CN109675933B - Rod water-cooling closed-loop control process method and control system - Google Patents
Rod water-cooling closed-loop control process method and control system Download PDFInfo
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Abstract
The invention relates to a bar water-cooling closed-loop control process method and a control system, wherein the bar water-cooling closed-loop control process method comprises the following steps: collecting temperature information before and after bar material finish rolling; and carrying out accurate rolling and cooling control on the processes of bar rolling and steel bar splitting rolling according to a through water cooling and temperature feedback closed-loop adjusting method. The process method can realize the stability of controlled rolling temperature and controlled cooling process, reduce the alloy consumption of the bar, solve the problems of water-cooling black ring tissues on the surface of the bar, poor hardness of the core surface and the like caused by water penetration, and is beneficial to improving the production benefit of a steel mill. The method provides a technical idea for accurately controlling the cooling process for cooling the special steel bars such as gears after rolling, can solve the problems of large crystal grains, cold shear cracking and the like caused by the unstable cooling process of the special steel bars after rolling, and is beneficial to improving the product quality and promoting the smooth production of steel mills on the premise of reducing the production cost of the bars.
Description
Technical Field
The invention relates to the technical field of rolling control and cooling control in steel rolling production, in particular to a rod water-cooling closed-loop control process method and a control system.
Background
The closed-loop control has wide application in the field of metallurgical engineering, such as dynamic adjustment of the consumption of coal gas by a blast furnace hot blast stove at a constant target temperature, automatic water distribution for continuous casting secondary cooling, dynamic adjustment of air-coal combustion ratio of a heating furnace and the like. However, in the field of rolling control and cooling control in steel rolling production, the application of the closed-loop control method in the prior art is still imperfect.
Meanwhile, the State quality inspection Bureau and the State standards Commission have officially released GB/T1499.2-2018 Steel for reinforced concrete part 2: the new standard of hot-rolled ribbed steel bars not only stipulates the upper limit requirement of chemical components, but also stipulates the metallographic structure: when the macroscopic metallographic phase of the sample has a closed ring with obvious contrast different from that of the internal area on the periphery of the base circle of the cross section, the macroscopic metallographic phase of the sample is directly judged to be unqualified and does not need to be subjected to hardness test; and when the macroscopic metallographic phase of the sample has an unclosed ring with the contrast different from that of the inner area on the periphery of the base circle of the cross section, performing a hardness comparison test on the skin and the core of the base circle, and judging that the sample is unqualified if the difference between the hardness values of the skin and the core of the base circle is more than 40 HV. This is a great challenge for enterprises (mostly old small rolling mill production lines) which adopt the conventional process for production, because many enterprises adopt the rough controlled cooling process after rolling for a long time, which causes the problems of the supercooled structure on the surface of the steel bar and the overhigh yield ratio. In order to meet the requirements of new standards, the application effect of the controlled rolling and cooling process has to be weakened, and the structural performance requirements of finished materials are ensured by improving the microalloy element components of the bars such as Nb and V, so that the production cost is improved, the price of Nb and V alloys is increased, and great pressure is brought to steel mills. For enterprises adopting controlled rolling and controlled cooling production, the macroscopic metallographic phase also needs to be controlled by adopting controlled rolling and controlled cooling, so that the closed ring on the base circle section is avoided, the Vickers hardness test is also listed as a conventional project, and the inspection and test work is greatly increased. In conclusion, a stable cooling model and a stable process are urgently needed for steel to ensure the normal structure of the bar.
In addition, in the steel rolling production process, the conventional temperature measuring device is an infrared point type temperature measuring instrument, the number of the temperature measuring instruments needs to be increased and the positions of the temperature measuring instruments need to be changed for bars moving at a high speed and a plurality of bars after being cut, test data are screened, and particularly, if the outlet position of a finished product production line is bounced and fluctuated, the temperature signal of each bar is difficult to detect, and the normal production of the bars is influenced.
Disclosure of Invention
In view of this, the present invention provides a rod water-cooling closed-loop control method and a control system to overcome the defects of the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme: a bar water-cooling closed-loop control process method,
the rod water-cooling closed-loop control process method comprises the following steps:
collecting temperature information before and after bar material finish rolling;
and performing accurate rolling and cooling control on the conventional bar rolling and splitting rolling processes according to a through water cooling and temperature feedback closed-loop adjusting method.
Optionally, the collecting of temperature information before and after bar finish rolling includes:
the method comprises the steps of utilizing a thermal imager to shoot a temperature field for bars before finish rolling, carrying out temperature data acquisition, and carrying out regional editing and positioning on the temperature field on the formed temperature field according to actual conditions of conventional rolling and splitting rolling, thereby forming multi-path data output, so that accurate temperature control of a water cooler on each bar subjected to conventional rolling and splitting rolling is realized through a flow-temperature cooling model.
