Uncoiling device and uncoiling method

Abstract

To provide an uncoiling device which can inhibit coil deviation when uncoiling a coil with a pair of cradle rolls, and to provide an uncoiling method.SOLUTION: An uncoiling device for a coil having a coil crown, includes a pair of cradle rolls which uncoils the coil placed thereon. One or both of the pair of cradle rolls have a roll profile in which a center part is recessed relative to both end parts.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a coil unwinding device and a coil unwinding method using a pair of cradle rolls. [Background technology]

[0002] In a continuous processing line for steel strips (strip steel sheets), a coiled steel strip is discharged by a payoff reel, and the steel strip is continuously subjected to predetermined processing. In order to stably perform such continuous processing of steel strips, it is important to properly unwind the coil and discharge the steel strip. Therefore, various methods have been devised for unwinding the coil.

[0003] For example, in the coil unwinding method disclosed in Patent Document 1, an opener is used to open the tip of a coil attached to a payoff reel. At this time, a pressure roll, which is used to prevent bending of the unwound steel strip, is used to straighten the curl of the tip of the coil opened by the opener.

[0004] Also, for example, in the coil unwinding method disclosed in Patent Document 2, a pressure roll is used to straighten the curl of the tip of the coil that has been unwound by an opener, similar to the method disclosed in Patent Document 1. Furthermore, in the method disclosed in Patent Document 2, after unwrapping the tip of the coil, the opener moves away from the payoff reel in synchronization with the feed speed of the coil caused by the rotation of the payoff reel.

[0005] In addition, for example, in a steel strip unwinding device disclosed in Patent Document 3, after the outer periphery of the coil is pressed by a pressure roll, the pressure of the pressure roll is reduced to bring side guides into contact with both widthwise ends of the steel strip, and the steel strip is paid out from the pay-off reel. In such a case, the upward displacement of the steel strip is regulated by the pressure roll, and the widthwise displacement is regulated by the side guide, thereby stabilizing the running state of the steel strip paid out from the pay-off reel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5212191 [Patent Document 2] Patent No. 5435121 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-266121 Summary of the Invention [Problem to be solved by the invention]

[0007] In a continuous processing line, the steel strip is usually paid off from the coil by a pay-off reel as described above, but when unwinding the coil, in order to shorten the handling time and improve throughput, the tip of the coil may be paid off before the coil is inserted into the pay-off reel. Specifically, the coil is loaded on a pair of rolls (hereinafter referred to as "cradle rolls"), and the cradle rolls are rotated to rotate the coil and unwind it.

[0008] In such cases, the rotation of the coil can cause a skew (a slight cross) between the coil and the cradle roll. This skew can then cause the coil to move axially due to the thrust force. If the coil moves and shifts on the cradle roll, it can become difficult to insert the coil into the payoff reel. Furthermore, the coil may fall over on the cradle roll, potentially causing damage to the equipment.

[0009] The main cause of coil misalignment is a faulty cradle roll equipment. However, due to its nature, faulty cradle roll equipment is difficult to correct. The causes of coil misalignment will be described in detail later.

[0010] Furthermore, in order to suppress coil slippage, it is sufficient to reduce the amount of coil rotation; however, depending on the arrangement of equipment in the continuous processing line, restrictions are imposed on the amount of steel strip discharged from the tip of the coil, and there are limits to controlling the amount of coil rotation. For example, when the distance between the coil and the equipment upstream of the continuous processing line is large, it is difficult to suppress the amount of coil rotation. In other words, suppressing coil slippage poses a potential problem in that it also leads to restrictions on the configuration of the continuous processing line.

[0011] It should be noted that all of the methods disclosed in Patent Documents 1 to 3 relate to methods for unwinding a coil inserted into a payoff reel, and are not methods for unwinding a coil before inserting it into a payoff reel. Therefore, Patent Documents 1 to 3 do not address the problem of coil misalignment on the cradle roll, and naturally do not mention any method for solving this problem.

