CN116408348A - Production method for preventing ultrathin high-carbon T5 material from breakage - Google Patents
Production method for preventing ultrathin high-carbon T5 material from breakage Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 72
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 34
- 238000005096 rolling process Methods 0.000 claims abstract description 157
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 63
- 239000010959 steel Substances 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims abstract description 34
- 238000004080 punching Methods 0.000 claims abstract description 32
- 238000009826 distribution Methods 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 16
- 238000009966 trimming Methods 0.000 claims abstract description 15
- 238000005098 hot rolling Methods 0.000 claims abstract description 14
- 230000007704 transition Effects 0.000 claims abstract description 13
- 238000003825 pressing Methods 0.000 claims abstract description 12
- 230000006835 compression Effects 0.000 claims abstract description 10
- 238000007906 compression Methods 0.000 claims abstract description 10
- 239000002994 raw material Substances 0.000 claims abstract description 10
- 238000005457 optimization Methods 0.000 claims abstract description 4
- 238000003466 welding Methods 0.000 claims description 22
- 239000002253 acid Substances 0.000 claims description 17
- 230000009467 reduction Effects 0.000 claims description 11
- 239000013072 incoming material Substances 0.000 claims description 6
- 238000013461 design Methods 0.000 claims description 4
- 230000009191 jumping Effects 0.000 claims description 4
- 230000002265 prevention Effects 0.000 claims description 3
- 239000003575 carbonaceous material Substances 0.000 claims 3
- 230000007547 defect Effects 0.000 description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 238000005482 strain hardening Methods 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 238000005097 cold rolling Methods 0.000 description 6
- 230000000630 rising effect Effects 0.000 description 6
- 238000005261 decarburization Methods 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 230000000881 depressing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000035553 feeding performance Effects 0.000 description 2
- 238000004886 process control Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
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Abstract
The invention relates to a production method for preventing an ultrathin high-carbon T5 material from being broken, which comprises the following steps: step 1, designing a compression ratio, and adopting different hot rolling raw material thicknesses according to a full-flow optimization principle aiming at different outlet thicknesses; step 2, planning and arranging a production plan reasonably according to the steel grade transition, the outlet width and the thickness of the strip steel; step 3, punching and trimming modes, wherein in the process of switching the gauge, the trimming and trimming modes are adjusted in advance according to different steel grades of the strip steel; step 4, presetting a model, namely presetting model pressing distribution and tension in advance according to the characteristic of high-strength high-difficulty rolling of a high-carbon T5 material; and 5, in the plate shape control mode, according to the state that the actual rolling force of the high-carbon T5 material is high, reasonably setting a plate shape control target curve to ensure the quality of the edge.
Description
Technical Field
The invention relates to a production method, in particular to a production method for preventing ultrathin high-carbon T5 material from breakage, and belongs to the technical field of cold rolling.
Background
In order to meet market demands, a certain iron and steel enterprise balances the quality of a steelmaking hot rolling process and the stability of continuous annealing tinning performance, an extremely thin high-carbon T5 is developed, the carbon content reaches 0.115-0.145%, the brand MR-T5 is provided, the conventional T5 carbon content is 0.005-0.008%, the rolling difficulty is determined by the known carbon content, and further the cold rolling stability and the rolling speed are influenced. Referring to fig. 1, when the existing 5-frame 6-roller UCM cold tandem mill rolls extremely thin high-carbon T5 strip steel, the actual rolling force in a low-speed area is abnormally increased, so that the edge cracks of the rolled strip steel are abnormally dense, the crack length reaches more than 10mm when the edge cracks of the strip steel at the outlet of the mill are serious, batch quality repair loss can be caused, the outlet of the mill breaks, and meanwhile, the edge cracks are more easily rolled out at the punching or trimming positions of the strip steel weld joint to break the strip steel; if the strip breakage occurs, the rolling state of the production line is further deteriorated due to the fact that the rolling mill has no transition hot roll material after the new roll is replaced, the quality is uncontrollable, and the stable operation and the capacity exertion of the acid rolling production line are seriously affected. Therefore, in order to meet the market demand, development of a production method for preventing breakage of the extremely thin high-carbon T5 material is urgently needed.
