CN110805096A - Variable-frequency water supply control method for heat treatment of metal plate strip - Google Patents
Variable-frequency water supply control method for heat treatment of metal plate strip Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 184
- 238000010438 heat treatment Methods 0.000 title claims abstract description 78
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 55
- 239000002184 metal Substances 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000001816 cooling Methods 0.000 claims abstract description 140
- 238000006243 chemical reaction Methods 0.000 claims abstract description 35
- 230000001105 regulatory effect Effects 0.000 claims abstract description 35
- 230000008569 process Effects 0.000 claims abstract description 17
- 230000001276 controlling effect Effects 0.000 claims abstract description 6
- 230000009467 reduction Effects 0.000 claims abstract description 5
- 238000001595 flow curve Methods 0.000 claims description 12
- 230000008859 change Effects 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 239000000498 cooling water Substances 0.000 abstract description 5
- 238000010791 quenching Methods 0.000 description 6
- 230000000171 quenching effect Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 3
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B1/00—Methods or layout of installations for water supply
- E03B1/02—Methods or layout of installations for water supply for public or like main supply for industrial use
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- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B11/00—Arrangements or adaptations of tanks for water supply
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- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B7/00—Water main or service pipe systems
- E03B7/07—Arrangement of devices, e.g. filters, flow controls, measuring devices, siphons or valves, in the pipe systems
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- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
- E03B7/00—Water main or service pipe systems
- E03B7/07—Arrangement of devices, e.g. filters, flow controls, measuring devices, siphons or valves, in the pipe systems
- E03B7/075—Arrangement of devices for control of pressure or flow rate
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Abstract
The invention belongs to the field of heat treatment of metal plates and strips, and relates to a frequency conversion water supply control method for heat treatment of metal plates and strips. The method comprises the following steps of automatically calibrating a corresponding relation curve of the opening degree and the flow of a flow regulating valve in advance under a first condition, rapidly and accurately regulating the water supply pressure and the flow of a variable-frequency water supply system under a second condition by adopting a pressure double closed-loop control mode, accurately regulating and controlling the water flow of each nozzle of a cooling heat treatment system according to the thickness of a metal plate strip by adopting a flow closed-loop control mode under a third condition, and automatically controlling a frequency reduction time sequence of the variable-frequency water supply system and a nozzle closing time sequence of the cooling heat treatment system to realize constant-pressure stable water supply under a fourth. The invention meets the requirements of complex heat treatment process of various metal plates and strips on accurate and rapid control of cooling water quantity and water pressure, saves water and energy, has high automation degree, and realizes high flatness, high uniformity and high efficiency heat treatment of the metal plates and strips.
Description
Technical Field
The invention belongs to the field of heat treatment of metal plates and strips, and relates to a frequency conversion water supply control method for heat treatment of metal plates and strips.
Background
The heat treatment is a key process for improving the comprehensive performance of the metal plate strip, and particularly has obvious effects on improving the toughness, corrosion resistance, high-temperature performance, fatigue performance, processability and the like of the metal plate strip. The metal plate strips subjected to heat treatment are various (such as plain carbon steel, stainless steel, aluminum alloy, titanium alloy, high-temperature alloy and the like), the specification span is large (the thickness is 2-300 mm, the width is 800-5000 mm), and the heat treatment process is complex (such as normalizing, tempering, solid solution, quenching, controlled cooling, weak water cooling and the like).
The cooling is an important heat treatment process link of the metal plate strip, and different cooling paths are designed and controlled, so that the microstructure of the metal plate strip can be obviously improved, and more excellent performance can be obtained. In general, water or aqueous solution is used as a cooling medium in the cooling heat treatment of the metal plate strip, and the characteristics of easy acquisition of water, easy treatment, stable performance and high cost performance are utilized to realize different cooling systems and meet the requirements of different heat treatment processes. At present, the heat treatment of metal plate and strip materials develops towards the direction of refinement, complication, high efficiency, low energy consumption and the like, and higher requirements are put forward on the functions of a water supply system, the accurate control and the quick response of water supply parameters, a scientific and reasonable water supply strategy, an accurate and reliable automatic water supply-water regulation system and the like. The existing metal plate and strip heat treatment cooling water supply system has the practical problems of low precision, long adjusting time, high water consumption/energy consumption, low automation degree and the like and needs to be solved urgently.
