JP7156557B2 - Cold rolling method, cold rolling equipment, and method for manufacturing cold rolled steel sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cold rolling method for cold rolling a material to be rolled, cold rolling equipment, and a method for manufacturing a cold rolled steel sheet.

In a cold-rolled steel sheet production line, sheet breakage may occur due to various factors during cold-rolling of a material to be rolled. One of the reasons for this strip breakage is that the strip thickness distribution in the width direction of the material to be rolled (e.g., edge drop) increases the tension applied to the edge portion, causing a crack that occurs, causing edge cracking and strip breakage. This is the case when it reaches In order to reduce such plate breakage, it is important to suppress the generation of cracks and not enlarge the generated cracks. Edge drop refers to a phenomenon of rapid thickness reduction especially at both ends in the width direction of the thickness deviation in the width direction that occurs in a steel plate during rolling.

Conventionally, a width direction plate thickness control method for a plate disclosed in Patent Document 1, for example, has been proposed as a method for reducing the edge drop amount and improving the plate thickness distribution in the plate width direction.
In the method for controlling the thickness in the width direction of a plate material disclosed in Patent Document 1, the thickness in the width direction of a plate material is controlled by a rolling mill having a plurality of stands equipped with a mechanism for shifting and crossing work rolls having tapered roll ends. control.
According to the method for controlling thickness in the width direction of a plate material disclosed in Patent Document 1, it is possible to accurately share the control among a plurality of stands, and to adjust the width from a moderate thickness deviation that occurs from the center of the plate width toward the end side of the plate. A good thickness distribution can be obtained over the entire width of the strip, up to the thickness deviation (edge drop) that suddenly occurs at the edge.

JP-A-10-29010

However, the method for controlling the plate thickness in the width direction disclosed in Patent Document 1 has the following problems.
That is, in the method for controlling the thickness in the width direction of a plate material shown in Patent Document 1, although a good thickness distribution is obtained over the entire width of the plate, according to the tests of the present inventors, during cold rolling It was found that the generation of edge cracks in the material to be rolled could not be sufficiently suppressed, and strip breakage during cold rolling could not be sufficiently suppressed.

Therefore, the present invention has been made to solve this conventional problem, and the object thereof is to sufficiently suppress the occurrence of edge cracks in a material to be rolled during cold rolling, thereby suppressing strip breakage. It is to provide a cold rolling method, a cold rolling facility, and a method for manufacturing a cold rolled steel sheet that can

To achieve the above object, a cold rolling method according to one aspect of the present invention is a cold rolling method for cold rolling a material to be rolled using a rolling mill provided with a plurality of stands, Among them, the N-th stand arranged at the N-th (N is a natural number of 2 or more) from the upstream side in the conveying direction of the material to be rolled has a tapered work roll having a tapered end at the end of the roll with a uniform diameter. The gist is that the Nth stand rolls the rolling target material with a linear load of 0.8 t/mm or more.

A cold rolling method according to another aspect of the present invention is a cold rolling method for cold rolling a material to be rolled by a rolling mill provided with a plurality of stands, The N-th stand (N is a natural number of 2 or more) from the upstream side in the material conveying direction and the N+1-th stand downstream of the N-th stand are rolls with a uniform diameter. It has a tapered work roll with a taper formed at the end, and the Nth stand and the N+1th stand each have a linear load of 1.7 t / mm or more, and the Nth stand and the N+1th stand The taper rolling portion width WRδ, which is the length of the taper formed on each of the taper work rolls facing the rolling target material, is set to between -50 mm and -5 mm, and the rolling target material is rolled. and

In addition, a cold rolling facility according to another aspect of the present invention is a cold rolling facility comprising a rolling mill having a plurality of stands for cold rolling a material to be rolled, wherein: The N-th stand (N is a natural number of 2 or more) arranged from the upstream side in the conveying direction of the material to be rolled has a tapered work roll having a tapered end portion of a roll with a uniform diameter. The gist is that the line load of the Nth stand is set to 0.8 t/mm or more.

Further, a cold rolling facility according to another aspect of the present invention is a cold rolling facility that rolls a material to be rolled and includes a rolling mill having a plurality of stands, wherein among the plurality of stands, the rolling The N-th stand (N is a natural number equal to or greater than 2) from the upstream side in the conveying direction of the target material and the N+1-th stand downstream of the N-th stand have uniform diameters. It has a tapered work roll in which a taper is formed at the end of the roll, and the line loads of the Nth stand and the N+1 stand are each set to 1.7 t / mm or more, and the Nth stand and the The gist is that the taper rolling portion width WRδ, which is the length of the taper formed on each of the taper work rolls of the N+1 stand facing the rolling target material, is between −50 mm and −5 mm.

A method of manufacturing a cold-rolled steel sheet according to another aspect of the present invention is summarized in manufacturing a cold-rolled steel sheet by cold-rolling a steel sheet by the cold-rolling method described above.

According to the cold rolling method, the cold rolling equipment, and the method for manufacturing a cold-rolled steel sheet according to the present invention, it is possible to suppress sheet breakage by sufficiently suppressing the occurrence of edge cracks in the material to be rolled during cold rolling. can be done.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the cold-rolling equipment which concerns on 1st Embodiment of this invention. It is a figure in order to demonstrate the taper work roll in the cold-rolling equipment shown in FIG. FIG. 4 is a diagram for explaining an edge drop ratio; FIG. It is a figure for demonstrating edge-up. When the work rolls of the second stand are tapered work rolls and the work rolls of the first stand, the third stand, and the fourth stand are flat work rolls, each stand rolls the steel plate with a linear load of 1.4 t / mm. 10 is a graph showing the edge drop ratio at each stand when 4 is a graph showing the strip crown on the delivery side of each of the second stand and the third stand when the work rolls of the second stand and the third stand are flat work rolls. 5 is a graph showing the tension on the delivery side of each of the second stand and the third stand when the work rolls of the second stand and the third stand are flat work rolls. FIG. 10 is a graph showing the strip crown at the delivery side of each of the second and third stands when the work rolls of the second stand are tapered work rolls and the work rolls of the third stand are flat work rolls; FIG. 5 is a graph showing the tension at the delivery side of each of the second and third stands when the work roll of the second stand is a tapered work roll and the work roll of the third stand is a flat work roll. Breakage rate when the work roll of the second stand is a tapered work roll and the work roll of the third stand is a flat work roll, and the occurrence of breakage when the work rolls of the second and third stands are flat work rolls It is a graph showing a comparison of rates. When the work rolls of the second stand are tapered work rolls and the work rolls of the first stand, the third stand, and the fourth stand are flat work rolls, the tapered rolling portion width WRδ of the tapered work rolls of the second stand is +20 mm. , +50 mm, −5 mm, and +60 mm, and compares the edge drop ratios in each stand when rolling a steel plate with a linear load of 1.25 t/mm. When the work rolls of the second stand are tapered work rolls and the work rolls of the first stand, the third stand, and the fourth stand are flat work rolls, the tapered rolling portion width WRδ of the tapered work rolls of the second stand is +20 mm. , +50 mm, −5 mm, and +60 mm, and compares the edge drop ratios in each stand when rolling a steel plate with a line load of 1.35 t/mm. When the work rolls of the second stand are tapered work rolls and the work rolls of the first, third, and fourth stands are flat work rolls, the tapered rolling portion width WRδ of the tapered work rolls of the second stand is − 10 is a graph comparing edge drop ratios at each stand when rolling a steel plate with a linear load of 1.45 t/mm at each stand, which is changed to 20 mm, −50 mm, +5 mm, and −60 mm. When the work rolls of the second stand are tapered work rolls and the work rolls of the first, third, and fourth stands are flat work rolls, the tapered rolling portion width WRδ of the tapered work rolls of the second stand is − FIG. 10 is a graph comparing the edge drop ratios at each stand when rolling a steel plate with a linear load of 1.60 t/mm at each stand, which is changed to 20 mm, −50 mm, +5 mm, and −60 mm. It is a schematic block diagram of the cold-rolling equipment which concerns on 2nd Embodiment of this invention. When all the work rolls of the 1st to 4th stands are flat work rolls, when only the work rolls of the 2nd stand are tapered work rolls, and when the work rolls of the other stands are flat work rolls, and When the work rolls of the 2nd stand and the 3rd stand are tapered work rolls and the work rolls of the other stands are flat work rolls, each stand rolls the steel material with a line load of 1.7 t / m. 10 is a graph showing edge drop ratios in the stand;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below exemplify apparatuses and methods for embodying the technical idea of the present invention. It is not intended to be specific to the following embodiments. Also, the drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between the thickness and the planar dimensions are different from the actual ones, and the drawings include portions where the relationship and ratio of the dimensions are different from each other.

