A dynamic tension control method for cold continuous rolling and frame throwing rolling

Abstract

The application relates to a dynamic tension control method for cold continuous rolling and frame throwing, wherein a mode selection module selects a 'frame throwing' mode, a process control module re-calculates the tension of four frames, the load is proportionally distributed to the frames to be worked, a basic control module adjusts the tension control strategy, when the i-th frame starts the 'frame throwing' mode, the tension setting value is set to 0, the tension control setting value of the i+1-th frame is switched to the tension control setting value of the i-th frame, the outlet tension of the i-1-th frame and the actual value of the strip thickness are switched to the inlet actual value of the i+1-th frame; under the premise of guaranteeing the thickness precision of the steel plate tension, the application throws away the fault frame to continue rolling, can avoid risks, realizes the continuity of production, realizes four-frame continuous rolling after throwing away the fault frame, saves part of the emulsion consumption and power consumption, realizes the energy-saving and consumption-reducing purposes, and makes the unit have certain flexible production capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rolling process control, in particular to a dynamic tension control method for cold continuous rolling with a frame shedding function. BACKGROUND

[0002] In the cold continuous rolling production process, it is necessary to ensure the precision of strip thickness and shape control, and also to consider the efficiency of energy consumption, which has become an inevitable topic for all cold rolling enterprises. The two are inseparable, so the demand for the frame shedding function of the cold continuous rolling mill arises at the historic moment. The 1780 pickling and rolling mill of Anshan Cold Rolling mainly includes a laser welding machine, a shallow groove turbulent pickling, a UCM five-frame continuous rolling mill, etc. In the rolling process, improving the rolling mill operation rate is the key factor for the economic and efficient operation of the cold continuous rolling mill. However, when a certain fault causes a certain frame to fail to operate normally, it will inevitably lead to the stop of the work of the five-frame rolling mill, affecting the production capacity. The so-called frame shedding function is to shed a certain frame for rolling, which changes the original five-frame continuous rolling into four-frame continuous rolling. At present, it is necessary to statistically analyze the changes in the rolling schedule such as the rolling reduction rate, tension, and bending roll, especially the tension control of the cold continuous rolling. A tension control method for frame shedding rolling is developed to solve the problem of the decline of production efficiency and capacity caused by the failure of a certain frame to operate normally in the cold continuous rolling mill. In the prior art, patent CN105921520A discloses a control method and device for frame shedding of a cold continuous rolling mill, which mainly adjusts the tension value according to the tension control gain coefficient. However, this patent lacks coordinated control between the control functions during rolling and dynamic calculation of tension. SUMMARY

[0003] The present application provides a dynamic tension control method for cold continuous rolling with a frame shedding function, which can avoid risks and realize the continuity of production under the premise of ensuring the thickness precision of the steel plate. At the same time, after shedding the faulty frame, four-frame continuous rolling is realized, which saves a part of emulsion consumption and power consumption, realizes the purpose of energy saving and consumption reduction, and makes the unit have a certain flexible production capacity.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] A dynamic tension control method for cold continuous rolling with a frame shedding function, a mode selection module selects a "frame shedding" mode, a process control module recalculates the tension of the four frames, the load is distributed to the frames to be worked in proportion, and a basic control module adjusts the tension control strategy. When the i th frame starts the "frame shedding" mode, the tension set value is set to 0, the tension control set value of the i+1 th frame is switched to the tension control set value of the i th frame, the actual values of the outlet tension and the strip thickness of the i-1 th frame are switched to the actual values of the inlet of the i+1 th frame.

[0006] The mode selection module selects the "frame throwing" mode through the basic automation HMI picture and sends it to the process computer, and the process computer marks the corresponding frame as an inactive state.