In the existing patent, chinese patent application (publication No. CN208501798U) discloses a multifunctional variable frequency water supply system, which comprises a water storage tower, a variable frequency pressurizing module, a frequency converter, a controller, a pressure stabilizing module, a first check valve, a water pressure sensor and a flow sensor, and can realize automatic water quantity regulation according to the requirement and reduce the water hammer effect. The patent emphasizes the optimization of frequency conversion system equipment and the hardware upgrade of a control system, and is irrelevant to the innovation of the control method.
The Chinese patent application (publication No. CN104928463A) discloses a method for controlling a water supply system of a quenching machine of a hot-rolled steel plate heat treatment line, which meets the requirement of a simpler steel plate quenching process flow by manually setting variable-frequency water supply parameters. Because the manual operation steps are more, the automatic frequency conversion control functions of flow, pressure and the like are lacked, and the method has larger difference with the accurate, quick and stable frequency conversion water supply control and water and energy saving control method.
Chinese patent application (publication No. CN202030792U) discloses a water treatment device of a medium plate quenching line, which adopts a full frequency conversion water supply mode to adjust the water supply pressure of a system, thereby saving the engineering investment and the construction period. The innovation of the heavy water treatment equipment, the facility arrangement and the structure is irrelevant to the innovation of the variable-frequency water supply control method.
Disclosure of Invention
Aiming at the problems of poor regulation precision, low automation degree, long regulation time and outstanding water and power consumption of the existing metal plate and strip cooling and heat treatment water supply system, the invention aims to provide a variable-frequency water supply control method for metal plate and strip heat treatment, which can effectively improve the control precision and regulation speed of cooling process parameters in the metal plate and strip cooling and heat treatment process and realize high-efficiency, water-saving and energy-saving automatic heat treatment production.
The technical scheme of the invention is as follows:
a frequency conversion water supply control method for heat treatment of metal plate strips is realized by controlling a cooling heat treatment system, wherein the cooling heat treatment system comprises a high-pressure frequency conversion water supply system and a low-pressure frequency conversion water supply system; the high-pressure variable frequency pump of the high-pressure cooling area and the low-pressure variable frequency pump of the low-pressure cooling area control the pressure in the integral water supply pipeline through corresponding water pump motor frequency converters respectively; the water supply pipeline controls the water flow of each cooling nozzle in the high-pressure variable-frequency water supply system and the low-pressure variable-frequency water supply system through a flow regulating valve and a flowmeter; the control system is used for monitoring the pressure change of the whole system; the method comprises the following conditions:
in the first situation, when the cooling heat treatment system is in a non-working state, the high-pressure variable-frequency water supply system adjusts the working pressure of a high-pressure cooling area to 0.8-1.0 MPa, and the low-pressure variable-frequency water supply system adjusts the working pressure of a low-pressure cooling area to 0.4-0.5 MPa; the opening degree of each flow regulating valve of the cooling nozzle water supply pipeline of the cooling heat treatment system is increased from 0% to 20-30 times to 100% in an increasing mode of 3.3% -5%, the opening degree of each flow regulating valve is controlled by the control system to be automatically increased, and the control system judges that the pressure deviation is +/-0.01 MPa and the flow deviation is +/-3-5 m when the opening degree of each flow regulating valve is increased to a new opening degree value3And when the flow value is within the/h range, automatically recording the flow value at the moment, drawing a flow curve by using a curve fitting method through the control system, and calculating the flow value corresponding to the opening degree in the adjacent opening degree test value range by adopting an interpolation method.