Optionally, the thermal imager collects temperature field data information in two ways: one is line scanning and the other is area scanning. The thermal imaging device needs to be arranged and installed according to field conditions, the shooting angle is selected to be-45 degrees at a good-view and non-shielding position according to the resolution of a shot image, and a focal length lens of 85 mm-500 mm is selected according to the distance between the installation position and a production line to realize long-distance shooting. The method comprises the steps of installing a thermal imager, collecting data, considering multi-line segmentation, identifying the steel passing position and collecting the steel temperature at the position when the single-line, two-line, three-line, four-line or five-line segmentation is carried out by adopting a mode of combining temperature identification and image identification, transmitting the collected temperature data in a synchronous single-signal, two-signal, three-signal, four-signal or five-signal mode, and carrying out independent temperature closed-loop control on each signal respectively.
Optionally, a one-way air water intercepting cooler with the length of 1m-2m is adopted for pre-water passing treatment before the bar is finish rolled so as to cool the surface temperature of the bar to a target temperature and enable the temperature difference between the core surface and the surface of the bar to be less than 30 ℃.
Optionally, the temperature of the rod after pre-water treatment before finish rolling is controlled to be 70-100 ℃ higher than the temperature of Ar 1.
Optionally, after the bar is finish rolled, a water cooler group is adopted for water passing treatment, and after the water passing treatment, the temperature of the bar on a cooling bed is maintained to be 40-70 ℃ below the Ar1 temperature;
the water cooler group consists of 6-8 one-way air intercepting water coolers which are connected in front and back and is used for realizing sectional cooling of the bar;
the length of each one-way air intercepting water cooler is 2m, and each one-way air intercepting water cooler can be cooled to 40-50 ℃.
Optionally, 6-8 one-way gas water intercepting coolers in the water cooler group can be independently controlled to be opened and closed, the working states of any two one-way gas water intercepting coolers are not affected with each other, and the temperature drop generated by each one-way gas water intercepting cooler is smaller than a preset temperature drop threshold value so as to meet the technical requirement of rod material water penetrating.
Optionally, the method further includes:
and simulating the core surface temperature curve of the rod in the whole rolling and water cooling process by using DEFORM software, and determining the layout of the water cooler by combining a material phase change continuous transition CCT curve.
The invention also provides a rod water-cooling closed-loop control system, which comprises:
the production management subsystem, the coordination subsystem and the rolling line water cooling control subsystem;
the production management subsystem is used for carrying out unified management on the whole control system, and comprises: a server and a first operator station;
the coordination subsystem includes: the communication master station and the second operation station;
the rolling line water cooling control subsystem comprises: the communication slave station is used for establishing communication connection with the communication master station;
the rolling line water-cooling control subsystem is used for carrying out water-through cooling and temperature closed-loop control on bars before and after finish rolling, and remotely transmitting production operation data to the server through the communication slave station and the communication master station; the rolling line water cooling control subsystem further comprises: at least one cooling section;
each cooling section is provided with: the device comprises a water cooler, an infrared thermometer, a pressure gauge, a flow meter and a pneumatic regulating valve, wherein the pneumatic regulating valve is used for carrying out PID automatic regulation control on the water cooler.
Optionally, the infrared thermometer is an infrared thermal imager, and is used for collecting the temperature of the rolled and cooled bar in real time;
according to the requirements of variety specification size and temperature, the infrared thermal imager is an online infrared thermal imager with 640x480 or 320x240 resolution.
By adopting the technical scheme, the bar water-cooling closed-loop control process method comprises the following steps: collecting temperature information before and after bar material finish rolling; and carrying out accurate rolling and cooling control on the processes of bar rolling and steel bar splitting rolling according to a through water cooling and temperature feedback closed-loop adjusting method. The process method can realize the stability of the controlled rolling temperature and the controlled cooling process and reduce the alloy consumption of the bar by accurately controlling the pre-water-penetrating process and the finish rolling temperature before finish rolling, the water-penetrating process after rolling and the temperature of the cooling bed after water penetrating; the invention adopts one or more one-way air-intercepting coolers to realize sectional cooling of the bar, avoids the abnormal structure and performance fluctuation on the surface of the bar, solves the problems of water-cooled black ring structure on the surface of the bar, poor hardness of the core surface and the like caused by water penetration, and is beneficial to improving the production benefit of a steel mill. In addition, the method provides a technical idea for accurately controlling the cooling process for the post-rolling cooling of the special steel bars such as gears and non-adjusting bars, and can solve the problems of large crystal grains, core bainite, martensite structure, large structural stress, steel bending, cold shear cracking and the like caused by the unstable post-rolling cooling process of the special steel bars.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a bar water-cooling closed-loop control process method according to an embodiment of the present invention;
FIG. 2 is a model diagram of the regulation relationship of Q (flow rate variation) -T (temperature) provided by an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a rod water-cooling closed-loop control system according to an embodiment of the present invention.
