Patent Description:
A reverse-type rolling apparatus is known, which is configured to reciprocate and roll a metal plate passed between a pair of mill rolls.

Patent Document <NUM> discloses a reverse-type rolling apparatus which includes a rolling stand with a mill roll, and two reels (an unwinder and a winder) disposed in front and behind the rolling stand. In this rolling apparatus, in a process of rolling in the rolling stand a rolled material unwound from the first reel and winding the rolled material with the second reel (rolling pass), the rolling apparatus is stopped once a tail end of the rolled material separating from the first reel reaches an exit side of the rolling stand and rolling in a next pass (a process of rolling in the rolling stand the rolled material unwound from the second reel and winding the rolled material with the first reel) is started.

<CIT> discloses a control device for controlling a rolling apparatus with the features in the preamble of present claim <NUM>. Other conventional control devices are described in <CIT> and <CIT>.

As in the reverse-type rolling apparatus described in Patent Document <NUM>, by continuing rolling even after the tail end of a strip (rolled material) separates from the unwinder, yield can be improved compared to a case where rolling is performed while maintaining a state where a tail end portion of the strip is gripped by the unwinder. Meanwhile, time is required to accurately stop the tail end of the strip unwound from the unwinder at a position suitable for the start of rolling in the next pass. Further, after the tail end of the strip is stopped, at the start of rolling in the next pass, it is difficult to smoothly pass a head end of the strip (a tail end in a previous pass) through a deflector roll, etc. disposed between the unwinder and the mill roll, which may result in a loss of time.

In view of the above, an object of at least one embodiment of the present invention is to provide a control device for a rolling apparatus, a rolling facility, and a control method for the rolling apparatus, which are capable of improving yield while suppressing an increase in time required for rolling.

A control device for a rolling apparatus according to at least one embodiment of the present invention is a control device for controlling a rolling apparatus including a pair of mill rolls for rolling a metal strip, an unwinder for unwinding the strip toward the pair of mill rolls, and a winder for winding the strip rolled by the pair of mill rolls, including: a rotation control unit for controlling rotation of the mill rolls; a velocity acquisition unit configured to acquire velocity of the strip between the unwinder and the mill rolls; and a separation detection unit configured to detect separation of a tail end of the strip from the unwinder. The rotation control unit is configured to stop the rotation of the pair of mill rolls, based on a separation timing which is a timing when the separation of the tail end from the unwinder is detected by the separation detection unit and the velocity of the strip acquired by the velocity acquisition unit.

Further, a rolling facility according to at least one embodiment of the present invention, includes: a rolling apparatus including a pair of mill rolls for rolling a metal strip, an unwinder for unwinding the strip toward the pair of mill rolls, and a winder for winding the strip rolled by the pair of mill rolls; and the above-described control device for controlling the rolling apparatus.

A control method for a rolling apparatus according to at least one embodiment of the present invention is a control method for controlling a rolling apparatus including a pair of mill rolls for rolling a metal strip, an unwinder for unwinding the strip toward the pair of mill rolls, and a winder for winding the strip rolled by the pair of mill rolls, including: a rotation control step of controlling rotation of the mill rolls; a velocity acquisition step of acquiring velocity of the strip between the unwinder and the mill rolls; and a separation detection step of detecting separation of a tail end of the strip from the unwinder. The rotation control step includes stopping the rotation of the pair of mill rolls, based on a separation timing which is a timing when the separation of the tail end from the unwinder is detected in the separation detection step and the velocity of the strip acquired in the velocity acquisition step.

According to at least one embodiment of the present invention, provided are a control device for a rolling apparatus, a rolling facility, and a control method for the rolling apparatus, which are capable of improving yield while suppressing an increase in time required for rolling.

Some embodiments of the present invention will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described or shown in the drawings as the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.

<FIG> is a schematic configuration view of a rolling facility to which a control device is applied according to an embodiment. As shown in <FIG>, a rolling facility <NUM> includes a rolling apparatus <NUM> for rolling a metal strip S (such as a strip-shaped steel strip), and a control device <NUM> for controlling the rolling apparatus <NUM>.

The rolling apparatus <NUM> includes a rolling mill <NUM> for rolling the strip S, an unwinder <NUM> disposed at an entry side of the rolling mill <NUM> (that is, an upstream side of the rolling mill <NUM> in a traveling direction of the strip S being rolled), and a winder <NUM> disposed at an exit side of the rolling mill <NUM> (that is, a downstream side of the rolling mill <NUM> in the traveling direction of the strip S being rolled). The rolling apparatus <NUM> may include, for example, one rolling mill <NUM> as shown in <FIG>, or may include not less than two rolling mills <NUM>.

The rolling mill <NUM> includes a pair of mill rolls (work rolls) <NUM>, <NUM> disposed on both surface sides of the strip S with the strip S interposed therebetween. As shown in <FIG>, the rolling mill <NUM> may include a pair of intermediate rolls <NUM>, <NUM> and a pair of backup rolls <NUM>, <NUM> each disposed opposite to the strip S across the pair of mill rolls <NUM>, <NUM>, respectively. The intermediate rolls <NUM>, <NUM> and the backup rolls <NUM>, <NUM> are configured to support the mill rolls <NUM>, <NUM>. Further, the rolling mill <NUM> includes a rolling-reduction device (such as a hydraulic cylinder; not shown) for performing rolling-reduction on the strip S between the pair of mill rolls <NUM>, <NUM> by applying a load to the pair of mill rolls <NUM>, <NUM>.

The mill rolls <NUM>, <NUM> are connected to a motor <NUM> via a spindle (not shown), etc., and the mill rolls <NUM>, <NUM> are rotationally driven by the motor. In rolling of the strip S, a friction force is generated between the strip s and the mill rolls <NUM>, <NUM> by rotating the mill rolls <NUM>, <NUM> with the motor <NUM> while the rolling-reduction device performs rolling-reduction on the strip S. With the friction force, the strip S is sent to the exit side of the mill rolls <NUM>, <NUM>.

The unwinder <NUM> is configured to unwind a coil of the strip S toward the rolling mill <NUM>. The unwinder <NUM> includes a mandrel <NUM>, and is configured to unwind the strip S toward the rolling mill <NUM> by rotationally driving the mandrel <NUM> with a motor (not shown). The mandrel <NUM> of the unwinder <NUM> is driven by the motor (not shown) to apply an entry-side tension to the strip S, in rolling of the strip S.

