JP5821875B2 - Sheet bar winding device and sheet bar winding method - Google Patents

Description

  The present invention relates to a sheet bar winding device and a sheet bar winding method for winding a sheet bar in a coil box in a hot rolling line.

  Generally, in a hot rolling line, a slab extracted from a heating furnace is rolled into a sheet bar by a roughing mill. The sheet bar may be wound in a coil shape by a coil box, and after the temperature difference in the longitudinal direction is eased, the sheet bar may be rewound and finish rolled.

  In the following description, a portion of the sheet bar that is wound in a coil shape is simply referred to as a “coil”, and a portion that is not wound on the upstream side of the coil is referred to as a “sheet bar”.

  In the coil box, the sheet bar is wound by rotating the coil while being supported by two cradle rolls. A back tension is applied to the sheet bar on the upstream side of the coil so that winding failure does not occur in the coil.

  Specifically, the peripheral speed of the cradle roll is set higher than the peripheral speed of the coil. Thereby, the sheet bar is pulled downstream by the rotation of the cradle roll. On the other hand, on the upstream side of the sheet bar, friction is generated between the sheet bar and the transport roll due to the weight of the sheet bar. The seat bar is pulled upstream by this frictional force. As a result, the seat bar is pulled from both upstream and downstream sides, and tension (back tension) is applied to the seat bar. Thereby, telescope winding can be prevented by applying tension to the seat bar.

  However, at the tail end of the sheet bar, the length of the portion of the sheet bar that is not coiled is gradually shortened, and the friction between the sheet bar and the transport roll is reduced. Therefore, the force pulling the seat bar upstream becomes weak, and the back tension does not act. As a result, the coiled sheet bar wound up at the tail end of the sheet bar may be telescopic.

  When the telescopic sheet bar is rewound, the sheet bar becomes off-center with respect to the rolling line, and the sheet bar meanders toward the drive side or the operator side. If the sheet bar meanders, it will cause troubles such as drawing in the finishing mill. If the telescope winding becomes severe, the coil may turn after winding and the line may stop.

  Although not a coil box, Patent Document 1 discloses a coil rotating device that takes into account the prevention of telescope winding. In Patent Document 1, telescoping is prevented by using a downstream cradle roll as a drive roll and an upstream cradle roll as an idle roll.

Japanese Patent Publication No.53-5855

  Here, in a general coil box, a cradle roll for winding a sheet bar is also used as a transport roll for feeding the coil and the sheet bar to a subsequent process. Therefore, when the technique disclosed in Patent Document 1 is applied to the coil box, that is, when the upstream cradle roll of the coil box is idled, it is necessary to separate the upstream cradle roll from the drive mechanism during idling. Requires equipment modification. Further, in the method disclosed in Patent Document 1, it is still impossible to apply the back tension at the tail end portion of the sheet bar, and there is a possibility that telescope winding occurs.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a sheet bar winding device and a sheet bar winding method for stably winding a sheet bar.

The present invention has been made to achieve the above object, and has the following features.
[1] A sheet bar winding device for winding a sheet bar into a coil shape,
Having two or more cradle rolls rotating while supporting the coil;
The sheet bar winding device according to claim 1, wherein a lead ratio of the downstream cradle roll to the coil is larger than a lead ratio of the upstream cradle roll to the coil.
[2] The lead rate of the downstream cradle roll with respect to the coil after the tail end of the sheet bar passes through the rough rolling mill provided upstream of the sheet bar winding device is the upstream cradle roll. The sheet bar winding device according to [1], wherein the lead ratio of the coil is greater than the lead ratio of the coil.
[3] The sheet bar winding device according to [1] or [2], wherein the lead rate of the downstream cradle roll is greater than 0% and 20% or less than the lead rate of the upstream cradle roll.
[4] In a sheet bar winding method for winding a sheet bar into a coil shape,
Rotate while supporting the coil with two or more cradle rolls,
A sheet bar winding method, wherein a lead ratio of the downstream cradle roll to the coil is larger than a lead ratio of the upstream cradle roll to the coil.
[5] The lead rate of the downstream cradle roll with respect to the coil after the tail end of the sheet bar has passed through the rough rolling mill provided upstream of the sheet bar winding device, and the upstream cradle roll The sheet bar winding method according to [4], wherein the lead rate of the coil is larger than the lead ratio of the coil.
[6] The sheet bar winding method according to [4] or [5], wherein the lead rate of the downstream cradle roll is greater than 0% and 20% or less than the lead rate of the upstream cradle roll .
[7] A method for producing a steel sheet using the sheet bar winding method according to any one of [4] to [6].

