Multi-rack continuous rolling speed cooperative control method for bar rolling production line

Abstract

The invention relates to the technical field of bar multi-rack continuous rolling, and discloses a bar rolling production line multi-rack continuous rolling speed cooperative control method which comprises the steps of (1) speed reference setting before rolling, (2) speed dynamic adjustment in the rolling process, (3) abnormal working condition cooperative response and (4) speed stability maintenance. By means of the closed-loop control logic of reference setting before rolling and dynamic adjustment in rolling, in combination with cascade speed grouping (rough rolling and intermediate rolling grouping linkage) and 5%-8% of speed buffer areas between the groups, the speed ratio and the extension coefficient of the adjacent racks are accurately matched, the speed matching error is controlled within 1%, and the speed matching precision is greatly improved. The problem of speed imbalance caused by roller abrasion (for example, the roller diameter is reduced by 5 mm) and temperature fluctuation (+ / -50 DEG C) in traditional static setting is effectively solved, and the accident rate of steel piling and steel pulling in the interval from rough rolling to intermediate rolling and from pre-finish rolling to finish rolling is reduced by 60% or above.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-stand continuous rolling of bar, in particular to a multi-stand continuous rolling speed coordination control method for bar rolling production line. BACKGROUND

[0002] Multi-stand continuous rolling of bar is a key process to achieve efficient and high-quality production. In particular, in a small and medium-sized bar special steel production line, the rolling requirements of multiple steel grades (specifications Φ20~100mm) such as joint steel, gear steel, bearing steel, etc. need to be considered, and the design annual capacity reaches 600,000 tons. The core logic is to realize no-torsion micro-tension rolling by using the rolling mill arranged in a flat-stand alternation manner through continuous rolling of the rough rolling, intermediate rolling, pre-precision rolling, precision rolling and reducing sizing unit, and to ensure the product size precision and mechanical properties by cooperating with controlled rolling and controlled cooling process (such as low-temperature rolling temperature as low as 750℃).

[0003] From the actual production process, the rolled piece needs to go through the links of heating (950~1200℃), descaling, multi-pass rolling, water cooling, shearing, cooling bed cooling, etc., and the speeds of each stand need to be strictly matched: the rough rolling inlet speed is 0.16~0.3m / s, the intermediate rolling inlet speed is 0.36~1.26m / s, the pre-precision rolling inlet speed is 0.9~2.96m / s, and the precision rolling outlet speed is as high as 18m / s. The core of speed coordination is to ensure that there is no steel stacking and no steel pulling between the stands, that is, to reasonably distribute through the extension coefficient (rough rolling 1.2~1.3, precision rolling 1.1~1.2) so that the speed ratio of adjacent stands is consistent with the deformation requirement of the rolled piece.

[0004] However, the existing speed control method has obvious limitations: Static setting is difficult to adapt to dynamic changes: the traditional method sets the speed of each stand according to a fixed ratio, without considering the roll wear (such as the reduction of roll diameter when the rolling groove rolling tonnage reaches the limit), temperature fluctuations (heating furnace outlet temperature difference ±50℃) and steel grade differences (such as different deformation resistances of spring steel and non-quenched and tempered steel), resulting in that the actual speed ratio deviates from the theoretical value. For example, if the actual roll diameter of the rough rolling unit is reduced by 5mm due to roll wear, and the speed is not adjusted accordingly, it will cause the rolled piece to be stacked due to insufficient speed when entering the intermediate rolling.

[0005] Insufficient tension and loop coordination: the height of the vertical loop between the pre-precision rolling and the precision rolling is set to 100~150mm. If the speed of the upstream stand is too fast, the loop height will exceed the upper limit, causing the rolled piece to stretch; if the speed of the downstream stand is too fast, the loop height will be insufficient, causing the rolled piece to be stacked. The existing control responds to the deviation of the loop height with a delay (adjustment is made when the deviation exceeds ±20mm), which easily causes the size of the rolled piece to be out of tolerance (diameter tolerance >±0.3mm). SUMMARY

[0006] (I) Technical problems solved In view of the deficiencies of the prior art, the present application provides a multi-stand continuous rolling speed coordination control method for a bar rolling production line, which has the advantages of improving rolling stability, reducing steel piling and drawing accidents, and solves the problem that static setting is difficult to adapt to dynamic changes.

