a concave exit side plate profile in which a central portion in the plate width direction is depressed as shown in the state D of FIG. Even in this case, the shape can be corrected. For example, the initial profile of the cooling drums 10a and 10b may be too large, or the influence of disturbance such as insufficient cooling of the cooling drums 10a and 10b may cause the plate profile in the steady state to have a concave shape. . In this case, as shown in the state D in FIG. 5, the roll shift is performed so that the end portions on the diameter-enlarged portion C1 side of the work rolls 51a and 51b are further away from the roll shift position in the state C. The cast strip S may be rolled by a portion of the portion C2 closer to the reduced diameter portion C3 than the minimal portion P2 and the reduced diameter portion C3 (fourth stage).

  As described above, the position detection devices 71 and 72 for detecting the position of the casting strip S in the plate width direction are arranged on the entry side and the exit side of the in-line mill 50 as shown in FIG. Good. Thereby, based on the detection results of the position detection devices 71 and 72, it is possible to detect that the center position of the casting strip S in the plate width direction has shifted, and when the center position shifts (that is, off-center). In this case, the positions of the work rolls 51a and 51b are shifted and corrected asymmetrically so as to be appropriately arranged with respect to the casting strip S.

  Thus, the roll profile of the work rolls 51a and 51b of the in-line mill 50 according to the present embodiment is set as described above, and the work roll 51a against the crown change of the casting strip S from the start of casting to the steady state. , 51b is shifted in the roll axis direction, and the crown change ratio during rolling can be suppressed. Therefore, the shape fluctuation at the time of rolling can be suppressed, plate breakage due to meandering and drawing of the casting strip S in the in-line mill 50 can be prevented, and the timing of the flying touch can be further advanced.

[1-3. Casting strip production]
Hereinafter, the manufacture of the cast strip S in the cast strip manufacturing process 1 shown in FIG. 1 will be described.

  First, the molten metal is temporarily stored in the tundish T. The molten metal stored in the tundish T is injected into the molten metal storage portion 15 of the twin-drum continuous casting apparatus 10 through a nozzle formed in the lower part of the tundish. At this time, the amount of the molten metal stored in the molten metal storage unit 15 is controlled to be constant by controlling the nozzle.

  Next, while rotating the pair of cooling drums 10a and 10b, the molten metal stored in the molten metal storage unit 15 is solidified and grown on the peripheral surfaces of the pair of cooling drums 10a and 10b, thereby casting the casting strip S. When casting is started in the twin-drum type continuous casting apparatus 10, for example, as shown in FIG. 2, the dummy sheet 11 is connected to a portion that becomes the tip of the casting strip S. At this time, a dummy bar 13 that is much thicker than the casting strip S is provided at the leading end side in the traveling direction of the dummy sheet 11, and the connecting portion between the casting strip S and the dummy sheet 11 is larger than the thickness of the casting strip S. A thick protrusion 12 is formed. For example, the dimensions of the cast strip S may be 2 mm in thickness and 1200 mm in width, and the peripheral speed (casting speed) of the pair of cooling drums 10a and 10b may be 150 m / min. However, the dimensions of the casting strip S and the casting speed are not limited to this example.

  The casting strip S formed by the pair of cooling drums 10a and 10b is subjected to an antioxidant treatment in the antioxidant device 20 as necessary. And the casting strip S is conveyed downstream by the feed roll 81, keeping the loop length of the casting strip S between the cooling drums 10a, 10b and the feed roll 81 constant. Moreover, the casting strip S is cooled with the cooling device 30 as needed. Thereafter, the cast strip S is fed to the in-line mill 50 while tension is generated between the first pinch roll device 40 and the in-line mill 50 by the first pinch roll device 40.

  Next, the inline mill 50 starts a flying touch after the protrusion 12 has passed through the inline mill 50. That is, the rolling force is applied while synchronizing the roll speed of the in-line mill 50 with the plate speed of the casting strip S. The in-line mill 50 rolls the cast strip S and adjusts it to a desired plate thickness. Here, the roll shift amounts of the work rolls 51a and 51b in the in-line mill 50 may be calculated in advance by experiments. That is, the roll shift amount of the work rolls 51a and 51b is controlled according to the plate profile of the cast strip from the start of casting to the steady state. When the casting strip S is off-center, the detected position information of the casting strip is sent to the mill control unit 91, and the mill control unit 91 calculates the plate width center position of the slab. The roll shift amount is corrected.