In the figure: 1. a production management subsystem; 11. a server; 12. a first operating station; 2. a coordination subsystem; 21. a communication master station S7-300 PLC; 22. a second operator station; 3. a rolling line water cooling control subsystem; 31. a communication slave station; 32. an infrared thermometer; 33. a pressure gauge; 34. a flow meter; 35. a pneumatic regulating valve; 4. other PLC stations.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Fig. 1 is a schematic flow chart of a bar water-cooling closed-loop control process method according to an embodiment of the present invention.
As shown in fig. 1, the rod water-cooling closed-loop control process method according to the embodiment includes:
s1: collecting temperature information before and after bar material finish rolling;
s2: and carrying out accurate rolling and cooling control on the processes of bar rolling and steel bar splitting rolling according to a through water cooling and temperature feedback closed-loop adjusting method.
In this embodiment, a temperature control target after the rod controlled rolling and controlled cooling is controlled by stages, and an automatic regulation control system combining fuzzy control and traditional control is established by taking a cooling water flow regulating valve as a control object to dynamically regulate cooling water flow and pressure on line in real time, so that a small deviation between the actual temperature of a finish rolling inlet and an upper cooling bed of the rod after the rod is controlled rolling and controlled cooling in stages and a target set value is controlled.
The cooling water regulating valve of the automatic regulating and controlling system has two modes of constant flow control and constant temperature control, the constant flow control mode can be adopted in the early stage of production and during maintenance, the constant flow control mode is switched to the constant temperature control mode during stable production, and the target temperature after water cooling is manually set. When the temperature acquisition result is close to the actually measured steel temperature and other parameters such as flow, pressure and the like are accurate and correct, the temperature acquisition module is put into the automatic temperature adjustment module, the input parameters and the control result of the automatic temperature adjustment module are recorded, and the parameters are continuously corrected and self-learned through a relation list of the input parameters and the results; and the system normally operates, and when the deviation generated by the temperature set value and the temperature process value exceeds the set range of the system, the regulating valve starts to automatically regulate to finish the automatic control process of the temperature of the bar.
Further, the temperature information before and after bar finish rolling is collected, including:
the method comprises the steps of utilizing a thermal imager to shoot a temperature field for bars before finish rolling, carrying out temperature data acquisition, and carrying out regional editing and positioning on the temperature field on the formed temperature field according to actual conditions of conventional rolling and splitting rolling, thereby forming multi-path data output, so that accurate temperature control of a water cooler on each bar subjected to conventional rolling and splitting rolling is realized through a flow-temperature cooling model.
Furthermore, the thermal imager has two modes for collecting the temperature field data information: one is line scanning and the other is area scanning.
For the cutting and rolling of the bars or the steel bars, the bouncing and the high-speed movement of the bars and the simultaneous transmission of a plurality of bars are difficult to acquire temperature signals. An infrared thermal imager, particularly an online infrared thermal imager is adopted to firstly carry out real-time temperature acquisition on the rolled and cooled bar, and the online infrared thermal imager with the resolution of 640x480 or 320x240 is selected according to the variety, specification and temperature requirements. Accurate and stable acquisition of temperature field data is achieved by focusing, automatic image capture, horizontality and span, analyzing the infrared video frame by frame through software at a remote location, and selecting an optional 2-fold or 4-fold additional lens for different applications.
Two methods are adopted in the aspect of outputting the temperature field data collected by the thermal imaging camera, wherein one method is line scanning, and the other method is area scanning. The linear scanning is to cut the bar in the rolling process by drawing a straight line in a bar temperature field, so that the temperature signal data of the bar and the temperature data between gaps are collected and output at the same time, then the peak value of a temperature curve is collected and processed through a background model, the position of each peak value is calibrated, and then the position is output together with corresponding data of each path, and the valve opening of each bar water cooler is controlled by combining a cooling model. The method comprises the steps of area scanning, firstly establishing data acquisition modes of a plurality of bars such as a single bar, 2 bars, 3 bars, 4 bars and the like, corresponding to a plurality of specific data in each mode, carrying out temperature acquisition and output on areas where the bars are located in a temperature field, carrying out automatic zoning acquisition on a production site according to a segmentation specification, defaulting the acquisition sequence, and using the output area data as a basis for controlling a water cooling model and the opening degree of a valve.
