Method for reducing weight of cut waste after roll replacement of pickling rolling mill combined unit

Abstract

The invention relates to the technical field of rolling processes, in particular to a method for reducing the weight of cut waste after roll replacement of a pickling rolling mill combined unit, which comprises the following steps: after roll replacement of a rolling mill, roll gaps of a 2 # rack, a 3 # rack and a 4 # rack are adjusted by increasing rolling forces of the 2 # rack, the 3 # rack and the 4 # rack; the inclination values of all the racks are adjusted based on the rolling force deviation recorded before roller replacement of the rolling mill; after starting, controlling the deviation value to be within a preset threshold value by observing the tension deviation and rolling force deviation change of each rack, and increasing the running speed of the rolling mill; the change condition of the strip steel thickness of the third rack is observed, when the strip steel thickness of the third rack is reduced, the forced shearing function of the rolling mill is triggered, the strip steel with the thickness out of tolerance is cut off, the strip steel thickness of an outlet of the fifth rack reaches the target thickness, and the weight of large-replacement waste of the rolling mill is reduced. The machining cost of the cold hardening procedure is reduced, the productivity utilization rate and the product thickness precision are improved, and operation is easy and convenient.

Description

Technical Field

[0001] The invention relates to the technical field of rolling technology in the steel and metallurgical industry, and in particular to a method for reducing the weight of scrap removed after roll replacement in a pickling mill combined unit. Background Art

[0002] In the production process of the pickling mill combined unit, fully continuous endless rolling of the strip is usually achieved. However, when the rolls reach the end of their service life or the product specifications need to be changed, the pickling mill combined unit must perform a roll change operation to replace the working rolls and intermediate rolls of the 1-5 stands. When the mill is started after the roll change, due to the lag of the automatic thickness control system (AGC), the starting of the rolling mill unit is prone to cause the strip thickness to exceed the tolerance. This situation will not only cause the over-thick part of the back line to deviate, but may also bring the risk of cracking to the user during the use and processing. In order to ensure product quality, the pickling mill unit must cut off the strip with excessive thickness, and the weight of the scrap removed is directly related to the yield rate and operation rate of the unit.

[0003] While several solutions exist to address the issue of out-of-tolerance strip thickness after roll changes, most methods still suffer from poor control over the weight of the scrap removed. This results in excessive scrap weight, which in turn reduces the yield and operating efficiency of the production line. Furthermore, existing technologies have not achieved ideal results in improving product thickness accuracy, making it difficult to meet increasingly stringent production requirements.

[0004] Therefore, in view of the shortcomings of the existing technology, there is an urgent need for an innovative operating method that can improve the yield rate of the pickling mill combined unit, enhance the thickness accuracy of the product, and effectively reduce the weight of the scrap removed after the roll change. The present invention proposes a method based on reducing the weight of scrap removed after the roll change of the pickling mill combined unit. After the pickling mill combined unit changes the rolls, the operating method of the present invention is adopted to reduce the fluctuation range of the strip thickness and reduce the lag of the AGC thickness adjustment. Due to the use of the existing operating method, the fluctuation range of the strip thickness after the roll change is reduced, and the weight of the scrap is reduced. Therefore, the proposed operating method can greatly reduce the weight of scrap and improve the unit's production capacity and yield rate. Summary of the Invention

[0005] The present application aims at the technical problem of excessive cutting of waste product weight, low material yield and operation rate after roll replacement of the existing pickling and rolling mill combined unit, and provides a method for reducing the waste product weight after roll replacement of the pickling and rolling mill combined unit. The present application mainly uses technical solutions such as optimization of rolling mill working mode switching, system information synchronization, rolling force and roll gap adjustment, rack inclination value setting and precise control of forced shearing opportunity, which is different from the rough regulation and control of the rolling process after roll replacement in the prior art. Through fine operation steps, the hysteresis of the automatic thickness control system (AGC) is effectively compensated, and the thickness deviation is reduced. Thus, the effect of significantly reducing the waste product weight, improving the material yield and operation rate of the unit, improving the product thickness precision, and ensuring the quality and efficiency of subsequent processing is achieved.

