3# flying shear shearing length and precision control method and bar production method

Abstract

The embodiment of the application provides a 3# flying shear cutting length and precision control method and a bar production method, and relates to the bar cutting technology field for rolling. The 3# flying shear cutting length and precision control method comprises the following steps: determining a pulse equivalent standard value, the pulse equivalent standard value is accurate to a hot metal detector measured value, when adjusting a roll reduction, replacing the hot metal detector, adjusting a hot metal detector angle and sensitivity, adjusting a hot metal detector position or adding water cooling, the pulse equivalent standard value is calculated according to a roll working roll diameter * M, when the system is stable, the pulse equivalent standard value is restored to be accurate to the hot metal detector measured value; tail steel processing, calculating the length of the whole steel according to the pulse equivalent standard value, calculating the number of cutting knives and the length of the tail steel according to the length of the whole steel, and adjusting the segmented length according to the calculated length of the tail steel, so that the tail steel is not too long or too short. The 3# flying shear method reduces short lengths, cutting losses and rolling costs.

Description

Technical Field

[0001] This invention relates to the field of bar shearing technology for steel rolling, and more specifically, to a method for controlling the shearing length and precision of a No. 3 flying shear and a bar production method. Background Technology

[0002] With the continuous development and technological advancements in the steel industry, modern steel rolling production lines have made significant progress in improving production efficiency and product quality. Especially in the rolling processes of bars and wire rods, the application of automated continuous rolling technology has greatly improved production efficiency. However, in actual production, some technical challenges still need to be overcome. For example, in the automated continuous rolling process with water cooling, the low shearing accuracy of the flying shear leads to a large number of short lengths and increased cutting losses, which in turn affects the yield and the accuracy of negative tolerance control.

[0003] To ensure rolling quality and production efficiency, automatic control systems are typically used to monitor and adjust rolling parameters. However, when changes occur in the workpiece or individual parameters cannot be accurately obtained, these automatic control systems may struggle to precisely adjust shearing parameters, thus affecting the shearing accuracy of the flying shear. This not only leads to inconsistencies in product dimensions but also increases the scrap rate, making it difficult to effectively control the yield and increasing rolling costs. Furthermore, poor negative tolerance control accuracy can also adversely affect product output.

[0004] Therefore, under the current technological background, reducing the phenomenon of short lengths and cutting losses has become the key to improving the yield and controlling the rolling cost. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling the cutting length and precision of a No. 3 flying shear and a bar production method, which can reduce short length phenomenon and cutting damage, thereby improving the yield and controlling the rolling cost.

[0006] The embodiments of the present invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a method for controlling the cutting length and precision of a #3 flying shear, comprising:

[0008] The standard value of pulse equivalent is determined based on the value measured by the hot metal detector. When the roll reduction is adjusted, the hot metal detector is replaced, the measuring angle and sensitivity of the hot metal detector are adjusted, the measuring position of the hot metal detector is adjusted, or water cooling is added, the standard value of pulse equivalent is calculated by the working roll diameter × M until a dimensionally qualified rolled piece is obtained and the pulse equivalent fluctuation measured by the hot metal detector is less than or equal to the preset value A. At this point, the standard value of pulse equivalent is restored to the value measured by the hot metal detector.

[0009] For tail steel processing, the length of the entire steel bar is calculated based on the pulse equivalent standard value. The number of shearing cuts and the tail steel length are then calculated based on the total steel bar length. At this point:

[0010] If the length of the entire steel bar fluctuates within plus or minus two multiples of a length, and the calculated tail steel length can still be placed on the cooling bed even with an increase of two fixed lengths, then the last cut is not made.

[0011] If the calculated number of shearing cuts is greater than 20 and the tail steel has a short tail, then starting from the first cut, each segment of steel will be reduced by one length until the short tail phenomenon is eliminated.

[0012] If the length of the entire steel bar fluctuates within a range of more than two multiples of a ruler, then the segment length of the last i-th cut can fluctuate within a range of extending by one multiple of a ruler and shortening by three multiples of a ruler, so that the tail steel is within a preset range, where i is a positive integer less than 3.

