A hot rolling rough rolling method for a strip steel with large temperature fluctuation

Abstract

The application relates to a hot rolling rough rolling method of strip steel with large temperature fluctuation, which comprises the following steps: S1, swinging device and logic control during rough rolling temperature drop; S2, realization of new product rolling strategy in a rough rolling model; and S3, control of speed between rough rolling outlet and hot coil box inlet; the technical scheme ensures realization of the rolling specification strategy and temperature control of the strip steel, and ensures that the internal structure of the rough rolling area does not change.

Description

TECHNICAL FIELD

[0001] The present application relates to a rolling method, in particular to a hot rough rolling method of a strip steel with large temperature fluctuation, and belongs to the technical field of production control of hot rough rolling. BACKGROUND

[0002] With the requirements of domestic steel market, the requirements of hot rolling production strip steel are higher and higher, and the development of new product rolling has become an irresistible trend. The characteristics of the new product rolling in the present technology are that the temperature fluctuation is large, and the temperature sensitivity of each region is high. The 1422 hot rolling production line of Meisteel needs to develop a set of rolling method suitable for the new product according to the existing rolling equipment and capacity, considering the characteristics of model, process and equipment, and meet the needs of new product rolling. SUMMARY

[0003] The present application is just for the problems existing in the prior art, and provides a hot rough rolling method of a strip steel with large temperature fluctuation. The technical scheme not only ensures the realization of rolling specification strategy, but also ensures the temperature control of the strip steel, and ensures that the internal structure of the rough rolling area will not change.

[0004] In order to achieve the above purpose, the technical scheme of the present application is as follows, a hot rough rolling method of a strip steel with large temperature fluctuation, characterized in that the method comprises the following steps:

[0005] S1, swinging device and logic control during rough rolling temperature drop;

[0006] S2, realization of new product rolling strategy in rough rolling model;

[0007] S3, control of speed between rough rolling outlet and hot coil box inlet.

[0008] As an improvement of the present application, step S1, swinging device and logic control during rough rolling temperature drop, is as follows:

[0009] Since the temperature needs to be reduced by 210 DEG C in the rough rolling area, and the rough rolling area is not affected, in order to realize this product requirement, the temperature needs to be reduced after the last rough rolling mill is rolled, so various factors such as strip specification, on-site equipment arrangement, temperature drop time need to be considered.

[0010] S11, determination of swinging position, the strip steel needs to be cooled by 210 DEG C, and the strip steel has completed the rough rolling at this time, so the length of the strip steel has reached the length of the hot rolling intermediate billet;

[0011] Length calculation formula: Len = (slab original length x slab thickness x slab width) / (strip intermediate billet thickness x strip rough rolling outlet target width)

[0012] According to the product variety of Meigang hot rolling, the length of the strip after rough rolling is calculated to be up to 51m, and the length from the rough rolling exit to the fine rolling entrance is only 60m. When the strip swings, the strip will rush into the rack due to inertia, causing scrap. It is calculated that the length of the roller way between R1 and R2 is 100m, which meets the swing requirement, so the swing position of the strip is placed here.

[0013] S12, swing logic implementation, after the swing position of the strip is determined, in order to realize swing cooling, the strip needs to be forced to stop and enter the swing. The swing function of Meigang hot rolling is still used for emergency treatment when production problems occur, so the swing function can be started only after the strip stops for 30s. When new products are rolled, the second rack R2 of the rough rolling equipment is not allowed to enter the steel, which prevents the strip from rolling the last pass of R2. After 30s, the swing cooling function is automatically started;

[0014] S13, determination of the starting point of the swing, in order to protect the on-site equipment and prevent the strip from rushing into the rack equipment due to inertia, the starting point of the swing is moved to the middle, and the starting point is determined as the front group of the strip distribution roller way, and the ending position is determined as the position 1m away from the front of R2 rolling mill.

