CN118122794A - Strip steel threading method of finishing mill - Google Patents
Strip steel threading method of finishing mill Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title abstract description 68
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Abstract
The application discloses a strip steel threading method of a finishing mill. The method comprises the following steps: determining the second flow of each rack and the initial threading speed of each rack according to a second model of a hot rolling production line and a second flow balance principle; according to a preset speed lifting ratio and the initial threading speed of the 1 st frame, determining the high-speed threading speed of the 1 st frame, determining the number of frames for implementing high-speed threading, and constructing a high-speed threading model; and determining the deceleration rate of the high-speed threading machine frame according to the number of the high-speed threading machine frames and the high-speed threading speed of the 1 st machine frame. The strip threading method of the finishing mill strip steel can improve the threading speed of the finishing mill strip steel, thereby improving the yield of the whole hot continuous rolling production line.
Description
Technical Field
The application relates to the technical field of steel rolling, in particular to a strip steel threading method of a finishing mill.
Background
In the existing hot continuous rolling model, the threading speed of a finishing mill is calculated by a secondary model according to parameters such as the technological requirement of strip steel, the equipment production capacity, the actual finish rolling inlet temperature of strip steel and the like. However, in the actual production process, the strip steel between the frames of the finishing mill needs to meet the second flow balance principle, so that the strip threading speed of the front frame is often about one tenth of that of the tail frame. The speed of the strip steel from the start of the flying shears to the entry of the strip steel into the finishing mill is usually required to be matched with the speed of the strip steel entering the first stand, so that the finish rolling time is prolonged, meanwhile, the pure rolling time of the finishing mill is too long, the head temperature of the strip steel is excessively reduced, and the self-learning and the production stability of the secondary model are not facilitated. These problems greatly restrict the improvement of the rolling speed of the finishing mill and influence the yield of the whole hot continuous rolling production line.
Disclosure of Invention
The embodiment of the application provides a strip threading method of a finishing mill strip steel, which can improve the threading speed of the finishing mill strip steel, thereby improving the yield of the whole hot continuous rolling production line.
The embodiment of the application provides a strip threading method of a finishing mill strip steel, which comprises the following steps: determining the second flow of each rack and the initial threading speed of each rack according to a second model of a hot rolling production line and a second flow balance principle; according to a preset speed lifting ratio and the initial threading speed of the 1 st frame, determining the high-speed threading speed of the 1 st frame, determining the number of frames for implementing high-speed threading, and constructing a high-speed threading model; and determining the deceleration rate of the high-speed threading machine frame according to the number of the high-speed threading machine frames and the high-speed threading speed of the 1 st machine frame.
According to one aspect of the embodiment of the present application, according to the number of frames carrying out high-speed threading and the high-speed threading speed of the 1 st frame, the step of determining the deceleration rate of each frame carrying out high-speed threading includes the step of decelerating the head of the strip steel to a high-speed threading speed before loading the 1 st frame, decelerating the head of the strip steel to a preset deceleration rate after loading the 1 st frame, and decelerating the head of the strip steel to a final threading speed after loading the n-1 st frame and before loading the n-th frame.
According to one aspect of the embodiment of the present application, the steps of determining the high-speed threading speed of the 1 st frame, determining the number of frames implementing the high-speed threading, and constructing the high-speed threading model include obtaining a maximum value of the last frame threading speed, a minimum value of the last frame threading speed, a maximum value of the intermediate blank thickness, a minimum value of the intermediate blank thickness, a maximum value of the finished product thickness, and a minimum value of the finished product thickness according to the preset speed lifting ratio and the initial threading speed of the 1 st frame.
According to one aspect of an embodiment of the present application, the racks that implement high-speed threading include a1 st rack, a2 nd rack, a 3 rd rack, and a4 th rack.
According to an aspect of the embodiment of the present application, the steps of determining the high-speed threading speed of the 1 st frame, determining the number of frames implementing the high-speed threading, and constructing the high-speed threading model include constructing a speed factor setting model and confirming the first limit clipping according to the preset speed increasing ratio and the initial threading speed of the 1 st frame.
