JP3564874B2 - Cold rolling method for sheet material with work roll shift during rolling - Google Patents

Description

【００４３】
表１から明らかなように、同一圧延条件においては、ワ−クロ−ルシフト中に、圧延油の濃度、供給量およびエマルション粒径のうちの少なくとも一つを高めて圧延したほうが、板厚の変動量は小さくなることが分かる。
【００４４】
【発明の効果】
圧延中にワ−クロ−ルシフトを行うに際して、潤滑条件の悪くなるシフトスタンドにおける潤滑状態を、シフト位置を変更する間のみ高めるようにしたので、仕上板厚の変動が防止でき、安定して冷間タンデム圧延ができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態の圧延中にワークロールシフトを行う板材の冷間圧延方法を説明するための配管系統図である。
【図２】本発明の第２の実施形態の圧延中にワークロールシフトを行う板材の冷間圧延方法を説明するための配管系統図である。
【図３】本発明を実施したときの、板厚や先進率の変化等の経時的な変化示すグラフであり、（ａ）はワ−クロ−ルシフトを行う上下ワ−クロ−ルの胴部中心とパスライン中心間の距離の変化を、（ｂ）は第１スタンド出側における板厚の変化を、（ｃ）は第２スタンド出側における板厚の変化を、（ｄ）は最終スタンドである第５スタンド出側における板厚の変化を、（ｅ）は第１スタンドにおける先進率の変化をそれぞれ示すグラフである。
【図４】本発明の第３の実施形態の圧延中にワークロールシフトを行う板材の冷間圧延方法を説明するための配管系統図である。
【図５】従来の圧延中にワークロールシフトを行う板材の冷間圧延方法を実施したときの板厚等の経時変化を示すグラフであり、（ａ）はワ−クロ−ルシフト位置の変化を、（ｂ）は第１スタンドにおける圧延荷重の変動を、（ｃ）は第１スタンド出側における板厚の変化を、（ｄ）は第２スタンド出側における板厚の変化を、（ｅ）は最終スタンドである第５スタンド出側における板厚の変化を、それぞれ示すグラフである。
【図６】従来の圧延中にワークロールシフトを行う板材の冷間圧延方法を実施したときの先進率や張力変動の経時変化を示すグラフであり、（ａ）は第１スタンドにおける先進率の変化を、（ｂ）は第１〜２スタンド間張力の変化を、（ｃ）は第１スタンド入側張力の変化を示すグラフである。
【図７】シフトスタンドの圧延速度と先進率の変化量との関係を、シフト速度をパラメタ−として示したグラフである。
【図８】シフトスタンドの圧延速度と先進率の変化量との関係を、ワ−クロ−ルの表面粗さおよび圧延油の濃度をパラメタ−として示したグラフである。
【符号の説明】
１ ワ−クロ−ル
２ バックアップロ−ル
３ 圧延スタンド
４ 板材
５ 圧延油
６ 圧力調整弁
７ 圧延油供給配管
８ ク−ラントタンク
９ ク−ラントポンプ
１０ ク−ラントヘッダ
２１ ミキサ−
２２ ミキシングタンク
２３ ポンプ
２４ 圧力調整弁
２５ 遮断弁
２６ 遮断弁[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling method in which a work roll is shifted in an axial direction during rolling, and more particularly to a cold rolling method in which a change in sheet thickness does not occur during a work shift.
[0002]
[Prior art]
2. Description of the Related Art When a sheet material is rolled by a continuous rolling mill, in order to reduce an edge drop generated at an end portion of the sheet, rolling is performed by shifting a work roll in an axial direction. This work shift is performed not only for the purpose of reducing the edge drop but also for the work formed by the corner portion of the plate contacting the work. It is also used for the purpose of preventing the occurrence of edge marks on the roll and controlling the shape in the plate width direction.
[0003]
In particular, when the work shift is applied for the purpose of reducing the edge drop, as disclosed in Japanese Patent Publication No. 60-51921, for example, the shape of one end of the work roll is used. Is processed into a taper shape.
