Method for rolling ultra-high strength steel using eighteen rollers

Abstract

The application relates to a method for rolling ultra-high-strength steel by using an 18-roller, which comprises the following steps: setting 18-roller working parameters; feeding the 18-roller; tracking the state of the ultra-high-strength steel and adjusting the real-time parameters of the 18-roller in real time; and receiving the output of the 18-roller. The method for rolling ultra-high-strength steel by using the 18-roller can realize stable operation of a production line, reduce fault time, improve the production capacity of the production line, reduce the number of quality degradation products, improve product quality, and enhance profitability.

Description

Technical Field

[0001] This application relates to the field of ultra-high strength steel, and more particularly to a method for rolling ultra-high strength steel using eighteen rolls. Background Technology

[0002] As a key profit-generating product for the company, ultra-high-strength steel requires a stable and controllable production process. With a monthly output of nearly 20,000 tons of cold-rolled ultra-high-strength steel, numerous defects such as waviness, thickness, and residue have occurred during the rolling process, resulting in a large number of downgraded products and cut losses, causing significant waste and posing a major threat to the stable production of ultra-high-strength steel. Summary of the Invention

[0003] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this application provides a method for rolling ultra-high strength steel using eighteen rolls.

[0004] In a first aspect, this application provides a method for rolling ultra-high-strength steel using an 18-roll mill, the method comprising the steps of:

[0005] Set the operating parameters for the 18 rollers;

[0006] Feed material into the eighteen rollers;

[0007] Track the condition of ultra-high strength steel and adjust the real-time parameters of the eighteen rollers in real time;

[0008] The ultra-high strength steel output from the eighteen rollers is received.

[0009] Preferably, setting the working parameters of the eighteen rollers includes the following steps:

[0010] Set the tilt value of the eighteen rollers;

[0011] Set the bending value of the eighteen rollers;

[0012] Set the roll shifting value of the eighteen rollers;

[0013] Set the tension value of the eighteen rollers.

[0014] Preferably, setting the tilt value of the eighteen rollers includes the following steps:

[0015] Obtain the actual value of the previous high-speed test;

[0016] Set the actual value of the previous high-speed test to the tilt value.

[0017] Preferably, setting the tilt value of the eighteen rollers includes the following steps:

[0018] Obtain the rolling force deviation value;

[0019] The value corresponding to when the rolling force deviation is close to zero is set as the tilt value.

[0020] Preferably, the rolling force deviation is within ±100 kN.

[0021] Preferably, setting the roll shifting value of the eighteen rolls includes the following steps:

[0022] Obtain the status of the shifting rollers;

[0023] The value of the upper and lower rollers is adjusted in real time to control the value of the upper and lower rollers within ±50mm.

[0024] Preferably, setting the tension value of the eighteen rollers includes the following steps:

[0025] Increase the unit tension at the first inlet pass;

[0026] Adjust the unit tension in the intermediate passes.

[0027] Preferably, adjusting the unit tension of the intermediate pass includes the following steps:

[0028] Obtain the unit tension at the exit and the unit tension at the entrance for the second to fourth passes;

[0029] Increase the difference between the unit tension at the outlet and the unit tension at the inlet.

[0030] Preferably, the difference between the unit tension at the outlet and the unit tension at the inlet is 30-60 MPa.

[0031] Preferably, the adjustment of the unit tension in the intermediate pass further includes the step of:

[0032] Reduce the unit tension at the exit of the fifth pass.

[0033] The technical solutions provided in this application have the following advantages compared with the prior art:

[0034] The method for producing ultra-high-strength steel using 18-roll mills provided in this application can achieve stable production line operation, reduce downtime, increase production line output, reduce the number of downgraded products, improve product quality, and enhance profitability. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart illustrating a method for rolling ultra-high-strength steel using 18-roll mills, as provided in an embodiment of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Figure 1 This is a schematic flowchart illustrating a method for rolling ultra-high-strength steel using 18-roll mills, as provided in an embodiment of this application.