[0007] (II) Technical solutions To achieve the above-mentioned purposes of improving rolling stability and reducing steel piling and drawing accidents, the present application provides the following technical solutions: a multi-stand continuous rolling speed coordination control method for a bar rolling production line, comprising the following steps: step 1: pre-rolling speed reference setting, step 2: rolling process speed dynamic adjustment, step 3: abnormal condition coordination response, and step 4: speed stability maintenance; the step 1: pre-rolling speed reference setting comprises steps 101: basic parameter confirmation and 102: cascade speed grouping. The step 2: rolling process speed dynamic adjustment comprises steps 201: micro-tension control and 202: speed synchronization correction. The step 3: abnormal condition coordination response comprises steps 301: steel piling / drawing treatment and 302: speed resetting after roll changing. The step 4: speed stability maintenance comprises steps 401: regular calibration and 402: data feedback optimization.

[0008] Preferably, the step 101: basic parameter confirmation. According to the rolling piece specifications (Φ20~100mm) and the design of the hole patterns of each stand, the extension coefficient ranges of the rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling and reducing sizing unit are determined: rough rolling 1.2~1.3, intermediate rolling 1.25~1.35, pre-finishing rolling 1.15~1.25, finishing rolling 1.1~1.2, and reducing sizing 1.05~1.15. Taking the finished product target speed as the reference (finishing rolling outlet speed 0.83~18m / s, adjusted according to the specifications), the theoretical speeds of each stand are deduced in reverse order of “finishing rolling→pre-finishing rolling→intermediate rolling→rough rolling”, to ensure that the speed ratios of adjacent stands and the extension coefficients are matched, and the rough rolling inlet speed is controlled at 0.16~0.3m / s, the intermediate rolling inlet speed is 0.36~1.26m / s, and the pre-finishing rolling inlet speed is 0.9~2.96m / s.

[0009] Preferably, the step 102: cascade speed grouping. The rolling mills are grouped as “rough rolling 6 stands→intermediate rolling 6 stands→pre-finishing rolling 4 stands→finishing rolling 4 stands→reducing sizing unit”, the speeds of the stands in the same group are adjusted in linkage, and a speed buffer interval of 5%~8% is reserved between groups to avoid sudden tension changes between groups.

[0010] Preferably, the step 201: micro-tension control. In the rough rolling to pre-precision rolling interval (1~16 stands), micro tension rolling is adopted, and the tension state is judged through the current feedback of the stand: when the current fluctuation exceeds ±5%, the speed of the upstream stand is adjusted (±0.5%~1%), so as to ensure that the rolled piece is not obviously stretched or accumulated; The pre-precision rolling to precision rolling interval (17~20 stands) is provided with a vertical loop, and the loop height is controlled at 100~150mm. When the height deviation exceeds ±20mm, the speed of the upstream stand is adjusted (speed up if raised, and speed down if lowered), and the correction amount is ≤2%.

[0011] Preferably, the step 202 is speed synchronization correction. The red steel size of each stand is measured every hour, and when the size deviation of the rolled piece of a certain stand exceeds ±0.3mm, the speed of the stand and the adjacent upstream stand is adjusted (the speed correction is ±0.3% for each increase of 0.1mm of the deviation), so as to ensure that the size of the subsequent rolled piece returns to the standard range.

[0012] Preferably, the step 301 is stack steel / stretch steel treatment. When slight stack steel (rolled piece head accumulation) occurs, the speed of the downstream stand is immediately reduced by 10%~15%, and the speed of the upstream stand is increased by 5%~8% at the same time. After the rolled piece passes smoothly, the base speed is restored; When serious stretch steel (rolled piece tail thinning) occurs, the upstream stand is stopped, the corresponding flying shear is started to break, and after cleaning, the speed is reset to ensure that the speed of the first 3 rolled pieces is reduced by 5% after restarting.

[0013] Preferably, the step 302 is speed reset after roll replacement and groove replacement. After replacing the roll, the speed of the corresponding stand is corrected according to the new roll diameter (the speed is increased by 1%~1.5% for each reduction of 5mm of the roll diameter), and 1~2 trial rolled pieces are verified to ensure that the speed matches the speed of the upstream and downstream stands; When the groove is replaced, the corresponding speed parameters of the pass are updated at the same time, and the speed deviation of different grooves of the same stand is controlled within 3%.

