A stainless steel strip breakage control method for an eighteen-high five-stand tandem cold rolling mill

Abstract

The present application belongs to the technical field of stainless steel cold rolling, and provides a kind of eighteen roll five machine frame cold continuous rolling mill stainless steel strip break control method, including control adjustment deformation and rolling force;Adjust the bending roll value of each rack to realize plate shape and edge drop control;When the width and thickness of stainless steel change, control the front slip value and tension fluctuation;When the weld passes through the continuous rolling mill, control the rolling at the weld;Finally, control the replacement of work roll;The present application controls the problem of large tension fluctuation caused by thickness, width change and parking start-up of stainless steel cold rolled strip during continuous rolling process through parameter setting and process adjustment of continuous rolling mill, reduces the strip break rate of continuous rolling mill, and ensures stable production operation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of stainless steel cold rolling and relates to a stainless steel strip breakage control method, in particular to a stainless steel strip breakage control method for an eighteen-roller five-stand continuous cold rolling mill. BACKGROUND

[0002] With the development of stainless steel cold rolling technology, the eighteen-roller continuous cold rolling mill is currently widely used in the field of stainless steel cold rolling. On the one hand, the strip breakage of the continuous rolling mill is the main cause of the production efficiency of the mill group. In the continuous cold rolling production of the stainless steel strip, due to the connection of the changes in the thickness and width of the raw material and the parking and starting process, the actual tension of the strip steel and the set tension have a large gap, and the tension is subjected to a sharp fluctuation when the weld passes through the rolling mill, which easily causes the tearing of the strip steel due to the excessive local force on the edge of the strip steel, thereby greatly affecting the continuous production of the continuous rolling mill. SUMMARY

[0003] The purpose of the application is to provide a stainless steel strip breakage control method for an eighteen-roller five-stand continuous cold rolling mill. The method controls the tension fluctuation of the stainless steel cold rolling strip caused by the changes in the thickness and width and the parking and starting process in the continuous rolling process through the parameter setting and process adjustment of the continuous rolling mill, thereby reducing the strip breakage rate of the continuous rolling mill and ensuring the stable operation of the production.

[0004] The technical solution adopted by the application to achieve the above purpose is:

[0005] A stainless steel strip breakage control method for an eighteen-roller five-stand continuous cold rolling mill, comprising:

[0006] S1, controlling the total deformation of rolling to be between 70% and 83% by adjusting the deformation and rolling force control;

[0007] S2, realizing the plate shape and edge drop control by adjusting the bending roll value of each stand;

[0008] S3, controlling the front slip value fluctuation when rolling the stainless steel with changes in the width and thickness;

[0009] S4, controlling the tension fluctuation when rolling the stainless steel with changes in the width and thickness;

[0010] S5, controlling the rolling at the weld when the weld passes through the continuous rolling mill;

[0011] S6, controlling the replacement of the work roll;

[0012] Further, the specific control method of S1 is:

[0013] When the rolling steel is ferrite stainless steel, the parameter setting of the 1# rack is that the deformation is 20-24%, and the rolling force is 6000-7000kN; the parameter setting of the 2# rack is that the deformation is 22-26%, and the rolling force is 6500-7500kN; the parameter setting of the 3# rack is that the deformation is 25-29%, and the rolling force is 6500-7500kN; the parameter setting of the 4# rack is that the deformation is 25-29%, and the rolling force is 5000-5500kN; and the parameter setting of the 5# rack is that the deformation is 14-18%, and the rolling force is 4000-4500kN.

[0014] When the rolling steel is austenitic stainless steel, the parameter setting of the 1# rack is that the deformation is 30-35%, and the rolling force is 9000-10000kN; the parameter setting of the 2# rack is that the deformation is 30-35%, and the rolling force is 10000-11000kN; the parameter setting of the 3# rack is that the deformation is 25-30%, and the rolling force is 11500-12500kN; the parameter setting of the 4# rack is that the deformation is 20-25%, and the rolling force is 10000-11000kN; and the parameter setting of the 5# rack is that the deformation is 20-25%, and the rolling force is 9000-10000kN.

