A process online adjustment method based on hot rolling roll iron sheet classification

Abstract

A process online adjustment method based on hot rolling roll iron scale classification includes the following steps: S1: L2 determines the category of roll iron scale defects and the corresponding number of defects according to the real-time strip surface map; S2: determines the roll iron scale defect level according to the determination of the roll iron scale defect category and the corresponding number of defects; S3: establishes process adjustment for the current strip according to the determination of the roll iron scale defect level of the previous strip; the process online adjustment method establishes adaptive dynamic adjustment of the process through the above steps. The process online adjustment method based on hot rolling roll iron scale classification of the present invention realizes the online adjustment of the process through the established adaptive method, without stopping the machine, thereby improving production efficiency.

Description

Technical Field

[0001] The invention belongs to the field of hot rolling of steel, and in particular relates to an online process adjustment method based on hot rolling roll sheet classification. Background Art

[0002] Roller scale is one of the most common defects in hot rolling, and it is also the focus and difficulty of quality control for hot rolling production enterprises. The flow of hot-rolled strip is generally divided into pickling, cold rolling feeding and high-strength series products. Among them, the high-strength series products are generally thicker, less likely to produce roll scale and have lower surface requirements; while other products are basically used in the fields of automobiles, home appliances, etc., with higher requirements for the surface quality of strip steel, and obvious roll scale indentation defects are not allowed on the surface, otherwise it will seriously affect the use of users.

[0003] Roller iron sheet, as the name implies, is a defect caused by the damage to the roll surface. This defect is closely related to the surface quality of the finishing roll. This defect generally does not occur when the roll surface is good, but gradually appears as the roll surface deteriorates. In order to control this defect, it is necessary to refine the process starting from the heating process. For specific surface quality control processes and procedures, please refer to Figure 1 .

[0004] The strip steel 1 is in the heating furnace (11), and the furnace discharge temperature and each heating time must meet the process requirements. After the steel is drawn, it needs to pass through the 1# descaling box (14) to remove the furnace-generated oxidized iron scale, and then it is rolled through the roughing mill (3, 5, 7, 9, the same below) and the vertical rollers (2, 4, 6, 8). Among them, in order to control the iron scale of the rolling rolls, the R2 rolling mill (5) preferably adopts 3-pass rolling, and the roughing mill descaling (15, 16, 17, 18, 19) is controlled according to the requirements of the intermediate billet temperature (10). After leaving the roughing area, it enters the finishing area for rolling, and the finishing rolling is 7 stands (12 is F1, 13 is F7), and 20 is the 2# descaling box.

[0005] Although the roll scale is produced in the finishing rolling area, the main hot rolling processes such as heating temperature control, rolling passes, descaling and finishing rolling load distribution have a direct impact on the production of roll scale. As a large-scale production line, the machine output of the hot rolling production line is generally above 500t / h. Stable batch production is the premise for the utilization of production capacity and the need for low-cost operation of the enterprise. Therefore, the design principle of the hot rolling process is to take into account the surface quality control as much as possible under the premise of ensuring rolling stability, and to implement the response measures when quality problems occur as a reaction plan.

[0006] The actual hot rolling process, functional accuracy, and process design that focuses on ensuring stability will inevitably lead to quality fluctuations. Taking Baosteel's 2050 hot rolling production line as an example, defects in the roll iron sheet occurred many times during normal production: on the one hand, it was difficult for quality inspectors to accurately judge the trend, and they only issued warnings after defects occurred; on the other hand, after receiving quality warnings, operators only temporarily adjusted some processes based on their own experience, which often led to multiple quality defects and even shutdowns for roll replacement, which had a great impact on normal production and quality control. To this end, it is necessary to comprehensively consider the online adjustment functions and strategies of the roll iron sheet to reduce the resulting shutdowns and quality fluctuations.

