JPH1110214A - Method for preventing overload in driving system for rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the prevention of an overload in the driving system for a rolling mill without restriction by a simple method in the calculation for setting each pass of a rolling schedule, which is a technique applied to the rolling mill in which the upper and lower rolls of the rolling mill are rotated at different speeds and related to a method for preventing an overload in the driving system such as a spindle of the rolling mill. SOLUTION: In a preventing method of an overload in the driving system of a rolling mill capable of rolling by varying the number of revolution of upper and lower rolls, the estimating calculation of TAF which is the ratio of a max. torque at the time of biting in rolling which acts on the driving system of the rolling mill to a stational torque at the time of rolling is executed from the set value of a rolling speed at the time of biting in rolling. The estimated value of the max. torque at the time of biting in rolling which is calculated based on the estimating-calculated TAF is compared with the value of the allowable torque of the driving system of the rolling mill and the rolling is executed by adjusting the set value of the rolling speed so that the estimated value of the max. torque at the time of biting in rolling is not higher than the value of the allowable torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique applied to a rolling mill in which upper and lower rolls of a rolling mill rotate at different speeds, and relates to a rolling method for preventing a drive system such as a rolling mill spindle from being overloaded.

[0002]

2. Description of the Related Art In recent years, in rolling of a thick plate or the like, in order to prevent the leading end of a rolled material from warping or curling downward, and to prevent the rolling material from sticking to a table roll, etc. The above-mentioned warpage is corrected by rotating at a different speed to perform rolling. However, the implementation of the different speed rotation causes imbalance in the spindle peak torque conventionally applied uniformly to the upper and lower spindles. The rotation speed of the upper roll and the lower roll, that is, the ratio of the rotation speeds of the upper spindle and the lower spindle, is referred to as a different speed ratio. FIGS. 6A and 6B schematically show how the peak torque is generated when the different speed ratio between the upper spindle and the lower spindle is zero (that is, the same speed).

FIG. 6A shows an upper spindle, and FIG. 6B shows a lower spindle. The horizontal axis in the figure is a time axis, which indicates the time immediately before the rolled material comes off, with the timing of biting the rolled material being zero. The vertical axis indicates the torque. As shown in the figure, when the different speed ratio is zero, the upper and lower spindles show the same behavior, and the peak torque immediately
Tmax appears and thereafter converges to the steady torque Ts. On the other hand, FIGS. 6C and 6D show a case where the speed of the upper spindle is higher as an example of the case of different speed rolling. In this case, as shown, the peak torque Tmax at the upper spindle (c) is much larger than the peak torque Tmax at the lower spindle (d). Conversely, when the speed of the lower spindle is high, it is clear that the peak torque Tmax of the lower spindle is larger, and the illustration is omitted here.

That is, in the case of variable speed rolling, an excessive peak torque is generated by a roll having a higher roll speed. This has made the estimation of the peak torque more difficult, and made it more difficult to prevent the rolling machine from overloading. The ratio between the larger peak torque Tmax and the steady torque Ts is called TAF. Here, for convenience of the following description, this TAF is defined in advance as TAF = Tmax / Ts (1).

[0005] Conventionally, in rolling a thick plate or the like, a pass schedule is calculated before rolling, and a spindle peak torque of a rolling mill is predicted therein. This is because if the spindle peak torque is too large, the drive system such as the spindle and the spindle coupling will be damaged and a large secondary disaster will occur. Therefore, it is attempted to prevent the damage accident by predicting the spindle peak torque. Things.

[0006] Generally, the prediction of the spindle peak torque of a rolling mill is performed as follows: Tg = f (T, Δt, R, W, N, kf, ... etc.) (2) This is performed based on a given prediction formula. Where T
Is the temperature of the rolled material, Δt is the rolling reduction, R is the radius of the work roll, W is the width of the rolled material, N is the number of rotations of the work roll, and kf is the deformation resistance.

However, since it is difficult to accurately give each parameter of the equation (2) such as the temperature T of the rolled material, the error of the spindle peak torque value predicted by the peak torque prediction equation (2) is determined. Is generally large. Therefore, in consideration of safety, the allowable value of the predicted torque was set to a low value, and the failure of the drive system equipment due to the generation of excessive torque was prevented.

