JP2010214453A - Method of deciding tuning rate in cold rolling process and cold rolling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of deciding a tuning rate in a cold rolling process by which the tuning rate of every rolling stand for rolling a material to be rolled at a stable sheet thickness without being affected by the effect of tension vibration of a rolling stand when rolling the material to be rolled with a continuous cold rolling mill is surely determined by a simple calculating method. <P>SOLUTION: The method comprises: a first step where the deviation of the rotational speed of a motor during rolling the material to be rolled; a second step where the speed deviation of the circumferential speed of a roll is calculated from the deviation of the roll speed and, further, the variance of tension until the material to be rolled reaches the next rolling stand 11-15 is calculated from the deviation of the roll speed; a third step where the variance of the tension correcting term is calculated by using the variance of the tension and the variance of load is calculated from the variance of the tension correcting term; and a fourth step where the tuning rate for every rolling stand for controlling the variance of the sheet thickness to an proper range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a tuning rate (gain) for each rolling stand in a continuous cold rolling mill that controls the thickness of a material to be rolled by performing variable mill rigidity control for controlling a roll gap for each of a plurality of rolling stands. ) To determine the tuning rate in the cold rolling process and to determine the thickness of the material to be rolled using the calculated tuning rate (gain), and cold rolling the material to be cold rolled The present invention relates to a rolling method.

  Conventionally, when rolling a material to be rolled in the cold rolling process, the thickness of the material to be rolled is controlled, and as a typical method, the thickness deviation on the exit side of the rolling stand is measured with a measuring instrument. AGC control for measuring and changing the roll gap and roll speed is known, and is generally implemented in the cold rolling process.

  However, in this AGC control, since there is a distance from the operation end to the measuring instrument, a delay time occurs, and it becomes difficult to perform sheet thickness control immediately after the start of rolling or when the rolling speed is low. As a means for compensating for this, the mill stiffness variable control with a small delay time is implemented. In the mill stiffness variable control, the plate thickness variation is represented by a component accompanying the load variation and a component due to the operation amount of the roll gap, and control is performed to bring the plate thickness variation as low as possible to zero.

That is, when the load variation is ΔP, the mill rigidity is M, and the variation amount of the roll gap is ΔS, the plate thickness variation amount Δh can be expressed by the following relational expression (1). (Note that Δ indicates the amount of variation, and hereinafter, in the present specification, all the values that vary are denoted by Δ.)
Δh = (ΔP / M) + ΔS (1)
Here, (ΔP / M) corresponds to an apparent roll gap change amount accompanying a load change. From this relational expression (1), it can be understood that if the roll gap variation ΔS is − (ΔP / M), the plate thickness variation ΔP can theoretically be zero. However, in the mill stiffness variable control, the tuning rate (gain ) The thickness control based on the following formula (2) is performed using α.
ΔS = −α (ΔP / M) (2)
When this equation (2) is substituted into equation (1), Δh = (ΔP / M) + {− α (ΔP / M)}, and the plate thickness change amount Δh is expressed by the following relational expression ( 3).
Δh = ΔP / M × (1−α) (3)

  As prior art regarding such a mill stiffness variable control using the tuning rate α, for example, proposals described in Patent Documents 1 to 4 have been made.

  Patent Document 1 discloses a technique of adjusting the tuning rate α according to the rolling speed in order to suppress the occurrence of sheet thickness defects due to the rolling speed being stopped or being close to a stopped state. Specifically, the technical content of adjusting the tuning rate α to the range of 0.4 to 0.6 when the rolling speed becomes less than a predetermined speed is described.

  In Patent Document 2, a sheet thickness change amount, a load change amount, and a tension change amount are online in order to suppress the thickness change in the longitudinal direction such as hardness unevenness in a steel strip rolled by a cold rolling mill. A technique is described in which a correlation function is calculated, and a reduction position correction amount is calculated from a rolling load change amount according to the value of the correlation function.

  In Patent Document 3, in order to suppress fluctuations in the plate thickness and improve the plate thickness accuracy, the rolled material is wound in a coil shape, and is in the state where it is in a winding / rewinding device, from the outermost side where there is hardness unevenness. A technique is described in which the tuning rate of the mill stiffness variable control at the time of rolling between the part at the predetermined position and the part at the predetermined position from the innermost side is made larger than the tuning rate at the steady portion.

