Rolling method for controlling negative deviation of bar stock
By adjusting temperature, tension, and linear deviation, the problem of inaccurate negative deviation control during bar rolling was solved, effectively reducing negative deviation and lowering production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SGIS SONGSHAN CO LTD
- Filing Date
- 2023-05-24
- Publication Date
- 2026-06-30
Smart Images
Figure CN116550749B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rebar cutting and rolling technology, and more specifically, to a rolling method for controlling negative deviations in bar stock. Background Technology
[0002] During the bar rolling process, the small head and large tail of the finished product will inevitably limit the control range of negative deviation. When sampling, the head is not flattened after being cut with a cutting torch and the weight is directly weighed and calculated, which can easily lead to inaccurate negative deviation calculation. During the period of bar delivery based on theoretical weight, this negative deviation control method has little impact on cost. Starting from January 1, 2023, the Guangdong Provincial Building Materials Market began to implement the theoretical weight delivery model. Under the theoretical weight delivery model, this will greatly increase production costs and cause material waste.
[0003] Therefore, minimizing negative deviations is particularly important for rebar rolling. In view of this, the present invention is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide a rolling method for controlling the negative deviation of bar stock and reducing the negative deviation.
[0005] This invention is implemented as follows:
[0006] In a first aspect, the present invention provides a rolling method for controlling negative deviation of bar stock, comprising:
[0007] Temperature regulation: during the roughing, intermediate rolling and finishing rolling processes, the temperature at the head of the billet is 25-35°C higher than the temperature at the middle of the billet, and the temperature at the tail of the billet is 30-50°C higher than the temperature at the middle of the billet.
[0008] Tension adjustment: the tension is adjusted to no tension or micro-pilling rolling in the roughing mill, micro-tension rolling in the intermediate mill, and the finishing mill looper is automatically adjusted to no tension; wherein, for two adjacent mills, the micro-pilling rolling means that the negative deviation of the current or torque of the subsequent mill compared with the current or torque of the preceding mill is 0-2%, and the micro-tension rolling means that the positive deviation of the current or torque of the subsequent mill compared with the current or torque of the preceding mill is 0-2%;
[0009] Adjust the line difference by leveling the pre-cutting slit of the K4 rolling mill and aligning its centerline with the centerline of the billet, so that the billets passing through the side grooves are of the same length after entering the cooling bed. Then adjust the K4 rolling mill and the preceding rolling mills to make the billets passing through the middle groove and the billets passing through the side grooves of the K4 rolling mill have the same length after entering the cooling bed.
[0010] In an alternative implementation, for the same rolling mill, if the billet temperature increases, the tension is reduced; if the temperature decreases, the tension is increased.
[0011] In an optional implementation, the speed ratio of each rolling mill is adjusted in reverse mode during the tension adjustment step.
[0012] In an optional implementation, during the tension adjustment step, when adjusting the mill speed, the exit line speed of the last mill is used as the reference for speed adjustment. When adjusting the speed of any mill, the speed coordination relationship between other adjacent mills in the entire range remains unchanged.
[0013] In an optional embodiment, in the finishing rolling step, a front pressure roller, a starting roller, and a rear pressure roller are sequentially arranged between two adjacent rolling mills along the rolling direction, and a looper height detection device is provided between the starting roller and the rear pressure roller.
[0014] In an optional implementation, when the looper height detection device detects that the looper height is greater than a preset range, the main drive motors of each rolling mill upstream of the looper are cascaded down; when the looper height detection device detects that the looper height is less than the preset range, the motors of each rolling mill upstream are cascaded up until the looper height detection device detects that the looper height is within the preset range.
[0015] In an optional implementation, if the size of the lug exceeds a preset value when the billet passes through the mill pass, the severely worn pass is replaced.
[0016] In an optional embodiment, the steel billet is subjected to roughing, intermediate rolling, and finishing rolling in sequence during the rolling process. The steel billet in the roughing step passes through 6 rolling mills in sequence, numbered 1#, 2#, 3#, 4#, 5#, and 6#. The steel billet in the intermediate rolling step passes through 4 rolling mills in sequence, numbered 7#, 8#, 9#, and 10#. The steel billet in the finishing rolling step passes through 8 rolling mills in sequence, numbered 11#, 12#, 13#, 14#, 15#, 16#, 17#, and 18#. The K4 rolling mill is the 15# rolling mill.