(First embodiment)
FIG. 1 shows a schematic configuration of a cold rolling facility according to a first embodiment of the present invention.
The cold rolling facility 1 shown in FIG. 1 includes a rolling mill (tandem rolling mill) 2 having a plurality of (four in this embodiment) stands 3 ₁ to 3 ₄ . The rolling mill 2 cold-rolls a steel plate S (see FIG. 2) as a material to be rolled. A steel sheet S is rolled by a rolling mill 2 while being conveyed from the upstream side to the downstream side of a cold rolling facility 1 . The stands are a first stand 3 _{1 that is first from the upstream side in the conveying direction of the steel plate S, a second stand 3 2 that is arranged downstream of the first stand 3 1 , and} a downstream side of the second stand 3 ₂ . It consists of a third stand 3 ₃ and a fourth stand 3 ₄ located downstream of the third stand 3 ₃ . The number of stands is not limited to four, and may be any number. The subscript of each stand indicates the arrangement order from the upstream side in the conveying direction of the steel plate S, and the N-th stand (N is a natural number of 2 or more) from the upstream side in the conveying direction of the steel plate S is the Nth stand 3 The stands arranged at _N 1 and N+1 are called N+1-th stands 3 _N+1 , . . . . In FIG. 1, for reference, the second stand 3 ₂ is parenthesized as the Nth stand 3 _N , and the third stand 3 ₃ is parenthesized as the N+1th stand 3 _N+1 .

Each of the first stand 3 ₁ to fourth stand 3 ₄ includes a pair of upper and lower work rolls 4a for rolling a steel plate S as a material to be rolled, a pair of upper and lower backup rolls 4b for supporting these work rolls 4a, and each work. A pair of upper and lower intermediate rolls 4c are provided between the roll 4a and each backup roll 4b.
Each work roll 4a of the _second stand 3 ₂ is composed of a tapered work roll 4a1 (hatched in FIG. 1), and the first stand 3 ₁ , third stand 3 ₃ , and each work roll 4a of the _fourth stand 34 is composed of a flat work roll 4a2 (not hatched in FIG. 1). The configurations of the tapered work roll 4a1 and the flat work roll 4a2 will be described later.
The reason why each work roll 4a of the _second stand 32 is composed of the tapered work roll 4a1 will be described below.

The inventors cold-rolled an electrical steel sheet as a material to be rolled by a rolling mill (tandem rolling mill) 2 having four first stands 3 ₁ to a fourth stand 3 ₄ as shown in FIG. We investigated a stand that causes edge splitting and breakage. In the rolling mill 2 used in this test, among the four first stands 3 _{1 to 4 4, the work rolls 4a of the first stand 3 1 and the fourth stand 3 4 are tapered} work rolls 4a1, and the second The work roll 4a of the stand _3-2 and the _third stand 3-3 was used as a flat work roll 4a2.

As a result of investigating the origin of cracks by rolling the electromagnetic steel sheet with the rolling mill 2, it was confirmed that edge cracks occurred on the delivery side of the _third stand 33. In order to identify the cause, the edge drop ratio in each of the first stand 3 ₁ to the fourth stand 3 ₄ was investigated.
The term "edge drop" as used herein refers to a rapid thickness reduction phenomenon, particularly at both ends in the width direction, of the thickness deviation in the width direction that occurs in the steel sheet S being rolled. The edge drop ratio is, as shown in FIG. is represented by
Edge drop ratio Ed=(E5-E20)/E20

Note that edge-up, which is known as a plate thickness deviation in contrast to edge drop, refers to a phenomenon of a rapid increase in plate thickness, especially at both ends in the width direction, among the plate thickness deviations in the width direction that occur in the steel plate S during rolling. It is said. As shown in FIG. 4, the edge-up amount is given by the following equation, where E5 is the plate thickness at 5 mm from both end faces in the plate width direction of the steel plate S, and E20 is the plate thickness at 20 mm from the both end faces. expressed.
Edge-up amount Eu=E5-E20
3 and 4, symbol CL indicates the center line of the steel plate S in the width direction.

As a result of investigating the edge drop ratio at each of the first stand 3 ₁ to the fourth stand 3 ₄ , the edge drop ratio at the third stand 3 ₃ greatly increased and exceeded the appropriate range, and then the edge drop ratio at the fourth stand 3 ₄ I found the drop rate to be low. Here, an increase in the edge drop ratio means that the numerical value of the edge drop ratio increases on the negative side, and a decrease in the edge drop ratio means that the numerical value of the edge drop ratio decreases on the negative side.
That is, if the difference between the edge drop ratio at the _fourth stand 34 and the edge drop ratio at the _third stand 34 is large (the difference is 0.02 or more on the + side), plate breakage is likely to occur. I found out.

This is because excessive tension is applied to both edges in the width direction of the electromagnetic steel sheet in the _third stand ₃₃ , and cracks at the edges occur in the _second stand 32 on the upstream side. It is presumed that the ear crack occurred on the exit side of the
For this reason, the present inventors used the work roll 4a of the _second stand 32 on the upstream side as a tapered work roll 4a1 to make the thickness distribution of the steel plate uniform, and the work roll 4a of the _third stand 33 on the downstream side. It is referred to as a flatwork roll 4a2. As a result, the edge drop ratio at the first stand 3 ₁ , the second stand 3 ₂ , the third stand 3 ₃ , and the fourth stand 3 ₄ can be within the appropriate range, and the edge drop ratio at the fourth stand 3 ₄ can be kept within the appropriate range. The difference between the drop ratio and the edge drop ratio at the _third stand 333 becomes smaller, the tension applied to the edge portion at the downstream _third stand 333 is reduced, and edge cracking of the steel plate can be suppressed. I got the knowledge that

Therefore, each work roll 4a of the _second stand 32 is composed of a tapered work roll 4a1. As a result, rolling with the tapered work rolls 4a1 in the _second stand 32 suppresses the occurrence of excessive edge drop, and even if rolling is performed with the flat work rolls in the _third stand 33 after that, the edge portion It has been found that the applied tension is reduced and the occurrence of cracks is suppressed. As a result of cold-rolling an electromagnetic steel sheet as a material to be rolled by the rolling mill 2 shown in FIG.

In FIG. 5, the work roll 4a of the _second stand 32 is a tapered work roll 4a1 (the width WRδ of the tapered rolling part of the _second stand 32 is set between -50 mm and -5 mm), and other When the work rolls 4a of the stands 3 ₁ , 3 ₃ , and 3 ₄ are flat work rolls 4a2, each of the first stand 3 ₁ to the fourth stand 3 ₄ rolls the steel sheet S with a linear load of 1.4 t/mm. The edge drop ratios in each of the first stand 3 ₁ to the fourth stand 3 ₄ are shown. As shown in FIG. 5, when the tapered work roll 4a1 is applied to the second stand 3 ₂ , the edge drop ratio does not increase greatly from the first stand 3 ₁ to the fourth stand 3 ₄ , and is within an appropriate range. , and the difference between the edge drop ratio at the _fourth stand 34 and the edge drop ratio at the _third stand 34 was found to be less than 0.02.

