A Stelmor variable air volume cooling method for coil rolling

Abstract

The present invention discloses a Stelmor variable air volume cooling method for coil rolling, which belongs to the technical field of hot-rolled ribbed steel bar rolling. The present invention solves the problem that the existing method cannot eliminate the non-cooling section at the head. By calculating the time points when the coil head arrives at and leaves each cooling section, the steel signal of the head entering the pinch roller is obtained and the timing is started. When the start time of the first section fan frequency increase is reached, the fan frequency of the cooling section is increased; when the start time of the first section fan frequency increase is ended, the fan frequency of the cooling section is adjusted to the original frequency; and the fan frequency is increased according to the time point when the first coil arrives at the second cooling section, and so on; through the Stelmor fan variable air volume control, the air cooling intensity of the coil head that is not penetrated by water is increased, the influence of the non-water penetration on the mechanical properties of the coil head and the coil non-cooling section are eliminated, and the yield rate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hot-rolled ribbed steel bar rolling, in particular to a Stelmor variable air volume cooling method for coil rolling. Background Art

[0002] High-speed wire rod production lines often utilize controlled rolling and controlled cooling processes to improve coil performance. These processes primarily involve water cooling during the rolling process and air cooling on the conveyor rollers after the wire laying process. Due to the high rolling speeds and smaller gauges of high-speed wire rod, to prevent bending and buildup of steel at the head of the rolled piece due to cooling, a "closed-end" cooling process is employed after finishing rolling to ensure smooth production. This means the head section is not cooled until the rolled piece enters the laying head. This closed-end cooling process results in the coil head section not being water-cooled, resulting in higher temperatures and coarser grains than water-cooled coils. This results in a yield strength that is 10 to 30 MPa lower, or even more, than normal coil. To ensure that all sections of the coil meet standard performance requirements, the low-performing head section is often sheared off and discarded, resulting in a lower yield rate. The length of this low-performing head section is related to the distance between the finishing mill and the laying head, typically ranging from 15 to 30 meters. The industry usually adopts two methods: one is to add more alloy to improve the strength to ensure that the head performance also meets the standard requirements, but the alloy cost is high; the other is to cut off all the low-performance head coils, which has a low yield rate.

[0003] For example, publication number CN114653762B discloses a water-cooled cooling control method and system for the head of a high-speed wire rod. This solution includes acquiring a first signal when the head of the wire rod passes a first sensor; calculating a first preset time using the time at which the first signal is acquired as the starting time point; controlling a first pinch roller to clamp and transport the wire rod after the first preset time; and controlling a cooling mechanism to cool the wire rod. This method can more accurately control the length of the uncontrolled cooling section to reduce wire waste. This invention precisely controls the length of the uncontrolled cooling section through detection signals and calculation logic, but cannot eliminate the uncontrolled cooling section, which is different from the method of the present invention.

[0004] For example, publication number CN117181831A discloses a method for improving the yield rate of small-diameter, high-speed wire rods. The method includes the following steps: setting cooling medium parameters; opening the main line to control the flow of cooling medium into the front ends of several branch high-frequency quick-cut valves; opening several branch high-frequency quick-cut valves a certain time before the arrival of the high-speed wire rod head, allowing the cooling medium to be ejected from the corresponding nozzles; and after cooling is completed, closing each branch high-frequency quick-cut valve to discharge the remaining cooling medium in the branch pipes. This invention arranges the cooling water used in the high-speed wire rod water threading process at the very front end of the water tank nozzle. By digitizing the cooling water pressure and flow rate, and combining this with the high-speed response and switching time of the branch high-frequency quick-cut valves, the cooling water can be precisely sprayed after the high-speed wire rod head passes through. This reduces the length of the completely uncooled section at the wire rod head, thereby saving significant steel resources, saving significant production costs for manufacturers, and improving their economic benefits. This invention reduces the length of the uncooled section at the wire rod head through the high-speed response and development time of the high-frequency quick-cut valves, but it does not eliminate the uncooled section.