[0007] The utility model application with application number: 201720622680.X discloses a "hot-rolled plate high-pressure water descaling iron oxide collection device". It includes an upper box body, a lower box body, an upper spray pipe, a lower spray pipe and rollers for transporting slabs, which are fixed on a roller frame. The characteristics are that at least two groups of upper spray pipes are arranged in the lower box body, and two groups of collectors with a biased structure are arranged correspondingly thereto. The collectors and upper spray pipes are on the same horizontal plane and are all above the transport roller. The upper spray pipe and the collector are respectively installed at the upper part of the side wall of the lower box body; at least two groups of lower spray pipes are arranged in the lower box body, which are placed below the transport roller, and the two ends are respectively installed at the lower part of the roller frame.

[0008] The invention application with application number: 201910456692.3 discloses "an online adjustment method for rolling oil based on hot rolling roll iron scale classification", which involves the field of online detection technology of hot rolling surface, including the setting of the initial value of rolling oil opening, the collection of strip roll iron scale defects, the calculation logic of rolling oil opening, and the formulation of rolling oil use strategy according to the surface grade measured by the surface meter. The present invention combines the use of rolling oil with the roll iron scale defects detected by the surface meter, and puts it into use only when roll iron scale appears and meets certain conditions, which can greatly reduce the number of rolling oil coils put into use and reduce the consumption of rolling oil; the defect level is confirmed according to the roll iron scale grade and the number of defects on the strip surface, realizing the online dynamic adjustment of rolling oil concentration, and further exerting the role of rolling oil in improving the surface quality of strip. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a process online adjustment method based on hot rolling roll iron sheet classification, and its technical solution is as follows:

[0010] A process online adjustment method based on hot rolling roll iron sheet classification, characterized by comprising the following steps:

[0011] S1: L2 determines the degree of defects of the roll iron scale and counts the corresponding number of defects based on the real-time strip surface map;

[0012] S2: Determine the level of roll sheet defects according to the determination of the roll sheet defect category and the corresponding number of defects counted;

[0013] S3: Establishing process adjustment for the current strip according to the determination of the level of the iron scale defect of the roll system of the previous strip;

[0014] The process online adjustment method establishes adaptive dynamic adjustment of the process through the above steps.

[0015] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0016] The process adjustment described in step S3 is completed by adjusting the process factors corresponding to the main influencing factors of the roll iron sheet;

[0017] in,

[0018] The process factors are arranged in descending order according to their relevance to the roll iron sheet.

[0019] The corresponding adjustment is formed by establishing a corresponding relationship between a process factor sequence with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale;

[0020] The main influencing factors of the roll iron sheet are the finishing load and the intermediate billet temperature.

[0021] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0022] The process factors corresponding to the factors affecting the finishing rolling load are: the load distribution of finishing rolling itself, the thickness of the intermediate billet and the cooling of the rolls;

[0023] The process factors corresponding to the influencing factors of the intermediate billet temperature are: the number of rough rolling dephosphorization passes;

[0024] The formation of the descending order of relevance is specifically as follows:

[0025] First relevance: load distribution of the finishing mill F2 and F3 stands;

[0026] Second relevance: intermediate billet thickness;

[0027] The third relevance: roll cooling and rough rolling dephosphorization pass.

[0028] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0029] The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically:

[0030] The regulation is established in a one-to-one correspondence with the order of the iron sheet defect levels of the rolling mill system from low to high in a manner of successively accumulating and increasing regulation of the process factor sequence with decreasing relevance to the rolling mill system.

[0031] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0032] The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically:

[0033] The levels of defects of the roll iron sheets are from low to high: level 1 defect, level 2 defect, level 3 defect, and level 4 defect;

[0034] When it is a level 1 defect, no adjustment is made to the process factors;

[0035] When it is a level 2 defect, the adaptation is established by adjusting the load distribution of the finishing mill F2 and F3 stands of the first relevance;

[0036] When it is a level 3 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance and adjusting the thickness of the intermediate billet of the second relevance;

[0037] When it is level 4 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance, the intermediate billet thickness of the second relevance, and the roll cooling and rough rolling dephosphorization passes of the third relevance.