The winder <NUM> is configured to wind the strip S from the rolling mill <NUM>. The winder <NUM> includes a mandrel <NUM>, and is configured to wind the strip S by rotationally driving the mandrel <NUM> with a motor (not shown). When the strip S is rolled while being wound by the mandrel <NUM> of the winder <NUM>, an exit-side tension is applied to the strip S by the mandrel <NUM> of the winder <NUM>.

As shown in <FIG>, a guide part <NUM> for guiding the strip S introduced from the mandrel <NUM> of the unwinder <NUM> to the rolling mill <NUM> may be disposed between the rolling mill <NUM> and the mandrel <NUM> of the unwinder <NUM>. A guide part <NUM> for guiding the strip S sent from the rolling mill <NUM> to the mandrel <NUM> of the winder <NUM> may be disposed between the rolling mill <NUM> and the mandrel <NUM> of the winder <NUM> The guide parts <NUM>, <NUM> may include deflector rolls <NUM>, <NUM> and/or guide tables <NUM>, <NUM>.

In some embodiments, the rolling apparatus <NUM> is a reverse-type rolling apparatus (reverse mill) which is configured to reciprocate and roll the strip S passed between the pair of mill rolls <NUM>, <NUM>. In the reverse-type rolling apparatus <NUM>, rolling is stopped immediately before a tail end St of the strip S unwound from the mandrel <NUM> of the unwinder <NUM>, and rolling in an odd-number pass (first pass, etc.) is completed in a state where the strip S is subjected to rolling-reduction on the mill rolls <NUM>, <NUM>. And then, the strip S is unwound from the mandrel <NUM> of the winder <NUM> toward the rolling mill <NUM>, and rolling in an even-number pass (second pass, etc.) is performed by moving the strip S in a traveling direction reverse to the preceding direction while winding the strip S by the mandrel <NUM> of the unwinder <NUM>. That is, the role of the unwinder <NUM> and the role of the winder <NUM> are interchanged, in accordance with the traveling direction of the strip S.

<FIG> is a partial cross-sectional view of the unwinder <NUM> (winder <NUM>) according to an embodiment and a view for describing an operation of the unwinder <NUM> (winder <NUM>). As shown in <FIG> and <FIG>, the unwinder <NUM> includes a gripper <NUM> for gripping a tail end portion Sa including the tail end St of the strip S. Further, the winder <NUM> includes a gripper <NUM> for gripping a head end portion including a head end of the strip S.

In the exemplary embodiment shown in <FIG>, the gripper <NUM>, <NUM> is disposed to be movable along the radial direction, between an outer peripheral surface of the mandrel <NUM>, <NUM> and a radially inner side of the mandrel <NUM>, <NUM>. The mandrel <NUM>, <NUM> is provided with a slot <NUM> which opens to a surface of the mandrel <NUM>, <NUM> and can receive the tail end or the head end of the strip S.

The tail end portion or the head end portion of the strip is gripped by moving the gripper <NUM>, <NUM> radially outward by an actuator (not shown), etc., and providing the strip S with a force from the gripper <NUM>, <NUM> toward the mandrel <NUM>, <NUM>. The gripping of the tail end portion or the head end portion of the strip S by the gripper <NUM>, <NUM> is released by moving the gripper <NUM>, <NUM> radially inward by an actuator, etc., and releasing a force acting on the strip S from the gripper <NUM>, <NUM>.

When the strip S is rolled with the rolling apparatus <NUM>, basically, the mill rolls <NUM>, <NUM>, and the mandrels <NUM> and <NUM> of the unwinder <NUM> and the winder <NUM> are rotated while applying tension to the strip S in a state where the grippers <NUM>, <NUM> grip the tail end portion and the head end portion of the strip S.

As shown in <FIG>, the rolling facility <NUM> may include a pressing part <NUM> for correcting a shape of the tail end portion Sa of the strip S. The more detailed configuration of the pressing part <NUM> will be described later.

As shown in <FIG>, the rolling facility <NUM> may include a velocity sensor <NUM> for detecting velocity of strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM>. The velocity sensor <NUM> is electrically connected to the control device <NUM>, and a signal indicating the velocity of the strip S detected by the velocity sensor <NUM> is sent to the control device <NUM>.

As shown in <FIG>, the rolling facility <NUM> may include a sensor <NUM> for detecting separation of the tail end St of the strip S from the unwinder <NUM>. The sensor <NUM> may be a sensor capable of detecting presence or absence of the strip S at a position above, below, or lateral to the unwinder <NUM>. The sensor <NUM> may be a distance meter (laser distance meter, etc.) capable of detecting a distance from the sensor <NUM> to the strip S. The sensor <NUM> is electrically connected to the control device <NUM>, and a signal indicating the detection result by the sensor <NUM> is sent to the control device <NUM>.

The sensor <NUM> shown in <FIG> is a sensor capable of detecting the presence or absence of the strip S at the position below the unwinder <NUM>. The sensor <NUM> shown in <FIG> is a distance sensor disposed at the position below the unwinder <NUM> and capable of detecting a distance between the sensor <NUM> and the strip S in the horizontal direction.

<FIG> is a schematic configuration diagram of the control device <NUM> according to an embodiment. As shown in <FIG>, the control device <NUM> includes a rotation control unit <NUM>, a velocity acquisition unit <NUM>, and a separation detection unit <NUM>. The control device <NUM> may further include a gripping control unit <NUM> and/or a pressing control unit <NUM>.

The rotation control unit <NUM> is configured to control rotation of the mill rolls <NUM>, <NUM>. More specifically, the rotation control unit <NUM> is configured to stop the mill rolls <NUM>, <NUM> based on a separation timing which is a timing when the separation of the tail end St of the strip S from the unwinder <NUM> is detected by the separation detection unit <NUM> (described later) and the velocity of the strip S acquired by the velocity acquisition unit <NUM> (described later). The rotation control unit <NUM> may be configured to stop the rotation of the mill rolls <NUM>, <NUM> based on, in addition to the separation timing and the velocity of the strip S which are described above, a length of the strip S from a position of the tail end St at the above-described separation timing to an estimated stop position of the tail end St.