[0005] At present, the main research at home and abroad is to improve the sensitivity of the valve and control the length of the "closing head" time, which has not been able to fundamentally solve the problem of low head performance. There is no better way to solve this problem in the industry. Summary of the Invention

[0006] The object of the present invention is to provide a Stelmor variable air volume cooling method for coil rolling, which calculates the time points when the coil head arrives at and leaves each cooling section, obtains the steel signal when the head enters the clamping roller and starts timing, when the first coil enters the first cooling section, that is, when the start time of increasing the frequency of the first fan is reached, the fan frequency of the cooling section is increased; when the first coil leaves the first cooling section, that is, when the start time of increasing the frequency of the first fan ends, the fan frequency of the cooling section is adjusted to the original frequency; and the fan frequency is increased according to the time point when the first coil arrives at the second cooling section, and so on; through the variable air volume control of the Stelmor fan, the air cooling intensity of the coil head that is not penetrated by water is increased, the mechanical properties of the head are improved, the influence of the non-penetration of water on the mechanical properties of the coil head and the coil non-cooling section are eliminated, the yield rate is improved, and the problems raised in the above-mentioned background technology are solved.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A Stelmor variable air volume cooling method for coil rolling, comprising the following steps:

[0009] Step 1: Set up a cooling section on the Stelmor transport roller to blow air to cool the coil head, install a fan with variable frequency adjustment in each cooling section, connect a motor for providing driving force to each fan, and install a sensor device for detecting steel signals and a synchronous timer at the pinch roller of the coil input;

[0010] Step 2: Collect the time required for the snail head to enter the pinch roller, be spun by the spinning machine and reach the Stelmor transport roller, calculate and preset the time point when the snail head arrives at each cooling section and the time point when the snail head leaves each cooling section, and preset the adjustment plan for the fan frequency after each snail head enters each cooling section;

[0011] Step 3: Establish a control system to receive the time point when the coil head reaches each cooling section, the steel signal and the timing time. The control system adjusts the frequency of the fan in a timely manner based on the three signals;

[0012] Step 4: After the coil is rolled on the rolling mill, it is cooled in a water tank and then enters the pinch rollers. The coil is then spun onto the Stelmor conveyor roller table by a laying head. When the coil head enters the pinch rollers, the sensing device detects the steel signal in real time, the synchronous timer starts timing, and the steel signal and timing time are fed back to the control system in real time.

[0013] Step 5. The control system adjusts the fan frequency of each cooling section according to the preset time point when the coil head arrives at each cooling section based on the preset fan frequency adjustment plan; when the coil head leaves each cooling section, the fan frequency of each cooling section is restored to the normal set frequency; and when the next coil is rolled, the fan of each cooling section is increased or decreased in frequency according to the calculated preset time point to achieve variable air volume cooling for each coil.

[0014] Furthermore, in step 2, the time point when the head of the coil snail arrives at each cooling section and the time point when the head of the coil snail leaves each cooling section are calculated and preset, wherein the time point when the head of the coil snail arrives at each cooling section is the starting time when the fan increases the frequency, and the time point when the head of the coil snail leaves each cooling section is the starting time when the fan returns to the normal set frequency.

[0015] Furthermore, the start time of increasing the frequency of the fans in each cooling section is calculated as follows:

[0016] When each coil is rolled, the signal of steel being present on the pinch roller in front of the laying head is taken as the starting point. The time for increasing the frequency of the first stage fan is: The second stage fan frequency increase starts at: The start time of the third stage fan frequency increase is: The starting time of increasing the frequency of the fan in section i is:

[0017] Among them: t1, t2, t3, t i The fan opening time of each cooling section; I0, I1, I2, I3, I i is the length of each cooling section of Stelmor, in mm; V0, V1, V2, V3, V iis the transport speed of each cooling section in Stelmor, in m / s.

[0018] Furthermore, the start time for the fans in each cooling section to return to the normal set frequency is calculated as follows:

[0019] The first section of the fan returns to normal frequency setting starting time: The second stage fan returns to normal setting frequency starting time: The start time for the third stage fan to return to normal setting frequency is: The time for the fan in section i to return to normal frequency setting is:

[0020] Among them: T1, T2, T3, T i The fan of each cooling section returns to normal frequency setting start time; t1, t2, t3, t i The fan opening time of each cooling section; I0, I1, I2, I3, I i is the length of each cooling section of Stelmor, in mm; V0, V1, V2, V3, V i is the transport speed of each cooling section in Stelmor, in m / s.