[0038] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0039] The degree of defects in the roll iron sheet is classified into Class 1, Class 2 and Class 3 from light to heavy according to the uniformity and peeling degree of the oxide film on the roll surface.

[0040] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0041] The level of roll sheet defects is determined based on the determination of the roll sheet defect category and the corresponding number of defects counted, specifically:

[0042] If the defect level is Class 1 and no defect points are detected, or if the defect level is Class 2 and the number of defect points counted ∈ [0,20], the defect level is set to Class 1;

[0043] If the defect level is 2 and the number of defect points counted is ∈[21,50], or if the defect level is 3 and the number of defect points counted is ∈[0,10], the defect level is set to 2;

[0044] If the defect level is 2 and the number of defect points counted is ∈[51, 200], or if the defect level is 3 and the number of defect points counted is ∈[11, 30], the defect level is set to level 3;

[0045] If the defect level is Class 2 and the number of defect points counted exceeds 201, or if the defect level is Class 3 and the number of defect points counted ∈ [31, 100], the defect level is set to Class 4;

[0046] When the defect level is Category 3 and the number of defect points counted exceeds 101, the defect level is set to Level 5, which corresponds to stopping the machine for roller replacement.

[0047] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0048] The real-time strip surface map is acquired by a CCD camera arranged on a detection bridge (located between laminar cooling and a coiler, about 2m away from laminar cooling) in conjunction with lighting or measured by a surface meter.

[0049] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0050] The load adjustment for the finishing rolling F2 and F3 stands is as follows: when it is a second-level defect, the load is reduced by 2.8% to 3.2%; when it is a third-level defect or a fourth-level defect, the load is reduced by 4.8% to 5.2%;

[0051] The specific adjustment of the intermediate billet thickness is: minus 2.8mm to 3.2mm;

[0052] The specific adjustment of the rough rolling dephosphorization passes is: reduce one set of passes;

[0053] According to the present invention, a process online adjustment method based on hot rolling roll iron scale classification is characterized by:

[0054] The roller cooling is achieved by adding a regulating valve to the original cooling water supply pipeline. When the defect is level 4, the water flow rate is increased by 9.8% to 10.2%.

[0055] The present invention is an online process adjustment method based on the classification of hot rolling roll iron scale. The online adjustment of the process is realized by establishing an adaptive method. The method does not need to stop the machine, thereby improving the production efficiency. The online adjustment of the present invention takes into account the stability of the rolling process and effectively suppresses and improves the generation of strip steel roll iron scale defects without destroying the rolling stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the rolling process of the prior art;

[0057] Figure 2 It is a schematic diagram of the adjustment steps of the present invention;

[0058] Figure 3 The table is a table of the degree of defects of the iron sheet of the rolling mill in the present invention;

[0059] Figure 4 The table is a table of iron sheet defects of the roll system in the present invention;

[0060] Figure 5 Adjusting the reference table for the process factors in the present invention;

[0061] Figure 6 This is a schematic diagram of the regulating valve added to the roller cooling in the present invention. DETAILED DESCRIPTION

[0062] Next, a process online adjustment method based on hot rolling roll iron scale classification of the present invention will be further specifically described according to the accompanying drawings and specific implementation methods of the specification.

[0063] A process online adjustment method based on hot rolling roll iron sheet classification, such as Figure 2 As shown, the following steps are included:

[0064] S1: L2 determines the degree of defects of the roll iron scale and counts the corresponding number of defects based on the real-time strip surface map;

[0065] S2: Determine the level of roll sheet defects according to the determination of the roll sheet defect category and the corresponding number of defects counted;

[0066] S3: Establishing process adjustment for the current strip according to the determination of the level of the iron scale defect of the roll system of the previous strip;

[0067] The process online adjustment method establishes adaptive dynamic adjustment of the process through the above steps.

[0068] in,

[0069] The process adjustment described in step S3 is completed by adjusting the process factors corresponding to the main influencing factors of the roll iron sheet;

[0070] in,

[0071] The process factors are arranged in descending order according to their relevance to the roll iron sheet.