The velocity acquisition unit <NUM> is configured to acquire the velocity of the strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM>. The velocity acquisition unit <NUM> may acquire the velocity of the strip S described above, based on the signal indicating the velocity of the strip S, which is received from the above-described velocity sensor <NUM>. Alternatively, the velocity acquisition unit <NUM> may acquire the velocity of the strip S by acquiring rotation speed of the mill rolls <NUM>, <NUM> or the motor <NUM> for driving the mill rolls15, <NUM> from a rotation speed sensor, etc., and estimating the velocity of the strip S from the rotation speed by using a backward slip, etc..

The separation detection unit <NUM> is configured to detect the separation of the tail end St of the strip S from the unwinder <NUM>. The separation detection unit <NUM> may be configured to detect the separation of the tail end St from the unwinder <NUM>, based on the signal from the sensor <NUM> capable of detecting the presence or absence of the strip S at the same position as the guide part <NUM> (the deflector roll <NUM>, the guide table <NUM>, or the like) or a position between the guide part <NUM> and the unwinder <NUM> in the traveling direction of the strip S (a direction from the unwinder <NUM> toward the winder <NUM>), and the position above, below, or lateral to the unwinder <NUM>.

The sensor <NUM> may be configured to detect the presence or absence of the strip S at the position below the unwinder <NUM> (see the sensor <NUM> of <FIG>, a sensor 42A of <FIG>). In this case, the separation detection unit <NUM> may be configured to determine, based on the signal from the sensor <NUM>, that the tail end St separates from the unwinder <NUM>, when the presence of the strip S is detected at the position below the unwinder <NUM>.

The sensor <NUM> of <FIG> and the sensor 42A of <FIG> are each a distance sensor disposed at the position below the unwinder <NUM> and capable of detecting a distance between the sensor <NUM>, 42A and the strip S in the horizontal direction.

Alternatively, the sensor <NUM> may be configured to detect the presence or absence of the strip S at the position above the unwinder (see a sensor 42B or 42C of <FIG>). In this case, the separation detection unit <NUM> may be configured to determine, based on the signal from the sensor <NUM>, that the tail end St separates from the unwinder <NUM>, when the absence of the strip S is detected at the position above the unwinder <NUM>.

The sensor 42B of <FIG> is a distance sensor disposed at the position above the unwinder <NUM> and capable of detecting a distance between the sensor 42B and the strip S in the horizontal direction. The sensor 42C of <FIG> is a distance sensor disposed at the position above the unwinder <NUM> and capable of detecting a distance between the sensor 42C and the strip S in the vertical direction.

<FIG> are each a view for describing a control flow of the rolling apparatus according to an embodiment. Although <FIG> show the three sensors 42A, 42B, 42C as the sensor <NUM>, it is possible to detect the separation of the tail end St of the strip S from the unwinder <NUM> as long as one sensor <NUM> (for example, any one of the sensors 42A to 42C in <FIG>) is provided.

The gripping control unit <NUM> is configured to control the operation of the gripper <NUM> (that is, the gripping of the tail end portion or the head end portion of the strip S by the gripper <NUM>, and/or releasing of the gripping). The gripping control unit <NUM> may be configured to release the gripping of the tail end portion Sa of the strip S by the gripper, based on the number of windings (turns) of the strip S in the unwinder <NUM>. The number of windings of strip S in the unwinder <NUM> may be calculated from the number of windings or the length of the strip S at the start of the rolling pass and/or an angular position of the gripper <NUM> around a rotational axis of the mandrel <NUM>, etc..

The pressing control unit <NUM> is configured to control the operation of the pressing part <NUM>. The more detailed configuration of the pressing control unit <NUM> will be described later.

The control device <NUM> includes a calculator with a processor (such as CPU), a main storage device (memory device; such as RAM), an auxiliary storage device, an interface, and the like. The control device <NUM> is configured to receive the signals from the velocity sensor <NUM> and/or the sensor <NUM> via the interface. The processor is configured to process the signals thus received. In addition, the processor is configured to process programs loaded into the main storage device. Whereby, the function of each of the functional units (the rotation control unit <NUM>, the velocity acquisition unit <NUM>, the separation detection unit <NUM>, and the like) described above is realized.

The processing contents in the control device <NUM> is implemented as programs executed by the processor. The programs may be stored in, for example, the auxiliary storage device. When executed, these programs are loaded into the main storage device. The processor is configured to read out the programs from the main storage device to execute instructions included in the programs.

Next, a control method for the rolling apparatus <NUM> according to some embodiments will be described with reference to <FIG>. Hereinafter, a case will be described where the above-described rolling apparatus <NUM> is controlled by using the above-described control device <NUM>. However, in some embodiments, the control method for the rolling apparatus may be performed by using another device, or part of a procedure described below may be performed manually.

<FIG> is a flowchart of the control method for the rolling apparatus according to an embodiment. <FIG> are each a view for describing the control flow of the rolling apparatus according to an embodiment, and a view showing a change over time of the position of the strip S in the control of the rolling apparatus.

As shown in <FIG>, in the control method according to an embodiment, the gripping control unit <NUM> releases the gripping of the tail end portion Sa of the strip S by the gripper <NUM> of the unwinder <NUM>, during rolling of the strip S in the rolling apparatus <NUM> (S2). Further, the velocity acquisition unit <NUM> acquires the velocity of the strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM> (S4). Furthermore, the separation detection unit <NUM> detects the separation of the tail end St of the strip S from the unwinder <NUM> (S6). Then, the rotation control unit <NUM> controls and stops the rotation of the mill rolls <NUM>, <NUM>, based on the velocity of the strip S acquired in step S4 and the timing (separation timing) when the separation of the tail end St from the unwinder <NUM> is detected in the step S6.

Step S2 includes appropriately operating the actuator for moving the gripper <NUM> of the unwinder <NUM> to release the gripping of the tail end portion Sa of the strip S by the gripper <NUM>, if the number of windings of the strip S in the unwinder <NUM> decreases, during rolling of the strip S in the rolling apparatus <NUM> (S2). Step S2 typically includes releasing the gripping of the tail end portion Sa by the gripper <NUM>, in a state where the strip S is wound on the mandrel <NUM> of the unwinder <NUM> at not less than one round.

Before the gripping of the tail end portion Sa of the strip S by the gripper <NUM> is released in step S2, the tail end and the tail end portion of the strip S are unseparated from the mandrel <NUM> as shown in <FIG>. If the gripping of the tail end portion Sa of the strip S by the gripper <NUM> is released in step S2, the tail end St and the tail end portion Sa of the strip S separate from the mandrel <NUM> (unwinder <NUM>) as shown in <FIG>. Then, as time passes, positions of the strip S and the tail end St change as shown in <FIG> and further as shown in <FIG>.

