CN100551567C - Control Method of Rolling Load Balance in Double-motor Driven Cold Strip Mill - Google Patents

Abstract

The invention discloses a double-motor driven control method for load balance of a working roll of a strip steel cold rolling mill, which is characterized by comprising the following steps of: the method is realized by determining the technological parameters of the roller and the emulsion, and dynamically adjusting the unit tension and the reduction rate of rolling and the acceleration of a transmission motor during the speed rising. The invention creates a friction state suitable for different rolling loads in upper and lower working roll deformation zones by determining reasonable roll roughness, roll service cycle, suitable emulsion process parameters, emulsion flow control and other means. And dynamically adjusting control parameters such as the reduction rate, the unit tension, the acceleration of a transmission motor and the like of the cold continuous rolling unit according to the actual amount of the strip steel rolled by the working rolls to compensate the abrasion of the working rolls caused by overlong service cycle. The comprehensive control method can obviously improve the stability of the rolling process and control the speed difference of the motor caused by the rolling load difference of the upper working roll and the lower working roll within 3 percent.

Description

Control Method of Rolling Load Balance in Double-motor Driven Cold Strip Mill

technical field

The invention belongs to the field of steel rolling, and is suitable for the production process control of a cold-rolled strip mill driven by double motors, in particular to a control method for rolling load balance of a cold-rolled strip mill driven by double motors.

technical background

In the cold rolling production process of strip steel, due to the difference in the rolling process parameters of the upper and lower rolls, the rolling state in the rolling deformation zone of the upper and lower rolls will be different. Due to the different rolling states of the upper and lower work rolls, there are differences in rolling loads such as rolling forces and rolling moments of the upper and lower work rolls.

For the cold rolling mill control system driven by dual motors, the load balance control function of the two motors for the upper and lower rolls is provided. The purpose of this motor load balance control is to ensure that the current and motor torque of the upper and lower roller drive motors are consistent in the rolling process, otherwise the rolling process will not be able to proceed.

The control system of each transmission motor is equipped with a load control inner loop and a speed control outer loop, so the speed of a single working motor can be precisely controlled. However, in order to satisfy the load difference of the double-drive motors during rolling is controlled within a certain range, the load balance control of the motors meets the requirement that the loads of the drive motors of the upper and lower rolls are consistent by adjusting the speed of the motors.

In this way, if there is a large difference in the rolling load of the upper and lower rolls during the rolling process, this will cause a large difference in the load of the upper and lower roll drive motors, and the adjustment of the load balance control system of the motor will make the speed difference of the upper and lower roll motors obviously increase. The increase of the speed difference of the upper and lower roll motors increases the speed difference of the upper and lower work rolls. When the speed difference of the upper and lower work rolls increases to a certain value, the surface of the strip will have slip marks, and the strip will be rubbed by the upper and lower rolls. The strip breaks due to rolling action and causes production accidents.

Due to the above-mentioned problems in the cold rolling mills driven by dual motors, the newly built cold rolling mills generally adopt the single motor drive mode in recent years. However, the cold rolling mill driven by dual motors is still widely used in actual production, so it is necessary to take appropriate methods to overcome the above-mentioned shortcomings of the dual-motor drive system.

Contents of the invention

Aiming at the problems existing in the existing dual-motor drive cold rolling mill production technology, the present invention proposes a comprehensive control method, that is, a control method for the rolling load balance of the dual-motor drive cold-rolling strip mill, which can control the up and down during the rolling process. The speed difference of the work rolls is controlled within a small range, so as to ensure the stability of the rolling process, avoid surface defects of the strip, and not affect the normal production process of the rolling mill.

The technical solution of the present invention is as follows, which is realized by determining the technological parameters of the roll and the technological parameter values of the emulsion, and dynamically adjusting the rolling unit tension, the reduction rate, and the acceleration when the transmission motor speeds up.

Each parameter of the present invention is as follows:

The roll process parameters include the work roll roughness, the roll maximum rolling cycle and the roll process parameter values of the work roll matching roll diameter difference,

in,

Work roll surface roughness: 0.9μm～1.1μm,

Maximum rolling cycle: 4200 tons,

Maximum roller difference: 4mm.

Emulsion process parameters are:

Flow rate>5000l/min,

Concentration: 3.0～3.5%,

PH value: 5~8,

Conductivity<120μs/cm,

Saponification value>120mg KOH/g,

E.S.I: 40~60%, E.S.I represents the physical quantity of the stability of the emulsion,

Temperature: 55～60℃,

Pressure: 8～10Bar,

Emulsion flow ratio of upper and lower work rolls: 0.8~0.85.

The unit tension control value at the exit of the rolling mill is,

When the work roll rolling cycle is 0-2000 tons, the unit tension value is 1.0σMpa;

When the work roll rolling cycle is 2000-3000 tons, the unit tension value is 1.15σMpa;

When the work roll rolling cycle is 3000-4200 tons, the unit tension value is 1.4σMpa.