For the purpose of improving the accuracy of predicting the spindle peak torque, Japanese Patent Application Laid-Open No. 62-3815 discloses
It is proposed to measure the actual spindle torque value in each rolling pass, calculate the deviation between the measurement result and the predicted value based on equation (2), and correct the torque predicted value in the next pass based on the deviation. ing.

[0009]

However, in this method, since a measured value of the spindle torque is obtained, it is necessary to attach a torque measuring device to the rotating spindle, and the control system becomes very complicated. In addition, since the method is to correct the prediction of the next pass based on the measurement results, there is a problem that the most important predicted value of the first pass of the rolling cannot be corrected. Furthermore, recalculation is performed for each path, and setting is performed again based on the recalculation, so that a load is placed on the control computer, and in some cases, the control system is updated in order to perform them in a short time until the next pass. It must be.

However, the application of the above-mentioned conventional peak torque prediction formula was impossible because the error was large. On the other hand, the steady torque in each pass of the rolling schedule can be calculated and set relatively easily by determining each rolling condition in advance. Further, the present inventors have found that there is a strong correlation between the TAF and the rolling speed, and between the TAF and the steady torque, based on operational experience and experiments.

An object of the present invention is to provide a method for realizing a simple and unrestricted prevention of overloading of a rolling mill drive system in each pass setting calculation of a rolling schedule based on these findings.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for driving a rolling mill by predicting and adjusting a maximum torque at the time of rolling bite acting on a drive system of a rolling mill capable of rolling by changing the number of rotations of upper and lower rolls. In the system overload prevention method, from the rolling speed set value at the time of rolling bite, TAF which is the ratio of the maximum torque at the time of rolling bite acting on the rolling mill drive system and the steady torque at the time of rolling is estimated and calculated. The estimated rolling torque maximum torque value calculated based on the TAF is compared with the allowable torque value of the rolling mill drive system, and the rolling speed is adjusted so that the estimated rolling torque maximum torque value is equal to or less than the allowable torque value. The object is solved by adjusting the set value and rolling.

A method for preventing overload of a drive system of a rolling mill by predicting and adjusting the maximum torque at the time of rolling bite acting on the drive system of a rolling mill capable of rolling by changing the number of rotations of the upper and lower rolls. The TAF is estimated and calculated from the steady-state torque set value at the time of rolling set according to the pass schedule, and the estimated maximum torque at the time of rolling engagement calculated based on the estimated and calculated TAF and the allowable value of the rolling mill drive system. The object is solved by comparing torque values and adjusting the number of rolling passes in the rolling pass schedule to perform rolling so that the estimated maximum torque at the time of rolling engagement is equal to or less than the allowable torque value.

Further, in a method for preventing overload of a drive system of a rolling mill by predicting and adjusting a maximum torque at the time of rolling bite acting on a drive system of a rolling mill capable of rolling by changing the number of rotations of upper and lower rolls, The TAF is estimated from the rolling speed set value at the time of biting, and the estimated maximum torque at the time of rolling calculated based on the estimated TAF is compared with the allowable torque value of the rolling mill drive system, and the rolling bite is calculated. Is set in accordance with the total rolling time from the start to the end of the rolling pass schedule when rolling at the rolling speed set value determined so that the estimated maximum torque value is equal to or less than the allowable torque value, and the rolling pass schedule. The TAF is estimated from the set value of the steady torque during rolling, and the estimated maximum torque at the time of rolling engagement calculated based on the estimated TAF and the rolling mill drive The number of rolling passes in the rolling pass schedule is adjusted by comparing the permissible torque value of the system and adjusting the number of rolling passes in the rolling pass schedule so that the estimated maximum torque at the time of rolling bite is equal to or less than the permissible torque value. This object is achieved by comparing the total rolling time from the start to the end of the schedule and selecting and rolling a rolling pass schedule with a shorter total rolling time.