[0004]
When rolling by work-roll shift is applied to cold rolling, cold rolling is generally continuous rolling in which a plurality of original coils (coils before cold rolling) are welded and connected one after another. It is necessary to carry out a work shift during rolling, mainly in accordance with the width of the original coil to be rolled.
[0005]
However, if the work shift is performed during rolling, a problem as disclosed in Japanese Patent Application Laid-Open No. 7-100502 occurs. That is, during the work shift, the plate material is formed on the surface of the work roll in a direction perpendicular to the axial direction (the feed of the grinding wheel during the roll grinding). Is skewed with respect to circumferential streaks generated on the roll surface accompanying the rolling, the friction coefficient is increased, and the thickness of the original coil rolled during the work shift is increased. Increase.
[0006]
In order to prevent such behavior, Japanese Unexamined Patent Application Publication No. 7-100502 discloses a method for controlling the rolling speed at a shift speed determined by using at least one of the rolling speed and the surface roughness of the rolling as a control factor. The method of rolling while shifting is disclosed.
[0007]
Regarding the increase in the coefficient of friction which causes such an increase in sheet thickness, a similar report has been made in a rolling method in which the upper and lower rolls are crossed (October 1992, The 43rd Lecture Meeting on Plastic Working) , Lecture Papers II, "Load Characteristics of Cold Cross Rolling of Thin Sheets").
[0008]
The phenomenon in the cross roll rolling is the same as that in the case where the rolled material shifts during rolling, in that the rolled material skews with respect to the grinding line on the surface of the roll.
[0009]
[Problems to be solved by the invention]
However, the above-described conventional technology has the following problems.
[0010]
In other words, the present inventors applied the BISRA-AGC to the stand for performing the shift of the wheel during rolling to control the thickness of the stand while performing the shift of the wheel during rolling. The thickness of the sheet on the exit side of the stand and the thickness on the downstream side were changed.
[0011]
FIG. 5 shows a 5-stand continuous cold rolling mill to which BISRA-AGC is applied as an automatic thickness control means in the first stand, and the sheet material is cooled at a rolling speed of 45 m / min in the first stand. Is a graph showing the behavior of a rolling mill and a rolled material over time when the work of the first stand having a surface roughness of 1 μm and having a surface roughness of Ra is shifted in the axial direction at a shift speed of 2 mm / min. (A) shows the change in the distance between the center of the trunk of the upper and lower wheels of the first stand that performs the wheel shift and the center of the pass line (hereinafter referred to as the "wheel shift position"). (b) shows the change in the rolling load at the first stand, (c) shows the change over time in the sheet thickness on the exit side of the first stand, (d) shows the change in the sheet thickness on the exit side of the second stand, and (e). ) Is the final stand, the fifth stand exit side The change in the definitive thickness is a graph showing respectively.
[0012]
As can be seen from FIG. 5 (b), in the first stand that performs a shift in rolling during rolling, the rolling load increases only during shifting in the roll.
[0013]
The BISRA-AGC (BISRA-type sheet thickness control device) can prevent such an increase in the sheet thickness caused by the increase in the rolling load, and as shown in FIG. The thickness is controlled to be substantially constant.
[0014]
However, even if the plate thickness is kept constant at the first stand for performing the wheel shift, the next plate thickness on the exit side of the second stand is maintained while the wheel shift is performed at the first stand. As shown in FIG. 5D, the thickness of the finished plate on the exit side of the fifth stand, which is the final stand, is reduced by several μm to several μm from the target plate thickness, as shown in FIG. It is smaller by about 10 μm.
[0015]
The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-100502 is for maintaining the output side plate thickness of a stand performing a work shift in a constant manner. There is a problem that it cannot be retained.
[0016]
Incidentally, Japanese Patent Publication No. 60-51921 does not disclose a measure for thickness fluctuation when performing a wheel shift during rolling.
[0017]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to prevent a change in a finished plate thickness when performing a work roll shift during rolling.