[0017] In an optional implementation, when the line difference is unstable, at least one of the following methods is used to adjust the line difference:
[0018] ① Adjust the clamping relationship between the guides and the workpiece at the inlet of the pre-splitting pass rolling mill and the split pass rolling mill;
[0019] ②If the billets after passing through the intermediate rolling mill are irregular, the round material has misaligned holes, the hole is not fully filled, the tension is too high, or the filling degree of the hole at the beginning and end of the same billet fluctuates greatly, then replace the rolls of the rolling mill.
[0020] ③ If the filling degree of the pre-cut hole of the rolling mill is less than the preset value, adjust the shape of the billet or replace the worn pre-cut hole of the rolling mill;
[0021] ④ Due to the large differences in the head of the material, reduce the rolling tension or reduce the billet temperature rise.
[0022] ⑤ The roll gap deviation between No. 17 and No. 18 rolling mills is less than 0.1 mm.
[0023] In an optional implementation, the bar is cut using a grinding wheel during sampling, with the cut perpendicular to the bar's axis.
[0024] The present invention has the following beneficial effects:
[0025] This application controls the negative deviation of the bar stock by adjusting three aspects: temperature, tension, and linear difference, which can effectively reduce the negative deviation. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic diagram of a loop structure.
[0028] Diagram: 1-Starting roller; 2-Front pressure roller; 3-Rear pressure roller. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0030] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0031] Some embodiments of the present invention provide a rolling method for controlling negative deviation of bar stock, comprising:
[0032] Temperature regulation: during the roughing, intermediate rolling and finishing rolling processes, the temperature at the head of the billet is 25-35°C higher than the temperature at the middle of the billet, and the temperature at the tail of the billet is 30-50°C higher than the temperature at the middle of the billet.
[0033] Tension adjustment: the tension is adjusted to no tension or micro-pilling rolling in the roughing mill, micro-tension rolling in the intermediate mill, and the finishing mill looper is automatically adjusted to no tension; wherein, for two adjacent mills, the micro-pilling rolling means that the negative deviation of the current or torque of the subsequent mill compared with the current or torque of the preceding mill is 0-2%, for example, 0, 0.5%, 1%, 1.5%, or 2%, and the micro-tension rolling means that the positive deviation of the current or torque of the subsequent mill compared with the current or torque of the preceding mill is 0-2%, for example, 0, 0.5%, 1%, 1.5%, or 2%.
[0034] Adjust the line difference by leveling the pre-cutting slit of the K4 rolling mill and aligning its centerline with the centerline of the billet, so that the billets passing through the side grooves are of the same length after entering the cooling bed. Then adjust the K4 rolling mill and the preceding rolling mills to make the billets passing through the middle groove and the billets passing through the side grooves of the K4 rolling mill have the same length after entering the cooling bed.
[0035] Regarding the rolling process temperature, to overcome the "small head, large tail" temperature caused by tension, the ideal steel temperature is: the temperature of the billet head (30-50cm) is 25-35℃ higher than the middle temperature, and the temperature of the tail (30-50cm) is 30-50℃ higher than the middle temperature. The middle temperature should be relatively uniform, and the temperature at the junction of the middle and the head and tail should change slowly. Specifically, during temperature control, while ensuring the billet meets the above conditions, it is also necessary to maintain stable production throughout the rolling line as much as possible, including minimizing temperature deviations between batches of billets and avoiding billets waiting outside the furnace. When rolling cold billets, the billet spends a relatively longer time in the furnace than hot billets. Therefore, when it is anticipated that cold billets will be rolled, the production speed can be reduced in advance to allow the cold billet temperature to reach the same level as the hot billet. When adjusting the production rhythm, the operators at the front should be notified in advance to facilitate their operation and sampling, especially when the production rhythm is accelerated, allowing them sufficient time to operate.
[0036] For tension control during the rolling process, the roughing and intermediate rolling tension adjustment employs a current (torque) memory method: When a steel piece bites into the nth stand of the rolling mill, after the motor's dynamic speed reduction recovers, the current is measured until the piece bites into the (n+1)th stand. For the nth stand, this is equivalent to free rolling without pre-tension; the filtered and sampled rolling current at this time is considered the free rolling current. When the steel piece bites into the (n+1)th stand and the dynamic speed reduction recovers, the current is sampled again after filtering. If there is a tension deviation between the two mills, there will inevitably be a current deviation. According to relevant formulas in electrical engineering, the tension difference can be obtained. Based on the tension deviation, the speed is adjusted, regulating the speed of the nth stand and preceding stands to achieve a micro-tension or micro-bulk state. This process is continuously adjusted sequentially according to the billet's forward movement, until all mills with micro-tension closed-loop control achieve a micro-tension state, and all mills with micro-bulk closed-loop control achieve a micro-bulk state, thus achieving automatic tension adjustment.