[0015]

FIG. 4 shows an example of the relationship between the rolling speed and TAF. In FIG. 4, the horizontal axis represents the rolling speed Uin (mpm), and the vertical axis represents the TAF, showing the relationship for each different speed ratio (Δu). The rolling speed is determined by rolling conditions such as the type of thick steel of the thick plate to be rolled. Here, the first invention of the present invention is to prevent the drive system overload of the rolling mill by correcting and determining the rolling speed according to the processing flow A shown in FIG. 1 based on the relationship in FIG.

FIG. 5 shows an example of the relationship between the steady torque and TAF. FIG. 5 shows the steady torque Ts (tm) on the horizontal axis and the vertical axis on the vertical axis.
This figure shows the relationship between TAF and TAF. The steady torque is a value determined by allocating to each pass in accordance with the number of rolling passes, and it is possible to reduce the steady torque in one rolling pass by increasing the number of rolling passes. Here, based on the relationship shown in FIG. 5, the number n of rolling passes and the steady torque Ts determined corresponding thereto are corrected and determined according to the process flow B shown in FIG. 2, thereby preventing the drive system overload of the rolling mill. Is a second invention of the present invention.

Further, the total rolling time Ta when the rolling is performed at the rolling speed determined by the processing flow A in FIG.
And the total rolling time Tb determined by the number of rolling passes determined in the processing flow B of FIG. Performing overload prevention is the third invention of the present invention.

Hereinafter, details of the processing flow will be described step by step. Although only one pass is shown in the process A in FIG. 1, the steady-state torque Ts in all passes is actually determined based on the rolling schedule, and the rolling speed over all passes is obtained based on it. First, an allowable stress value σlim of a driving system such as a rolling mill spindle is obtained in advance based on an analysis method such as a finite element method. Similarly, the calculated maximum stress σm in the case of the calculated maximum torque Tc is also obtained, and the process proceeds to the following steps.

The processing A in FIG. 1 will be described. (Step 1) Set the rolling conditions and set the rolling speed Uin
Set. (Step 2) A steady torque Ts is obtained based on each rolling condition. (Step 3) Based on Fig. 4, TAF is calculated from rolling speed Uin.
Is estimated. (Step 4) The peak torque Tmax which is the maximum torque at the time of rolling engagement is calculated from the TAF and the steady torque Ts.

Tmax = TAF × Ts (3) (Step 5) Generated stress σx at peak torque Tmax
Is calculated from the ratio of the calculated maximum torque Tc to the calculated maximum stress σm by σx = σm × Tmax / Tc (4), and the generated stress σx is estimated and calculated.

(Step 6) Next, the generated stress σx and the allowable stress value σlim are compared. If σlim <σx, go to (Step 7) If σlim ≧ σx, go to (Step 8) (Step 7) Decrease the rolling speed Uin by a constant value a and return to (Step 3). (That is, calculation of Uin = Uin-a is performed.) (Step 8) The rolling speed Uin is finally determined.

Through the above steps, the rolling speed Uin is corrected and finally determined. In each rolling pass, it is possible to reduce the overload on the drive system by performing the rolling with correction based on the rolling speed Uin determined as described above. Here, although the subtraction process of the constant value a is performed in step 7, it is apparent that the same purpose can be achieved by a method of multiplying the constant value smaller than 1.

Next, the processing B in FIG. 2 will be described. The preconditions in this processing are the same as in the case of FIG. 1 described above, and thus are omitted. (Step 11) Each rolling condition is set, and the number of rolling passes n
Set. (Step 12) The steady torque Ts is obtained based on each rolling condition. (Step 13) Based on FIG. 5, the TAF is calculated from the steady torque Ts.
Is estimated.

(Step 14) The peak torque Tmax is calculated from the TAF and the steady torque Ts. Tmax = TAF × Ts (3) (Step 15) Generated stress σx at peak torque Tmax
Is calculated from the ratio of the calculated maximum torque Tc to the calculated maximum stress σm by σx = σm × Tmax / Tc (4), and the generated stress σx is estimated and calculated.

