RU2320435C2 - Continuous rolling mill kinematic parameters monitoring method - Google Patents

Abstract

FIELD: rolled stock production, namely monitoring of kinematic parameters at rolling in mill equipped with roller guides, possibly in bar and rod rolling mills, mainly equipped with finish rolling units of stands.

SUBSTANCE: method comprises steps of measuring angular velocity of roller rotation of roller guide of near- roll fitting by means of magnetic field pickups. According to known diameter values of rollers linear motion speed of strip is calculated. Then calculated values of linear speed are compared with reference values corresponding to speed mode characterized by minimum tension values between stands of mill.

EFFECT: improved accuracy of monitoring process.

Description

The invention relates to rolling production, and in particular to the control of kinematic parameters during rolling on mills equipped with roller wiring, and can be used on high-quality and wire mills, mainly equipped with finishing blocks of stands.

Known, for example, is a method of measuring speed during rolling on continuous mills, namely measuring the speed of a strip using a device called a spinner (Chekmarev A.P., Pobegailo G.G. Precise rolling of high-quality profiles. M .: "Metallurgy" , 1968, p.209-210). The method consists in measuring the linear velocity of the grooved roller pressed against a moving strip using a contact disk connected to the roller and in contact with the electric pickup. The corrugated roller is pressed against the rolled strip and transmits rotation to the contact disk. The speed of the rolled strip is determined by the number of marks obtained by each revolution of the contact disk for a certain period of time.

The disadvantage of this measurement method is that slippage of the contact roller and significant vibrations of the moving strip make it difficult to measure rolling speeds in excess of 15 m / s due to disturbance of contact with the roller.

Closest to the invention, the technical solution in essence is a method for controlling the rotation of the rollers of the roller wiring of the rolling reinforcement of the finishing blocks of the stands of the rolling mill, implemented using roller wiring (Patent of the Russian Federation No. 2013151, class B21B 39/16, 1994) equipped with rotation sensors.

The essence of the method of controlling the rotation of the rollers of the roller wiring of the rolling reinforcement is as follows. Roller wiring is installed directly near the deformation zone, mainly at the entrance and / or exit of the strip from the deformation zone. Two electrical sensors for rotating the rollers, one for each roller, are installed on the roller wiring in the immediate vicinity of the rollers. Before installing rotation sensors, a magnetic mark is applied to the end surface of the rollers. The scattering field of the magnetized region of the roller changes the characteristic of the sensor, creating a signal proportional to the induced EMF in the sensor coil, which is removed and transmitted to the roller rotation control system, it is processed, converted and compared with a predetermined value that corresponds to the presence of roller rotation during normal rolling mode.

The advantages of this method of controlling the rotation of the rollers over the analogue is that the method is implemented in the immediate vicinity of the deformation zone, where the vibration of the strip is minimal, the presence of a pair of rollers holding the strip in a certain position eliminates slippage of the rollers. The slipping or stopping of the rollers can take place only when the bearings wear and rupture and the rollers get jammed when scale gets into the rolling reinforcement, which indicates the inoperability of the roller wiring.

The disadvantages of this method include the inability to ensure the specified accuracy of the transverse dimensions of the rental along the length of the strip, due to the inability to determine the linear speed of the rollers and, therefore, the inability to control the tension. This is because the signal actually received in the coil of the electric sensor is incommensurable not only with the electromagnetic background of the rolling mill, but also with the scattering magnetic field outside the magnetic mark, which leads to the presence of a region of remanent magnetization along the entire perimeter of the roller and, as a result, attenuation of the signal itself. After removing and transmitting such a signal to the control system, during its subsequent processing and conversion, it is possible to evaluate only the presence of rotation of the rollers of the roller wires of the rolling reinforcement, since the received signal is not sufficiently reliable in the signal-to-noise ratio.

Thus, the method of controlling the rotation of the rollers used in the prototype is a method of automatically monitoring the operability of roller wiring (rotation of the rollers) when it is impossible to visually control it in the line of finishing blocks of the mill stands, closed by a protective casing, due to the high rolling speeds.

The basis of the invention is the task of creating a method for controlling the kinematic parameters of a rolling mill, which will improve the accuracy of the transverse dimensions of the rental along the length of the strip.

The problem is achieved in that in the method of controlling the kinematic parameters of the rolling mill, the angular velocity of the rollers of the roller wiring of the rolling reinforcement is measured by magnetic field sensors. The known diameters of the rollers calculate the linear speed of the strip. Next, they compare the obtained values of the linear speed of the rollers with the reference values that correspond to the speed mode with minimal tension between the stands of the mill.

The main condition for rolling in a continuous mill is the constancy of second volumes, presented in the agreed rolling mode by the expression C = F _i V _i , where F _i is the cross-sectional area of the roll at the exit from the i-th stand, V _i is the speed of the strip leaving i th stand, C - constant rolling. The consequence of this condition is the formula for determining the coefficient of drawing in the i-th stand:

In a mismatched mode, the rolling constant in each stand changes due to a change in the cross-sectional area or a change in the strip exit speed when backwater or tension occurs. Given these changes, the new speed V _i 'and the area F _i ' are expressed as follows:

where ΔV _i and ΔF _i are, respectively, changes in the speed and cross-sectional area of the peal at the exit from the i-th stand.