[0037] For line difference adjustment, first fine-tune the horizontal centering of the K4 pre-cutting inlet to make the length of the upper cooling bed of the two side grooves consistent. The actual starting height of the side grooves of the 6# looper (the looper closest to the last rolling mill) can be used as a reference to ensure that the pre-cutting material is symmetrically filled. When the lengths of the two side lines are basically consistent, adjust the size and length difference between the middle groove and the side groove by adjusting K4 and the material type of the previous pass. The presence of tension will shorten the two side grooves. When the tension of the rolling line is large, the tension can be manually adjusted by the main operator to lengthen the two side grooves.
[0038] In an alternative implementation, for the same rolling mill, if the billet temperature increases, the tension is reduced; if the temperature decreases, the tension is increased.
[0039] The operator must adjust the tension in a timely manner according to the temperature change. If the billet is rolled from cold billet to hot billet, the tension needs to be reduced. If the billet is rolled from hot billet to cold billet, the tension needs to be increased. If the tension cannot keep up, it may suddenly cause a large number of products that do not meet the national standards.
[0040] In an optional implementation, the speed ratio of each rolling mill is adjusted in reverse mode during the tension adjustment step.
[0041] To ensure stable rolling on the rolling line, a certain continuous rolling speed relationship must be maintained between all rolling mills. Using speed cascade adjustment and control can ensure the speed ratio relationship of each rolling mill during the rolling process.
[0042] In an optional implementation, during the tension adjustment step, when adjusting the mill speed, the exit line speed of the last mill is used as the reference for speed adjustment. When adjusting the speed of any mill, the speed coordination relationship between other adjacent mills in the entire range remains unchanged.
[0043] When adjusting the mill speed, the finished mill is always used as the reference mill for speed adjustment. The basic principles for setting the mill line speed are: a. When the manual speed adjustment mode is "cascaded", adjusting the speed of any mill will not affect the speed coordination between any other mills within the entire line. b. The speed of the entire line is determined by a single variable: the final mill exit speed.
[0044] In an optional embodiment, during the finishing rolling step, a front pressure roller 2, a starting roller 1, and a rear pressure roller 3 are sequentially arranged along the rolling direction between two adjacent rolling mills. A looper height detection device is installed between the starting roller 1 and the rear pressure roller 3. Figure 1 As shown.
[0045] In an optional implementation, when the looper height detection device detects that the looper height is greater than a preset range, the main drive motors of each rolling mill upstream of the looper are cascaded down; when the looper height detection device detects that the looper height is less than the preset range, the motors of each rolling mill upstream are cascaded up until the looper height detection device detects that the looper height is within the preset range.
[0046] Looping occurs when excess length of rolled stock is stored between rolling mills. This excess stock effectively buffers against stock accumulation, preventing steel buildup in continuous steel rolling lines and ensuring finished product quality. Controlling the tension in the finishing rolling process, using the looping length as the target and speed adjustment as the means, achieves looping control. Specifically, each loop is equipped with a looping height detector to detect the actual looping height and compare it with a set value. When the actual looping height is greater than the set value, the main drive motors of the upstream rolling mills cascade down; when the actual looping height is less than the set value, the upstream rolling mill motors cascade up until the looping height is controlled within the set range, then the normal rolling speed is restored. During looping control, the speed adjustment of the upstream rolling mills can be achieved through a cascaded control system. The adjusted and stabilized looping speed value should be stored as the set value for the next steel strip.
[0047] The control process of looper includes taking off the looper, measuring the looper value, and dropping the looper.
[0048] Looping: After the head of the rolled piece triggers the loop scanner between the two rolling mills to form a loop, a looping signal can be given after a delay, and the looping wheel 1 will move. At the same time, it is important to ensure that the downstream rolling piece runs at a speed slightly lower than the set speed so as to quickly form a loop.
[0049] The measurement value of the looper is set to H2 (mm). When the looper scanner detects a height value of H1, the looper is under significant tension. The looper control system then instructs the upstream mill to increase its speed in a cascading manner. When the height value of H3 is detected, the looper is in a state of excessive steel accumulation. The looper control system then instructs the upstream mill to decrease its speed in a cascading manner, eventually stabilizing the looper measurement at the design value.