[0015] When the width of the rolling austenitic stainless steel is greater than or equal to 1500mm, and the thickness is less than or equal to 1.0mm, the manual adjustment of the deformation of the 1# rack is less than 28%, which can effectively control the occurrence of the surface pinching defects of the strip steel and reduce the risk of the pinching break.

[0016] Further, the specific control method of S2 is that:

[0017] When the rolling steel is austenitic stainless steel, the parameter setting of the 1# rack is that the bending roll value is 82-86%, the parameter setting of the 2# rack is that the bending roll value is 47-51%, the parameter setting of the 3# rack is that the bending roll value is 49-53%, the parameter setting of the 4# rack is that the bending roll value is 52-56%, and the parameter setting of the 5# rack is that the bending roll value is 62-64%.

[0018] When the rolling steel is ferrite stainless steel, the parameter setting of the 1# rack is that the bending roll value is -70--66%, the parameter setting of the 2# rack is that the bending roll value is -15--10%, the parameter setting of the 3# rack is that the bending roll value is -5-0%, the parameter setting of the 4# rack is that the bending roll value is -50--45%, and the parameter setting of the 5# rack is that the bending roll value is 10-15%.

[0019] Further, the specific control method of S3 is that:

[0020] Under the normal rolling condition, the front slip value is required to be controlled between 0-1%, during the fluctuation process of the front slip value, the rolling speed is kept to be less than 50m / min, the time when the front slip value is less than 2% is less than or equal to 5s, otherwise the continuous rolling is immediately stopped.

[0021] Further, the specific control method of S4 is:

[0022] For the 5# rack unit tension rule setting: strip product thickness 0.8mm, 5# rack unit tension control in 190-220N / mm 2 ; strip product thickness 1.0mm, 5# rack unit tension control in 200-220N / mm 2 ; strip product thickness 1.2mm, 5# rack unit tension control in 200-220N / mm 2 ; strip product thickness 1.5mm, 5# rack unit tension control in 180-205N / mm 2 ; strip product thickness 2.0mm, 5# rack unit tension control in 175-195N / mm 2 ; strip product thickness 2.5mm, 5# rack unit tension control in 160-180N / mm 2 ; strip product thickness 3.0mm, 5# rack unit tension control in 155-175N / mm 2 ; when rolling 1.2mm or less ferritic stainless steel, 5# rack outlet unit tension is reduced to 200N / mm 2 , 220N / mm 2 , and then restored after stable;

[0023] The maximum width specification change is 400mm, and different tension control measures are formulated according to the transition width:

[0024] Width change 100mm, 5# rack outlet unit tension reduced by 25N / mm 2 ;

[0025] Width change 200mm, 5# rack outlet unit tension reduced by 30N / mm 2 ;

[0026] Width change 300mm, 5# rack outlet unit tension reduced by 35N / mm 2 ;

[0027] Width change 400mm, 5# rack outlet unit tension reduced by 40N / mm 2 ;

[0028] The maximum thickness specification change is not more than 0.5mm, and the 5# rack outlet unit tension is reduced by 40N / mm 2 when the thickness specification is transitioned, and the strip unit tension is reduced by 40N / mm 2 during the start-up process after stopping.

[0029] Further, the specific control method of S5 is that the welding seam adopts a semi-rolling mode when passing through the continuous rolling mill, the rolling force is reduced by 20%, the bending roll value is manually increased by 5-10%, and the mill is stopped and adjusted again when the deviation value exceeds 20 mm or more.

[0030] Further, the specific control method of S6 is that the front slip value is less than or equal to-0.5% for a long time, or the work roll is replaced when the plate shape is abnormal at the outlet of the 5# rack.

[0031] The beneficial effects of the present application are:

[0032] (1) improve production efficiency;

[0033] Reduce downtime, broken belt will cause production line downtime, and it takes a long time to handle the broken belt accident. Controlling the broken belt can significantly reduce the downtime and improve the operation rate; increase the yield, stabilize the production process, reduce the production interruption caused by the broken belt, enable the rolling mill to run continuously and efficiently, and improve the yield.