[0015] As an improvement of the present application, S2, realization of new product rolling strategy in the rough rolling model; specifically as follows:

[0016] In order to make up for the defect of insufficient roller way length, the swing position is moved forward to the last pass before R2. After the swing, the temperature has been reduced to the temperature of the fine rolling entrance, which cannot meet the requirements of the last pass rolling, so the last pass needs to be skipped. In order to meet the requirements of product rolling specifications and rolling mill load, the rolling strategy of the rough rolling mill needs to be adjusted.

[0017] S21, determination of the rough rolling rolling strategy, in order to ensure that the last pass is skipped and the load of each pass is not over limited, the original rough rolling rolling strategy is changed from 1+5 rolling mode to 1+7 rolling, and the 7 passes are skipped, that is, equivalent to 1+6 rolling;

[0018] S22, realization of the rolling strategy, in order to realize the 1+6 rolling method, the control logic of the equipment and the model needs to be completed,

[0019] Firstly, on the equipment, since the last pass is empty, and the strip is being rolled on the reverse pass, when the temperature drops to the target temperature, the strip needs to be moved to the next process for rolling in time. In the normal mode, the strip enters the next time sequence, which needs to collect signals on the spot, that is, the last pass of the R2 rolling mill is used to judge the position and move the strip by using the rolling force. In the empty mode, the equipment roll gap is raised, and there is no rolling force, so a steel biting and throwing signal of the rolling mill needs to be artificially synthesized. In this technical solution, the steel biting and throwing signal of the rolling mill is simulated by the on-site thermal sensor signal and the strip head and tail position information calculated according to the roll speed and time.

[0020] Secondly, in the model setting, the 1+6 rolling mode needs to consider the redistribution of the load and the setting of the rough rolling target width and thickness. When rolling for 6 passes, the last pass of the strip is reverse rolling, and the edger roller is empty. Therefore, the width reduction control (i.e. edger rolling) is only for 5 passes of rolling, while the thickness control (i.e. horizontal roller rolling) is for 6 passes of rolling. When setting the parameters, the edger parameters need to be configured and calculated according to the 5-pass rolling mode, and the horizontal roller parameters need to be configured and calculated according to the 6-pass rolling mode. When setting the model, the rough rolling target width is reached at the fifth pass, and the rough rolling thickness target is reached at the sixth pass.

[0021] S23, the implementation of the descaling code, in order to rapidly cool down, the descaling water between the stands is fully opened,

[0022] S24, protection of the R2 post-process equipment, in order to ensure that the post-process equipment will not be damaged due to errors in this process, the roll gap deviation protection is added, which generally refers to the deviation between the actual lifting of the roll gap and the model setting thickness.

[0023] As an improvement of the present application, step S3, control of the speed between the rough rolling outlet and the hot coil box inlet, is as follows:

[0024] When the strip is rolled in the last pass, under normal circumstances, the biting speed, rolling speed and throwing speed need to be set according to the position of the strip. In this scheme, on the one hand, there is no normal biting and throwing signal, so the conversion between the three speeds cannot be realized, and on the other hand, there is no direct contact between the strip and each roll gap, so it is not necessary to consider the flow of the strip and set the biting, rolling and throwing speeds. Therefore, in this technical solution, by setting a separate rolling speed, that is, the normal throwing speed, the rolling speed can meet the requirements of the rolling deceleration of the downstream hot coil box inlet process, and the rolling rhythm can be improved to realize rapid rolling.

[0025] Compared with the prior art, the present application has the following advantages: the present application is directed to a strip steel with large temperature fluctuation, and the model control of the temperature in the rough rolling area and the rolling mode. Through the implementation of the present application, the control requirement of the large temperature fluctuation of the strip steel can be realized, and on the basis of not changing the original equipment layout and process conditions of the rolling line, uninterrupted full-automatic production in a high rhythm rolling mode can be realized (see Table 1 for the production comparison). The swing design not only reduces the equipment investment cost, but also ensures the temperature control in different areas. Through the design of the 1+6 rolling mode of the rough rolling, the rolling load of the R2 rolling mill is ensured, that is, the equipment is protected, and the on-site production is also protected, which belongs to the original control mode. The swing position is placed before the R2 rolling mill, so that the production specification range of the rolling line is ensured (see Table 2), and the production limitation caused by the insufficient length of the roller is avoided.