[0012] The present invention has been made in consideration of these points, and aims to provide a coil unwinding device and a coil unwinding method that can suppress coil misalignment when unwinding a coil using a pair of cradle rolls. [Means for solving the problem]

[0013] As mentioned above, the mechanism by which coil slippage occurs on the cradle roll is that the coil moves due to the thrust force caused by the skew between the coil and the cradle roll. However, the inventors further investigated the causes of coil slippage and found that the influence of coil crown is significant. The presence of coil crown reduces the contact area between the coil and the cradle roll, resulting in near-point contact (almost the same as single-point contact, but with a small contact area from the single point). This weakens the constraint on the coil by the cradle roll, causing the coil to rotate around its vertical axis (horizontal rotation), increasing the coil skew and promoting coil slippage. The inventors therefore discovered that increasing the contact area between the coil and the cradle roll is effective in suppressing the rotation around the vertical axis of the coil, which can cause coil slippage. The gist of the present invention is as follows.

[0014] The present invention is an unwinding device for a coil having a coil crown, comprising a pair of cradle rolls for loading the coil and unwinding the coil, wherein one or both of the pair of cradle rolls has a roll profile that is recessed in the center compared to both ends.

[0015] In the coil unwinding device, a side view gradient of the recess of the roll profile may be greater than a side view gradient of the crown profile of the coil.

[0016] In the coil unwinding device, the shape of the roll profile in a side view may be a rectangle, an elementary function, or a combination of a rectangle and an elementary function.

[0017] The present invention also provides a method for unwinding a coil having a coil crown, comprising the steps of loading the coil onto a pair of cradle rolls and rotating the pair of cradle rolls to unwind the coil, wherein one or both of the pair of cradle rolls has a roll profile that is recessed in the center compared to both ends.

[0018] In the coil unwinding method, a side view gradient of the recess of the roll profile may be greater than a side view gradient of the crown profile of the coil.

[0019] In the coil unwinding method, the side view shape of the roll profile may be a rectangle, an elementary function, or a combination of a rectangle and an elementary function. [Effects of the Invention]

[0020] According to the present invention, one or both of the pair of cradle rolls has a roll profile that is recessed in the center compared to both ends, thereby increasing the contact area between the recessed cradle roll and the coil. This strengthens the restraint of the coil by the cradle roll and makes it possible to suppress rotation of the coil about its vertical axis. As a result, it is possible to suppress the thrust force caused by the skew between the coil and the cradle roll, and to suppress displacement of the coil on the cradle roll. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an explanatory diagram showing an outline of the configuration of a continuous processing line. [Figure 2] FIG. 1 is a perspective view showing an outline of a partial configuration of a coil unwinding device (coil positioner). [Figure 3] FIG. 10 is a graph showing the relationship between the coil crown amount and the coil misalignment amount. [Figure 4] FIG. 10 is a diagram illustrating parallelism misalignment of the cradle roll. [Figure 5] FIG. 10 is a diagram illustrating horizontal misalignment of a cradle roll. [Figure 6] FIG. 2 is a side view showing an outline of the configuration of a cradle roll in the coil unwinding device. [Figure 7] FIG. 2 is an explanatory diagram schematically showing the geometric contact position between the coil and the cradle roll. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0023] <Configuration of continuous processing line> First, the configuration of a continuous processing line in which a coil unwinding device according to this embodiment is implemented will be described with reference to Figure 1. In this embodiment, a case will be described in which the continuous processing line 1 is a cold rolling line, as an example. In the continuous processing line 1, a coil C produced in a hot rolling process is unwound, and a steel strip S is delivered, and predetermined processes such as welding and rolling are continuously performed on the steel strip S.

[0024] Fig. 1 is an explanatory diagram showing the outline of the configuration of a continuous processing line 1. As shown in Fig. 1, the continuous processing line 1 is equipped with a coil unwinding device 10, deflector rolls 11, pinch rolls 12, a leveler 13, and a welding machine 14. Note that the continuous processing line 1 is further equipped with devices such as a rolling mill downstream of the welding machine 14 in the conveying direction, but for the sake of explanation, Fig. 1 does not show the entire continuous processing line 1, but shows the configuration from the coil unwinding device 10 to the welding machine 14.