In the second situation, when the cooling heat treatment system is in a working state, the control system determines the number of the high-pressure variable-frequency pumps and the low-pressure variable-frequency pumps to be increased and sends an increasing signal 80-100 s before the metal plate strip begins to be cooled, and the high-pressure variable-frequency water supply system and the low-pressure variable-frequency water supply system respectively increase the water supply pressure to 0.8-1.0 MPa of working pressure of a high-pressure cooling area and 0.4-0.5 MPa of working pressure of a low-pressure cooling area within 10-20 s; if the control system judges that the frequency increasing number of the high-pressure frequency conversion pumps or the low-pressure frequency conversion pumps is not less than 2, determining that the frequency increasing of the high-pressure water supply pumps or the low-pressure water supply pumps is alternatively increased, wherein the frequency increasing amplitude is 1Hz, forming pressure closed-loop control by utilizing a high-pressure frequency conversion pump outlet pressure sensor or a low-pressure frequency conversion pump outlet pressure sensor and a water pump motor frequency converter, and calculating the target control pressure which is the pressure loss of a water supply pipeline and the working pressure of a high-pressure cooling area or the working pressure of a low-pressure;
when the cooling heat treatment system is in a working state, after the high-pressure frequency conversion water supply system and the low-pressure frequency conversion water supply system provide constant working pressure, a control system of the cooling heat treatment system opens a water supply pipeline flow regulating valve and controls the opening degree of the flow regulating valve according to a cooling rule and a flow curve, the water flow of the water supply pipeline is roughly regulated, a pressure closed loop control is formed by a pressure sensor of a high-pressure cooling area or a low-pressure cooling area of the cooling heat treatment system and a water pump motor frequency converter, the working pressure is maintained, and after the flow regulating valve is opened for 5-10 s, the flow closed loop control is formed by the water supply pipeline flow regulating valve and a water supply pipeline;
in the fourth situation, when the tail part of the metal plate strip leaves the high-pressure cooling area of the cooling heat treatment system, the control system sends a frequency reduction signal of the high-pressure frequency conversion water supply system, a pressure closed-loop control is formed by using a high-pressure frequency conversion pump outlet pressure sensor and a water pump motor frequency converter, the target control pressure is the pressure loss of a calculated water supply pipeline plus the non-working pressure of the high-pressure cooling area of the cooling heat treatment system, and the cooling heat treatment system sequentially closes the opened cooling nozzles of the high-pressure cooling area after the high-pressure frequency conversion water supply system controls the water pressure to be reduced; after the tail part of the metal plate strip leaves a group of opened cooling nozzles in a low-pressure cooling area of a cooling heat treatment system, the group of cooling nozzles are closed until the last group of opened cooling nozzles in the low-pressure cooling area are closed, in the process, a pressure closed-loop control is formed by a pressure sensor of the low-pressure cooling area of the cooling heat treatment system and a frequency converter of a water pump motor, the working pressure of the low-pressure cooling area is maintained, after the tail part of the metal plate strip leaves the last group of opened cooling nozzles in the low-pressure cooling area, a pressure closed-loop control is formed by a pressure sensor of an outlet of the low-pressure frequency converter and the frequency converter of the water pump motor, and the target control pressure is calculated as water supply pipeline.
Further, in case three, the fine adjustment of the water flow rate of the water supply line is performed as follows: the water flow regulating precision of each cooling nozzle corresponding to the water supply pipeline is divided according to the thickness of the metal plate strip: the thickness of the metal plate strip is less than or equal to 8mm, and the water flow regulation precision is +/-3-4 m3H, the thickness of the metal plate strip is more than 8mm and less than or equal to 15mm, and the water flow regulation precision is +/-4-6 m3H, the thickness of the metal plate strip is more than 15mm and less than or equal to 30mm, and the water flow regulation precision is +/-6-8 m3H, the thickness of the metal plate strip is more than 30mm, and the water flow regulation precision is +/-8-10 m3/h。
The invention has the advantages and beneficial effects that:
1. before the cooling heat treatment system is not put into use, the flow curve is calibrated in advance, the quick coarse adjustment of the water quantity of the variable-frequency water supply system is realized, and the water quantity adjusting time is shortened by nearly 30 percent.
2. When the cooling heat treatment system is not put into use, the variable frequency water supply system is in a low-frequency running state, so that water and electricity are saved.
3. When the cooling heat treatment system is put into use, the frequency conversion water supply system firstly boosts and pre-adjusts the water supply pressure, then the flow regulating valve opens the nozzle according to the flow curve, and the flow regulation adopts two steps of coarse regulation and fine regulation, thereby improving the regulation precision of water quantity and water pressure and shortening the regulation time.
4. The cooling nozzle of the cooling heat treatment system divides the water quantity adjusting precision according to the thickness of the metal plate strip, and the water quantity adjusting time is further shortened on the premise of ensuring the smooth implementation of the heat treatment process.
5. The control mode and the frequency reduction time of the high-pressure variable-frequency water supply system and the low-pressure variable-frequency water supply system are determined according to the tail position of the metal plate strip, the cooling water spraying time is shortened to about 1/2, water and energy are saved, and the phenomenon of 'water hammer' of a pipeline is effectively improved.
Drawings
FIG. 1 is a schematic view of a variable frequency water supply control method for heat treatment of metal plate and strip in the invention.