Step S4 includes acquiring the velocity of the strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM>. Step S4 may include acquiring the velocity of the strip S described above, before a point in time when the gripping of the tail end portion Sa by the gripper <NUM> is released in step S2, or may include acquiring the velocity of the strip S described above, after the point in time. Further, the velocity of the strip S described above may be acquired until the mill rolls <NUM>, <NUM> are stopped in subsequent step S8. Step S4 may include acquiring the velocity of the strip S described above, continuously or every predetermined period.

Step S6 includes detecting the separation of the tail end St from the unwinder <NUM>, based on the signal from the sensor <NUM> capable of detecting the presence or absence of the strip at the position above or below the mandrel <NUM> of the unwinder <NUM>.

In an embodiment, whether the tail end St of the strip S separates from the unwinder <NUM> is determined by using the detection signal of the sensor 42A (see <FIG>) configured to detect the presence or absence of the strip at the position below the mandrel <NUM> of the unwinder <NUM>.

Herein, <FIG> is a graph showing an example of time variations in a detection value of the sensor 42A in a period when the rolling apparatus is controlled, the velocity of the strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM> (hereinafter, also simply referred to as the velocity of the strip S), and an open/close state of the gripper <NUM>. The detection value of the sensor 42A when the detection value is not less than DA indicates a horizontal distance between the sensor 42A and the strip S, which is detected by the sensor 42A, and the detection value less than DA indicates that the presence of the strip S is not detected.

In the example shown in <FIG>, the rolling apparatus <NUM> rolls the strip S at a steady velocity until time t11. Then, at time t12 later than time t11, the gripping of the tail end portion Sa by the gripper <NUM> is released (step S2). Until the time t12, the tail end and the tail end portion of the strip S are unseparated from the mandrel <NUM> as shown in <FIG>. Further, at the time t12, as shown in the graph of <FIG>, the detection value of the sensor 42A is less than DA, and the presence of the strip S is not detected.

For a while after time t14 later than the time t12, the detection value of the sensor 42A is not less than DA. That is, during this period, the presence of the strip S is detected at the position below the unwinder <NUM> by the sensor 42A.

<FIG> shows a state at a point in time after the time t12 and before the time t14, where the tail end St separates from the unwinder <NUM>, but has not reached the detection position of the sensor 42A, and the presence of the strip S is not detected by the sensor 42A. <FIG> shows a state immediately after the time t14, where the tail end St has reached below the detection position of the sensor 42A, and thus the presence of the strip S is detected by the sensor 42A. Thereafter, the presence of the strip S is no longer detected by the sensor 42A when the tail end St moves above the detection position of the sensor 42A.

The separation detection unit <NUM> determines that the tail end St separates from the unwinder <NUM> at the time t14 when the presence of the strip S is detected at the position below the unwinder <NUM> by the sensor 42A. In this case, the timing (separation timing) when the tail end St of the strip S separates separates from the unwinder <NUM> is at the time t14.

In an embodiment, whether the tail end St of the strip S separates from the unwinder <NUM> is determined by using the detection signal of the sensor 42B or 42C (see <FIG>) configured to detect the presence or absence of the strip at the position above the mandrel <NUM> of the unwinder <NUM>.

Herein, <FIG> is a graph showing an example of time variations in a detection value of the sensor 42B in the period when the rolling apparatus is controlled, the velocity of the strip S between the unwinder <NUM> and the mill rolls <NUM>, <NUM>, and the open/close state of the gripper <NUM>. The detection value of the sensor 42B when the detection value is not less than DB indicates a horizontal distance between the sensor 42B and the strip S, which is detected by the sensor 42B, and the detection value less than DB indicates that the presence of the strip S is not detected.

In the example shown in <FIG>, the rolling apparatus <NUM> rolls the strip S at the steady velocity until time t21. Then, at time t22 later than time t21, the gripping of the tail end portion Sa by the gripper <NUM> is released (step S2). Until the time t22, the tail end and the tail end portion of the strip S are unseparated from the mandrel <NUM> as shown in <FIG>. Further, at the time t22, as shown in the graph of <FIG>, the detection value of the sensor 42A is not less than DB, and the presence of the strip S is detected.

In a period after time t24 later than the time t22, the detection value of the sensor 42B is less than DB. That is, during this period, the presence of the strip S is no longer detected at the position above the unwinder <NUM> by the sensor 42B.

<FIG> shows a state at a point in time after the time t22 and before the time t24, where the tail end St separates from the unwinder <NUM>, but the strip S exists at the detection position of the sensor 42B, and thus the presence of the strip S is detected by the sensor 42B. <FIG> shows a state immediately after the time t24, where the tail end St has reached above the detection position of the sensor 42B, and thus the presence of the strip S is no longer detected by the sensor 42A.

The separation detection unit <NUM> determines that the tail end St separates from the unwinder <NUM> at the time t24 when the presence of the strip S is no longer detected at the position above the unwinder <NUM> by the sensor 42B. In this case, the timing (separation timing) when the tail end St of the strip S separates from the unwinder <NUM> is at the time t24.

Step S8 includes controlling the rotation of the motor <NUM> to stop the rotation of the mill rolls <NUM>, <NUM>, based on the velocity of the step S acquired in step S4 and the timing (separation timing) when the separation of the tail end St from the unwinder <NUM> is detected in the step S6.

By thus stopping the rotation of the mill rolls <NUM>, <NUM> based on the velocity of the strip S and the separation timing of the tail end St, the strip S can be stopped such that the tail end St is located at a desired position (for example, a position where rolling in a next pass can smoothly be stared; such as a position immediately before the deflector roll <NUM> or a position of the guide table <NUM>). Therefore, in the reverse-type rolling apparatus <NUM>, even after the tail end St separates from the unwinder <NUM>, rolling can continue until the mill rolls <NUM>, <NUM> stop, as well as rolling in the next pass can smoothly be started. Therefore, yield can be improved while suppressing an increase in time required for rolling.