Further, a one-way air water cut-off cooler with the length of 1m-2m is adopted for pre-water treatment before the bar is finish rolled, so that the surface temperature of the bar is cooled to a target temperature, and the temperature difference between the core surface of the bar is smaller than 30 ℃; the temperature of the bar before finish rolling after pre-water treatment is controlled to be 70-100 ℃ higher than the temperature of Ar 1.
In controlling the cooling strength before finish rolling, the cooling to the target temperature must be ensured, and the temperature difference between the core and the surface of the bar material cannot be too large. Cooling to a target temperature, namely, a controlled cooling process before bar finish rolling needs to ensure that the finish rolling is within a two-phase region range, so that the finish rolling can generate the effect of deformation strengthening phase change, which is based on the difference of material components, according to a large amount of experiments, the invention concludes that the temperature of above 70-100 ℃ of the material Ar1 is the optimal temperature range for playing the effect of deformation strengthening phase change, and the temperature is too low, so that the deformation resistance of the finish rolling is easily increased, and simultaneously mixed crystals are easily generated; the temperature is too high, the deformation storage energy is reduced, and more phase change nucleation points cannot be generated.
For the cooling strength of the pre-through water, the temperature difference of the core surface of the rod must be ensured not to be too high, which has great relation with the form of the water cooler, and the embodiment adopts the one-way gas water-intercepting cooler, so that the forced cooling of the cooling water can be realized, and simultaneously, the gas interception in the water cooler can be ensured to seal the water, so that residual water on the surface is not caused, and a surface chilling tissue appears, which has certain requirements on the length of the water cooler before pre-finish rolling; meanwhile, the temperature difference of the core surface is too large, a steel plastic deformation area is easily generated on the surface in the rolling process, coarse grains are generated on the surface, and the surface deformation storage is insufficient, so that the threshold value of the temperature difference of the core surface of 30 ℃ is worked out by combining the critical occurrence condition of dynamic recrystallization of the material on the premise of utilizing DEFORM software for calculation.
Further, after the bar is finish rolled, a water cooler group is adopted for water passing treatment, and after the water passing treatment, the temperature of the bar on a cooling bed is maintained to be 40-70 ℃ below the Ar1 temperature;
the water cooler group consists of 6-8 one-way air intercepting water coolers which are connected in front and back and is used for realizing sectional cooling of the bar;
the length of each one-way air intercepting water cooler is 2m, and each one-way air intercepting water cooler can be cooled to 40-50 ℃.
6-8 one-way gas intercepting water coolers in the water cooler group can be independently controlled to be opened and closed, the working states of any two one-way gas intercepting water coolers are not affected with each other, and the temperature drop generated by each one-way gas intercepting water cooler is smaller than a preset temperature drop threshold value so as to meet the technical requirement of rod material water penetration.
The controlled cooling after the finish rolling requires a sufficient cooling length and combination. The cooling length must guarantee enough cooling strength after rolling, thereby guaranteeing that the rolled material is rapidly cooled to the temperature below the equilibrium phase change point after rolling, generating a certain supercooling degree on the material, determining the nucleation rate of the material by the supercooling degree, and finally generating the effect of refining grains. The combination mode is that the water coolers are flexibly controlled in layout, the new standard requires that the surface of the bar cannot generate a super-cooled structure, wherein no enough temperature recovery section is generated on the arrangement of the water coolers after rolling, and a quenching phenomenon is generated on the surface, the water cooler group of the embodiment adopts 6-8 one-way air water intercepting coolers, the water coolers can be freely combined, and according to the group distance of various specifications, the water coolers can be simultaneously opened with numbers 1, 3, 5 and 7, or simultaneously opened with numbers 2, 4, 6 and 8, … …, or simultaneously opened with numbers 1,2 and 3, or simultaneously opened with numbers 2,3 and 4, … …, in principle, a plurality of combination modes are provided, but in order to be suitable for the bar water passing process, the temperature drop of a single water cooler must be ensured not to be too large (namely, the temperature drop generated by each one-way air water intercepting cooler is smaller than a preset temperature drop threshold), otherwise, a quenched structure is generated in the cooling process, the relationship between the cooling rate after rolling and the structure performance is shown in table 1, and table 1 shows the transformation characteristics and the structure performance of the HRB400 steel under different cooling rates by taking the HRB400 steel as an example. The length of the single one-way air intercepting water cooler provided by the embodiment is 2m, the one-way air intercepting water cooler is also the optimal length calculated by fluent software, cooling and air intercepting can be arranged, the distance can be saved in space, and convenience is provided for arrangement of a post-rolling cooling control water cooler.