  In Patent Document 4, in order to remove the declination of a continuous rolling mill equipped with a hydraulic reduction device controlled by the BISRA AGC mode, dynamic adjustment is performed using the tuning rate of the BISRA AGC mode that is variable according to the rolling speed. A technique is described in which a hydraulic reduction device is controlled so as to suppress a tilt component in a low speed region of a backup roll by obtaining a mill stiffness coefficient as a function of a rolling speed.

Japanese Patent Laid-Open No. 2007-118048 JP 2003-136116 A Japanese Patent Laid-Open No. 10-272507 Japanese Patent Laid-Open No. 7-16626

  When rolling high-strength steel sheets with a continuous cold rolling mill, the phenomenon that the amount of tension vibration increases as the latter stage stand occurs. As a result, the thickness of the material to be rolled varies due to the vibration of the rolling stand. The problem that occurs is occurring.

  The present invention has been made to solve the problem, and when rolling the material to be rolled in a continuous cold rolling mill, the material to be rolled has a stable thickness without being affected by the tension vibration of the rolling stand. It is an object of the present invention to provide a method for determining a tuning rate in a cold rolling process, in which a tuning rate for each rolling stand for rolling can be reliably obtained by a simple calculation method. Another object is to provide a cold rolling method capable of rolling a material to be rolled as a stable plate thickness without being affected by the tension vibration of the rolling stand, using the tuning rate obtained by the determination method. To do.

  The invention according to claim 1 is a continuous cold rolling mill that controls the thickness of a material to be rolled by performing variable mill rigidity control for controlling a roll gap for each of a plurality of rolling stands. A method for determining a tuning rate in a cold rolling process for determining a tuning rate (gain), the first step of collecting a deviation in the rotational speed of a motor during rolling of a material to be rolled, and the rotational speed of the motor The second step of calculating the speed deviation of the roll peripheral speed from the deviation, and further calculating the tension change amount from the roll speed deviation to the next rolling stand of the material to be rolled, and the tension correction using the tension change amount The third step of calculating the amount of change in the term and calculating the amount of change in the load from the amount of change in the tension correction term, and the rolling stand for setting the amount of change in the plate thickness within the appropriate range from the amount of change in the load. A tuning rate cold method of determining tuning rate in the rolling process, characterized in that consists of a fourth step of calculating (gain).

  The invention according to claim 2 controls the thickness of the material to be rolled by controlling the roll gap for each of a plurality of rolling stands using the tuning rate (gain) obtained by the method for determining the tuning rate according to claim 1. And performing a cold rolling on the material to be rolled.

  According to the method for determining the tuning rate in the cold rolling process according to claim 1 of the present invention, the rolling material is rolled in a continuous cold rolling mill, and is stable without being affected by the tension vibration of the rolling stand. The rolling rate of each rolling stand for rolling the material to be rolled as the plate thickness can be obtained reliably by a simple calculation method, and the roll gap for each of the multiple rolling stands can be controlled with the tuning rate. Thus, in the continuous cold rolling mill, it is possible to suppress the occurrence of the problem that the tension vibration propagates to the subsequent stage stand, and as a result, it is possible to suppress the occurrence of the plate thickness fluctuation of the material to be rolled.

  According to the cold rolling method of claim 2 of the present invention, it is possible to suppress the occurrence of the problem that the tension of the rear stand vibrates in the continuous cold rolling mill, and as a result, the thickness variation of the material to be rolled. Can be suppressed.

It is a schematic diagram showing an outline of a continuous cold rolling mill that employs the tuning rate determination method of the present invention and performs cold rolling. It is a graph which shows the board thickness fluctuation | variation of the to-be-rolled material in each rolling stand in an Example.

  In continuous cold rolling mills that control the thickness of the material to be rolled by implementing variable mill stiffness control that controls the roll gap for each of multiple rolling stands, the problem is that the plate thickness vibration amount increases as the subsequent stage stands. Therefore, the present inventors investigated and examined the cause of the occurrence of the problem.

  It is known that the deformation resistance of the base plate influences as a cause of the plate thickness fluctuation, but as a result of intensive studies by the present inventors, the tension vibration caused by the speed deviation generated in the low rotation region of the motor In particular, it has been found that the tension between the first stand and the second stand in particular has the most influence as the cause of the plate thickness fluctuation.

  Mainly due to the deformation resistance fluctuating due to the tension vibration on the entry side of the second rolling stand, the thickness variation of the material to be rolled has occurred. It was confirmed that vibrations with the same frequency were generated and further plate thickness fluctuations occurred.