FIG. 6 shows the plate crown at the delivery side of each of the _second stand _3-2 and the _third stand 3-3 when the work rolls 4a of the second stand 3-2 and the _third stand 3-3 are flat work rolls 4a2. It is shown. FIG. 7 shows the output side of each of the _second stand _3-2 and the _third stand 3-3 when the work rolls 4a of the second stand 3-2 and the _third stand 3-3 are flat work rolls 4a2. Tension is indicated.
As shown in FIG. 6, when the flatwork roll 4a2 is applied to the second stand _3-2 and the _third stand 3-3, excessive edge drop occurs in the _second stand 3-2. On the other hand, the edge drop ratio increases significantly from the _second stand 32 to the _third stand ₃₃₃ , and as shown in FIG.

In addition, FIG. 8 shows the _second stand 32 and the third stand 32 when the work roll 4a of the _second stand 32 is a tapered work roll 4a1 and the work roll 4a of the _third stand 33 is a flat work roll 4a2. The plate crown at each exit side of stand ₃₃ is shown. In addition, FIG. 9 shows the _second stand 32 and the third stand 32 when the work roll 4a of the _second stand 32 is a tapered work roll 4a1 and the work roll 4a of the _third stand 33 is a flat work roll 4a2. The tension at each exit side of stand ₃₃ is shown.

As shown in FIG. 8, when a tapered work roll 4a1 is applied to the _second stand 3-2 and a flat work roll 4a2 is applied to the _third stand 3-3, excessive edge drop occurs at the _second stand 3-2. As shown in FIG. 9, it can be seen that the edge drop is appropriately promoted at the _third stand 33 and the edge tension is prevented from becoming excessive.
Comparing the fracture occurrence rates for _each , as shown in _FIG . It was possible to reduce the rate of occurrence of breakage compared to the case of constructing.

From the above, by configuring the work roll 4a of the _second stand 32 with the tapered work roll 4a1, the occurrence of excessive edge drop in the _second stand 32 on the upstream side is suppressed, and the third stand 32 on the downstream side It was possible to reinforce the above knowledge that the stand ₃₃ can reduce the tension applied to the edge portion of the steel plate S to suppress the occurrence of edge cracks.
The above results are obtained when the _second stand 32 having the tapered work rolls 4a1 rolls the steel sheet S with a line load (rolling load/sheet width) of 1.4 t/mm.

As a result of further tests, as shown in Tables 1 and 11, Tables 2 and 12, when the line load of the _second stand 32 having the tapered work roll 4a1 is set to less than 1.4 t/mm , the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is preferably between ±0 mm and +50 mm. The tapered rolling portion width WRδ will be described in detail later, but the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is assumed to be a negative value, that is, the tapered work roll 4a1 of the _second stand 32 is set to If the steel sheet S is rolled while being shifted in the negative direction, the edge of the steel sheet S is reversely raised at the shifted _second stand 32, causing edge cracks or breakage. Here, in the case of edge cracks, the steel sheet S cannot be passed to the next process (annealing process), and there is a _high possibility that the steel sheet S will be cracked by annealing. It is preferable to roll the steel plate S by shifting to . Even if the tapered work rolls 4a1 of the _second stand 32 are shifted in the positive direction, if the tapered rolling portion width WRδ of the tapered work rolls 4a1 of the second stand 32 is larger than +50 mm, the shifted _second stand 3 Since there is a risk that the edge of the steel plate S will be raised in the _third stand 33 next to ₂ , and edge cracks or breakage may occur, the upper limit of the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set to +50 mm It is preferable to

In Table 1 and FIG. 11, the work roll 4a of the second stand 3 ₂ is a tapered work roll 4a1, the work roll 4a of the first stand 3 ₁ , the third stand 3 ₃ , and the work roll 4a of the fourth stand 3 ₄ is a flat work roll 4a2. In the case where the tapered rolling portion width WRδ of the tapered work roll 4a1 of the second stand is changed to +20 mm, +50 mm, -5 mm, and +60 mm, each stand rolls the steel plate with a line load of 1.25 t / mm. The stand edge drop ratio is shown in comparison.

As shown in Table 1 and FIG. 11, when the _second stand 32 having the tapered work rolls 4a1 rolls the steel plate S with a linear load of 1.25 t/mm, the tapered work rolls 4a1 of the _second stand 32 When the steel plate S is rolled with the taper-rolled portion width WRδ set to −5 mm outside the range, the _second stand 32 shifted in the negative direction is edged up, and the taper-rolled portion width WRδ is set to +60 mm outside the range to roll the steel plate S. , the second stand 3-3 next to the _second stand _3-2 shifted in the positive direction is edged up. When the steel sheet S is rolled with the taper-rolled portion width WR δ within the range of +20 mm and +50 mm, the edge drop is appropriately promoted in the second stand 3 ₂ , the third stand 3 ₃ , and the fourth stand 3 ₄ . I understand.

In addition, in Table 2 and FIG. 12, the work roll 4a of the second stand 3 ₂ is a tapered work roll 4a1, the work roll 4a of the first stand 3 ₁ , the third stand 3 ₃ , and the work roll 4a of the fourth stand 3 ₄ is a flat work. When the roll 4a2 is used, the width WRδ of the tapered rolling portion of the tapered work roll 4a1 of the second stand is changed to +20 mm, +50 mm, -5 mm, and +60 mm, and each stand rolls the steel plate with a linear load of 1.35 t / mm. is shown by comparing the edge drop ratio at each stand.

As shown in Table 2 and FIG. 12, when the _second stand 32 having the tapered work rolls 4a1 rolls the steel sheet S with a linear load of 1.35 t/mm, the tapered work rolls 4a1 of the _second stand 32 When the steel plate S is rolled with the taper-rolled portion width WRδ set to −5 mm outside the range, the edge is raised by the _second stand 32 shifted in the negative direction, and the taper-rolled portion width WRδ is set to +60 mm outside the range to roll the steel plate S. , the edge is raised at the second stand _3-3 next to the _second stand 3-2 shifted in the positive direction. When the steel plate S is rolled with the taper rolling portion width WR δ within the range of +20 mm and +50 mm, it can be seen that the edge drop is appropriately performed on the second stand 3 ₂ , the third stand 3 ₃ , and the fourth stand 3 ₄ . .

The lower limit of the line load at which edge cracks occur in the steel sheet S unless the _second stand 32 is shifted in the positive direction is 0.8 t/mm. In other words, when the steel sheet S is rolled with a line load of less than 0.8 t/mm, edge cracks do not occur in the steel sheet S regardless of the shift direction of the _second stand 32 .