[0007] The process control module receives the set value calculation application sent by the mode selection module, organizes the rolling strategy, proportionally distributes the load of the five frames to the four frames to be worked, distributes the total reduction rate of rolling to the four frames, calculates the corresponding set value, sets the front and rear tension of the thrown frame to be equal to the rear tension of the thrown frame, sets the roll gap set value to be in an open state, sets the reduction rate, front slip value and the like to be 0, and sends the tension set value of the four frames to the basic automation.

[0008] The basic control module re-adjusts the tension control strategy and the inlet and outlet set values, including the following steps:

[0009] (1) When the i-th frame starts the "frame throwing" mode, the tension set value of the i-th frame is set to 0, and the actual value of the outlet tension of the i-th frame is switched to 0, so that it does not participate in tension control;

[0010] (2) In the tension control between the working frames, the tension control set value of the i+1-th frame is switched to the tension control set value of the i-th frame, and the P (proportion) and I (integral) parameters of the tension PI controller of the i+1-th frame are dynamically modified to be calculated from the parameters of the i-th frame to the parameters of the i-1-th frame, including: the front slip calculation target value of the i-1-th frame, the front slip deviation value, the working roll diameter, the rolling force actual value, the outlet thickness set value, the plastic coefficient of the rolled piece, the elastic modulus of the i-1-th frame of the rolling mill, the frame speed target value, and the frame speed actual value;

[0011] (3) The actual values of the outlet tension and the outlet strip thickness of the i-1-th frame are switched from the inlet measurement value of the i-th frame to the inlet measurement value of the i+1-th frame;

[0012] (4) The tension control process of the i+2-th frame only changes the upper limit amplitude value of the driving control tension and has no effect on the tension set and control of the i-2-th frame and the remaining frames; the manual intervention control is cancelled and is forced to be 0, the tension establishment and tension loss judgment conditions are switched, and the i+1-th frame is used for logical judgment.

[0013] Compared with the prior art, the beneficial effects of the present application are:

[0014] 1) Under the premise of ensuring the tension thickness accuracy of the steel plate, the faulty frame is thrown away to continue rolling, the risk of production stoppage can be avoided, and the continuity of production is realized;

[0015] 2) After the faulty frame is thrown away, four-frame continuous rolling is realized, a part of the emulsion consumption and power consumption is saved, the purpose of energy saving and consumption reduction is realized, and the unit has a certain flexible production capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of the control method of the present invention.

[0017] Figure 2 It is a control principle diagram of the present invention.

[0018] Figure 3 This is a rolling state diagram of the second stand and the swing stand according to the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0020] See Figure 1 , which is a flow chart of the control method of the present invention. The present invention provides a dynamic tension control method for cold tandem rolling in a stand-swinging mill. The mode selection module selects the "stand-swinging" mode, the process control module recalculates the tensions of the four stands, and the load is proportionally distributed to the stands to be operated. The basic control module adjusts the tension control strategy. When the "stand-swinging" mode is activated for the i-th stand, the tension set value is set to 0, the tension control set value of the i+1th stand is switched to the tension control set value of the i-th stand, the outlet tension and strip thickness actual values ​​of the i-1th stand are switched to the inlet actual values ​​of the i+1th stand.

[0021] In the mode selection module, when the second rack enters the rack-swinging mode, the selection is sent to the process computer through the basic automation HMI screen, and the process computer marks the corresponding second rack as inactive;

[0022] The process control module receives the set value calculation application sent by the mode selection module. When the interface between process automation and basic automation ensures normal communication, it receives the "stand-off" signal of the second frame, skips the load distribution of the second frame, and sets the corresponding pressure reduction of the second frame to 0, that is, no tension load is allocated to the faulty frame, and the loads of the five frames are proportionally distributed to the other four frames to be worked normally. The total reduction rate of rolling is distributed by the four frames, and the corresponding set values ​​are calculated. The front and rear tensions of the thrown frame are equal to the rear tension of the thrown frame, and the roll gap setting value is in the open state. The reduction rate, forward slip value, etc. are set to 0. The tension setting values ​​of the four frames are sent to the basic automation. The frame tension setting calculation formula during stand-off rolling is:

