JPH06190415A - Cold tandem rolling method for metallic strip - Google Patents

Abstract

PURPOSE:To obtain, through a cold tandem continuous mill, a steel strip and other metallic strips requiring high luster in stainless steel, JIS-SC, JIS-SK, etc., excellent in surface properties, plate crown or shape or having high defor mation resistance, high luster or smoothness by containing high Ni. CONSTITUTION:In a metal rolled, by the cold tandem mill, the diameters of work rolls at the final stand and at the stand directly before it are given by 250-100mm, the draft at the final stand is given by 2-15% and the accumulative draft in the two stands is given by 20-40%. A material to be rolled is rolled by a pair of work rolls arranged so that a tapered part which is taper-ground at least to a one-sided edge part at preceeding stands other than two stands in the mill is positioned at edge parts on both sides of the material to be rolled, or, at a stand position where a pair of upper and lower work rolls which can be intersected at the horizontal position are combined as they are paired with backup rolls.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold tandem rolling method for metal strips, which has a surface characteristic by a cold tandem continuous rolling mill,
To obtain steel strips and other metal strips that are required to have high gloss such as stainless steel and JIS standards SC and SK with excellent plate crown or shape, or high deformation resistance such as high Ni content and high gloss or smoothness. It is intended to provide a possible method.

[0002]

2. Description of the Related Art For cold rolling of stainless steel and others, rolling has been conventionally performed by using a small-diameter work roll typified by a Zenzimer mill and a rolling oil mainly containing neat oil. It is becoming mainstream to use a cold tandem rolling mill with a large roll diameter instead of rolling with a small diameter mill such as a Zenzimer.

However, such rolling with a large-diameter roll is still a rough rolling position for high-quality materials,
The main reason for this is that rolling with a large-diameter mill results in a large amount of rolling oil being drawn into the roll bite, which inevitably results in the formation of large oil pits, leading to a decrease in surface gloss and an increase in roughness. . For this reason, it has been proposed to use a work roll of medium diameter in the latter stage of the cold tandem mill as described above. JP-A-59-38334 and 59-107030
150 mm or more, and in JP-A-63-119908, 40 mm or more.
It has been proposed to employ ones of 0 mm or less.

Regarding rolling in a small-diameter mill such as a Zenzimer mill, the surface characteristics of a stainless original plate material are high gloss and low roughness, which means that if the original plate is good, the number of rolling passes in a small-diameter mill such as a Zenzimer mill will decrease. This is because the steel strip having an excellent surface shape is manufactured because the production efficiency is improved. In addition to this, there is a low plate crown as a requirement for rolling material for small diameter mills. This is because if the edge drop of the original material is large, the work end cannot be sufficiently pressed down by the small diameter work roll, and the material is on the end side. Compared with the above, rolling progresses in the central part side and tensile stress is generated at the end of the material, and at the end of the plate, the effect of equalizing the rolling pressure distribution in the plate width direction due to the tension feedback is weakened and the end breaks. Is likely to occur. Therefore, conventionally, hot rolling-
This problem has been dealt with by performing trimming after pickling or after cold rolling. As a method for avoiding the trouble at the time of trimming, Japanese Patent Application Laid-Open No. 61-95702 discloses grinding with a rotary grindstone. .

[0005]

Even when a work roll of a medium diameter level is applied to the latter stage of the cold tandem rolling mill described above, there is a large difference from the work roll diameter of 500 to 600 mmφ in the preceding stage, If the material edge drop on the entry side of the latter-stage medium-diameter work roll is large, rupture occurs, and it is inevitable that a significant shape defect will occur in the medium-diameter mill.

This is due to the occurrence of tensile stress at the above-mentioned plate edge and the difference in the ratio of the large-diameter mill exit-side crown and the medium-diameter mill exit-side crown that is assumed from the plate crown estimation formula shown in the following Equation 1. Therefore, the term of roll flatness is neglected in the formula I, and the difference in roll flatness between large diameter and medium diameter also causes the problem.

