Thin specification stainless steel product operation of rolling control method
Technical field
The invention belongs to the thin size hot-rolled stainless steel product operation of rolling control method of field of metallurgy.
Background technology
At present, China has become the first in the world Chan Gang big country, and hot-strip kind is occupied extremely important status in China's steel and iron industry, and domestic each big steel company is in order to capture as early as possible Strip market, numerous and confused cost huge fund is newly-built or transform thin plate Continuous Rolling Mill, constantly expands variety range and output.Along with the development of hot-strip technology and the aggravation of market competition, develop thin size hot-rolled band steel, realize the development trend that " with hot Dai Leng " becomes current steel market.
Part replaces cold-strip steel, i.e. " with hot Dai Leng "; Use thin size hot-rolled band steel to do cold rolling feeds, can reduce the construction cost of cold rolling and annealing operation, greatly reducing the construction costs, shorten the production cycle; Adopt thin specification to do cold rolling feeds and can reduce cold rolling passage, save energy consumption, thereby reduce production costs; Due to specification price difference, produce thin specification and can make the profit with steel per ton increase, virtually strengthened the competitiveness of enterprise, therefore by analyzing and grasp stainless steel hot-rolling thin plate production and processing technology, become the inevitable demand of market competition.
But in general, China's SPHC production, design level are compared with advanced international standard still certain gap, also need continuous understanding, grasp new technology, new technology that SPHC is produced, promote the quality of hot rolled strip product.
Because the template of thin specification strip is restive, in actual production, there is larger difficulty, cause that operating rate is low, accident rate is high, lumber recovery is low, cause in process control model control accuracy low, Model Self-Learning parameter is unreasonable.
Summary of the invention
The object of the invention is to: a kind of course control method for use that is applicable to thin specification stainless steel product is provided, to guarantee that thin specification stainless steel product can be stablized in the operation of rolling and property production in batches, reduces time of casualty; Guarantee that thin specification quality is controlled, comprise dimensional tolerance, template, and strip surface quality.
The applicant is in to the research of thin specification stainless steel product operation of rolling control method, and transformation mm finishing mill unit, increases to 7 frames by 6 frames, and specification expands to 2.5mm from original 3.0mm, finds under study for action:
1. temperature aspect impact:
In hot rolling thin strip is produced, temperature is the most key on the impact of the operation of rolling.Product specification is thinner, and the temperature drop with steel in the operation of rolling is also larger, can cause head and tail temperature difference like this, thereby impact is with template, dimensional accuracy and the structure property of steel.Simultaneous temperature is lower, and the rolling load of milling train is also larger, also larger to the impact of equipment during threading, is easy to equipment to cause damage.
2. the impact of speed aspect:
Because Thin Strip Steel rolldown speed is very fast, during threading, control adjustment difficulty larger, if adjusted not in time, be easy to occur heap steel accident, can increase threading accident probability like this.Because speed is fast, easily cause whipping while throwing steel, impact band steel Quality of Tail, also can cause damage on breaker roll surface, affects service life and the roll change cycle of roll simultaneously.
3. the impact of mill load:
During due to Thin Strip Steel rolling, mill load is larger, if sharing of load is uneven, directly precision, the quality of the stable and finished product of influence of rolled, also may cause heap steel, and the accidents such as roll breakage, coiling machine driving, cause damage to plant equipment.
4. the impact on strip quality:
The more difficult control of roll coil of strip quality during Thin Strip Steel rolling.During except rolling, easily produce rotten limit, rotten tail, roll brokenly, template harmful effect roll coil of strip quality, Dutch roll when band steel moves on rollgang, foldingly also can cause the problems such as roll coil of strip turriform, loose winding, thereby affect the quality of the roll coil of strip.