[0034] (2) reduce production cost;

[0035] Reduce scrap rate, scrap is generated by broken belt, controlling broken belt can reduce scrap rate and improve product yield; reduce roller consumption, broken belt often causes roller damage, controlling broken belt can reduce roller replacement frequency, reduce roller consumption and maintenance cost; reduce energy consumption, stabilize production and reduce energy waste, improve energy efficiency.

[0036] (3) improve product quality;

[0037] Ensure product size accuracy, broken belt often causes size deviation, controlling broken belt helps to maintain product size accuracy and meet customer requirements; improve surface quality, reduce surface defects caused by broken belt, such as scratches, indentations, etc.

[0038] (4) ensure equipment safety;

[0039] Reduce equipment damage, broken belt may cause equipment damage, controlling broken belt can prolong the service life of the equipment; reduce maintenance cost and reduce equipment maintenance frequency and cost. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Table of 304 stainless steel production parameters with a width of 1550 mm and a thickness of 4.5 mm. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application clearer, further detailed description of the present application is given. It should be understood that the specific embodiments and examples described herein are only used to explain the present application, and are not used to limit the present application.

[0042] A kind of stainless steel strip breakage control method of eighteen-roller five-stand cold continuous rolling mill, comprising:

[0043] S1, by adjusting the deformation and rolling force control, the total deformation of rolling control is between 70% and 83%;

[0044] When rolling ferritic stainless steel, the parameter setting of 1# rack is deformation: 20-24%, rolling force 6000-7000kN;The parameter setting of 2# rack is deformation: 22-26%, rolling force 6500-7500kN;The parameter setting of 3# rack is deformation: 25-29%, rolling force 6500-7500kN;The parameter setting of 4# rack is deformation: 25-29%, rolling force 5000-5500kN;The parameter setting of 5# rack is deformation: 14-18%, rolling force 4000-4500kN;

[0045] When rolling austenitic stainless steel, the parameter setting of 1# rack is deformation: 30-35%, rolling force 9000-10000kN;The parameter setting of 2# rack is deformation: 30-35%, rolling force 10000-11000kN;The parameter setting of 3# rack is deformation: 25-30%, rolling force 11500-12500kN;The parameter setting of 4# rack is deformation: 20-25%, rolling force 10000-11000kN;The parameter setting of 5# rack is deformation: 20-25%, rolling force 9000-10000kN;

[0046] When the width of rolling austenitic stainless steel is greater than or equal to 1500mm, and the thickness is less than or equal to 1.0mm, manually adjusting the deformation of 1# rack to less than 28% can effectively control the occurrence of strip surface printing defects and reduce the risk of strip breakage.

[0047] S2, by adjusting the bending roll value of each rack, the plate shape and edge drop control is realized;

[0048] When rolling austenitic stainless steel, the parameter setting of 1# rack is bending roll value 82-86%, the parameter setting of 2# rack is bending roll value 47-51%, the parameter setting of 3# rack is bending roll value 49-53%, the parameter setting of 4# rack is bending roll value 52-56%, and the parameter setting of 5# rack is bending roll value 62-64%;

[0049] When rolling ferritic stainless steel, the parameter setting of 1# rack is bending roll value-70--66%, the parameter setting of 2# rack is bending roll value-15--10%, the parameter setting of 3# rack is bending roll value-5-0%, the parameter setting of 4# rack is bending roll value-50--45%, and the parameter setting of 5# rack is bending roll value 10-15%.

[0050] S3, control the fluctuation of front slip value when the width and thickness of rolled stainless steel change;

[0051] Under normal rolling conditions, the front slip value is required to be controlled between 0-1%, during the fluctuation of front slip value, the rolling speed is maintained less than 50 m / min, the time of front slip value less than 2% is less than or equal to 5 s, otherwise the continuous rolling is immediately stopped.