[0007]

[Equation 1]

Particularly in a continuous cold tandem rolling mill for changing the running plate thickness, in order to keep the plate crown on the entrance side of a medium diameter mill with a large edge drop and the crown ratio at the exit side substantially constant, It must be said that it is extremely difficult, including the roll deflection control preset of.

Even if trimming of the original plate material by the above-mentioned rotary grindstone is carried out to avoid breakage in a small-diameter mill such as a Zenzimer, it is natural that the number of man-hours is increased and the yield is reduced. It is not a fundamental solution for eliminating, improving productivity, and improving.

[0010]

Means for Solving the Problems In the present invention, repeated studies have been made to solve the problems in the prior art as described above, and plate crown control by a front stand is carried out so that a medium-roll-entrance plate crown in the same mill is installed. By improving it, the contact arc length in the roll bite due to becoming a medium diameter roll becomes shorter than that of a large diameter roll, including the effect of reducing the deterioration of edge drop that occurs as a result, the plate crown and shape on the exit side of the final stand The present invention succeeds in improving the surface characteristics and is as follows.

In the cold tandem rolling mill, the work roll diameter is set to 2 at the last and the last two stands immediately before it.
50 to 100 mm, and the final stand rolling reduction is 2 to
The metal was rolled to 15% and the cumulative rolling reduction in the final two stands was set to 20 to 40%, and at least one side end was tapered and ground in a front stand other than the final two stands in the rolling mill. A pair of work rolls, which is composed of an array in which the tapered portions are located at both end portions of the rolled material,
Alternatively, a cold tandem rolling method for a metal strip, which comprises rolling with a stand arrangement in which a pair of upper and lower work rolls that can be paired with a backup roll and cross each other in a horizontal plane are assembled.

[0012]

In the cold tandem rolling mill, the work roll diameter in the last and the last two stands immediately before is 250.
The surface property of the metal strip can be improved by setting the thickness to 100 mm, but in this case, the final stand rolling reduction is 2 to
The glossiness and other surface properties are effectively improved by rolling the metal strip with a cumulative rolling reduction of 20% to 40% in the last two stands while adjusting to 15%.

In the former stand excluding the above-mentioned final stand and the last two stands immediately before it in the rolling mill, at least one side end is tapered and ground and tapered parts are positioned at both side ends of the material to be rolled. A pair of work rolls, or a pair of backup rolls, are rolled by a stand arrangement in which a pair of upper and lower work rolls that can cross in a horizontal plane are assembled to prevent breakage of the metal strip in the rolling method as described above, and it is good. A metal plate having a flat plate crown is obtained.

[0014]

EXAMPLES To explain the details of the present invention as described above, the present inventors first examined various changes in the combination relationship between the large diameter roll and the medium diameter roll. That is, regarding a combination of a large diameter roll having a diameter of 450 to 600 mm and a medium diameter roll having a diameter of 100 to 250 mm, as shown in Table 1 below regarding the first to fifth stands, only the first stand is a large diameter roll and the second is a second diameter roll. From the case where the fifth stand is a medium diameter roll, the first to fifth stands are all large diameter rolls in various combinations, and for the plate crown control, the taper portion is used in all of the large diameter roll stands. Table 1 shows the results of a study conducted by rolling by using rolls positioned at both end portions of the rolled material so as to be shifted in the width direction of the metal strip. Figure 1 summarizes the above.

[0015]

[Table 1]

That is, in case A, only the first stand is 600
With a large diameter roll of mm, each of the second to fifth stands is 200
In the case of adopting a medium diameter roll of mm, the first stand was subjected to reduction by the large diameter roll, and then the second stand was tried to be reduced by the medium diameter roll. Due to the influence of the entrance side plate crown (large edge drop), the obtained reduction rate is largely restricted,
Both the final glossiness and the edge drop were insufficient. In case B, the first and second stands are large-diameter rolls, and the third stand is
~ 5 The case where the stand is a medium diameter roll, but similar to case A, it is slightly affected by the bite restriction and the plate crown,
The reduction rate obtained is reduced and the final glossiness is insufficient.

