JP2540165B2 - Front and back color tone control device for rolled material - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a front and back surface color tone control device for rolled material, and in particular,
The present invention relates to a front and back surface color tone control device for a rolled material suitable for use in controlling the color tone of the front and back surfaces of a rolled material such as a steel strip affected by a pair of upper and lower rolling rolls in a tandem cold strip mill.

[Prior art]

In general, a change in color tone between the front and back surfaces of a rolled material in a tandem cold strip mill, that is, a difference in color tone is often caused by a difference in roughness of a roll surface of a rolling roll and a lubrication state of rolling oil on the roll surface. The occurrence of the difference in the roughness of the roll surface is prevented by managing the roll change timing based on the empirically determined rolling tonnage.

[Problems to be Solved by the Invention] However, the occurrence of the color tone difference due to the lubrication state of the rolling oil or the like has not yet been sufficiently studied, and accordingly, the color tone of the rolled steel strip is uniform. The reality is that it is difficult to do so. That is, in the tandem cold strip mill, if the lubrication state between the work roll and the steel strip changes for some reason during rolling, the difference in color tone density (color tone difference) on the surface of the steel strip.
Occurs, and the product after rolling becomes a defective product. This color difference on the surface of the steel strip occurs in the longitudinal direction of the steel strip as it is rolled and also between the front and back surfaces of the steel strip. In particular, since cold tandem strip mills roll at high speed, the occurrence of the color difference on the surface of the steel strip can be detected only after the rolling is finished, and the steel strip having the color difference is a defective product as it is. There is a problem that it has to be. Further, in general, when it is attempted to detect whether or not the color tone is abnormal by a sensor, it is one of the difficult tasks to determine which sensor is used and how to determine the abnormality.

[Object of the Invention]

The present invention has been made in view of the above conventional problems, focusing on the relationship between the occurrence of a color difference between the front and back surfaces and the work roll drive current, and the relationship between the work roll drive current and the spindle torque of the work roll. However, it detects abnormalities in rolling oil lubrication by detecting torque, and accurately detects abnormalities in color tone without using a so-called color tone sensor or its analysis device. It is an object of the present invention to provide a front and back surface color tone control device for a rolled material, which can prevent the color tone difference between the steel strip and the color tone difference between the front and back surfaces of the steel strip in the longitudinal direction.

[Means for solving problems]

The present invention provides a pair of work rolls arranged opposite to each other, by a mechanical-tight rolling mill driven by a single motor, a front and back surface color tone of a rolled material during bite rolling while lubricating the rolled material. In the control device, as shown in FIG. 1 of the essential structure, a torque detecting means for respectively detecting the torque of the spindle of the pair of work rolls, and a torque value obtained by dividing the difference between the detected torques by the average value of the detected torques. By providing a means for calculating the deviation and a flow rate control means for changing the flow rate of the rolling oil supplied to the work roll when the calculated torque value deviation deviates from the predetermined upper and lower limit values, It achieves the purpose.

[Action]

The present invention was made based on the following findings. FIG. 2 shows the relationship between the speed command of the work rolls during rolling and the motor current values of the upper and lower work rolls in the electret-tight rolling mill in which the upper and lower work rolls of the rolling mill are driven by different motors. Is shown. As is clear from FIG. 2, when accelerating the rolling mill, a large work roll drive current is required, and conversely, when decelerating the rolling mill, the work roll drive current may decrease. I understand. Especially when the rolling mill is decelerated, a reverse current sometimes flows. Further, when rolling at a constant speed, the work roll drive current is also almost constant. Further, the work roll drive currents of the upper and lower sides are almost the same, and there is almost no difference in the drive current values. However, as indicated by reference symbol A in FIG. 2, the upper and lower work roll drive current values may greatly differ during rolling for some reason. In the area indicated by reference sign A, the work roll drive current value of the lower work roll increases, and at this time, it is considered that lubrication abnormality has occurred in the lower work roll. The present inventors have found that there is a strong correlation between the abnormal occurrence of the work roll drive current and the occurrence of the color difference of the steel strip. That is, the relationship between the drive current value difference between the upper and lower work rolls and the defective product occurrence rate due to the color tone difference of the steel strip was investigated.
The results shown in the figure were obtained. As is clear from this survey result, the difference between the drive current values of the upper and lower work rolls
If it exceeds 10%, the defective product rate due to the difference in color tone is high. This knowledge is a method of driving the upper and lower work rolls by separate motors, respectively, but between the motor drive current Im and the work roll spindle torque τ,
There is a relationship as shown in equation (1), and the two are in a proportional relationship. τ = k · φ · I _m (1) where k · φ is a constant that depends on the field of the motor. Since the motor torque and the motor current have the relationship as shown in the formula (1), the above knowledge can be applied to a so-called mechanical tight type rolling machine in which the upper and lower work rolls are rolled by one motor. it is conceivable that. That is, the spindle torque of the upper and lower work rolls (rolling torque) is detected by means such as attaching strain gauges to the spindles of the upper and lower work rolls, and the difference between the detected torques is divided by the average value of the detected torques. The torque value deviation is calculated, and when the calculated torque value deviation deviates from the predetermined upper and lower limit values, if the flow rate of the rolling oil supplied to the work roll is changed, as a result, a so-called color tone sensor, It is possible to prevent color difference between the front and back of the steel strip and color difference between the front and back of the steel strip in the longitudinal direction with a simple configuration without using such an analyzer. Like