Where σ is the unit tension at the exit of the rolling mill.

The unit tension control value at the exit of the rolling mill,

When the work roll rolling cycle is 0-2000 tons, the reduction rate value is 1.0r%,

When the work roll rolling cycle is 2000-3000 tons, the reduction rate value is 0.9r%,

When the work roll rolling cycle is 3000-4200 tons, the reduction rate value is 0.7r%,

where r is the reduction rate.

Motor speed up acceleration control,

When the work roll rolling cycle is 0-2500 tons, the acceleration value is 1.0m/s ² ,

When the working roll rolling cycle is 2500-4200 tons, the acceleration value is 0.6m/s ² .

In the present invention, two or more of the above parameters can be used or used simultaneously to control the rolling load balance of the double-motor driven cold strip mill.

The present invention adopts the method of combining computer automatic control and measurement technology, friction and lubrication state control, and cold continuous rolling strip steel dynamic rolling procedure technology to control the rolling process of the upper and lower work rolls and the strip steel contact deformation zone during the cold rolling strip steel rolling process. The rolling load is comprehensively controlled to balance the rolling force and rolling moment in the upper and lower deformation zones, and reduce the rolling load difference, thereby reducing the speed difference between the upper and lower work rolls caused by the load difference of the drive motors of the upper and lower rolls. Through the above comprehensive control method, the stability of the rolling process can be obviously improved, and the motor speed difference caused by the rolling load difference of the upper and lower work rolls can be controlled within 3%.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 is a schematic diagram of a dual-motor drive rolling mill.

Fig. 2 is the measured data of transmission motor speed in the rolling process under the process condition of embodiment 1,

Fig. 3 is the measured data of transmission motor speed in the rolling process under the embodiment 2 technological conditions,

Fig. 4 is the actual measurement data of the transmission motor speed during the rolling process under the process conditions of embodiment 3.

Detailed ways

As shown in Figure 1, 2 and 3 are upper and lower work rolls, 1 and 4 are upper and lower support rolls, 5 are steel plates, and 6 and 7 are drive motors for upper and lower rolls.

The invention determines the working range of the surface roughness of the original work roll through a large number of industrial experiments: 0.9-1.1 μm; the maximum rolling cycle of the work roll is 4200 tons; the maximum diameter difference between the upper and lower work rolls is 4mm. When matching work rolls, if the diameter difference between the upper and lower work rolls is greater than 1 mm, the large diameter work roll is used for the upper roll, and if the diameter difference is less than 1 mm, the roll with high surface roughness is used for the upper roll. Determine the emulsion process parameters (table 1) by a large number of industrial experiments:

Table 1 Emulsion Process Parameters

During the rolling process, by controlling the opening degree of the valve in the emulsion injection system equipment, the ratio of the emulsion injection flow rate of the upper work roll to the emulsion injection flow rate of the lower work roll is 0.8-0.85.

When the total amount of strip rolled by the work rolls changes, the unit tension at the exit of the rolling mill (Table 2), the reduction rate (Table 3) and the acceleration of the upper and lower roll drive motors are dynamically adjusted according to the total amount of rolled steel of the work rolls (Table 4).

Table 2 Unit Tension Control Value of Rolling Mill Export

Table 3 Mill reduction control value

Table 4 Motor speed-up acceleration control value

In Table 2 and Table 3, the unit tension σ and reduction rate r at the exit of the rolling mill are not fixed values, they are calculated by the computer model system of the control system according to the steel type and specification of the rolled strip.

The invention proposes to dynamically correct the unit tension, the reduction rate and the motor speed-up acceleration according to the roll rolling cycle on the basis of the calculated value of the control system.

Example 1:

The original initial roughness of the upper and lower work rolls are 0.91μm and 0.95μm respectively. The total amount of strip rolled by the work rolls during strip rolling is 1524 tons. The strip rolled steel is st12, the entrance thickness is 2.19mm, the reduction rate r is 20%, and the strip width is 1250mm. During the rolling process, the unit tension σ at the exit of the rolling mill is 120Mpa, and the acceleration of the motor during the acceleration process is 1m/s ² .

The concentration of the emulsion is 3.25%, the temperature is 57°C, the pH value is 6.1, the conductivity is 101μs/cm, the saponification value is 170mg KOH/g, the E.S.I is 51%, the injection pressure is 9.1Bar, and the work roll emulsion injection flow rate is 5140l/min .

Under the conditions of the above process parameters, the actual values of the torque and speed of the upper and lower roll drive motors during the strip rolling process are shown in Figure 2.