On the other hand, in case C, the first to third stands are large-diameter rolls, and the fourth and fifth stands are medium-diameter rolls, and a large reduction ratio is ensured even in a large diameter, which is caused by shifting. By improving the plate crown (0.2% edge drop), there is almost no restriction on the reduction due to the middle diameter of the 4th and 5th stands, large reduction can be taken, and the final glossiness is also the best.
The edge drop was also good.

Further, in case D, the first to fourth stands are large-diameter rolls, and only the fifth stand is a medium-diameter roll, and the reduction rate obtained by the medium-diameter roll is also limited by the final stand tension balance. Low. Although the final edge drop is smaller than that for controlling the crown up to the fourth stand, the gloss is insufficient, which is not preferable. Further, in case E, all the stands are made of large-diameter rolls, which is considerably insufficient in terms of gloss.

Next, the present inventors examined whether the gloss of stainless steel strip or the like could be improved by adopting only the final stand of the case D as a medium diameter roll and changing the diameter to adopt a medium or small diameter roll. The results are shown in Table 2 below, and it was known that the desired glossiness could not be achieved even when a medium-diameter roll was used only for the final stand and a small-diameter roll of 100 mm was adopted.

[0020]

[Table 2]

That is, in case 1 in Table 2, when all the stands are made by rolling stainless steel material with a large-diameter roll of 600 mm, the material is work-hardened as the stand becomes the latter stage, and the roll flatness due to high load is also large. It became 10% at the final stand due to load and shape restrictions.
You can only get a certain reduction rate. In Case 2, the final stand had a roll diameter of 400 mm, which is a semi-large diameter state, but again, due to load and shape restrictions, only 13% reduction in the final stand was obtained, and the gloss was also very wide. No significant improvement was recognized.

On the other hand, in case 3, the final stand had a roll diameter of 250 mm, and although there was a restriction due to the shape, a reduction ratio of 16% was obtained under a low load and the gloss was improved to some extent. Was confirmed, and the significance of using a medium-diameter roll for the final stand could be recognized, but this alone was not sufficient. In case 4, the final stand has a roll diameter of 200 mm and the stainless steel material is rolled. In this case, the final stand has an unbalanced tension, and the final stand has a reduction ratio of more than 15%. Then slip occurred. In order to reduce the difference between the take-up tension on the exit side of the final stand and the tension on the entrance side of the final stand, it is necessary to lower the tension on the entrance side of the final stand, and the reduction rate of the 4th stand also decreases and the glossiness is the same as in Case 4. It was a level.

Further, in case 5, the final stand has a roll diameter of 100 mm, which is smaller than that of the above-mentioned table 1 having a diameter of 200 mm, but is subject to the same restrictions as case 4, and further 100 mm. We also examined the case where the roll diameter is less than the above, but in such a case, a new speed constraint is required in consideration of accident resistance, etc., and the effect of utilizing a cold tandem rolling mill for stainless rolling (production capacity It is clear that the improvement) will fade.

From these results, the roll diameter range is 100 to 250 mm, but even if such a medium diameter roll is incorporated only in the final stand and rolling is performed, due to the above-mentioned restriction, the obtained reduction ratio is reduced. Has a limit, and the glossiness is 320 at the maximum, and it is clear that a large improvement effect cannot be obtained.

Further, by rolling Cases 1 to 5, the glossiness after rolling of the stainless steel material is greatly influenced not only by the total reduction ratio but also by the reduction ratio obtained by the roll stand having a smaller diameter than that of the preceding stand. Was known to receive.

Further, as described above, the preferable result cannot be obtained by adopting the medium and small diameter rolls only in the final stand. Therefore, the medium diameter roll is also used in the stand just before the last of the case C in which the preferable result is obtained in Table 1 above. Table 3 below shows the results of the study on obtaining the high pressure reduction rate between the last stand (4th stand) and the last stand (5th stand).

[0027]

[Table 3]

That is, in case 6, rolling was carried out with the rolling reduction of the immediately preceding final stand set to 10%, but the final stand was restricted by the slip and only a rolling reduction of 15% was obtained. Further, in Cases 7 and 8, the rolling reduction rate at the last stand immediately before the end was raised to 15% and 20%, and the final stand was subjected to the rolling reduction constraint due to slip as in the above.
Further, in case 9, since the edge drop of the material immediately before the final stand was large, the plate edge overtension was generated for the above reason, and a significant shape defect or breakage occurred at a rolling reduction of more than 25%.