Thus, the object of the invention realizes by following technical proposals:
A thin specification stainless steel product operation of rolling control method, comprising:
1) temperature is controlled: heating furnace two adds temperature and is controlled at 1230 ± 20 ℃, this section of minimum time 40min(minute of temperature), soaking zone temperature is controlled at 1270 ± 20 ℃, this section of minimum time 35min of temperature;
2) speed is controlled: roughing the 5th passage mill speed is controlled at 4.5m/s(metre per second (m/s)), more than finish rolling speed is controlled at 9m/s;
3) rolling procedure is controlled:
Roughing rolling procedure is controlled: each passage load is controlled at 27%, 28%, 30%, 31%, 30%, and passage de-scaling to control be 1 time, workpiece thickness is controlled at 28 ± 1mm(millimeter);
Finish rolling rolling procedure is controlled: each frame load is controlled and is, F1:40%, F2:40%, F3:38%, F4:32%, F5:36%, F6:20%, F7:6-9%.F1~F7 represents finishing stand 1~finishing stand 7.
In such scheme, the prior art before relatively transforming, during temperature is controlled, heating furnace two adds temperature and rises to 1230 ℃ by 1190 ℃, soaking zone temperature improves 20-30 degree on the basis of former thermal thermal temperature again, increases the minimum time range restriction of each section of temperature, can prevent that low-temperature steel from coming out of the stove; Speed control centre, roughing the 5th passage mill speed is mentioned to 4.5m/s from 4.2m/s, shorten rolling time about 5 seconds: when speed is 4.2m/s: RDT observed temperature: 1102.48, the intermediate blank transmission time: 65s, intermediate blank temperature computation value: 1031.48, FET observed temperature: 1011.06, intermediate blank transmission time: 48s, intermediate blank temperature computation value: 1003.5.When speed is 4.5m/s: RDT observed temperature: 1109.65, intermediate blank transmission time: 61s, intermediate blank temperature computation value: 1043.30, FET observed temperature: 1013.34, intermediate blank transmission time: 48s, intermediate blank temperature computation value: 1005.75; Finish rolling speed is brought up to more than 9 meters from 8 meters of maximums simultaneously, will be reduced temperature drop 10-20 degree, fast FDT is higher for speed; During rolling procedure is controlled, for roughing rolling procedure, load is optimized: by the sharing of load of front passage, to rear several passages, by 28%, 30%, 32,29%, 28% becomes 27%, 28%, 30%, 31%, 30%; Reduce passage de-scaling: by 2 de-scalings, change 1 de-scaling into; Optimize workpiece thickness: according to rolling, comprehensively feed back, the impact of test 25-32 mm workpiece thickness on rolling, finally selected 28mm is optimised process reference point; Finish rolling rolling schedule optimization: produce thin specification band, each frame reduction ratio obviously improves, arrangement and the traditional handicraft of its rolling schedule are different, for this reason, and depressing distribution and need to be optimized frame, by optimization, depress distribution, the load of afer bay is reduced, prevent that thin specification from rolling rottenly, concrete load range is controlled at 6-9% left and right, little depressing can make production board shape, glacing flatness be easy to control, and reduces heap steel accident.Mm finishing mill unit rear portion frame reduction ratio is excessive, will control and cause larger difficulty to strip profile and flatness.Utilize the roller footpath of F1, F2 frame larger, do not have the problem of nipping, rolled piece, again in high temperature, should apply compared with heavy reduction, to reduce the load of depressing of frame below, completes target Crown control simultaneously.
As selection, described rolling procedure is controlled and is also comprised between each frame that loop tension is controlled at L1:6t(and pause), L2:5t, L3:5t, L4:4.5t, L5:4t, L6:3.5t.L1 represents the loop tension between F1 and F2, and L2 represents the loop tension between F2 and F3, and the rest may be inferred.
In such scheme, loop tension suitably strengthens loop tension between each frame in controlling, and particularly thick Rack Unit tension force, on average increases by 5 unit scalars, thereby make rolling more stable.
As selection, described rolling procedure is controlled and is also comprised afterbody compensation:, when Fi-2 frame is thrown steel, Fi and Fi-1 frame are depressed simultaneously, and i is 3,4,5,6 or 7.
