CN115488156A - Method and system for vibration detection and protection of hydraulic pressing position control system of cold rolling mill - Google Patents

Abstract

The invention provides a vibration detection and protection method and system of a hydraulic press position control system of a cold rolling mill. First, the position deviation depth filter is performed to obtain the position deviation filter value; the difference between the actual position deviation value and the position deviation filter value is calculated. Get the vibration detection variable V; set the amplitude judgment value A, the amplitude judgment time window W, the vibration judgment number N, and the non-vibration judgment duration T; judge the magnitude of the shock detection variable V and the amplitude judgment value A, when V>A , the positive vibration flag F is set, when V<-A, the positive vibration flag F is reset; the positive vibration flag F pulse is generated; the oscillation judgment step: count the number of positive vibration flag F pulses within the W time window, and judge when it exceeds N Oscillation, when the sign of positive oscillation lasts T, or the sign of negative oscillation lasts T, it is judged not to oscillate. By adopting the invention, the vibration of the position control system can be effectively suppressed, unmanned maintenance can be realized, the speed of the unit can be greatly increased, and the position vibration of the oil cylinder caused by mechanical resonance can be avoided.

Description

Method and system for vibration detection and protection of hydraulic pressing position control system of cold rolling mill

technical field

The invention relates to the field of cold rolling control, in particular to a vibration detection and protection method and system for a hydraulic pressing position control system of a cold rolling mill.

Background technique

The cold rolling mill is used for rolling hot-rolled strip steel at room temperature. Figure 1 is a schematic structural diagram of the cold rolling mill. Rolling between the upper and lower work rolls, pressing the oil cylinder to drive the upper roll system (including the upper backup roll, upper intermediate roll and upper work roll) to generate rolling force for strip rolling, the position of the piston rod of the pressing oil cylinder (hereinafter referred to as pressing Down position) is the core link of the depressing control system. The depressing position is measured by a high-precision position sensor (the measurement accuracy is below 0.5um). When the hydraulic piston rod is at the upper limit position, the hydraulic position is zero. When the piston rod is pressed down, the hydraulic position gradually increases. Under the action of automatic thickness control in the rolling process, the actual position of the press changes drastically following the given position, which requires that the hydraulic press position control system must have a high response sensitivity. , since the core control link of the hydraulic control system is the proportional control, the proportional control gain becomes a key control parameter of the hydraulic control system. During the rolling process, the transmission system drives the work rolls to rotate at a given speed, and the rolling speed of the work rolls can be intervened according to the actual situation of the hydraulic position control system.

Figure 2 is a typical hydraulic pressure position control system. The position deviation generates voltage adjustment through the proportional link, and the amplification link converts the voltage adjustment into the current adjustment of the servo valve, and the servo valve generates the hydraulic flow adjustment under the action of the current adjustment. , the hydraulic flow adjustment amount drives the hydraulic cylinder to change the position of the oil cylinder. The actual position of the oil cylinder reflects the position change of the piston rod based on the unloading position. The AGC control value plus the position setting of the manual oil cylinder forms the total oil cylinder given position. The closed-loop control system tries to make the actual position of the oil cylinder follow the change of the given position of the oil cylinder. The difference between the actual position of the oil cylinder and the given position of the oil cylinder forms the position deviation of the oil cylinder. In fact, due to various reasons, the position deviation of the oil cylinder fluctuates, which seriously affects the smooth progress of production. When the actual position of the oil cylinder oscillates, a natural approach is to manually reduce the control gain appropriately, but the adverse effect of this approach is the increase of the control static error, which increases the maintenance cost and is not conducive to the AGC control accuracy improvement. The invention proposes an automatic detection method for the actual position vibration of the oil cylinder, and when the vibration is detected, the gain is automatically reduced, and the gain is automatically restored after the vibration is eliminated. If the vibration of the oil cylinder position is caused by mechanical resonance, the vibration is detected again after 3 seconds When the rolling speed is appropriately reduced until the shock disappears.

Contents of the invention

Aiming at the defects in the prior art, the object of the present invention is to provide a method and system for detecting and protecting oscillation of the hydraulic pressing position control system of a cold rolling mill.