Step S8 may include stopping the rotation of the mill rolls <NUM>, <NUM> based on, in addition to the velocity of the strip S and the separation timing of the tail end St, the length of the strip S from the position of the tail end St at the separation timing to the estimated stop position of the tail end St. A movement length of the strip S (that is, a movement length of the tail end St) can be expressed as a time integral of the velocity of the strip S. Therefore, the strip S can easily be stopped such that the tail end St is located at a desired estimated stop position, by controlling the rotation and the stop of the mill rolls <NUM>, <NUM> (motor <NUM>) with the rotation control unit so that the time integral of the velocity of the strip S acquired by the velocity acquisition unit <NUM> is the length of the strip S described above. Thus, it becomes easier to smoothly start rolling in the next pass.

As the length of the strip S from the position of the tail end St at the separation timing of the tail end St from the unwinder <NUM> to the estimated stop position of the tail end St, a length may be used which is geometrically obtained based on the sensors <NUM> (sensors 42A to 42C, etc.) for detecting the separation of the tail end St, the estimated stop position of the tail end St, and the like.

Step S8 may include increasing or decreasing the velocity of the strip S during a period between the separation timing of the tail end St from the unwinder <NUM> and the stopping of the mill rolls <NUM>, <NUM>, for example, as shown in <FIG> or <FIG>. In the examples shown in <FIG> and <FIG>, the velocity of the strip S is increased from time t15 or t25 after the separation timing (time t14 or t24) to time t16 or t26, and the velocity of the strip S is decreased from the time t16 or t26 to time t17 or t27 (when mill rolls <NUM>, <NUM> stop). The time required for rolling the strip S can be reduced by thus increasing the velocity of the strip S as much as possible until immediately before the strip S stops, and the tail end St is stably and easily located at the desired estimated stop position by thus decreasing the velocity of the strip S immediately before the strip S stops.

Herein, <FIG> are each a view for describing the number of windings of the strip S in the unwinder <NUM>. The number of windings of the strip S is counted based on an angular position of the gripper <NUM> around the rotational axis of the mandrel <NUM> of the unwinder <NUM>. In <FIG>, the angular position of the gripper <NUM> is the same as an angular position T where the strip S wound on the unwinder <NUM> is unwound toward the mill rolls <NUM>, <NUM> (a position where the shape of the strip S changes from an arc shape to a linear shape). That is, <FIG> shows a state where the strip S is wound on the mandrel <NUM> of the unwinder <NUM> at one round. In <FIG>, the angular position of the gripper <NUM> is a position <NUM>-degree rotated from the above-described angular position T. That is, <FIG> shows a state where the strip S is wound on the mandrel <NUM> of the unwinder <NUM> at <NUM> rounds.

In the above-described method, step S2 may include releasing the gripping of the tail end portion Sa by the gripper <NUM>, immediately before the tail end St of the strip S separates from the unwinder <NUM>.

Since tension acts on the strip S during the period when the gripper <NUM> of the unwinder <NUM> grips the tail end portion Sa of the strip S, a portion of the strip S rolled during this period can be a product. In this regard, by releasing the gripping of the tail end portion Sa by the gripper <NUM> immediately before the tail end St separates from the unwinder <NUM> as described above, the tension acting on the strip S can be maintained until immediately before the tail end St separates from the unwinder <NUM>. Thus, it is possible to improve the yield more effectively.

More specifically, step S2 may include releasing the gripping of the tail end portion Sa by the gripper <NUM> while not greater than <NUM> windings or not greater than <NUM> windings of the strip S is wound on the unwinder <NUM>.

By thus releasing the gripping of the tail end portion Sa by the gripper <NUM> while not greater than <NUM> windings or not greater than <NUM> than <NUM> windings of the strip is wound on the unwinder <NUM>, the tension acting on the strip S can be maintained until immediately before the tail end St separates from the unwinder <NUM>.

Further, step S2 may include releasing the gripping of the tail end portion Sa by the gripper <NUM> while more than <NUM> winding or <NUM> windings of the strip S is wound on the unwinder <NUM>.

The tail end St of the strip S can separate from the unwinder <NUM> when not greater than one winding of the strip S is wound on the unwinder <NUM>. In this regard, as described above, since the gripping of the tail end portion by the gripper is released while more than <NUM> winding or <NUM> windings of the strip S is wound on the unwinder <NUM>, that is, before the tail end of the strip S can separate from the unwinder, the tail end of the strip can smoothly be separated from the unwinder.

In some embodiments, the gripping of the tail end portion Sa by the gripper <NUM> may be released while not less than <NUM> winding and not greater than <NUM> windings of the strip S is wound on the unwinder <NUM>. In some embodiments, the gripping of the tail end portion Sa by the gripper <NUM> may be released while not less than <NUM> windings and not greater than <NUM> windings of the strip S is wound on the unwinder <NUM>.

In the above-described method, step S2 may include decreasing rotation speed of the mill rolls <NUM>, <NUM> in a period including a timing when the gripping of the tail end portion Sa by the gripper <NUM> is released. For example, in the example shown in <FIG> or <FIG>, the rotation speed of the mill rolls <NUM>, <NUM> is decreased in the period including the time t12 or t22 (a period from t11 to t13 or a period from t21 to t23) when the gripping of the tail end portion Sa by the gripper <NUM> is released.

By thus decreasing the rotation speed of the mill rolls <NUM>, <NUM> when the gripping of the tail end portion Sa by the gripper <NUM> is released, the rotation speed of the mill rolls <NUM>, <NUM> is maintained relatively high until immediately before the timing when the gripping of the tail end portion Sa is released. Therefore, it is possible to effectively suppress the increase in time required for rolling.

Next, a more specific configuration, of the pressing part <NUM> and the pressing control unit <NUM>, for correcting the shape of the tail end portion Sa of the strip S will be described.

As shown in <FIG>, the pressing part <NUM> is disposed so as to at least partially located, in the traveling direction of travel of the strip S, between the mill rolls <NUM>, <NUM> and a rotational axis O of the deflector roll <NUM> disposed between the unwinder <NUM> and the mill rolls <NUM>, <NUM>. The pressing part <NUM> is configured to provide the strip S with a pressing force along a strip thickness direction of the strip S.

The pressing control unit <NUM> (see <FIG>) is configured to control the operation of the pressing part <NUM>. The pressing control unit <NUM> may be configured to operate the pressing part <NUM> such that the pressing force is applied to the strip S by the pressing part <NUM>, after the tail end St of the strip S separates from the unwinder <NUM>. The pressing control unit <NUM> may be configured to apply the pressing force to the strip S by the pressing part <NUM> in a state where the mill rolls <NUM>, <NUM> are rotated (that is, in a state where the strip S is conveyed).