[0023] T i =f(f i ,R wi ,F i ,△H i ,G m ,G si ,V i )

[0024] f = f (T, V, G, R, F, H, H`, H``, H``` i front slip value, R wi work roll diameter, F i mill force, AH i mill gap, G m strip plastic coefficient, G si elastic modulus of the ith stand, V i the ith stand speed, i = 1-5

[0025] see Figure 2 , the basic control module re-adjusts the tension control strategy, the inlet and outlet set values, including the following steps:

[0026] (1) in the high speed rolling process of more than 60m / min, the rolling width is required to be 0-1620mm, the rolling thickness is 0.65-9mm, the yield strength of the rolling stand is 300-350Mpa, and the total reduction of the rolling stand is 73%-83%; when the second stand starts the "throwing stand" mode, the second stand tension set value is set to 0, and the actual value of the second stand outlet tension is switched to 0, so that it does not participate in the tension control, at this time, the second stand actual speed V`2=0, V`1=V3;

[0027] (2) in the tension control between the working stands, the actuator of the tension control system is a hydraulic pressure device, the tension control set value of the third stand is switched to the tension control set value of the second stand, and the P(proportion) and I(integral) parameters of the third stand tension PI controller are dynamically modified to be switched to the parameters of the first stand, including: the front slip calculation target value of the first stand, the front slip deviation value, the work roll diameter, the rolling force actual value, the outlet thickness set value, the plastic coefficient of the rolled piece, the elastic modulus of the first stand of the rolling mill, the stand speed target value, the stand speed actual value, the actual tension value obtained by comparing the measured value of the tension meter after the tension feedback processing of the first stand with the set tension, and the tension deviation value. If the tension deviation value exceeds the allowed range of the tension deviation, the hydraulic roll gap control function outputs a roll gap adjustment amount;

[0028] (3) the actual values of the outlet tension and the outlet strip thickness of the first stand are switched from the inlet measured value of the second stand to the inlet measured value of the third stand, and the actual tension of the first stand outlet is equal to the set tension of the third stand inlet T`1=T3;

[0029] (4) in the tension control process of the ith+2 stand, only the upper limit amplitude value of the driving control tension is changed, and there is no influence on the tension set and control of the ith-2 stand and the remaining stands; the manual intervention control is cancelled and is forced to be 0, the tension establishment and tension loss judgment conditions are switched, and the ith+1 stand is used for logical judgment.

[0030] See Figure 3 , after the second stand is set to "throw stand" mode, the roll gap is opened to 8mm, and the set speed and actual speed of the second stand are both 0.

[0031] The following examples are implemented on the basis of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples. The methods used in the following examples are all conventional methods unless otherwise specified.

[0032]

EXAMPLE

[0033] As Figure 2 shown, the cold rolling stand runs from the first stand to the fifth stand, when the second stand fails, the mode selection module sets the second stand to "throw stand" mode, and assigns the load to skip the second stand, sets the corresponding reduction of the second stand to 0, that is, does not assign the tension load to the failed stand, and assigns the load of the five stands to the other four normal working stands in proportion, the total reduction rate of rolling is assigned by the four stands, the corresponding set value is calculated, the front and rear tensions of the thrown stand are equal and are the rear tension of the thrown stand, the roll gap set value is set to the open state, the reduction rate, front slip value and the like are set to 0, and the tension set value of the four stands is sent to the basic automation, the stand tension set calculation formula when the stand is rolled is:

[0034] T i =f(f i ,R wi ,F i ,△H i ,G m ,G si ,V i )

[0035] In the formula, f i is the front slip value, R wi is the work roll diameter, F i is the stand rolling force, △H i is the stand thickness difference, G m is the plastic coefficient of the strip, G si is the elastic modulus of the i-th stand of the rolling mill, V i is the speed of the i-th stand, and i=1-5.