[0040] This application provides a method for rolling ultra-high-strength steel using an 18-roll mill, the method comprising the following steps:

[0041] S1: Set the working parameters for the 18 rollers;

[0042] In this embodiment of the application, setting the working parameters of the eighteen rollers includes the following steps:

[0043] Set the tilt value of the eighteen rollers;

[0044] Set the bending value of the eighteen rollers;

[0045] Set the roll shifting value of the eighteen rollers;

[0046] Set the tension value of the eighteen rollers.

[0047] Specifically, the working parameters of the 18-roller system include: the tilt value, bending value, slippage value, and tension value of the 18-roller system.

[0048] In this embodiment of the application, setting the tilt value of the eighteen rollers includes the following steps:

[0049] Obtain the actual value of the previous high-speed test;

[0050] Set the actual value of the previous high-speed test to the tilt value.

[0051] In this embodiment of the application, setting the tilt value of the eighteen rollers includes the following steps:

[0052] Obtain the rolling force deviation value;

[0053] The value corresponding to when the rolling force deviation is close to zero is set as the tilt value.

[0054] In this embodiment of the application, the rolling force deviation value is within ±100kN.

[0055] Specifically, the tilt value needs to be adjusted before starting the machine. The tilt value can be adjusted to the actual value of the previous high-speed pass or the tilt value before starting the machine can be adjusted to a value where the rolling force deviation is close to zero. Before starting the machine, the rolling force deviation should be adjusted to within ±100kN.

[0056] In this embodiment, the bending roller value needs to be adjusted before starting the machine. For wide specifications, the IMR bending roller force should be appropriately reduced, and for narrow specifications, the bending roller force should be appropriately increased to ensure that the starting wave shape is a side wave mode and reduce the starting deviation. For thin-specification ultra-high strength steel (0.8mm), special attention should be paid to the starting plate shape. Ground personnel should pay attention to the plate shape at the roller gap before starting the machine. If any abnormality is found, the main operator should be reminded to stop the machine in time to avoid the accident from escalating.

[0057] In this embodiment of the application, setting the roll shifting value of the eighteen rolls includes the following steps:

[0058] Obtain the status of the shifting rollers;

[0059] The value of the upper and lower rollers is adjusted in real time to control the value of the upper and lower rollers within ±50mm.

[0060] Specifically, monitor the interface roller status in real time to ensure that the upper and lower roller shift values ​​are controlled within ±50mm.

[0061] In this embodiment of the application, setting the tension value of the eighteen rollers includes the following steps:

[0062] Increase the unit tension at the first inlet pass;

[0063] Adjust the unit tension in the intermediate passes.

[0064] In this embodiment of the application, adjusting the unit tension of the intermediate pass includes the following steps:

[0065] Obtain the unit tension at the exit and the unit tension at the entrance for the second to fourth passes;

[0066] Increase the difference between the unit tension at the outlet and the unit tension at the inlet.

[0067] In this embodiment of the application, the difference between the outlet unit tension and the inlet unit tension is 30-60 MPa.

[0068] In this embodiment of the application, the step of adjusting the unit tension of the intermediate pass further includes the following steps:

[0069] Reduce the unit tension at the exit of the fifth pass.

[0070] Specifically, regarding the tension settings for the 18-roll mill, the unit tension at the inlet of the first pass for thin specifications is appropriately increased to reduce start-up deviation. In the intermediate passes, the difference between the exit tension and the inlet tension is increased for passes 2-4, while the inlet tension is appropriately reduced and the exit tension is increased, with the unit exit tension exceeding the unit inlet tension by 30-60 MPa to increase forward slip and adapt to the high-speed rolling characteristics of the mill. The unit exit tension for the fifth pass for thin specifications is appropriately reduced to prevent start-up and edge breakage of the strip in the final pass.

[0071] S2: Feed material into the eighteen rollers;

[0072] S3: Track the state of ultra-high strength steel and adjust the real-time parameters of the eighteen rollers in real time;

[0073] S4: Receive the ultra-high strength steel output from the eighteen rollers.

[0074] Specifically, the steps for rolling ultra-high-strength steel using 18-roll mills are as follows:

[0075] Step 1: The 18-roller should be reviewed and approved, and the feeding standards should be strictly followed to ensure there are no obvious misalignments, tower-like shapes, or edge cracks.