[0025] The coil unwinding device 10 unwinds the coil C and delivers the steel strip S toward the welding machine 14. The deflector roll 11 changes the direction of the steel strip S so that the steel strip S delivered from the coil C is transported to the welding machine 14. The pinch rolls 12 are provided as a pair, one above the other, and sandwich the steel strip S between them to transport it to the welding machine 14. The leveler 13 has a plurality of work rolls arranged in a staggered pattern above and below along the transport direction of the steel strip S, and corrects the shape of the steel strip S. The welding machine 14 welds the rear end of the preceding steel strip S to the front end of the following steel strip S.

[0026] <Basic configuration of coil unwinding device> Next, the basic configuration of the coil unwinding device 10 will be described with reference to Figures 1 and 2. Figure 2 is a perspective view showing an outline of a partial configuration of the coil unwinding device 10 (coil positioner 20).

[0027] The coil unwinding device 10 is provided with a coil positioner 20 that loads the coil C and moves it to a predetermined position, and a payoff reel 21 that pays off the steel strip S from the coil C.

[0028] The coil positioner 20 is configured to be able to move the coil C horizontally and vertically, and moves the coil C sequentially to a coil receiving position P1, a leading edge feeding position P2, and a payoff reel insertion position P3. The coil positioner 20 includes cradle rolls 30a, 30b, stands 31a, 31b, motors 32a, 32b, and a moving frame 33.

[0029] Each cradle roll 30a, 30b extends in the Z direction and is arranged side by side in the X direction. That is, the pair of cradle rolls 30a, 30b is arranged substantially parallel. Each cradle roll 30a, 30b is arranged horizontally. Each cradle roll 30a, 30b is configured to be able to load a coil C so that the axial direction of the coil C faces the Z direction. Each cradle roll 30a, 30b is configured to be rotatable, and the coil C is rotated to unwind. In the example shown in FIG. 2, the cradle rolls 30a, 30b are rotated counterclockwise, and the coil C is rotated clockwise.

[0030] In the following description, the cradle roll 30a on the upstream side (entry side) of the rotation direction of the coil C (unwinding direction of the coil C) is referred to as the upstream cradle roll 30a, and the cradle roll 30b on the downstream side (exit side) of the rotation direction of the coil C is referred to as the downstream cradle roll 30b. In the example shown in Fig. 2, the rotation direction of the coil C is clockwise, the upstream cradle roll 30a is disposed on the positive side of the X direction, and the downstream cradle roll 30b is disposed on the negative side of the X direction.

[0031] As will be described later, each of the cradle rolls 30a, 30b has a recess 40 formed at least in the center in the width direction, and each of the cradle rolls 30a, 30b has a roll profile in which the center is recessed more than the both end portions. This roll profile is a characteristic feature of the present invention, and will be described in detail later.

[0032] The base 31a supports the upstream cradle roll 30a. The base 31a may have any configuration. For example, the base 31a supports both ends of the central axis 34a of the upstream cradle roll 30a in the X direction, is disposed below the upstream cradle roll 30a with a gap therebetween, and extends in the Z direction. The base 31b has a similar configuration to the base 31a, and supports the central shaft 34b of the downstream cradle roll 30b.

[0033] The motor 32a is provided below the upstream cradle roll 30a and on the negative Z-direction side of the stand 31a. The motor 32a rotates the upstream cradle roll 30a via a gear (not shown). The motor 32b has a configuration similar to that of the motor 32a, and is provided below the downstream cradle roll 30b and on the negative Z-direction side of the base 31b. The motor 32b rotates the downstream cradle roll 30b.

[0034] The moving frame 33 supports the mounts 31a and 31b. The moving frame 33 is configured to be movable in the horizontal and vertical directions by a moving mechanism (not shown).

[0035] In the coil positioner 20 having the above configuration, the positive Z direction side is the work side (WS), and the negative Z direction side is the drive side (DS).

[0036] <Continuous processing method> In the continuous processing line 1 having the above-described configuration, first, at the coil receiving position P1, the coil C is delivered to the coil positioner 20 and loaded onto the pair of cradle rolls 30a, 30b.