In the figure: 1 cooling the heat treatment system; 2, a high-pressure variable-frequency water supply system; 3, a low-pressure variable-frequency water supply system; 4 a high-pressure cooling area; 5 a low pressure cooling zone; 6 cooling the nozzle; 7, controlling the system; 8 sheet metal strip; 9, a high-pressure variable frequency pump; 10 low-voltage variable frequency pump; 11 a pressure sensor; 12 water pump motor frequency converter; 13 a water supply line; 14 flow regulating valve; 15 a flow meter; 16 roller table.
Detailed Description
The following describes a variable-frequency water supply control method for heat treatment of metal plate and strip with reference to the attached drawing 1.
Example one
In the present example, a specific embodiment of a frequency-variable water supply control method for heat treatment of a metal plate and strip is described by taking a quenching heat treatment of a metal plate and strip with a thickness of 20mm, a width of 2500mm and a length of 13m as an example:
as shown in fig. 1, when the cooling heat treatment system 1 is in a non-operating state and a non-flow curve calibration state, the high-pressure variable-frequency water supply system 2 maintains a non-operating pressure of the high-pressure cooling area 4 of 0.4MPa, the low-pressure variable-frequency water supply system 3 maintains a non-operating pressure of the low-pressure cooling area 5 of 0.2MPa, and the supplied cooling water is used for cooling the cooling nozzle 6;
the control system 7 of the cooling heat treatment system 1 determines 2 high-pressure variable frequency pumps 9 and 2 low-pressure variable frequency pumps 10 which need frequency boosting according to cooling regulations 100s before a metal plate strip 8 starts to be cooled and sends frequency boosting signals, the high-pressure variable frequency water supply system 2 raises the water supply pressure to 4 working pressures of a 0.8MPa high-pressure cooling area within 20s, the low-pressure variable frequency water supply system 3 raises the water supply pressure to 5 working pressures of a 0.4MPa low-pressure cooling area within 20s, the 2 high-pressure water supply pumps 9 and the 2 low-pressure water supply pumps 10 which raise the frequency are determined to alternately raise the frequency respectively, the frequency raising amplitude is 1Hz, pressure closed-loop control is formed by using a pressure sensor 11 at the outlet of the high-pressure variable frequency pump 9 or the low-pressure variable frequency pump 10 and a water pump motor frequency converter 12, the target control pressure of the high-pressure variable frequency water supply system 2 is 0.86MPa +/-0.01 MPa, and the target.
After the target control pressure is reached, a control system 7 of the cooling heat treatment system 1 opens a water supply pipeline 13 flow regulating valve 14 and controls the opening degree of the flow regulating valve 14 according to a cooling rule and a flow curve, the water flow of the water supply pipeline 13 is roughly regulated, a pressure sensor 11 of a high-pressure cooling area 4 or a low-pressure cooling area 5 of the cooling heat treatment system 1 and a water pump motor frequency converter 12 form pressure closed-loop control, the working pressure is maintained, after the flow regulating valve 14 is opened for 5-10 s, the flow closed-loop control is formed by the water supply pipeline 13 flow regulating valve 14 and a water supply pipeline 13 flowmeter 15, the water flow of the water supply pipeline 13 is finely regulated, and the water flow regulating precision of3In the flow fine adjustment process, the high-pressure variable-frequency water supply system 2 and the low-pressure variable-frequency water supply system 3 provide cooling water with constant working pressure; after the water flow and the pressure of the cooling nozzles 6 which are respectively opened in the high-pressure cooling area 4 and the low-pressure cooling area 5 meet the requirements of the heat treatment process, the metal plate strip 8 is transported by the roller way 16 to sequentially enter the high-pressure cooling area 4 and the low-pressure cooling area 5 of the cooling heat treatment system 1, and the quenching heat treatment process is completed; metalWhen the tail part of the plate and strip material 8 leaves the high-pressure cooling area 4 of the cooling heat treatment system 1, the control system 7 sends a frequency reduction signal of the high-pressure frequency conversion water supply system 2, pressure closed-loop control is formed by the pressure sensor 11 at the outlet of the high-pressure frequency conversion pump 9 and the frequency converter 12 of the water pump motor, the target control pressure is 0.44MPa +/-0.01 MPa, and after the target control pressure is reached, the cooling heat treatment system 1 sequentially closes the cooling nozzles 6 of the opened high-pressure cooling area 4.
