JP5910541B2 - Cold rolling equipment and cold rolling method - Google Patents

Description

  The present invention relates to a cold rolling facility and a cold rolling method.

  In a general cold rolling facility, a load applied to a material to be rolled from a rolling mill is detected, and a gap of a work roll of the rolling mill is adjusted based on the detected load.

  Continuous cold rolling equipment is supplied with a continuous material to be rolled in which a preceding cold-rolled steel strip and a subsequent cold-rolled steel strip are sequentially welded to perform continuous rolling. In the welded portion of the preceding cold rolled steel strip and the subsequent cold rolled steel strip, notches are formed by cutting off both ends of the welded portion in order to remove incompletely welded portions. Before and after the notch, the sheet thickness, sheet width, and material change, so rolling control is difficult. For this reason, an off gauge on the minus side of the thickness may be locally generated at the notch portion. If the sheet thickness is negative even locally, troubles in narrowing the sheet width, breakage due to over tension, etc. will occur, impeding stable operation.

  In Patent Document 1, in a tandem cold rolling mill, a target tension value when an abnormal part such as poor welding of a material to be rolled, fogging, ear cutting, and ear cracking passes, is set to 75 to 75 of the tension during steady rolling. It is disclosed to reduce to the 95% range.

  In Patent Literature 2, the tension control between the i-th rolling stand and the (i-1) -th rolling stand is substantially performed immediately before the welded portion in which the notch is formed bites into the i-th rolling stand. Is disclosed.

JP 59-33005 A JP 2004-9116 A

  However, in the rolling control disclosed in Patent Documents 1 and 2, uniform control is performed such that tension control is reduced or not performed in the welded portion, and rolling control corresponding to each of the notches is not performed. . Therefore, depending on the shape of the notch, a negative off gauge may still occur instantaneously in the thickness of the welded portion. If off-gauge is generated in the material to be rolled, it may cause a biting trouble in a subsequent rolling mill or the like, breakage due to over tension, and the like, and stable operation cannot be performed.

  The present invention has been made for such problems, and cold rolling equipment and cold rolling capable of stably rolling the welded portion of the preceding cold rolled steel strip and the subsequent cold rolled steel strip. It aims to provide a method.

In order to achieve the above object, the cold rolling equipment and the cold rolling method according to the present invention have the following characteristics.
[1] A continuous cold rolling facility for rolling a material to be rolled having a notch formed in a welded portion to which a preceding cold rolled steel strip and a subsequent cold rolled steel strip are connected,
A cold rolling facility characterized in that a gap of a work roll of a rolling mill is set according to the shape of the notch.
[2] The cold rolling equipment according to [1], wherein the shape of the change in the gap with time is a shape reflecting the outer shape of the notch of the material to be rolled.
[3] A cold rolling method for rolling a material to be rolled having a notch formed in a welded portion where a preceding cold rolled steel strip and a subsequent cold rolled steel strip are connected,
A cold rolling method characterized in that a gap of a work roll of a rolling mill is set according to the shape of the notch.
[4] The cold rolling method according to [3], wherein the shape of the change in the gap with time is a shape reflecting the outer shape of the notch of the material to be rolled.

  According to the present invention, it is possible to provide a cold rolling facility and a cold rolling method for stably rolling a welded portion of a preceding cold rolled steel strip and a subsequent cold rolled steel strip.

It is a figure which shows the relationship between the shape of the notch of the to-be-rolled material which concerns on Embodiment 1 of this invention, and the additional gap of the work roll of a rolling mill. It is a figure which shows the relationship between the shape of the notch of the to-be-rolled material which concerns on Embodiment 2 of this invention, and the additional gap of the work roll of a rolling mill. It is a figure which shows the relationship between the shape of the notch of the to-be-rolled material rolled by the cold rolling equipment, and the additional gap of the work roll of a rolling mill in a prior art example and this invention example.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 is a diagram showing a relationship between a shape of a notch of a material to be rolled according to Embodiment 1 of the present invention and an additional gap of a work roll of a rolling mill.