[0072] The corresponding adjustment is formed by establishing a corresponding relationship between a process factor sequence with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale;

[0073] The main influencing factors of the roll iron sheet are the finishing load and the intermediate billet temperature.

[0074] in,

[0075] The process factors corresponding to the factors affecting the finishing rolling load are: the load distribution of finishing rolling itself, the thickness of the intermediate billet and the cooling of the rolls;

[0076] The process factors corresponding to the influencing factors of the intermediate billet temperature are: the number of rough rolling dephosphorization passes;

[0077] The formation of the descending order of relevance is specifically as follows:

[0078] First relevance: load distribution of the finishing mill F2 and F3 stands;

[0079] Second relevance: intermediate billet thickness;

[0080] The third relevance: roll cooling and rough rolling dephosphorization pass.

[0081] in,

[0082] The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically:

[0083] The regulation is established in a one-to-one correspondence with the order of the iron sheet defect levels of the rolling mill system from low to high in a manner of successively accumulating and increasing regulation of the process factor sequence with decreasing relevance to the rolling mill system.

[0084] in,

[0085] The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically:

[0086] The levels of defects of the roll iron sheets are from low to high: level 1 defect, level 2 defect, level 3 defect, and level 4 defect;

[0087] When it is a level 1 defect, no adjustment is made to the process factors;

[0088] When it is a level 2 defect, the adaptation is established by adjusting the load distribution of the finishing mill F2 and F3 stands of the first relevance;

[0089] When it is a level 3 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance and adjusting the thickness of the intermediate billet of the second relevance;

[0090] When it is level 4 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance, the intermediate billet thickness of the second relevance, and the roll cooling and rough rolling dephosphorization passes of the third relevance.

[0091] in,

[0092] The degree of defects in the roll iron sheet is classified into Class 1, Class 2 and Class 3 from light to heavy according to the uniformity and peeling degree of the oxide film on the roll surface.

[0093] in,

[0094] The level of roll sheet defects is determined based on the determination of the roll sheet defect category and the corresponding number of defects counted, specifically:

[0095] If the defect level is Class 1 and no defect points are detected, or if the defect level is Class 2 and the number of defect points counted ∈ [0,20], the defect level is set to Class 1;

[0096] If the defect level is 2 and the number of defect points counted is ∈[21,50], or if the defect level is 3 and the number of defect points counted is ∈[0,10], the defect level is set to 2;

[0097] If the defect level is 2 and the number of defect points counted is ∈[51,200], or if the defect level is 3 and the number of defect points counted is ∈[11,30], the defect level is set to level 3;

[0098] If the defect level is Class 2 and the number of defect points counted exceeds 201, or if the defect level is Class 3 and the number of defect points counted ∈ [31, 100], the defect level is set to Class 4;

[0099] When the defect level is Category 3 and the number of defect points counted exceeds 101, the defect level is set to Level 5, which corresponds to stopping the machine for roller replacement.

[0100] in,

[0101] The real-time strip surface map is acquired by a CCD camera arranged on a detection bridge (located between laminar cooling and a coiler, about 2m away from laminar cooling) in conjunction with lighting or measured by a surface meter.

[0102] in,

[0103] The load adjustment for the finishing rolling F2 and F3 stands is as follows: when it is a second-level defect, the load is reduced by 2.8% to 3.2%; when it is a third-level defect or a fourth-level defect, the load is reduced by 4.8% to 5.2%;

[0104] The specific adjustment of the intermediate billet thickness is: minus 2.8mm to 3.2mm;

[0105] The specific adjustment of the rough rolling dephosphorization passes is: reduce one set of passes;

[0106] in,

[0107] The roller cooling is achieved by adding a regulating valve to the original cooling water supply pipeline. When the defect is level 4, the water flow rate is increased by 9.8% to 10.2%.

