Method for reducing poor performance and metal consumption of head and tail of coiled screw

Abstract

The invention discloses a method for reducing the head and tail performance difference and metal consumption of a coiled screw. The method comprises the following steps that a steel signal of a pre-finish rolling first frame rolling mill is detected, a water tank water volume gradient decline mode is started, the water volume decline time interval and decline amplitude are set, a steel throwing signal of the pre-finish rolling first frame is detected, the water volume is recovered to 100%, and circulation is conducted; and the air cooling control system receives a finished product steel feeding signal, the frequency of the fan is automatically increased to the highest working frequency after set time delay, and after the head of the coil reaches the strong blowing position, the frequency of the fan is reduced to the normal frequency after preset strong blowing time. According to the method, a steel signal of a first rolling mill in pre-finish rolling is taken as a trigger condition, a water volume decline mode is adopted for water tank control, a decline time interval and a decline amplitude are set, a control mode of a fan is optimized, the fan is subjected to time delay and automatic frequency increasing operation after receiving a steel signal, and the frequency is reduced back to a normal frequency after a strong blowing duration written by a program; and head and tail performance differences of the coiled screws are reduced, and metal consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling, in particular to a method for reducing poor performance of coil heads and tails and metal consumption. Background Art

[0002] The rolling process of the double-high-speed wire is a head-off rolling process after the rough rolling. Since the length of the steel-dividing roller is approximately 51m, the steel-dividing roller takes approximately 60-90 seconds to run on the steel-dividing roller, depending on the rolling speed. This results in a temperature difference of approximately 40°C between the head and tail of the steel when it enters the intermediate rolling mill. Measurements of the temperature difference at the intermediate rolling mill outlet also maintain it at around 30°C. This results in the steel-dividing roller having a high head temperature and a low tail temperature during the high-speed rolling process. Furthermore, to ensure stable rolling, high-speed wire rods are typically cooled with water at the head of the wire rod after rolling. This exacerbates the temperature difference between the head and tail of the finished product, resulting in a high head temperature and a low tail temperature, seriously affecting the stability of the coiled wire rod performance.

[0003] The ribbed surface of coils creates excessive resistance at the head when passing through water, leading to steel accumulation. Therefore, during the production of basic coils (especially small sizes), the head must be clamped by pinch rollers to create tension before water can be turned on to quickly reach the phase change range. Limited by the equipment installation conditions, the finished product rack is generally about 40 meters away from the pinch rollers. Therefore, the temperature of the finished coil head within a few dozen meters is generally several dozen degrees higher than that of the middle and tail parts. This temperature difference seriously affects the phase change of the finished coil, resulting in large performance deviations at the head and tail of the coil. Currently, the market has increasingly higher quality requirements for steel products, resulting in more and more quality disputes due to abnormal performance of coils. Completely shearing the uncooled section of the finished product will seriously affect the metal yield. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for reducing the poor performance of the head and tail of the coil and reducing the metal consumption.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for reducing the poor performance of the head and tail of the spiral shell and metal consumption, comprising the following steps:

[0006] When the steel signal of the first stand of the pre-finishing rolling mill is detected, the water volume gradient reduction mode of the water tank is started, the time interval and the reduction amplitude of the water volume are set, and the steel throwing signal of the first stand of the pre-finishing rolling mill is detected, the water volume is restored to 100%, and the cycle is repeated;

[0007] The air cooling control system receives the finished steel arrival signal, and the fan automatically increases the frequency to the highest operating frequency after a set delay. After the coil head reaches the strong blowing position, the fan returns to normal frequency after the preset strong blowing time.

[0008] As a further improvement of the present invention: the control method of the fan specifically includes:

[0009] Set the total frequency rise time required for the fan to rise from startup to the maximum operating frequency;

[0010] Calculate the theoretical time from the coil head to the inlet of each fan;

[0011] The start frequency increase time and the start frequency reduction time of the fan are set according to the total frequency increase time and the theoretical time.