A vibration detection and protection method for a hydraulic press position control system of a cold rolling mill according to the present invention includes the following steps:

Position deviation depth filtering step: performing position deviation depth filtering to obtain a position deviation filtering value;

Difference calculation step: calculate the difference between the actual position deviation value and the position deviation filter value to obtain the vibration detection variable V;

Parameter setting steps: set the amplitude judgment value A, the amplitude judgment time window W, the vibration judgment number N, and the non-vibration judgment duration T;

Judging step: judging the size of the oscillation detection variable V and the amplitude judgment value A, when V>A, the positive vibration flag F is set, and when V<-A, the positive vibration flag F is reset;

Pulse generating step: generating positive vibration flag F pulse;

Oscillation judging steps: Count the number of positive vibration flag F pulses within the W time window. When it exceeds N, it is judged to be a shock. When the positive vibration flag lasts for T, or the negative vibration flag lasts for T, it is judged not to oscillate.

Preferably, a gain intervention step is also included: when an oscillation is detected, active intervention is performed on the control gain, and the gain is reduced to a set value of a preset ratio within a set time; when no oscillation is detected, within a set time Return the gain to the set value.

Preferably, the set time is 1500ms, and the preset ratio is 30%.

Preferably, a shock detection step is also included: after the shock is detected for the first time after accelerating to the set speed, the shock flag is set, and when the shock flag is detected again after the shock flag is delayed for 3s, the speed-down flag is generated and the shock flag is reset at the same time .

Preferably, when the deceleration flag is generated, the difference between the speed of the computer unit and 50mpm is locked to obtain the deceleration target value.

Preferably, when the speed of the unit drops to the deceleration target value, the deceleration ends, the deceleration flag is reset, and the hold command resets the deceleration flag directly.

Preferably, the amplitude judgment value is calculated from the rolling speed by the FG function.

According to the present invention, a shock detection and protection system of the hydraulic pressing position control system of a cold rolling mill includes the following modules:

Position deviation depth filtering module: perform position deviation depth filtering to obtain position deviation filtering value;

Difference calculation module: calculate the difference between the actual position deviation value and the position deviation filter value to obtain the vibration detection variable V;

Parameter setting module: set the amplitude judgment value A, the amplitude judgment time window W, the vibration judgment number N, and the non-vibration judgment duration T;

Judgment module: judge the size of the vibration detection variable V and the amplitude judgment value A, when V>A, the positive vibration flag F is set, and when V<-A, the positive vibration flag F is reset;

Pulse generation module: generate positive vibration flag F pulse;

Oscillation Judgment Module: Count the number of positive vibration flag F pulses in the W time window. When it exceeds N, it is judged to be a shock. When the positive vibration flag lasts for T, or the negative vibration flag lasts for T, it is judged not to shake.

Preferably, a gain intervention module is also included: when an oscillation is detected, active intervention is performed on the control gain, and the gain is reduced to a set value of a preset ratio within a set time; when no oscillation is detected, within a set time Return the gain to the set value.

Preferably, a shock detection module is also included: after the shock is detected for the first time after accelerating to the set speed, the shock flag is set, and when the shock flag is detected again after a delay of 3s, the speed-down flag is generated and the shock flag is reset at the same time .

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention effectively suppresses the oscillation of the position control system, realizes unmanned maintenance, and greatly increases the speed of the unit.

2. The present invention avoids vibration of the cylinder position caused by mechanical resonance through vibration discrimination and protection.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Figure 1 is a schematic diagram of the structure of a cold rolling mill.

Fig. 2 is a schematic diagram of the hydraulic pressure position control system.

Fig. 3 is a schematic diagram of the actual position oscillation of the oil cylinder.

Fig. 4 is a flowchart of oscillation detection and non-oscillation detection.

Fig. 5 is a schematic diagram of typical parameter setting of the amplitude judgment value of the FG function.

Figure 6 is the actual effect diagram of vibration detection and protection.

Fig. 7 is a schematic diagram of the vibration of the oil cylinder position caused by mechanical resonance.

Fig. 8 is a flow chart of detection of mechanical resonance and oil cylinder position oscillation.