[0050] Dropping the looper: When the hot metal detector or looper scanner in front of the upstream mill of the looper sends a no-steel signal, the upstream mill of the looper runs at a speed lower than the rolling speed. When the tail of the rolled piece leaves the mill in front of the looper, the looper height is reduced to the minimum, the looper roller 1 drops after a delay, and the mill returns to the set speed to complete the looping process.
[0051] In an optional implementation, if the size of the lug exceeds a preset value when the billet passes through the mill pass, the severely worn pass is replaced.
[0052] Fine-tuning the tension requires coordination between the main operator and the ground crew. The material profile must be carefully controlled to prevent overfilling of the pass and the formation of large burrs. In areas where stands are too far apart or where there are no loopers, the main operator may have difficulty controlling the process and on-site personnel are needed to direct adjustments. Furthermore, severe wear on the mill passes can lead to large burrs at the tail end, requiring timely replacement, especially in the 17# mill pass, the 13# mill pre-cutting pass, and the 14# mill slitting pass. Ensure uniform steel temperature, prevent "steel backflow" in each pass, and avoid the formation of large burrs in each pass.
[0053] In an optional embodiment, the steel billet is subjected to roughing, intermediate rolling, and finishing rolling in sequence during the rolling process. The steel billet in the roughing step passes through 6 rolling mills in sequence, numbered 1#, 2#, 3#, 4#, 5#, and 6#. The steel billet in the intermediate rolling step passes through 4 rolling mills in sequence, numbered 7#, 8#, 9#, and 10#. The steel billet in the finishing rolling step passes through 8 rolling mills in sequence, numbered 11#, 12#, 13#, 14#, 15#, 16#, 17#, and 18#. The K4 rolling mill is the 15# rolling mill.
[0054] In an optional implementation, when the line difference is unstable, at least one of the following methods is used to adjust the line difference:
[0055] ① Adjust the clamping relationship between the guides and the workpiece at the inlet of the pre-splitting pass rolling mill and the split pass rolling mill;
[0056] ②If the billets after passing through the intermediate rolling mill are irregular, the round material has misaligned holes, the hole is not fully filled, the tension is too high, or the filling degree of the hole at the beginning and end of the same billet fluctuates greatly, then replace the rolls of the rolling mill.
[0057] ③ If the filling degree of the pre-cut hole of the rolling mill is less than the preset value, adjust the shape of the billet or replace the worn pre-cut hole of the rolling mill;
[0058] ④ Due to the large differences in the head of the material, reduce the rolling tension or reduce the billet temperature rise.
[0059] ⑤ The roll gap deviation between No. 17 and No. 18 rolling mills is less than 0.1 mm.
[0060] In an optional implementation, the bar is cut using a grinding wheel during sampling, with the cut perpendicular to the bar's axis.
[0061] After the bar stock is precision rolled, it is sampled. The sampling process must be standardized, and the sampling length must be greater than 500mm. The cut surface must be strictly ground flat during sampling. Hydraulic shears and flame cutting cannot produce a flat cut surface. A grinding wheel must be used to cut the bar, and the cut must be perpendicular to ensure a flat cut surface.
[0062] In addition, in order to accurately control the fixed length, it is necessary to explore the amount of cold shrinkage of the length of the bar after cutting for each specification, and guide the production team to control the fixed length during the production process; at the same time, during the production process, each shift measures and monitors the fixed length of cold and hot steel every 2 hours, which helps to improve the accuracy of the fixed length.
[0063] The previous rolling method was improved by focusing on increasing the billet temperature and reducing the mill motor current for temperature control. Tension adjustment was used to ensure production stability through steel pulling and rolling. However, this resulted in a small head and large tail, inaccurate line difference control, and long adjustment time with poor results. When sampling, the head of the sample was not flattened after being cut with a cutting torch before weighing and calculation, leading to inaccurate negative difference calculation. During the bar delivery period, this negative difference control method had little impact on cost, but during the theoretical delivery period, it would greatly increase production costs and cause material waste.
[0064] This application controls the negative deviation of the bar stock by controlling three aspects: temperature, tension, and linear difference. Compared with the previous rolling method, it can effectively reduce the negative deviation, improving the negative deviation from an average of -3.7% per month to -3.9%, and improving the negative deviation control level by more than 5%.