[0013] In an optional implementation, the pulse equivalent fluctuation refers to the maximum deviation of n consecutively measured pulse equivalents, where n ≥ 5.

[0014] In an optional implementation, when the pulse equivalent is based on the value measured by the hot metal detector, if the deviation of any of the n consecutively measured pulse equivalents is greater than a preset value B, then the pulse equivalent measurement result corresponding to the deviation greater than the preset value B is discarded.

[0015] In an optional implementation, the preset value B is less than 5%.

[0016] In an optional implementation, M is any value between 103% and 105%;

[0017] And / or, the preset value A is less than 2‰.

[0018] In an optional implementation, when the pulse equivalent standard value is based on the value measured by the hot metal detector, as the pulse equivalent of the No. 3 flying shear gradually decreases during operation, when the pulse equivalent decreases to the preset value C, the roll reduction is adjusted so that the pulse equivalent returns to the pulse equivalent standard value.

[0019] In an optional implementation, when the pulse equivalent is based on the value measured by the hot metal detector, the pulse equivalent is based on the average value of n consecutively measured pulse equivalents, where n ≥ 5.

[0020] In an optional implementation, thermal detector #0 is installed after flying shear #1 and between frame #7 and frame #8.

[0021] In an optional implementation, if the random error of the hot metal detector is large, at least one of the following AD measures can be taken:

[0022] A. Install a fan to disperse the mist and moisture between the rolled piece and the hot inspection area;

[0023] B. Check for iron oxide deposits inside the conduit and remove any accumulated iron oxide deposits.

[0024] C. Increase the water cooling temperature to increase the surface brightness of the rolled piece;

[0025] D. Replace the thermal detection with a low-temperature thermal detection.

[0026] Secondly, the present invention provides a method for producing bar stock, comprising: controlling a No. 3 flying shear using the No. 3 flying shear cutting length and precision control method described in any one of the foregoing embodiments.

[0027] The beneficial effects of the method for controlling the shearing length and precision of the No. 3 flying shear and the method for producing bar stock provided in this embodiment of the invention include:

[0028] The method for controlling the cutting length and precision of the No. 3 flying shear in this application, compared with determining the pulse equivalent solely based on thermal inspection data or solely based on the roller ring diameter combined with the slip value, can reduce short length phenomenon and cutting damage, and further reduce rolling costs. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0030] Therefore, the following detailed description of the embodiments is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," and "outer" are used to indicate the orientation or positional relationship that the product of this invention is usually placed in, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0032] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0033] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0034] This invention provides a method for controlling the cutting length and precision of a #3 flying shear, comprising:

[0035] The standard value of pulse equivalent is determined based on the value measured by the hot metal detector. When the roll reduction is adjusted, the hot metal detector is replaced, the measuring angle and sensitivity of the hot metal detector are adjusted, the measuring position of the hot metal detector is adjusted, or water cooling is added, the standard value of pulse equivalent is calculated by the working roll diameter × M until a dimensionally qualified rolled piece is obtained and the pulse equivalent fluctuation measured by the hot metal detector is less than or equal to the preset value A. At this point, the standard value of pulse equivalent is restored to the value measured by the hot metal detector.

[0036] For tail steel processing, the length of the entire steel bar is calculated based on the pulse equivalent standard value. The number of shearing cuts and the tail steel length are then calculated based on the total steel bar length. At this point:

[0037] If the length of the entire steel bar fluctuates within plus or minus two multiples of a length, and the calculated tail steel length can still be placed on the cooling bed even with an increase of two fixed lengths, then the last cut is not made.

[0038] If the calculated number of shearing cuts is greater than 20 and the tail steel has a short tail, then starting from the first cut, each segment of steel will be reduced by one length until the short tail phenomenon is eliminated.

[0039] If the length of the entire steel bar fluctuates within a range of more than two multiples of a ruler, then the segment length of the last i-th cut can fluctuate within a range of extending by one multiple of a ruler and shortening by three multiples of a ruler, so that the tail steel is within a preset range, where i is a positive integer less than 3.

[0040] In an optional implementation, the pulse equivalent fluctuation refers to the maximum deviation of n consecutively measured pulse equivalents, where n ≥ 5.