  According to the sheet bar winding device and the sheet bar winding method according to the present invention, the sheet bar can be stably wound.

It is a figure showing composition of a sheet bar winding device concerning an embodiment of the invention. It is the figure which showed the force which acts on a coil from a cradle roll. It is a figure which shows the relationship between a lag rate and a friction coefficient. It is a figure which shows the thrust force which acts on a coil from a cradle roll. It is a figure which shows the force which acts on a coil from a cradle roll. FIG. 6 is a diagram showing a relationship between a read rate and a coefficient μ (λ) / λ.

  Hereinafter, a sheet bar winding device and a sheet bar winding method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a sheet bar winding device according to an embodiment of the present invention. In a hot rolling facility that is a steel plate manufacturing facility, a roughly rolled sheet bar is wound up by a coil box 1 and the temperature difference in the longitudinal direction is relaxed, and then it is rewound and finish rolled. Hereinafter, a portion of the sheet bar that is wound in a coil shape is referred to as a “coil”, and a portion that is not wound on the upstream side of the coil is referred to as a “sheet bar”.

  The coil box 1 is provided with two cradle rolls 2 and 3. Two or more cradle rolls may be provided. The coil 4 is supported by two cradle rolls, an upstream cradle roll 2 and a downstream cradle roll 3. The upstream cradle roll 2 and the downstream cradle roll 3 rotate in the same direction, thereby rotating the coil 4 and winding the sheet bar 5 in a coil shape.

  The peripheral speed of the cradle rolls 2 and 3 is set higher than the peripheral speed of the coil 4. In other words, the cradle rolls 2 and 3 have a predetermined lead rate with respect to the peripheral speed of the coil 4. Thereby, the sheet bar 5 is pulled downstream by the rotation of the cradle rolls 2 and 3. On the other hand, friction is generated between the sheet bar 5 and the transport roll 6 on the upstream side of the sheet bar 5 due to the weight of the sheet bar 5. The seat bar is pulled upstream by this frictional force. Thereby, the seat bar 5 is pulled from both upstream and downstream sides, and tension (back tension) is applied.

However, at the tail end of the sheet bar, the length of the sheet bar portion that is not wound in a coil shape is gradually shortened, and the friction between the sheet bar 5 and the transport roll 6 is reduced. Therefore, the force pulling the seat bar 5 upstream becomes weak, and the back tension does not act. Therefore, in the sheet bar winding device according to the present embodiment, the lead rate λ ₁ of the downstream cradle roll 3 is set to be larger than the lead rate λ _{2 of} the upstream cradle roll 2, A back tension is applied to the downstream cradle roll 3.

After the tail end of the sheet bar passes through the rough rolling mill provided upstream of the sheet bar winding device, the lead rate λ ₁ of the downstream cradle roll 3 is changed to the lead rate λ ₁ of the upstream cradle roll 2. You may set so that it may become larger than _two . While the upstream side of the sheet bar 5 is being rolled by the roughing mill, the portions that are sequentially rolled in the sheet bar 5 are sequentially fixed by the roughing mill. Therefore, when the coil box 1 winds the sheet bar 5, back tension is applied to the sheet bar 5 between the rough rolling mill and the coil box 1.