[0012] As a further improvement of the present invention: the total frequency rise time is less than or equal to the difference between the theoretical time and the set delay.

[0013] As a further improvement of the present invention, the frequency increase process of the fan is controlled by a piecewise linear frequency increase mode, specifically including:

[0014] The first preset time required for the low frequency band to set the unit frequency up-conversion;

[0015] The second preset time required for the mid-frequency band to set the unit frequency up-conversion;

[0016] A third preset time required for the high frequency band to set the unit frequency up-conversion;

[0017] The first preset time, the second preset time and the third preset time decrease in sequence, and the interval length of the low frequency band and the interval length of the medium frequency band are both greater than the interval length of the high frequency band.

[0018] As a further improvement of the present invention: a full linear frequency increase mode is adopted, and the time required for unit frequency increase is set.

[0019] As a further improvement of the present invention: the frequency reduction process of the fan adopts a piecewise linear frequency reduction mode, including setting the time required for unit frequency reduction of the medium frequency band and the low frequency band respectively.

[0020] As a further improvement of the present invention: the water volume in the water tank is controlled by installing an electrically controlled diaphragm valve.

[0021] As a further improvement of the present invention: the decreasing time interval and the decreasing amplitude are fixed values.

[0022] As a further improvement of the present invention: the piecewise linear frequency up-conversion mode includes:

[0023] The unit frequency increase in the 0-20Hz band is 0.4-0.6s / Hz;

[0024] The unit frequency increase in the 20-40Hz band is 0.2-0.3s / Hz;

[0025] The unit frequency increase in the 40-50Hz frequency band is 0.1-0.15s / Hz.

[0026] As a further improvement of the present invention: the decreasing amplitude is 3%-5%, and the decreasing time interval is 10 seconds.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The water tank control of the present invention adopts a water volume decreasing mode, and designs a reasonable gradient decreasing time interval and decreasing amplitude to form a closed-loop control of steel signal triggering + water volume gradient decreasing + steel throwing recovery. At the same time, after the fan receives the incoming steel signal, it automatically increases the frequency after a set delay. When the coil head reaches the strong blowing position, it operates at the highest operating frequency for the set strong blowing time and then returns to the normal frequency, thereby solving the problem of precise control of the temperature of the coil head and tail, and solving the problems of large performance differences and high metal consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the water tank water volume reduction control of the present invention.

[0030] Figure 2 It is a flow chart of the fan frequency increase control process of the present invention. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0033] In order to solve the technical problems in the prior art, the present invention is further described with reference to the accompanying drawings and embodiments:

[0034] like Figures 1 to 2 As shown, the present invention discloses a method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption, comprising the following steps:

[0035] When the steel signal of the first stand of the pre-finishing rolling mill is detected, the water volume gradient reduction mode of the water tank is started, the time interval and the reduction amplitude of the water volume are set, and the steel throwing signal of the first stand of the pre-finishing rolling mill is detected, the water volume is restored to 100%, and the cycle repeats;

[0036] The air cooling control system receives the finished steel arrival signal, and the fan automatically increases the frequency to the highest operating frequency after a set delay. After the coil head reaches the strong blowing position, the fan returns to normal frequency after the preset strong blowing time.

[0037] The present invention optimizes the temperature difference between the head and tail of the rolled piece by designing a pre-water cooling gradient cooling mode after pre-finishing rolling, thereby reducing the performance difference and metal consumption of the coil. The core of this mode is to use the steel signal of the first rolling mill of pre-finishing rolling as the trigger condition, adopt a water volume reduction control method, and restore the initial water volume after throwing the steel to form a circulation control. At the same time, it optimizes and reduces the frequency rise time of the fan to improve the cooling intensity of the wire rod head. It realizes rapid cooling of high water volume at the head, gradually reduces the cooling amount at the tail, narrows the temperature difference between the head and tail, and automatically adjusts based on the rolling mill signal without manual intervention, which is suitable for high-speed continuous production. By designing a pre-water cooling gradient cooling mode after pre-finishing rolling and optimizing the control method of the fan, the temperature of the head of the rolled piece after the air cooling is reduced by about 30°C compared with the original temperature.