[0014] Preferably, the step 401 is regular calibration. The speed sensor of each stand is calibrated once a day to ensure that the measurement error is ≤0.5%; and the speed cascade logic is checked every week to ensure that the response time of the speed linkage of the stands in the group is ≤0.5 seconds; According to the steel grade, the speed curve is adjusted: the low carbon steel adopts a higher speed (10~18m / s at the outlet of the precision rolling), and the high carbon steel adopts a lower speed (5~10m / s at the outlet of the precision rolling), so as to avoid overheat of the rolled piece or excessive rolling force.

[0015] Preferably, the step 402: data feedback optimization; The speed parameters, tension fluctuation and size deviation of each batch of rolled pieces are recorded, and when the size qualified rate of a certain specification product is less than 98%, the speed reference of the corresponding rack is re-optimized, and the adjustment range is less than or equal to 3%.

[0016] (Three) beneficial effects Compared with the prior art, the present application provides a multi-stand continuous rolling speed coordination control method for a bar rolling production line, which has the following beneficial effects: 1. The multi-stand continuous rolling speed coordination control method for the bar rolling production line improves rolling stability and reduces steel stacking and pulling accidents. Through the closed-loop control logic of "pre-rolling reference setting - dynamic adjustment during rolling", combined with cascading speed grouping (coarse rolling and intermediate rolling grouping linkage) and a 5%~8% speed buffer interval between groups, the speed ratio of adjacent stands and the elongation coefficient are accurately matched, the speed matching error is controlled within 1%, effectively solving the speed imbalance problem caused by traditional static setting due to roll wear (such as a 5mm reduction in roll diameter) and temperature fluctuations (±50℃), reducing the steel stacking and pulling accident rate by more than 60% in the coarse rolling to intermediate rolling and pre-precision rolling to precision rolling interval, ensuring a stable rolling rhythm of 150 square billets 40~50 seconds / branch, 162 circles 46~56 seconds / branch, and meeting the design requirement of an annual capacity of 600,000 tons.

[0017] 2. The multi-stand continuous rolling speed coordination control method for the bar rolling production line improves product size precision and ensures quality consistency. Dynamic speed correction (correction amount ≤2%) is implemented for loop height deviation (±20mm) and red steel size deviation (±0.3mm), combined with micro-tension control (speed adjustment when current fluctuation ±5%), so that the rolled piece is rolled in a tension-free or micro-tension state, the finished product diameter tolerance is stable within ±0.2mm, solving the size deviation problem caused by loop response lag in traditional control. At the same time, the speed curve is adjusted for different steel grades (low carbon steel precision rolling outlet 10~18m / s, high carbon steel 5~10m / s), which is suitable for controlled rolling and controlled cooling process, and meets the high-precision quality requirements of special steel and bearing steel.

[0018] 3、The bar rolling production line multi-stand continuous rolling speed coordination control method enhances the abnormal condition adaptability and reduces the scrap rate. After roll changing and groove changing, the speed is dynamically corrected according to the rule that the speed is increased by 1% to 1.5% for each 5mm reduction of the roll diameter, and the new roll is verified by trial pieces to ensure that the speed of the new roll matches the speed of the upstream and downstream stands, solving the size fluctuation problem caused by the change of the roll diameter. When the steel is stacked or drawn, the speed of the upstream and downstream stands is adjusted (for example, the speed of the downstream stand is reduced by 10% to 15% and the speed of the upstream stand is increased by 5% to 8% when the steel is slightly stacked), and the flying shear is broken, reducing the secondary failure and scrap production, and increasing the yield by 3% to 5%.