Further, as a result of further tests, as shown in Tables 3 and 13, Tables 4 and 14, when the line load of the _second stand 32 having the tapered work roll 4a1 is set to 1.4 t/mm or more , it was found that it is preferable to set the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 to between -50 mm and -5 mm. When the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is set to a positive value, that is, when the tapered work roll 4a1 of the _second stand 32 is shifted in the positive direction to roll the steel sheet S, the shifted The edge of the steel plate S rises at the next stand (the third stand 3 3 ) after the second stand 3 ₂ (the third stand 3 ₃ ) or at the next stand (the fourth stand 3 ₄ ), and edge cracks or breaks occur. The above-mentioned ``it was found that if the difference between the edge drop ratio at the fourth stand _3-4 and the edge drop ratio at the _third stand 3-3 is large, it was found that the plate breakage is likely to occur'' The edge of the steel plate S rises at the stand next to the second stand 3 ₂ (fourth stand 3 ₄ ), and edge cracking or breakage occurs”. Here, in the case of edge cracks, the steel sheet S cannot be passed to the next process (annealing process), and there is a high possibility that the steel sheet S will crack during annealing. In addition, if the tapered work roll 4a1 of the _second stand 32 is shifted in the positive direction to roll the steel sheet S, the shifted _second stand 32 produces too much edge drop (excessive edge drop occurs), so The stand (third stand 3 ₃ ) cannot roll down the edge of the steel plate S, and the increased tension causes edge cracking. Therefore, it is preferable to roll the steel plate S while shifting the _second stand 32 in the negative direction. Even if the _second stand 32 is shifted in the negative direction, if the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is made larger _than −50 mm, the steel sheet S is Since there is a risk that edge cracks or breakage may occur due to edge-up, the lower limit of the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is preferably −50 mm.

In Table 3 and FIG. 13, the work roll 4a of the second stand 3 ₂ is a tapered work roll 4a1, the work roll 4a of the first stand 3 ₁ , the third stand 3 ₃ , and the work roll 4a of the fourth stand 3 ₄ is a flat work roll 4a2. In the case where the tapered rolling portion width WRδ of the tapered work roll 4a1 of the second stand is changed to -20 mm, -50 mm, +5 mm, and -60 mm, each stand rolls the steel plate with a line load of 1.45 t / mm is shown by comparing the edge drop ratio at each stand.

As shown in Table 3 and FIG. 13, when the second stand 32 having the tapered work rolls 4a1 rolls the steel plate S with a linear load of 1.45 t/mm, the tapered rolling portion width _WRδ of the _second stand 32 When the steel plate S is rolled with +5 mm outside the range, excessive edge drop occurs in the _second stand 32 shifted in the positive direction, the edge is raised in the next _third stand 32, and the width of the tapered rolled part It can be seen that when the steel sheet S is rolled with WR δ set to −60 mm, which is outside the range, the edge is raised by the _second stand 32 shifted in the negative direction. When the steel plate S is rolled with the taper-rolled portion width WR δ within the range of −20 mm and −50 mm, the edge drop is appropriately promoted in the second stand 3 ₂ , the third stand 3 ₃ , and the fourth stand 3 ₄ . I know there is.

In addition, in Table 4 and FIG. 14, the work roll 4a of the second stand 3 ₂ is a tapered work roll 4 a 1, the work roll 4 a of the first stand 3 ₁ , the third stand 3 ₃ , and the work roll 4 a of the fourth stand 3 ₄ is a flat work. When the roll 4a2 is used, the tapered rolling portion width WRδ of the tapered work roll 4a1 of the second stand is changed to −20 mm, −50 mm, +5 mm, and −60 mm, and each stand rolls the steel plate with a linear load of 1.60 t / mm. The figure shows a comparison of the edge drop ratio at each stand when

As shown in Table 4 and FIG. 14, when the _second stand 32 having the tapered work rolls 4a1 rolls the steel sheet S with a linear load of 1.60 t/mm, the tapered work rolls 4a1 of the _second stand 32 When the steel plate S is rolled with the taper rolling portion width WRδ set to +5 mm outside the range, excessive edge drop occurs in the _second stand 32 shifted in the positive direction, and the edge is raised in the next _third stand 32, It can be seen that when the steel sheet S is rolled with the taper rolling portion width WRδ set to −60 mm, which is outside the range, the _second stand 32 shifted in the negative direction is edged up. When the steel plate S is rolled with the taper-rolled portion width WR δ within the range of −20 mm and −50 mm, the edge drop is appropriately promoted in the second stand 3 ₂ , the third stand 3 ₃ , and the fourth stand 3 ₄ . I know there is.

From the above, the work roll 4a of the _second stand 32 is composed of the tapered work roll 4a1, and the _second stand 32 having the tapered work roll 4a1 rolls the steel sheet S with a linear load of 0.8 t / mm or more. do. Then, when the _second stand 32 rolls the steel plate S with a linear load of less than 1.4 t / mm, the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set to between ±0 mm and +50 mm. A steel plate S is rolled. Further, when the _second stand 32 rolls the steel plate S with a linear load of 1.4 t/mm or more, the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set between -50 mm and -5 mm. The steel plate S is rolled as It was found that by this, both edge drop and edge up can be appropriately controlled, and the occurrence of edge cracks can be suppressed.

In this way, the tapered work roll 4a1 of the _second stand 32 is shifted in the positive direction or the negative direction with the linear load of the _second stand 32 having the tapered work roll 4a1 at 1.4 t/mm. The reason for deciding whether to allow That is, when the linear load of the _second stand 32 having the tapered work rolls 4a1 is set to 1.4 t/mm or more, the material to be rolled is a high-load material and the tapered work rolls 4a1 easily bend, so the tapered work Excessive edge drop is suppressed by shifting the roll 4a1 in the negative direction. On the other hand, when the linear load of the _second stand 32 having the tapered work rolls 4a1 is set to less than 1.4 t/mm, the material to be rolled is a low-load material, and the tapered work rolls 4a1 are less likely to bend and edge up. Since it is likely to occur, it is brought to the edge drop side by shifting the tapered work roll 4a1 in the positive direction.

Next, the configuration of the tapered work roll 4a1 will be described with reference to FIG. The tapered work roll 4a1 has a taper 4ab formed at the end of the roll 4aa having a uniform diameter in the trunk length direction. The work roll 4a, which is the tapered work roll 4a1, is configured to be shiftable in the axial direction (roll body length direction, steel plate S plate width direction).
The taper rolling portion width WRδ of the taper work roll 4a1 is the length of the taper 4ab facing the steel plate S, and is the length from the taper start end 4ac to the widthwise end face of the steel plate S in FIG. Then, as described above, when the _second stand 32 rolls the steel plate S with a linear load of less than 1.4 t/mm, the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is ±0 mm to The steel plate S is rolled between +50 mm. That is, it is preferable to roll the steel sheet S by shifting the tapered work rolls 4a1 of the _second stand 32 in the positive direction.

Further, as described above, when the _second stand 32 rolls the steel plate S with a linear load of 1.4 t/mm or more, the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set to −50 mm to The steel plate S is rolled between -5 mm. That is, it is preferable to roll the steel plate S by shifting the tapered work roll 4a1 of the _second stand 32 in the negative direction.
The width WRδ of the taper rolled portion is − when the widthwise end face of the steel plate S protrudes from the taper starting end 4ac, and + when the widthwise end face of the steel plate S recedes from the taper starting end 4ac. When the tapered rolling portion width WRδ is +, the same operation as when the flat work rolls 4a2 are employed is performed.

In addition, the inclination of the taper 4ab is such that L is the length from the taper start end 4ac to the taper end face (the end face in the axial direction of the tapered work roll 4a1), and the difference in height between the outer peripheral surface of the roll 4aa and the outer periphery of the taper end face. is H, it can be represented by L/H. The inclination L/H of this taper 4ab is preferably 1/800 to 1/400. If the slope L/H of the taper 4ab is smaller than 1/800, there is a problem that edge drop cannot be suppressed. On the other hand, if the inclination L/H of the taper 4ab is larger than 1/400, there is a problem that the edge is raised too much.
The flat work roll 4a2 is composed of a roll having a uniform diameter in the trunk length direction. The work roll 4a, which is the flat work roll 4a2, is configured to be shiftable in the axial direction (roll body length direction, steel plate S plate width direction).