TABLE 1
Because the section of the bar is round in the water cooling stage, the section temperature of the bar can be calculated by using a finite difference method. And establishing a difference equation of the cylindrical coordinate system by using a thermal equilibrium method. When a difference equation of a one-dimensional cylindrical coordinate system is established by a thermal balance method, according to energy balance, the sum of heat flowing into a node i from a node i-1 and heat flowing into the node i from a node i + l increases the internal energy of the node i, and display difference is adopted.
Finishing to obtain:
t0 n+1＝4F0t1 n+(1-4F0)t0 n(1)
and (3) setting the boundary condition as a third boundary condition, namely convection and radiation, setting the total heat exchange coefficient as h and the number of outer boundary nodes as s, and writing a difference formula according to the law of energy conservation:
in the formula:
a temperature value, DEG C, representing the variation of each node i of the bar over time tau (i is 0,1, 2,3, …, s-1; n is 0,1, 2, …); f0Represents a flow rate value;
Δ τ represents the time interval, s; ρ represents the density of the bar, kg/m 3; c. CpRepresents the specific heat, J/(kg k); k represents the heat conductivity coefficient of the bar, w/(mk); .
Meanwhile, a model diagram of the regulating relation between Q (flow rate change value) and T (temperature) is calculated by using DEFORM finite element simulation, and is shown in FIG. 2.
According to the statistics of industrial production data, before the temperature closed-loop system is put into use, the maximum fluctuation value of the actual finish rolling inlet temperature is +/-25 ℃, and the maximum fluctuation value of the cooling bed inlet temperature is +/-18 ℃. According to the relationship of Q (flow variation value) -T (temperature) calculated in the figure 2, the maximum flow rate which needs to be regulated and controlled at the inlet of the water cooler can be calculated. According to the set flow, the pneumatic regulating valve is automatically regulated by using a PID algorithm, the flow, the pressure and the valve position value of the pneumatic regulating valve of cooling water in production are recorded, the process value of the cooling water flow is corrected by the pressure of the cooling water, so that the corrected value of the cooling water flow and the valve position corresponding value of the pneumatic regulating valve are obtained, and when closed-loop regulation is performed, the flow setting is corrected by adopting the following formula:
QSet＝Qt+aQ1+bQ2+cQ3+dQ4+eQ5+fQ6+gQ7+h (3)
in the formula, QsetIndicating the flow set point, Q1～Q7Respectively corresponding to flow values under the influence factors of rolling speed, temperature before cooling, current cooling water flow, cooling water pressure, cooling water temperature, bar diameter and cooling speed; a-h are respectively corresponding to the correction coefficients of the control system. And when the low flow rate regulation model is less than 15% of the pneumatic regulating valve, establishing a corresponding relation model of the flow rate and the valve opening, and performing weighting processing by recording the latest billet production data to self-learn and correct the regulation relation model of the flow rate and the temperature.
Further, the control process method further comprises the following steps:
and simulating the core surface temperature curve of the rod in the whole rolling and water cooling process by using DEFORM software, and reasonably determining the layout of the water cooler by combining with the phase change continuous transition CCT curve of the material.
And (3) predicting the core surface temperature of the bar in the rolling, water cooling and air cooling processes by using DEFORM computer software, and reasonably designing the layout of the water cooler by combining with a material phase change continuous transition curve (CCT). The purpose of analyzing the CCT curve is to obtain a mathematical expression form of the CCT curve, which requires a uniform expression to be used as much as possible, and curve fitting can achieve the purpose. The polynomial fitting has the characteristic of simple form, and the representation form of the CCT curve can be expressed by a polynomial. Therefore, a least square method is selected for polynomial fitting in the design process.
In general, given that n pairs of data (x, y) (i ═ 1,2,3 …, n), a polynomial of degree m (m is smaller than n-1) is now used as shown in the following equation. The starting point and the ending point of the phase change between different cold speeds of the phase change satisfy the polynomial relation, namely:
T＝av4+bv3+cv2+dv+e (4)
wherein a, b, c, d and e are regression constants, T is temperature, and v is cooling rate.