In such scheme, traditional pressure tail is all when band steel afterbody leaves Fi-1 frame, strengthens the drafts of Fi frame, with compensating band steel afterbody, loses and opens thick the jumping producing with temperature drop; Or adopt the mode of " drawing tail ", while being with steel afterbody to leave Fi frame, reduce the speed of Fi+1 frame, Fi+1 and Fi+2 interstand tension are strengthened, with what compensate that Fi and Fi+1 interstand tension disappear, affect one.Make discovery from observation, if only regulate depressing of Fi frame when Fi-1 frame is thrown steel, it is not fine controlling effect, with steel Quality of Tail, still can not get good improvement, therefore adopted two methods of simultaneously pressing tail, namely, when Fi-2 frame is thrown steel, Fi and Fi-1 frame are depressed simultaneously.
As selection, described rolling procedure is controlled and is also comprised rolling scaduled control: carry out the plan from thick to thin non-jump, transition thickness 0.2 ± 0.15mm.Further, through 1-3 piece 3.0mm(thickness of slab) Direct Rolling 2.5-2.85mm specification slab after slab rolling.Further, in 28 slab rollings, rolling scaduled control is followed successively by three of 3.0mm slab rollings, two of 2.85mm slab rollings, ten of 2.5mm slab rollings, six of 2.85mm slab rollings, six of 3.0mm slab rollings, one of 4.0mm slab rolling.
In such scheme, rolling scaduled layout can make on-the-spot rolling stable, guarantees rolling smoothly when the thin specification of rolling; Rolling scaduled layout is proper, can also improve band steel head thickness hit rate.The thin specification of Direct Rolling after 1-3 piece 3.0, rolling is stable, and thickness is easy to control.
As selection, adopt hot-rolling lubricating technology, be specially: the F2-F5 frame that comes into operation, oil mass is 50 milligrams, delays oil spout in 1 second, throws first 1 second pass oil of steel when sequential is threading.
In such scheme, for the thin specification of the rolling torrid zone, hot-rolling lubricating technology has important function, it can reduce roll-force, reduces roll loss, improve surface quality, the F2-F5 that comes into operation, oil mass is 50 milligrams, delays oil spout in 1 second, throws steel and within first 1 second, close oil when sequential is threading, roll-force can lower 15% left and right, is convenient to the thin specification of rolling 2.0 left and right.
The main scheme of aforementioned the present invention and each further selection scheme thereof can independent assortment to form a plurality of schemes, be that the present invention can adopt and claimed scheme.As the present invention, each selects to get final product and main scheme and other selection any combination, and those skilled in the art can understand there is multiple combination according to prior art and common practise after understanding the present invention program, at this, do not do exhaustive.
Beneficial effect of the present invention: process milling method of the present invention, improved rolling stable state, effectively guaranteed the structure property of product, reduced steel scrap rate, lumber recovery promotes, reduced roller consumption simultaneously, thereby reduced rolling cost, improved the quality of stainless steel product, surface quality, dimensional accuracy, template, machinability are good, can meet user's instructions for use completely, increase the market competitiveness of stainless steel product.
Accompanying drawing explanation
Fig. 1 is stainless steel production technological process of the present invention;
Finish rolling F7 outlet temperature under the frame friction speed of mm finishing mill unit end when Fig. 2 is rolling J4-X 2.5*1235 of the present invention;
Fig. 3 is rolling scaduled schematic diagram during finish rolling rolling procedure of the present invention is controlled;
In figure, 1 is walking beam furnace, and 2 for dephosphorization case 1,3 is E1/R1 roughing mill, and 4 is Coil Box, and 5 is crop flying shear, and 6 for dephosphorization case 2,7 is mm finishing mill unit, and 8 is that laminar flow is cooling, and 9 is downcoiler.
The specific embodiment
As Figure 1-3, following non-limiting examples is used for illustrating the present invention.
1, temperature optimization:
The thin specification temperature impact of rolling comprises that furnace temp impact and band steel affect at mill temperature.Some knowhows show, each section of furnace temperature of raising heating furnace and the slab time inside furnace of appropriateness when the thin specification of rolling are controlled tapping (rolling) rhythm to guarantee the tapping temperature of slab simultaneously, are conducive to reduce rolling load, improve rolling stability.Find under study for action:
When lower the or temperature of furnace temp is unstable:
1, during the thin specification J4-2 2.5*1235 of rolling, two add temperature is controlled at 1172-1192 ℃, and soaking zone temperature is controlled at 1221-1239 ℃.As can be seen from the table, under this heating cycle, frame load is heavier.