As described above, in the cold rolling equipment 1 according to the first embodiment, among the four stands 3 ₁ to 3 ₄ , the second stand from the upstream side in the conveying direction of the steel plate S as the material to be rolled The second stand 32 arranged in the _second stand 32 has a tapered work roll 4a1 having a taper 4ab formed at the end of the roll 4aa having a uniform diameter. The linear load of the _second stand 32 is set to 0.8 t/mm or more. When the linear load of the _second stand 32 is set to less than 1.4 t/mm, the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is set between ±0 mm and +50 mm. Further, when the linear load of the _second stand 32 is set to 1.4 t/mm or more, the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set between -50 mm and -5 mm.
As a result, the edge drop ratio in the first stand 3 ₁ to the fourth stand 3 ₄ is kept within an appropriate range, and the occurrence of edge cracks in the steel plate S as the rolling target material during cold rolling is sufficiently suppressed, thereby breaking the plate. can be deterred.

In addition, in the cold rolling mill 1 according to the first embodiment, of the four first stands 3 ₁ to the fourth stand 3 ₄ , the third stand located third downstream of the second stand 3 _{2 33} has a flatwork roll 4a2 with a uniform roll diameter.
This has the effect of promoting edge drop.
In addition, in the cold rolling mill 1 according to the first embodiment, the first stand 3 ₁ arranged most upstream among the four first stands 3 ₁ to the fourth stand 3 ₄ has a flat work roll 4a2. Although it has, it may have a tapered work roll 4a1.
This has the effect of suppressing edge drops.

Further, in the cold rolling method according to the first embodiment, a steel sheet S as a material to be rolled is cold-rolled by a rolling mill 2 in a cold rolling facility 1 shown in FIG. At this time, of the four first stands 3 ₁ to 4 stand 3 ₄ , the second stand 3 ₂ arranged second from the upstream side in the conveying direction of the steel plate S is the end of the roll 4aa with a uniform diameter. The second stand 32 has tapered work rolls 4a1 with tapered portions 4ab formed therein, and the _second stand 32 rolls the steel plate S with a linear load of 0.8 t/mm or more.
When the _second stand 32 rolls the steel sheet S with a linear load of less than 1.4 t/mm, the length of the taper 4ab formed on the tapered work roll 4a1 of the _second stand 32 facing the steel sheet S is The steel plate S is rolled with the taper rolling portion width WRδ being between ±0 mm and +50 mm.

On the other hand, when the _second stand 32 rolls the steel sheet S with a linear load of 1.4 t/mm or more, the length of the taper 4ab formed on the tapered work roll 4a1 of the _second stand 32 facing the steel sheet S is The steel plate S is rolled with the taper rolling portion width WRδ set to between −50 mm and −5 mm.
As a result, the edge drop ratio in the first stand 3 ₁ to the fourth stand 3 ₄ is kept within an appropriate range, and the occurrence of edge cracks in the steel plate S as the rolling target material during cold rolling is sufficiently suppressed, thereby breaking the plate. can be deterred.
In the method for manufacturing a cold-rolled steel sheet according to the first embodiment, the steel sheet S is cold-rolled by the cold-rolling method according to the first embodiment to manufacture a cold-rolled steel sheet.

(Second embodiment)
Next, a cold rolling facility according to a second embodiment of the present invention will be described with reference to FIG. FIG. 15 shows a schematic configuration of a cold rolling facility according to a second embodiment of the present invention. In FIG. 15, the same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof may be omitted. In FIG. 15, for reference, the second stand 3 ₂ is parenthesized as the Nth stand 3 _N , the third stand 3 ₃ is parenthesized as the N+1 stand 3 _N+1 , and the fourth stand 3 ₄ is parenthesized as the No. N+2 stand 3 _N+2 is written together.

Unlike the cold rolling plant 1 shown in _FIG . 1, the cold rolling plant 1 shown in FIG. In addition, each work roll 4a of the _third stand 33 is composed of a tapered work roll 4a1. Each work roll 4a of the _first stand 3-1 and the fourth stand _3-4 is composed of a flat work roll 4a2.
The reason why the work rolls 4a of the _second stand 3.2 and the work rolls 4a of the _third stand 3.3 are composed of the tapered work rolls 4a1 will be described below.

In FIG. 16, when all the work rolls of the first stand to the fourth stand are flat work rolls, only the work roll of the second stand is a tapered work roll (taper rolling of the tapered work roll 4a1 of the _second stand 32) The part width WRδ is between -50 mm and -5 mm), and the work roll of the stand is a flat work roll, and the work rolls of the second and third stands are tapered work rolls (second The tapered rolling portion width WRδ of the tapered work roll 4a1 of the stand 32 and the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _third stand ₃₂ are set between -50 mm and -5 mm), and other stands 2 shows the edge drop ratio at each stand when the work rolls are flat work rolls and each stand rolls a steel material with a line load of 1.7 t/m.

As shown in FIG. 16, the _second stand 32 having tapered work rolls 4a1 (the tapered rolling portion width WRδ of the _second stand 32 is between -50 mm and -5 mm) has a line speed of 1.7 t/mm. In the case of rolling an electrical steel sheet with a load, the edge drop ratio does not rise significantly from the first stand 3 ₁ to the fourth stand 3 ₄ and remains within the appropriate range. The _second stand 32 having tapered work rolls 4a1 (the tapered rolling portion width WRδ of the _second stand 32 is between -50 mm and -5 mm) rolls the magnetic steel sheet with a linear load greater than 1.7 t/mm. Similar results were obtained in the case of rolling.

On the other hand, as can be seen from FIG. 16, two continuous tapered work rolls 4a1 (the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 and the tapered rolling portion of the tapered work roll 4a1 of the _third stand 33 When the second stand 3 ₂ and the third stand 3 ₃ having the width WR δ are set between −50 mm and −5 mm, rolling the electromagnetic steel sheet with a linear load of 1.7 t / mm, the second stand The rate of increase from the edge drop ratio at _3.2 to the edge drop ratio at the _third stand 3.3 can be kept smaller than when only the work roll 4a of the _second stand 32 is the tapered work roll 4a1. A similar result is obtained when the second stand _3-2 and the _third stand 3-3 having two continuous tapered work rolls 4a1 roll the electromagnetic steel sheet with a linear load greater than 1.7 t/mm.

As a result, the tension applied to the edge portion of the _third stand 33 is further reduced, and edge cracking of the steel plate can be more appropriately suppressed.
For this reason, in the cold rolling equipment 1 shown in _FIG . 4a is composed of the tapered work roll 4a1, and each work roll 4a of the _third stand 33 is composed of the tapered work roll 4a1.
However, when the linear load of the second stand 3 ₂ and the third stand 3 ₃ having the tapered work roll 4 a 1 is set to 1.7 t / mm or more, for the same reason as described in the first embodiment , the tapered rolling portion width WRδ of the tapered work rolls 4a1 of the _second stand 3.2 and the _third stand 3.2 is set between -50 mm and -5 mm.

As described above, in the cold rolling equipment 1 according to the second embodiment, among the four first stands 3 ₁ to the fourth stand 3 ₄ , the second The second stand 3 ₂ and the third stand 3 ₃ located downstream of the second stand 3 ₂ are tapered work rolls in which tapers 4 ab are formed at the ends of rolls 4 aa having a uniform diameter. has 4a1. Then, the linear load of the second stand _3-2 and the _third stand 3-3 is set to 1.7 t/mm or more, and the tapered work roll 4a1 of each of the second stand _3-2 and the _third stand 3-3 has a linear load of 1.7 t/mm or more. A taper rolled portion width WRδ, which is a length facing the steel plate S in the tapered taper 4ab, is set between −50 mm and −5 mm.
As a result, the edge drop ratio in the first stand 3 ₁ to the fourth stand 3 ₄ is kept within an appropriate range, and the occurrence of edge cracks in the steel sheet S, which is the material to be rolled during cold rolling, is sufficiently suppressed. Breakage can be suppressed.