The method for preventing the edge of the cold-rolled steel strip from cracking is provided by searching the publication CN 106269860B, and comprises the following steps: sequentially carrying out pickling and rolling treatment on steel; wherein, the stretching elongation rate in the stretching and uncoiling process is reduced to 50% of the conventional stretching elongation rate in the pickling process, the concentration of pickling solution is increased by 5-10 g/L on the conventional concentration, and the pickling speed is reduced to 70% of the conventional speed; the elongation of the tension leveler is 1 to 5 percent; the gauge concentration is 120 g/L-170 g/L; the speed is 120 m/min-170 m/min. Five-pass rolling is performed, namely five frames are adopted for rolling, wherein the rolling reduction of the first-pass rolling is more than 40% of the total rolling reduction, and the rolling reduction of the second-pass rolling is more than 30% of the total rolling reduction. When rolling, a load distribution rolling strategy of pressing layering is realized by adopting large rolling force and large rolling pressure, and the load distribution of the first two frames is set to be more than 70% of the total rolling pressure: the load distribution of the first frame is increased to more than 40% of the total reduction, and layering defects caused by decarburization of rolling pressure-reduced raw materials of the first frame are fully pressed; increasing the load distribution of the second frame to more than 30% of the total reduction, and consolidating the pressing effect by utilizing the rolling pressure of the second frame; the load distribution of the rear three frames is automatically set according to the rolling model of the second-stage process computer, and the shape and thickness control precision of the finished strip steel are ensured. For example, the load distribution of the automatic setting of the rolling model of the secondary process computer is respectively as follows: 30%,25%,20%,15%,10%, then under this rolling strategy, it is necessary to manually modify the load distribution in the secondary process control interface to: 43%,32%, and then the second-stage process computer rolling model automatically calculates the load distribution of the three rear frames according to a certain rolling load distribution principle, for example, 13%,8% and 4% respectively. In the rolling process, a tension setting strategy of micro-tensile stress between the front frames is adopted, and the first-pass rolling and the second-pass rolling are adopted, namely, a micro-tension set value is adopted between the 1 st frame and the 2 nd frame, so that the tensile stress born by strip steel between the 1 st frame and the 2 nd frame is reduced, and the strip steel between the 1 st frame and the 2 nd frame is ensured not to generate edge crack defects at positions with decarburization defects due to larger tensile stress; and a conventional tension set value is adopted between the subsequent frames, so that the phenomenon of deviation of thinner strip steel between the subsequent frames is avoided. The micro tension value is 80N/mm 2-100N/mm 2.
The patent application publication No. CN 110125190A discloses a method and a device for preventing strip steel rolling edge cracking, and relates to the technical field of steel rolling, wherein the method comprises the following steps: carrying out hot rolling coiling according to coiling temperature control in a groove type coiling temperature change curve to obtain multi-coil strip steel; when a cold-rolled strip head and a cold-rolled strip tail which are connected by welding the two adjacent coiled strip steels are rolled by a cold continuous rolling mill, the tension between the racks is improved; when the welding line and the first preset area of the former strip steel and the second preset area of the latter strip steel which are connected by the welding line are rolled by the cold continuous rolling mill, the positive bending roller force of each rack of the cold continuous rolling mill is improved; controlling the coiled strip steel to be continuously rolled through a cold continuous rolling mill; reduces the welding line and the rolling edge crack near the welding line, avoids the occurrence of accidents such as strip breakage, improves the quality of strip steel products, and solves the technical problem that the edge crack defect exists near the welding line of the strip steel after cold continuous rolling in the prior art. Tension between the first rack and the second rack of the five-rack tandem rolling mill and the tension between the second rack and the third rack of the five-rack tandem rolling mill are 40%; the tension between the third and fourth frames and the fourth and fifth frames of the five-frame tandem continuous rolling mill is improved by 30 percent.