[0038] From simply improving the performance of the head to appropriately reducing the performance of the tail, the characteristics of the variable frequency fan are used to the maximum extent possible to achieve air cooling enhancement at different stages, and the connection between the high-speed zone signal and the air cooling line signal is simultaneously completed.

[0039] The first rolling mill (first stand) of the pre-finishing rolling mill group is equipped with a high-precision photoelectric sensor or pressure sensor to detect the signal of the rolled piece entering. This signal serves as the starting instruction of the entire pre-water cooling system to ensure that the cooling control is synchronized with the rolling rhythm.

[0040] The control logic of the water tank water reduction mode includes:

[0041] Initial state: The water tank is open to 100% (maximum water volume) to ensure rapid cooling of the head.

[0042] Decrease process: Set the decrease time interval and decrease amplitude. Adjust the decrease time or amplitude for different coil sizes (such as Φ8mm and Φ10mm). For example, the program sets a fixed time interval (such as 10 seconds), reduces the water volume by a certain amount every time, and sets the decrease amplitude to a fixed value (such as reducing the opening by 5% each time) to ensure that the cooling intensity decreases gradually.

[0043] When the first pre-finishing mill detects the tail of the workpiece leaving the mill (steel throw), a signal is sent to the control system. The water tank opening is immediately restored to 100% to prepare for cooling the head of the next workpiece. This ensures cycle control and adapts to the rhythm of continuous rolling production.

[0044] The water volume in the water tank is controlled by installing an electric control diaphragm valve. It is preferred that the electric control diaphragm valve with higher response accuracy is used to control the water volume in the water tank.

[0045] In some implementations, the fan control method specifically includes:

[0046] Set the total frequency rise time required for the fan to rise from startup to the maximum operating frequency;

[0047] Calculate the theoretical time from the coil head to the inlet of each fan;

[0048] The start frequency increase time and the start frequency reduction time of the fan are set according to the total frequency increase time and the theoretical time.

[0049] The steel signal from the pinch rolls of the rolling mill is connected to the air cooling control system, optimizing the connection between the air cooling line control program and the rolling mill control program. By repeatedly operating this control, the variable frequency fan achieves forced cooling of the uncooled section at the head, thereby reducing the temperature difference between the head, middle, and tail of the finished product. Ultimately, this reduces shearing at the head and tail of the coil while stabilizing performance, thereby improving the yield rate.

[0050] In some embodiments, the total frequency ramp-up time is less than or equal to the difference between the theoretical time and the set delay. Generally, the total frequency ramp-up time is equal to the difference between the theoretical time and the set delay. When the coil head reaches the fan inlet, the fan operating frequency has reached the maximum operating frequency.

[0051] In some implementations, the frequency increase process of the fan is controlled using a piecewise linear frequency increase mode, specifically including:

[0052] The first preset time required for the low frequency band to set the unit frequency up-conversion;

[0053] The second preset time required for the mid-frequency band to set the unit frequency up-conversion;

[0054] A third preset time required for the high frequency band to set the unit frequency up-conversion;

[0055] The first preset time, the second preset time and the third preset time decrease in sequence, and the interval length of the low frequency band and the interval length of the medium frequency band are both greater than the interval length of the high frequency band.

[0056] The fan frequency rise adopts a segmented acceleration method, which sets the total frequency rise time of the variable frequency fan. That is, the time required from the fan starting to the highest 50Hz (100%) is divided into the time required for unit frequency rise.

[0057] Furthermore, the piecewise linear up-conversion mode includes: the unit up-conversion of the 0-20Hz frequency band is 0.4-0.6s / Hz; the unit up-conversion of the 20-40Hz frequency band is 0.2-0.3s / Hz; and the unit up-conversion of the 40-50Hz frequency band is 0.1-0.15s / Hz.