[0041] In an optional implementation, when the pulse equivalent is based on the value measured by the hot metal detector, if the deviation of any of the n consecutively measured pulse equivalents is greater than a preset value B, then the pulse equivalent measurement result corresponding to the deviation greater than the preset value B is discarded.

[0042] In an optional implementation, the preset value B is less than 5%.

[0043] In an optional implementation, M is any value between 103% and 105%;

[0044] And / or, the preset value A is less than 2‰.

[0045] In an optional implementation, when the pulse equivalent standard value is based on the value measured by the hot metal detector, as the pulse equivalent of the No. 3 flying shear gradually decreases during operation, when the pulse equivalent decreases to the preset value C, the roll reduction is adjusted so that the pulse equivalent returns to the pulse equivalent standard value.

[0046] In an optional implementation, when the pulse equivalent is based on the value measured by the hot metal detector, the pulse equivalent is based on the average value of n consecutively measured pulse equivalents, where n ≥ 5.

[0047] In an optional implementation, if the random error of the hot metal detector is large, such as when more than three out of ten pulse equivalent measurements exceed the preset value B, at least one of the following AD measures can be taken:

[0048] A. Install a fan to disperse the mist and moisture between the rolled piece and the hot inspection area;

[0049] B. Check for iron oxide deposits inside the conduit and remove any accumulated iron oxide deposits.

[0050] C. Increase the water cooling temperature to increase the surface brightness of the rolled piece;

[0051] D. Replace the thermal detection with a low-temperature thermal detection.

[0052] In principle, the pulse encoder on the exit stand directly and accurately reflects the rotation angle of the rolls. During measurement, the roll rotation angle is directly proportional to the length of the rolled piece; that is, each pulse from the exit stand pulse encoder represents a fixed length of rolled piece travel, i.e., the pulse equivalent. The shearing length of the #3 flying shear depends entirely on the accuracy and stability of the pulse equivalent. In other words, shearing length = pulse equivalent × number of pulses. With the exit stand speed constant, the magnitude of the pulse equivalent directly affects the shearing accuracy. Therefore, finding the accurate pulse equivalent and maintaining its stability are crucial.

[0053] The process involves two roll diameters: the working roll diameter and the roll ring diameter. The exit line speed set on the rolling line is calculated based on the working roll diameter. However, the actual linear speed of the rolled piece is faster than the set exit line speed because the rolled piece experiences a certain amount of forward slippage after being squeezed by the rolls. This forward slippage value is generally between 3% and 5%. Therefore, when setting the working roll diameter in a flying shear, it can be set as the process working roll diameter × (103% - 105%). The roll ring diameter is the maximum diameter of the installed rolls. Therefore, when the roll diameter is not accurately estimated, the working roll diameter can be set based on the roll ring diameter initially. When calculating the pulse equivalent in this way, both the working roll diameter and the forward slippage M are estimated values ​​and cannot be accurately obtained, thus introducing errors.

[0054] Furthermore, during the steel rolling process, the working roll diameter can change over time due to factors such as roll reduction adjustment, roll wear, and roll deformation caused by temperature variations. The pulse equivalent standard value, calculated as working roll diameter × M, is always used for length measurement, speed measurement, and shearing based on the set roll diameter and cannot automatically adjust to changes in roll diameter. Therefore, in the initial stage of steel rolling, i.e., the first steel rolling after commissioning, or the first steel rolling after replacing the hot detector, adjusting the hot detector angle and sensitivity, adjusting the hot detector position, or adding water cooling, when the operator does not trust the hot detector, the pulse equivalent standard value is calculated as the working roll diameter × M. After the roll reduction is adjusted and the rolled piece dimensions are qualified, after rolling several steels, if the deviation of the measured value of the pulse equivalent of the hot detector is within the preset value A, such as 2‰, then the system can be considered to be running relatively stably and the hot detector result is relatively accurate. At this time, the pulse equivalent standard value can be based on the value measured by the hot metal detector. At this time, the working roll diameter can be calculated back from the average value of n pulse equivalents to correct the working roll diameter in the system.