The main differences between the above-mentioned published patents and the present technology are: the patent publication CN 106269860B discloses that, regarding the edge crack defect caused by uneven deformation of the raw material edge with local decarburization, it means that the edge crack is generated correspondingly after rolling due to the defect of the local part of the incoming material, the measure is to reduce the elongation of the withdrawal and the tension corresponding to the increase of the load of 1 and 2 frames, and the mode of micro tension is adopted to prevent or reduce the delamination and the expansion of the micro crack at the local decarburization of the raw material due to the large tension, and the delamination defect caused by decarburization of the raw material due to the rolling pressure drop of the 1 st and 2 frames is sufficiently pressed to avoid the tension from pulling out the edge crack at the defect position. The research of the published patent CN 110125190A is to consider the change of the hot rolling temperature along with the coiling of the strip steel, avoid the crack generated near the welding line during the subsequent rolling caused by the temperature difference, take the hot rolling and coiling according to the coiling temperature control in the groove type coiling temperature change curve by the measure, obtain multi-coil strip steel, increase the tension and the bending force between frames when the welding line area is rolled by a cold continuous rolling mill when the welding line formed by welding two adjacent coil strips and the cold rolling band head and the cold rolling band tail connected by the welding line are rolled by the cold continuous rolling mill, and obtain the specific value range of the tension and the bending force by test, thereby reducing the rolling edge crack near the welding line and the welding line.
The invention provides an edge breakage prevention method suitable for stable rolling of an extremely-thin high-carbon T5 material based on an actual on-site rolling state, which aims at solving the problems of strip breakage at a rolling mill outlet caused by large deformation amount and high rolling force of the high-carbon extremely-thin T5 material in a cold rolling process and continuous edge breakage of the whole strip steel, and adopts a micro-edge rolling method to effectively prevent unstable quality production caused by rising rolling force in the rolling process, and has different directions and adopted method means compared with the research directions of the disclosed technology.
Disclosure of Invention
The invention provides a production method for preventing strip breakage of an ultrathin high-carbon T5 material, which aims at the problems existing in the prior art, solves the problem of stable rolling of the ultrathin high-carbon T5 material, solves the quality problems of edge cracking and the like of strip steel in the continuous rolling process, and avoids strip breakage and stop at an outlet of a rolling mill. Based on the on-site rolling state, a prevention and control method suitable for stable rolling of extremely thin high-carbon T5 materials is provided, the method is characterized in that planned arrangement, rolling preparation and model process adjustment are carried out in advance, a micro-edge wave rolling method is adopted, the occurrence of unstable production caused by rising rolling force in the rolling process is prevented, and the on-site use effect is obvious.
In order to achieve the above purpose, the technical scheme of the invention is as follows, and the production method for preventing the breakage of the ultrathin high-carbon T5 material is characterized by comprising the following steps:
step 2, planning and arranging a production plan reasonably according to the steel grade transition, the outlet width and the thickness of the strip steel;
step 3, punching and trimming modes, wherein in the process of switching the gauge, the trimming and trimming modes are adjusted in advance according to different steel grades of the strip steel;
step 4, presetting a model, namely presetting model pressing distribution and tension in advance according to the characteristic of high-strength high-difficulty rolling of a high-carbon T5 material;
and 5, in the plate shape control mode, according to the state that the actual rolling force of the high-carbon T5 material is high, reasonably setting a plate shape control target curve to ensure the quality of the edge.
As an improvement of the invention, the design of the compression ratio in step 1 is specifically as follows, the thickness of the outlet of the high-carbon T5 material acid rolling mill in the acid continuous rolling process is 0.17-0.3mm, and the design of the compression ratio is as follows: the outlet thickness h of the rolling mill is less than 0.25mm, the hot rolling incoming material is 2.0mm, h is more than or equal to 0.25 and less than or equal to 0.3, and the hot coil is 2.2mm. The thicker the incoming material is, the larger the deformation is, the higher the rolling difficulty is, the thickness of 1.8mm belongs to the hot rolling limit thickness, the temperature plate shape control in the production process is unstable, and the quality defects such as plate shape defect, edge defect and the like are easy to occur after acid rolling and rolling are caused.
As an improvement of the invention, step 2, planning and arrangement, specifically, the following is the following high carbon T5 material planning and arrangement requirements in the acid continuous rolling process: the backup roll is replaced, the scheduled rolling thickness is required to be more than or equal to 0.25mm transition material 1500 tons, and the production of high-carbon T5 materials with the thickness less than or equal to 0.20mm is not allowed within 8 hours, and in one skip roll replacement period, 2 groups of high-carbon T5 materials with the specification less than 0.18mm are not exceeded, each group of materials is provided with 2 similar-specification T4 roll replacement transition materials, and 2T 4+ 10T 5 materials.