(Step 16) Next, the generated stress σx is compared with the allowable stress value σlim. If σlim <σx, go to (Step 17) If σlim ≧ σx, go to (Step 18) (Step 17) Increase the number n of rolling passes by one and decrease the steady-state torque Ts by a constant value a (Step 13) Return to

(That is, calculation of n = n + 1 and Ts = Ts-a is performed.) (Step 8) The number n of rolling passes is finally determined. Through the above steps, the number n of rolling passes is corrected and finally determined. In each rolling pass, rolling is performed based on the steady torque Ts that is reduced in accordance with the increase in the number of rolling passes determined as described above, thereby making it possible to reduce overload on the drive train.

Next, the processing C in FIG. 3 will be described. (Step 21) Set the rolling conditions and set the rolling speed Uin
And the number n of rolling passes are set. (Step 22) The rolling speed Uin is determined by the process A in FIG. (Step 23) The rolling time Ta in this case is calculated from the rolling speed Uin.

(Step 24) The number n of rolling passes is determined by the processing B in FIG. (Step 25) The rolling time Tb in this case is calculated from the number n of rolling passes. (Step 26) Ta and Tb are compared. If Ta> Tb, go to (Step 28) If Ta ≦ Tb, go to (Step 27) (Step 27) Rolling is performed according to the rolling conditions and rolling speed based on the process A.

(Step 28) Rolling is performed according to the rolling conditions and the number of rolling passes based on the process B. This processing makes it possible to reduce the overload on the drive system while minimizing the total rolling time. In addition, the rolling mill drive system overload prevention method of the present invention can be applied to any rolling mill, such as a rough rolling mill in a hot rolling line, which sets a pass schedule and rotates upper and lower rolls at different speeds. Is obvious.

[0030]

EXAMPLE The present invention was applied to a thick steel plate having a thickness of 9 mm, a width of 4600 mm, and a total of 21 rolling passes, and was rolled. The allowable stress value σlim of the mill drive system (spindle) is 15 kg / mm ² . In addition, the first-pass steady torque Ts was set to 220 t-m based on the above rolling conditions. The initial setting of the rolling speed Uin is
60mpm. The different speed ratio is 30%, which is a fixed value.

An example of an embodiment in which the first invention (Process A) of the present invention is applied will be described. In the first invention (process A) of the present invention, TAF is determined to be 2.9 by applying FIG. 4 from step 3 of FIG. Therefore, Tmax becomes Tmax = TAF × Ts = 2.9 × 220 = 638 (tm).

The ratio of σm / Tc is determined to be 0.0279 by another calculation, and from step 5, σx is determined as σx = 0.0279 × 638 = 17.8 Kg / mm ² . However, in step 6, since this value exceeds the value of σlim (15 kg / mm ² ), the process proceeds to step 7, where Uin = 60−5 = 55 (mpm) is given. (Here, 5 is given as the constant value a.) Next, at this rolling speed 55 (mpm), loop processing is performed by looping again from step 3 and calculating again, and finally the rolling speed 30 (mpm) is obtained. mpm) when σx = 14.4Kg / mm ²
Σ lim = 15 kg / mm ² , and the rolling speed 30 (mpm) is finally determined in step 8.

An example of an embodiment when the second invention (Processing B) of the present invention is applied will be described. In the second invention (process B) of the present invention, TAF is obtained as 2.82 by applying FIG. 5 from step 13 in FIG. Therefore, Tmax becomes Tmax = TAF × Ts = 2.82 × 220 = 620 (tm).

The ratio of σm / Tc is determined to be 0.0279 by another calculation, and from step 5, σx is determined as σx = 0.0279 × 620 = 17.3 Kg / mm ² . However, since this value exceeds the value of σlim (15 kg / mm ² ) in step 6, the process proceeds to step 7, where n = n + 1 = 21 + 1 = 22 (pass) Ts = Ts−a = 220−50 = 170 ( tm). (Here, 50 is given as the constant value a.) Next, loop processing is performed by repeating the loop from step 13 onward with the number of passes n and the steady torque Ts, and finally the number of passes 22 (Pass), steady torque 170 (tm)
Σx = 14.5Kg / mm ^2, and the in step 8 becomes fall below σlim = 15Kg / mm ² rolling passes number 22 (path) is finally determined when.