[0108] Working process, principle and implementation example

[0109] Mechanism of Roller Sheet Defects

[0110] The rolling process is a thermodynamic process in which the strip is deformed by force between the rolls. Due to the direct contact between the rolls and the strip, the strip transfers its own heat and rolling force to the rolls while its thickness becomes thinner. The rolls are placed in a harsh working environment of high temperature, high speed, large rolling force, and sudden cooling and heating. The oxide film on the roll surface is continuously subjected to huge alternating stress. When a certain fatigue limit is reached, microcracks begin to appear and expand in the oxide film on the roll surface. Under the action of the strong shear stress between the roll and the strip, the oxide film on the roll surface peels off.

[0111] Once the oxide film on the working roll surface peels off, on the one hand, the peeled roll surface oxide film adheres to the surface of the hot-rolled strip, and is rolled into the strip surface in the subsequent stands to form a tertiary scale defect; on the other hand, after the oxide film on the working roll surface peels off, the roll surface becomes quite rough, and the unevenness of the roll surface can easily break through the rheological stress limit of the strip surface, producing a plowing effect on the strip surface, and the exposed matrix re-oxidized iron scale and the plowed iron scale are pressed into the strip together, and finally the matrix and oxide intertwined scale defects are formed on the strip surface. In the actual rolling process, it was found that the rolls that are prone to peeling are concentrated in the first four stands of finishing rolling, mainly because the strip temperature is high when the front stand is rolling, and the rolling reduction rate is large. Therefore, the rolls of these four stands are set as adjustment objects.

[0112] Established control mechanism

[0113] Strip steel roll iron scale defect classification:

[0114] 1. The degree of iron sheet of the roll and its corresponding relationship with the roll surface

[0115] The peeling of the iron scale of the roll system on the surface of the strip is directly related to the peeling of the roll surface. Based on years of experience, the iron scale of the roll system has become a consensus among peers. In this method, the iron scale defects of the roll system are divided into three categories from light to heavy, such as Figure 3 As shown, according to Figure 3 The table can determine the degree of iron scale of the roll series.

[0116] Among them, defect degree 1 represents an ideal state with the best surface quality of the strip; Category 2 is the initial stage of peeling of the roller surface, and the degree is relatively light. Generally, when the number of defect points is small, it can meet user requirements, and when the number of points is large, it needs to be blocked and re-judged; Category 3 is relatively serious, which will affect user use and has strict requirements on the number of defect points.

[0117] 2) Classification of strip surface roll iron scale defects

[0118] The hot rolling surface inspection system consists of a set of digital cameras and lighting units integrated on the inspection bridge (located between the laminar cooling and the coiler, about 2m away from the laminar cooling) to obtain the surface image of the strip. The image is preliminarily evaluated by the camera computer and the result is sent to the server computer system. (Note: This is a mature and known technology. The surface instrument can obtain various defined defects. Taking the roll iron scale as an example, by defining the surface defect spectrum, the surface instrument will automatically detect the defect and count the number of corresponding spectra;) The classification of the roll iron scale defects according to the degree of strip roll iron scale and the corresponding number of defects is introduced, see Figure 4 The table shown.

[0119] in:

[0120] Roller iron scale grade 1: Indicates that the roller iron scale is grade 1 or grade 2 but the number of points is not more than 20. In this case, the roller iron scale will not affect the user's use, and the roller surface degree is also relatively controlled;

[0121] Roller scale grade 2: indicates that the roll scale is grade 2 and the number of points is in the range of 21-50 or grade 3 but the number of points is not more than 10. At this time, the oxide film on the roll surface has begun to peel off slightly, and the rolling process needs to be fine-tuned;

[0122] Roller iron scale grade 3: Indicates that the roller iron scale is grade 2 and the number of points is between 51-200 or grade 3 and the number of points is between 11-30, indicating that the oxide film on the roller surface has peeled off and timely process adjustment is required to improve the roller surface quality.

[0123] Roller scale grade (grade) 4: It means that the roller scale level is 2 and the number of points is greater than 201, or the level is 3 and the number of points is greater than 31, indicating that the oxide film on the roller surface has obviously peeled off and is deteriorating. It is necessary to increase process adjustments to improve the roller surface quality as soon as possible.