[0019] 4、The bar rolling production line multi-stand continuous rolling speed coordination control method optimizes the process adaptability and improves the production efficiency. The speed sensor is calibrated regularly (error ≤0.5%), the cascade logic is checked (response time ≤0.5 seconds), and the data feedback optimization is corrected when the qualified rate is less than 98%, so that the system continuously adapts to the rolling requirements of multiple steel types (gear steel, spring steel) and multiple specifications (Φ20-100mm), the single batch product debugging time is shortened by 10% to 15%, the rolling mill operation rate is increased by more than 5%, and the production efficiency and process flexibility are considered. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0021] Step 1: Speed reference setting before rolling; Step 101: Basic parameter confirmation; According to the rolling piece specifications (Φ20-100mm) and the design of each stand pass, the extension coefficient range of the rough rolling, intermediate rolling, pre-finishing rolling, finishing rolling and reducing sizing unit is determined: rough rolling 1.2-1.3, intermediate rolling 1.25-1.35, pre-finishing rolling 1.15-1.25, finishing rolling 1.1-1.2, and reducing sizing 1.05-1.15; Taking the finished product target speed as the reference (finishing rolling outlet speed 0.83-18m / s, adjusted according to the specifications), the theoretical speed of each stand is deduced in reverse order “finishing rolling→pre-finishing rolling→intermediate rolling→rough rolling”, ensuring that the speed ratio of adjacent stands matches the extension coefficient, the rough rolling inlet speed is controlled at 0.16-0.3m / s, the intermediate rolling inlet speed is 0.36-1.26m / s, and the pre-finishing rolling inlet speed is 0.9-2.96m / s; Step 102: Cascade speed grouping; The rolling mill is grouped as "rough rolling 6 stands → intermediate rolling 6 stands → pre-finishing rolling 4 stands → finishing rolling 4 stands → reducing sizing mill set", the speed of the stands in the same group is adjusted in linkage, a speed buffer interval of 5% to 8% is reserved between groups to avoid sudden change of tension between groups; Step 2: Dynamic adjustment of rolling process speed; Step 201: Micro-tension control; Micro-tension rolling is adopted in the interval from rough rolling to pre-finishing rolling (1-16 stands), and the tension state is judged through the current feedback of the stands: when the current fluctuation exceeds ±5%, the speed of the upstream stands is adjusted (±0.5% to 1%) to ensure that the rolled piece is not obviously stretched or accumulated; A looper is arranged in the interval from pre-finishing rolling to finishing rolling (17-20 stands), the height of the looper is controlled at 100-150 mm, and when the height deviation exceeds ±20 mm, the speed of the upstream stands is adjusted (speed is increased when the height is increased, and speed is decreased when the height is decreased), and the correction amount is ≤2%; Step 202: Speed synchronization correction; The red steel size of each stand is measured every hour, and when the size deviation of the rolled piece of a stand exceeds ±0.3 mm, the speed of the stand and the adjacent upstream stands is adjusted (the speed is corrected by ±0.3% for every increase of 0.1 mm of the deviation), to ensure that the size of the subsequent rolled piece returns to the standard range; Step 3: Cooperative response to abnormal conditions; Step 301: Treatment of accumulated steel / stretched steel; When slight accumulation of steel (accumulation of the head of the rolled piece) occurs, the speed of the downstream stands is immediately reduced by 10% to 15%, and the speed of the upstream stands is increased by 5% to 8%, and after the rolled piece passes smoothly, the base speed is restored; When serious stretching of steel (thinning of the tail of the rolled piece) occurs, the outfeed of the upstream stands is stopped, the corresponding flying shear is started to cut off (1# flying shear for rough rolling and 3# flying shear for finishing rolling), the speed is reset after cleaning to ensure that the speed of the first 3 rolled pieces is reduced by 5% after restarting; Step 302: Speed reset after roll change and groove change; After the roll is replaced, the speed of the corresponding stand is corrected according to the new roll diameter (the speed is increased by 1% to 1.5% for every 5 mm decrease in roll diameter), and the verification is performed through 1-2 trial rolled pieces to ensure that the speed matches the speed of the upstream and downstream stands; When the groove is changed, the speed parameters corresponding to the groove are updated simultaneously, and the speed deviation of different grooves of the same stand is controlled within 3%; Step 4: Speed stability maintenance; Step 401: Regular calibration; The speed sensor of each stand is calibrated once a day to ensure that the measurement error is ≤0.5%; the speed cascade logic is checked every week to ensure that the linkage response time of the stands in the same group is ≤0.5 seconds; Adjust the speed curve according to the steel grade: use a higher speed for low carbon steel (10~18m / s at the finish mill exit) and a lower speed for high carbon steel (5~10m / s at the finish mill exit) to avoid overheating of the workpiece or excessive rolling force; Step 402: Data feedback optimization; Record the speed parameters, tension fluctuations, and dimensional deviations of each batch of rolled pieces. When the dimensional pass rate of a certain specification of product is less than 98%, re-optimize the speed reference of the corresponding stand, with an adjustment range of ≤3%.