Fitting N pairs of hands with the above formula, where m +1 coefficients ai(i ═ 0,1, …, m) is to be determined. And (3) respectively substituting n pairs of data (x, y) into the formula to obtain a linear overdetermined equation set containing m +1 unknowns and n equations:
order to
Equation (7) can be expressed in matrix form:
equation (8) is solved using the least squares method,
the solution of equation (8) is the least squares solution of the linear over positive definite system of equations, i.e. the euclidean norm of the vector reaches a minimum value n. And taking the obtained numerical value of a as a coefficient corresponding to the original polynomial, wherein the obtained polynomial is obtained.
The specific application is as follows: the method of the embodiment is applied to the production of the 25mm steel bar 400E, and the lowest surface temperature of the steel bar at the inlet of the cooling bed can reach below 700 ℃; after the water cooler (which consists of a water inlet cavity, a circular seam, a turbulent pipe and an air intercepting device) is used on line, the steel bar does not generate wave bending; the water cooler is made of WCrMo wear-resistant steel at an inlet and an outlet, the quenching and tempering hardness is 62HRC, the turbulent tube is made of 42CrMo, and the quenching and tempering hardness is 58 HRC; implementation of
The average Mn content of HRB400E is 1.40-1.55%, and the Nb or VN alloy is not more than 0.01%. The requirements of the new national standard GB/T1499.2-2018 of the steel bar on various indexes of HRB400E steel bar are met.
The specific application is as follows: the method is applied to development of the steel bar for the building, a real-time closed-loop system with the bar material at the online constant target temperature is developed, and regulation and control can be completed in one steel rolling period. The temperature fluctuation of the finish rolling inlet and the cold bed inlet is respectively reduced from +/-25 ℃ and +/-18 ℃ to +/-10 ℃ and +/-8 ℃ (higher value), and the 400MPa grade yield strength fluctuation is reduced from 70MPa to 50 MPa. By developing real-time calculation of a full-flow full-section temperature curve of steel bar rolling and combining with models such as CCT/TTT, recrystallization and the like, forecasting of tissue types, phase proportions and the like of different positions of a core surface is realized, and the requirements of new national standards are met.
The concrete application is three: the method is applied to the production of the gear steel bar, and the water cooler is adopted to cool the bar through water before and after finish rolling, so that the temperature drop of the water cooler is controlled to be 60-80 ℃ before finish rolling, the temperature difference of a core surface is less than 30 ℃, and the temperature after water through treatment is controlled to be 70 ℃ above the temperature of Ar 1. By adopting low-temperature finish rolling, the storage energy of the structural deformation can be increased, the pearlite phase transformation of the deformed austenite after rolling is promoted, the uniformity of the radial temperature is ensured, and the structural uniformity is improved; after finish rolling, the temperature drop of a water cooler is controlled at 60 ℃, the temperature of an upper cooling bed is 785 ℃, and the temperature fluctuation is +/-10 ℃. By adopting a proper rolling and cooling control process, the difference between the rolled structure of the gear steel and the structures of the core part and the edge part is controlled, bainite and martensite are eliminated, the problem of lateral bending caused by structural stress after cold shearing is solved, and the yield of bars and the production efficiency of a steel rolling workshop are improved.
The rod water-cooling closed-loop control process method provided by the embodiment fully combines the low-cost production process of the steel bar and the product quality requirement, and realizes the technical service mode of 'equipment + process + variety development'; developing and designing a low-cost process production mode of 'limited controlled rolling + post-rolling multistage controlled cooling', and realizing accurate control of the temperature of the lowest point of cooling on the surface of the anti-seismic steel bar, so that the phase transformation starting point of bainite and martensite at the edge part is reduced, the grain size of ferrite at the center part of the anti-seismic steel bar is controlled to 7-9um in a refining way, no martensite is generated on the surface, and the optimal matching of high quality and low cost of the product is realized; the combined one-way air water intercepting cooler is designed to annularly reversely spray compressed air and vertically compress air to intercept water, so as to prevent the outlet of the water cooler from carrying water; through simulation of finite element software such as DEFORM and the like, proper rolling and cooling control process parameters are formulated, dislocation strengthening, fine grain strengthening and phase change strengthening mechanisms are coordinated and controlled, the yield ratio is improved, and the qualified rate of anti-seismic indexes is improved. By developing a water-cooling temperature closed-loop control system, the finish rolling and the temperature fluctuation of the inlet of a cooling bed can be obviously reduced, and the stability of the performance of the steel bar product poker is improved; the embodiment realizes the closed-loop control of multi-line splitting single temperature, thereby reducing the poor mechanical property of the multi-line; after the performance difference fluctuation is reduced, the reduction of the alloy consumption can be realized; the intelligent control level of the rolling line is improved, and the labor is reduced; by using the rod water-cooling closed-loop control process method, the production cost of the rod can be effectively reduced, and the cost of micro-alloy per ton of steel can be reduced by about 300 yuan/ton compared with that of a pure hot rolling process.