The tail end portion Sa of the strip S, which separates from the unwinder <NUM>, usually has a shape curved relatively greatly (strong winding habit). According to the above configuration, since, after the tail end St separates from the unwinder <NUM>, the mill rolls <NUM>, <NUM> are rotated in the state where the pressing force is applied to the strip S by the pressing part <NUM> disposed in the vicinity of the deflector roll <NUM>, the degree of curvature of the tail end portion Sa can be reduced. By thus correcting the shape of the tail end portion Sa of the strip S, rolling in the next pass can be started more smoothly. For example, it becomes easier to pass the head end portion of the strip S in the next pass (the tail end portion Sa in the previous pass) through the guide part <NUM>, or to grip the head end portion of the strip S in the next pass with the gripper of the winder (the unwinder <NUM> in the previous pass). Therefore, it is possible to effectively suppress the increase in time required for rolling.

<FIG> are each a schematic view of the pressing part <NUM> according to an embodiment.

The pressing part <NUM> shown in <FIG> includes: a pinch roll <NUM> partially disposed between the mill rolls <NUM>, <NUM> and the deflector roll <NUM> and configured to pinch the strip S together with the deflector roll <NUM>; and a push roll <NUM> disposed between the mill rolls <NUM>, <NUM> and the deflector roll <NUM> in the traveling direction of the strip S, and opposite to the pinch roll <NUM> across the strip S. The push roll <NUM> is configured to be able to provide the strip S with a pressing force along upward. As shown in <FIG>, a center of the pinch roll <NUM> in the traveling direction of the strip S (hereinafter, also simply referred to as the traveling direction) is located off the rotational axis of the deflector roll <NUM> to a side of the mill rolls <NUM>, <NUM> by a distance L1 in the traveling direction. Further, a center of the push roll <NUM> in the traveling direction is located off the center of the pinch roll <NUM> described above to the side of the mill rolls <NUM>, <NUM> by a distance L2 in the traveling direction.

In the present embodiment, the shape of the tail end portion Sa of the strip S can be corrected by pinching the strip S with the deflector roll <NUM> and the pinch roll <NUM> and rotating the mill rolls <NUM>, <NUM> in a state where the pressing force from the push roll <NUM> acts on the strip S.

The pressing part <NUM> shown in <FIG> includes a pinch roll <NUM> partially disposed between the mill rolls <NUM>, <NUM> and the deflector roll <NUM> and configured to pinch the strip S together with the deflector roll <NUM>. The pinch roll <NUM> is configured to be able to provide the strip S with a pressing force along a direction from the center of pinch roll <NUM> to the center of deflector roll <NUM>. As shown in <FIG>, a center of the pinch roll <NUM> in the traveling direction of the strip S is located off the rotational axis of the deflector roll <NUM> to the side of the mill rolls <NUM>, <NUM> by a distance L3 in the traveling direction.

In the present embodiment, the mill rolls <NUM>, <NUM> are rotated while rotating the deflector roll <NUM> and the pinch roll <NUM>, in the state where the strip S is pinched with the deflector roll <NUM> and the pinch roll <NUM> and the pressing force from the pinch roll <NUM> acts on the strip S. The shape of the tail end portion Sa of the strip S can be corrected by thus applying tension to the strip S.

The pressing part <NUM> shown in <FIG> includes a forming part <NUM> disposed between the mill rolls <NUM>, <NUM> and the deflector roll <NUM>, and a receiving part <NUM> disposed opposite to the forming part <NUM> across the strip S. The forming part <NUM> is disposed to be vertically movable. The receiving part <NUM> has a contact surface 38a that can contact the surface of the strip S in a state where the strip S is interposed between the contact surface 38a and the forming part <NUM>. Further, the receiving part <NUM> is configured to change its posture in response to the vertical movement of the forming part <NUM>. Furthermore, in the embodiment shown in <FIG>, a pinch roll <NUM>, which is configured to pinch the strip S together with the deflector roll <NUM>, is disposed above the deflector roll <NUM>.

In the exemplary embodiment shown in <FIG>, a cross-section of the forming part <NUM> has a circular shape, but the shape of the forming part <NUM> is not limited to this. For example, the cross-sectional shape of the forming part <NUM> may be rectangular, polygonal, home base, oval, or the like.

In the present embodiment, the mill rolls <NUM>, <NUM> are rotated in a state where the strip S is pinched with the deflector roll <NUM> and the pinch roll <NUM>, as well as the strip S is pinched with the forming part <NUM> and the receiving part <NUM>, and the pressing force from the forming part <NUM> is applied to the strip S by moving the forming part <NUM> downward. Whereby, the shape of the tail end portion Sa of the strip S can be corrected.

In some embodiments, the rotation control unit <NUM> may be configured to repeat the rotation and stop of the mill rolls <NUM>, <NUM> in the state where the pressing force is applied to the strip S by the pressing part <NUM>.

According to the above-described embodiment, since the rotation and stop of the pair of mill rolls <NUM>, <NUM> are repeated in the state where the pressing force is applied to the strip S by the pressing part <NUM>, the shape of the tail end portion can be corrected by shifting the position of the strip S little by little. Whereby, the shape of the tail end portion can be adjusted more finely.

<FIG> are each a view for describing an example of the procedure for correcting the shape of the tail end portion Sa while repeating the rotation and stop of the mill rolls <NUM>, <NUM> (that is, while inching the strip S). In the present example, the pressing part <NUM> shown in <FIG> is used to correct the shape of the tail end portion Sa of the strip S.

First, as shown in <FIG>, in a position of the forming part <NUM> in the traveling direction, the position of the forming part <NUM> is adjusted such that the vertical position (height) of the strip S is at the same level as the strip S between the mill rolls <NUM>, <NUM>. In this state, the mill rolls <NUM>, <NUM> are slightly rotated and stopped while the strip S is pinched with the forming part <NUM> and the receiving part <NUM>, and the pressing force from the forming part <NUM> is applied to the strip S.

Next, as shown in <FIG>, the position of the forming part <NUM> is adjusted to a position lower than the position in the case of <FIG>. In this state, the mill rolls <NUM>, <NUM> are slightly rotated and stopped while the strip S is pinched with the forming part <NUM> and the receiving part <NUM>, and the pressing force from the forming part <NUM> is applied to the strip S.