[0052] S4, control the tension fluctuation when the width and thickness of rolled stainless steel change;

[0053] The unit tension of 5# rack is set according to the following rules: the finished product thickness of the strip steel is 0.8 mm, the unit tension of 5# rack is controlled between 190-220 N / mm 2 ; the finished product thickness of the strip steel is 1.0 mm, the unit tension of 5# rack is controlled between 200-220 N / mm 2 ; the finished product thickness of the strip steel is 1.2 mm, the unit tension of 5# rack is controlled between 200-220 N / mm 2 ; the finished product thickness of the strip steel is 1.5 mm, the unit tension of 5# rack is controlled between 180-205 N / mm 2 ; the finished product thickness of the strip steel is 2.0 mm, the unit tension of 5# rack is controlled between 175-195 N / mm 2 ; the finished product thickness of the strip steel is 2.5 mm, the unit tension of 5# rack is controlled between 160-180 N / mm 2 ; the finished product thickness of the strip steel is 3.0 mm, the unit tension of 5# rack is controlled between 155-175 N / mm 2 ; when rolling ferrite stainless steel below 1.2 mm, the unit tension of 5# rack outlet is reduced to 200 N / mm 2 from 220 N / mm 2 , and restored after stabilization;

[0054] The maximum width specification change is 400 mm, different tension control measures are set according to the transition width:

[0055] The width change is 100 mm, the unit tension of 5# rack outlet is reduced by 25 N / mm 2 ;

[0056] The width change is 200 mm, the unit tension of 5# rack outlet is reduced by 30 N / mm 2 ;

[0057] The width change is 300 mm, the unit tension of 5# rack outlet is reduced by 35 N / mm 2 ;

[0058] The width change is 400 mm, the unit tension of 5# rack outlet is reduced by 40 N / mm 2 ;

[0059] The maximum change in thickness specification shall not exceed 0.5mm. During the thickness specification transition, the unit tension at the exit of frame #5 shall be reduced by 40N / mm. 2 The unit tension of the strip steel will be reduced by 40 N / mm during the restart process after parking. 2 .

[0060] S5. Control the rolling process at the weld seam when the weld seam passes through the continuous rolling mill;

[0061] When the weld passes through the continuous rolling mill, a half-rolling mode is used to reduce the rolling force by 20%. The bending roll value is manually increased by 5-10%. If the deviation exceeds 20mm, the machine is stopped and then adjusted.

[0062] S6. Control of work roll replacement;

[0063] Replace the work roll when the forward slip value is less than or equal to -0.5% for an extended period or when abnormal plate shape occurs at the exit of frame #5.

[0064] Example 1

[0065] Producing 1550mm wide, 4.5mm thick 304 stainless steel, such as... Figure 1 Production is carried out according to the parameter table. After production is completed, production continues with 1350mm wide and 4.5mm thick 304 stainless steel. To ensure smooth rolling of the width transition section, the unit tension of the strip on stand #5 is reduced from 219N / mm. 2 Reduced to 189 N / mm 2 The rolling pressure of each stand is routinely adjusted according to the width variation.

[0066] The production process controls the large tension fluctuations of stainless steel cold-rolled strip during continuous rolling due to changes in thickness and width, as well as shutdowns and restarts, by setting parameters and adjusting processes of the continuous rolling mill. This reduces the strip breakage rate of the continuous rolling mill and ensures stable production operation.