[0076] Step 2: The crown is 0.02 to 0.08 mm, and the camber is no more than 10 mm in any 5 m section. The abnormal parts are rolled at a low speed, with a speed of <150 mp.

[0077] Step 3: Use new work rolls. Use narrow-gauge intermediate rolls for chamfering, 520+60mm chamfer.

[0078] Step 4: If the raw material has a poor shape and is prone to scratching the welding machine clamps, the uncoiling speed should be reduced. If the incoming material is flat and coiled, the uncoiling speed should not exceed 100mpm.

[0079] Step 5: Contact ground personnel in advance during the tail-swing process to monitor the rolling status on-site. The mill operator monitors the rolling force and tension deviations.

[0080] Step 6: Visible fuzz is present on the edge of the rolled strip, requiring rework and edge trimming.

[0081] The following is a more detailed description of a method for rolling ultra-high-strength steel using 18 rolls, as provided in this application.

[0082] The steps for controlling the cutting edge of raw materials in this application are as follows:

[0083] The rolling process for ultra-high strength steel is as follows: hot-rolled raw material coil - continuous pickling - single-stand rolling mill - post-processing line. Edge trimming is performed during the pickling process to remove areas with uneven grain distribution at the hot-rolled edges, effectively preventing edge cracking. Edge trimming of the raw material coil is also performed at the exit area of ​​the continuous pickling line to prevent edge cracking and strip breakage accidents caused by edge cracking during the rolling process. The edge trimming rules are as follows:

[0084] (1) Taking the mainstream DP steel product as an example, other steel grades are matched with steel grades with similar composition. Before production, an experiment is conducted. Starting with the maximum trimming amount, the amount is gradually reduced. The edge cracking situation after rolling is observed. If the crack depth does not exceed 2mm, it is considered qualified; otherwise, it is considered unqualified.

[0085] (2) The cutting blade hardness of the edge trimmer should be 58-60 HRC. If frequent blade breakage occurs, check whether the strip edge elevation and the working elevation of the edge trimmer are normal. Use a new cutting blade for the edge trimmer to reduce the use of repaired blades and avoid blade breakage caused by fatigue layer; change the secondary parameters, based on the original secondary parameters for ordinary high-strength steel, reduce the edge overlap by 10 lines under the original secondary parameters to effectively reduce the number of blade breakages. Before trimming high-strength high-carbon steel, use ordinary carbon steel or similar materials for hot cutting to improve the cutting blade. Modify the GAP / LAP setting value of the edge trimmer from the original 0.28 / 0.2 to 0.4 / -0.1. When using a new cutting blade, use fine sandpaper to grind the cutting blade to eliminate sharp surfaces and dull the cutting blade to avoid blade breakage. Control the exit speed to maintain uniform production as much as possible and avoid the impact of frequent speed increases and decreases on the cutting blade. When depressurizing and pressurizing, tighten and loosen the set screw evenly, turning it 2-3 turns each time. Depressurize until the pressure gauge no longer shows a red mark, and pressurize until the pressure gauge shows a red mark. After removing any lock nut, check if the inner steel ring has returned to the lock nut. If not, replace it with a new lock nut immediately. After each blade replacement, use a dial indicator. The radial direction should be within five marks, and the axial direction within two marks.

[0086] The steps for rolling control in this application are as follows:

[0087] (1) Flow rate per second: The thickness gauge data is pre-filled to the frame and from the frame to the outlet thickness gauge. The first and second passes use the set thickness value of the incoming material, and the subsequent passes use the recorded value of the outlet thickness gauge of the previous pass to reverse it. In this way, the flow rate per second function is put into use to quickly eliminate thickness difference.

[0088] (2) AGC Control: The 18-roll single-stand mill includes the following AGC functions: feedforward thickness control (FFC); feedback thickness control (FBC); flow rate thickness control (MFC); acceleration / deceleration compensation (ADC); and Bisra control (Bisra). After multiple tests, the AGC adopted Bisra (60%) + FF + FB for the first pass and FF + FB for passes 2-5, resulting in the smallest thickness difference at the exit of each pass and the smallest thickness difference of the finished product.