After the tail part of the metal plate strip 8 leaves a certain group of opened cooling nozzles 6 of the low-pressure cooling area 5 of the cooling heat treatment system 1, the group of cooling nozzles 6 are closed until the last group of opened cooling nozzles 6 of the low-pressure cooling area 5 is closed, in the process, a pressure closed-loop control is formed by a pressure sensor 11 of the low-pressure cooling area 5 of the cooling heat treatment system 1 and a water pump motor frequency converter 12, the working pressure of the low-pressure cooling area 5 of 0.4MPa +/-0.01 MPa is maintained, after the tail part of the metal plate strip 8 leaves the opened cooling nozzles 6 of the last group of low-pressure cooling area 5, a pressure closed-loop control is formed by an outlet pressure sensor 11 of a low-pressure frequency conversion pump 10 and the water pump motor frequency converter 12, and the target control pressure is 0.. And finally, finishing the implementation of the variable-frequency water supply control method for the heat treatment of the metal plate strip.
Example two
This example illustrates a specific embodiment of a flow curve calibration method when a cooling heat treatment system is in a non-operating state:
as shown in fig. 1, before calibrating the flow curve, the high-pressure variable-frequency water supply system 2 and the low-pressure variable-frequency water supply system 3 respectively select 2 high-pressure variable- frequency pumps 9 and 2 low-pressure variable-frequency pumps 10 to increase the frequency, the high-pressure variable-frequency water supply system 2 increases the water supply pressure to 0.8MPa high-pressure cooling area 4 working pressure, the low-pressure variable-frequency water supply system 3 increases the water supply pressure to 0.4MPa low-pressure cooling area 5 working pressure, the high-pressure water supply pump 9 or the low-pressure water supply pump 10 which is selected to increase the frequency alternately with the frequency increasing amplitude of 1Hz is selected, a pressure closed-loop control is formed by using a pressure sensor 11 at the outlet of the high-pressure variable-frequency pump 9 or the low-pressure variable-frequency pump 10 and a water pump motor frequency converter 12, and the target control pressure is; after the water supply pressure meets the calibration requirement of a flow curve of +/-0.1 MPa, cooling each water supply of the heat treatment system 1The opening degree of the flow regulating valve 14 of the pipeline 13 is increased from 0% to 100% in 20 times by 5%, the opening degree of the flow regulating valve 14 is controlled by the control system 7 to be automatically increased, and the control system 7 judges that the pressure deviation is +/-0.01 MPa and the flow deviation is +/-5 m when the opening degree of the flow regulating valve 14 is increased to a new opening degree value every time3And when the flow value is within the range of/h, automatically recording the flow value at the moment as the flow value corresponding to the opening degree at the moment, recording 20 flow values for each cooling nozzle 6, drawing a flow curve by the control system 7 by using a curve fitting method, and calculating the flow value corresponding to the opening degree in the range of the flow value tested by the adjacent opening degree by adopting an interpolation method.
The result shows that the invention solves the problem of rapid and accurate adjustment of the water flow and the pressure of the cooling nozzle of different specifications and varieties of metal plates and strips under the conditions of different heat treatment process systems, realizes automatic production, meets the aims of improving the production efficiency, saving water and energy, and obviously improves the control precision of the heat treatment process of the metal plates and strips.
Claims (2)
1. A frequency conversion water supply control method for heat treatment of metal plate strips is realized by controlling a cooling heat treatment system (1), wherein the cooling heat treatment system (1) comprises a high-pressure frequency conversion water supply system (2) and a low-pressure frequency conversion water supply system (3); the high-pressure variable frequency pump (9) of the high-pressure cooling area (4) and the low-pressure variable frequency pump (10) of the low-pressure cooling area (5) respectively control the pressure in the integral water supply pipeline (13) through corresponding water pump motor frequency converters; the water supply pipeline (13) controls the water flow of each cooling nozzle in the high-pressure variable-frequency water supply system (2) and the low-pressure variable-frequency water supply system (3) through a flow regulating valve and a flowmeter; the control system (7) is used for monitoring the pressure change of the whole system; characterized in that the method comprises the following conditions:
in the first situation, when the cooling heat treatment system is in a non-working state, the high-pressure variable-frequency water supply system adjusts the working pressure of a high-pressure cooling area to 0.8-1.0 MPa, and the low-pressure variable-frequency water supply system adjusts the working pressure of a low-pressure cooling area to 0.4-0.5 MPa; the opening degree of a flow regulating valve of each cooling nozzle water supply pipeline of the cooling heat treatment system is increased from 0 percent to 20 to 30 times to 100 percent in an increasing range of 3.3 to 5 percent, and the flow is controlled by a control systemThe opening degree of the regulating valve is automatically increased gradually, and when the opening degree of the flow regulating valve is increased gradually to a new opening degree value, the control system judges that the pressure deviation is +/-0.01 MPa and the flow deviation is +/-3-5 m3When the flow value is within the/h range, automatically recording the flow value at the moment, drawing a flow curve by using a curve fitting method through the control system, and calculating the flow value corresponding to the opening degree in the adjacent opening degree test value range by adopting an interpolation method;