In addition, the temperature acquisition mode before finish rolling provided by the embodiment is also different from that of the conventional temperature measuring device. The conventional temperature measuring device is an infrared point type temperature measuring instrument, the number of the temperature measuring instruments needs to be increased and the positions of the temperature measuring instruments need to be changed for bars moving at a high speed and a plurality of bars after being cut, test data are screened, and particularly, temperature signals of the bars are difficult to detect if the outlet position of a finished product production line is bounced and fluctuated. In the embodiment, a thermal imager is adopted to shoot a temperature field for the bars before finish rolling, temperature data acquisition is carried out, and the temperature field is subjected to regional editing and positioning according to actual conditions of conventional rolling and splitting rolling in the formed temperature field, so that the temperature of the bars moving at high speed and a plurality of bars after splitting can be accurately acquired, and the accurate temperature control of the water cooler on each bar subjected to conventional rolling and splitting rolling can be realized through a flow-temperature cooling model at a later stage.
It should be noted that the rod water-cooling closed-loop control process method provided by the embodiment is also suitable for controlled cooling after rolling of the special steel rod, so as to solve the problems of cold shearing end cracking, steel bending and the like caused by large structure, large structure stress and poor plasticity due to the slow phase change process of the special steel rod. The grain size, net carbon and precipitate are controlled by a flexible cooling control process of water penetration section cooling after rolling, the product quality of special steel bar wires such as gear steel, bearing steel, non-adjusting steel and the like is improved by optimizing the cooling requirement before the bar is loaded on a cooling bed, and the smooth production is promoted.
The process method provided by the embodiment can realize the stability of the controlled rolling temperature and the controlled cooling process and reduce the alloy consumption of the bar by accurately controlling the pre-water-passing process and the finish rolling temperature before finish rolling, the water-passing process after rolling and the temperature of the cooling bed after water-passing; this embodiment adopts one or more one-way gas to cut off the cooler, and the realization is right the rod segmentation cooling has avoided the rod surface to organize unusually and the performance is undulant, has solved the rod surface water-cooling black circle tissue that leads to wearing water, heart table hardness subalternation problem, is favorable to improving steel factory production benefit.
Fig. 3 is a schematic structural diagram of a rod water-cooling closed-loop control system according to an embodiment of the present invention.
As shown in fig. 3, the rod water-cooling closed-loop control system according to this embodiment includes:
the production management subsystem 1, the coordination subsystem 2 and the rolling line water cooling control subsystem 3;
the production management subsystem 1 is used for performing unified management on the whole control system, and the production management subsystem 1 comprises: a server 11 and a first operator station 12;
the coordination subsystem 2 comprises: a communication master station and a second operator station 22;
the rolling line water cooling control subsystem 3 comprises: the communication slave station 31 is used for establishing communication connection with the communication master station;
the rolling line water-cooling control subsystem 3 is used for performing water-through cooling and temperature closed-loop control before and after bar finish rolling, and remotely transmitting production operation data to the server 11 through the communication slave station and the communication master station;
the rolling line water cooling control subsystem 3 further comprises: at least one cooling section;
each cooling section is provided with: the device comprises a water cooler, an infrared thermometer 32, a pressure gauge 33, a flow meter 34 and a pneumatic regulating valve 35, wherein the pneumatic regulating valve 35 is used for carrying out PID automatic regulation control on the water cooler.
Further, the infrared thermometer 32 is an infrared thermal imager, and is used for collecting the temperature of the rolled and cooled bar material in real time;
according to the requirements of variety specification size and temperature, the infrared thermal imager is an online thermal infrared imager with 640x480 or 320x240 resolution.
In practical use, the communication master station S7-300PLC21 is connected with the communication slave station 31 through a network, an optical fiber ring network is built through a plurality of other PLC stations 4, and the communication master station can access the server 11 on the production management subsystem 1 through the optical fiber ring network. The operation station on the production management subsystem 1 can also realize the accurate control of the pre-water-passing process before finish rolling, the finish rolling temperature, the water-passing process after finish rolling and the temperature of the cooling bed after water-passing according to the information of the temperature of the bar, the cooling water flow of the water cooler and the like through the communication master station and the communication slave station 31.
The working principle of the rolling line water-cooling control subsystem described in this embodiment is the same as that of the rod water-cooling closed-loop control process method provided in the above embodiment, and details are not repeated here.
It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.