  The casting strip S rolled by the in-line mill 50 is wound by the second pinch roll device 60 while a tension is generated between the in-line mill 50 and the second pinch roll device 60 by the second pinch roll device 60. It is conveyed to. The winding device 70 winds up the cast strip S that has been conveyed.

  In the above, the rolling equipment which rolls the slab cast by the twin drum type continuous casting apparatus which concerns on 1st Embodiment with a pair of work roll, and the rolling method by this were demonstrated.

<2. Second Embodiment>
Next, based on FIG.6 and FIG.7, the rolling equipment which rolls the slab cast by the twin drum type continuous casting apparatus which concerns on the 2nd Embodiment of this invention with a pair of work roll, and the rolling method by this Will be described. FIG. 6 is an explanatory diagram illustrating a configuration of an inline mill control device 90 that controls the inline mill 50 according to the present embodiment. FIG. 7 is an explanatory view showing the work rolls 51a and 51b and the backup rolls 53a and 53b constituting the inline mill 50. FIG. The casting strip manufacturing process according to this embodiment is basically the same as that of the first embodiment, and only the configuration of the inline mill 50 is different as shown in FIG.

  That is, the in-line mill 50 according to the first embodiment is a two-high mill, but the in-line mill 50 according to the present embodiment is a four-high mill having a pair of backup rolls 53a and 53b. If the steel type and product width of the casting strip S are the same, it can be handled by the rolling mill having the configuration according to the first embodiment. However, when the steel type changes, the rolling force of the in-line mill 50 changes. At this time, since the deflection of the work rolls 51a and 51b also changes, it is difficult to cope with all the steel types with only one roll profile of the work rolls 51a and 51b (that is, to make the crown complement change uniform).

  In this case, it is necessary to replace the work roll for each steel type and sheet width. Further, since the maximum load of the bearing portion is determined by the roll diameter, it is necessary to increase the roll diameter when the load in the in-line mill 50 is large. As a result, the contact arc length also increases, so the in-line mill 50 is enlarged. May end up. Therefore, by adopting the configuration of the inline mill 50 according to the present embodiment, it is possible to easily cope with such a case.

  That is, as shown in FIG. 6, backup rolls 53a and 53b that support the work rolls 51a and 51b of the in-line mill 50 shown in FIG. 3 are arranged so that the rolling load is received by the backup rolls 53a and 53b. The roll diameters of the backup rolls 53a and 53b may be the same in the roll axis direction. The work rolls 51a and 51b are roll-shifted, but the positions of the backup rolls 53a and 53b in the roll axis direction may be fixed.

  However, if the length of the backup rolls 53a and 53b is the same as the length of the work rolls 51a and 51b, the load distribution between the work rolls 51a and 51b and the backup rolls 53a and 53b is affected by the load distribution between the work rolls 51a and 51b. This gap does not become the outgoing plate profile as shown in FIG. 5, but induces a composite wave and causes the plate to break.

  Therefore, in the in-line mill 50 according to the present embodiment, the cylinder lengths of the backup rolls 53a and 53b are made shorter than the plate width W of the casting profile S as shown in FIG. Thereby, the influence of compound elongation can be prevented. The body lengths of the backup rolls 53a and 53b are preferably shorter than the plate width W of the casting profile S by about 50 mm to 100 mm. As a result, the roll mark is transferred to the thin piece after rolling, but there is no problem because it is rendered harmless by pickling in the subsequent step.