[0026]

[0027] Table 1: Actual production situation of the strip steel with large rolling temperature fluctuation

[0028] thickness width intermediate slab thickness length max 4.3 mm 1300 mm 42 mm 4600 mm min 1.5 mm 1000 mm 35 mm 9700 mm

[0029] Table 2: Specification range of the strip steel with large rolling temperature fluctuation DETAILED DESCRIPTION

[0030] In order to deepen the understanding of the present application, the present application will be described in detail in combination with the embodiments.

[0031] Embodiment 1: A hot rolling rough rolling method of a strip steel with large temperature fluctuation, the method comprising the following steps:

[0032] S1, swing equipment and logic control during rough rolling temperature drop;

[0033] S2, realization of new product rolling strategy in the rough rolling model;

[0034] S3, control of the speed between the rough rolling outlet and the hot coil box inlet.

[0035] Step S1, swing equipment and logic control during rough rolling temperature drop, specifically as follows:

[0036] Since the temperature needs to be reduced by 210℃ in the rough rolling area, and the rolling in the rough rolling area is not affected, in order to realize this product requirement, the temperature needs to be reduced after the last rolling mill in the rough rolling is rolled, so various factors such as the strip steel specification, the on-site equipment layout, the temperature drop time, etc. need to be considered.

[0037] S11, determination of the swing position, the strip steel needs to be reduced by 210℃, and at this time the strip steel has completed the rolling of the rough rolling, so the length of the strip steel has reached the length of the hot rolling intermediate billet;

[0038] Length calculation formula: Len = (slab original length x slab thickness x slab width) / (strip intermediate slab thickness x strip roughing exit target width)

[0039] According to the product variety of Meigang hot rolling, the length of the strip after rough rolling is calculated to be up to 51 m, while the length from the rough rolling exit to the finish rolling entrance is only 60 m. When the strip swings, the strip will rush into the rack due to inertia, causing scrap steel. The length of the roller way between R1 and R2 is 100 m, which meets the swing requirement, so the swing position of the strip is placed here.

[0040] S12, swing logic implementation, after the swing position of the strip is determined, in order to realize swing cooling, the strip needs to be forced to stop and enter the swing. The swing function of Meigang hot rolling is still used for emergency treatment when production problems occur, so the swing function can be started only after the strip stops for 30 s. When new products are rolled, the R2 equipment is forced to be red-handed to prevent the strip from rolling in the last pass of R2, and the swing cooling function is automatically started after 30 s.

[0041] S13, determination of the starting point of the swing, in order to protect the on-site equipment and prevent the strip from rushing into the rack equipment due to inertia, the starting point of the swing is moved closer to the middle, and the starting point is determined as the front group of the strip distribution roller way, and the ending position is determined as the position 1 meter away from the front of R2 rolling mill.

[0042] S2, realization of new product rolling strategy in rough rolling model;

[0043] In order to make up for the defect of insufficient roller way length, the swing position is moved forward to the last pass before R2. After the swing, the temperature has been reduced to the temperature of the finish rolling entrance, which cannot meet the requirements of the last pass of R2, so the last pass needs to be skipped. In order to meet the requirements of product rolling specifications and rolling mill load, the rolling strategy of the rough rolling mill needs to be adjusted.

[0044] S21, determination of the rough rolling strategy, in order to ensure that the last pass is skipped and the load of each pass is not over limited, the original rough rolling strategy is changed from 1+5 rolling method to 1+7 rolling, and the 7 passes are skipped, which is equivalent to 1+6 rolling;

[0045] S22, realization of rolling strategy, in order to realize 1+6 rolling method, the control logic of the equipment and model needs to be completed,

[0046] First, on the equipment, because the last pass is empty, and the strip is being rolled on the reverse pass, when the temperature drops to the target temperature, the strip needs to be moved to the next process for rolling in time. In the normal mode, the strip enters the next time sequence, which requires the on-site equipment to collect signals, that is, the last pass of the R2 rolling mill is used to judge the position and move the strip by using the rolling force. In the empty mode, the equipment roll gap is raised, there is no rolling force, and a steel biting and throwing signal of the rolling mill needs to be artificially synthesized. In this technical solution, the steel biting and throwing signal of the rolling mill is simulated by judging the position information of the strip head and tail calculated according to the roll speed and time through the on-site thermal sensor signal.