As an improvement of the invention, the punching and edge punching mode of step 3 is specifically as follows, in order to ensure that the welded seam passing below 0.2mm is stable, the strip breakage of the welded seam is avoided in the acid continuous rolling process, when the high-carbon T5 material is produced, the welding machine adopts a non-punching mode, when T4 and T5 with the thickness of 0.2mm or below of the outlet of the rolling mill jump, if the width of the disc shear with the variable specification needs edge punching, the disc shear is punched on the jumping T4 material, and the strip breakage caused by edge punching and edge punching is avoided.
As an improvement of the invention, step 4, model presetting, concretely as follows,
in the production process of the high-carbon T5 material in the acid continuous rolling process, the load distribution of a 1-5 frame is optimized, the work hardening degree is improved, and the actual rolling force is reduced. The optimal range of the 1-5 machine frame distribution is 41% -44%, 42% -46%, 34% -38%, 32% -35% and 31% -34% respectively. Under the condition of certain material feeding performance and total deformation, the larger the deformation of the front frame is, the load of the rear frame can be reduced, but the larger the work hardening degree of the material is, the larger the rolling force is, and defects are easily formed. The practice that the deformation rate of the traditional 1-2 stand is larger is better, the traditional practice is verified by field test that the traditional 1-2 stand is not suitable for rolling high-carbon T5 materials with the specification below 0.2mm, the traditional 1-5 stand is required to reasonably distribute loads for rolling high-carbon T5 materials with the specification below 0.2mm, the abnormal rising of actual rolling force can be improved, the rolling rate of the traditional 1-2 stand is mainly reduced, the rolling rate of the traditional 4-5 stand is improved, the rolling rate of the traditional 4-2 stand is improved to 32-35%, the rolling rate of the traditional 5 stand is improved to 31-34%, the rolling rate of the traditional 4-stand is required to be about 1% higher than that of the traditional 5 stand, so that the outlet thickness of the front stand is increased, the deformation resistance of the front stand is reduced, the degree of work hardening of the strip steel on the front several stands is lightened, the actual rolling force is reduced, and the quality of the strip steel is improved.
The rolling reduction rate of the last frame is increased, the phenomenon that the rolling force is higher in the last frame, namely the fifth frame, is inevitable along with the rising of the load, in order to avoid the phenomenon that the 5 th frame of the extremely thin high-carbon T5 material is broken due to overlarge rolling force, the compensation coefficient of an additional tension model is increased, the compensation coefficient is adjusted to be 1.3 according to the outlet tension of a specific frame, namely 30 percent of the additional tension value calculated by the model is increased, the actual rolling force of the 5 th frame of a low-speed section can be reduced by increasing the additional tension, and the additional tension model is used for calculating the tension compensation of different speed sections of the strip steel so as to offset the change of the rolling force at different speeds, so that the strip steel has good plate shape and thickness at each speed section; the maximum speed at which the additional tension acts is 75% of the main speed of the rolling mill, if the main speed of the rolling mill is set to 1700mpm at the maximum, the maximum speed at which the additional tension acts is 1275mpm, and the speed section is divided into 5 sections equally according to the threading speed (50 mpm) to 75% of the maximum speed, so that a corresponding set value of the additional tension per unit is provided for each speed section. For example, a 0.18 x 835mm high carbon T5, after a 4/5 frame add-on tension factor compensation of 30%, it can be calculated that the 4/5 frame add-on tension increases from 14.1kg/mm2 to 18.33kg/mm2 at shear rate (at 200 mpm).