  Examples of the present invention will be described below. Example 1 was implemented in the manufacturing process of the cast strip provided with the structure similar to FIG. The cast strip used in Example 1 had a plate thickness of 2 mm and a plate width of 1200 mm. The acceleration rate of the cooling drum from the start of casting was 150 m / min / 30 seconds, and the rotation speed of the cooling drum in the steady casting state was 150 m / min. The reduction ratio in the inline mill was 30%, and the thickness of the cast strip on the outlet side of the inline mill was 1.4 mm. Further, the tension between the first pinch roll device and the in-line mill was 3.6 tf (stress: about 15 MPa) as a resultant force. Moreover, the pressing force was about 15 tf in total on the left and right.

  On the other hand, as Comparative Examples 1 and 2, the case where a two-high rolling mill was used in an in-line mill according to the prior art was verified. In Comparative Example 1, the roll diameter of the work roll of the in-line mill was constant (flat). In Comparative Example 2, the work roll of the in-line mill was an S-shaped roll profile.

  First, in Comparative Example 1, a stable flying touch could not be achieved even after 28 seconds from the start of casting. As a result, an off gauge of about 40 m was generated. In Comparative Example 2, a stable flying touch was possible in 22 seconds from the start of casting, and the off gauge was shorter than Comparative Example 1 and was suppressed to about 31 m. However, before 22 seconds from the start of casting, rolling corresponding to the edge-up was not properly performed, and plate breakage occurred frequently.

  On the other hand, in Example 1, a stable flying touch became possible in 8 seconds from the start of casting, and the off gauge was suppressed to about 12 m. As Example 2, the configuration of the in-line mill was verified using a four-high rolling mill provided with a backup roll shown in FIG. At this time, the roll profile of the work roll and other rolling conditions were the same as those in Example 1. In Example 2, the casting strip was manufactured for a plurality of steel types. Even when the deformation resistance doubled due to the difference in the steel types, the flying touch was stable in the elapsed time from the start of casting as in Example 1. And off-gauge was reduced to the same extent. In Example 2 (when the deformation resistance is twice), when the rolling mill of Example 1 is used, a desired rolling reduction can be obtained due to the pressing force limit of the rolling mill (due to bearing strength). There wasn't.

  Further, as Example 3, the case where a position detection device (position detection device 75 in FIG. 3) for detecting the position in the sheet width direction of the slab was installed on the delivery side of the rolling mill was verified. In the third embodiment, the position information detected by the position detection device is transmitted to the mill control unit, and the plate width center position of the slab is calculated by the mill control unit. Based on the result and the time change of the plate profile of the slab cast by the twin drum type continuous casting apparatus acquired in advance, the roll shift control unit sandwiches the slab symmetrically with respect to the center position in the plate width direction. In addition, the relative position of each work roll in the roll axis direction is controlled. At that time, the casting strip was intentionally off-centered by 50 mm on the entrance side of the rolling mill. In contrast to Example 3, in Comparative Example 3, the casting strip was intentionally off-centered 50 mm on the rolling mill entrance side, but the same operation as Example 1 was performed without considering the effect of off-center. .

  As a result of performing Example 3 and Comparative Example 3, in Example 3, as in Example 2, stable flying touch was possible in 8 seconds from the start of casting, and the off gauge was suppressed to about 12 m. On the other hand, in Comparative Example 3, rolling corresponding to edge-up was not performed properly, and plate breakage occurred frequently.

  From the above, according to the present invention, it is possible to prevent meandering of the casting strip in the in-line mill which is a rolling equipment in the twin drum type continuous casting equipment, and the flying touch can be performed at an early stage. It was found that it can be manufactured stably. As a result, it has become clear that the manufacturing cost of the cast strip can be reduced.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Twin drum type continuous casting apparatus 10a, 10b Cooling drum 11 Dummy sheet 12 Protrusion part 13 Dummy bar 15 Metal molten metal storage part 20 Antioxidation apparatus 30 Cooling apparatus 40 1st pinch roll apparatus 50 Inline mill 51a, 51b Work roll 53a, 53b Backup roll 60 Second pinch roll device 70 Winding device 71, 72 Position detection device 73 Plate thickness meter 81 Feed roll 82, 83 Tension roll 84 Deflector roll 90 Inline mill control device 91 Mill control unit 93 Hydraulic cylinder control unit 95 Roll Shift control unit 97 Roll rotation control unit S Casting strip (thin-walled slab)
T tundish C1 expanded diameter part C2 intermediate part C3 reduced diameter part