[0089] (3) Optimize the automatic gain coefficient of high-speed pressing control: An improved adjustment mechanism has been established that automatically outputs a percentage based on speed. The higher the speed, the lower the output percentage; the lower the speed, the higher the output percentage. This effectively reduces the drastic adjustment at high speeds, resulting in lower overshoot in pressing control, more stable system operation, and no thickness fluctuation exceeding tolerance. The gain coefficients are shown in the table below.

[0090]

[0091]

[0092] (4) Optimize the low-speed friction coefficient: In view of the situation that the rolling force of starting the machine is too small, resulting in a thicker difference between the head and tail, the low-speed friction coefficient is modified without affecting the friction coefficient calculated at high speed. The friction coefficient is optimized so that the friction coefficient below 30m / min is changed from 0.57 to 0.67 and the friction coefficient below 300m / min is changed from 0.27 to 0.276.

[0093] The steps for optimizing the rolling process in this application are as follows:

[0094] (1) Reduction rate:

[0095] 1) Ultra-high strength steel is prone to deviation. The reduction rate of No. 1 can be appropriately reduced, but it is necessary to ensure that the reduction rate of No. 1 frame is ≥ 75% of that of No. 2.

[0096] 2) The final reduction rate of ultra-high strength steel wool roll (Ra: 2.0μm) rolling is ≤3%, and the final reduction rate of smooth roll (Ra: 1.0μm) rolling is ≤5%. The final reduction rate can be appropriately reduced to improve the strip shape and ripples.

[0097] (2) Inclined:

[0098] Before starting the machine, the tilt value needs to be adjusted. The tilt value can be adjusted to the actual value of the previous high-speed pass, or the tilt value before starting the machine can be adjusted to a value where the rolling force deviation is close to zero. Before starting the machine, the rolling force deviation should be adjusted to within ±100kN.

[0099] (3) Bending roller:

[0100] 1) Before starting the machine, the bending roller value needs to be adjusted. For wide specifications, the IMR bending roller force should be appropriately reduced, and for narrow specifications, the bending roller force should be appropriately increased to ensure that the starting wave shape is the edge wave mode and reduce the starting deviation.

[0101] 2) Special attention should be paid to the shape of the plate when starting the machine for thin-gauge ultra-high-strength steel (0.8mm). Ground personnel should pay attention to the shape of the plate at the roll gap before starting the machine. If any abnormality is found, the main operator should be reminded to stop the machine in time to avoid the accident from escalating.

[0102] (4) Roller shifting:

[0103] Monitor the condition of the rollers and ensure that the vertical roller shift value is controlled within ±50mm.

[0104] The quality inspection steps in this application are as follows:

[0105] (1) Quality Inspection Requirements: Visual inspection after wiping with oiled paper or cloth. Use an oilstone for grinding; the grinding length in both the transverse and longitudinal directions must exceed 800mm, and the total grinding length must not be less than 1200mm. Each coil of steel must have its upper and lower surfaces wiped for quality inspection, and every two coils must be ground and inspected. Do not draw arcs during grinding. The upper surface should be inspected near the guide rollers, and the lower surface should be inspected in the coiler area. The inspection length should be ≥1.2m, and a strong flashlight should be used during the inspection.

[0106] (2) Dimensional Inspection: Inspection frequency: 2 times per coil, 1 time for top and bottom surfaces and strip edge cracks during roll change or the penultimate pass (if severe edge cracks are found, notify the mill to roll empty), and 1 time after the coil reaches the saddle. Edge cracks must be checked on each coil, strictly following the "SJTJS-LZ-JZ-High-Strength Steel Edge Crack Post-Curling Processing Line Online Standard Technical Notification Width Inspection Technical Notification," and the defect location and edge crack depth must be clearly noted in the quality judgment system. The inner ring of each coil must also be checked; any cracks found must be clearly noted and communicated to downstream processes.

[0107] (3) Thickness check: If the thickness exceeds the upper and lower limits of the planned cold-rolled coil thickness, no marking is required within the first and last 5 meters, but the rest must be marked in the system. Measure the actual thickness of every 3 rolls, check it against the thickness gauge, and record it in the system.