[0124] Roller iron grade 5: If it exceeds the process adjustment range, the machine must be stopped and the rolls must be replaced in time to avoid batch quality accidents.

[0125] Setting logic of rolling process

[0126] According to the generation principle of roll scale and the development of a large number of tests, roll scale is mainly related to the intermediate billet temperature, intermediate billet thickness, finishing load and roll temperature. Among them, the main factors affecting the temperature of the intermediate billet are the heating process and rough rolling descaling. The adjustment lag of the heating process is large, and the performance involved in rough rolling descaling cannot be adjusted significantly. Therefore, the rough rolling descaling process can be fine-tuned from the perspective of rapid improvement. The finishing load is related to the thickness of the intermediate billet, the load distribution of the finishing rolling itself and the cooling of the rolls. Among them, the finishing load is the most direct influencing factor of the roll scale, but the impact on rolling stability must be considered, and the adjustment range cannot exceed 5%; the thickness of the intermediate billet is related to the hourly output and rolling stability, and a proper reduction is conducive to reducing the rolling force; the cooling state of the roll is closely related to the formation and peeling characteristics of the oxide film on the roll surface. Increasing the cooling of the roll is conducive to improving the state of the oxide film on the roll surface, but it is not conducive to energy saving. To this end, combined with the experience of controlling the defect of oxide scale, the rolling process parameters and adjustment logic for the roll scale were formulated. The details are as follows:

[0127] 1) Set the hot rolling process flag field in L2

[0128] The hot rolling process flag field tech_flag is set in the L2 process machine, and different values ​​are assigned to it to distinguish the production process difference control of each process of hot rolling. The explanation is as follows: starting from a roll change cycle (F1-4 work roll change), the tech_flag of the first roll is set to 0. The subsequent production rolls are executed according to the following logic: that is, according to the surface defect classification of the previous strip steel, the process machine reads the surface defect classification and sets the rolling process of the next strip steel according to the following logic.

[0129] (1) If the surface defect grade=1, then tech_flag=0, and the process remains unchanged;

[0130] (2) If the surface defect grade is 2, then tech_flag is 1, that is, only the load distribution of the F2 and F3 stands, which are most related to the roll iron scale, is adjusted to achieve the purpose of quickly improving the strip surface, and tech_flag is kept unchanged when the F1-4 working rolls are not replaced;

[0131] (3) If the surface defect grade is 3, then tech_flag is 2. On the basis of reducing the load of the F2 and F3 frames, the thickness of the intermediate billet is further thinned, and the tech_flag setting remains unchanged when the F1-4 working rolls are not replaced.

[0132] (4) If the surface defect grade is 4, then tech_flag is 3. On the basis of reducing the load of the F2 and F3 stands and thinning the thickness of the intermediate billet, the roller surface deterioration is curbed as soon as possible by increasing the roller cooling water pressure and reducing the number of descaling groups. When the F1-4 working rolls are not replaced, the tech_flag setting remains unchanged.

[0133] 2) The hot rolling process strategies corresponding to different tech_flags are shown in Figure 5 The table shown in the figure shows the set value as the optimal adjustment. Except for the optimal value, the allowable value ranges are as follows: load adjustment for the finishing rolling F2 and F3 stands: when it is a secondary defect, reduce the load by 2.8% to 3.2%; when it is a tertiary defect or a quaternary defect, reduce the load by 4.8% to 5.2%; the adjustment of the intermediate billet thickness is specifically to reduce 2.8mm to 3.2mm; the adjustment of the rough rolling dephosphorization passes is specifically to reduce one group of passes; the adjustment of the water flow is to increase it by 9.8% to 10.2%.

[0134] Increase the opening (flow) regulating valve of the roller cooling water

[0135] Add roller cooling water (flow) regulating valves to the four stands of F1-4 (such as Figure 6 The opening degree control is set by L2. The electrical control system and the host computer operating system together constitute the automatic control and regulation system of the entire roll cooling system.