According to one aspect of an embodiment of the present application, constructing the speed factor setting model and the validation of the first limit clipping includes determining the high-speed threading coefficients by equations (1) - (4):
α＝1+δ*β (1)
Wherein W MAX is the maximum value of the finished product width, the unit is mm, W set is the set value of the finished product width, the unit is mm, W MIN is the minimum value of the finished product width, the unit is mm, H MAX is the maximum value of the finished product thickness, the unit is mm, H SET is the set value of the finished product thickness, the unit is mm, H MIN is the minimum value of the finished product thickness, the unit is mm, alpha is the multiplication gain coefficient of the high-speed threading, delta is the width factor of the high-speed threading, delta width is the width factor correction coefficient, beta is the thickness factor of the high-speed threading, beta thick is the thickness factor correction coefficient, K is the high-speed factor limit, The high-speed threading coefficient is expressed in%.
According to one aspect of the embodiment of the present application, according to a preset speed increasing ratio and an initial threading speed of the 1 st frame, the steps of determining a high-speed threading speed of the 1 st frame, determining the number of frames implementing high-speed threading, and constructing a high-speed threading model include performing a second limit checking on a high-speed threading factor of the last frame, wherein the high-speed threading speed of the last frame is obtained by multiplying the threading speed normally set by the high-speed threading coefficient.
According to one aspect of an embodiment of the present application, the second limit checking for the high-speed threading factor of the last chassis is performed by equation (5):
in the case of V F-last Quick speed ≤VF-last Setting up , the high-speed threading speed of the last frame is V F-last Setting up ;
in the case of V F-last Quick speed ＞VF-last Maximum value , the high-speed threading speed of the last frame is V F-last Maximum value ;
Wherein V F-last Quick speed is the high-speed threading speed of the end frame in the high-speed threading mode, the unit is m/s, V F-last Setting up is the normal set threading speed of the end frame, the unit is m/s, V F-last Maximum value is the maximum threading speed of the end frame, the unit is m/s, The high-speed threading coefficient is expressed in%.
According to one aspect of the embodiment of the present application, the steps of determining the high-speed threading speed of the 1 st frame, determining the number of frames implementing the high-speed threading, and constructing the high-speed threading model include performing a second limit limiter check on the full frame high-speed threading factor according to the preset speed hoisting ratio and the initial threading speed of the 1 st frame.
According to one aspect of an embodiment of the present application, the second limit checking for the full frame high speed threading factor is performed by equation (6):
V Fi Quick speed is the high-speed threading speed of the ith rack, the unit is m/s, V F-last Quick speed is the high-speed threading speed of the last rack in the high-speed threading mode, the unit is m/s, h Fi is the calculated thickness of the intermediate blank at the outlet of the ith rack, the unit is mm, and h F-last is the calculated thickness of the intermediate blank at the last rack, and the unit is mm;
In the case of V Fi Quick speed ≥VFi Maximum value , the high-speed threading speed of the ith chassis is replaced with the maximum threading speed of the ith chassis, and the high-speed threading speed of the last chassis is calculated again by equation (5).
According to the embodiment of the application, the high-speed threading speed of the 1 st stand is determined according to the preset speed lifting proportion and the initial threading speed of the 1 st stand, the number of the stands for implementing high-speed threading is determined, and a high-speed threading model is constructed, so that the threading speed of the finishing mill is improved within the range of the existing rolling mill equipment. In addition, according to the number of the racks for carrying out high-speed threading and the high-speed threading speed of the 1 st rack, the embodiment of the application determines the speed reduction rate of the racks for carrying out high-speed threading, improves the head temperature of strip steel, and ensures that the head temperature of strip steel in the strip steel is in a proper range in the rolling process, thereby improving the threading stability, reducing the labor intensity of operators, further improving the threading speed of the strip steel of the finishing mill, and further improving the yield of the whole hot continuous rolling production line.
Drawings
Features, advantages, and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of the running speed of a strip in a finishing mill according to an embodiment of the present application.
Wherein:
10. a flying shear shearing area; 20. a fine descaling zone; 30. a high-speed threading area; 40. reducing a starting point; 50. a deceleration zone; 60. a deceleration completion point; 70. and (5) a normal threading area.