[0018]
[Means for Solving the Problems]
The cold rolling method of a plate material for performing a work roll shift during rolling according to the present invention is characterized in that, in a stand to which BISRA-AGC is applied as an automatic thickness control means , a work roll which is arranged vertically above and below is provided. In shifting in the respective axial directions during rolling, at least one of the concentration of the rolling oil, the supply amount, and the emulsion particle size is determined during the period from the start to the end of the work shift. Rolling is performed with a change in comparison with the time of steady rolling in which rolling is not performed.
In addition, when shifting the vertically arranged work rolls in the respective axial directions during the rolling, the concentration of the rolling oil, the supply amount, and the emulsion from the start to the end of the work shift shift. By changing at least one factor of the grain size as compared with that at the time of steady rolling without performing the work shift, the rolling is performed while suppressing the variation of the advanced ratio.
[0019]
Further, when the surface roughness of the work is 0.5 μm or more in Ra, the above cold rolling method is performed.
[0020]
The inventor of the present invention has analyzed in detail the cause of thickness variation when performing a work roll shift during rolling, and has found that the following mechanism is an essential cause. That is, when performing a work roll shift during rolling, the rolled material will be skewed with respect to the grind on the roll surface, a change occurs in the lubrication state of the roll bite, not only the average value of the friction coefficient, Due to the change in the distribution, the neutral point is moved in the roll bite exit side direction, and the increase in the tension between the stands in front of the stand is concluded to be the cause of the thickness variation. .
[0021]
Generally, the lubrication state in the roll bite during cold rolling is such that the lubricating oil film introduced at the bite entrance becomes thinner as the material elongates in the rolling direction, and the contact portion between the roll and the rolled material expands. Will be done. Therefore, at the roll bite inlet, fluid lubrication was dominant, but it is considered that the boundary lubrication area expanded toward the roll bite outlet, and the rolled material was skewed relative to the grinding roll roll. It is believed that the impact of doing so will be closer to the roll bite exit, ie, more affected in the advanced region.
[0022]
FIG. 6A is a graph showing the change with time of the advance rate of the first stand that performs the wheel shift when the wheel shift is performed under the same conditions and timings as those described in FIG. (B) is a graph showing the temporal change of the tension between the first and second stands (the tension between the front stands), and (c) is a graph showing the temporal change of the tension on the first stand entrance side (the rear tension). As described with reference to FIG. 5, despite the fact that the plate thickness on the exit side of the shift stand is kept constant by BISRA-AGC, as shown in FIG. Is confirmed. Further, as shown in FIG. 6C, the tension between the front stands is increased by about 10% as shown in FIG. 6B, although the rear tension is controlled to be substantially constant. I understand.
[0023]
It is a well-known fact that an increase in the tension between the front stands greatly affects the thickness of the exit side plate of the front stand (second stand). It was concluded that this was the mechanism of plate thickness fluctuation when performing work roll shift.
[0024]
That is, the thickness variation that occurs when a work roll shift is performed during rolling is a variation in the advance rate caused by a change in the lubrication state during the work shift. The variation in the finished plate thickness is essentially a shift of the neutral point toward the roll bite exit side due to a change in the lubrication state, that is, a variation in the advance ratio and an increase in the tension between the front stands due to this. This occurs even when the delivery side plate thickness of the shift stand is kept constant by means such as AGC.
[0025]
Such a forward movement of the neutral point is caused by the fact that the rolled material is skewed with respect to the grinding line on the roll surface during the work roll shift, thereby changing the lubrication state, and the rolling speed is reduced. , Shift speed, roll surface roughness and rolling oil viscosity are the main influencing factors.
[0026]
The movement of the neutral point, that is, the fluctuation of the advanced ratio, becomes larger as the rolling speed is slow, the shift speed is high, the roll surface roughness is rough, and the lubricating property of the rolling oil is poor.
[0027]
The graph of FIG. 7 shows that the rolling speed (mpm) of the first stand and the amount of change (%) in the advance rate when the work of the first stand having a surface roughness Ra of 1 μm was shifted during rolling. ) Is shown as the shift speed as a parameter. From the figure, it can be seen that the amount of change in the advance ratio increases as the rolling speed decreases, but also increases as the shift speed increases.