The new rolling constant is expressed as the product of the new speed and area

,

,

and the new values of the extraction coefficients

Thus, by the ratio of the values of the reference μ _i and the measured μ _i 'hoods, one can judge the inconsistency of the high-speed rolling mode. In both group and individual drives, the main parameters for comparison are the linear velocity ratios V _i / V _i-1 for adjacent stands of the inter-stand space. Monitoring and maintaining a constant ratio of linear speeds provides a more accurate adjustment of the rolling mill.

Compared with the closest analogue, the proposed method for controlling the kinematic parameters of the rolling mill has the following significant distinguishing features:

- measure the angular speed of rotation of the rollers of the roller wiring of the rolling reinforcement with magnetic field sensors;

- recalculate angular velocities into linear ones and determine their relationships for adjacent stands (stand groups);

- compare the obtained values of the ratios with the reference and evaluate the correct settings of the rolling mill.

The proposed method controls the kinematic parameters during rolling on a continuous mill by comparing the measured values with the set. The control of kinematic parameters includes controlling the ratio of linear speeds, ensuring minimal tension in the inter-stand spaces of the continuous mill, and hence the specified accuracy of the transverse dimensions of the rolled products along the length of the rolled strip.

Replacing electrical rotation sensors with magnetic field sensors makes it possible to obtain an electrical signal that is independent of the rate of change of the magnetic flux, but is determined by the magnitude of the scattering field from the magnetized areas of the roller wiring rollers. This allows the use of such sensors for any real rotation speeds.

The implementation of the proposed method is as follows.

The reference values of the ratios V _{i + 1} / V _{i are} calculated by measuring the angular and calculating the linear rolling speeds when the mill is set to high-speed mode, which ensures the geometric dimensions of the roll along the entire length of the strip in a given tolerance range with a minimum tension between the stands. The obtained reference values are stored in the memory of a personal computer.

At the entrance to the rolling stand, falling into the roller wiring, the strip interacts with the rollers of the roller wiring, bringing the rollers into rotation. Magnetic field sensors convert the modulation of the magnetic field generated on the surface of the roller into an electrical signal, which is normalized by the driver and transmitted to the controller. The controller calculates the angular speeds of rotation of the rollers and transfers information to a personal computer. Taking into account the geometrical dimensions of the roller, the angular velocity of the rotation of the roller is converted to linear. The personal computer visualizes the parameters of the speed modes of rotation of the rollers in digital form and / or in the form of diagrams.

The difference between the reference and calculated ratios of linear speeds determines the presence of tension or backwater, relative to a given speed mode of rolling. When backwater, the value of speed V _i should be increased, with excessive tension - reduced. For continuous mills with an individual drive, the speed can be increased (decreased) by increasing (decreasing) the revolutions of the drive motor and / or increasing (decreasing) the roll gap. When rolling in stands with a group drive, changes in the linear rolling speed in a specific stand are achieved only by changing the gap.

Consider the application of the method of controlling kinematic parameters by the example of rolling a wire rod with a diameter of 5.5 in a high-speed block of a wire mill 150 with a group drive.

Table 1 shows the reference rolling mode, in table 2 - the mismatched rolling mode in the block. The following notation is accepted:

ω is the frequency of rotation of the roller wiring;

V is the linear speed of the strip;

μ is the ratio of the linear speeds of the strip in adjacent stands (drawing coefficient);

Δμ / μ is the relative change in the coefficient of drawing.

In accordance with the proposed method, we measured the frequency of rotation of the rollers, the rolling speed, and determined the ratio of c for each of the three stands of the finishing block of the continuous mill with normal tuning of the mill.

As you can see, the ratio of speeds differ from the reference values, which led to a mismatch in the speed mode of rolling. Increased tension negatively affects the accuracy of the wire rod profile.

Table 1
The parameters of the reference rolling mode of wire rod ⌀ 5.5 mm Roll clearance ω, 1 / s V, m / s μ 1.7 89.1 14.6 1,212 2.2 116.3 19.0 1,301 1,5 142.5 23.3 1,226 H = 5.57 V = 5.51

table 2
Mismatched rolling parameters ан 5.5 mm Roll clearance ω ', 1 / s V ', m / s μ ' Δμ / μ,% 1.8 88.5 14.45 1,164 -3.9% 2.2 109.6 17.90 1,239 -4.9% 1.8 128.2 20.94 1,170 -3.9% H = 5.57 V = 5.31

So, with an uncoordinated rolling mode, a wire rod was obtained in the middle part of the riot with a horizontal dimension B differing by 0.2 mm.

The proposed method for controlling the kinematic parameters of the rolling mill allows to comprehensively solve the problems of stabilization of the process, to eliminate or minimize the mill stops associated with the violation of the process, to significantly reduce the drawdown of the roll width, thereby increasing the accuracy of the size of the wire rod along the length of the riot.

Claims (1)

A method for controlling the kinematic parameters of a rolling mill, including controlling the rotation of the rollers of the rolling reinforcement using sensors installed on the rolling reinforcement, characterized in that the kinematic parameters of the rolling mill are controlled by measuring the angular velocity of rotation of the rollers with magnetic field sensors, followed by determining linear velocities and ratios of linear rolling speeds in adjacent stands or groups of stands and comparing the obtained speed ratios with the reference values.