Detailed Description
Features and exemplary embodiments of various aspects of the application are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the application. It will be apparent, however, to one skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the application by showing examples of the application. In the drawings and the following description, at least some well-known structures and techniques have not been shown in detail in order not to unnecessarily obscure the present application; also, the dimensions of some of the structures may be exaggerated for clarity. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
In the present application, the terms "first," "second," and the like are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
It should be noted that, the hot continuous rolling production line in the embodiment of the application comprises a flying shear shearing process, a fine descaling process and a rolling process. The rolling time in the embodiment of the application is the time required for the head of the strip steel to enter the 1 st stand and the tail of the strip steel to go out of the last stand, and the rolling time can be also called finish rolling pure rolling time. The rolling process refers to the process from the head of the strip steel to the 1 st stand to the tail of the strip steel to the last stand. The threading process in the embodiment of the application refers to the process from the head of the strip steel entering the 1 st frame to the head of the strip steel passing through the last frame.
The embodiment of the application provides a strip threading method of a finishing mill strip steel, which comprises the following steps:
determining the second flow of each rack and the initial threading speed of each rack according to a second model of a hot rolling production line and a second flow balance principle;
According to a preset speed lifting ratio and the initial threading speed of the 1 st frame, determining the high-speed threading speed of the 1 st frame, determining the number of frames for implementing high-speed threading, and constructing a high-speed threading model;
And determining the deceleration rate of the high-speed threading machine frame according to the number of the high-speed threading machine frames and the high-speed threading speed of the 1 st machine frame.
According to the embodiment of the application, the high-speed threading speed of the 1 st stand is determined according to the preset speed lifting proportion and the initial threading speed of the 1 st stand, the number of the stands for implementing high-speed threading is determined, and a high-speed threading model is constructed, so that the threading speed of the finishing mill is improved within the range of the existing rolling mill equipment. In addition, according to the number of the racks for carrying out high-speed threading and the high-speed threading speed of the 1 st rack, the embodiment of the application determines the speed reduction rate of the racks for carrying out high-speed threading, improves the head temperature of strip steel, and ensures that the head temperature of strip steel in the strip steel is in a proper range in the rolling process, thereby improving the threading stability, reducing the labor intensity of operators, further improving the threading speed of the strip steel of the finishing mill, and further improving the yield of the whole hot continuous rolling production line.
The principle of second flow balance of the strip steel refers to the equal mass of the strip steel passing through each rack in unit time.
The second flow calculation formula of the strip steel can comprise: and taking a certain frame in the rolling process, wherein the speed of the strip steel at the outlet of the frame is V, the thickness of the strip steel at the outlet of the frame in a thermal state is H, the width of the strip steel at the outlet of the frame in the thermal state is W, and calculating the second flow m of the strip steel at the outlet of the frame according to m=V×H×W (formula 1-1).
In some alternative embodiments, the step of determining the deceleration rate of each of the high-speed threading machine frames may include decelerating the running speed of the strip head to the high-speed threading speed before loading the 1 st machine frame, decelerating the running of the strip head to the final threading speed after loading the 1 st machine frame, and decelerating the running of the strip head to the final threading speed after loading the n-1 st machine frame and before loading the n-th machine frame, based on the number of high-speed threading machine frames and the high-speed threading speed of the 1 st machine frame.
FIG. 1 is a schematic diagram of the running speed of a strip in a finishing mill according to an embodiment of the present application. When the 7-frame finishing mill is adopted for rolling, CS is a shearing machine, and the running speed of the strip steel in the flying shear shearing area 10 is the shearing speed of the flying shear. FSB is a fine descaler in which the strip is typically run at a higher speed in the fine descaling 20, i.e., the strip is typically run at a higher speed in the fine descaling 20 than in the high speed threading 30. The 1 st frame F1, the 2 nd frame F2, the 3 rd frame F3, the 4 th frame F4, the 5 th frame F5, the 6 th frame F6 and the 7 th frame F7 are all finishing frames, and the region where the finishing frames are located is a finishing zone, wherein the finishing zone can be divided into a high-speed threading zone 30, a deceleration starting point 40, a deceleration zone 50, a deceleration finishing point 60 and a normal threading zone 70.