On the other hand, in case 10, the last two stands have a roll diameter of 200 mm, and the plate crown control is performed in the other stands to reduce the edge drop of the material entering the stand immediately before the last stand. In, you can get a large reduction of 35%,
As a result, the glossiness was greatly improved.

In case 10, however, the final stand entry side (rear) tension needs to be higher than the take-up tension as the obtained reduction ratio up to the final stand entry side increases. When the rolling reduction ratio of more than 35% is taken at the last stand (4th stand) due to the imbalance of No. 3, slip still occurs as shown in FIG. If the winding tension is increased against such a slip, the difference with the tension on the inlet side of the final stand becomes smaller,
Although the restriction of the obtained rolling reduction ratio due to slip is relaxed, if the winding tension is made too high, a kink (winding tightness) of the winding coil inner diameter occurs, resulting in a large production yield loss. Therefore, it is preferable to keep the winding tension constant, for example, 5.5 kg / mm ² .

As for the case 10 in Table 3 above, the plate crown control in the front stage stand excluding the last and immediately before the last stand (two stands immediately before the last) is shown in FIG.
As shown in Fig. 1, at least one side end of the rolling roll is formed with a tapered tapered portion, and is rolled by being positioned at both side ends of the material to be rolled, and θ ₁ is a large taper angle of the tip, θ ₂ is the small taper angle formed adjacent to it, L ₁ is the taper length in the taper angle θ ₁ region, L ₂ is the taper length in the taper angle θ ₂ region, and WRδ is the material to be rolled. And the taper θ ₁ and θ ₂ overlap.

An example of the numerical values relating to θ ₁ and θ ₂ , L ₁ and L ₂ specifically adopted is as follows. WRδ is 90 for the first stand, 80 for the second stand and 75 for the third stand. The initial setting was used. tan θ ₁ = 0.005 L ₁ = 380 tan θ ₂ = 0.001 L ₂ = 70 However, these values should be appropriately selected in combination with WRδ for each deformation resistance of the material within the following range. it can. tan θ ₂ range: 5 × 10 ^-4 ≦ tan θ ₂ ≦ 5 × 10 ^-3 L ₂ range: 20 ≦ L ₂ ≦ 200 mm tan θ ₁ range: 1 × 10 ^-3 ≦ tan θ ₁ ≦ 1 × Range of 10 ^-2 L ₁ : Allowed if L ₁ ≥ 0 However, as an absolute condition θ ₁ > θ ₂

In the case of a pair cross device with a backup roll, a flat roll is used as the work roll, and the cross angle is 0.8 ° for the first stand and 0.6 for the second stand.
°, adopt the default setting such as 0.3 for the 3rd stand.

The cold tandem rolling carried out by the inventors of the present invention will be concretely explained based on the above-mentioned examination results. As a cold rolling equipment such as a stainless steel strip, as shown in FIG. Roll 9 and 100-
The first to fifth stands 3 to 7 using a 250 mm medium diameter work roll 10 are provided, and stainless steel and other steel strips 8 are fed into these stands and rolled to form the third stand 5
The profile meter 1 for measuring the plate crown on the medium diameter mill entrance side is provided between the fourth stand 6 and the fourth stand 6, and another profile meter 2 for measuring the plate crown of the final product is provided on the exit side of the final stand. The steel strip 8 made of stainless steel is rolled while being provided with these profile meters 1 and 2, and the roll diameter of each stand, the change of the plate crown ratio due to the distribution of the reduction ratio, and the obtained reduction ratio limit at the final stand are set. The operating conditions of the present invention and the comparative example are shown in Table 4 below.