Example 2:

The original initial roughness of the upper and lower work rolls are respectively: 0.98μm and 0.94μm. The total amount of strip steel rolled by the work rolls during strip rolling is 2422 tons. The strip rolled steel is spcc, the entrance thickness is 2.17mm, and the strip width is 1220mm. The initial reduction rate r set by the computer is 18%, and the revised reduction rate is 0.9×18%. The unit tension σ at the exit of the rolling mill initially set by the computer is 125Mpa, and the unit tension at the exit after correction is 1.15×125Mpa. The acceleration of the motor is initially set at 1m/s ² , and the acceleration after correction is 0.8m/s ² .

The concentration of the emulsion is 3.5%, the temperature is 58°C, the pH value is 6.4, the conductivity is 106μs/cm, the saponification value is 173mg KOH/g, the E.S.I is 55%, the injection pressure is 9.7Bar, and the injection flow rate of the work roll emulsion is 5410l/min .

Under the conditions of the above process parameters, the actual values of the torque and speed of the upper and lower roll drive motors during the strip rolling process are shown in Figure 3.

Example 3:

The original initial roughness of the upper and lower work rolls: 1.04μm, 1.14μm. The total amount of strip rolled by the work rolls during strip rolling is 3104 tons. The strip rolled steel is st12, the entrance thickness is 1.15mm, and the strip width is 1225mm. The initial reduction rate r set by the computer is 33%, and the revised reduction rate is 0.7×33%. The unit tension σ at the exit of the rolling mill initially set by the computer is 125Mpa, and the unit tension at the exit after correction is 1.4×125Mpa. The acceleration of the motor is initially set at 1m/s ² , and the acceleration after correction is 0.6m/s ² .

The concentration of the emulsion is 3.5%, the temperature is 59°C, the PH value is 7.2, the electrical conductivity is 103μs/cm, the saponification value is 170mg KOH/g, the E.S.I is 51%, the injection pressure is 9.3Bar, and the work roll emulsion injection flow rate is 5141l/min .

Under the conditions of the above process parameters, the actual values of the torque and speed of the upper and lower roll drive motors during the strip rolling process are shown in Figure 4.

Through the rolling process such as embodiment 1～embodiment 3, the actual data of upper and lower roll transmission motor speed can be found, adopt roll process parameter of the present invention, emulsion process parameter and corresponding dynamic rolling regulation, the rolling of strip steel The process is stable, and the speed difference of the motors of the upper and lower rollers is controlled within 3%.

Claims (6)

1. A method for controlling the work roll load balance of a double-motor-driven strip steel cold rolling mill, characterized in that: by determining the process parameters of the rolls and the value of the process parameters of the emulsion, dynamically adjusting the rolling unit tension, the reduction rate and the drive motor Acceleration during acceleration is achieved. 2. A method for controlling load balance of work rolls in a dual-motor driven cold strip mill according to claim 1, wherein the process parameters of the rolls include the roughness of the work rolls, the maximum rolling cycle of the rolls, and the The roll process parameter value of the roll diameter difference, in, Work roll surface roughness: 0.9μm～1.1μm, Maximum rolling cycle: 4200T, Maximum roller difference: 4mm. 3. The method for controlling the work roll load balance of a double-motor-driven cold strip mill according to claim 1, wherein the process parameters of the emulsion are: Flow rate>5000l/min, Concentration: 3.0～3.5%, PH value: 5~8, Conductivity<120μs/cm, Saponification value>120mg KOH/g, E.S.I: 40~60%, E.S.I represents the physical quantity of the stability of the emulsion, Temperature: 55～60℃, Pressure: 8～10Bar, Emulsion flow ratio of upper and lower work rolls: 0.8~0.85. 4. A method for controlling load balance of work rolls in a dual-motor driven cold strip mill according to claim 1, wherein the unit tension control value at the exit of the rolling mill is, When the work roll rolling cycle is 0-2000 tons, the unit tension value is 1.0σMpa; When the work roll rolling cycle is 2000-3000 tons, the unit tension value is 1.15σMpa; When the work roll rolling cycle is 3000-4200 tons, the unit tension value is 1.4σMpa, where σ initially sets the unit tension. 5. The method for controlling the work roll load balance of a double-motor driven cold strip mill according to claim 1, characterized in that: When the work roll rolling cycle is 0-2000 tons, the reduction rate value is 1.0r%, When the work roll rolling cycle is 2000-3000 tons, the reduction rate value is 0.9r%, When the work roll rolling cycle is 3000-4200 tons, the reduction rate value is 0.7r%, Where r is the initial set rolling reduction ratio. 6. The method for controlling the load balance of work rolls in a double-motor driven strip cold rolling mill according to claim 1, characterized in that the acceleration of the motor is controlled, When the work roll rolling cycle is 0-2500 tons, the acceleration value is 1.0m/s ² , When the working roll rolling cycle is 2500-4200 tons, the acceleration value is 0.6m/s ² .

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