【Example】

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 4, a cold tandem mill line 10, which is an object of the present invention, rewinds a steel strip 12 and pays it out to a tandem mill 18 in the next process, and a payoff reel 14. A tandem mill 18 for rolling the returned steel strip 12 from a plurality of rolling stands 16 and a tension reel 20 for winding the steel strip 12 rolled by the tandem mill 18.
A rolling oil supply device 22 for supplying a rolling oil such as a lubricating oil to the front and back surfaces of the steel strip 12 rolled by each of the stands 16, and a mill master control device for controlling the tandem mill 18 and the rolling oil supply device 22. 24 and. Each stand 16 of the tandem mill 18 includes a pair of upper and lower work rolls 26A and 26B, and rolling is performed by rolling the pair of upper and lower work rolls 26A and 26B onto the steel strip 12. As shown in FIG. 6, the work rolls 26A and 26B are connected to a mechanical tight gear 51 via spindles (shfts) 54 and 55, respectively. This mechanical tight gear 51 is connected to one motor 28.
That is, the upper and lower work rolls 26A and 26B are mechanically rotated at the same rotation speed. Also, the motor 28
Is controlled by the speed control device 30 so as to have a predetermined rotation speed. The speed control device 30 includes a speed control rotation 32 and a thyristor 34.
And a speed detector 36 including a pulse generator (PLG) installed in the roll driving motor 28,
A signal from the speed detector 36 is fed back to the speed signal output from the mill master control device 24 to control the rotation speed of the roll driving motor 28. The rotation speed command to the speed control device 30 is output from the mill master control device 24. The mill main controller 24 controls the rotation speed of the work rolls 26A and 26B of each stand 16 for each stand.
16 In order to control according to the reciprocal of the plate thickness on the delivery side, the rotation speed command of the work rolls 26A, 26B is calculated based on the reduction rate, and this rotation speed command is output to the speed control device 30. Has been done. The rolling oil supply device 22, the work rolls 26A, 26B
Spray head 38 for spraying rolling oil onto the steel strip 12 that is bitten by, a flow control valve 40 for controlling the flow rate of the rolling oil supplied to the spray head 38, and the spray head 38
Feeder pump that supplies rolling oil from rolling oil tank 42 to
44 and. The mill main controller 24 outputs a rolling oil supply amount command to the rolling oil supply device 22, the flow rate control valve 40 and the feeder pump 42 are controlled based on the supply amount command, and a predetermined amount of rolling oil is supplied. Is supplied to the steel strip 12. The rolling oil supply amount command of the mill master control device 24 is basically a value proportional to the line speed of the tandem mill 18, and thus the rolling oil is basically controlled and supplied according to the line speed. Will be done. The mill master control device 24 controls the work rolls 26
Torque sensor 5 installed on spindles 54 and 55 of A and 26B
Calculate the torque value deviation by dividing the difference in the detected torque by 2, 53 by the average value of the detected torque, and if the calculated torque value deviation deviates from the predetermined upper and lower limit values, work rolls 26A, 26B Is configured to increase or decrease the flow rate of the rolling oil supplied to. Further, the mill master control device 24 is constantly fed back with detection signals such as current value, voltage value, tension between stands, etc. of the roll driving motor. The color tone control (rolling oil flow rate control) based on the detected torque values of the work roll spindles 54 and 55 in the mill main controller 24 is performed according to the procedure shown in FIG. First, in step 100, the torque value τ _U of the spindle 54 of the upper work roll 26A is detected. Next, in step 102, the torque value τ _L of the spindle 55 of the lower work roll 26B is detected. Next, in step 104, the torque value deviation τα is calculated from the relationship of the following equation based on the torque values τ _U and τ _L detected in the above steps 100 and 102. _{τα = (τ U -τ L)} / {(τ U + τ L) / 2} ......
(2) In the above equation (2), the torque value difference τ _U −τ _L is calculated as the torque value τ.
_The torque value deviation τα is obtained by dividing by the average value of _{U 1} and τ _L. By the processing of this step 104, it is possible to detect the load sharing state of the roll driving motors 28A and 28B. Next, in step 106, it is determined whether or not the torque value deviation τα calculated in the above step 104 is larger than the upper limit value α (= 0.1). When it is determined in step 106 that the torque value deviation τα is larger than the upper limit value α, it is determined that the color tone abnormality has occurred on the upper work roll 26A side, and the process proceeds to step 108. In step 108, a rolling oil correction amount is determined based on the torque value deviation τα. For example, the rolling oil correction amount is set to a value that increases the rolling oil supplied to the upper work roll side by 10%. Next, in step 110, an operation of changing the rolling oil flow rate is performed based on the rolling oil correction amount obtained in the above step 108. Next, the process proceeds to step 112, and after a predetermined time has passed, the process returns to step 100 described above. If it is determined in step 106 that the torque value deviation τα is less than or equal to the upper limit value α, the upper work roll 26
When it is determined that the color tone abnormality has not occurred on the A side, the process proceeds to step 114. In step 114, it is determined whether the torque value deviation τα obtained in the above step 104 is smaller than the lower limit value β (= −0.1). In this step 104, when it is determined that the torque value deviation τα is smaller than the lower limit value β,
It is judged that the color tone of the lower work roll 26B side is abnormal, and step 1
Proceed to 16. At step 116, the rolling oil correction amount is determined based on the torque value deviation τα. For example, the rolling oil correction amount is set to a value that increases the rolling oil supplied to the lower work roll side by 10%. Next, in step 118, the rolling oil flow rate is controlled so that the rolling oil correction amount obtained in step 116 is obtained. Next, the process proceeds to step 112, and returns to the step 100 described above after a lapse of a certain time. If the torque value deviation τα is determined to be equal to or larger than the lower limit value β in the above step 114, it is determined that no color tone abnormality has occurred on the lower work roll 26B side, and the process proceeds to step 120. In step 120, the rolling oil flow rate is maintained as it is without determining the rolling oil correction amount. Next, the process proceeds to step 112, and after a lapse of a certain time, the process returns to step 100 described above. According to the present embodiment, the torque values τ _U and τ _L of the roll driving spindle torques 54 and 55 of the upper and lower work rolls 26A and 26B are detected, and the torque value deviation based on these detected torque values τ _U and τ _L. τα is calculated, and based on the calculated torque value deviation τα, it is determined whether color tone abnormality has occurred on the upper work roll 26A side or the lower work roll 26B side, and the rolling oil flow rate is adjusted based on this determination result. By doing so, a uniform color tone can be obtained. As a result, it is possible to prevent a color tone difference between the front and back surfaces of the steel strip and a color tone difference between the front and back surfaces in the longitudinal direction. That is, since the abnormality of the color tone state is determined based on the detected torque value of the roll driving spindle, it is possible to easily and accurately determine the color tone state without using a color tone sensor or an analyzer thereof. Since an abnormality can be detected, and when there is an abnormality in the color tone state, it is dealt with by adjusting the flow rate of rolling oil.
The control itself is extremely simple and highly effective. In the above embodiment, the color tone state, that is, when detecting an abnormality in the rolling oil lubrication state, the upper and lower limit values α and β of the torque value deviation τα were set to 0.1 and −0.1, respectively, The present invention is not limited to this, and the upper and lower limit values α and β may be appropriately changed based on an allowable color tone difference.