[0021] Furthermore, the principle of adjusting the fan frequency in step 2 is: adjust according to the size of the coil screw. The larger the coil screw size, the greater the frequency increase of the fan.

[0022] Furthermore, the range of the fan frequency increase is: the fan frequency is increased by 5-15 Hz based on the original set frequency, but does not exceed the power frequency of 50 Hz.

[0023] Furthermore, the fan is an axial flow fan and the motor is a permanent magnet motor.

[0024] Furthermore, before the implementation of step 1, the process also includes: arranging the water tank, pinch rollers, laying out the spinning machine and the Stelmor transport roller to form a coil rolling working environment.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention arranges cooling sections and fans on the Stelmor transport roller and calculates in advance the time points when the coil head arrives at and leaves each cooling section; obtains the steel signal of the coil head entering the pinch roller through the sensing device and starts timing, when the first coil enters the first cooling section, that is, when the frequency increase start time of the first fan is reached, the fan frequency of the cooling section is increased; when the first coil leaves the first cooling section and goes to the second cooling section, that is, when the frequency increase start time of the first fan is ended, the fan frequency of the cooling section is adjusted to the original frequency; and the fan frequency is increased according to the time when the first coil arrives at the second cooling section; thereby, the wind cooling intensity of the coil head that is not penetrated by water is increased through the variable air volume control of the Stelmor fan, so as to improve the mechanical properties of the head, eliminate the influence of the non-penetration of water on the mechanical properties of the coil head, and further eliminate the coil non-cooling section, thereby improving the yield rate. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the 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.

[0028] In order to solve the technical problem of low head performance that has not been fundamentally solved by current domestic and foreign research on improving valve sensitivity and controlling the length of "closed head" time, this embodiment provides the following technical solutions:

[0029] After the coil is rolled into a finished product by the finishing mill, it is cooled by water in the cooling water tank after finishing rolling to increase its strength. Because the coil produced by wire rod is small in size, when the coil head has not entered the pinch roller, the water resistance will cause the head to pile up steel. Therefore, the coil head adopts a "closed head" water cooling process, that is: the coil head is not cooled by water, and water cooling is only carried out after the coil head enters the pinch roller; after water cooling, the coil is spun from the spinning machine to the Stelmor transport roller, and is cooled by the fan while moving forward. Because the coil head is not cooled by water, the strength of the coil head is low. In order to improve the strength of the coil head, the method of the present invention improves the strength by increasing the air cooling intensity of the head, compensating for the "closed head" after finishing rolling, that is, the head has not undergone the water cooling process, which leads to a decrease in strength. That is, when the head of each coil enters the cooling section set by Stelmor and the fan needs to be turned on, the corresponding fan motor frequency increases to increase the air volume; when the head leaves the section, the fan frequency returns to normal frequency; when the next rolled piece enters the Stelmor transport roller, the air cooling process of the previous coil is repeated, specifically:

[0030] A Stelmor variable air volume cooling method for coil rolling, comprising the following steps:

[0031] Step 1: Arrange the water tank, pinch rollers, laying head and Stelmor transport roller in order to form a coil rolling working environment; set a cooling section on the Stelmor transport roller to blow air to cool the coil head, install a fan with variable frequency adjustment in each cooling section, connect a motor for providing driving force to each fan, and install a sensor device for detecting steel signals and a synchronization timer at the pinch roller for inputting the coil;

[0032] Among them, the fan is an axial flow fan, and the fan air volume is precisely controlled by adjusting the motor speed. The axial flow fan has a large air volume. Under the condition of the same cooling effect, the motor current is small, the frequency conversion adjustment load is small, and it is easy to control the frequency conversion. Conversely, the higher the motor frequency, the faster the fan speed and the greater the air volume. In addition, the air volume of the axial flow fan has a good linear relationship with the motor speed, and the fan air volume can be precisely controlled by adjusting the motor speed.

[0033] The motor is a permanent magnet motor with variable frequency control. Since the permanent magnet synchronous motor has higher torque and lower inertia, it can achieve more precise speed regulation and torque control. It has fast acceleration and deceleration speeds and short acceleration and deceleration times, which adapts to the requirements of rapid frequency increase and decrease in this embodiment and realizes the need for rapid variable air volume.