[0022] Furthermore, this method improves rolling stability and reduces steel piling and pulling accidents. Through the closed-loop control logic of "pre-rolling benchmark setting - dynamic adjustment during rolling", combined with cascaded speed grouping (coordinated grouping of roughing and intermediate rolling) and a speed buffer of 5%~8% between groups, the speed ratio of adjacent stands is precisely matched with the elongation coefficient, and the speed matching error is controlled within 1%. This effectively solves the speed imbalance problem caused by roll wear (such as a 5mm reduction in roll diameter) and temperature fluctuation (±50℃) in traditional static settings. The steel piling and pulling accident rate in the roughing to intermediate rolling and pre-finishing to finishing rolling intervals is reduced by more than 60%, ensuring a stable rolling rhythm of 40~50 seconds / piece for 150 square billets and 46~56 seconds / piece for 162 round billets, meeting the design requirements of an annual production capacity of 600,000 tons. Furthermore, this method improves product dimensional accuracy and ensures consistent quality. It implements dynamic speed correction (correction amount ≤2%) for looper height deviation (±20mm) and red steel dimensional deviation (±0.3mm), combined with micro-tension control (fine-tuning speed when current fluctuates ±5%), so that the rolled parts are rolled under no-tension or micro-tension conditions, and the finished product diameter tolerance is stabilized within ±0.2mm. This solves the problem of dimensional deviation caused by looper response lag in traditional control. At the same time, the speed curve is adjusted for different steel grades (10~18m / s at the finish rolling exit for low carbon steel, 5~10m / s for high carbon steel) to adapt to controlled rolling and controlled cooling processes and meet the high-precision quality requirements of alloy steel, bearing steel and special steel. Furthermore, this method enhances adaptability to abnormal operating conditions and reduces scrap rate. After changing rolls and grooves, the speed is dynamically corrected according to the rule of "a 1%~1.5% speed increase for every 5mm reduction in roll diameter," and verified by trial rolling pieces to ensure that the new roll matches the speed of the upstream and downstream stands, thus solving the problem of dimensional fluctuations caused by changes in roll diameter. When steel piling / pulling occurs, the upstream and downstream speeds are adjusted in tandem (e.g., a 10%~15% speed reduction downstream and a 5%~8% speed increase upstream in the case of slight steel piling) and combined with flying shear cutting to reduce secondary failures and scrap generation, increasing the yield by 3%~5%. Further, the method optimizes process adaptability and improves production efficiency. By regularly calibrating the speed sensor (error ≤0.5%), checking the cascade logic (response time ≤0.5 seconds), and optimizing data feedback (correcting the reference speed when the qualified rate is lower than 98%), the system continuously adapts to rolling requirements of multiple steel types (gear steel, spring steel) and multiple specifications (Φ20~100mm). The single batch product debugging time is shortened by 10%~15%, and the rolling mill operation rate is increased by more than 5%, balancing production efficiency and process flexibility.

[0023] In use, While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications, changes, omissions, substitutions, and equivalents can be made by one of ordinary skill in the art without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.

Claims

1. A method for coordinated speed control in multi-stand continuous rolling mills of bar rolling production lines, comprising step 1: setting the speed reference before rolling, step 2: dynamic speed adjustment during rolling, step 3: coordinated response to abnormal operating conditions, and step 4: speed stability maintenance, characterized in that: Step 1: Setting the speed reference before rolling includes step 101: confirming basic parameters and step 102: grouping cascaded speeds; Step 2: Dynamic speed adjustment during the rolling process includes step 201: micro-tension control and step 202: speed synchronization correction; Step 3: Collaborative Response to Abnormal Operating Conditions includes Step 301: Steel Stacking / Pulling Processing and Step 302: Speed ​​Reset After Roller and Groove Change; Step 4: Speed ​​stability maintenance includes step 401: Periodic calibration and step 402: Data feedback optimization.

2. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 101: Confirmation of basic parameters; Based on the specifications of the rolled pieces (Φ20~100mm) and the pass design of each stand, the elongation coefficient ranges for the roughing, intermediate, pre-finishing, finishing, and reducing sizing mills are determined as follows: roughing 1.2~1.3, intermediate 1.25~1.35, pre-finishing 1.15~1.25, finishing 1.1~1.2, and reducing sizing 1.05~1.

15. Based on the target speed of the finished product (finishing mill exit speed 0.83~18m / s, adjusted according to specifications), the theoretical speed of each stand is derived in reverse order of "finishing mill → pre-finishing mill → intermediate mill → roughing mill" to ensure that the speed ratio of adjacent stands matches the elongation coefficient. The entry speed of the roughing mill is controlled at 0.16~0.3m / s, the entry speed of the intermediate mill is 0.36~1.26m / s, and the entry speed of the pre-finishing mill is 0.9~2.96m / s.

3. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 102: Cascaded velocity grouping; The rolling mills are grouped into "6 roughing stands → 6 intermediate stands → 4 pre-finishing stands → 4 finishing stands → sizing mill". The speed of the stands within the same group is adjusted in a coordinated manner, and a speed buffer zone of 5% to 8% is reserved between groups to avoid sudden changes in tension between groups.

4. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 201: Micro-tension control; In the roughing to pre-finishing section (stands 1-16), micro-tension rolling is used. The tension status is judged by the stand current feedback: when the current fluctuation exceeds ±5%, the upstream stand speed is finely adjusted (±0.5%~1%) to ensure that the rolled piece has no obvious stretching or accumulation. A vertical looper is installed in the pre-finishing to finishing rolling section (stands 17-20). The looper height is controlled between 100 and 150 mm. If the height deviation exceeds ±20 mm, the speed of the upstream stand is adjusted (increase the speed if it is higher, and decrease the speed if it is lower). The correction amount is ≤2%.

5. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 202: Speed ​​synchronization correction; Measure the red steel dimensions of each stand every hour. When the dimensional deviation of the rolled piece on a certain stand exceeds ±0.3mm, adjust the speed of that stand and the upstream adjacent stand accordingly (for every 0.1mm increase in deviation, the speed is corrected by ±0.3%) to ensure that the dimensions of subsequent rolled pieces return to the standard range.

6. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 301: Steel stacking / pulling processing; If slight steel accumulation (piling up at the head of the rolled piece) occurs, immediately reduce the downstream stand speed by 10% to 15% and simultaneously increase the upstream stand speed by 5% to 8%. Once the rolled piece has passed smoothly, restore the reference speed. When severe steel pulling occurs (the tail of the rolled piece becomes thinner), stop the upstream stand from outputting steel, start the corresponding flying shear to break up the steel (use flying shear #1 for steel pile-up in roughing mill and flying shear #3 for steel pile-up in finishing mill), clean up the steel pile-up, reset the speed, and ensure that the speed of the first 3 rolled pieces is reduced by 5% after restarting for trial operation.

7. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 302: Reset the speed after changing the roller and groove; After replacing the rolls, adjust the corresponding stand speed according to the new roll diameter (increase the speed by 1%~1.5% for every 5mm reduction in roll diameter), and verify with 1~2 test rolls to ensure that it matches the speed of the upstream and downstream stands; When changing slots, the corresponding speed parameters of the hole type are updated synchronously, and the speed deviation of different slots on the same frame is controlled within 3%.

8. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 401: Periodic calibration; Each rack speed sensor is calibrated once daily to ensure measurement error ≤0.5%; the speed cascade logic is checked weekly to ensure rack speed linkage response time within the group ≤0.5 seconds. Adjust the speed curve according to the steel grade: use a higher speed for low carbon steel (10~18m / s at the finish mill exit) and a lower speed for high carbon steel (5~10m / s at the finish mill exit) to avoid overheating of the workpiece or excessive rolling force.

9. The method for coordinated control of multi-stand continuous rolling speed in a bar rolling production line according to claim 1, characterized in that: Step 402: Data feedback optimization; Record the speed parameters, tension fluctuations, and dimensional deviations of each batch of rolled pieces. When the dimensional pass rate of a certain specification of product is less than 98%, re-optimize the speed reference of the corresponding stand, with an adjustment range of ≤3%.