  The material to be rolled is a continuous material in which the preceding cold-rolled steel strip 11 and the subsequent cold-rolled steel strip 12 are sequentially joined by welding. In the upper diagram of FIG. 1, the welded portion 14 of the preceding cold rolled steel strip 11 and the subsequent cold rolled steel strip 12 is shown. In the welded portion 14 of the preceding cold-rolled steel strip 11 and the subsequent cold-rolled steel strip 12, a notch 15 is formed by removing both ends of the plate width in order to remove incompletely welded portions.

  The notch 15 is formed by cutting both ends of the material to be rolled into the same shape. In the first embodiment, the shape of the chipped portion at both ends of the plate width is a trapezoid.

  Further, a tracking hole 13 for indicating the position of the welded portion 14 is formed in the welded portion 14.

  The cold rolling equipment is provided with a control device (not shown) for setting a target gap for a work roll of a rolling mill. In the control device, the working roll gap of the rolling mill is set in accordance with the preceding cold-rolled steel strip 11 and the subsequent cold-rolled steel strip 12 as products. Here, the gap at the time of rolling the welded portion 14 in the present invention is an additional gap corresponding to the shape of the notch 15 in addition to the gap set in the preceding cold-rolled steel strip 11 or the subsequent cold-rolled steel strip 12. Is set to the added value. Thereby, in this invention, the shape of the time change of the gap to set is made into the shape reflecting the external shape of the notch of a to-be-rolled material.

  The lower part of FIG. 1 shows an additional gap given to the working roll. As shown in the lower diagram of FIG. 1, the temporal change in the absolute value of the additional gap reflects the shape of the notch 15. Specifically, if the shape of the notch 15 is a trapezoid, the temporal change of the additional gap is set to a trapezoid.

  That is, while the sheet width of the material to be rolled decreases linearly from the sheet width of the preceding cold-rolled steel strip 11 to the minimum sheet width of the welded portion 14 at the notch 15 (from time t1 to t2), the lower diagram of FIG. As shown, the gap is increased linearly.

  And while the plate | board width of a to-be-rolled material is constant in the notch 15 (from the time t2 to t3), as shown to the lower figure of FIG. 1, a gap is kept with a constant value.

  Then, as shown in the upper diagram of FIG. 1, while the plate width of the material to be rolled increases linearly from the minimum plate width of the welded portion 14 to the plate width of the subsequent cold-rolled steel strip 12 (from time t3). (until t4), the gap is gradually narrowed.

  In addition, when controlling a gap based on the shape of the notch 15, it can comprise so that the plate width of the welding part 14 may be acquired previously as a function, and this function may be input into the control apparatus of a rolling mill. Further, the shape of the notch 15 is actually measured at the front stage of the rolling mill, and the measured data and the function of the plate width of the welded portion 14 based on the measured data are input to the control device of the rolling mill. Also good.

  In addition, although a rolling mill is normally comprised by the 6-7 rolling stand, the tracking accuracy of the welding part 14 is high in the 1st stand installed in the most entrance side. In addition, the first stand has a large rolling amount, and there is a high possibility that a negative gauge of the plate thickness is generated in the welded portion. Therefore, it is preferable to apply the gap control as described above to the first stand.

  In the cold rolling equipment and the cold rolling method according to the first embodiment configured as described above, in order to widen the gap of the work roll in accordance with the shape of the notch 15, the load applied per unit area of the welded portion 14 is increased. Change can be controlled appropriately. Thereby, it can prevent that an excessive load is added to the welding part 14 with a small board width, and can reduce generation | occurrence | production and the fracture | rupture of the welding part 14. FIG. Thereby, the cold rolling facility can be stably operated.

  In addition, the gap adjusted according to the shape of the notch 15 does not necessarily need to match the notch shape. For example, if the shape of the notch 15 is a trapezoid, the time change of the gap may be a shape obtained by enlarging or reducing the trapezoid.

  In the present invention, the gap may be set according to the shape of the notch 15, and the actual gap need not be the shape of the notch 15.