As can be seen from fig. 1, after loading the 1 st stand, the strip runs at a high threading speed, between the 1 st stand and the 4th stand, at a preset deceleration rate, and before the strip head reaches the 4th stand, at a normal threading speed. The term "loading" is the moment when the strip head enters a certain stand, i.e. the strip head bites into the stand, which may also be referred to as the stand's pressure sensor detects a rolling force above the rolling threshold.
It should be noted that, the frame for carrying out high-speed threading means that the threading speed of the strip steel in the frame is higher than the normal threading speed thereof, or higher than the threading speed thereof in the normal threading area 70. The speed of the strip is the speed of the strip head, unless otherwise specified.
The preset speed increasing ratio can be determined according to the actual production capacity of the rolling mill, the reaction time of operators and other factors.
In some alternative embodiments, the steps of determining the high-speed threading speed of the 1 st frame, determining the number of frames implementing the high-speed threading, and constructing the high-speed threading model may include obtaining a maximum value of the last frame threading speed, a minimum value of the last frame threading speed, a maximum value of the intermediate blank thickness, a minimum value of the intermediate blank thickness, a maximum value of the finished product thickness, and a minimum value of the finished product thickness according to a preset speed-up ratio and an initial threading speed of the 1 st frame.
In general, when determining the number of frames for performing high-speed threading, reference needs to be made to the reaction time of the operator to adapt the method for threading the strip steel in the finishing mill according to the embodiment of the present application, the reaction time of the operator may be determined according to the proficiency of the operation of the operator, and the reaction time of the operator may be, for example, 0.5 to 1.5s.
The maximum value of the threading speed of the end frame, the minimum value of the threading speed of the end frame, the maximum value of the thickness of the intermediate blank, the minimum value of the thickness of the intermediate blank, the maximum value of the thickness of the finished product and the minimum value of the thickness of the finished product can be determined according to the production capacity of equipment in a production line and the reaction time of operators.
The thickness of the intermediate billet in the embodiment of the application refers to the thickness of the strip steel after rough rolling and before shearing.
Illustratively, when rolling with a 7-stand finishing mill, the last stand is the 7 th stand. At this time, the maximum value of the threading speed of the last frame was 11.5m/s, the minimum value of the threading speed of the last frame was 1.8m/s, the maximum value of the thickness of the intermediate blank was 60mm, the minimum value of the thickness of the intermediate blank was 30mm, the maximum value of the thickness of the finished product was 25.4mm, and the minimum value of the thickness of the finished product was 1.4mm.
In some alternative embodiments, the racks that implement high-speed threading may include a1 st rack, a2 nd rack, a3 rd rack, and a4 th rack.
According to the embodiment of the application, the high-speed threading machine frame is set to be the 1 st-4 th machine frame, so that operators adapt to a strip steel threading method of the finishing mill, the threading efficiency is improved, and the yield of the finishing mill can be improved within the range of the existing finishing mill.
Although the above determination of the number of frames for high-speed threading is based on the case of rolling with a 7-frame finishing mill, the number of frames for high-speed threading may be adaptively increased or decreased when the total number of finishing mills is increased or decreased. The finishing mill in the embodiment of the application can be a 7-frame four-roll finishing mill.
In some alternative embodiments, the steps of determining the high-speed threading speed of the 1 st bay, determining the number of bays implementing high-speed threading, and constructing the high-speed threading model may include constructing a speed factor setting model and confirmation of the first limit clip according to a preset speed increase ratio and the initial threading speed of the 1 st bay.
The embodiment of the application can ensure that the temperature of the head part of the strip steel is in a proper range in the rolling process and the strip threading method is suitable for strip steel with different specifications by constructing the speed factor setting model and confirming the first limit limiting, thereby realizing the improvement of the strip threading speed of the finishing mill in the capacity range of the existing rolling mill equipment.