[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A rolling method for controlling negative deviation of bar stock, characterized in that, include: Temperature regulation: During roughing, intermediate rolling and finishing rolling, the temperature at the head of the billet is 25-35℃ higher than the temperature in the middle of the billet, and the temperature at the tail of the billet is 30-50℃ higher than the temperature in the middle of the billet; Tension adjustment: the tension is adjusted to no tension or micro-pilling in the roughing mill, micro-tension rolling in the intermediate mill, and the finishing mill looper is automatically adjusted to no tension; wherein, for two adjacent mills, micro-pilling rolling means that the negative deviation of the current or torque of the subsequent mill compared to the current or torque of the preceding mill is 0-2%, and micro-tension rolling means that the positive deviation of the current or torque of the subsequent mill compared to the current or torque of the preceding mill is 0-2%; Line difference adjustment: Adjust the pre-cutting slit of K4 mill to be horizontal and the center line to coincide with the center line of billet, so that the length of billet after passing through the side grooves on both sides is consistent after entering the cooling bed. Then adjust K4 mill and the preceding mills to make the length of billet after passing through the middle groove consistent with that of billet after passing through the side grooves on both sides after entering the cooling bed. For the same rolling mill, if the billet temperature rises, the tension is reduced; if the temperature falls, the tension is increased.
2. The rolling method for controlling negative deviation of bar stock according to claim 1, characterized in that, In the tension adjustment step, the speed ratio of each rolling mill is adjusted using a reverse adjustment mode.
3. The rolling method for controlling negative deviation of bar stock according to claim 2, characterized in that, In the tension adjustment step, when adjusting the mill speed, the exit line speed of the last mill is used as the reference for speed adjustment. When adjusting the speed of any mill, the speed coordination relationship between other adjacent mills in the entire range remains unchanged.
4. The rolling method for controlling negative deviation of bar stock according to claim 1, characterized in that, In the finishing rolling step, a front pressure roller, a starting roller, and a rear pressure roller are sequentially arranged between two adjacent rolling mills along the rolling direction, and a looper height detection device is installed between the starting roller and the rear pressure roller.
5. The rolling method for controlling negative deviation of bar stock according to claim 4, characterized in that, When the looper height detection device detects that the looper height is greater than the preset range, it causes the main drive motors of each rolling mill upstream of the looper to slow down in cascade; when the looper height detection device detects that the looper height is less than the preset range, it causes the motors of each rolling mill upstream to speed up in cascade until the looper height detection device detects that the looper height is within the preset range.
6. The rolling method for controlling negative deviation of bar stock according to claim 1, characterized in that, If the size of the lugs exceeds the preset value when the billet passes through the rolling mill pass, the severely worn pass should be replaced.
7. The rolling method for controlling negative deviation of bar stock according to claim 1, characterized in that, During the rolling process, the steel billet sequentially passes through roughing, intermediate rolling, and finishing rolling. In the roughing step, the steel billet passes through 6 rolling mills, numbered 1#, 2#, 3#, 4#, 5#, and 6# in sequence. In the intermediate rolling step, the steel billet passes through 4 rolling mills, numbered 7#, 8#, 9#, and 10# in sequence. In the finishing rolling step, the steel billet passes through 8 rolling mills, numbered 11#, 12#, 13#, 14#, 15#, 16#, 17#, and 18# in sequence. The K4 rolling mill is the 15# rolling mill.
8. The rolling method for controlling negative deviation of bar stock according to claim 7, characterized in that, When the line difference is unstable, adjust the line difference using at least one of the following methods: ① Adjust the clamping relationship between the guides and the workpiece at the inlet of the pre-splitting pass rolling mill and the split pass rolling mill; ②If the billets after passing through the intermediate rolling mill are irregular, the round material has misaligned holes, the hole is not fully filled, the tension is too high, or the filling degree of the hole at the beginning and end of the same billet fluctuates greatly, then replace the rolls of the rolling mill. ③ If the filling degree of the pre-cut hole of the rolling mill is less than the preset value, adjust the shape of the billet or replace the worn pre-cut hole of the rolling mill; ④ Due to the large differences in the head of the material, reduce the rolling tension or reduce the billet temperature rise. ⑤ The roll gap deviation between No. 17 and No. 18 rolling mills is less than 0.1 mm.
9. The rolling method for controlling negative deviation of bar stock according to claim 1, characterized in that, During sampling, the bar was cut using a grinding wheel, with the cut perpendicular to the bar's axis.