  In the present invention, the roll gap may be controlled based on the shape of the notch 15. For example, a value obtained by k-folding (0 <k), a differential or integrated value of the fluctuation of the plate width of the welded portion 14, Alternatively, the roll gap may be controlled by a combination thereof.

  Moreover, what is necessary is just to comprise so that an additional gap may be taken large, when controlling the plate | board thickness of the welding part 14 to an excessive thickness side. Thus, by controlling the plate thickness of the welded portion 14 to the over-thickness side, the occurrence rate of breakage in the welded portion 14 can be further reduced.

  The gap control as described above can be used in combination with other controls. For example, in the rolling mill, the tension of the steel sheet and the load applied to the steel sheet are controlled by adjusting the number of rotations of the work roll, the bending force of the work roll bender, and the like. These controls can be implemented in combination with these controls.

As described above, according to the present invention, as in the first embodiment, the load applied to the welded portion 14 is adjusted by adjusting the gap of the work roll according to the notch shape, and the plate thickness of the welded portion 14 is controlled. be able to.
[Embodiment 2]
Next, a cold rolling facility and a cold rolling method according to Embodiment 2 of the present invention will be described. FIG. 2 is a diagram showing a relationship between the shape of a material to be rolled by the cold rolling facility according to Embodiment 2 of the present invention and an additional gap of a work roll of a rolling mill of the cold rolling facility. In the second embodiment, the shape of the notch 15 (the shape of the cut-out defect portion) is a round shape like a semicircle.

  As shown in FIG. 2, the vertex of the semicircle is the minimum plate width of the welded portion 14. In the second embodiment, similarly to the first embodiment, control is performed to widen the gap of the work rolls according to the shape of the notch 15. The difference between the first embodiment and the second embodiment is that the notch shape is different.

  In the second embodiment, as in the first embodiment, the temporal change in the absolute value of the additional gap reflects the shape of the notch 15. That is, in Embodiment 2, since the notch shape is a round shape (semicircle), the temporal change in the absolute value of the additional gap is a round shape (semicircle).

  For the material to be rolled in which such a round notch 15 is formed, as shown in the lower diagram of FIG. 2, the material to be rolled is from the plate width of the preceding cold rolled steel strip 11 to the minimum plate of the welded portion 14. While gradually decreasing to the width (from time t1 to time t2), the additional gap is gradually increased from the target work roll gap.

  And while the plate width of the material to be rolled increases from the minimum plate width of the welded portion 14 to the subsequent cold-rolled steel strip 12 (from time t2 to t3), an additional gap is determined from the target work roll gap. Reduce.

  Thus, even if it is a to-be-rolled material in which the circular notch was formed, the load added to the welding part 14 can be appropriately controlled by applying this invention.

  The present invention is not limited to the trapezoidal or circular notch shape described above, and it is needless to say that the load can be controlled according to various notch shapes.

  An evaluation experiment of the present invention was performed using the present invention example and a conventional comparative example. In the evaluation experiment, 150 steel sheets having a thickness of 0.9 mm were prepared as cold-rolled steel strips, and the 150 cold-rolled steel strips were welded to form a continuous material to be rolled. The material to be rolled was rolled, and the breaking rate generated at that time was calculated. The fracture rate was a value obtained by dividing the number of welds where fracture occurred by the number of all welds.

  FIG. 3A shows the notch shape of the material to be rolled that is rolled by the cold rolling equipment in the present invention example and the conventional example. Moreover, FIG.3 (b) is a figure which shows the gap of the work roll of the rolling mill of the cold rolling equipment in the conventional comparative example. Moreover, FIG.3 (c) is a figure which shows the gap of the work roll of the rolling mill of the cold rolling equipment in the example of this invention to which this Embodiment 1 is applied. Also, the upper dotted line shown in FIGS. 3B and 3C indicates the allowable upper limit value of the plate thickness, and the upper dotted line indicates the allowable lower limit value of the plate thickness.

  As shown in FIG. 3A, the shape of the material to be rolled is the same as that of the first embodiment, and the notch is formed in a trapezoidal shape.