In some alternative embodiments, constructing the speed factor setting model and the validation of the first limit limiter may include determining the high speed threading coefficients by equations (1) - (4):
α＝1+δ*β (1)
Wherein W MAX is the maximum value of the finished product width, the unit is mm, W set is the set value of the finished product width, the unit is mm, W MIN is the minimum value of the finished product width, the unit is mm, H MAX is the maximum value of the finished product thickness, the unit is mm, H SET is the set value of the finished product thickness, the unit is mm, H MIN is the minimum value of the finished product thickness, the unit is mm, alpha is the multiplication gain coefficient of the high-speed threading, delta is the width factor of the high-speed threading, delta width is the width factor correction coefficient, beta is the thickness factor of the high-speed threading, beta thick is the thickness factor correction coefficient, K is the high-speed factor limit, The high-speed threading coefficient is expressed in%.
The value of the strip steel is the minimum value in alpha and K, the process is the confirmation of the first limit limiting, the strip steel threading speed in each rack can be in a proper range through the confirmation of the first limit limiting, and therefore the strip steel rolling quality can be improved, and the strip threading efficiency is further improved.
Note that, in the embodiment of the present application, the width factor correction coefficient δ width and the thickness factor correction coefficient β thick are both known constants.
The high-speed factor limit K in the formulse:Sub>A (4) can be determined according to the grade of steel, the thickness of se:Sub>A finished product and the width of the finished product, and is exemplified by SPHC-A of the grade of steel, the thickness of the finished product is 1.4-1.6mm, the value of the high-speed factor limit K is 120% when the width of the finished product is less than 1080mm or the width of the finished product is less than 1180 mm.
The high-speed threading limit factor K is required to be adjusted according to the hit rate and self-learning condition of finish rolling after the high-speed threading function is put into the strip steel of each specification on the premise of meeting the reaction time, the equipment production capacity and the process index of operators.
High-speed threading coefficient for ensuring second flow balance principleThe multiplication gain coefficient alpha of high-speed threading and the high-speed factor limit K are common to all frames.
In some alternative embodiments, the steps of determining the high-speed threading speed of the 1 st frame, determining the number of frames implementing the high-speed threading, and constructing the high-speed threading model may include performing a second limit check on the high-speed threading factor of the last frame, wherein the high-speed threading speed of the last frame is obtained by multiplying the threading speed normally set by the high-speed threading coefficient, according to the preset speed-up ratio and the initial threading speed of the 1 st frame.
In some alternative embodiments, the second limit checking for the high-speed threading factor of the last chassis may be performed by equation (5):
in the case of V F-last Quick speed ≤VF-last Setting up , the high-speed threading speed of the last frame is V F-last Setting up ;
in the case of V F-last Quick speed ＞VF-last Maximum value , the high-speed threading speed of the last frame is V F-last Maximum value ;
Wherein V F-last Quick speed is the high-speed threading speed of the end frame in the high-speed threading mode, the unit is m/s, V F-last Setting up is the normal set threading speed of the end frame, the unit is m/s, V F-last Maximum value is the maximum threading speed of the end frame, the unit is m/s, The high-speed threading coefficient is expressed in%.
Under the condition that no special description exists, the high-speed threading speeds are the high-speed threading speeds of the machine frame in the high-speed threading mode.
V F-last Maximum value may be determined based on the capacity of the equipment in the production line and the time of the operator's response. Illustratively, V F-last Maximum value is 11.5m/s.
Illustratively, when the finishing process employs a 7 stand finishing mill, V F-last Quick speed is V F7 Quick speed ,VF-last Setting up and V F7 Setting up ,VF-last Maximum value is V F7 Maximum value .
It should be noted that, in the embodiment of the present application, the speed is a linear speed.
According to the embodiment of the application, the second limit limiting inspection is carried out on the high-speed threading factor of the tail frame, so that the high-speed threading speed of the tail frame can be maximized on the premise of not more than the maximum threading speed of the tail frame, and the threading speed of the tail frame of the finishing mill can be improved within the capacity range of the existing equipment.
In some alternative embodiments, the steps of determining the high-speed threading speed of the 1 st bay, determining the number of bays implementing high-speed threading, and constructing the high-speed threading model may include performing a second limit-limiting check on the full bay high-speed threading factor according to the preset speed-up ratio and the initial threading speed of the 1 st bay.