Claims (8)

A rolling facility for rolling a slab cast by a twin drum type continuous casting apparatus with a pair of work rolls,
Each said work roll is
A diameter-expanding portion that is located on one end side in the roll axis direction and that increases in diameter from one end in the roll axis direction toward the other end side, and on the other end side in the roll axis direction and from the one end side in the roll axis direction. A diameter-reduced portion that is diameter-reduced toward an end, an intermediate portion that is between the diameter-expanded portion and the diameter-reduced portion and is diameter-reduced from the diameter-expanded portion side toward the diameter-reduced portion side, and Consists of
The roll diameter has a roll profile that is maximal at the boundary between the enlarged diameter part and the intermediate part, is minimal at the intermediate part, and is maximal at the boundary part between the intermediate part and the reduced diameter part,
Rolling equipment arranged symmetrically with respect to a point and capable of relative movement in the roll axis direction. A pair of backup rolls supporting the pair of work rolls;
The rolling equipment according to claim 1, wherein a body length of the backup roll is shorter than a plate width of the slab being rolled by a pair of the work rolls.   A roll shift control unit that controls a relative position of each work roll in a roll axis direction based on a time change of a plate profile of the slab cast by the twin drum type continuous casting apparatus acquired in advance; Item 3. The rolling equipment according to item 1 or 2. At least one of the rolling direction entry side and the exit side of the rolling equipment includes a position detection device that detects a plate width direction position of the slab,
Based on the position in the plate width direction of the slab detected by the position detection device, the relative position of each work roll in the roll axis direction is set so as to be sandwiched symmetrically with respect to the center position in the plate width direction. The rolling equipment of Claim 3 provided with the roll shift control part to control. A rolling method in which a slab cast by a twin drum type continuous casting apparatus is rolled by a rolling facility provided with a pair of work rolls,
Each said work roll is
A diameter-expanding portion that is located on one end side in the roll axis direction and that increases in diameter from one end in the roll axis direction toward the other end side, and on the other end side in the roll axis direction and from the one end side in the roll axis direction. A diameter-reduced portion that is diameter-reduced toward an end, an intermediate portion that is between the diameter-expanded portion and the diameter-reduced portion and is diameter-reduced from the diameter-expanded portion side toward the diameter-reduced portion side; Consists of
The roll diameter has a roll profile that is maximal at the boundary between the enlarged diameter part and the intermediate part, is minimal at the intermediate part, and is maximal at the boundary part between the intermediate part and the reduced diameter part,
It is arranged so as to be point-symmetric and relatively movable in the roll axis direction,
Before the start of rolling the slab, calculate the time change of the plate profile of the slab cast by the twin drum continuous casting device,
A rolling method of rolling the slab by moving the work roll relative to the roll axis direction based on a change in the plate profile of the slab calculated in advance. Based on the time change of the plate profile of the slab acquired in advance, the work roll is relatively moved in the roll axis direction,
A plate width direction position of the slab is detected by a position detection device arranged on at least one of the rolling direction entry side and the exit side of the rolling equipment, and the slab plate detected by the position detection device The rolling method according to claim 5, wherein the relative position in the roll axis direction of each work roll is controlled based on the position in the width direction so that the slab is sandwiched symmetrically with respect to the center position in the sheet width direction. Rolling based on the plate profile of the slab,
A first stage of rolling the slab at the enlarged diameter part and the intermediate part of each work roll;
A second stage of rolling the slab at the intermediate portion so as to include a minimal portion having a minimum roll diameter at the intermediate portion of each work roll;
A third step of rolling the slab at a portion closer to the reduced diameter portion than the minimal portion of the intermediate portion of each work roll;
The rolling method according to claim 5 or 6, comprising: The method further comprises a fourth step of rolling the slab after the third step by using the portion on the reduced diameter side of the minimum portion and the reduced diameter portion of the intermediate portion of each work roll. Item 8. The rolling method according to Item 7.

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