In addition, in the cold rolling mill 1 according to the second embodiment, among the four first stand 3 ₁ to fourth stand 3 ₄ , the fourth stand located downstream of the third stand 3 _{3 34} has a flatwork roll 4a2 with a uniform roll diameter.
This has the effect of promoting edge drop.
In addition, in the cold rolling mill 1 according to the second embodiment, the first stand 3 ₁ arranged most upstream among the four first stands 3 ₁ to the fourth stand 3 ₄ has a flat work roll 4a2. Although it has, it may have a tapered work roll 4a1.
This has the effect of suppressing edge drops.

Further, in the cold rolling method according to the second embodiment, a steel sheet S as a material to be rolled is cold-rolled by a rolling mill 2 in a cold rolling facility 1 shown in FIG. At this time, the second stand 3 ₂ and the third stand 3 ₃ of the four first stand 3 ₁ to fourth stand 3 ₄ are tapered rolls 4aa having a uniform diameter and tapers 4ab formed at the ends of the rolls 4aa. It has a work roll 4a1. The second stand _3-2 and the _third stand 3-3 have a linear load of 1.7 t/mm or more and are formed on the tapered work rolls 4a1 of the second stand _3-2 and the _third stand 3-3. The steel plate S is rolled with the taper rolling portion width WRδ, which is the length of the taper 4ab facing the steel plate S, set to between −50 mm and −5 mm.
As a result, the edge drop ratios at the first stand 3 ₁ to the fourth stand 3 ₄ are kept within an appropriate range, and the generation of edge cracks in the steel sheet S, which is the material to be rolled during cold rolling, can be sufficiently suppressed. Board breakage can be suppressed.

Here, the configuration of the tapered work roll 4a1 is the same as that shown in FIG. It is The work roll 4a, which is the tapered work roll 4a1, is configured to be shiftable in the axial direction (roll body length direction, steel plate S plate width direction).
The taper rolled portion width WRδ, which is the length of the taper 4ab facing the steel plate S, is the case where the widthwise end face of the steel plate S protrudes from the taper starting end 4ac, and the widthwise end face of the steel plate S protrudes from the taper starting end 4ac. Assuming that the case of retraction is +, the steel plate S is rolled between −50 mm and −5 mm as described above. Also, the inclination L/H of the taper 4ab is preferably 1/800 to 1/400 as described above.

By the way, even the tapered work roll 4a1 can be used as the flat work roll 4a2 when the tapered rolling portion width WRδ is greater than 0 mm on the positive side.
Therefore, in both the cold rolling equipment 1 of the first embodiment and the second embodiment, the work rolls 4a of the _second stand 32 and the work rolls 4a of the _third stand 33 are tapered work rolls 4a1, Each work roll 4a can also be shifted in the axial direction according to the line load to roll in a preferred manner.
That is, when the line load is 0.8 t/mm or more and less than 1.4 t/mm, the taper rolling width WRδ in the _second stand 32 is between ±0 mm and +50 mm, and in the _third stand 32 Each work roll 4a may be shifted in the axial direction so that the tapered rolling portion width WRδ>0 mm, and the tapered work roll 4a1 may be used as the flat work roll 4a2.

Further, when the line load is 1.4 t/mm or more and less than 1.7 t/mm, the taper rolling width WRδ in the _second stand 32 is between -50 mm and -5 mm, and the taper in the _third stand 33 Each work roll 4a may be shifted in the axial direction so that the width of the rolled portion WRδ>0 mm and used as the flat work roll 4a2.
Furthermore, when the line load is 1.7 t / mm or more, each workpiece is adjusted so that the tapered rolling part width WRδ is between -50 mm and -5 mm in each of the second stand 3 ₂ and the third stand 3 ₃ The roll 4a may be axially shifted and used as a tapered work roll 4a1.
Then, in the method for manufacturing a cold-rolled steel sheet according to the second embodiment, the steel sheet S is cold-rolled by the cold-rolling method according to the second embodiment to manufacture a cold-rolled steel sheet.

Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified and improved in various ways.
In the first and second embodiments, the rolling mill (tandem rolling mill) 2 including four first stands 3 ₁ to fourth stand 3 ₄ was described as an example, but the number of stands is not limited to this. The rolling mill 2 may have five or more stands. When five or more stands are provided, when the number of stands with the work roll 4a as the tapered work roll 4a1 is one as in the first embodiment, one of the stands in the preceding stage except for the most upstream stand You should choose the stand of In addition, when the number of stands with the work roll 4a as the tapered work roll 4a1 is two consecutive as in the second embodiment, at least one of them is selected from the preceding stands except for the most upstream stand. It is sufficient if it is a single stand.

In the first embodiment, the tapered work rolls 4a1 are applied to the _second stand 32, but this is because the _third stand 33 breaks in the rolling mill 2 of the first embodiment. It was selected as its upstream stand. The tapered work roll 4a1 is applied to the second stand _3-2 and the _third stand 3-3 in the second embodiment because the _third stand 3-3 is likely to break. In the first and second embodiments, the taper work rolls 4a1 may be applied to other stands depending on the configuration of the rolling mill (tandem rolling mill) 2 or the like.

Based on the above, in the cold rolling method, the cold rolling equipment, and the method for manufacturing a cold-rolled steel sheet according to the present invention, among the plurality of stands 3 ₁ to 3 ₄ , the upstream of the conveying direction of the steel sheet S as the material to be rolled The Nth stand 3N arranged at the Nth ( _N is a natural number of 2 or more) from the side has a tapered work roll 4a1 having a taper 4ab formed at the end of the roll 4aa with a uniform diameter. Then, at the _N -th stand 3N, the steel sheet S as the material to be rolled is rolled with a linear load of 0.8 t/mm or more.
Further, when the _Nth stand 3N rolls the steel plate S with a linear load of less than 1.4 t / mm, the length of the taper 4ab formed on the tapered work roll 4a1 of the _Nth stand 3N facing the steel plate S It is preferable to roll the steel sheet S with the tapered rolled portion width WRδ, which is between ±0 mm and +50 mm.

On the other hand, when the N-th stand 3 _N rolls the steel plate S with a linear load of 1.4 t / mm or more, the length of the taper 4 ab formed on the tapered work roll 4 a1 of the N-th stand 3 _N facing the steel plate S It is preferable to roll the steel plate S with the taper rolling portion width WRδ being between −50 mm and −5 mm.
In the cold rolling method, the cold rolling equipment, and the cold rolled steel sheet manufacturing method according to the present invention, among the plurality of stands 3 ₁ to 3 ₄ , the stand is arranged at the N+1th downstream side of the _Nth stand 3N. It is preferable that the N+1-th stand _3N+1 has a flatwork roll 4a2 with a uniform roll diameter to roll the steel plate S as the rolling target material.

Further, in the cold rolling method, the cold rolling equipment, and the method for manufacturing a cold-rolled steel sheet according to the present invention, among the plurality of stands 3 ₁ to 3 ₄ , the upstream side in the conveying direction of the steel sheet S as the material to be rolled The N-th stand 3 N arranged at the N-th (N is a natural number of 2 or more) from the N-th stand 3 _N and the N + 1-th stand 3 _{N + 1 arranged at the N + 1-th downstream side of the N-th stand 3 N} are each a roll 4 aa having a uniform diameter It is assumed that there is a tapered work roll 4a1 formed with a taper 4ab at its end. Then, at the N-th stand 3 _N and the N + 1-th stand 3 _{N + 1} , with a linear load of 1.7 t / mm or more, and at each of the N-th stand 3 _N and the N + 1-th stand 3 _{N + 1.} Formed on the tapered work roll 4 a 1 The steel plate S is rolled with the taper rolling portion width WRδ, which is the length of the taper 4ab facing the steel plate S, set to between −50 mm and −5 mm.