Further, as shown in <FIG>, the position of the forming part <NUM> is adjusted to a position lower than the position in the case of <FIG>. In this state, the mill rolls <NUM>, <NUM> are slightly rotated and stopped while the strip S is pinched with the forming part <NUM> and the receiving part <NUM>, and the pressing force from the forming part <NUM> is applied to the strip S. By thus increasing the amount of push-in (push-down) of the forming part <NUM>, the portion, of the strip S, in the vicinity of the tail end St having a stronger winding habit can effectively be corrected in shape.

If the tail end St of the strip S exceeds the deflector roll <NUM> and the forming part <NUM>, the forming part <NUM> may be moved upward and separated from the receiving part <NUM> to release the application of the pressing force to the strip S by the forming part <NUM>, as shown in FIG.

By thus appropriately moving the forming part <NUM> in accordance with the change in shape of the tail end portion Sa, and repeating the procedure for slightly rotating and stopping the mill rolls <NUM>, <NUM> in the state where the pressing force from the forming part <NUM> is applied to the strip S, the shape of the tail end portion Sa can effectively be corrected while shifting the position of the strip S little by little.

Hereinafter, the overview of the control device for the rolling apparatus, the rolling facility, and the control method for the rolling apparatus according to some embodiments will be described.

According to the above configuration (<NUM>), since the rotation of the rolling mill is controlled and stopped based on the timing when the separation of the tail end of the strip from the unwinder is detected and the velocity of the strip between the unwinder and the mill rolls, the strip can be stopped at an appropriate position (for example, a position where rolling in the next pass can smoothly be started). Therefore, in the reverse-type rolling apparatus, even after the tail end separates from the unwinder, rolling can continue until the rolling mill stops, as well as rolling in the next pass can smoothly be started. Therefore, the yield can be improved while suppressing the increase in time required for rolling.

(<NUM>) In some embodiments, in the above configuration (<NUM>), the separation detection unit is configured to detect the separation of the tail end from the unwinder, based on a signal from a sensor (<NUM>) capable of detecting presence or absence of the strip at a position above or below the unwinder.

According to the above configuration (<NUM>), the separation of the tail end from the unwinder can appropriately be detected by the sensor capable of detecting the presence or absence of the strip at the position above or below the unwinder. Therefore, as described in (<NUM>), the yield can be improved while suppressing the increase in time required for rolling.

(<NUM>) In some embodiments, in the above configuration (<NUM>), the rolling apparatus includes a guide part (<NUM>) for guiding the strip between the unwinder and the pair of mill rolls, and the separation detection unit is configured to detect the separation of the tail end from the unwinder, based on a signal from a sensor (<NUM>) capable of detecting the presence or absence of the strip at the same position as the guide part or a position between the guide part and the unwinder in a traveling direction of the strip, and the position above or below the unwinder.

A passage for the strip in the guide part usually has a narrow gap in the strip thickness direction, making it relatively difficult to pass the head end of the strip through. In this regard, according to the above configuration (<NUM>), since the separation of the tail end from the unwinder is detected by using the sensor capable of detecting the presence or absence of the strip at the same position as the guide part or the position between the guide part and the unwinder in the traveling direction of the strip, the tail end (that is, the head end in the next pass) of the strip is easily stopped at the same position as the guide part or the position between the guide part and the unwinder. Thus, it becomes easier to smoothly start rolling in the next pass.

(<NUM>) In some embodiments, in the above configuration (<NUM>) or (<NUM>), the separation detection unit is configured to determine, based on the signal from the sensor, that the tail end separates from the unwinder, when the presence of the strip is detected at the position below the unwinder.

According to the above configuration (<NUM>), since the separation of the tail end from the unwinder is detected based on the presence of the strip at the position below the unwinder, it is possible to promptly determine that the strip separates from the unwinder.

(<NUM>) In some embodiments, in the above configuration (<NUM>) or (<NUM>), the separation detection unit is configured to determine, based on the signal from the sensor, that the tail end separates from the unwinder, when the absence of the strip is detected at the position above the unwinder.

According to the above configuration (<NUM>), since the separation of the tail end from the unwinder is detected based on the absence of the strip at the position above the unwinder, it is possible to relatively promptly determine that the strip separates from the unwinder.

(<NUM>) In some embodiments, in any of the above configurations (<NUM>) to (<NUM>), the rotation control unit is configured to stop the rotation of the pair of mill rolls based on, in addition to the separation timing and the velocity of the strip, a length of the strip from a position of the tail end at the separation timing to an estimated stop position of the tail end.

According to the above configuration (<NUM>), since the rotation of the mill rolls is stopped based on, in addition to the separation timing of the tail end from the unwinder and the velocity of the strip, the length of the strip from the position of the tail end at the separation timing to the estimated stop position (predetermined position) of the tail end, the strip can be stopped such that the tail end is located at the desired position (estimated stop position). Thus, it becomes easier to smoothly start rolling in the next pass.

(<NUM>) In some embodiments, in any of the above configurations (<NUM>) to (<NUM>), the control device includes: a gripping control unit (<NUM>) configured to control a gripper (<NUM>) disposed in the unwinder for gripping a tail end portion (Sa) including the tail end of the strip. The gripping control unit is configured to release the gripping of the tail end portion by the gripper, immediately before the tail end separates from the unwinder.

Since tension acts on the strip during the period when the gripper of the unwinder grips the tail end portion of the strip, a portion of the strip rolled during this period can be a product. In this regard, according to the above configuration (<NUM>), since the gripping of the tail end portion by the gripper is released immediately before the tail end separates from the unwinder, the tension acting on the strip can be maintained until immediately before the tail end separates from the unwinder. Thus, it is possible to improve the yield more effectively.

(<NUM>) In some embodiments, in the above configuration (<NUM>), the gripping control unit is configured to release the gripping of the tail end portion by the gripper, while more than one winding of the strip is wound on the unwinder.

The tail end of the strip can separate from the unwinder when not greater than one winding of the strip is wound on the unwinder. In this regard, according to the above configuration (<NUM>), since the gripping of the tail end portion by the gripper is released before the tail end of the strip can separate from the unwinder and immediately before the tail end separates from the unwinder, the tail end of the strip can smoothly be separated from the unwinder, as well as the tension acting on the strip is maintained until immediately before the tail end separates from the unwinder, making it possible to improve the yield.