[0035]

[Table 4]

That is, each stand is a case 11 using only large-diameter rolls and a case 1 using plate crown control.
In case of 1 ', even if the edge drop (or crown) is changed, the lack of gloss after rolling cannot be improved, and in cases 12 to 19' in which the medium diameter roll is adopted after the fourth stand, The gloss reduction can be improved, and the marginal reduction rate and cumulative reduction rate in the 4th and 5th stands in that case are as shown in Table 4. If it is within such a limit, a preferable product can be obtained. It was confirmed.

That is, the case 12 to 13 'is the first
~ The case where the reduction rate of the third stand is constant and the cumulative reduction rate obtained in the fourth stand and the fifth stand is constant, and the reduction rate up to the third stand is the same in cases 14 to 19 '. And the fourth and fifth
When the rolling reduction rate at the stand is gradually increased,
Cases 12 to 13 'have a certain glossiness, whereas cases 14 and below have fourth and fifth stands,
In particular, it was confirmed that the glossiness after rolling can be effectively increased by increasing the rolling reduction of the fourth stand.

In each of Tables 1 to 4, a roll having a large diameter of 600 mm was used as a reference, but the practical upper limit in this case is about 600 mm,
If the diameter is made larger than this, the load for obtaining the desired rolling reduction increases, the rolling torque also increases, and the roll cylinder length is generally set to a maximum of 6 width mill in this kind of cold rolling mill. Therefore, the bending effect of the work roll is reduced and the shape control ability is also reduced, so it was adopted as the limit standard roll diameter.

Further, as the latter-stage medium diameter roll, typically 200
mm is adopted in the medium diameter roll range of the present invention 100 to 250
This is because the roll diameter is in the middle of mm, and it is presumed to be preferable for understanding the technical relationship of the latter-stage intermediate-diameter roll in the present invention substantially appropriately.

The above-mentioned cases 12, 12 ', 14, 1
From the results of 4 ', 15, and 15', the relationship between the final stand rolling reduction rate and the ease of slippage is summarized and shown in FIG. That is, the larger the tension drop between the inlet side and the outlet side of the final stand, the greater the restriction on the final stand reduction due to slippage, and in case 15, there is a very large restriction.

Further, in the case of this embodiment, the plate crown control is as shown in FIGS. 8 and 9 respectively, and in FIG. 8, the strip 11 passes through each of the stands 3 to 7 as described above. It is well known that the roll taper of each of the rolling stands 3, 4 and 5 of the strip 11 and the overlapping amount WRδ of the material are set in advance in the computer with respect to such equipment. At the same time, the target plate crowns on the exit sides of the stands 3, 5, and 7 are also set in the form of formulas.

However, first, in the rolling stand 3, the strip crown of the strip 11 on the stand exit side is measured by the profilometer 13, and the deviation from the target strip crown is changed to the stand WRδ as shown in FIG. To fix. As a matter of course, the WRδ that can be operated under a certain roll taper size is limited, and a computer is preliminarily calculated so that a defective shape (middle stand middle elongation tendency) and plate breakage due to the plate edge slit do not occur. The upper limit value A point of WRδ which is WRδA is also set inside, and as a result of performing the above plate crown control in the rolling stand 3,
If the target plate crown is reached, the rolling is continued as it is. If not, WRδ is held as WRδA.

Further, in the rolling stands 4 and 5, the strip crown of the strip 11 on the exit side of the rolling stand 5 is measured by the profilometer 14, and the deviation from the target strip crown is distributed with a certain distribution to the second and third rolling stands. By changing 4, 5 WRδ, for example, it is corrected in proportion to the contact arc length or the average deformation resistance during rolling of the roll and the material. Further, similarly to the control in the rolling stand 3, the upper limit value A point of WRδ is set in the calculator in the rolling stands 4 and 5 in advance.

As a result of performing the plate crown control in the rolling stands 4 and 5, if the target plate crown is reached, the rolling is continued as it is. If not, WRδ is held as WRδA as shown in FIG. When the strip crown of the strip 11 on the exit side of the rolling stand 5 does not become the target strip crown, and the WRδ of the rolling stands 4 and 5 is already WRδ.
In A, when WRδ of the rolling stand 3 has not reached point A, the target plate crown on the exit side of the rolling stand 3 is changed to cope with the situation. WRδ of rolling stands 3, 4, and 5 are all W
If the rolling is performed at RδA and the delivery side plate crown of the rolling stand 5 does not reach the target plate crown, it is necessary to change the roll taper.