[0037] Next, the coil positioner 20 is moved to the leading end feed position P2. At the leading end feed position P2, the pair of cradle rolls 30a, 30b are rotated to rotate the coil C. As a result, the coil C is unwound and the leading end of the steel strip S is paid out.

[0038] The steel strip S unwound from the coil C passes through a deflector roll 11, a pinch roll 12, and a leveler 13, and is transported to a welding machine 14. In the welding machine 14, the leading end of the steel strip S is welded to the trailing end of the preceding steel strip S.

[0039] In the welding machine 14, while the rear end of the preceding steel strip S is being welded to the front end of the following steel strip S (the paid-out steel strip S), the coil positioner 20 is moved to the pay-off reel insertion position P3. At the pay-off reel insertion position P3, the pay-off reel 21 is inserted into the coil C by a moving mechanism (not shown). Thereafter, the steel strip S is paid out from the coil C inserted into the pay-off reel 21.

[0040] <Mechanism of coil misalignment> In the coil unwinding device 10 of the continuous processing line 1, from the time when unwinding of the coil C begins at the leading end feed position P2 until the payoff reel 21 is inserted into the coil C at the payoff reel insertion position P3, the coil C loaded on the pair of cradle rolls 30a, 30b moves approximately in the Z direction, which may cause coil misalignment on the cradle rolls 30a, 30b. The mechanism of coil misalignment will be explained below.

[0041] The main causes of the coil misalignment include (1) the coil crown of the coil C, (2) misalignment in parallelism of the cradle rolls 30a and 30b, and (3) misalignment in horizontality of the cradle rolls 30a and 30b.

[0042] (1) Coil crown of coil C The coil C transported to the continuous processing line 1, which is a cold rolling line, was previously produced in a hot rolling process. In the hot rolling process, when a steel plate is rolled with a rolling roll, the rolling roll undergoes elastic deformation, causing the thickness of the steel plate to increase in the center of the width direction and decrease at both ends. When the steel plate rolled in this way is wound into a coil, the plate crown of the steel plate overlaps, giving the coil C an outer shape like a barrel, with the coil diameter increasing in the center of the width direction and decreasing at both ends. The difference between the coil radius of this coil C at the center and the coil radius at the ends is the coil crown.

[0043] If the coil C has a coil crown, the coil C and the upstream cradle roll 30a will be in approximately point contact, reducing the contact area, and the coil C and the downstream cradle roll 30b will be in approximately point contact, reducing the contact area. This weakens the restraint of the coil C by the cradle rolls 30a and 30b. Furthermore, depending on the parallelism and horizontality of the cradle rolls 30a and 30b (described later) and the method of loading the coil C onto the cradle rolls 30a and 30b, the axial direction of the coil C may be tilted relative to the axial direction of each cradle roll 30a and 30b (hereinafter referred to as "coil tilt"). This coil tilt creates a difference in peripheral speed between the coil C and the upstream cradle roll 30a and also between the coil C and the downstream cradle roll 30b. In other words, relative slip occurs due to the difference in diameter between the contact surfaces caused by the coil crown, generating a rotational moment around the Y-axis in the coil C. Furthermore, because the restraint of the coil C by the cradle rolls 30a and 30b is weak, the coil C becomes more rotatable.

[0044] When the rotation moment is generated, the coil C moves, resulting in a skew (slight cross) between the coil C and each of the cradle rolls 30a and 30b. Then, the thrust force caused by this skew moves the coil C in the axial direction (approximately the Z direction).

[0045] The present inventors conducted an FEM analysis to verify the influence of coil misalignment due to coil crown. In this analysis, the parallelism (described below) of the cradle rolls 30a and 30b (described below) was set to 4 mm and the horizontality (described below) was set to 0 (zero) mm, as equipment-related disturbances that could cause coil misalignment. Figure 3 shows the results of this analysis, showing the relationship between the amount of coil crown (horizontal axis) and the amount of coil misalignment (vertical axis). Referring to Figure 3, when there was no coil crown, almost no coil misalignment occurred. In contrast, as the amount of coil crown increased, the amount of coil misalignment increased. It is presumed that the reason for the increased coil misalignment when there was coil crown is the geometric constraint of the coil C by the cradle rolls 30a and 30b, as described above. As described above, it was verified that coil misalignment occurs due to coil crown.