On the other hand, after the tail end of the sheet bar has passed through the roughing mill provided upstream of the sheet bar winding device, the upstream side of the sheet bar 5 does not come into contact with the roughing mill. Compared with the rolling by the rolling mill, the back tension is reduced and the winding deviation is likely to occur. Therefore, after passing through the rough rolling mill provided upstream of the sheet bar winding device, the lead rate λ ₁ of the downstream cradle roll 3 is set larger than the lead rate λ ₂ of the upstream cradle roll 2, and the upstream side By applying a back tension between the cradle roll 2 and the downstream cradle roll 3, winding deviation can be reduced or prevented.

Here, the lead ratio indicates the peripheral speed of the cradle roll with respect to the peripheral speed of the coil. The lead ratio λ ₁ of the downstream cradle roll 3 and the lead ratio λ 2 of the upstream cradle roll ₂ are expressed by the following equations. Is done.

In the above equation, v ₁ is the peripheral speed of the downstream cradle roll 3, and v ₂ is the peripheral speed of the upstream cradle roll 2. Further, v is the peripheral speed of the coil.

The lead rate λ ₁ of the downstream cradle roll 3 is preferably greater than 0% and less than 20% with respect to the lead rate λ ₂ of the upstream cradle roll 2. Read rate lambda ₁ on the downstream side cradle rolls 3 relative to the upstream side lead rate lambda ₂ Cradle roll 2, by increasing the degree over 0% to 20%, it is possible to satisfactorily reduce the telescope winding. If it is 20% or less, wrinkles will not occur in the steel sheet, and roll wear can be reduced. In order to make such an effect more remarkable, it is preferable to increase the lead rate λ ₁ of the downstream cradle roll 3 by about 5% to 10% with respect to the lead rate λ ₂ of the upstream cradle roll 2. .

Thus, by making the lead rate λ ₁ of the downstream cradle roll ₂ larger than the lead rate λ ₂ of the upstream cradle roll 3, meandering of the coil 4 can be reduced and stable winding can be performed. . The reason will be described below.

FIG. 2 is a diagram showing the force acting on the coil from the cradle roll. From the upstream cradle roll 2, a vertical drag N ₂ works from the contact point with the coil 4 toward the rotation center of the coil 4. Similarly, from the downstream cradle roll 3, a vertical drag N ₁ works from the contact point with the coil 4 toward the rotation center of the coil 4. Here, the vertical drag N ₁ of the downstream cradle roll 3 is larger than the vertical drag N ₂ of the upstream cradle roll 2. This is because the frictional force of the back tension and cradle rolls, the coil 4 is strongly pressed against the downstream cradle rolls 3 from the upstream side cradle roll 2, the normal force N ₁ of the downstream cradle rolls 3 of the upstream cradle roller 2 This is because the larger than normal force N _2. Since the vertical drag N ₁ is more parallel to the tension direction of the seat bar 5 than the vertical drag N _2, it may be considered that the vertical drag N ₁ is larger.

Here, the friction coefficient between the cradle rolls 2 and 3 and the coil is μ. Friction force F ₁ acts from the downstream cradle roll 3 to the coil 4, and friction force F ₂ acts from the upstream cradle roll 2 to the coil 4.

The friction coefficient μ (λ ₁ ) is a function having the lead rate λ ₁ as an argument, and can be expressed by the following equation, for example.

Here, μ ₀ is a dynamic friction coefficient (constant), and λ ₀ is a limit slip ratio (constant). In the steel-to-steel contact state, the values are generally about μ ₀ ≈0.2 to 0.3 and λ ₀ ≈0.01. FIG. 3 is a diagram showing the relationship between the lead rate and the friction coefficient when μ ₀ = 0.25 and λ ₀ = 0.01. If the lead rate is larger than the limit slip rate, the friction coefficient becomes the same as the dynamic friction coefficient.