[0028]
The graph of FIG. 8 shows the change in the rolling rate (mpm) of the first stand and the rate of advance (%) when the work of the first stand was shifted at a shift speed of 2 mm / sec during rolling. 2) shows the surface roughness of rolling and the concentration of rolling oil as parameters. From the figure, it can be seen that the variation of the advance ratio increases as the surface roughness of the work becomes rougher and as the rolling oil concentration becomes lower, that is, the lubricity becomes worse.
[0029]
The amount of movement of the neutral point has a large correlation with the amount of change in the tension between the front stands and the amount of change in the plate thickness. In particular, when the surface roughness of the roll is 0.5 μm or more in Ra, the fluctuation of the advanced ratio is remarkable, and as for the rolling oil, the higher the concentration, the larger the supply amount, and the larger the emulsion particle size. , The fluctuation of the advance rate is reduced. By the way, work roll shift is a technique whose main purpose is to control the profile shape in the sheet width direction. In a completely continuous rolling mill, the shift position of the work roll during rolling is determined according to the sheet width of the steel sheet. Need to be changed. In order to reduce a transition region (a longitudinal direction range of a sheet material affected by a thickness shift or the like due to a work shift) caused by changing the shift position, the shift position is changed at a high speed. In addition, it is necessary to reduce the rolling speed. However, it is not practical to limit the shift speed and the rolling speed in order to exert the original function of the work roll shift. In addition, it is possible to reduce the variation of the advance rate by making the roll surface roughness finer, but since the slip between the material and the roll is likely to occur, the rolling reduction per stand is restricted. This is not a good idea because of the inconvenience.
[0030]
In such a situation, it is effective to control the lubrication state as a means for suppressing the fluctuation of the advance rate. That is, the advance rate fluctuation when performing the work roll shift during rolling is reduced as the concentration of the rolling oil is higher, the supply amount is larger, and the emulsion particle size is larger. In addition, by using any of these means, it becomes possible to reduce the thickness variation to a level at which there is no practical problem. However, when using a high-viscosity oil having a viscosity at 40 ° C. of the rolling oil exceeding 100 cst, there is no practical problem without taking such measures.
[0031]
On the other hand, such a concentration of the lubricating oil, an increase in the supply amount, an increase in the emulsion particle size or the use of the high-viscosity oil increase the use amount of the rolling oil. Therefore, during steady rolling, in which the work roll is at a fixed position, the concentration of the lubricating oil, the supply amount, or the emulsion particle size is set lower than during the work shift to reduce the amount of rolling oil used. Should also be reduced.
[0032]
When the rolling speed is high and the shift speed is low, the fluctuation of the advanced ratio and its influence on the fluctuation of the sheet thickness are extremely small, and are at a level that causes no practical problem. According to the study by the present inventors, it has been found that the variation of the advanced ratio becomes large under the condition that the rolling speed in the shift stand is 100 mpm or less and the shifting speed is 0.5 mm / sec or more.
[0033]
By the way, in order to control the thickness variation in tandem rolling, the technology of adjusting the concentration of the rolling oil, the supply amount, the emulsion particle size, etc. is general, but originally from the purpose of controlling the profile in the width direction of the plate. It can be said that a method of adjusting the rolling oil in correspondence with the operation of the work roll shift to be used, in order to prevent the thickness fluctuation caused by the disturbance, has not been seen so far. As a result, it is possible to change the shift position to the target shift position without restricting the shift speed unlike the related art, and it is possible to reduce the amount of change in the plate thickness.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
A cold rolling method for a sheet material in which a work roll shift is performed during rolling according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a piping system diagram when performing this cold rolling method. In this cold rolling method, a plurality of rolling stands 3 (only two stands are shown in FIG. 1) constituted by a pair of upper and lower work rolls 1 and a pair of upper and lower backup rolls 2 are shown. When the pair of upper and lower wheels 1 is shifted in the axial direction during rolling of the plate material 4, the pressure adjusting valve 6 is connected to the rolling oil supply pipe 7 in order to increase the supply amount of the rolling oil 5. It is provided on the way. The rolling oil 5 is supplied from a coolant tank 8 by a coolant pump 9 via a pressure regulating valve 6 to a coolant header 10. The pressure adjusting valve 6 is squeezed to supply the rolling oil 5 at the time of steady rolling in which no work shift is performed during rolling. However, when performing the work shift during rolling, the pressure adjusting valve 6 is used. To increase the supply amount of the rolling oil 5.