(<NUM>) In some embodiments, in the above configuration (<NUM>) or (<NUM>), the gripping control unit is configured to release the gripping of the tail end portion by the gripper, while not greater than two windings of the strip is wound on the unwinder.

According to the above configuration (<NUM>), since the gripping of the tail end portion by the gripper is released while not greater than two windings of the strip is wound on the unwinder, the tension acting on the strip can be maintained until immediately before the tail end separates from the unwinder. Thus, it is possible to improve the yield more effectively.

(<NUM>) In some embodiments, in any of the above configurations (<NUM>) to (<NUM>), the rotation control unit is configured to decrease rotation speed of the pair of mill rolls in a period including a timing when the gripping of the tail end portion is released by the gripping control unit.

According to the above configuration (<NUM>), since the rotation speed of the mill rolls is decreased when the gripping of the tail end portion is released, the rotation speed of the mill rolls is maintained relatively high until immediately before the gripping of the tail end portion is released. Therefore, it is possible to effectively suppress the increase in time required for rolling.

(<NUM>) In some embodiments, in any of the above configurations (<NUM>) to (<NUM>), the rolling apparatus includes a deflector roll (<NUM>) disposed between the unwinder and the pair of mill rolls, and a pressing part (<NUM>) at least partially located between the deflector roll and the pair of mill rolls in a traveling direction of the strip and configured to provide the strip with a pressing force along a strip thickness direction of the strip, the control device includes: a pressing control unit (<NUM>) configured to operate the pressing part such that the pressing force is applied to the strip by the pressing part, after the tail end separates from the unwinder, and the rotation control unit is configured to rotate the pair of mill rolls in a state where the pressing force is applied to the strip by the pressing part.

The tail end portion of the strip, which separates from the unwinder, usually has a shape curved relatively greatly (strong winding habit). According to the above configuration (<NUM>), since, after the tail end separates from the unwinder, the mill rolls are rotated in the state where the pressing force is applied to the strip by the pressing part disposed in the vicinity of the deflector roll, the degree of curvature of the tail end portion can be reduced. By thus correcting the shape of the tail end portion of the strip, rolling in the next pass can be started more smoothly, for example, it becomes easier to grip the head end portion of the strip in the next pass (the tail end portion in the previous pass) with the gripper of the winder (the unwinder in the previous pass). Therefore, it is possible to effectively suppress the increase in time required for rolling.

(<NUM>) In some embodiments, in the above configuration (<NUM>), the rotation control unit is configured to repeat the rotation and stop of the pair of mill rolls in the state where the pressing force is applied to the strip by the pressing part.

According to the above configuration (<NUM>), since the rotation and stop of the pair of mill rolls are repeated in the state where the pressing force is applied to the strip by the pressing part, the shape of the tail end portion can be corrected by shifting the position of the strip little by little. Whereby, the shape of the tail end portion can be adjusted more finely.

(<NUM>) A rolling facility (<NUM>) according to at least one embodiment of the present invention, includes: a rolling apparatus (<NUM>) including a pair of mill rolls (<NUM>, <NUM>) for rolling a metal strip (S), an unwinder (<NUM>) for unwinding the strip toward the pair of mill rolls, and a winder (<NUM>) for winding the strip rolled by the pair of mill rolls; and the control device (<NUM>) according to any one of the above (<NUM>) to (<NUM>) for controlling the rolling apparatus.

(<NUM>) A control method for a rolling apparatus according to at least one embodiment of the present invention is a control method for controlling a rolling apparatus (<NUM>) including a pair of mill rolls (<NUM>, <NUM>) for rolling a metal strip (S), an unwinder (<NUM>) for unwinding the strip toward the pair of mill rolls, and a winder (<NUM>) for winding the strip rolled by the pair of mill rolls, and using the control device in any of the above configurations (<NUM>) to (<NUM>) to perform: a rotation control step (S8) of controlling rotation of the mill rolls; a velocity acquisition step (S4) of acquiring velocity of the strip between the unwinder and the mill rolls; and a separation detection step (S6) of detecting separation of a tail end of the strip from the unwinder. The rotation control step includes stopping the rotation of the pair of mill rolls, based on a separation timing which is a timing when the separation of the tail end from the unwinder is detected in the separation detection step and the velocity of the strip acquired in the velocity acquisition step.

According to the above method (<NUM>), since the rotation of the rolling mill is controlled and stopped based on the timing when the separation of the tail end of the strip from the unwinder is detected and the velocity of the strip between the unwinder and the mill rolls, the strip can be stopped at an appropriate position (for example, a position where rolling in the next pass can smoothly be started). Therefore, in the reverse-type rolling apparatus, even after the tail end separates from the unwinder, rolling can continue until the rolling mill stops, as well as rolling in the next pass can smoothly be started. Therefore, the yield can be improved while suppressing the increase in time required for rolling.

Embodiments of the present invention were described in detail above, but the present invention is not limited thereto, and also includes an embodiment obtained by modifying the above-described embodiments and an embodiment obtained by combining these embodiments without departing from the scope of the appended claims.

Further, in the present specification, an expression of relative or absolute arrangement such as "in a direction", "along a direction", "parallel", "orthogonal", "centered", "concentric" and "coaxial" shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.

Further, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

Claim 1:
A control device (<NUM>) for controlling a rolling apparatus (<NUM>) including a pair of mill rolls (<NUM>, <NUM>) for rolling a metal strip (S), an unwinder (<NUM>) for unwinding the strip (S) toward the pair of mill rolls (<NUM>, <NUM>), and a winder (<NUM>) for winding the strip (S) rolled by the pair of mill rolls (<NUM>, <NUM>), comprising:
a rotation control unit (<NUM>) for controlling rotation of the mill rolls (<NUM>, <NUM>);
a velocity acquisition unit (<NUM>) configured to acquire velocity of the strip (S) between the unwinder (<NUM>) and the mill rolls (<NUM>, <NUM>),
characterised in that
the control device (<NUM>) comprises a separation detection unit (<NUM>) configured to detect separation of a tail end (St) of the strip (S) from the unwinder (<NUM>), and in that
the rotation control unit (<NUM>) is configured to stop the rotation of the pair of mill rolls (<NUM>, <NUM>), based on a separation timing which is a timing when the separation of the tail end (St) from the unwinder (<NUM>) is detected by the separation detection unit (<NUM>) and the velocity of the strip (S) acquired by the velocity acquisition unit (<NUM>).