[0055] It should be noted that if the system can only calculate the pulse equivalent based on the working roll diameter and cannot directly correlate the thermal detection result with the pulse equivalent, then during the steel rolling process, it is important to observe the length measurement record. As time goes by, the operator will find that the measured pulse equivalent will become smaller and smaller, and the length of the sheared steel will also become shorter and shorter. At this time, the roll diameter can be rewritten to correct the roll diameter.

[0056] Furthermore, a decreasing pulse equivalent indicates a decreasing roll diameter, which may be caused by roll wear. In this case, the roll reduction can be adjusted. After the roll reduction is adjusted and the workpiece dimensions are qualified, and after rolling several steel pieces, when the thermal testing results are relatively stable, the roll diameter can be corrected.

[0057] In addition, if the pulse equivalent changes, and the roll reduction is adjusted to restore the pulse equivalent to its original value, the roll diameter does not need to be corrected.

[0058] It should be noted that although determining the pulse equivalent based on the thermal detection results is highly accurate and can automatically adapt to changes in roller diameter after the equipment is running stably, it also has the following drawbacks:

[0059] 1. Random errors are easily generated, potentially exceeding the preset value. Determining the pulse equivalent value based on the thermal detection results depends entirely on whether the workpiece head can be accurately detected instantaneously as it passes through the #1 and #2 hot metal detectors. The following situations may cause sudden changes and inaccuracies in the measured values:

[0060] The head of the rolled piece is too cold, causing it to turn black; excessive fogging or blackening of the rolled piece when water cooling is used; accumulation of iron oxide chips in the detection guide tube; the steel appearing and disappearing intermittently when it jumps; poor HMD detection conditions, such as an incorrect optical path or a dirty lens, result in reduced sensitivity and inability to accurately detect the steel head at the moment of arrival.

[0061] The following methods can be used to remedy this:

[0062] 1. When water cooling is used, add a fan to blow air along the hot inspection direction towards the rolled piece to disperse the mist and moisture.

[0063] 2. Check regularly for any accumulation of iron oxide filings and remove them promptly.

[0064] 3. If the process permits, increase the water cooling temperature to prevent the surface of the rolled piece from becoming too dark.

[0065] 4. Please carefully check the environmental conditions of the HMD, and try adjusting the thermal detection angle and sensitivity to ensure it is in optimal working condition. If other causes have been ruled out, consider replacing it with a low-temperature HMD.

[0066] 5. In electrical systems, in order to reduce the impact of random errors, the average value of multiple measurement records, such as 10, is used as the pulse equivalent in use, thereby eliminating the impact of measurement abrupt changes.

[0067] 6. In electrical systems, to eliminate the impact of sudden measurement changes, a sudden change rejection button has been added to the measurement recording screen. This means that after ten measurement records have stabilized, clicking the sudden change rejection button activates the sudden change rejection function. At this point, if a measurement value suddenly deviates from the original average value by a preset value, such as 5‰, it will be deleted.

[0068] In an optional implementation, thermal detector #0 is installed after flying shear #1 and between frame #7 and frame #8.

[0069] To reduce short lengths and cutting losses, a relatively accurate tail steel length is needed. The determination of the tail steel length is closely related to the overall length of the steel and the number of shearing blades. Provided that the pulse equivalent is accurate, and the rolling line operates stably with accurate hot inspection, the overall length of the steel can be obtained with reasonable accuracy.

[0070] Specifically, after several steel bars have been rolled stably, the operator can basically determine the length of the product that can be rolled from the whole billet when rolling this specification of product by recording the cutting length. They can further determine how many whole multiples of the length (i.e. the number of shearing blades) and the length of the end section (tail steel) will be included when rolling a steel billet according to the set cutting length. That is, the length of the whole steel bar = cutting length × number of shearing blades + length of the end section (tail steel).

[0071] It should be noted that after rolling several steel bars, the measured average length can be entered into the system to facilitate the electrical system to obtain relatively accurate data.