The exit side of the rolling stand 7, that is, the final strip crown is measured by the profile meter 15 as shown in FIG. 8, and when the target strip crown is not obtained, and the strip crown on the exit side of the rolling stand 3 becomes the stand WRδA. When the target plate crown is obtained with WRδ that does not reach, the target plate crown of the rolling stand 3 is changed. Similarly, when the final plate crown does not become the target plate crown, and when the plate crown on the exit side of the rolling stand 5 is the target plate crown within the range where WRδ of the rolling stands 4 and 5 does not reach WRδA, The target plate crown on the delivery side of the rolling stand 5 is changed, and the plate crown control flow is as shown in FIG.

FIGS. 7 and 9 show another example of the plate crown control flow and profile meter arrangement for plate crown control according to the present invention. That is, each of the first to third stands 3, 4, and 5 performs profile closed-loop control in each of the stands, and the fifth side of the stand 7 outputs the measured profile to determine the targets of the first to third stands 3, 4, and 5. Change the profile to get the target plate crown.

FIG. 7 shows the control flow in this case, but by doing so, the desired plate crown can be appropriately obtained. The present invention is not limited to the one shown in FIGS. 6 to 9 as described above, but the target profile (plate crown) of the first to third stands 3, 4 and 5 is determined by the output measurement profile of the fifth stand 7, for example. ) May be changed at the same time with a certain distribution relationship (coefficient). As the distribution, there is a method proportional to the contact arc length of the first to third stands in the rolled state, a method proportional to the average deformation resistance, or the like.

Further, in the rolling as described above, the inventors of the present invention have shown that the change of the edge drop of each stand by applying the work roll shift of the first stage is as shown in FIG. 5, and the medium diameter roll is used in the latter stage. In rolling, the deformation resistance of the material is large and the contact arc length is also short, so the deterioration of the edge drop has hardly progressed. Therefore, in this case, it is possible to determine whether or not a good final exit side crown and shape can be obtained using the plate crown on the exit side of the third stand as a key.

Further, from the above-mentioned FIG. 2, under the above-mentioned rolling conditions in which the former-stage large-diameter and latter-stage medium-diameter roll stands are combined in the same mill, the plate crown on the medium-diameter mill entrance side is shown in FIG. It has been confirmed that by providing the meter 1 and measuring and controlling it, it is possible to appropriately prevent breakage in the latter stand and appropriately obtain a stainless steel plate having a good plate crown.

The plate crown required on the exit side of the final stand 7 varies depending on the required accuracy in the longitudinal direction and the width direction of the product steel strip. For example, when rolling is performed by a cold tandem rolling mill and then rolling is performed by a small-diameter mill, and the required crown accuracy of the product is not so severe, the shape of the medium-sized roll stand shown in FIG. The output side required crown of the final stand 7 may be set in the area of the plate crown that does not cause plate breakage.

That is, according to the present invention, the shift amounts of the first to third front stands 3, 4, and 5 are controlled based on the plate crown amount on the entrance side of the fourth stand 6 which is the medium diameter mill in FIG. By doing so, it is possible to obtain a stainless steel strip having a low crown and a good shape without breaking.

Based on the examination results shown in Tables 1 to 4, the standard first to third stands are set to 600 mm,
Since the conditions for carrying out the method of the invention when the last two stands (fourth and fifth stands) are set to 200 mm have been clarified,
The present inventor conducted further studies, and the following Tables 5 and 6 summarize the results of pursuing the implementation conditions when the roll diameters in these front and rear stands (final two stands) were changed. is there.

[0053]

[Table 5]

[0054]

[Table 6]

That is, in these Tables 5 and 6, the case numbers with a dash indicate that there is crown control in the front stand, which is not particularly shown in each table, but in the case of these crown controls, The plate shape is good. However, Cases 20 and 20 'are the case where all stands are large-diameter rolls of 550 mm, and are rolled in the same manner as Cases 11 and 11' in Table 4 described above.
Even if the gloss is increased by the amount smaller than those of Nos. 1 and 11 ', none of them is preferable because of insufficient gloss.