Then, in the cold rolling method, the cold rolling equipment, and the method for manufacturing a cold-rolled steel sheet according to the present invention, among the plurality of stands 3 ₁ to 3 ₄ , the N+2th stand on the downstream side of the N+1th stand _3N+1 It is preferable that the N+2th stand _3N+2 has a flat work roll 4a2 with a uniform roll diameter to roll the steel plate S as the rolling target material.
Further, in the first and second embodiments, the magnetic steel sheet was used as the material to be rolled in the test, but the steel type of the steel sheet S is not limited to the magnetic steel sheet. Stainless steel sheets, high-carbon steel sheets, electrical steel sheets, and the like are known as steel types in which edge cracks are generally likely to occur. A remarkable effect appears by applying the manufacturing method of the steel plate.

In order to verify the effects of the present invention, cold rolling was performed using cold rolling equipment 1 under the conditions shown in Tables 5 and 6. In Tables 5 and 6, the rolling reduction is calculated based on the thickness of the material to be rolled on the entry side of the _first stand 31 and the thickness of the material on the delivery side of the _fourth stand 34 .

In Invention Examples 1 to 4, the material to be rolled is electromagnetic steel sheet A, in Invention Examples 5 to 8, the material to be rolled is electromagnetic steel sheet B, and in Invention Examples 9 to 12, the material to be rolled is electromagnetic steel sheet C. , the tapered work roll 4a1 is applied to the _second stand 32, the line load of the _second stand 32 is 1.4 t/mm or more, and the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 is was set between −50 mm and −5 mm within the range. In any of Invention Examples 1 to 12, the edge drop ratios of the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) are within the appropriate range, and Invention Examples 1 to 12 There was no edge cracking for each of the 12.

Further, in Comparative Example 1, the material to be rolled is electromagnetic steel sheet A, in Comparative Example 4, the material to be rolled is electromagnetic steel sheet B, and in Comparative Example 7, the material to be rolled is electromagnetic steel sheet C, and the tapered work roll 4a1 is the second stand 3. ₂ , the linear load of the _second stand 32 is 1.4 t / mm or more, and the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is set to -60 mm outside the range in the negative direction. Rolled. In all of Comparative Examples 1, 4, and 7, the stand (second stand 3 ₂ ) raised the edge, and edge cracks occurred in each of Comparative Examples 1, 4, and 7. .

Further, in Comparative Example 2, the material to be rolled is electromagnetic steel sheet A, in Comparative Example 5, the material to be rolled is electromagnetic steel sheet B, and in Comparative Example 8, the material to be rolled is electromagnetic steel sheet C, and the tapered work roll 4a1 is the second stand 3. ₂ , the linear load of the _second stand 32 is 1.4 t / mm or more, and the taper rolling portion width WRδ of the taper work roll 4a1 of the _second stand 32 is +5 mm outside the range in the positive direction. did In any of Comparative Example 2, Comparative Example 5, and Comparative Example 8, the stand (third stand 3 ₃ ) next to the stand (second stand 3 ₂ ) edged up, and Comparative Example 2, Comparative Example 5, and Comparative Example 8 had edge cracks.

In Comparative Example 3, the material to be rolled was electromagnetic steel sheet A, in Comparative Example 6, the material to be rolled was electromagnetic steel sheet B, and in Comparative Example ₉ , the material to be rolled was electromagnetic steel sheet C. Flat work rolls were applied at the _4th stand 34, and rolling was performed at a linear load of 1.4 t/mm or more at the _second stand 32. In any of Comparative Example 3, Comparative Example 6, and Comparative Example 9, the stand (third stand 3 ₃ ) next to the stand (second stand 3 ₂ ) having a flat work roll was edged up, and Comparative Example 3, Comparative Each of Example 6 and Comparative Example 9 had edge cracks.

In Reference Example 1, the material to be rolled is an electromagnetic steel sheet D, the tapered work roll 4a1 is applied to the _second stand 32, and the line load of the _second stand 32 is 0.75 t/mm, which is out of the range, and Rolling was performed with the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 set to -5 mm. In Reference Example 2, the material to be rolled is an electromagnetic steel sheet D, the tapered work roll 4a1 is applied to the _second stand 32, and the line load of the _second stand 32 is 0.75 t/mm, which is out of the range, and Rolling was performed with the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 set to 0 mm. In Reference Example 3, the material to be rolled is an electromagnetic steel sheet D, the tapered work roll 4a1 is applied to the _second stand 32, and the line load of the _second stand 32 is 0.75 t/mm, which is out of the range, and Rolling was performed with the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 being +60 mm. Furthermore, in Reference Example 4, the material to be rolled is the electromagnetic steel sheet D, flat work rolls are applied to all the first stands 3 ₁ to the fourth stand 3 ₄ , and the linear load of the second stand 3 ₂ is set to 0.00, which is out of range. Rolling was performed at 75 t/mm or more. In the case of Reference Example 1, by shifting the _second stand 32 in the negative direction under ultra-light pressure, the edge was raised at the _second stand 32, resulting in edge cracking. In the case of Reference Examples 2 to 4, the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 was changed to ±0 mm, +60 mm, and flat work rolls, but the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) are within the appropriate range, and there is no edge crack in each of Reference Examples 2 to 4, and the second stand 3 ₂ is replaced by the tapered work roll 4a1. There was no such effect.

Further, in Invention Examples 17 to 20, the material to be rolled is an electromagnetic steel sheet E, in Invention Examples 21 to 24, the material to be rolled is an electromagnetic steel sheet F, and in Invention Examples 25 to 28, the material to be rolled is an electromagnetic steel sheet. G, the tapered work roll 4a1 is applied to the second stand 3 ₂ , and the line load of the second stand 3 ₂ is within the range of 0.8 t / mm or more and less than 1.4 t / mm, and the second stand 3 ₂ Rolling was performed with the tapered rolling portion width WRδ of the tapered work roll 4a1 in the range of ±0 mm to +50 mm. In any of Invention Examples 17 to 25, the edge drop ratio of the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) is within the proper range, and Invention Examples 1 to 25 There was no edge cracking for each of the 12.

Further, in Comparative Example 10, the material to be rolled is the electromagnetic steel sheet E, in Comparative Example 13, the material to be rolled is the electromagnetic steel sheet F, and in Comparative Example 16, the material to be rolled is the electromagnetic steel sheet G, and the tapered work roll 4a1 is the second stand 3. ₂ , the linear load of the _second stand 32 is 0.8 t / mm or more and less than 1.4 t / mm, and the taper rolling portion width WRδ of the taper work roll 4 a1 of the _second stand 32 is set in the positive direction Rolling was performed with +60 mm outside the range. In any of Comparative Examples 10, 13, and 16, the stand (third stand 3 ₃ ) next to the stand (second stand 3 ₂ ) is edged up, and Comparative Example 12, Comparative Example 15, and Comparative Example There was edge cracking for each of the 18.

Further, in Comparative Example 11, the material to be rolled is the electromagnetic steel sheet E, in Comparative Example 14, the material to be rolled is the electromagnetic steel sheet F, and in Comparative Example 17, the material to be rolled is the electromagnetic steel sheet G, and the tapered work roll 4a1 is the second stand 3. ₂ , the line load of the _second stand 32 is 0.8 t / mm or more and less than 1.4 t / mm, and the taper rolling portion width WRδ of the taper work roll 4 a1 of the _second stand 32 is set in the negative direction Rolling was performed at −5 mm outside the range. In any of Comparative Examples 11, 14, and 17, the stand (second stand 3 ₂ ) raised the edge, and there was edge cracking in each of Comparative Examples 11, 14, and 17. .