[0034] Step 2: Collect the time required for the coil to enter the pinch roller from the head, spin through the spinning machine and reach the Stelmor transport roller, calculate and preset the time point when the coil head arrives at each cooling section and the time point when the coil head leaves each cooling section, and preset the fan frequency adjustment plan after each coil head enters each cooling section; the fan frequency adjustment principle is: adjust according to the size of the coil, the larger the coil size, the greater the fan frequency increase; the range of fan frequency increase is: the fan frequency is increased by 5-15Hz on the basis of the original set frequency, but not exceeding the industrial frequency of 50Hz; among them, the time point when the coil head arrives at each cooling section is: the start time of the fan frequency increase, and the time point when the coil head leaves each cooling section is: the start time of the fan frequency increase; calculate the start time of the fan frequency increase in each cooling section, specifically:

[0035] When each coil is rolled, the signal of steel being present on the pinch roller in front of the laying head is taken as the starting point. The time for increasing the frequency of the first stage fan is: The second stage fan frequency increase starts at: The start time of the third stage fan frequency increase is: The starting time of increasing the frequency of the fan in section i is:

[0036] Among them: t1, t2, t3, t i The fan opening time of each cooling section; I0, I1, I2, I3, I iis the length of each cooling section of Stelmor, in mm; V0, V1, V2, V3, V i is the transport speed of each cooling section in Stelmor, in m / s.

[0037] Calculate the start time for each cooling section fan to return to normal set frequency, specifically:

[0038] The first section of the fan returns to normal frequency setting starting time: The second stage fan returns to normal setting frequency starting time: The start time for the third stage fan to return to normal setting frequency is: The time for the fan in section i to return to normal frequency setting is:

[0039] Among them: T1, T2, T3, T i The fan of each cooling section returns to normal frequency setting start time; t1, t2, t3, t i The fan opening time of each cooling section; I0, I1, I2, I3, I i is the length of each cooling section of Stelmor, in mm; V0, V1, V2, V3, V i is the transport speed of each cooling section in Stelmor, in m / s.

[0040] Specifically, for 6mm coils, the frequency of the axial flow fan is increased by 5Hz, for 8mm coils, the frequency of the axial flow fan is increased by 10Hz, and for 10mm coils, the frequency of the axial flow fan is increased by 15Hz; only the fan that is set to be turned on increases the frequency, and the fan that is not set to be turned on does not increase the frequency; and this method is applied to the production of wire coils, the Stelmor fan runs stably, and the yield strength of the produced coil head is 0 to 15MPa higher than the yield strength of the normal part, and other mechanical properties meet the standard requirements; secondly, Examples 1-6 are applied to this method, and the parameters of the Stelmor fan are shown in Table 1. Comparative Examples 1-6 are produced according to conventional methods, and the cooling intensity of the coil head is not increased; the mechanical properties of the examples and comparative examples are shown in Table 2, among which the yield strength of the head of the examples is 2 to 10MPa higher than the yield strength of other parts, and other mechanical properties meet the standard requirements, and the yield strength of the head of the comparative example is 12 to 23MPa lower than the yield strength of other parts.

[0041]

[0042] Table 1 is the parameters of the Stelmor blower in the embodiment and comparative example of the present invention.

[0043]

[0044]

[0045] Table 2 shows the mechanical properties of the embodiments and comparative examples of the present invention.

[0046] Step three, establish a control system for receiving the time point when the coil head reaches each cooling section, the steel signal and the timing time. The control system timely adjusts the frequency of the fan based on the three signals; specifically, the control system is used to provide the function of sending and receiving instructions for the Stelmore variable air volume cooling method. The control system timely controls the axial flow fan to change the air volume at the specified frequency according to the received steel signal, the preset time point and the axial flow fan frequency adjustment plan, thereby improving the strength of the coil head and reducing the coil failure rate.

[0047] Step 4: After the coil is rolled on the rolling mill, it is cooled in a water tank and then enters the pinch rollers. The coil is then spun onto the Stelmor conveyor roller table by a laying head. When the coil head enters the pinch rollers, the sensing device detects the steel signal in real time, the synchronous timer starts timing, and the steel signal and timing time are fed back to the control system in real time.