in the second situation, when the cooling heat treatment system is in a working state, the control system determines the number of the high-pressure variable-frequency pumps and the low-pressure variable-frequency pumps to be increased and sends an increasing signal 80-100 s before the metal plate strip begins to be cooled, and the high-pressure variable-frequency water supply system and the low-pressure variable-frequency water supply system respectively increase the water supply pressure to 0.8-1.0 MPa of working pressure of a high-pressure cooling area and 0.4-0.5 MPa of working pressure of a low-pressure cooling area within 10-20 s; if the control system judges that the frequency increasing number of the high-pressure frequency conversion pumps or the low-pressure frequency conversion pumps is not less than 2, determining that the frequency increasing of the high-pressure water supply pumps or the low-pressure water supply pumps is alternatively increased, wherein the frequency increasing amplitude is 1Hz, forming pressure closed-loop control by utilizing a high-pressure frequency conversion pump outlet pressure sensor or a low-pressure frequency conversion pump outlet pressure sensor and a water pump motor frequency converter, and calculating the target control pressure which is the pressure loss of a water supply pipeline and the working pressure of a high-pressure cooling area or the working pressure of a low-pressure;
when the cooling heat treatment system is in a working state, after the high-pressure frequency conversion water supply system and the low-pressure frequency conversion water supply system provide constant working pressure, a control system of the cooling heat treatment system opens a water supply pipeline flow regulating valve and controls the opening degree of the flow regulating valve according to a cooling rule and a flow curve, the water flow of the water supply pipeline is roughly regulated, a pressure closed loop control is formed by a pressure sensor of a high-pressure cooling area or a low-pressure cooling area of the cooling heat treatment system and a water pump motor frequency converter, the working pressure is maintained, and after the flow regulating valve is opened for 5-10 s, the flow closed loop control is formed by the water supply pipeline flow regulating valve and a water supply pipeline;
in the fourth situation, when the tail part of the metal plate strip leaves the high-pressure cooling area of the cooling heat treatment system, the control system sends a frequency reduction signal of the high-pressure frequency conversion water supply system, a pressure closed-loop control is formed by using a high-pressure frequency conversion pump outlet pressure sensor and a water pump motor frequency converter, the target control pressure is the pressure loss of a calculated water supply pipeline plus the non-working pressure of the high-pressure cooling area of the cooling heat treatment system, and the cooling heat treatment system sequentially closes the opened cooling nozzles of the high-pressure cooling area after the high-pressure frequency conversion water supply system controls the water pressure to be reduced; after the tail part of the metal plate strip leaves a group of opened cooling nozzles in a low-pressure cooling area of a cooling heat treatment system, the group of cooling nozzles are closed until the last group of opened cooling nozzles in the low-pressure cooling area are closed, in the process, a pressure closed-loop control is formed by a pressure sensor of the low-pressure cooling area of the cooling heat treatment system and a frequency converter of a water pump motor, the working pressure of the low-pressure cooling area is maintained, after the tail part of the metal plate strip leaves the last group of opened cooling nozzles in the low-pressure cooling area, a pressure closed-loop control is formed by a pressure sensor of an outlet of the low-pressure frequency converter and the frequency converter of the water pump motor, and the target control pressure is calculated as water supply pipeline.
2. The frequency conversion water supply control method for the heat treatment of the metal plate strip as claimed in claim 1, wherein in case three, the operation of finely adjusting the water flow rate of the water supply pipeline is as follows: the water flow regulating precision of each cooling nozzle corresponding to the water supply pipeline is divided according to the thickness of the metal plate strip: the thickness of the metal plate strip is less than or equal to 8mm, and the water flow regulation precision is +/-3-4 m3H, the thickness of the metal plate strip is more than 8mm and less than or equal to 15mm, and the water flow regulation precision is +/-4-6 m3H, the thickness of the metal plate strip is more than 15mm and less than or equal to 30mm, and the water flow regulation precision is +/-6-8 m3H, the thickness of the metal plate strip is more than 30mm, and the water flow regulation precision is +/-8-10 m3/h。
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Application publication date: 20200218 |