【The invention's effect】

As described above, according to the present invention, it is possible to easily detect an abnormality in the color tone state without installing a special color tone sensor or its analyzing device around the rolling mill, and to detect a color tone difference between the front and back surfaces of the rolled material or the front and back surfaces. It is possible to obtain an excellent effect that it is possible to prevent the occurrence of a color tone difference in each longitudinal direction.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a front and back surface color tone control apparatus for rolled material according to the present invention, and FIG. 2 is a mill speed command and rolls for upper and lower work rolls for explaining the principle of the present invention. FIG. 3 is a diagram showing the relationship with the current value of the drive motor, and FIG. 3 is a ratio of defective products due to current value deviation and color difference of the original drive motor of the upper and lower work rolls, similarly for explaining the principle of the present invention. FIG. 4 is a side view including a partial block diagram and a pipeline diagram showing the equipment configuration of a cold tandem mill line which is an object of the present invention, and FIG. FIG. 6 is a flow chart showing the control means of the mill master control device in the equipment, and FIG. 6 is a front view showing the torque transmission mechanism near the motor. 10 …… Cold tandem mill line, 12 …… Steel strip, 14 …… Pay-off reel, 16 …… Stand, 18 …… Tandem mill, 20 …… Tension reel, 22 …… Rolling oil supply device, 24 …… Mill Main controller, 26A, 26B …… work roll, 28 …… motor, 30 …… speed controller, 51 …… mechanical tight gear.

Claims (1)

(57) [Claims] 1. A front and back surface of a rolled material when biting rolling is performed while lubricating the rolled material by a mechanical-tight rolling machine in which a pair of work rolls arranged opposite to each other are driven by a single motor. In the color tone control device, a torque detection unit that detects the torque of each spindle of the pair of work rolls, a unit that calculates the torque value deviation by dividing the difference between the detected torques by the average value of the detected torques, and the calculation. Flow rate control means for changing the flow rate of the rolling oil supplied to the work rolls when the torque value deviation deviates from the predetermined upper and lower limit values, and front and back surface color tone control of the rolled material characterized by comprising: apparatus.