Cases 21 and 21 'are front stand 550.
mm, the fourth and fifth stand 200 mm roll diameters were rolled. The increase in the rolling reduction obtained by the front stand was slightly increased (compared with the cases 12 and 12 '), but the load constraint due to the work roll being reduced in diameter by 50 mm was eased. The reduction rate of the first stand has not changed in consideration of the easiness of meandering when the first stand is used too much reduction, and the occurrence of a defective shape due to the stand whose profile with the hot-rolled sheet largely changes. This is because a large reduction is not usually taken.

Case 22 shows the result of rolling by a large-diameter roll whose all stands are 500 mm, like Case 20, and all stands are 500 mm from Cases 11, 20, and 22.
When stainless steel or the like was rolled with the above-mentioned large diameter rolls, the glossiness obtained was at a low level without depending on the roll diameter. On the other hand, in case 23, the last two stands are 200
In the case of a medium-diameter roll of mm, the glossiness after rolling is significantly improved by doing so.

In case 24, as a comparison with case 21, the fourth and fifth stands in the latter stage have a roll diameter of 250 mm. Although the roll diameter of the last stand is higher than that in case 21, the final stand reduction ratio is increased. The amount of oil introduced into the roll bite increases, and the surface gloss is insufficient.

Similarly, in case 25, the roll diameter of the final stand is set to 150 mm. The final stand has slippage due to the reduction of the roll diameter, which increases the constraint on the pressure ratio, which is offset by the surface improvement effect of the reduction in diameter. It did not lead to a significant improvement in gloss.

The case 26 is 100 mm further from the final stand.
The diameter has been reduced to the same level as the case 25,
No significant improvement effect on glossiness was obtained. Cases 27 to 29 are similar to cases 24 to 26 in that the roll diameters of the fourth and fifth stands are changed.
This is a case where the first to third stands have a roll diameter of 500 mmφ.

In the cases 23 to 29 described above, the rolling reduction of the fourth stand is fixed at 10%. In contrast to such cases 23 to 29, the cases 30 to 32 'in Table 6 are the first to the first cases. 3 stand 550mm diameter, 4th and 5th stand 2
With a diameter of 00 mm, the rolling reduction of the fourth stand is increased. That is, in the case 30, the plate crown (particularly the edge drop) on the delivery side of the third stand is large and the fourth stand 23%.
Breakage occurred in the super.

In the case 30 ', the plate crown control was carried out by the first to third stands in the former stage, and the fourth and fifth stands had no restriction even if the rolling reduction was 25%. Furthermore, while performing the front stage crown control,
Although the rolling reduction rate was increased to%, the rolling reduction was limited only by the slippage of the fifth stand.

Cases 31 'and 32' carry out crown control, and the front stand and its rolling condition are case 30 and
Same as 30 ', the reduction ratio for the latter stand is changed, but the glossiness can be increased to 430 to 490 by increasing the reduction ratio of the fourth stand, and the constraint condition in the final stand It was confirmed that the preferable rolling can be performed.

Cases 33, 33 ', 34, 34' are front stands (first to third stands) and are case 30 described above.
~ 32 ', but when the work roll diameters in the fourth and fifth stands are 150 mm and 100 mm, the glossiness is 350 to 390, and the final 2
Appropriate rolling can be performed under the constraint condition of the obtained reduction ratio in the stand, and the plate shape is good in the cases 33 'and 34', but the reduction due to the plate crown and slip is accompanied by the reduction in the diameter of the subsequent rolls. The rate constraint is expanded more than in cases 30 to 32 '.

In the cases 35, 35 ', 36, 36' and 37, 37 ', the roll diameter of the first and second stands is 500 mm, and the roll diameter of the fourth and fifth stands is 100 to 200 mm. In these cases, it was confirmed that even in these cases, favorable results with glossiness of 340 to 500 can be effectively obtained under the constraint condition of final stand acquisition pressure ratio, and the same tendency as in the case of 550 mm and 600 mm in the previous stage. Was recognized.