[0046] (2) Parallelism misalignment of the cradle rolls 30a and 30b Typically, the cradle rolls 30a and 30b are arranged parallel to one another. However, due to equipment design issues, there is a certain degree of error, and the cradle rolls 30a and 30b are not arranged perfectly parallel to one another. That is, as shown in FIG. 4, the distance Lws between the cradle rolls 30a and 30b in the X direction on the positive Z-direction side (WS side) is different from the distance Lds between the cradle rolls 30a and 30b in the X direction on the negative Z-direction side (DS side). In the example of FIG. 4, the distance Lws is greater than the distance Lds, and the cradle rolls 30a and 30b are arranged in a V-shape in plan view. In the following description, the absolute value of the difference between the distance Lws between the cradle rolls 30a and 30b on the WS side and the distance Lds between the cradle rolls 30a and 30b on the DW side is referred to as parallelism (=|Lws - Lds|). The state in which the cradle rolls 30a, 30b are parallel to each other and are not parallel to each other is called parallelism misalignment.

[0047] If there is misalignment in the parallelism of the cradle rolls 30a, 30b, skew occurs between the coil C and the cradle rolls 30a, 30b, and the thrust force caused by this skew generates a rotational moment about the Y axis in the coil C. When this rotational moment occurs, the skew between the coil C and the cradle rolls 30a, 30b is further accelerated, and the thrust force also increases. Then, the thrust force caused by this skew causes the coil C to move in the axial direction (approximately the Z direction).

[0048] (3) Horizontal misalignment of the cradle rolls 30a and 30b Typically, the cradle rolls 30a, 30b are arranged horizontally. However, due to equipment design issues, there is a certain degree of error, and the arrangement of the cradle rolls 30a, 30b is not completely horizontal. That is, as shown in FIG. 5 , with a horizontal axis passing through the center of the width of the upstream cradle roll 30a as a reference, there is a vertical distance Hws in the Y direction from the horizontal on the positive Z-direction side (WS side) of the upstream cradle roll 30a, and there is also a vertical distance Hds in the Y direction from the horizontal on the negative Z-direction side (DS side) of the upstream cradle roll 30a. In the following description, the absolute value of the difference between the vertical distance Hws on the WS side of the upstream cradle roll 30a and the vertical distance Hds on the DW side is referred to as the horizontality (=|Hws-Hds|). Similarly, for the downstream cradle roll 30b, the absolute value of the difference between the vertical distance Hws on the WS side and the vertical distance Hds on the DW side is referred to as the horizontality. Furthermore, the state in which the cradle rolls 30a and 30b are not horizontal is called horizontal misalignment.

[0049] If there is misalignment in the horizontality of each of the cradle rolls 30a, 30b, the thrust force due to gravity will cause the coil C to move in the axial direction (approximately in the Z direction).

[0050] As described above, the main causes of coil misalignment include (1) the coil crown of the coil C, (2) misalignment in parallelism of the cradle rolls 30a and 30b, and (3) misalignment in horizontality of the cradle rolls 30a and 30b. Analysis by the present inventors has revealed that the amount of coil misalignment caused by (3) misalignment in horizontality of the cradle rolls 30a and 30b is extremely small compared to the amount of coil misalignment caused by (1) the coil crown of the coil C and (2) misalignment in parallelism of the cradle rolls 30a and 30b.

[0051] Therefore, in the present invention, the following factors are considered to cause coil misalignment: (1) the coil crown of the coil C and (2) the parallelism misalignment of the cradle rolls 30a, 30b. Note that (1) the coil crown of the coil C inevitably occurs in the pre-treatment hot rolling process. Furthermore, errors in the equipment design of the cradle rolls 30a, 30b cannot be avoided, and (2) the parallelism misalignment of the cradle rolls 30a, 30b also inevitably occurs. Moreover, since the parallelism of the cradle rolls 30a, 30b increases during operation due to wear and tear on the equipment, it is difficult to control in terms of productivity and work efficiency.