[0036] If the second stand is cast off, the first stand tension control: the outlet tension value calculated by the control gain is switched from the second stand outlet to the third stand outlet; the second stand tension control: the deviation of the actual measured value of the first stand outlet tension is set to 0, the additional acceleration when the rolling wedge is set to 0, the fast stop signal generated by the shielding acceleration overrun is shielded, and the tension control set value is from the speed slope; the third stand tension control: the front slip, the front slip deviation, the work roll diameter, and the actual rolling force parameters of the first stand are used to calculate the tension control gain of the second stand, and the set speed of the front stand is converted from two stands to one stand; the fourth stand tension control: the front two stand speeds in the upper limit LU of the transmission tension control are converted from the second stand to the one stand speed.

Claims

1. A dynamic tension control method for cold rolling mill stand rolling, characterized in that: The mode selection module selects the "rack-swing" mode. The process control module recalculates the tension of the four racks and distributes the load proportionally to the racks to be operated. The basic control module adjusts the tension control strategy. When the "rack-swing" mode is activated for the i-th rack, the tension setpoint is set to 0, the tension control setpoint of the i+1th rack is switched to the tension control setpoint of the i-th rack, the actual values ​​of the outlet tension and strip thickness of the i-1th rack are switched to the actual values ​​of the inlet of the i+1th rack. The process control module receives the set value calculation application sent by the mode selection module, organizes the rolling strategy, distributes the load of the five frames to the four frames to be worked in proportion, and the total rolling reduction rate is distributed by the four frames. The corresponding set values ​​are calculated, the front and rear tensions of the thrown frame are equal, and both are the back tensions of the thrown frame. The roll gap setting value is open, the reduction rate and the forward slip value are set to 0, and the tension setting values ​​of the four frames are sent to the basic automation. The frame tension setting calculation formula during rolling of the thrown frame is: ； Where, is the rack tension setting value when the i-th rack is rolling, is the forward sliding value of the i-th rack, is the diameter of the working roll of the i-th stand, is the rolling force of the stand i, is the thickness difference of the i-th rack, is the plasticity coefficient of the strip steel of the i-th rack, Elastic modulus of the i-th stand of the rolling mill, The speed of the i-th rack, i=1~5; The basic control module readjusts the tension control strategy, inlet and outlet set values, including the following steps: (1) When the i-th rack starts the "rack-swinging" mode, the i-th rack tension setting value is set to 0, and the i-th rack outlet tension actual value is switched to 0 at the same time, so that it does not participate in tension control; (2) In the tension control between working stands, the tension control setting value of the i+1 stand is switched to the tension control setting value of the i stand, and the proportional and integral parameters of the tension PI controller of the i+1 stand are dynamically modified to be calculated from the parameters of the i stand and switched to the parameters of the i-1 stand, including: the forward slip calculation target value of the i-1 stand, the forward slip deviation value, the working roll diameter, the actual rolling force value, the outlet thickness setting value, the plastic coefficient of the rolled piece, the elastic modulus of the i-1 stand of the rolling mill, the stand speed target value, and the stand speed actual value; (3) The actual values ​​of the outlet tension and outlet strip thickness of the i-1th rack are switched from the inlet measurement values ​​of the i-th rack to the inlet measurement values ​​of the i+1th rack; (4) During the tension control process of the i+2 rack, only the upper limit value of the transmission control tension is changed, and the tension setting and control of the i-2 rack and the remaining racks are not affected; the manual intervention control is canceled and forced to 0, and the tension establishment and tension loss judgment conditions are switched, and the i+1 rack is used for logical judgment.

2. The method for dynamic tension control of cold tandem rolling mill according to claim 1, characterized in that: The mode selection module selects the "rack-dropping" mode through the basic automation HMI screen and sends it to the process computer, which then marks the corresponding rack as inactive.

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