From the above results, in any case, the work roll diameter in the final and last final two stands is 250 to 100 mm, and the final stand reduction is 2 to 15%, and the final two stands. In the rolling mill, at least one side end is tapered and at least one side is tapered so that both sides of the material to be rolled are rolled. With the arrangement of the stands composed of a pair of work rolls which are arranged in a horizontal position or a pair of upper and lower work rolls which can be paired with a backup roll and intersect each other in the horizontal plane, the final stand acquisition pressure as shown in Tables 2 to 6 can be obtained. By rolling according to the rate constraint condition, a steel strip having a gloss of at least 300 and a good plate shape can be obtained.

That is, the following Table 7 shows some of the cases other than the conditions shown in the above Tables 2 to 6 in which the plate crown control is adopted as specific examples of the present invention. As shown, all products were high in gloss and were able to appropriately obtain stable plate-shaped products.

[0068]

[Table 7]

[0069]

[Table 8]

According to the results of Tables 7 and 8 of the present invention, even if the roll diameters of the 4th and 5th stands are 100 to 250 mm, the medium diameter of the 4th stand is the same. It can be said that a relatively small diameter in the roll and a relatively large diameter in the fifth stand in the medium diameter roll are efficient in obtaining a product with high gloss.

In the cases of Tables 2 to 6, when the final stand reduction ratio is within the constraints shown in each case, it is natural that any of them can obtain a preferable product.

[0072]

As described above, according to the present invention, the cold tandem rolling mill employs a medium diameter mill in the subsequent stage, and by controlling the plate crown on the entry side of the medium diameter mill, the surface characteristics are improved. A steel strip excellent in shape and plate crown can be appropriately obtained, and the invention is industrially effective.

[Brief description of drawings]

FIG. 1 is a chart showing changes in glossiness obtained when a combination of a large-diameter roll and a medium-diameter roll is changed in a mill configuration including first to fifth stands.

FIG. 2 is a table showing the relationship between the reduction rate obtained in the last stand just before the last and the edge drop, shape defect, breakage occurrence and slip occurrence region of the material on the stand entrance side in the mill configuration including the first to fifth stands.

FIG. 3 is an explanatory diagram of a grinding taper at a roll end portion for plate crown control in the present invention.

FIG. 4 is an explanatory view schematically showing the structure of a rolling facility including five stands adopted by the present inventors.

5 is a chart summarizing the relationship between the roll diameter of each stand and the edge drop in the equipment shown in FIG.

FIG. 6 is an explanatory diagram showing an example of a plate crown control flow in the present invention.

FIG. 7 is an explanatory diagram showing another example of the plate crown control flow.

FIG. 8 is a schematic diagram showing an example of disposing a profile meter for crown control in the present invention.

FIG. 9 is a schematic view showing another example of disposition of a profile meter for plate crown control according to the present invention.

FIG. 10 is a chart showing the relationship between the final stand reduction rate and the slipperiness with respect to the final stand reduction rates of 10%, 20%, and 25%, respectively.

[Explanation of symbols]

 3 1st stand 4 2nd stand 5 3rd stand 6 4th stand 7 5th stand 8 Steel strip 9 Large diameter work roll 10 Medium diameter work roll 12 Winder 13 Profil meter 14 Profil meter 15 Profil meter

Front Page Continuation (72) Inventor Junji Koshiro 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Shigeyuki Ohno 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. In a cold tandem rolling mill, the work roll diameters in the last and the last two stands immediately before that are set to 250 to 100 mm, and the final stand reduction ratio is 2.
-15% and a rolling reduction of 20 to 40% in the final two stands is performed, and at least one side end is tapered and ground in a front stand in the rolling mill excluding the last two stands. Characterized by rolling with a stand arrangement in which a pair of work rolls consisting of an array in which the tapered portions are positioned at both end portions of the material to be rolled or a pair of upper and lower work rolls which can be paired with a backup roll and intersect in a horizontal plane are assembled. Method for cold tandem rolling of metal strip.