[0136] Embodiment 1:

[0137] (1) For a certain electrogalvanizing plan (the surface requirements of the strip steel are high, and the rolling oil is usually fully used), the 1-10 blocks of the plan are hot roll materials and transition materials, the 11-66 blocks are electrogalvanized products, and the 67-80 blocks are general low-carbon mild steel. This function is used when the plan is produced.

[0138] (2) The working rolls were replaced before the planned production, and the rolling process was set according to the procedure table after rolling started (tech_flag = 0).

[0139] (3) During the planned production process, the oxide film on the roll surface began to change, and the surface instrument collected the roll scale. The collected data results were used to determine the "roll scale grade on the strip surface" according to the "roll scale defect classification table", and the rolling process strategy was formulated based on the "hot rolling process strategy".

[0140] Strip steel surface quality and adopted technology

[0141]

[0142] According to the above rolling strategy, the defects of roll iron sheets were contained and no roll iron sheet blockade occurred in the plan.

[0143] Embodiment 2:

[0144] (1) For a certain pickling plate plan, the first 1-10 rolls of the plan are hot roll materials and transition materials, the 11th to 59th rolls are general low carbon soft steel, and the 60th to 75th rolls are pickling thin specifications of 2.1-1.6 mm.

[0145] (2) The working rolls were replaced before the planned production, and the rolling process was set according to the procedure table after rolling started (tech_flag = 0).

[0146] (3) During the planned production process, the oxide film on the roller surface began to change. The surface quality was collected by the surface instrument, and the "grade of the roller scale on the strip surface" was determined according to the "roller scale defect classification table". The rolling process application strategy was formulated based on the "hot rolling process strategy".

[0147] Strip steel surface quality and adopted technology

[0148]

[0149]

[0150] According to the above rolling strategy, through the adjustment of the rolling process, after the iron scale of the low-carbon soft steel roll system was graded as 2, the online dynamic adjustment of the rolling process was started, and the roll surface did not deteriorate further; after rolling to the pickled plate with higher surface requirements, the iron scale of the roll system on the strip surface was still under control, and the phenomenon of reaching the surface grade of the roll system iron scale of 4 did not occur in the entire plan.

[0151] The present invention is an online process adjustment method based on the classification of hot rolling roll iron scale. The online adjustment of the process is realized by establishing an adaptive method. The method does not need to stop the machine, thereby improving the production efficiency. The online adjustment of the present invention takes into account the stability of the rolling process and effectively suppresses and improves the generation of strip steel roll iron scale defects without destroying the rolling stability.

[0152] In summary, the present invention effectively improves the surface quality of the strip by online adjustment of the rolling process while ensuring the rolling stability, as follows:

[0153] 1. The present invention follows the hot rolling process principle of giving priority to ensuring rolling stability, and only adjusts the relevant process when the surface quality deteriorates. It not only ensures rolling stability, but also effectively suppresses and improves the generation of iron scale defects in the strip roll system through the adjustment of the rolling process.

[0154] 2. The present invention confirms the defect level according to the iron scale level of the roll system on the surface of the strip and the number of defects, realizes the online dynamic adjustment of the rolling process, and further improves the efficiency of the rolling process in improving the surface quality of the strip.