FIG. 4 is a diagram showing the thrust force acting on the coil from the cradle roll. One cause for causing the winding deviation of the coil 4 is that a thrust force acting in the axial direction of the coil 4 is generated from the cradle roll. Here, the thrust direction is y, the thrust force acting on the coil 4 from the upstream cradle roll 2 is F _y2 , and the thrust force acting on the coil 4 from the downstream cradle roll 3 is F _y1 . The thrust forces F _y1 and F _y2 of the cradle roll can be obtained as follows.

  FIG. 5 is a diagram showing the force acting on the coil from the cradle roll. The x-axis indicates the winding direction of the coil 4 when no meandering occurs in the coil 4. In FIG. 5, it is assumed that the coil 4 is wound with an inclination with respect to the winding direction, and the inclination angle of the coil 4 at the point where the cradle roll and the coil 4 are in contact with each other is δ [rad]. Further, the peripheral speed of the coil 4 at the origin is assumed to be v [m / s]. It is assumed that the inclination angle of the coil 4 at the contact point between the upstream cradle roll 2 and the coil 4 and the inclination angle of the coil 4 at the contact point between the upstream cradle roll 2 and the coil 4 are both δ.

The frictional force F works from the cradle roll to the coil 4. The component F _{y in the} axial direction of the friction force F can be expressed by the following equation.

When this is considered for each of the upstream cradle roll 2 and the downstream cradle roll 3, the component F _{y1 in the} axial direction of the frictional force F ₁ acting from the downstream cradle roll 3 to the coil 4 and the upstream cradle roll 2 component F _y2 thrust axis direction of the frictional force F ₂ acting to the coil 4 can be expressed by the following equation.

  Then, substituting Equations (3) and (4) into Equations (7) and (8) gives the following equations.

  FIG. 6 is a diagram showing the relationship between the lead rate and μ (λ) / λ, which is the coefficient of variation of the component F of the frictional force F in the thrust axis direction. As shown in FIG. 6, when the lead rate is zero (the peripheral speed of the cradle roll and the peripheral speed of the coil match), the coefficient μ (λ) / λ becomes a maximum. This means that when the lead rate is zero, the frictional thrust force can potentially increase, which increases the possibility of telescoping or turning.

  In other words, if the lead rate is increased, the frictional thrust force can be reduced potentially, and the occurrence of telescope winding and turning can be suppressed.

Here, as described above, the vertical efficacy N ₁ of the downstream cradle roll 3 is larger than the vertical efficacy N ₂ of the upstream cradle roll 2.

Therefore, when the upstream cradle roll 2 and the downstream cradle roll 3 have the same lead rate, the component F _{y1 in the} axial direction of the frictional force F ₁ acting from the downstream cradle roll 3 to the coil 4 is equal to the upstream cradle roll 2. from greater than component F _y2 thrust axis direction of the frictional force F ₂ acting to the coil 4.

Therefore, in the present invention, the lead rate λ ₁ of the downstream cradle roll 3 is set to be larger than the lead rate λ ₂ of the upstream cradle roll 2. In other words, the peripheral speed v ₁ of the downstream cradle roll 3 is made larger than the peripheral speed v ₂ of the upstream cradle roll 2.

Thus, a thrust direction component F _y1 of the frictional force F ₁ acting from the downstream side cradle rolls 3 to the coil 4, the component F _y2 thrust axis direction of the frictional force F ₂ acting from the upstream side cradle roll 2 to the coil 4 It is possible to reduce the winding failure of the sheet bar 5 to the same extent. Thereby, the sheet bar 5 can be stably wound into a coil shape.

  Further, when the present invention is applied to the coil box 1 at the front stage of the continuous finish rolling mill in the endless rolling process, the following effects can be obtained. In the preceding stage of the continuous finishing mill, the tips and tail ends of the plurality of coils 4 wound up by the coil box 1 are sequentially connected by a welding machine. The steel strip connected by the welding machine is supplied to the continuous finishing mill as a continuous material to be rolled, and the rolling process is performed. Here, when there is a winding deviation in the coil, when the coil is rewound and supplied to the continuous finishing rolling mill, the sheet bar becomes off-center with respect to the rolling line, and the sheet bar meanders to the drive side or the operator side. . If the sheet bar meanders, it will cause troubles such as drawing in the finishing mill. Further, if the winding deviation becomes severe, the coil may turn after winding. When the coil turns in this way, the rolling line including the welding machine and the endless finishing rolling mill may have to be stopped.