Under tapping temperature same case, heating furnace two adds temperature and is reduced to gradually 1165 ℃ by 1193 ℃, if constantly reduce heating furnace two in rolling procedure, adds the load that furnace temperature will certainly have influence on milling train.
Tapping (rolling) rhythm is on finish rolling inlet temperature and roll-force impact.The statistics of doing with rolling 304 2.8*1240 roll-force trend and research (precondition: thick, finish rolling rolling procedure is constant), totally 19 of coil of strips were tapped 19 in 145 minutes, on average with 7.6 minutes, going out a steel is rolled, its each frame roll-force changes as follows: F1 increases more obvious gradually, and F2 has increase tendency, and F3 increases gradually, F4 has increase tendency, but less, F5 increases gradually, and increase obviously, F6 roll-force changes little, and F7 roll-force increases gradually.
Further, heating furnace two is added to temperature optimization or each section of temperature stabilization:
1) heating furnace two adds temperature and rises to 1207 ℃ by 1190 ℃, soaking zone 1235-1240, after rise to again 1256, and keep its each section of furnace temperature always, when rolling J4-X 2.5*1235: F1 mill rolling force is stable and have the trend of diminishing, and F2 mill rolling force is stable and have the trend of diminishing, and F3 mill rolling force is stable, F4 mill rolling force is stable and have the trend of diminishing, and F5-F7 mill rolling force is stable.
Thus, temperature is controlled and is defined as the most at last: heating furnace two adds temperature and is controlled at 1230 ± 20 ℃, this section of minimum time 40min of temperature, and soaking zone temperature is controlled at 1270 ± 20 ℃, this section of minimum time 35min of temperature.
2, speed-optimization:
improve roughing the 5th pass speed:
When speed is 4.2m/s:
RDT observed temperature: 1102.48, intermediate blank transmission time: 65s, intermediate blank temperature computation value: 1031.48, FET observed temperature: 1011.06, intermediate blank transmission time: 48s, intermediate blank temperature computation value: 1003.5.
When speed is 4.5m/s:
RDT observed temperature: 1109.65, intermediate blank transmission time: 61s, intermediate blank temperature computation value: 1043.30, FET observed temperature: 1013.34, intermediate blank transmission time: 48s, intermediate blank temperature computation value: 1005.75.
improve finish rolling speed:
As shown in Figure 2, while improving front ultra-thin gauge rolling, F7 speed is generally all arranged on 7.5~8.0m/s, and when the thin specification of rolling, mill speed is too low.
Thus, final speed is controlled and is defined as: roughing the 5th passage mill speed is controlled at 4.5m/s, more than finish rolling speed is controlled at 9m/s.
3, rolling schedule optimization:
roughing rolling schedule optimization:
Roughing load is optimized.Finally be defined as, by the sharing of load of front passage, to rear several passages, by 28%, 30%, 32,29%, 28% becomes 27%, 28%, 30%, 31%, 30%;
Reduce passage de-scaling, when the thin specification of rolling, reduce the de-scaling of roughing passage.Passage de-scaling is made as 1 time by 2 secondary controls.
The optimization of workpiece thickness, arranges the workpiece thickness of different size different-thickness.Result of the test is the most suitable for workpiece thickness when the thin specification of rolling is arranged on 28 ± 1mm, and when being greater than 28mm, finish rolling load is influenced, and while being less than 26mm, roughing road primary current increases, and there will be motor overload situation.
finish rolling rolling schedule optimization:
Optimize tension force and set, according to kink, adjust situation, strengthen thin specification unit tension, especially rear several unit tensions, guarantee that frame rolling situation is very stable, reduce the strip shake causing because rolling thin specification between frame.Finally be defined as, between each frame, loop tension is controlled at L1:6t, L2:5t, L3:5t, L4:4.5t, L5:4t, L6:3.5t.