Claims

1. A process online adjustment method based on hot rolling roll iron sheet classification, characterized in that The steps include: S1: L2 determines the degree of defects of the roll iron scale and counts the corresponding number of defects based on the real-time strip surface map; S2: Determine the level of roll sheet defects according to the determination of the roll sheet defect category and the corresponding number of defects counted; S3: Establishing process adjustment for the current strip according to the determination of the level of the iron scale defect of the roll system of the previous strip; The process online adjustment method establishes adaptive dynamic adjustment of the process through the above steps. The process adjustment in step S3 is completed by adjusting the process factors corresponding to the main influencing factors of the roll iron sheet; in, The process factors are arranged in descending order according to their relevance to the roll iron sheet. The corresponding adjustment is formed by establishing a corresponding relationship between a process factor sequence with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale; The main factors affecting the roll iron sheet are the finishing load and the intermediate billet temperature. The process factors corresponding to the factors affecting the finishing rolling load are: the load distribution of finishing rolling itself, the thickness of the intermediate billet and the cooling of the rolls; The process factors corresponding to the influencing factors of the intermediate billet temperature are: the number of rough rolling dephosphorization passes; The order of decreasing relevance is formed, specifically: First relevance: load distribution of the finishing mill F2 and F3 stands; Second relevance: intermediate billet thickness; The third relevance: roller cooling and rough rolling dephosphorization pass, The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically: The levels of defects of the roll iron sheets are from low to high: level 1 defect, level 2 defect, level 3 defect, and level 4 defect; When it is a level 1 defect, no adjustment is made to the process factors; When it is a level 2 defect, the adaptation is established by adjusting the load distribution of the finishing mill F2 and F3 stands of the first relevance; When it is a level 3 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance and adjusting the thickness of the intermediate billet of the second relevance; When it is level 4 defect, adaptation is established by adjusting the load distribution of the finishing rolling F2 and F3 stands of the first relevance, the intermediate billet thickness of the second relevance, and the roll cooling and rough rolling dephosphorization passes of the third relevance.

2. The process online adjustment method based on hot rolling roll iron sheet classification according to claim 1 is characterized by: The corresponding adjustment is formed by establishing a corresponding relationship between a sequence of process factors with decreasing correlation with the roll iron scale and the level of defects of the roll iron scale, specifically: The regulation is established in a one-to-one correspondence with the order of the iron sheet defect levels of the rolling mill system from low to high in a manner of successively accumulating and increasing regulation of the process factor sequence with decreasing relevance to the rolling mill system.

3. The process online adjustment method based on hot rolling roll iron scale classification according to claim 1 is characterized in that: The degree of defects in the roll iron sheet is classified into Class 1, Class 2 and Class 3 from light to heavy according to the uniformity and peeling degree of the oxide film on the roll surface.

4. The process online adjustment method based on hot rolling roll iron scale classification according to claim 1 is characterized in that: The level of roll sheet defects is determined based on the determination of the roll sheet defect category and the corresponding number of defects counted, specifically: If the defect level is Class 1 and no defect points are detected, or if the defect level is Class 2 and the number of defect points counted ∈ [0,20], the defect level is set to Class 1; If the defect level is 2 and the number of defect points is ∈[21,50], or if the defect level is 3 and the number of defect points is ∈[0,10], the defect level is set to 2; If the defect level is 2 and the number of defect points is ∈ [51,200], or if the defect level is 3 and the number of defect points is ∈ [11,30], the defect level is set to level 3; If the defect level is Class 2 and the number of defect points counted exceeds 201, or if the defect level is Class 3 and the number of defect points counted ∈ [31, 100], the defect level is set to Class 4; When the defect level is Category 3 and the number of defect points counted exceeds 101, the defect level is set to Level 5, which corresponds to stopping the machine for roller replacement.

5. The process online adjustment method based on hot rolling roll iron scale classification according to claim 1 is characterized in that: The real-time strip steel surface map is acquired by using a CCD camera arranged on the detection bridge frame in combination with lighting to complete image acquisition or by using a surface meter to measure.

6. The process online adjustment method based on hot rolling roll iron scale classification according to claim 1 is characterized in that: The load adjustment for the finishing rolling F2 and F3 stands is as follows: when there is a second-level defect, the load is reduced by 2.8%~3.2%; when there is a third-level defect or a fourth-level defect, the load is reduced by 4.8%~5.2%; The specific adjustment of the intermediate billet thickness is: minus 2.8mm~3.2mm; The specific adjustment of the rough rolling dephosphorization passes is: reduce one set of passes.

7. The process online adjustment method based on hot rolling roll iron scale classification according to claim 1 is characterized in that: The roller cooling is achieved by adding a regulating valve to the original cooling water supply pipeline. When the defect is level 4, the water flow rate is increased by 9.8% to 10.2%.

Images