[0067] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling stainless steel strip breakage in an 18-roll, 5-stand cold rolling mill, characterized in that: include: S1. By adjusting the deformation amount and rolling force control, the total rolling deformation amount is controlled between 70% and 83%. When rolling ferritic stainless steel, the parameters for stand #1 are set as follows: deformation rate: 20-24%, rolling force: 6000-7000 kN; for stand #2: deformation rate: 22-26%, rolling force: 6500-7500 kN; for stand #3: deformation rate: 25-29%, rolling force: 6500-7500 kN; for stand #4: deformation rate: 25-29%, rolling force: 5000-5500 kN; and for stand #5: deformation rate: 14-18%, rolling force: 4000-4500 kN. When rolling austenitic stainless steel, the parameters for stand #1 are set as follows: deformation rate: 30-35%, rolling force: 9000-10000kN; for stand #2, deformation rate: 30-35%, rolling force: 10000-11000kN; for stand #3, deformation rate: 25-30%, rolling force: 11500-12500kN; for stand #4, deformation rate: 20-25%, rolling force: 10000-11000kN; and for stand #5, deformation rate: 20-25%, rolling force: 9000-10000kN. When the width of the rolled austenitic stainless steel is ≥1500mm and the thickness is ≤1.0mm, manually adjusting the deformation of the No.1 stand to less than 28% can effectively control the occurrence of surface defects of the strip and reduce the risk of strip breakage. S2. Plate shape and edge drop are controlled by adjusting the bending roller values ​​of each frame. When rolling austenitic stainless steel, the parameters for stand #1 are set to a roll bending value of 82-86%, stand #2 to 47-51%, stand #3 to 49-53%, stand #4 to 52-56%, and stand #5 to 62-64%. When rolling ferritic stainless steel, the parameters for stand #1 are set to a roll bending value of -70-66%, stand #2 to a roll bending value of -15-10%, stand #3 to a roll bending value of -5-0%, stand #4 to a roll bending value of -50-45%, and stand #5 to a roll bending value of 10-15%. S3. Control the fluctuation of the forward slip value when the width and thickness of rolled stainless steel change. Under normal rolling conditions, the forward slip value should be controlled between 0-1%. During the fluctuation of the forward slip value, the rolling speed should be kept less than 50m / min, and the forward slip value should be less than 2% for less than or equal to 5s. Otherwise, continuous rolling should be stopped immediately. S4. Control tension fluctuations when the width and thickness of rolled stainless steel change; The unit tension rule for frame #5 is set as follows: with a finished strip thickness of 0.8mm, the unit tension of frame #5 is controlled at 190-220N / mm2. For finished steel strips with a thickness of 1.0mm, the unit tension on the #5 frame is controlled at 200-220 N / mm²; for finished steel strips with a thickness of 1.2mm, the unit tension on the #5 frame is controlled at 200-220 N / mm²; for finished steel strips with a thickness of 1.5mm, the unit tension on the #5 frame is controlled at 180-205 N / mm²; for finished steel strips with a thickness of 2.0mm, the unit tension on the #5 frame is controlled at 175-195 N / mm²; for finished steel strips with a thickness of 2.5mm, the unit tension on the #5 frame is controlled at 160-180 N / mm²; for finished steel strips with a thickness of 3.0mm, the unit tension on the #5 frame is controlled at 155-175 N / mm². When rolling ferritic stainless steel with a thickness of less than 1.2mm, the unit tension at the exit of the No. 5 stand should be reduced from 220 N / mm2 to 200 N / mm2 when the thickness or width of the steel plate is excessive or when there is fluctuation in the plate shape. The tension should be restored after stabilization. The maximum width variation is 400mm. Different tension control measures are formulated according to the transition width: A 100mm change in width results in a 25 N / mm² decrease in the unit tension at the outlet of frame #5. A 200mm change in width results in a 30 N / mm² decrease in the unit tension at the outlet of frame #5. A 300mm change in width results in a 35 N / mm² decrease in the unit tension at the outlet of frame #5. A 400mm change in width results in a 40 N / mm² decrease in the unit tension at the outlet of frame #5. The maximum change in thickness specification shall not exceed 0.5mm. When the thickness specification is transitioned, the unit tension at the exit of frame #5 shall be reduced by 40N / mm2. After stopping, the unit tension of the strip shall be reduced by 40N / mm2 during the restart process. S5. Control the rolling process at the weld seam when the weld seam passes through the continuous rolling mill; When the weld passes through the continuous rolling mill, a half-rolling mode is used to reduce the rolling force by 20%. The bending roll value is manually increased by 5-10%. If the deviation exceeds 20mm, stop the machine first and then adjust. S6. Control of work roll replacement; Replace the work roll when the forward slip value is less than or equal to -0.5% for an extended period or when abnormal plate shape occurs at the exit of frame #5.

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