In some alternative embodiments, the second limit checking for the full frame high speed threading factor may be performed by equation (6):
V Fi Quick speed is the high-speed threading speed of the ith rack, the unit is m/s, V F-last Quick speed is the high-speed threading speed of the last rack in the high-speed threading mode, the unit is m/s, h Fi is the calculated thickness of the intermediate blank at the outlet of the ith rack, the unit is mm, and h F-last is the calculated thickness of the intermediate blank at the last rack, and the unit is mm.
Illustratively, when the finishing process employs a 7 stand finishing mill, V F-last Quick speed is V F7 Quick speed ,hF-last and h F7.
In some alternative embodiments, in the case of V Fi Quick speed ≥VFi Maximum value , the high-speed threading speed of the ith chassis is replaced with the maximum threading speed of the ith chassis, and equation (5) is re-used to calculate the high-speed threading speed of the last chassis.
According to the embodiment of the application, the second limit limiting inspection is carried out on the high-speed threading factors of the whole stand, so that the high-speed threading speed of the whole stand can be maximized on the premise that the high-speed threading speed of the whole stand is not greater than the maximum threading speed of the corresponding stand, and the threading speed of the whole stand of the finishing mill can be improved within the capacity range of the existing equipment.
Illustratively, in the case of V Fi Quick speed ≥VFi Maximum value , the high-speed threading speed of the ith chassis is replaced with the maximum threading speed of the ith chassis, at which time α=v Fi Maximum value /VFi Setting up is set and the recalculated α is brought into equation (5) to calculate the high-speed threading speed of the last chassis, and a second limit-limiting check is performed on the full-chassis high-speed threading factor by equation (6).
In some alternative embodiments, determining the deceleration rate of each of the high-speed threading frames based on the number of frames implementing high-speed threading and the high-speed threading speed of the 1 st frame may include determining a deceleration rate reference frame based on the high-speed threading speed of the last frame.
Illustratively, when rolling with the 7-stand finishing mill, the step of determining the deceleration rate of each of the high-speed threading stands according to the number of stands implementing the high-speed threading and the high-speed threading speed of the 1 st stand may include calculating the deceleration rate of the high-speed threading by the formulas (7) - (8):
FM＝[-0.424*VF-last Quick speed +6.779] (7)
FM＝LIMT(3，6) (8)
FM is a speed reduction speed reference frame, V F-last Quick speed is the high-speed threading speed of the 7 th frame, and the unit is m/s.
It should be noted that, the formula (7) refers to rounding the calculation result, the formula (8) refers to an integer in the range of 3-6 for the deceleration rate completion frame, that is, when the number of finishing mills is 7, if the calculated deceleration rate reference frame is 7, the deceleration rate reference frame is 6, and if the calculated deceleration rate reference frame is 1, the deceleration rate reference frame is 3, and if the calculated deceleration rate reference frame is in the range of 3-6, the deceleration rate reference frame is the nearest integer.
The speed reduction rate reference frame is a speed reduction completion frame, namely the speed reduction process is required to be completed before the head of the strip steel reaches the frame.
In some alternative embodiments, determining the deceleration rate of each of the high-speed threading frames according to the number of frames implementing the high-speed threading and the high-speed threading speed of the 1 st frame may include obtaining the deceleration rate of the high-speed threading according to the high-speed threading speed of the deceleration completion frame, the set speed of the deceleration completion frame, and the inter-frame distance.
In some alternative embodiments, determining the deceleration rate of each of the high-speed threading machine frames according to the number of machine frames implementing high-speed threading and the high-speed threading speed of the 1 st machine frame may include calculating the deceleration rate of the high-speed threading by equation (9):
Wherein L is dec＝LF3F4-LF1_dis-Ldis_F4
D FM Quick speed is the speed reduction rate, the unit is m/s 2,LF3F4, the unit is m, L F1_dis is the distance between the 1 st frame and the speed reduction completion point, the unit is m, L dis_F4 is the distance between the speed reduction completion point and the 4 th frame, the unit is m, V FM is the high-speed threading speed of the 4 th frame, the unit is m/s, V FM Setting up is the normal set threading speed of the 4 th frame, and the unit is m/s.