[0047] Secondly, in the model setting, the 1+6 rolling mode needs to consider the redistribution of the load and the setting of the rough rolling target width and thickness. When rolling for 6 passes, the last pass of the strip is reverse rolling, and the edger roller is empty. Therefore, the width reduction control (i.e. edger rolling) is only for 5 passes of rolling, while the thickness control (i.e. horizontal roller rolling) is for 6 passes of rolling. When setting the parameters, the edger parameters need to be configured and calculated according to the 5-pass rolling mode, and the horizontal roller parameters need to be configured and calculated according to the 6-pass rolling mode. When setting the model, the rough rolling target width is reached at the fifth pass, and the rough rolling thickness target is reached at the sixth pass.

[0048] S23, the implementation of the descaling code, to rapidly cool down, the descaling water between the stands is fully opened,

[0049] S24, protection of the R2 post-process equipment, to ensure that the post-process equipment is not damaged due to errors in this process, the roll gap deviation protection is added, which generally refers to the deviation between the actual lifting of the roll gap and the model setting thickness.

[0050] Step S3, control of the speed between the rough rolling outlet and the hot coil box inlet, which is as follows:

[0051] When the strip is rolled in the last pass, under normal circumstances, the biting speed, rolling speed and throwing speed need to be set according to the position of the strip. In this scheme, on the one hand, there is no normal biting and throwing signal, so the conversion between the three speeds cannot be realized, and on the other hand, there is no direct contact between the strip and each roll gap, so it is not necessary to consider the flow of the strip and set the biting, rolling and throwing speeds. Therefore, in this technical solution, a separate rolling speed is set, which is the normal throwing speed, which not only meets the rolling deceleration requirement of the downstream hot coil box inlet process, but also improves the rolling rhythm and realizes rapid rolling. Specific embodiments:

[0053] 1422 Specifications of the rolled strip of the hot rolling line:

[0054] thickness width slab width number of blocks intermediate slab thickness 3.5 1113 1113-1133 1 40 2.75 1163 1163-1183 1 40 2.0 1095 1095-1115 4 40

[0055] Slab requirement: reduction amount ≤ 20mm, slab thickness 230mm, slab length 9.0-9.2m cold slab.

[0056] The rough rolling area control method is as follows:

[0057] Step one: swing equipment and logic control during rough rolling temperature drop

[0058] 1. After the strip is rolled for 6 passes, the site needs to force R2 to hold the red hand and not to enter the steel. The experimental strip stops swinging between R1 and R2;

[0059] 2. The throw distance needs to avoid HMD47 when rolling in reverse each time. The strip stops swinging after a certain time (30 seconds) between R1 and R2, considering the starting position of the swing 1 meter forward, so as not to hit the swing range;

[0060] Step two:

[0061] 1. Adopt 1+7 rolling mode, 6 passes to roll the slab to 40mm, 7 passes R2 roll gap swing 45mm;

[0062] 2. Ensure that the rough rolling temperature of the last pass is ≥930℃, and ensure that the RDT after swinging is 860±20℃ according to the R2 entrance pyrometer;

[0063] 3. Rough rolling descaling code "01" means "R1 entrance two groups + R1 exit two groups + R2 1st, 2nd, 3rd, 4th, 5th, 6th, 7th pass";

[0064] 4. To protect the safety of the equipment, when the 7th pass is empty, the 7th pass roll gap > 50mm, alarm, not allowed to enter the steel, the deviation between the set roll gap and the set thickness < 10mm, not allowed to enter the steel.

[0065] Step three: control of speed between rough rolling outlet and hot coil box inlet

[0066] Each pass of rough rolling is rolled at the lowest speed (1st pass 110, 2nd pass 195, 3rd pass 220, 4th pass 230, 5th pass 200, 6th pass 200, 7th pass 200).