[0006] The technical means adopted by the present application are as follows:

[0007] The method for reducing the waste product weight after roll replacement of the pickling and rolling mill combined unit comprises the following steps:

[0008] After roll replacement of the rolling mill, the rolling mill operating mode is switched from roll replacement preparation mode to rolling mode;

[0009] The rolling force of the 2nd rack, the 3rd rack and the 4th rack is increased, and the roll gap of the 2nd rack, the 3rd rack and the 4th rack is adjusted to compensate for the roll gap control amount of the automatic thickness control system and reduce the roll gap control hysteresis time;

[0010] Based on the rolling force deviation recorded before roll replacement of the rolling mill, the inclination values of all racks are adjusted;

[0011] After starting the car, the tension deviation and the rolling force deviation of each rack are observed, and when the deviation value is within the preset threshold, it is ensured that the parameters of each rack of the rolling mill are normal, the strip shape is flat, and the shearing speed of the rolling mill is improved;

[0012] The change of the strip thickness of the 3rd rack is observed, and when the strip thickness of the 3rd rack decreases, the forced shearing function of the rolling mill is triggered to cut off the part of the strip with thickness deviation, so that the strip thickness at the outlet of the 5th rack reaches the target thickness, and the waste product weight of the rolling mill is reduced.

[0013] Further, the adjustment of the rolling mill roll gap by increasing the rolling force of the 2nd rack, the 3rd rack and the 4th rack comprises:

[0014] The rolling force of the 2nd rack, the 3rd rack and the 4th rack is increased by 100-500 tons, and the roll gap of the 2nd rack, the 3rd rack and the 4th rack is reduced by 0.1-0.4 mm.

[0015] Further, the amount of rolling force increase is adjusted according to the material and thickness of the strip, specifically:

[0016] When the strip is mild steel and its thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 100-200 tons;

[0017] When the strip is mild steel and its thickness is greater than 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 200-300 tons;

[0018] When the strip is high-strength steel and its thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 200-300 tons;

[0019] When the strip steel is high-strength steel and its thickness is greater than 1.0 mm, the rolling force of the 2# stand, 3# stand and 4# stand increases by 300-500 tons.

[0020] Furthermore, the step of increasing the shearing speed of the rolling mill comprises:

[0021] When the strip thickness is less than or equal to 1.0 mm, the shearing speed of the rolling mill is increased to 120-150 m / min;

[0022] When the strip thickness is greater than 1.0 mm, the shearing speed of the rolling mill is increased to 100-120 m / min.

[0023] Furthermore, the method further comprises:

[0024] When the rolling mill is working, reduce the roll speed of the 2# and 3# stands to accelerate the strip thickness at the 5# stand outlet to reach the target set value.

[0025] Furthermore, based on the rolling force deviation recorded before the roll change, all stand tilt values ​​are adjusted, specifically:

[0026] Record the rolling force deviation of all stands before roll change;

[0027] After the new roll is installed and calibrated, the rolling force is applied to the set value;

[0028] Adjust the inclination of all stands so that the rolling force deviation of each stand is the same as the rolling force deviation when the old roll is stopped to ensure the stability of the rolling force.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] This invention optimizes post-roller-changing operations, reduces scrap removal, improves yield and operating rates, increases the output of qualified products, and enhances capacity utilization. Furthermore, by rationally adjusting roll speed and rolling force compensation and precisely controlling the speed and timing of forced shearing, it effectively reduces thickness deviations and improves product thickness accuracy. Furthermore, it reduces scrap weight, raw material waste, scrap disposal costs, subsequent processing issues, and chilling process costs.

[0031] Based on the above reasons, the present invention can be widely promoted in fields such as rolling technology in the steel and metallurgical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 The present invention is a flow chart of a method for reducing the weight of scrap removed after roll replacement in a pickling mill combination unit. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0035] like Figure 1 As shown, the present invention provides a method for reducing the weight of scrap removed after roll change in a pickling mill combination unit, the steps of which are as follows:

[0036] S1. After the rolling mill rolls are changed, the rolling mill operation mode is switched from the roll change preparation mode to the rolling mode.

[0037] S2. By increasing the rolling force of the 2#, 3# and 4# stands, adjust the roll gap of the 2#, 3# and 4# stands to compensate for the roll gap control amount of the automatic thickness control system and reduce the roll gap control lag time.

[0038] Specifically, the rolling force of the 2nd, 3rd and 4th stands is increased by 100-500 tons, and the roll gap of the 2nd, 3rd and 4th stands is reduced by 0.1-0.4 mm. When the strip steel is soft steel and the thickness is less than or equal to 1.0 mm, the rolling force of the 2nd, 3rd and 4th stands is increased by 100-200 tons; when the strip steel is soft steel and the thickness is greater than 1.0 mm, the rolling force of the 2nd, 3rd and 4th stands is increased by 200-300 tons; when the strip steel is high-strength steel and the thickness is less than or equal to 1.0 mm, the rolling force of the 2nd, 3rd and 4th stands is increased by 200-300 tons; when the strip steel is high-strength steel and the thickness is greater than 1.0 mm, the rolling force of the 2nd, 3rd and 4th stands is increased by 300-500 tons.