As an improvement of the invention, the step 5 and the plate shape control mode are specifically as follows, adopting a micro-edge wave rolling scheme, reducing rolling force in the step 4 increases an additional tension compensation coefficient, if the plate shape control of the edge part of the strip steel is too tight, edge part cracks are easily pulled out when the tensile stress is larger, and thus the edge part stress is increased and pulled out to cause edge cracks. Therefore, when rolling is expected to generate micro double-sided waves, namely a so-called loose edge rolling scheme is adopted, so as to prevent strip breakage accidents caused by edge cracks, a 5-frame strip shape closed loop control adopts a micro-sided wave strip shape control mode to optimize a strip shape target curve, the strip steel edge tensioning phenomenon is improved, the strip shape target curve is a target of strip shape control, in the strip shape control process, an actual strip shape curve is controlled to the target curve, the difference between the strip shape and the target curve is eliminated as far as possible, in a secondary system, the target curve is a parameter setting method, the target curve is determined by three parameters a, b and c, and the target curve stored in the secondary system is the target curve set by the parameter setting method;
the final target curve actually used in the field in step 5 is:
compared with the prior art, the invention has the following advantages that 1, the invention solves the problem of outlet broken belt caused by edge crack at punching and trimming when welding seams are crossed by adopting a mode that the welding seams are not punched and trimming is carried out on the material T4 when the specification T4/T5 is changed; 2. the invention reduces the distribution of the rolling ratios of the frames 1 and 2, improves the rolling ratios of the frames 4 and 5, and requires that the rolling ratio of the frames 4 is about 1 percent higher than that of the frames 5, thereby increasing the outlet thickness of the frame in front, reducing the deformation resistance of the band steel of the frame in front, reducing the degree of work hardening of the band steel in the frame in front, simultaneously adding tension compensation coefficients to the frames 4 and 5, improving the fluctuation range of the actual rolling force of the frames 4 and 5, reducing the fluctuation of the actual rolling force, improving the quality of the edge and improving the control precision of the plate thickness of the band steel. 3. The strip shape control system aims at the problem that edge cracks are pulled out when tensile stress is large due to overtightening of strip steel edge shape control by adopting a control mode of micro-edge waves, so that the occurrence of rolling edge cracks is effectively controlled; 4. the method can be completed through a production line process control computer without adding additional data acquisition equipment.
Drawings
FIG. 1 is a schematic diagram of a five stand mill process.
In the figure: 1-band steel, 2-tension roller, 3-NO1 rack, 4-NO2 rack, 5-NO3 rack, 6-NO4 rack, 7-NO5 rack, 8-crimping machine, 9-supporting roller, 10-intermediate roller and 11-working roller.
The specific embodiment is as follows:
in order to enhance the understanding of the present invention, the present embodiment will be described in detail with reference to the accompanying drawings.
Example 1: referring to fig. 1, a production method for preventing breakage of an extremely thin high carbon T5 material, the method comprising the steps of:
step 2, planning and arranging a production plan reasonably according to the steel grade transition, the outlet width and the thickness of the strip steel;
step 3, punching and trimming modes, wherein in the process of switching the gauge, the trimming and trimming modes are adjusted in advance according to different steel grades of the strip steel;
step 4, presetting a model, namely presetting model pressing distribution and tension in advance according to the characteristic of high-strength high-difficulty rolling of a high-carbon T5 material;
and 5, in the plate shape control mode, according to the state that the actual rolling force of the high-carbon T5 material is high, reasonably setting a plate shape control target curve to ensure the quality of the edge.
Step 2, planning, namely, the following high-carbon T5 material planning in the acid continuous rolling process is required: the backup roll is replaced, the scheduled rolling thickness is required to be more than or equal to 0.25mm transition material 1500 tons, and the production of high-carbon T5 materials with the thickness less than or equal to 0.20mm is not allowed within 8 hours, and in one skip roll replacement period, 2 groups of high-carbon T5 materials with the specification less than 0.18mm are not exceeded, each group of materials is provided with 2 similar-specification T4 roll replacement transition materials, and 2T 4+ 10T 5 materials.
And 3, punching and edge punching modes, namely, in the acid continuous rolling process, in order to ensure that a plate is stably passed through a welding seam of less than 0.2mm, avoiding the broken belt of a welding seam during punching, adopting a non-punching mode by a welding machine during production of high-carbon T5 materials, and punching on a jumping T4 material when T4 and T5 with the thickness of 0.2mm or less at the outlet of a rolling mill jump, if the disc shears with the width of changing specifications need edge punching, and avoiding edge breaking belt during punching and edge punching.