  In the comparative example shown in FIG. 3B, the sheet thickness control of the material to be rolled is performed using BISRA-AGC, and the operation with the additional gap is not performed on the welded portion. In the comparative example, after the plate thickness is reduced at the welded portion and the load is reduced, the reduction of the load is detected and control is performed to widen the gap of the work roll. For this reason, in the comparative example, the adjustment to widen the gap of the work rolls is not in time, the plate thickness is reduced at the welded portion, and an off gauge on the negative side of the plate thickness is generated at the welded portion. In the comparative example, when the off-gauge of the welded portion is detected, the gap is widened and the load is lowered. Therefore, the gap is too wide at the position of the subsequent cold-rolled steel strip following the welded portion, and the plate thickness is thick. As a result, an off-gauge on the over-thickness side occurs.

  On the other hand, in the example of the present invention (solid line) shown in FIG. 3C, an additional gap is given according to the notch shape. Therefore, the plate thickness of the material to be rolled in the present invention example does not decrease in the welded portion, and a desired plate thickness (solid line) can be secured also in the welded portion.

  In addition, what is necessary is just to take an additional gap large as shown in the dotted line of the upper figure of FIG.3 (c), when adjusting a plate | board thickness to an excessive thickness side in a welding part. Thereby, the load applied per unit width of the gap portion is reduced, and the plate thickness can be adjusted to the over-thickness side as shown by the dotted line in the lower diagram of FIG.

  As a result of the evaluation experiment, in the comparative example shown in FIG. 3B, the fracture rate of the welded part was 1%, whereas in the example of the present invention shown in FIG. %. From the above, it was found that the breaking rate can be reduced by applying the present invention.

11 Subsequent cold-rolled steel strip 12 Preliminary cold-rolled steel strip 13 Tracking hole 14 Welded portion 15 Notch

Claims (6)

A continuous cold rolling facility for rolling a material to be rolled in which a notch is formed in a welded portion where a preceding cold rolled steel strip and a subsequent cold rolled steel strip are connected,
While the plate width of the material to be rolled decreases from the plate width of the preceding cold-rolled steel strip to the minimum plate width of the weld according to the shape of the notch, the gap of the work roll of the rolling mill is increased,
While the plate width of the material to be rolled is constant according to the shape of the notch, the gap of the work roll of the rolling mill is kept constant,
While the plate width of the material to be rolled increases from the minimum plate width of the weld zone to the plate width of the subsequent cold-rolled steel strip according to the shape of the notch, the rolling mill should reduce the work roll gap of the rolling mill. cold rolling equipment characterized by comprising a control device to set the gap of the work rolls. The controller is configured such that the horizontal axis represents time and the vertical axis represents the absolute value of the gap, and the shape of the graph depicting the temporal change of the absolute value of the gap reflects the outer shape of the notch of the material to be rolled. The cold rolling equipment according to claim 1, wherein a gap of the work roll is set so as to be . The cold rolling equipment according to claim 2, wherein the control device sets a work roll gap so that the shape of the graph matches the shape of the notch of the material to be rolled. A cold rolling method for rolling a material to be rolled having a notch formed in a welded portion where a preceding cold rolled steel strip and a subsequent cold rolled steel strip are connected,
While the plate width of the material to be rolled decreases from the plate width of the preceding cold-rolled steel strip to the minimum plate width of the weld according to the shape of the notch, the gap of the work roll of the rolling mill is increased,
While the plate width of the material to be rolled is constant according to the shape of the notch, the gap of the work roll of the rolling mill is kept constant,
While the plate width of the material to be rolled increases from the minimum plate width of the weld zone to the plate width of the subsequent cold-rolled steel strip according to the shape of the notch, the rolling mill should reduce the work roll gap of the rolling mill. cold rolling method, which comprises setting the gap of the work rolls. The horizontal axis as the time and absolute value of the gap of the vertical axis, so that the shape of the graph depicting temporal change in the absolute value of the gap, a shape reflecting the outer shape of the notch of the material to be rolled, the work 5. The cold rolling method according to claim 4 , wherein a roll gap is set . The cold rolling method according to claim 5, wherein a gap of the work roll is set so that a shape of the graph matches a shape of the notch of the material to be rolled.

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