[0058] In some implementations, the fan frequency increase control adopts a full linear frequency increase mode, and the time required for a unit frequency increase is set, that is, the duration required for the variable frequency fan to increase the frequency by 1 Hz.

[0059] In some implementations, the frequency reduction process of the fan adopts a piecewise linear frequency reduction mode, including setting the time required for unit frequency reduction in the middle frequency band and the low frequency band respectively.

[0060] The present invention designs a pre-water cooling gradient cooling mode after pre-finishing rolling, optimizes the control mode of the fan, takes the steel signal of the first rolling mill of pre-finishing rolling as the trigger condition, adopts the water volume reduction mode for water tank control, sets the reduction time interval, sets the reduction amplitude program to a fixed value, and the first rolling mill of pre-finishing rolling throws steel, and the water volume is restored to 100%, and the cycle repeats. Set the total frequency increase time of the variable frequency fan. That is, the time required from the start of the fan to the highest 50Hz (100%) is divided into the time required for unit frequency increase. When the speed of the air-cooled roller is fixed, calculate the time required for the coil head to run to the inlet of each fan, and set the fan frequency increase time and the start frequency reduction time based on the two times.

[0061] Implementation Case 1:

[0062] The current double-high-speed stripping rolling process results in a large temperature difference between the head and tail of the rolled piece (about 30°C) due to the length of the steel roller table. In addition, the coil head cannot penetrate water after rolling due to the ribbed surface, which exacerbates the temperature difference between the head and tail and seriously affects the performance stability of the coil rod. The coil head is not penetrated by water for nearly 50 meters, forming a non-cooling section. The wire-spinning temperature is about 50°C higher than that of the middle and tail sections, resulting in a large performance deviation between the head and tail. The performance of the head cannot be guaranteed, and the non-cooling section needs to be sheared before entering the market, which greatly increases metal consumption. The embodiment of the present invention discloses a production method for reducing the performance difference between the head and tail and reducing metal consumption, including:

[0063] Design of pre-water cooling gradient cooling mode after pre-finish rolling:

[0064] ① Design the pre-water cooling gradient adjustment control program;

[0065] ②Preferably use an electric control diaphragm valve with higher response accuracy;

[0066] ③Through the test process, find out the reasonable setting of gradient decline time and water volume;

[0067] ④ Compare the relationship between the temperature difference at the beginning and end and the performance difference before and after the program is put into use.

[0068] Optimizing fan control can improve the cooling intensity of the wire rod head, thereby improving the head performance and narrowing the performance difference between the head and tail.

[0069] The frequency-variable fan's frequency ramp-up gradient was optimized to be reduced by approximately 50 seconds, with a total ramp-up time designed to be 60 seconds. By connecting the steel-delivery signal from the mill's pinch rolls to the air cooling control system, the integration between the air cooling line control program and the milling line control program was optimized. After a delay after receiving the finished steel signal, the fan automatically ramps up its frequency using a newly developed program, then returns to normal frequency after a programmed high-pressure blowdown period.

[0070] The variable frequency fan repeatedly operates in this way to achieve forced cooling of the non-cooling section at the head, thereby reducing the temperature difference between the head, middle and tail of the finished product. Ultimately, while stabilizing the performance, it reduces the shearing amount at the head and tail of the coil to improve the yield rate.

[0071] Specifically, the opening adjustment and water volume reduction control process of the water tank in the pre-cooling section is as follows:

[0072] The water tank control uses a water reduction mode, triggered by a steel signal from the first pre-finishing mill. The reduction interval is set on the screen, and the reduction amplitude is programmed as a fixed value. Once the first pre-finishing mill is finished, the water level is restored to 100%, and the cycle repeats.