[0035]
In this cold rolling method, since the rolling is performed as described above, the lubricated state is maintained well even during the work shift, and the finished plate thickness of the plate material does not change.
[0036]
Next, a cold rolling method for a sheet material in which a work roll shift is performed during rolling according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a piping system diagram when performing this cold rolling method. In FIG. 2, portions common to FIG. 1 are denoted by the same reference numerals, and detailed description of common portions is omitted. In this cold rolling method, in addition to the case of the cold rolling method of the plate material performing the work roll shift during the rolling of the first embodiment, a mixer 21 is provided in the middle of the rolling oil supply pipe 7, Crude oil of rolling oil is supplied to the mixer 21 from the mixing tank 22 by the pump 23 via the pressure adjusting valve 24 and the shutoff valve 25. At the time of steady rolling in which no rolling shift is performed during rolling, the shut-off valve 25 is closed and the rolling oil 5 is supplied only from the coolant tank 8, but the rolling shift is performed during rolling. In some cases, the shut-off valve 25 is opened to supply the rolling oil crude oil to the mixer 21, and the mixer 21 mixes the rolling oil sent from the coolant tank and the rolling oil sent from the mixing tank. And supply it as a highly concentrated rolling oil.
[0037]
The graph of FIG. 3 shows that, under the same conditions and at the same timing as those described with reference to FIGS. 5 and 6, when the walker of the first stand is shifted, the steady rolling is performed without performing the walker shift during rolling. When an equal amount of an emulsion oil (rolling oil) having a crude oil concentration of 3.0% is additionally supplied in addition to an emulsion oil (rolling oil) having a crude oil concentration of 1.5% of the rolling oil supplied at the time. (A) shows the change in the work shift position, (b) shows the change in the plate thickness on the exit side of the first stand, (c) shows the change in the plate thickness on the exit side of the second stand, (d) () Is a graph showing the change in the plate thickness on the exit side of the fifth stand, which is the last stand, and (e) is a graph showing the change in the advanced ratio in the first stand.
[0038]
Also in this cold rolling method, since the rolling is performed as described above, the lubricated state is maintained well even during the work shift, and the finished plate thickness of the plate material does not change.
[0039]
Next, a cold rolling method for a sheet material in which a work roll shift is performed during rolling according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a piping system diagram when performing this cold rolling method. In FIG. 4, portions common to FIG. 2 are denoted by the same reference numerals, and detailed description of common portions is omitted. In this cold rolling method, an emulsion oil (rolling oil) having a lower emulsifier concentration than the emulsion oil (rolling oil) of the coolant tank 8, that is, an emulsion oil (rolling oil) having a large emulsion particle size, is stored in the mixing tank 22. deep. Then, during steady rolling in which no work shift is performed during rolling, the shut-off valve 25 is closed and emulsion oil (rolling oil) is supplied from the coolant tank 8. When a work shift is performed during rolling, the shutoff valve 25 is opened and the shutoff valve 26 is closed, and an emulsion oil (rolling oil) having a large emulsion particle size is supplied from the mixing tank 22.
[0040]
Also in this cold rolling method, since the rolling is performed as described above, the lubricated state is maintained well even during the work shift, and the finished plate thickness of the plate material does not change.
[0041]
【Example】
In order to confirm the effect of the present invention, when the rolling speed, the shifting speed and the surface roughness of the work in the shift stand are variously different, the concentration of the rolling oil, the supply amount and the emulsion particle size at the time of shifting according to the present invention. The variation in the thickness of the final stand at the time of rolling at least one of the above, and at the time of conventional shifting, when rolling with the same rolling oil concentration, supply amount and emulsion particle size as during steady rolling, It was investigated how the amount (μm) changes. Table 1 shows the results.