[0039] S3. Based on the recorded rolling force deviation before the roll change of the rolling mill, adjust the inclination values of all stands.

[0040] Specifically, the rolling force deviation of each stand of the 1st to 5th stands under the old roll state is recorded when the rolling mill is stopped, and after the new roll is loaded and calibrated, the rolling force is loaded to the set value, and the inclination of the 1st to 5th stands is adjusted so that the rolling force deviation of each stand is the same as the rolling force deviation when the old roll is stopped.

[0041] S4. After starting, the tension deviation and rolling force deviation of each stand are observed to control the deviation value within the preset threshold to ensure that the parameters of each stand of the rolling mill are normal, the strip shape is flat, and the shearing speed of the rolling mill is improved.

[0042] Specifically, when the thickness of the strip steel is less than or equal to 1.0 mm, the shearing speed of the rolling mill is increased to 120-150 m / min; when the thickness of the strip steel is greater than 1.0 mm, the shearing speed of the rolling mill is increased to 100-120 m / min. When the rolling mill is working, the rolling speed of the 2nd and 3rd stands is reduced to accelerate the thickness of the strip steel at the outlet of the 5th stand to reach the target set value.

[0043] S5. The thickness change of the strip steel at the 3rd stand is observed, and when the thickness of the strip steel at the 3rd stand decreases, the forced shearing function of the rolling mill is triggered to cut off the part of the strip steel with thickness out of tolerance, so that the thickness of the strip steel at the outlet of the 5th stand reaches the target thickness, and the weight of the waste product of the rolling mill is reduced.

[0044] Specifically, the actual thickness change trend of the 3rd stand is continuously checked. When the thickness of the 3rd stand decreases, a forced shearing instruction is sent through the main control screen to cut off the part of the strip steel at the 5th stand in advance. The shearing signal is triggered, and because the shearing process needs 15 seconds of time, it is equivalent to triggering the shearing in advance, and when the shearing is completed, the thickness at the outlet of the 5th stand also reaches the target thickness.

[0045] The above S1-S5 are sequentially executed.

[0046] Embodiment

[0047] In order to reduce the weight of the cut-off waste after the roll change of the pickling and rolling mill combination, the following operations are performed:

[0048] First, the mode is switched from ROLLCHARGE to ROLLING on the rolling mill control interface. Then, the CURRENT / NEXTRESEND button is clicked multiple times to match the secondary system information with the primary rolling mill master MASTER. The friction coefficient compensation, roll wear compensation, roll gap compensation, and rolling force compensation of the upper set of rolls are cleared in the secondary model of the rolling mill. The new roll information is used in the secondary model to clear and recalculate the friction coefficient compensation, roll wear compensation, roll gap compensation, and rolling force compensation, thereby reducing the impact of the non-cleared compensation coefficients on the rolling mill gap setting and the thickness adjustment time.

[0049] Then, the RESSET button is clicked on the ROLLFORCEOPE interface of the primary screen 601 to restore the actual rolling force to the set value.

[0050] In the #3GAP and #4GAP interfaces of the primary screen 601, the CLOSE button is clicked to reduce the roll gap of the 3# and 4# stands by 0.1-0.4 mm, which corresponds to an increase of 100-500 tons in rolling force. When the strip is soft steel and the thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3#, and 4# stands is manually increased by 100-200 tons. When the strip is soft steel and the thickness is greater than 1.0 mm, the rolling force of the 2#, 3#, and 4# stands is manually increased by 200-300 tons. When the strip is high-strength steel and the thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3#, and 4# stands is manually increased by 200-300 tons. When the strip is high-strength steel and the thickness is greater than 1.0 mm, the rolling force of the 2#, 3#, and 4# stands is manually increased by 300-500 tons.

[0051] At the same time, according to the rolling force deviation before the roll change, the inclination values of the 1-5# stands are set in the screen to make the rolling force deviation of each stand the same as that when the old roll is stopped. Then, the THREAD button is pressed on the main control console to execute the point motion start-up, and the tension deviation of each stand is observed in real time. If the deviation exceeds the preset range, it is immediately manually adjusted to be stable. Then, the shearing speed of the rolling mill is increased. When the strip thickness is less than or equal to 1.0 mm, the shearing speed of the rolling mill is increased to 120-150 m / min. When the strip thickness is greater than 1.0 mm, the shearing speed of the rolling mill is increased to 100-120 m / min.