An example of an embodiment in which the third invention (process C) of the present invention is applied will be described. The third invention (processing C) of the present invention compares the rolling processing time required for each of the first invention and the second invention, and in the above example, in the first invention (processing A), Since the rolling speed is 30 (mpm), the total rolling time is 8 minutes and 20 seconds. In the second invention (process B), the total number of rolling passes is 22 (passes), so that the total rolling time is 8 minutes and 25 seconds. Therefore, in this case, the first invention (process A) is selected, and the rolling process is performed.

As a result of preventing overloading based on the method exemplified above, downtime of 10 hours or more, which has been occurring once every two years until now (due to replacement work due to breakage of spindle coupling etc.) Was completely eliminated. In addition, it has become possible to reduce the maintenance work for replacing the rolling roll fork, which occurs once every three months.

[0037]

According to the present invention, while controlling warpage by variable speed rolling,
At the same time, overload of the rolling mill drive system can be prevented, and downtime due to drive system troubles can be prevented.

[Brief description of the drawings]

FIG. 1 is a processing flowchart of a rolling mill drive system overload prevention method to which a first invention of the present invention is applied.

FIG. 2 is a processing flowchart of a rolling mill drive system overload prevention method to which the second invention of the present invention is applied.

FIG. 3 is a processing flowchart of a rolling mill drive system overload prevention method to which the third invention of the present invention is applied.

FIG. 4 is a diagram showing the relationship between the rolling speed and TAF.

FIG. 5 is a relationship diagram between a steady torque and TAF.

FIG. 6 is a schematic diagram showing generation of steady torque and peak torque in a spindle.

Claims (3)

[Claims] 1. A method for preventing overload of a drive system of a rolling mill by predicting and adjusting a maximum torque at the time of rolling bite acting on a drive system of a rollable rolling mill by changing the number of rotations of upper and lower rolls of the rolling mill. In the above, the TAF, which is the ratio of the maximum torque at the time of rolling engagement and the steady torque during rolling, acting on the rolling mill drive system is estimated from the rolling speed set value at the time of rolling engagement, and calculated based on the estimated and calculated TAF. The rolling torque setting value is compared with the allowable torque value of the rolling mill drive system, and the rolling speed set value is adjusted so that the rolling bite maximum torque estimate value is equal to or less than the allowable torque value. A method for preventing overload of a drive system of a rolling mill, characterized in that rolling is performed. 2. A method for preventing an overload of a drive system of a rolling mill by predicting and adjusting a maximum torque at the time of rolling bite acting on a drive system of a rolling mill capable of rolling by changing the number of rotations of upper and lower rolls of the rolling mill. In the above, TAF from the steady torque set value at the time of rolling set corresponding to the rolling pass schedule
Is calculated, and the estimated maximum torque during rolling engagement calculated based on the estimated and calculated TAF is compared with the allowable torque value of the rolling mill drive system, and the estimated maximum torque during rolling engagement is determined as the allowable torque. A method for preventing overload of a drive system of a rolling mill, wherein rolling is performed by adjusting the number of rolling passes in the rolling pass schedule so as to be not more than a value. 3. A method for preventing an overload in a drive system of a rolling mill by predicting and adjusting a maximum torque at the time of rolling engagement acting on a drive system of a rolling mill capable of rolling by changing the number of rotations of upper and lower rolls of the rolling mill. In the above, the TAF is estimated from the rolling speed set value at the time of rolling engagement, and the estimated TA is calculated.
The rolling speed determined by comparing the estimated maximum torque during rolling bite calculated based on F with the allowable torque value of the rolling mill drive system and determining that the estimated maximum torque during rolling bite is equal to or less than the allowable torque value. The TAF is estimated and calculated from the total rolling time from the start to the end of the rolling pass schedule when rolling is performed at the set value and the steady torque set value at the time of rolling set in accordance with the rolling pass schedule. In the rolling pass schedule, a maximum torque estimated value at the time of rolling bite calculated based on the allowable torque value of the rolling mill drive system is compared with the estimated maximum torque value at the time of rolling bite to be equal to or less than the allowable torque value. Adjust the number of rolling passes and compare the total rolling time from the start to the end of the rolling pass schedule when rolling with the number of rolling passes. Rolling over a rolling mill by selecting a rolling pass schedule having a shorter total rolling time.