[0048] Step 5. The control system adjusts the fan frequency of each cooling section according to the preset time point when the coil head arrives at each cooling section based on the preset fan frequency adjustment plan; when the coil head leaves each cooling section, the fan frequency of each cooling section is restored to the normal set frequency; and when the next coil is rolled, the fan of each cooling section is increased or decreased in frequency according to the calculated preset time point to achieve variable air volume cooling for each coil.

[0049] The beneficial effects achieved by the above content are: through the above operation, the variable air volume control of the Stelmor blower is used to increase the air cooling intensity of the head of the coil that is not penetrated by water, so as to improve the mechanical properties of the head, eliminate the influence of the non-penetration of water on the mechanical properties of the coil head, eliminate the non-cooling section of the coil, and improve the yield rate.

[0050] Working principle: After the coil is rolled on the rolling mill, it is cooled in a water tank and then enters the pinch roller. It is spun onto the Stelmor transport roller by the spinning machine. When the coil head enters the pinch roller, a steel signal is detected and the timing starts. The fans in each cooling section increase the frequency according to the pre-calculated start time for the fans to increase the frequency. When the coil head leaves each cooling section, the frequency is reduced according to the pre-calculated start time for the fans to return to the normal set frequency. When the next coil is rolled, the fans in each cooling section increase or decrease the frequency according to the above logic to achieve variable air volume cooling for each coil, thereby improving the cooling intensity of the coil head and thus improving the head strength.

[0051] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0052] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A Stelmor variable air volume cooling method for coil rolling, characterized in that: The following steps are involved: Step 1: Set up a cooling section on the Stelmor transport roller to blow air to cool the coil head, install a fan with variable frequency adjustment in each cooling section, connect a motor for providing driving force to each fan, and install a sensor device for detecting steel signals and a synchronous timer at the pinch roller of the coil input; Step 2: Collect the time required for the snail head to enter the pinch roller, be spun by the spinning machine and reach the Stelmor transport roller, calculate and preset the time point when the snail head arrives at each cooling section and the time point when the snail head leaves each cooling section, and preset the adjustment plan for the fan frequency after each snail head enters each cooling section; Step 3: Establish a control system to receive the time point when the coil head reaches each cooling section, the steel signal and the timing time. The control system adjusts the frequency of the fan in a timely manner based on the three signals; Step 4: After the coil is rolled on the rolling mill, it is cooled in a water tank and then enters the pinch rollers. The coil is then spun onto the Stelmor conveyor roller table by a laying head. When the coil head enters the pinch rollers, the sensing device detects the steel signal in real time, the synchronous timer starts timing, and the steel signal and timing time are fed back to the control system in real time. Step 5: The control system adjusts the fan frequency of each cooling section according to the preset time point when the snail head reaches each cooling section based on the preset fan frequency adjustment plan; when the snail head leaves each cooling section, the fan frequency of each cooling section is restored to the normal set frequency; When the next coil is rolled, the fans in each cooling section are increased or decreased in frequency according to the calculated preset time points to achieve variable air volume cooling for each coil.

2. The Stelmor variable air volume cooling method for coil rolling according to claim 1, characterized in that: In step 2, the time point when the head of the coil snail arrives at each cooling section and the time point when the head of the coil snail leaves each cooling section are calculated and preset. Among them, the time point when the head of the coil snail arrives at each cooling section is the starting time when the fan increases the frequency, and the time point when the head of the coil snail leaves each cooling section is the starting time when the fan returns to the normal set frequency.

3. The Stelmor variable air volume cooling method for coil rolling according to claim 1, characterized in that: The principle of adjusting the fan frequency in step 2 is: adjust according to the size of the coil screw. The larger the coil screw size, the greater the frequency increase of the fan.

4. The Stelmor variable air volume cooling method for coil rolling according to claim 3, characterized in that: The range of fan frequency increase is: the fan frequency increases by 5-15Hz based on the original set frequency, but does not exceed the industrial frequency of 50Hz.

5. The Stelmor variable air volume cooling method for coil rolling according to claim 1, characterized in that: The fan is an axial flow fan, and the motor is a permanent magnet motor.

6. The Stelmor variable air volume cooling method for coil rolling according to claim 1, characterized in that: Before the implementation of step one, it also includes: arranging the water tank, pinch rollers, laying out the wire drawing machine and Stelmor transport roller to form a coil rolling working environment.

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