[0052] During the operation of the rolling mill, the roll speed of the 2# and 3# stands can be appropriately reduced to accelerate the strip thickness at the outlet of the 5# stand to reach the target set value.

[0053] Next, click the ON button in the COOLANT & AIR interface of the first-level screen 601 to activate the cooling and pneumatic system. Monitor the tension deviation and rolling force deviation of each stand to ensure that they are stable within the preset range, and adjust the parameters of each stand to ensure that the strip shape is flat.

[0054] Continuously check the actual thickness trend of the 3# stand. When the actual thickness of the 3# stand starts to decrease from the out-of-tolerance state and approaches the set value, the main control immediately sends a COMPULSION CUT command in the first-level screen 620. After the cutting is completed, confirm that the 5# stand outlet thickness meets the target value, and end the post-rolling adjustment process. The trigger cutting opportunity is when the 3# stand thickness converges from out-of-tolerance to the set value, avoiding excessive cutting.

[0055] Through the above operations, the weight of the cutting waste after the pickling and rolling mill combined unit changes the roll can be effectively reduced, the unit yield and operation rate can be improved, the strip thickness accuracy can be ensured, and the subsequent processing risk can be reduced.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for reducing the weight of scrap removed after roll change in a pickling mill combination unit, characterized in that: The following steps are involved: After the rolling mill rolls are changed, the rolling mill operation mode is switched from the roll change preparation mode to the rolling mode; By increasing the rolling force of the 2#, 3# and 4# stands, the roll gaps of the 2#, 3# and 4# stands are adjusted to compensate for the roll gap control amount of the automatic thickness control system and reduce the roll gap control lag time; Adjust the tilt values ​​of all stands based on the rolling force deviation recorded before the roll change; After starting the mill, the tension deviation and rolling force deviation of each stand are observed and the deviation value is controlled to be within the preset threshold to ensure that the parameters of each stand of the mill are normal, the strip shape is straight, and the shearing speed of the mill is increased; Observe the changes in the strip thickness of the 3# stand. When the strip thickness of the 3# stand decreases, trigger the forced shearing function of the rolling mill to cut off the strip with excessive thickness, so that the strip thickness at the outlet of the 5# stand reaches the target thickness, reducing the weight of scrap during large-scale replacement of the rolling mill.

2. The method for reducing the weight of scrap removed after roll change in a pickling mill combination unit according to claim 1, characterized in that: The method of adjusting the roll gap of the rolling mill by increasing the rolling forces of the 2# stand, the 3# stand and the 4# stand comprises: The rolling force of the 2#, 3# and 4# stands is increased by 100-500 tons, and the roll gap of the 2#, 3# and 4# stands is reduced by 0.1-0.4 mm.

3. The method for reducing the weight of scrap removed after roll change in a pickling mill combination unit according to claim 2, characterized in that: The amount of rolling force increase is adjusted according to the material and thickness of the strip, specifically: When the strip is mild steel and its thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 100-200 tons; When the strip is mild steel and its thickness is greater than 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 200-300 tons; When the strip is high-strength steel and its thickness is less than or equal to 1.0 mm, the rolling force of the 2#, 3# and 4# stands is increased by 200-300 tons; When the strip steel is high-strength steel and its thickness is greater than 1.0 mm, the rolling force of the 2# stand, 3# stand and 4# stand increases by 300-500 tons.

4. The method for reducing the weight of scrap removed after roll change in a pickling mill combination unit according to claim 1, characterized in that: The method of increasing the shearing speed of the rolling mill comprises: When the strip thickness is less than or equal to 1.0 mm, the shearing speed of the rolling mill is increased to 120-150 m / min; When the strip thickness is greater than 1.0 mm, the shearing speed of the rolling mill is increased to 100-120 m / min.

5. The method for reducing the weight of scrap removed after roll change in a pickling mill combination unit according to claim 1, characterized in that: The method further comprises: When the rolling mill is working, reduce the roll speed of the 2# and 3# stands to accelerate the strip thickness at the 5# stand outlet to reach the target set value.

6. The method for reducing the weight of scrap removed after roll change in a pickling mill combination unit according to claim 1, characterized in that: Based on the rolling force deviation recorded before the roll change, adjust the tilt values ​​of all stands, specifically: Record the rolling force deviation of all stands before roll change; After the new roll is installed and calibrated, the rolling force is applied to the set value; Adjust the inclination of all stands so that the rolling force deviation of each stand is the same as the rolling force deviation when the old roll is stopped to ensure the stability of the rolling force.

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