[0052] <Method for preventing coil misalignment> In the present invention, (1) attention is focused on coil misalignment caused by the coil crown of the coil C and the coil misalignment is suppressed. As described above, the presence of the coil crown reduces the contact area between the coil C and each cradle roll 30a, 30b. This weakens the coil restraint by the cradle rolls 30a, 30b, causing the coil C to rotate about the Y-axis, increasing the skew of the coil C and promoting the coil misalignment. Therefore, the inventors increased the contact area between the coil C and each cradle roll 30a, 30b to suppress the rotation of the coil C about the Y-axis, which is the trigger for the coil misalignment. Specifically, the roll profile of each cradle roll 30a, 30b is made concave.

[0053] (Coil unwinding device) 6 is a side view showing the outline of the configuration of each cradle roll 30a, 30b in the coil unwinding device 10 according to this embodiment. Each cradle roll 30a, 30b has a recess 40 formed at least in the center in the width direction, and has a roll profile in which the center is recessed compared to both end portions.

[0054] 6, the side view shape of each of the cradle rolls 30a, 30b is a quadratic function, but this is not restrictive. For example, the side view shape of each of the cradle rolls 30a, 30b may be an elementary function such as a linear function to a cubic function, a rectangle, or a combination of a rectangle and an elementary function.

[0055] 6, the recesses 40 are formed from the center to both ends of each cradle roll 30a, 30b, but the range in which the recesses 40 are formed is arbitrary as long as the recesses 40 are formed at least in the center. For example, the recesses 40 may be formed in the center of each cradle roll 30a, 30b, and the area from the recesses 40 to the ends may be formed flat.

[0056] If a coil crown exists in the coil C, the coil C has a crown profile in which the coil diameter at the center in the width direction is larger than the coil diameter at both ends. When the side view shape of the cradle roll is flat as in the conventional case, the side view gradient of the roll profile of the cradle roll is 0 (zero), and there is a large difference between the side view gradient and the side view gradient of the crown profile of the coil. Then, the center of the coil and the cradle roll come into approximate point contact at one point, so the contact area between the coil and the cradle roll is small.

[0057] In contrast, when recesses 40 are formed in each cradle roll 30a, 30b as in this embodiment, the difference between the side view gradient Sr of the recesses 40 in the roll profile of each cradle roll 30a, 30b calculated by the following formula (1) and the side view gradient Sc of the crown profile of the coil C calculated by the following formula (2) becomes smaller than the difference in side view gradient when the side view shape of the cradle roll is flat as in the conventional case described above. Sr=R / Dr (1) Sc = Cr / Dc = (Pe - Pc) / Dc (2) however, R: depth of recess 40, Dr: length from the center of each cradle roll 30a, 30b in the width direction to the end of the recess, Cr: Coil crown of coil C, Dc: Length from the center to the end of the width direction of coil C, Pe: Coil radius at the end of coil C, Pc: Coil radius at the center of coil C.

[0058] The number of contact points between the coil C and each cradle roll 30a, 30b is determined depending on the side view shape of each cradle roll 30a, 30b and the formation range of the recess 40, but as described above, the difference between the side view gradients Sr and Sc can be reduced, making it possible to increase the contact area.

[0059] (How to unwind the coil) As shown in FIG. 1, in the coil unwinding device 10, first, at the coil receiving position P1, the coil C is delivered to the coil positioner 20 and loaded onto a pair of cradle rolls 30a, 30b.

[0060] Next, the coil positioner 20 is moved to the leading end feed position P2. At the leading end feed position P2, the pair of cradle rolls 30a, 30b are rotated to rotate the coil C. As a result, the coil C is unwound and the leading end of the steel strip S is paid out.

[0061] When unwinding the coil C in this way, if the roll profile of each cradle roll 30a, 30b is concave, the contact area between the coil C and each cradle roll 30a, 30b is large as described above, and therefore the constraint of the coil C by each cradle roll 30a, 30b is strong. This suppresses rotation of the coil C about the Y axis and reduces the thrust force caused by the skew between the coil C and each cradle roll 30a, 30b. As a result, axial movement of the coil C can be suppressed, and coil misalignment can be suppressed.