[0067] After production, the rolling data of the rough rolling area is shown in the following table:

[0068] The target 6th pass rolled RDT is ≥930℃, and the rolled temperature after the 6th pass swinging is ≤860℃. R1 roll gap 183mm, slab thickness 230mm, reduction 47mm, R2 7 passes, 7 passes descaling fully open.

[0069]

[0070]

[0071] It should be noted that the above examples are not intended to limit the scope of the present application, and any equivalent variations or substitutions made on the basis of the above technical solutions all fall within the scope of the present application.

Claims

1. A hot-rolled roughing method for strip steel with large temperature fluctuations, characterized in that, The method includes the following steps: S1. Oscillation equipment and logic control during rough rolling temperature drop; S2, Implementation of new product rolling strategy in roughing model; S3. Speed ​​control between the roughing mill exit and the hot coil box inlet; Specifically, step S1, the oscillation device and logic control during the temperature drop of the rough rolling mill, is as follows: S11. Determining the swing position: The strip needs to be cooled by 210℃, and at this time the strip has completed the rough rolling, so the length of the strip has reached the length of the hot-rolled intermediate billet. Length calculation formula: Len = (original slab length × slab thickness × slab width) / (intermediate strip slab thickness × target width of strip roughing mill exit); S12. Swinging logic implementation: After the swaying position of the strip is determined, in order to achieve swaying cooling, the strip needs to be forced to stop and enter swaying. The swaying function can only be started 30 seconds after the strip stops. When rolling new products, the steel feed is stopped by forcing the second stand of the roughing mill R2 to prevent the strip from rolling the last pass of R2. The swaying cooling function will be automatically activated after 30 seconds. S13. Determining the starting point of the swing: In order to protect the equipment on site and prevent the strip from rushing into the frame equipment due to inertia, the starting point of the swing is moved closer to the middle. The starting position is determined to be the group in front of the strip distribution roller table, and the ending position is determined to be 1 meter away from the R2 mill. Step S2, the implementation of the new product rolling strategy in the roughing model, is as follows: S21. Determination of roughing rolling strategy The roughing rolling strategy is set to 1+7 rolling, with the 7th pass being skipped, which is equivalent to 1+6 rolling. S22. Implementation of the rolling strategy: To implement the 1+6 rolling method, the control logic for the equipment and model needs to be completed. Firstly, on the equipment, since the last pass is empty and the strip is being rolled in the reverse pass, when the temperature drops to the target temperature, the strip needs to be moved to the next process for rolling in a timely manner. In normal mode, the strip needs to collect signals on-site when entering the next sequence, that is, the position is judged and the strip moves by using the pressing force of the last pass of the R2 mill. In the empty pass mode, the roll gap of the equipment is raised and there is no pressing force, so a bite and throw signal of the mill needs to be manually synthesized. Secondly, in terms of model setting, the 1+6 rolling mode needs to consider the redistribution of load and the setting of the target width and thickness for roughing. In 6-pass rolling, the last pass of the strip is reverse rolling, during which the vertical rolls pass without load. Therefore, width control (vertical roll rolling) involves only 5 passes, while thickness control (horizontal roll rolling) involves 6 passes. When setting parameters, the vertical roll parameters need to be configured and calculated based on the 5-pass rolling method, and the horizontal roll parameters need to be configured and calculated based on the 6-pass rolling method. In the model setting, the target width for roughing is reached by the fifth pass, and the target thickness is reached by the sixth pass. S23. Implementation of the descaling code: To rapidly cool down, all descaling water in the racks is turned on. Protection for subsequent equipment S24 and R2: Since the last pass of roughing is skipped, to ensure that subsequent equipment is not damaged due to errors in this process, protection against roll gap deviation has been added. Roll gap deviation refers to the difference between the actual roll gap lift and the thickness set in the model. Step S3: Speed ​​control between the roughing mill exit and the hot coil box inlet. Under normal circumstances, when the strip passes through the last rolling pass, the bite speed, rolling speed and strip throwing speed need to be set according to the position of the strip.

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