It is to be noted that, in the description of the present invention, unless otherwise specified, "a plurality" means at least two, and "at least one" means one or more.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (7)
1. A rod water-cooling closed-loop control process method is characterized by comprising the following steps:
collecting temperature information before and after bar material finish rolling;
according to a through water cooling and temperature feedback closed-loop adjusting method, carrying out accurate rolling and cooling control on the conventional bar rolling and splitting rolling processes;
the temperature information before and after bar finish rolling is collected, and the temperature information comprises the following steps:
a thermal imager is utilized to shoot a temperature field of the bars before finish rolling, temperature data acquisition is carried out, and the temperature field is subjected to regional editing and positioning on the formed temperature field according to actual conditions of conventional rolling and splitting rolling, so that multi-path data output is formed, and accurate temperature control of the water cooler on each bar subjected to conventional rolling and splitting rolling is realized through a flow-temperature cooling model;
before the bar is finish rolled, a one-way air water intercepting cooler with the length of 1m-2m is adopted for pre-water passing treatment so as to cool the surface temperature of the bar to a target temperature and ensure that the temperature difference between the core surface of the bar is less than 30 ℃;
the temperature of the bar before finish rolling after pre-water treatment is controlled to be 70-100 ℃ higher than the temperature of Ar 1.
2. The process of claim 1, wherein the thermal imager collects temperature field data information in two ways: one is line scanning and the other is area scanning.
3. The process method according to claim 1, wherein the bar is subjected to water penetration treatment by a water cooler group after finish rolling, and the temperature of the upper cooling bed of the bar after the water penetration treatment is maintained within the range of 40 ℃ to 70 ℃ below the Ar1 temperature;
the water cooler group consists of 6-8 one-way air intercepting water coolers which are connected in front and back and is used for realizing sectional cooling of the bar;
the length of each one-way air intercepting water cooler is 2m, and each one-way air intercepting water cooler can be cooled to 40-50 ℃.
4. The process method as claimed in claim 3, wherein 6 to 8 one-way air intercepting water coolers in the water cooler group can be independently controlled to be opened and closed, the working states of any two one-way air intercepting water coolers are not affected with each other, and the temperature drop generated by each one-way air intercepting water cooler is smaller than a preset temperature drop threshold value so as to meet the bar water passing process requirement.
5. The process of claim 1, further comprising:
and simulating the core surface temperature curve of the rod in the whole rolling and water cooling process by using DEFORM software, and determining the layout of the water cooler by combining a material phase change continuous transition CCT curve.
6. A rod water-cooling closed-loop control system is characterized by comprising:
the production management subsystem, the coordination subsystem and the rolling line water cooling control subsystem;
the production management subsystem is used for carrying out unified management on the whole control system, and comprises: a server and a first operator station;
the coordination subsystem includes: the communication master station and the second operation station;
the rolling line water cooling control subsystem comprises: the communication slave station is used for establishing communication connection with the communication master station;
the rolling line water-cooling control subsystem is used for carrying out water-through cooling and temperature closed-loop control on the bar before and after finish rolling, realizing the process method of any one of claims 1 to 5, and remotely transmitting production operation data to the server through the communication slave station and the communication master station;
the rolling line water cooling control subsystem further comprises: at least one cooling section;
each cooling section is provided with: the device comprises a water cooler, an infrared thermometer, a pressure gauge, a flow meter and a pneumatic regulating valve, wherein the pneumatic regulating valve is used for carrying out PID automatic regulation control on the water cooler.
7. The system according to claim 6, wherein the infrared thermometer is an infrared thermal imager for real-time temperature acquisition of the rolled and cooled bar material;
according to the requirements of variety specification size and temperature, the infrared thermal imager is an online infrared thermal imager with 640x480 or 320x240 resolution.
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| CN110479776B (en) * | 2019-08-21 | 2020-11-27 | 中冶华天工程技术有限公司 | Closed-loop cooling control system and control method for rolled hot-rolled rod and wire |
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| CN112090967B (en) * | 2020-08-28 | 2022-03-18 | 中冶华天工程技术有限公司 | Through water cooling control method and system for long material rolling |
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| CN112329089B (en) * | 2020-09-29 | 2022-08-09 | 中冶华天工程技术有限公司 | Hot rolling rod wire rod full-process temperature field calculation system based on rolling program table |
| CN112496054B (en) * | 2020-11-26 | 2022-08-05 | 南京高精工程设备有限公司 | Closed-loop cooling control system and control method for hot-rolled rod and wire after rolling |
| CN113591246B (en) * | 2021-08-09 | 2023-06-23 | 中国计量大学 | Automatic die casting process optimization method based on DQN |
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