  The tuning rate (gain) conventionally used so far is a tuning rate set on the assumption that the influence of the plate thickness vibration on the entry side of the first rolling stand is large. If the roll gap is controlled for each of the plurality of rolling stands, it is impossible to avoid the occurrence of the problem that the tension vibration propagates and the plate thickness vibration amount becomes larger as the latter stand and the occurrence of plate thickness fluctuation.

  Therefore, in order to find a method for determining the tuning rate that takes these into consideration, the present inventors have further intensively studied and studied. As a result, by determining the tuning rate (gain) by the method described below, fluctuations in the thickness of the material to be rolled can be suppressed, and at the same time, the rear stage stand vibrates in the continuous cold rolling mill. It was found that this phenomenon can be suppressed, and the present invention has been completed.

  Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.

  FIG. 1 is a schematic diagram showing an outline of a continuous cold rolling mill 10 that employs the tuning rate determination method in the cold rolling process of the present invention and performs cold rolling. This continuous cold rolling mill 10 is configured by continuously arranging a plurality of rolling stands 11 to 15 (five units # 1 to # 5 in FIG. 1) at regular intervals. The material 70 to be rolled fed from the arrow A direction to the continuous cold rolling mill 10 is sequentially cold-rolled by the rolling stands 11 to 15.

  Each of the rolling stands 11 to 15 includes a pair of rolling rolls 21 to 25 that roll the rolled material 70 and a thickness gauge 31 to measure the thickness of the rolled material 70 that is rolled by the rolling rolls 21 to 25. 35 and load meters 41 to 45 for measuring the rolling load, respectively, and tension meters 51 to 55 for measuring the tension of the material 70 to be rolled are provided between the rolling stands 11 to 15.

  The continuous cold rolling mill 10 is configured to be capable of variable mill rigidity control, and a rolling mechanism that adjusts the roll gap of the paired rolling rolls 21 to 25 for each of the rolling stands 11 to 15. 61 to 65 are provided, and a control unit 80 that drives and controls each of the reduction mechanisms 61 to 65 is provided. The control unit 80 controls the roll gap with a predetermined tuning rate (gain) α with respect to the apparent roll gap change amount accompanying the change in rolling load. The control unit 80 does not necessarily have to be integrated and controlled as the entire continuous cold rolling mill 10 as shown in FIG. 1, and is provided individually for each of the rolling stands 11 to 15. Control part 80 Each rolling stand 11-15 may be constituted so that it may be controlled individually.

  As described above, the material 70 to be rolled is cold-rolled using the continuous cold rolling mill 10 shown in FIG. 1, and the tuning rate (gain) α for each of the rolling stands 11 to 15 is as follows. It can be determined by performing calculations from the first step to the fourth step described in (1).

  In the first step, a rotational speed deviation (rps) of a motor (not shown) during the rolling of the material 70 is collected. This rotational speed deviation can be obtained from the formula: actual rotational speed / designated rotational speed x rated rotational speed of the motor.

In the second step, first, the speed deviation (mm / s) of the roll peripheral speed is obtained by calculation from the rotational speed deviation (rps) of the motor obtained in the first step. Specifically, the speed deviation (mm / s) of the roll peripheral speed can be obtained from the following equation (4).
Roll peripheral speed deviation (mm / s) = Motor rotational speed deviation (rps) × Gear ratio × Roll diameter (mm) × π (4)

Next, using the speed deviation (mm / s) of the roll peripheral speed obtained from Equation (4), the amount of change in tension Δtb from the following Equation (5) until the material to be rolled reaches the next rolling stand. Calculate
Δtb = E / L∫ (ΔVout) dt (5)
In the above equation, E is the Young's modulus, 21000 kg / mm ² , L is the distance (mm) between the centers of the rolling stands, 4600 mm in the embodiment shown in FIG. 1, and ΔVout is the speed deviation of the roll peripheral speed obtained previously. (Mm / s) is shown respectively.

In the third step, first, the tension correction term change amount ΔZ is obtained by calculation using the tension change amount Δtb obtained in the second step. Generally, the tension correction term Z is expressed as Z = 1− (0.7 × Δtb + 0.3 × tf) / K. Of these, when only the fluctuation of the entry side tension is extracted, the tension correction term change amount ΔZ can be obtained from the following equation (6).
ΔZ = 0.7 × Δtb / K (6)
In the above equation, Δtb is the amount of change in tension on the input side (kg / mm ² ), tf is the tension on the output side (kg / mm ² ), and K is the deformation resistance (kg / mm ² ).