Step 4, presetting a model, specifically as follows,
in the production process of the high-carbon T5 material in the acid continuous rolling process, the load distribution of a 1-5 frame is optimized, the work hardening degree is improved, and the actual rolling force is reduced. The optimal range of the 1-5 machine frame distribution is 41% -44%, 42% -46%, 34% -38%, 32% -35% and 31% -34% respectively. Under the condition of certain material feeding performance and total deformation, the larger the deformation of the front frame is, the load of the rear frame can be reduced, but the larger the work hardening degree of the material is, the larger the rolling force is, and defects are easily formed. The practice that the deformation rate of the traditional 1-2 stand is larger is better, the traditional practice is verified by field test that the traditional 1-2 stand is not suitable for rolling high-carbon T5 materials with the specification below 0.2mm, the traditional 1-5 stand is required to reasonably distribute loads for rolling high-carbon T5 materials with the specification below 0.2mm, the abnormal rising of actual rolling force can be improved, the rolling rate of the traditional 1-2 stand is mainly reduced, the rolling rate of the traditional 4-5 stand is improved, the rolling rate of the traditional 4-2 stand is improved to 32-35%, the rolling rate of the traditional 5 stand is improved to 31-34%, the rolling rate of the traditional 4-stand is required to be about 1% higher than that of the traditional 5 stand, so that the outlet thickness of the front stand is increased, the deformation resistance of the front stand is reduced, the degree of work hardening of the strip steel on the front several stands is lightened, the actual rolling force is reduced, and the quality of the strip steel is improved.
The rolling reduction rate of the last frame is increased, the phenomenon that the rolling force is higher in the last frame, namely the fifth frame, is inevitable along with the rising of the load, in order to avoid the phenomenon that the 5 th frame of the extremely thin high-carbon T5 material is broken due to overlarge rolling force, the compensation coefficient of an additional tension model is increased, the compensation coefficient is adjusted to be 1.3 according to the outlet tension of a specific frame, namely 30 percent of the additional tension value calculated by the model is increased, the actual rolling force of the 5 th frame of a low-speed section can be reduced by increasing the additional tension, and the additional tension model is used for calculating the tension compensation of different speed sections of the strip steel so as to offset the change of the rolling force at different speeds, so that the strip steel has good plate shape and thickness at each speed section; the maximum speed at which the additional tension acts is 75% of the main speed of the rolling mill, if the main speed of the rolling mill is set to 1700mpm at the maximum, the maximum speed at which the additional tension acts is 1275mpm, and the speed section is divided into 5 sections equally according to the threading speed (50 mpm) to 75% of the maximum speed, so that a corresponding set value of the additional tension per unit is provided for each speed section. For example, a 0.18 x 835mm high carbon T5, after a 4/5 frame add-on tension factor compensation of 30%, it can be calculated that the 4/5 frame add-on tension increases from 14.1kg/mm2 to 18.33kg/mm2 at shear rate (at 200 mpm).
And 5, adopting a micro-edge wave rolling scheme, wherein the rolling force is reduced in the step 4, the additional tension compensation coefficient is increased, and if the strip steel edge shape is controlled to be too tight, edge cracks are easily pulled out when the tensile stress is larger, so that the edge stress is increased, and the edge cracks are pulled out. Therefore, when rolling is expected to generate micro double-sided waves, namely a so-called loose edge rolling scheme is adopted, so as to prevent strip breakage accidents caused by edge cracks, a 5-frame strip shape closed loop control adopts a micro-sided wave strip shape control mode to optimize a strip shape target curve, the strip steel edge tensioning phenomenon is improved, the strip shape target curve is a target of strip shape control, in the strip shape control process, an actual strip shape curve is controlled to the target curve, the difference between the strip shape and the target curve is eliminated as far as possible, in a secondary system, the target curve is a parameter setting method, the target curve is determined by three parameters a, b and c, and the target curve stored in the secondary system is the target curve set by the parameter setting method;
the final target curve actually used in the field in step 5 is:
specific example 1:
taking a tin-plated substrate with the thickness specification of 0.2mm, the width specification of 1047mm and the brand MR T-5CA as an outlet of a rolled product of a certain iron and steel enterprise, and taking T4 material production with the thickness of 0.2mm and the width of 972mm as a rear strip steel as an example; specific embodiments of this patent are described.