[0072] When the number of cutting cuts by the flying shear is fixed, and the actual measured length of the rolled product does not fluctuate significantly (within plus or minus two multiples of the length), and the product can still be loaded onto the cooling bed after being extended by two lengths, the last cut can be skipped to prevent short tails when the length fluctuates. For example: Normally, the flying shear cuts 10 times, resulting in a cutting length of 97 meters, a fixed length of 12 meters, and a tail length of approximately 90 meters; if the length fluctuates by about 20 meters, and the tail length is over 110 meters, it can still be loaded onto the cooling bed. In this case, the 11th cut can be increased by two multiples in the length adjustment screen, so that the 11th cut does not cut within 120 meters.

[0073] When the length of the rolled piece is too long and the number of shearing cuts is greater than 20, in order to avoid short tails, the length must be changed to a multiple of the length in the first few cuts to eliminate short tails.

[0074] If the length of the rolled piece fluctuates by more than two multiples (e.g., four multiples, approximately 40 meters), then to prevent short tails, the length of the last two or three cuts must be automatically adjusted (this is related to the location of the hot inspection 0 and the rolling size; the farther the hot inspection 0 is from the slitting shear or the smaller the rolling size, the more cuts are left; installing the hot inspection 0 after the #1 flying shear, between #7 and #8 stands, helps to calculate the total length of the entire steel bar earlier, thus allowing for earlier intervention in length adjustment). Specifically, if the rolled piece is too long, the length of the last few cuts will be increased by multiples; if the rolled piece is too short, the length of the last few cuts will be decreased by multiples. The purpose is to ensure that the tail steel is placed on the cooling bed when the billet size changes slightly.

[0075] Tail extension: The multiple of the difference between the target length of the tail steel and the normal cutting length (e.g., +1 means adding one fixed length, -1 means reducing one fixed length).

[0076] The preset range of tail steel, i.e. the tail end degrees of freedom: the number of multiples by which the actual length of the tail steel is allowed to differ from the target length of the tail steel (cannot be a positive value. For example, -1 means that the allowable deviation is 1 fixed length).

[0077] Optimize and adjust the upper / lower limits: Allow adjustment of the multiple of the difference between the length of the last two / three cuts and the normal cutting length.

[0078] The length is recorded starting when the rolled piece passes through the #0 hot inspection gate and ends when the tail of the rolled piece leaves the #0 hot inspection gate. At this point, the system predicts the total length of the rolled piece and calculates the remaining length and the number of cuts based on the length already cut by the flying shear. When the tail steel exceeds the set range, the length of the remaining cuts is adjusted to a multiple of the length to ensure that the tail steel falls within the set range.

[0079] Specifically, in some embodiments: the 0# hot shear is installed between the 7# and 8# frames, the length of the cooling bed is 120 meters, the length of the finished product is 9 meters, the number of multiple length pieces is 11, the additional length is 0.5 meters, the shrinkage rate is 0.99, and the segment length is 100.0506.

[0080] Analysis: Considering a 5-meter distance at the front and back of the cooling bed, the maximum segment length can reach approximately 110 meters;

[0081] Considering the cooling bed's operating cycle is 3.5 seconds and the maximum rolling speed is 18 meters, the minimum length of the upper cooling bed segment is 18 × 3.5 = 63 meters.

[0082] Optimized parameter settings: Tail end extension = 0, that is, the target length of the tail steel is the segment length = 100.0506;

[0083] The tail end has a degree of freedom of -2, which means that the actual length of the tail steel is allowed to differ from the target length of the tail steel by 2 times, that is, the length of the tail steel can be between 82 meters and 100 meters.

[0084] The optimization adjustment limit is set to 1, which means that the length of the last two or three cuts can be automatically adjusted to be one time length longer than the normal cutting length, that is, the length of the last two or three cuts can be adjusted to about 109 meters.

[0085] The optimization adjustment limit is set to -3, which means that the length of the last two or three cuts can be automatically adjusted to be three times shorter than the normal cutting length, that is, the length of the last two or three cuts can be adjusted to about 73 meters.