Next, the load change amount ΔP (kg) is calculated from the following equation (7) using the tension correction term change amount ΔZ obtained from the equation (6).
ΔP = B × K × ΔZ × Ld × Qf (7)
In the above equation, B is the sheet width (mm) of the material to be rolled, Ld is the contact length (mm) in the rolling direction between the material to be rolled and the rolling roll, and Qf is a function of the rolling force.

The plate thickness change amount Δh (mm) can be obtained by substituting the load change amount ΔP (kg) obtained in the third step into the equation (3) described above. Next, the formula (3) is described.
Δh = ΔP / M × (1−α) (3)

The plate thickness variation when the material to be rolled is cold-rolled is this plate thickness change amount Δh (mm), but the maximum allowable plate thickness change amount Δh (mm) P is expressed by equation (3). By substituting into, a lower limit value of the tuning rate α can be obtained. For example, assuming that the maximum allowable thickness variation Δh is 0.02 mm, the lower limit value of the tuning rate α can be obtained by the following equation (8). This is the fourth step.
α ≧ 1-M / ΔP × 0.02 (8)

  By performing each calculation from the first step to the fourth step described above, the tuning rate α for each of the rolling stands 11 to 15 can be determined. By cold-rolling the material to be rolled using the tuning rate α obtained here, it is possible to suppress the occurrence of vibration of the rolling stand and to suppress the occurrence of fluctuations in the sheet thickness of the material to be rolled. it can.

  The material to be rolled was cold-rolled using a continuous cold rolling mill comprising five rolling stands with a distance between the stands of 4600 mm. The original sheet thickness of the material to be rolled used in the test was 2.3 mm, the target thickness of the material to be rolled after the cold rolling was 1.4 mm, and the sheet width of the material to be rolled was 1000 mm. Further, the mill constant (mill rigidity) M was set to 500 ton / mm, and the calculation from the first step to the fourth step was performed to obtain the tuning rate α. The tuning rate α was determined so that the plate thickness variation Δh was within 0.02 mm. In addition, cold rolling of the material to be rolled under conventional conditions was also performed.

  The test results are shown in FIG. # 1 to # 5 indicate the first to fifth rolling stands, respectively, and the bar height indicates the thickness variation at each rolling stand. Specifically, using the tuning rate α calculated by applying the present invention, the height of the right bar is calculated by applying the present invention, and the height of the right bar is calculated by applying the present invention. The plate | board thickness fluctuation | variation of the invention example which rolled the to-be-rolled material is each shown.

  According to the test results shown in FIG. 2, it can be seen that the plate thickness variation at each rolling stand is smaller in the invention example than in the conventional example, and the occurrence of the plate thickness variation of the material to be rolled can be suppressed. In addition, in the example of the invention, the occurrence of plate thickness fluctuations can be suppressed, so that the vibration of the rolling stand can also be suppressed.

DESCRIPTION OF SYMBOLS 10 ... Continuous type cold rolling mills 11-15 ... Rolling stands 21-25 ... Roll rolls 31-35 ... Thickness gauges 41-45 ... Load gauges 51-55 ... Tensile gauge 60 ... Reduction mechanism 70 ... Rolled material 80 ... Control unit

Claims (2)

Determine the tuning rate (gain) for each rolling stand in a continuous cold rolling mill that controls the thickness of the material to be rolled by performing mill stiffness variable control that controls the roll gap for each of the plurality of rolling stands. For determining the tuning rate in the cold rolling process for
A first step of collecting a rotational speed deviation of the motor during rolling of the material to be rolled;
A second step of calculating a speed deviation of the roll peripheral speed from the rotational speed deviation of the motor, and further calculating a tension change amount from the roll speed deviation to the next rolling stand of the material to be rolled;
A third step of calculating a tension correction term change amount using the tension change amount, and calculating a load change amount from the tension correction term change amount;
Determination of the tuning rate in the cold rolling process characterized by comprising a fourth step of calculating a tuning rate (gain) for each rolling stand for making the plate thickness change amount within an appropriate range from the load change amount. Method.   Using the tuning rate (gain) obtained by the tuning rate determination method according to claim 1, the roll gap is controlled for each of a plurality of rolling stands to control the thickness of the material to be rolled, and the material to be rolled is cold A cold rolling method characterized by rolling.

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