1. The thickness specification of the product outlet is 0.2mm, and the thickness of the product outlet is 2.0mm corresponding to the hot rolling raw material;
2. scheduling production after 2 shifts of the supporting roller, and simultaneously scheduling 2T 4 roller changing transition materials with the same thickness specification;
3. the T5 material welding machine adopts a non-punching mode, and when the T5 and the T4 are in a variable specification, the punching edge of the circular shears punches on the jumping T4 material;
4. model presetting: the 1-5 frames are distributed under the pressing condition, the 1-2 frames are adopted to reduce the pressing ratio, the 4-5 frames are improved, the 4 frames are improved from the conventional 27-29% to 32-35%, the 5 frames are improved from the conventional 28-30% to 31-34%, and the 4 frames are required to have the pressing ratio which is about 1% higher than that of the 5 frames. The specific set values are shown in Table 1.
Table 1: depressing the dispensing setting
| Rack number | An |
1 | 2 | 3 | 4 | 5 |
| Thickness mm | 2.0 | 1.177 | 0.682 | 0.446 | 0.299 | 0.2 |
| Reduction percentage% | 41.1 | 42 | 34.7 | 32.9 | 31.4 |
The values of each velocity segment obtained by the calculation model after compensation of the additional tension coefficient are shown in table 2 below.
Table 2: additional tension calculation result
5. Setting a micro-edge wave control plate-shaped target curve: three parameters a= -2, b= -1 and c=0 which are set by the steel grade, width and thickness grade in the two-stage setting table and correspond to the target curve are issued to the first stage, and the actual target curve is obtained after calculation by the first-stage target curve program, wherein the actual target curve is as follows:
spref＝-2x 2 。
specific example 2:
the specific implementation mode of the patent is introduced by taking a tin-plated substrate with the thickness specification of 0.171mm, the width specification of 912mm and the trademark MR T-5CA of an outlet of a cold-rolled product of a certain iron and steel enterprise and taking the same specification production as the front and back as an example.
1. The thickness of the hot rolled raw material with the thickness specification of 0.171mm is 2.0mm,
2.2 same-specification T4 roll change transition materials are scheduled after the support roll is scheduled to be changed for 2 shifts, and at most 2 groups of 0.171mmT5 materials are scheduled in one jump period, wherein each group is smaller than 10;
3. the welding machine adopts a non-punching mode, and the same-specification circle shears do not need to punch edges;
4. model presetting: the 1-5 frames are distributed under the pressing condition, the 1-2 frames are adopted to reduce the pressing ratio, the 4-5 frames are improved, the 4 frames are improved from the conventional 27-29% to 32-35%, the 5 frames are improved from the conventional 28-30% to 31-34%, and the 4 frames are required to have the pressing ratio which is about 1% higher than that of the 5 frames. The specific set values are shown in Table 3.
Table 3: depressing the dispensing setting
| Rack number | An |
1 | 2 | 3 | 4 | 5 |
| Thickness mm | 2.0 | 1.137 | 0.625 | 0.393 | 0.256 | 0.171 |
| Reduction percentage% | 43.2 | 45.1 | 37.2 | 34.8 | 33.2 |
The values of each velocity segment obtained by the calculation model after compensation of the additional tension coefficient are shown in table 4 below.
Table 4: additional tension calculation result
| Speed section (mpm) | 50-356 | 356-662 | 662-968 | 968-1275 | 1275-1700 |
| Additional tension | 19.42 | 7.77 | 2.33 | 1.16 | 0 |
5. Setting a plate-shaped target curve: three parameters a=2, b=1 and c=0 which are set by the steel grade, width and thickness grade in the secondary setting table and correspond to the target curve are issued to the primary, and the actual target curve is obtained after calculation by a primary target curve program, wherein the actual target curve is as follows:
spref＝2x 2
counting the situation of strip breakage at the outlet of the rolling mill after cold rolling, it can be seen from Table 5 that the implementation of the new process significantly reduces the occurrence rate of strip breakage at the outlet of the rolling mill from 12.6% to 2.6%.
Table 5 statistical comparison of incidence of strip breakage at mill outlet
| Number of rolls | Number of belt breaks | Incidence/% | |
| Original technology | 175 | 22 | 12.6 |
| New technology | 152 | 4 | 2.6 |
It should be noted that the above-mentioned embodiments are not intended to limit the scope of the present invention, and equivalent changes or substitutions made on the basis of the above-mentioned technical solutions fall within the scope of the present invention as defined in the claims.