Under the condition of D FM Quick speed ＞DFM Maximum value , the deceleration rate is D FM Maximum value , and an alarm sign is sent to the secondary machine and operators to remind the secondary machine and operators to reduce the high-speed threading coefficient。
D FM Maximum value may be determined according to equipment limits in the production line.
The "secondary machine" in the embodiments of the present application refers to a secondary control system or a process parameter control system.
The distance from the 1 st stand to the deceleration completion point, i.e., the position where the running speed of the strip reaches the normal running speed, is exemplified by the distance from the center point of the 1 st stand to the center point of the 4 th stand when the deceleration is completed before the 4 th stand.
In the embodiment of the present application, the speed reduction rate between the speed reduction frames is a constant value.
The embodiment of the application takes a finishing mill in a hot continuous rolling production line as a research object, combines a large number of rolling data statistical analysis and field experiments based on the research on a finishing mill threading speed strategy, breaks through the limitation of the conventional technology, and provides a finishing mill strip steel threading method for improving the finishing mill threading speed within the capability range of the existing rolling mill equipment. The head temperature of the strip steel is improved, so that the head temperature of the strip steel is in a proper range in the rolling process of the strip steel, the strip threading stability is improved, and the labor intensity of operators is reduced. The strip steel threading method of the finishing mill can be adapted to strip steel of different specifications by optimizing the strip threading speed control strategy, and the strip threading speed of the finishing mill is improved, so that the yield and the production efficiency of the whole hot continuous rolling production line are improved, the positive pushing effect on the production of iron and steel enterprises is achieved, and a new solution is provided for the sustainable development of the iron and steel industry.
Examples
The present disclosure is more particularly described in the following examples that are intended as illustrations only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art.
Examples 1 to 3
Examples 1-3 employ the high-speed threading model of the present application.
Examples 1-3 each set a multiplication gain factor of 15% calculated according to equations (1) - (9): the frames on which the high-speed threading was performed were 1 st to 4 th frames, and the initial threading speed of F1, the initial threading speed of F7, the high-speed threading speed of F1, the high-speed threading speed of F7, and the deceleration rate were shown in table 1.
TABLE 1
Comparative examples 1 to 3
Comparative examples 1-3 were calculated using conventional two-stage models for the threading speed of each frame.
The rolling conditions of examples 1-3 and comparative examples 1-3 were counted with the same threading speed, and the rolling conditions of examples 1-3 and comparative examples 1-3 are shown in Table 2.
TABLE 2
Average finish rolling time: the time required for the head of the strip steel to enter the 1 st rack and the tail of the strip steel to go out of the last rack.
Average rolling cadence: the time from the previous strip head passing through F1 to the next strip head entering F1.
Number of rolled blocks: the number of samples taken during the experimental study was not related to the rolling capacity of the finishing mill.
As can be seen from Table 2, the strip threading method of the finishing mill provided by the embodiment of the application has the advantages that the strip threading time of finish rolling of strip steel with different steel grades is reduced by 4.27s on average, the strip threading speed of the finishing mill is improved, and the yield and the production efficiency of the whole hot continuous rolling production line can be improved.
While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.
Claims (10)
1. A strip threading method of a finishing mill, comprising:
determining the second flow of each rack and the initial threading speed of each rack according to a second model of a hot rolling production line and a second flow balance principle;
According to a preset speed lifting ratio and an initial threading speed of a1 st rack, determining a high-speed threading speed of the 1 st rack, determining the number of racks for implementing high-speed threading, and constructing a high-speed threading model;
and determining the deceleration rate of the high-speed threading machine frame according to the number of the high-speed threading machine frames and the high-speed threading speed of the 1 st machine frame.
2. The strip threading method of claim 1 wherein the step of determining the deceleration rate of each high speed threading stand based on the number of high speed threading stands and the high speed threading speed of the 1 st stand includes decelerating the strip head to a final threading speed after the 1 st stand is loaded and before the n-1 st stand is loaded at a predetermined deceleration rate after the 1 st stand is loaded.