Produce thin specification band, each frame reduction ratio obviously improves, and arrangement and the traditional handicraft of its rolling schedule are different, for this reason, to the depressing distribution and need to be optimized of frame, by optimization, depress distribution, can make production board shape, glacing flatness be easy to control, reduce heap steel accident.Mm finishing mill unit rear portion frame reduction ratio is excessive, will control and cause larger difficulty to strip profile and flatness.Utilize the roller footpath of F1, F2 frame larger, do not have the problem of nipping, rolled piece, again in high temperature, should apply compared with heavy reduction, to reduce the load of depressing of frame below, completes target Crown control simultaneously.Finally be defined as, each frame load is controlled and is, F1:40%, F2:40%, F3:38%, F4:32%, F5:36%, F6:20%, F7:6-9%.
Afterbody compensate function all has input at present in a lot of AGC systems, mainly contains and presses tail and draw two kinds of modes of tail.Traditional pressure tail is all when band steel afterbody leaves Fi-1 frame, strengthens the drafts of Fi frame, with compensating band steel afterbody, loses and opens thick the jumping producing with temperature drop; Or adopt the mode of " drawing tail ", while being with steel afterbody to leave Fi frame, reduce the speed of Fi+1 frame, Fi+1 and Fi+2 interstand tension are strengthened, with what compensate that Fi and Fi+1 interstand tension disappear, affect one.Make discovery from observation, if only regulate depressing of Fi frame when Fi-1 frame is thrown steel, it is not fine controlling effect, with steel Quality of Tail, still can not get good improvement, has therefore adopted two methods of simultaneously pressing tail, namely at Fi-2.When frame is thrown steel, Fi and Fi-1 frame are depressed simultaneously.
Loop tension is optimized, and suitably strengthens loop tension between each frame, makes rolling more stable: in hot continuous rolling, tension force is set with a relatively-stationary a reference value, and Minimal Tension carries out around a reference value while regulating.But existing facts have proved, less than normal when the thin specification of rolling, rear portion frame rolling is unstable, and between frame there is very large shake in strip, and thin plate heap steel rate increases.Suitably heightening after a reference value, rear portion frame rolling is stable, and between frame, strip shake obviously reduces, and thin plate heap steel rate reduces greatly.
Thin specification loop tension Optimal Example:
Rolling scaduled layout optimization, is more renewing after roller, is all 28 blocks of slabs, rolling scaduled layout contrast in the identical situation of rolling specs:
The thin specification of Direct Rolling after 4.0mm slab rolling, because roller heat convex degree learning is unstable, may cause the unstable or afterbody of head threading to be fried rotten.
After 4.0mm slab rolling excessively after 1-2 piece 3.0mm slab rolling, the thinner specification of rolling, template easily regulates, and rolling is stable, but 4.0 thickness are wayward.
The thin specification of Direct Rolling after 1-3 piece 3.0mm slab rolling, rolling is stable, and thickness is easy to control, but the requirement of operating technology level is high.
As shown in Figure 3, carry out the plan from thick to thin non-jump, transition thickness 0.2 ± 0.15mm, Direct Rolling 2.5-2.85mm specification slab after 1-3 piece 3.0mm slab rolling.Specifically be followed successively by three of 3.0mm slab rollings, two of 2.85mm slab rollings, ten of 2.5mm slab rollings, six of 2.85mm slab rollings, six of 3.0mm slab rollings, one of 4.0mm slab rolling.
In addition, few at excessive sheet material, when specification is more single, operating technology level requires high, has rolling unsteady phenomena (afterbody rolls rotten).
Adopt lubrication and rolling technology, for the thin specification of the rolling torrid zone, hot-rolling lubricating technology has important function, and it can reduce roll-force, reduces roll loss, improve surface quality, and this is special distinct issues in the thin specification of the rolling torrid zone just.
Finally be defined as: the F2-F5 frame that comes into operation, oil mass is 50 milligrams, delays oil spout in 1 second, throws first 1 second pass oil of steel when sequential is threading.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.