[0062] Next, the coil positioner 20 is moved to the payoff reel insertion position P3. At the payoff reel insertion position P3, the payoff reel 21 is inserted into the coil C by a moving mechanism (not shown). Thereafter, the steel strip S is paid out from the coil C inserted into the payoff reel 21.

[0063] <Action and effect> According to the above embodiment, even if there is a parallelism misalignment between the cradle rolls 30a and 30b when unwinding the coil C, the contact area between the coil C and each cradle roll 30a and 30b can be increased to suppress rotation and skew of the coil C around the Y-axis caused by the coil crown of the coil C, thereby suppressing coil misalignment.

[0064] It is preferable that the side view gradient Sr of the recesses 40 in the roll profile of each cradle roll 30a, 30b is larger than the side view gradient Sc of the crown profile of the coil C. In this case, the coil C and each cradle roll 30a, 30b contact each other at least at two locations on both end sides. That is, the number of contact locations between the coil C and each cradle roll 30a, 30b is two or more. This allows the contact area to be further increased, thereby enhancing the effect of suppressing coil misalignment.

[0065] Furthermore, in the above embodiment, the recesses 40 are formed in both the cradle rolls 30a, 30b, but the recesses 40 may be formed in one of the cradle rolls 30a, 30b, and the side view shape of the other may be flat. Even in such a case, the contact area between the cradle rolls 30a, 30b in which the recesses 40 are formed and the coil C is increased, so the effect of suppressing coil slippage can be obtained. Note that the effect of suppressing coil slippage can be obtained whether the recesses 40 are formed in the upstream cradle roll 30a or the downstream cradle roll 30b.

[0066] While one embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0067] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects. [Example]

[0068] An experiment was conducted to verify the coil misalignment suppression effect of the present invention. This verification was carried out using a coil loaded on a pair of cradle rolls, similar to the coil positioner shown in Figure 2.

[0069] In this verification, the maximum coil misalignment amount was measured when 20m of each of ten coils with outer diameters of 1.2m to 2.0m and widths of 1.0m to 1.6m was unwound. In this case, the coil misalignment amount was measured as the absolute value of the amount of axial movement of the coil from the position of the coil when it was loaded on a pair of cradle rolls. When the crown of a coil with a width of 1.5m was measured, it was found to be 3mm, and the side view gradient of the crown profile was 4.0 x 10 -3 It was.

[0070] The diameter of each cradle roll is 350 mm, and the roll width (body length) is 1 m. The distance between the axes of the WS side of the pair of cradle rolls is 830 mm. The distance between the axes of the WS side ends of the pair of cradle rolls is 4 mm larger than the distance between the axes of the DS side ends. In other words, the pair of cradle rolls were arranged non-parallel (in a V-shape), causing parallelism misalignment.

[0071] The conditions of each cradle roll (shape and side view gradient) are as shown in Table 1. In Example 1, both of the pair of cradle rolls have a roll profile in which the depth of the recess is 1 mm and the shape of the recess in side view is a quadratic function. The side view gradient of the recess in the roll profile is 2.0×10 -3 is. In Example 2, both of the pair of cradle rolls have a roll profile in which the depth of the recess is 6 mm and the shape of the recess in side view is a quadratic function. The slope of the recess in the roll profile in side view is 1.2×10 -2 is. In Example 3, the upstream cradle roll has a roll profile in which the depth of the recess is 6 mm, the shape of the recess in side view is a quadratic function, and the side view gradient of the recess in the roll profile is 1.2 × 10 -2 The downstream cradle roll has a roll profile in which the shape of the cradle roll in a side view is flat. In Example 4, both of the pair of cradle rolls have a roll profile in which the recess depth is 1.7 mm in the range of 200 mm from the center and the recess shape in side view is rectangular, and in the range of 200 mm to 500 mm from the center, the roll profile has a tapered shape of a linear function. The side view gradient of the recess of the roll profile is 1.7 × 10 -2 is.