3. The strip threading method of claim 1 wherein the steps of determining the high speed threading speed of the 1 st stand, determining the number of stands implementing high speed threading, and constructing the high speed threading model based on a preset speed increase ratio and an initial threading speed of the 1 st stand include obtaining a maximum value of the last stand threading speed, a minimum value of the last stand threading speed, a maximum value of the thickness of the intermediate blank, a minimum value of the thickness of the intermediate blank, a maximum value of the thickness of the finished product, and a minimum value of the thickness of the finished product.
4. The strip threading method of claim 1 wherein the frames for performing high speed threading include a1 st frame, a2 nd frame, a 3 rd frame and a 4 th frame.
5. The strip threading method of claim 1 wherein the steps of determining the high speed threading speed of the 1 st stand, determining the number of stands implementing high speed threading, and constructing a high speed threading model based on a preset speed increase ratio and an initial threading speed of the 1 st stand include constructing a speed factor setting model and confirmation of a first limit clip.
6. The finishing mill strip threading method of claim 5 wherein the establishing of the velocity factor set model and the confirmation of the first limit limiter includes determining the high-velocity threading coefficient by equations (1) - (4):
α＝1+δ*β (1)
Wherein W MAX is the maximum value of the finished product width, the unit is mm, W set is the set value of the finished product width, the unit is mm, W MIN is the minimum value of the finished product width, the unit is mm, H MAX is the maximum value of the finished product thickness, the unit is mm, H SET is the set value of the finished product thickness, the unit is mm, H MIN is the minimum value of the finished product thickness, the unit is mm, alpha is the multiplication gain coefficient of the high-speed threading, delta is the width factor of the high-speed threading, delta width is the width factor correction coefficient, beta is the thickness factor of the high-speed threading, beta thick is the thickness factor correction coefficient, K is the high-speed factor limit, The high-speed threading coefficient is expressed in%.
7. The strip threading method of claim 6 wherein the steps of determining the high speed threading speed of the 1 st stand, determining the number of stands implementing high speed threading and constructing a high speed threading model based on a preset speed increase ratio and an initial threading speed of the 1 st stand include performing a second limit check on a high speed threading factor of the last stand, wherein the high speed threading speed of the last stand is obtained by multiplying the threading speed normally set by the high speed threading coefficient.
8. The finishing mill strip threading method of claim 7 wherein the second limit checking of the high speed threading factor of the last stand is performed by equation (5):
in the case of V F-last Quick speed ≤VF-last Setting up , the high-speed threading speed of the last frame is V F-last Setting up ;
in the case of V F-last Quick speed ＞VF-last Maximum value , the high-speed threading speed of the last frame is V F-last Maximum value ;
Wherein V F-last Quick speed is the high-speed threading speed of the end frame in the high-speed threading mode, the unit is m/s, V F-last Setting up is the normal set threading speed of the end frame, the unit is m/s, V F-last Maximum value is the maximum threading speed of the end frame, the unit is m/s, The high-speed threading coefficient is expressed in%.
9. The strip threading method of claim 8 wherein the steps of determining the high speed threading speed of the 1 st stand, determining the number of stands implementing high speed threading and constructing a high speed threading model based on a preset speed increase ratio and an initial threading speed of the 1 st stand include performing a second limit limiting check on the full stand high speed threading factor.
10. The finishing mill strip threading method of claim 9 wherein the second limit checking of the full frame high speed threading factor is performed by equation (6):
V Fi Quick speed is the high-speed threading speed of the ith rack, the unit is m/s, V F-last Quick speed is the high-speed threading speed of the last rack in the high-speed threading mode, the unit is m/s, h Fi is the calculated thickness of the intermediate blank at the outlet of the ith rack, the unit is mm, and h F-last is the calculated thickness of the intermediate blank at the last rack, and the unit is mm;
In the case of V Fi Quick speed ≥VFi Maximum value , the high-speed threading speed of the ith chassis is replaced with the maximum threading speed of the ith chassis, and the high-speed threading speed of the last chassis is calculated again by equation (5).
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