[0073] Also, set the total frequency ramp-up time for the variable frequency fan. This is the time required from fan startup to a maximum speed of 50 Hz (100%). This is broken down into unit frequency ramp-up times. When the cooling roller speed is fixed, calculate the time required for the coil head to reach each fan inlet. This ensures optimal air flow at the head.

[0074] By designing a pre-water cooling gradient cooling mode after pre-finishing rolling and optimizing the fan control method, the head temperature of the rolled piece after air cooling is reduced by about 30°C.

[0075] The comparison of average mechanical properties before and after implementation is shown in the following table:

[0076]

[0077] According to the test results, the performance difference between the head and tail is basically stabilized within 30Mpa. After comparison and implementation, the yield rate of small-sized coils and snails has also increased by more than 0.15%.

[0078] From simply improving the performance of the head to appropriately reducing the performance of the tail; the characteristics of the variable frequency fan are used to the maximum extent possible to achieve air cooling enhancement at different stages; and the connection between the high-speed zone signal and the air cooling line signal is completed simultaneously.

[0079] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of the present invention and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. Furthermore, each functional unit may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit.

[0080] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0081] The units described as separate components may or may not be physically separate, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0082] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical solutions and technical concepts of the present invention without creative mental work, and all of them fall within the scope of protection of the present invention.

Claims

1. A method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption, characterized in that: The following steps are involved: When the steel signal of the first stand of the pre-finishing rolling mill is detected, the water volume gradient reduction mode of the water tank is started, the time interval and the reduction amplitude of the water volume are set, and the steel throwing signal of the first stand of the pre-finishing rolling mill is detected, the water volume is restored to 100%, and the cycle repeats; The air cooling control system receives the finished steel arrival signal, and the fan automatically increases the frequency to the highest operating frequency after a set delay. After the coil head reaches the strong blowing position, the fan returns to normal frequency after the preset strong blowing time.

2. A method for reducing the poor performance of the head and tail of the spiral shell and metal consumption according to claim 1, characterized in that: The fan control methods include: Set the total frequency rise time required for the fan to rise from startup to the maximum operating frequency; Calculate the theoretical time from the coil head to the inlet of each fan; The start frequency increase time and the start frequency reduction time of the fan are set according to the total frequency increase time and the theoretical time.

3. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 2, characterized in that: The total frequency rise time is less than or equal to the difference between the theoretical time and the set delay.

4. A method for reducing the poor performance of the head and tail of the spiral shell and metal consumption according to claim 2 or 3, characterized in that: The frequency increase process of the fan is controlled by a piecewise linear frequency increase mode, which specifically includes: The low frequency band sets a first preset time required for the unit to increase the frequency; The second preset time required for the mid-frequency band to set the unit frequency up-conversion; A third preset time required for the high frequency band to set the unit frequency up-conversion; The first preset time, the second preset time and the third preset time decrease in sequence, and the interval length of the low frequency band and the interval length of the medium frequency band are both greater than the interval length of the high frequency band.

5. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 1, characterized in that: Use full linear frequency up-conversion mode to set the time required for unit frequency up-conversion.

6. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 4, characterized in that: The fan frequency reduction process adopts a segmented linear frequency reduction mode, including setting the time required for unit frequency reduction in the mid-frequency band and low-frequency band respectively.

7. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 1, characterized in that: The water volume in the water tank is controlled by installing an electric control diaphragm valve.

8. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 7, characterized in that: The decrement time interval and decrement amplitude are fixed values.

9. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 4, characterized in that: The piecewise linear upscaling modes include: The unit frequency increase in the 0-20Hz band is 0.4-0.6s / Hz; The unit frequency increase in the 20-40Hz band is 0.2-0.3s / Hz; The unit frequency increase in the 40-50Hz frequency band is 0.1-0.15s / Hz.

10. The method for reducing the poor performance of the head and tail of the spiral shell and reducing the metal consumption according to claim 8, characterized in that: The decreasing range is 3%-5%, and the decreasing time interval is 10 seconds.

Images