Claims (6)
1. A production method for preventing breakage of an ultrathin high-carbon T5 material, which is characterized by comprising the following steps:
step 1, designing a compression ratio, and adopting different hot rolling raw material thicknesses according to a full-flow optimization principle aiming at different outlet thicknesses;
step 2, planning and arranging a production plan reasonably according to the steel grade transition, the outlet width and the thickness of the strip steel;
step 3, punching and trimming modes, wherein in the process of switching the gauge, the trimming and trimming modes are adjusted in advance according to different steel grades of the strip steel;
step 4, presetting a model, namely presetting model pressing distribution and tension in advance according to the characteristic of high-strength high-difficulty rolling of a high-carbon T5 material;
and 5, in the plate shape control mode, according to the state that the actual rolling force of the high-carbon T5 material is high, reasonably setting a plate shape control target curve to ensure the quality of the edge.
2. The production method for preventing strip breakage of extremely thin high-carbon T5 material according to claim 1, wherein the design of the compression ratio in step 1 is specifically as follows, the thickness of the outlet of the high-carbon T5 material acid rolling mill in the acid continuous rolling process is 0.17-0.3mm, and the design of the compression ratio is as follows: the outlet thickness h of the rolling mill is less than 0.25mm, the hot rolling incoming material adopts 2.0mm, h is more than or equal to 0.25 and less than or equal to 0.3, and the hot coil adopts 2.2mm.
3. The production method for preventing strip breakage of extremely thin high-carbon material T5 as claimed in claim 2, wherein the planning and arrangement of step 2 is as follows, and the high-carbon material T5 in the acid continuous rolling process is as follows: the backup roll is replaced, the scheduled rolling thickness is required to be more than or equal to 0.25mm transition material 1500 tons, and the production of high-carbon T5 materials with the thickness less than or equal to 0.20mm is not allowed within 8 hours, and in one skip roll replacement period, 2 groups of high-carbon T5 materials with the specification less than 0.18mm are not exceeded, each group of materials is provided with 2 similar-specification T4 roll replacement transition materials, and 2T 4+ 10T 5 materials.
4. The method for producing the ultra-thin high-carbon T5 material strip breakage prevention according to claim 3, wherein the step 3 is a punching and edge punching mode, specifically comprising the following steps of punching and edge punching on a jumping T4 material to ensure that a welded seam is passed stably for less than 0.2mm in an acid continuous rolling process, avoiding strip breakage caused by welded seam punching, wherein a welding machine adopts a non-punching mode when the high-carbon T5 material is produced, and when T4 and T5 with the thickness of 0.2mm or less at an outlet of a rolling mill jump, if edge punching is required by a width-variable specification circle shear, avoiding strip breakage caused by edge punching and edge punching.
5. The method according to claim 3 or 4, wherein the step 4 is a model presetting, specifically, the rolling reduction of the last frame is increased, the compensation coefficient of the additional tension model is increased, the compensation coefficient is adjusted to 1.3 for the outlet tension of the specific frame, the additional tension compensation coefficient is increased by 30% based on the additional tension value calculated by the model, the additional tension is increased to reduce the actual rolling force of the 5 frames of the low speed section, the highest acting speed of the additional tension is 75% of the main speed of the rolling mill, if the main speed of the rolling mill is set to 1700mpm, the highest acting speed of the additional tension is 1275mpm, and the speed section is divided into 5 sections according to the average of 75% of the threading speed (50 mpm) to the maximum speed, thus the corresponding set value of the additional tension of unit is provided for each speed section.
6. The production method for preventing the strip breakage of the extremely thin high-carbon material T5 is characterized by comprising the following steps of 5, adopting a micro-edge wave rolling scheme, optimizing a strip-shaped target curve by adopting the micro-edge wave strip-shaped control mode for 5-frame strip-shaped closed-loop control, improving the strip steel edge tensioning phenomenon, wherein the strip-shaped target curve is a target of strip-shaped control, controlling an actual strip-shaped curve to the target curve in the strip-shaped control process, eliminating the difference between the strip-shaped target curve and the target curve, wherein the target curve in a secondary system is a parameter setting method, and is determined by three parameters a, b and c, wherein the target curve stored in the secondary system is a target curve set by the parameter setting method;
the final target curve actually used in the field in step 5 is:
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