[0042]
[Table 1]

[0043]
As is clear from Table 1, under the same rolling conditions, it was better to increase the rolling oil concentration, the supply amount, and the emulsion particle size during the work-roll shift by increasing at least one of the rolling oil thickness. It can be seen that the amount is smaller.
[0044]
【The invention's effect】
When performing a work shift during rolling, the lubrication state of the shift stand where the lubrication conditions are poor is increased only while changing the shift position. Can perform tandem rolling.
[Brief description of the drawings]
FIG. 1 is a piping system diagram for explaining a cold rolling method for a sheet material in which a work roll shift is performed during rolling according to a first embodiment of the present invention.
FIG. 2 is a piping system diagram for explaining a cold rolling method for a sheet material in which a work roll shift is performed during rolling according to a second embodiment of the present invention.
FIGS. 3A and 3B are graphs showing changes with time, such as changes in plate thickness and advanced ratio, when the present invention is carried out. FIG. The change in the distance between the center and the center of the pass line, (b) the change in the plate thickness on the exit side of the first stand, (c) the change in the plate thickness on the exit side of the second stand, and (d) the final stand (E) is a graph showing a change in the plate thickness on the exit side of the fifth stand, and (e) is a graph showing a change in the advance rate at the first stand.
FIG. 4 is a piping system diagram for explaining a cold rolling method for a sheet material in which a work roll shift is performed during rolling according to a third embodiment of the present invention.
FIG. 5 is a graph showing time-dependent changes in sheet thickness and the like when a conventional cold rolling method of a sheet material in which a work roll shift is performed during rolling is performed. , (B) shows the change in the rolling load in the first stand, (c) shows the change in the plate thickness on the exit side of the first stand, (d) shows the change in the plate thickness on the exit side of the second stand, and (e). Is a graph showing a change in plate thickness on the exit side of the fifth stand, which is the last stand.
FIG. 6 is a graph showing a temporal change of an advance ratio and a tension variation when a conventional cold rolling method of a plate material performing a work roll shift during rolling is performed, and FIG. FIG. 4B is a graph showing a change, FIG. 4B is a graph showing a change in tension between the first and second stands, and FIG.
FIG. 7 is a graph showing the relationship between the rolling speed of the shift stand and the amount of change in the advance ratio, with the shift speed as a parameter.
FIG. 8 is a graph showing the relationship between the rolling speed of the shift stand and the amount of change in the advance rate, as parameters of the surface roughness of the work roll and the concentration of the rolling oil.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work roll 2 Backup roll 3 Rolling stand 4 Plate 5 Rolling oil 6 Pressure control valve 7 Rolling oil supply piping 8 Coolant tank 9 Coolant pump 10 Coolant header 21 Mixer
22 mixing tank 23 pump 24 pressure regulating valve 25 shutoff valve 26 shutoff valve

Claims (3)

In a stand to which BISRA-AGC is applied as an automatic thickness control means, in order to shift, in the respective axial directions , the vertically arranged work wheels in the respective axial directions during rolling, the work starts from the start of the work shift and ends. Rolling, wherein at least one of the factors of the concentration of the rolling oil, the supply amount and the emulsion particle size is changed in comparison with the time of steady rolling without performing the work shift. A cold rolling method for a sheet material in which a work roll shift is performed. Vertically disposed relative the word - black - Le, upon shift to respective axial direction during rolling, Wa - black - between the Rushifuto start to end, the concentration of rolling oil supply amount and the emulsion at least one factor of the particle size, word - black - Rushifuto by Rukoto compared varied during steady rolling is not performed during rolling and performing rolling by suppressing the variation of forward slip A cold rolling method for plate materials that performs work roll shift. 3. The cold rolling method according to claim 1, wherein the surface roughness of the work roll is 0.5 μm or more in Ra. Rolling method.

Images