[0086] Following the above method, when the tail of the rolled piece leaves the 0# hot inspection area, if there are 2 cuts remaining and the tail steel is within 18 meters, then the adjustment is to cut approximately 109 meters with the last cut, and then stop cutting when approximately 109 meters remain. At this point, the tail steel will be around 109 meters. If there are 2 cuts remaining and the tail steel is more than 20 meters remaining, then the adjustment is to automatically shorten the last two cuts by the corresponding multiples (each cut shortens by a maximum of 3 multiples) so that the tail steel falls between 82 meters and 100 meters.

[0087] It is important to note that the ratio between the running length of the rolled piece and the rotation angle of the roll (i.e., the pulse equivalent) is affected by many factors. Among them, the fluctuation of the cross-sectional dimensions of the rolled piece and the temperature difference between the head and tail directly affect the running length of the rolled piece per roll revolution (i.e., the pulse equivalent), thus significantly affecting the shearing accuracy and the predicted length.

[0088] The present invention also provides a method for producing bars, comprising: controlling a No. 3 flying shear using the No. 3 flying shear cutting length and precision control method described in any one of the foregoing embodiments.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the cutting length and precision of a No. 3 flying shear, characterized in that, include: The standard value of pulse equivalent is determined based on the value measured by the hot metal detector. After adjusting the roll reduction, replacing the hot metal detector, adjusting the measuring angle and sensitivity of the hot metal detector, adjusting the measuring position of the hot metal detector, or adding water cooling, the standard value of pulse equivalent is calculated by multiplying the working roll diameter by M, where M is any value between 103% and 105%, until a dimensionally qualified rolled piece is obtained and the pulse equivalent fluctuation measured by the hot metal detector is less than or equal to the preset value A. At this point, the standard value of pulse equivalent is restored to the value measured by the hot metal detector, where the preset value A is less than 2‰. For tail steel processing, the length of the entire steel bar is calculated based on the pulse equivalent standard value. The number of shearing cuts and the tail steel length are then calculated based on the total steel bar length. At this point: If the length of the entire steel bar fluctuates within plus or minus two multiples of a length, and the calculated tail steel length can still be placed on the cooling bed even with an increase of two fixed lengths, then the last cut is not made. If the calculated number of shearing cuts is greater than 20 and the tail steel has a short tail, then starting from the first cut, each segment of steel will be reduced by one length until the short tail phenomenon is eliminated. If the length of the entire steel bar fluctuates within a range of more than two multiples of a ruler, then the segment length of the last i cuts will fluctuate within a range of extending by one multiple of a ruler and shortening by three multiples of a ruler, so that the tail steel is within the preset range, where i is a positive integer less than 3; When the pulse equivalent is based on the value measured by the hot metal detector, if the deviation of any of the n consecutively measured pulse equivalents is greater than the preset value B, the pulse equivalent measurement result corresponding to the deviation greater than the preset value B is discarded; the preset value B is less than 5%.

2. The method for controlling the cutting length and precision of the No. 3 flying shear according to claim 1, characterized in that, The pulse equivalent fluctuation refers to the maximum deviation of n consecutively measured pulse equivalents, where n ≥ 5.

3. The method for controlling the cutting length and precision of the No. 3 flying shear according to claim 1, characterized in that, When the pulse equivalent is based on the value measured by the hot metal detector, the pulse equivalent is based on the average value of n consecutively measured pulse equivalents, where n ≥ 5.

4. The method for controlling the cutting length and precision of the No. 3 flying shear according to claim 1, characterized in that, The No. 0 hot metal detector is installed after the No. 1 flying shear and between the No. 7 and No. 8 frames.

5. The method for controlling the cutting length and precision of the No. 3 flying shear according to claim 1, characterized in that, If the random error of the hot metal detector exceeds a preset value, at least one of the following AD measures shall be taken: A. Install a fan to disperse the mist and moisture between the rolled piece and the hot metal detector; B. Check for iron oxide deposits inside the conduit and remove any accumulated iron oxide deposits. C. Increase the water cooling temperature to increase the surface brightness of the rolled piece; D. Replace the hot metal detector with a low-temperature hot metal detector.

6. A method for producing bars, characterized in that, include: The No. 3 flying shear is controlled using the No. 3 flying shear cutting length and precision control method described in any one of claims 1-5.