[0108] (4) Saddle position quality inspection: Inspection frequency: For cold-hardened finished products, wipe each roll with oil paper or cloth and inspect it. Every 2 rolls are polished with a steel oilstone and inspected.

[0109] (5) Appearance quality: Each roll of cold-rolled hardened coil is inspected after it comes off the production line. For example, edge cracks, burrs, edge waves, and tower shapes are not allowed. Edge threads, folds, loose coils and collapsed coils are not allowed. The system should mark the defects.

[0110] (6) Surface quality: After each cold-rolled coil comes off the line, check it. If there are scratches or roll marks on the inner and outer ring surfaces, immediately notify the main operator to stop the machine for inspection. Check the surface of the strip at the mill entrance and exit. If necessary, perform a roll pull inspection to confirm whether there are any problems with the equipment or the rolls.

[0111] (7) Shutdown Inspection: Implement the first coil shutdown inspection system: • The first coil after maintenance, the first coil after a rolling accident, and the quality inspection after the mill has rolled 50 meters. Under normal circumstances, the quality of the exit strip is inspected during the penultimate rolling pass; each shift selects 2 coils of strip with a thickness tolerance >30μm, and stops to inspect them after rolling 40 meters in the last pass (once at the start of the shift and once during the shift) to avoid batch quality accidents in the strip. If there are abnormalities in the quality of cold-rolled coils, they can be inspected after each pass; when the shift team produces a batch (≥5 coils) of defective coils or when the post-processing line reports a batch (≥5 coils) of defective coils confirmed by the 18-roll mill, the work area is notified and the shift dispatcher is notified in a timely manner.

[0112] (8) Blind Spot Inspection: After taking over the shift, assign a dedicated person to inspect the inlet and outlet saddles of the rolling mill to prevent foreign objects from causing mass damage. For every 5 coils of steel, inspect at low speed (≤100mpm) once, including pinch rolls, straightening mill, steering rolls, squeezing rolls, brake rolls, etc., and take photos to report to the inspection group. Before scheduled maintenance or restarting after a long-term shutdown, inspect all saddles in the shuttle car area and rolling mill area to confirm that there are no foreign objects on the saddles. Quality Coordination: Based on the quality feedback from the post-processing line, immediately organize the work team to check the quality situation and identify any corresponding defects.

[0113] The method for producing ultra-high-strength steel using 18-roll mills provided in this application can achieve stable production line operation, reduce downtime, increase production line output, reduce the number of downgraded products, improve product quality, and enhance profitability.

[0114] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0115] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for rolling ultra-high strength steel using eighteen rolls, characterized in that, The method comprises steps of: setting eighteen-roller working parameters; feeding into the eighteen-roller; tracking ultra-high strength steel status and adjusting eighteen-roller real-time parameters in real time; receiving the ultra-high strength steel output by the eighteen-roller; the setting eighteen-roller working parameters comprises steps of: setting the inclination value of the eighteen-roller; obtaining the last pass high-speed actual value, setting the last pass high-speed actual value as the inclination value; or, obtaining the rolling force deviation value, setting the value corresponding to the time when the rolling force deviation value is close to zero as the inclination value; setting the bending roller value of the eighteen-roller: before starting, reducing IMR bending roller force for wide specifications and increasing bending roller force for narrow specifications to ensure that the starting wave shape is in the edge wave mode; setting the roll shifting value of the eighteen-roller: obtaining the roll shifting state, adjusting the roll shifting value in real time to control the up and down roll shifting values to within ±50mm; setting the tension value of the eighteen-roller: increasing the first pass inlet unit tension, adjusting the intermediate pass unit tension: obtaining the outlet unit tension and the inlet unit tension of the second pass to the fourth pass, increasing the difference between the outlet unit tension and the inlet unit tension, and reducing the outlet unit tension of the fifth pass; the difference between the outlet unit tension and the inlet unit tension is 30-60Mpa.

2. The method for producing ultra-high strength steel using eighteen-roller rolling according to claim 1, characterized in that, The rolling force deviation value is within ±100kn.

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