Fig. 9 is a curve diagram of mechanical resonance and oil cylinder position oscillation detection and protection effect.

detailed description

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

As shown in Figures 1 to 9, the present invention proposes a vibration detection and protection method and system for the hydraulic press position control system of a cold rolling mill. When the vibration is detected, the gain is automatically reduced, and the gain is automatically restored after the vibration is eliminated. If the vibration of the oil cylinder position is caused by mechanical resonance, when the vibration is detected again after 3 seconds, the rolling speed will be appropriately reduced until the vibration disappears.

Specific description: Figure 4 is a flowchart of oscillation detection and non-oscillation detection. When performing vibration detection, firstly, depth filtering of the position deviation is performed to obtain the filtered value of the position deviation, the difference between the actual position deviation and its filtered value is calculated to obtain the vibration detection variable V, and the amplitude judgment value A[um] is set. Set the amplitude judgment time window W[ms], set the vibration judgment number N, and set the non-vibration judgment duration T[s]. When V>A, the positive vibration flag F is set, when V<-A, the positive vibration flag F is reset, and the positive vibration flag F pulse is generated, and the number of positive vibration flag F pulses is counted in the W time window. Judging the oscillation, when the positive oscillation sign lasts for T, or the negative oscillation sign lasts for T, it is judged not to be in oscillation.

The amplitude judgment value is related to the rolling speed. The greater the rolling speed, the greater the amplitude judgment value. The amplitude judgment value is calculated from the rolling speed through the FG function. Figure 5 is the typical parameter setting of the amplitude judgment value of the FG function, and X represents rolling Speed [0.1mpm], Y indicates the amplitude judgment value [um].

When the oscillation is detected, the control gain must be actively intervened, and the gain is reduced to 30% of the set value within 1500ms. When no oscillation is detected, the gain is restored to the set value within 1500ms. Figure 6 is the actual effect curve of shock detection and protection. When the shock is detected, the gain will automatically decrease. When the shock is not detected, the gain will automatically recover. After the shock occurs, it will be eliminated after a short period of shock, which has the effect of shock protection.

As the rolling speed increases, mechanical resonance may occur, see Figure 7. It can be seen from Figure 7 that when the rolling speed reaches 1160mpm, mechanical resonance occurs, causing the position of the oil cylinder to oscillate. At this time, the position of the oil cylinder cannot be eliminated by reducing the gain. It can only be eliminated by appropriately reducing the unit speed, but it cannot be simply This is because it will reduce the production line capacity. In fact, during the acceleration process, when the speed of the unit reaches 1160mpm, mechanical resonance occurs, causing the vibration of the oil cylinder position. After that, the acceleration continues, and the mechanical resonance and the vibration of the oil cylinder position disappear immediately, but when When the unit speed stays at about 1160mpm, it will continue to trigger mechanical resonance and oil cylinder position oscillation. Once such a serious situation is detected, the rolling speed must be appropriately reduced.

Figure 8 shows the flow chart of mechanical resonance and oil cylinder position vibration detection. After the vibration is detected for the first time after accelerating to 1000mpm, the vibration flag is set. If the vibration flag is delayed for 3s, if the vibration is detected again, a deceleration flag is generated, and at the same time Reset the oscillating flag. When the deceleration sign is generated, the difference between the computer group speed and 50mpm is locked to obtain the deceleration target value. When the unit speed drops to the deceleration target value, the deceleration ends and the deceleration flag is reset. The hold command can directly reset the deceleration flag.