[0072] [Table 1]

[0073] As shown in Figure 7, coils were loaded on a pair of cradle rolls so that the widthwise center of each cradle roll corresponded to the widthwise center of the coil. Figure 7 shows the roll profile of the cradle roll and the crown profile of the coil, with the horizontal axis indicating the position from the widthwise center (center) and the vertical axis indicating the vertical position. Contact between the cradle roll and the coil was confirmed using pressure-sensitive paper, and it was found that in Example 1, the cradle roll and the coil were in contact at the center. In Examples 2 and 4, the cradle roll and the coil were not in contact at the center, but were in contact at two or more locations in the width direction. In Example 3, the upstream cradle roll and the coil were also in contact at two or more locations in the width direction at the center.

[0074] Table 1 shows the amount of coil misalignment in Examples 1 to 4 and the Comparative Example. The amount of coil misalignment is defined as the movement of the coil toward the WS side on the cradle roll. In all of Examples 1 to 4, coil misalignment was significantly reduced compared to the Comparative Example.

[0075] In Example 1, the cradle roll and the coil contacted at one point in the center, but the contact area between the cradle roll and the coil was large, so the amount of coil misalignment in Example 1 was smaller than that in the comparative example.

[0076] In Example 2, the side view gradient of the recess in the roll profile of the cradle roll is larger than the side view gradient of the crown profile of the coil, so the cradle roll and the coil come into contact at two or more points, and the contact area between the cradle roll and the coil is larger than that of Example 1. Therefore, the coil misalignment amount in Example 2 is even smaller than that of Example 1.

[0077] In Example 3, of the pair of cradle rolls, a recess is formed in the upstream cradle roll and the downstream cradle roll has a flat profile, but even in this case, the coil deviation amount in Example 3 is smaller than the coil deviation amount in the comparative example.

[0078] In Example 4, the shape of the recesses in the cradle roll in side view is different from the shapes of the recesses in Examples 1 to 3, but even in this case, the amount of coil deviation in Example 4 is smaller than that in the comparative example.

[0079] From the above results, it was confirmed that the amount of coil slippage can be suppressed when at least one of a pair of cradle rolls has a roll profile that is more recessed in the center than in both end portions. In this case, the amount of coil slippage can be suppressed regardless of the side view shape of the recess, regardless of the shape. Furthermore, it was confirmed that the amount of coil slippage can be further suppressed when the side view gradient of the recess in the roll profile of the cradle roll is greater than the side view gradient of the crown profile of the coil. [Industrial Applicability]

[0080] The present invention is useful when unwinding a coil using a pair of cradle rolls. [Explanation of symbols]

[0081] 1 Continuous processing line 10 Coil unwinding device 11 Deflector roll 12 Pinch Roll 13 Leveller 14. Welding machine 20 Coil Positioner 21 Payoff Reel 30a Upstream cradle roll 30b Downstream cradle roll 31a, 31b Mounting stand 32a, 32b motor 33 Moving Frame 34a, 34b center axis 40 recess C coil P1 Coil receiving position P2 Lead edge feed position P3 Payoff reel insertion position S steel strip

Claims

1. 1. An unwinding device for a coil having a coil crown, comprising: a pair of cradle rolls for loading the coil and unwinding the coil; A coil unwinding device, characterized in that one or both of the pair of cradle rolls has a roll profile that is recessed in the center compared to both end portions.

2. 2. The coil unwinding device according to claim 1, wherein the side slope of the concave portion of the roll profile is greater than the side slope of the crown profile of the coil.

3. 3. The coil unwinding device according to claim 1, wherein the shape of the roll profile in side view is a rectangle, an elementary function, or a combination of a rectangle and an elementary function.

4. 1. A method for unwinding a coil having a coil crown, comprising: loading the coil onto a pair of cradle rolls; and rotating the pair of cradle rolls to unwind the coil. A coil unwinding method, characterized in that one or both of the pair of cradle rolls has a roll profile that is recessed in the center compared to both end portions.

5. 5. The coil unwinding method according to claim 4, wherein the side slope of the concave portion of the roll profile is greater than the side slope of the crown profile of the coil.

6. 6. The coil unwinding method according to claim 4, wherein the side view shape of the roll profile is a rectangle, an elementary function, or a combination of a rectangle and an elementary function.

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