  In response to such a problem, if the present invention is applied to the coil box 1 in the preceding stage of the continuous finishing mill in the endless rolling process, the occurrence of winding misalignment can be reduced or prevented. Stopping of the rolling line can be prevented. Thereby, productivity of a steel plate can be improved.

  The sheet bar 5 was wound using conventional operating conditions and operating conditions to which the present invention was applied.

  Under conventional operating conditions, the lead ratios of the upstream and downstream cradle rolls 2 and 3 with respect to the coil 4 were both 17%. Specifically, the peripheral speed of the coil 4 was set to 250 mpm, and the peripheral speeds of the upstream and downstream cradle rolls 2 and 3 were both 293 mpm.

  At the tail end of the seat bar 5, the back tension decreased and the peripheral speed of the coil 4 accelerated, and the peripheral speed of the coil 4 became 293 mpm, which was substantially the same as the peripheral speed of the cradle rolls 2 and 3. Then, telescope winding occurred at the tail end of the seat bar 5.

  On the other hand, under the operating conditions to which the present invention was applied, the lead rate of the downstream cradle roll 3 was 17%, and the lead rate of the upstream cradle roll 2 was 10%. Specifically, the peripheral speed of the coil 4 was set to 250 mpm. The peripheral speed of the downstream cradle roll 3 was set to 293 mpm, and the peripheral speed of the upstream cradle roll 2 was set to 275 mpm.

  At the tail end portion of the seat bar 5, the peripheral speed of the coil 4 was accelerated, and the peripheral speed of the coil 4 and the peripheral speed of the upstream cradle roll 2 were approximately the same 275 mpm. However, telescope winding did not occur under the operating conditions to which the present invention was applied. This is because the frictional force in the thrust direction of the cradle roll that generates telescope winding is reduced by 28% compared to the conventional operating conditions.

  From this result, it was found that the present invention can stably wind up the sheet bar by reducing the frictional force in the thrust direction of the cradle roll that generates telescope winding.

1 Coil box 2 Upstream cradle roll 3 Downstream cradle roll 4 Coil 5 Sheet bar 6 Transport roll

Claims (6)

A sheet bar winding device for winding a sheet bar into a coil shape,
Having two or more cradle rolls rotating while supporting the coil;
The sheet bar winding device according to claim 1, wherein a lead ratio of the downstream cradle roll to the coil is larger than a lead ratio of the upstream cradle roll to the coil.   The lead rate of the downstream cradle roll to the coil after the tail end of the sheet bar passes through the roughing mill provided upstream of the sheet bar winding device is the coil of the upstream cradle roll. The sheet bar winding device according to claim 1, wherein the sheet bar winding device is larger than a lead ratio.   3. The sheet bar winding device according to claim 1, wherein a lead rate of the downstream cradle roll is greater than 0% and 20% or less greater than a lead rate of the upstream cradle roll. In the sheet bar winding method for winding the sheet bar into a coil shape,
Rotate while supporting the coil with two or more cradle rolls,
A sheet bar winding method, wherein a lead rate of the downstream cradle roll with respect to the coil is larger than 0% by 20% or less than a lead rate of the upstream cradle roll with respect to the coil.   The lead rate of the downstream cradle roll with respect to the coil after the tail end of the sheet bar has passed through the roughing mill provided upstream of the sheet bar winding device, and the coil of the upstream cradle roll. The sheet bar winding method according to claim 4, wherein the sheet bar winding ratio is larger than the lead ratio. The manufacturing method of the steel plate using the sheet bar winding method of Claim 4 or 5 .

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