In Comparative Example 12, the material to be rolled was electromagnetic steel sheet E, in Comparative Example ₁₅ , the material to be rolled was electromagnetic steel sheet F, and in Comparative Example 18, the material to be rolled was electromagnetic steel sheet G. Flat work rolls were applied at the _4th stand 34, and rolling was performed at a linear load of 0.8 t/mm or more and less than 1.4 t/mm at the _second stand 32. In any of Comparative Example 14, Comparative Example 17, and Comparative Example 20, the stand (third stand 3 ₃ ) next to the stand (second stand 3 ₂ ) having a flatwork roll was edged up. There were edge cracks in each of Example 15 and Comparative Example 18.

In Invention Example 13, the material to be rolled is the magnetic steel sheet A, the tapered work roll 4a1 is applied to the _second stand 32, the line load of the _second stand 32 is 1.45 t / mm, and the second stand 32 Rolling was performed with the tapered rolling portion width _WRδ of the tapered work roll 4a1 of No. 32 set to −30 mm within the range. The inclination L/H of the taper 4ab of the tapered work roll 4a1 was set to 1/400, which is within the preferred range. In Inventive Example 13, the edge drop ratios of the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) were within appropriate ranges, and there was no edge cracking.

In addition, in Invention Example 14, the material to be rolled is the magnetic steel sheet H, the tapered work roll 4a1 is applied to the second stand 3 ₂ and the third stand 3 ₃ , and the linear load is applied to the second stand 3 ₂ and the third stand 3 ₃ Rolling was performed at 1.72 t/mm and with the taper rolling portion width WRδ of the taper work rolls 4a1 of the _second stand 32 and the _third stand 33 being -30 mm within the range. In Inventive Example 14, the edge drop ratios of the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) were within appropriate ranges, and there was no edge cracking.

Further, in Invention Example 15, the material to be rolled is a stainless steel plate, and in Invention Example 16, the material to be rolled is a high-carbon steel plate, the tapered work roll 4a1 is applied to the _second stand 32, and the line load of the _second stand 32 is set to Rolling was carried out at 1.4 t/mm or more, and with the tapered rolling portion width WRδ of the tapered work roll 4a1 of the _second stand 32 set to -30 mm within the range. In both Invention Examples 15 and 16, the edge drop ratios of the stand (second stand 3 ₂ ) and the next stand (third stand 3 ₃ ) are within the appropriate range, indicating Invention Examples 15 and 16. There was no edge cracking for each of the 16.

1 cold rolling equipment 2 rolling mill 3 _1st stand 3 _2nd stand 3 _3rd stand 3 _4th stand 3 _Nth stand 3 _N+ 1th N+1 stand 3 _N+ 2th N+2 stand 4a Work rolls 4a1 taper work roll 4a2 flat work roll 4aa roll 4ab taper 4ac taper start end 4b backup roll 4c intermediate roll S steel plate (rolling target material)

Claims (13)

A cold rolling method for cold rolling a material to be rolled by a rolling mill equipped with a plurality of stands,
Among the plurality of stands, the N-th stand (N is a natural number of 2 or more) arranged from the upstream side in the conveying direction of the material to be rolled has a tapered end portion of a roll having a uniform diameter. It has tapered work rolls,
The Nth stand rolls the rolling target material with a linear load of 0.8 t / mm or more ,
When the N-th stand rolls the material to be rolled with a linear load of less than 1.4 t / mm, the taper formed on the tapered work roll of the N-th stand has a length facing the material to be rolled A cold rolling method characterized by rolling the material to be rolled with a taper rolling portion width WRδ of between ±0 mm and +50 mm . When the N-th stand rolls the material to be rolled with a linear load of 1.4 t / mm or more, the length of the taper formed on the tapered work roll of the N-th stand facing the material to be rolled 2. The cold rolling method according to claim 1 , wherein the tapered rolling portion width WRδ is between −50 mm and −5 mm. Among the plurality of stands, the N+1th stand arranged at the N+1th downstream side of the Nth stand has a flat work roll with a uniform roll diameter and rolls the material to be rolled. The cold rolling method according to claim 1 or 2 . A cold rolling method for cold rolling a material to be rolled by a rolling mill equipped with a plurality of stands,
Among the plurality of stands, the N-th stand (N is a natural number of 2 or more) from the upstream side in the conveying direction of the material to be rolled and the N+1-th downstream side of the N-th stand The N+1 stand has tapered work rolls with tapered ends of rolls of uniform diameter,
The N-th stand and the N+1-th stand each have a linear load of 1.7 t / mm or more, and the tapers formed on the tapered work rolls of the N-th stand and the N+1-th stand are the rolling objects A cold rolling method, wherein the material to be rolled is rolled with a taper rolling portion width WRδ, which is a length facing the material, between -50 mm and -5 mm. Among the plurality of stands, the N+2th stand arranged at the N+2th downstream side of the N+1st stand has a flat work roll with a uniform roll diameter and rolls the material to be rolled. The cold rolling method according to claim 4 . 3. The stand arranged most upstream in the conveying direction of the material to be rolled among the plurality of stands has flat work rolls having a uniform roll diameter to roll the material to be rolled. 6. The cold rolling method according to any one of 1 to 5 . A cold rolling facility equipped with a rolling mill having a plurality of stands for cold rolling a material to be rolled,
Among the plurality of stands, the N-th stand (N is a natural number of 2 or more) arranged from the upstream side in the conveying direction of the material to be rolled has a tapered end portion of a roll having a uniform diameter. It has tapered work rolls,
The line load of the Nth stand is set to 0.8 t/mm or more ,
When the line load of the Nth stand is set to less than 1.4 t / mm, the taper formed on the tapered work roll of the Nth stand has a length that faces the material to be rolled. Cold rolling equipment characterized in that the part width WRδ is between ±0 mm and +50 mm . When the line load of the N-th stand is set to 1.4 t / mm or more, the taper rolling, which is the length of the taper formed on the tapered work roll of the N-th stand that faces the material to be rolled Cold rolling equipment according to claim 7 , characterized in that the part width WRδ is between -50 mm and -5 mm. 9. The N+1-th stand arranged at the N+1-th downstream side of the N-th stand among the plurality of stands has a flatwork roll with a uniform roll diameter. Cold rolling equipment. A cold rolling facility equipped with a rolling mill having a plurality of stands for rolling a material to be rolled,
Among the plurality of stands, the N-th stand (N is a natural number of 2 or more) from the upstream side in the conveying direction of the material to be rolled and the N+1-th downstream side of the N-th stand The N+1 stand has tapered work rolls each having a uniform diameter and tapered at the ends of the rolls,
The line loads of the Nth stand and the N+1 stand are each set to 1.7 t / mm or more, and the tapers formed on the tapered work rolls of the Nth stand and the N+1 stand are the rolling A cold rolling facility characterized in that a tapered rolling portion width WRδ, which is a length facing a target material, is between -50 mm and -5 mm. 11. The cold mill according to claim 10 , wherein, of the plurality of stands, the N+2-th stand located downstream of the N+1-th stand has a flatwork roll with a uniform roll diameter. rolling equipment. 12. Any one of claims 7 to 11 , wherein, of the plurality of stands, the stand arranged most upstream in the conveying direction of the material to be rolled has a flatwork roll with a uniform roll diameter. The cold rolling equipment described in . A method for manufacturing a cold-rolled steel sheet, comprising cold-rolling a steel sheet by the cold-rolling method according to any one of claims 1 to 6 to manufacture a cold-rolled steel sheet.

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