Figure 9 shows the mechanical resonance and oil cylinder position oscillation detection and protection effect curves. When the oscillation is detected again after 3 seconds, it will cause the first speed reduction. When the oscillation is detected again after 3 seconds, it will cause the second speed reduction. After the first deceleration, the mechanical resonance and the vibration of the oil cylinder position disappeared.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", The orientation or positional relationship indicated by "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, rather than indicating or implying the referred device Or elements must have a certain orientation, be constructed and operate in a certain orientation, and thus should not be construed as limiting the application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (10)

1. A vibration detection and protection method for a hydraulic pressing position control system of a cold rolling mill is characterized by comprising the following steps:

and a position deviation depth filtering step: carrying out position deviation depth filtering to obtain a position deviation filtering value;

and a difference value calculation step: calculating a difference value between the actual position deviation value and the position deviation filtering value to obtain a vibration detection variable V;

a parameter setting step: setting an amplitude judgment value A, an amplitude judgment time window W, an oscillation judgment number N and a non-oscillation judgment duration T;

a judging step: judging the magnitudes of the oscillation detection variable V and the amplitude judgment value A, setting a positive oscillation flag F when V is greater than A, and resetting the positive oscillation flag F when V < -A;

a pulse generation step: generating a positive vibration mark F pulse;

an oscillation judging step: counting the pulse number of the positive vibration mark F in the W time window, judging oscillation when the pulse number exceeds N, and judging no oscillation when the positive vibration mark lasts for T or the negative vibration mark lasts for T.

2. The shock detection and protection method of the hydraulic pressing position control system of the cold rolling mill according to claim 1, characterized by further comprising the step of gain intervention: when oscillation is detected, active intervention is carried out on the control gain, and the gain is reduced to a preset value of a preset proportion within a set time; and when no oscillation is detected, restoring the gain to the set value within the set time.

3. The oscillation detection and protection method for the hydraulic pressing position control system of the cold rolling mill according to claim 2, wherein the set time is 1500ms, and the preset proportion is 30%.

4. The shock detection and protection method of the hydraulic pressing position control system of the cold rolling mill according to claim 1, characterized by further comprising the shock detection step of: after the speed is accelerated to the set speed, setting an oscillation mark after oscillation is detected for the first time, and generating a speed reduction mark and resetting the oscillation mark when the oscillation is detected again after the oscillation mark is delayed for 3 s.

5. The oscillation detection and protection method of the hydraulic pressing position control system of the cold rolling mill according to claim 4, wherein when the deceleration mark is generated, the difference between the speed of the unit and 50mpm is calculated and locked to obtain a deceleration target value.

6. The shock detection and protection method for the hydraulic pressing position control system of the cold rolling mill according to claim 4, characterized in that when the speed of the unit is reduced to the target deceleration value, the deceleration flag is reset, and the command is kept to directly reset the deceleration flag.

7. The method for detecting and protecting the shock of the hydraulic pressing position control system of the cold rolling mill according to claim 1, wherein the amplitude judgment value is calculated from the rolling speed by an FG function.

8. The utility model provides a position control system vibrates and detects and protection system under cold rolling mill hydraulic pressure which characterized in that includes following module:

the position deviation depth filtering module: carrying out position deviation depth filtering to obtain a position deviation filtering value;

a difference value calculation module: calculating a difference value between the actual position deviation value and the position deviation filtering value to obtain a vibration detection variable V;

a parameter setting module: setting an amplitude judgment value A, an amplitude judgment time window W, an oscillation judgment number N and a non-oscillation judgment duration T;

a judgment module: judging the magnitudes of the oscillation detection variable V and the amplitude judgment value A, setting a positive oscillation flag F when V is greater than A, and resetting the positive oscillation flag F when V < -A;

a pulse generation module: generating a positive vibration mark F pulse;

a vibration judgment module: counting the pulse number of the positive vibration mark F in the W time window, judging oscillation when the pulse number exceeds N, and judging no oscillation when the positive vibration mark lasts for T or the negative vibration mark lasts for T.

9. The shock detection and protection system of the hydraulic pressing position control system of the cold rolling mill of claim 8, further comprising a gain intervention module: when oscillation is detected, active intervention is carried out on the control gain, and the gain is reduced to a preset value of a preset proportion within a set time; and when the oscillation is not detected, the gain is restored to the set value within the set time.

10. The hydraulic pressing position control system oscillation detecting and protecting system for the cold rolling mill according to claim 8, further comprising an oscillation detecting module: after the speed is accelerated to the set speed, setting an oscillation mark after oscillation is detected for the first time, and generating a speed reduction mark and resetting the oscillation mark when the oscillation is detected again after the oscillation mark is delayed for 3 s.

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