JP2576916B2 - Thick plate rolling method in pair cloth rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pair cross rolling mill in which upper and lower rolls are crossed and rolled, and realizes high-efficiency rolling in which the number of passes is minimized and optimizes the rolling shape. The present invention relates to a method of rolling a thick plate for achieving a proper pass schedule.

[0002]

2. Description of the Related Art As a method for determining a pass schedule in a conventional rolling mill (reversing rolling mill), for example, Japanese Patent Laid-Open No.
As shown in -259605, for the purpose of flattening the rolling shape, the change of the sheet crown (= the thickness of the center portion or the roll interval in the sheet width direction-the thickness of the edge portion or the roll interval) for each pass is controlled. Therefore, there is a method of determining the rolling reduction schedule under the condition that the rolling load is less than the maximum allowable capacity of the equipment. In this case, a method is used in which the rolling load is calculated from a thicker plate to a thinner plate, the calculation is terminated when the plate thickness is exceeded, and the number of passes is once fixed and then distributed.

Further, in order to perform rolling at high efficiency, there is a method in which rolling is performed at full load in an upstream pass having a small influence on the shape, and a change in the sheet crown is sensitive to the shape, and the load is suppressed only in a downstream pass to determine a pass schedule. It has been proposed in JP-B-63-123. On the other hand, in the case of a pair cross rolling mill in a hot strip mill, a method has been proposed in which a draft schedule is determined in advance and then a roll crossing angle schedule is determined so as to satisfy the shape (The Iron and Steel Institute of Japan, No. 120). Lecture meeting, CAMP-ISIJ
vol 3, 1990, p. 1383).

[0004]

However, in the above prior art, in order to flatten the shape of the rolled material, it is necessary to suppress the change of the sheet crown for each pass within a certain range (that is, the center of the rolled material). It is necessary to suppress the part from bulging into a barrel shape)
Therefore, there is a problem that the rolling load, which is a controlling element of the mechanical crown, is restricted, and the rolling must be performed with a load much smaller than the allowable capacity of the equipment. As a result, the number of passes is large and the rolling efficiency is reduced. In addition, in order to perform rolling at high efficiency, it is conceivable to determine the pass schedule by rolling at full load in the upstream pass where the shape influence is small and suppressing the load only in the downstream pass where the change of the sheet crown is sensitive to the shape. However, the rolling reduction in the number of downstream passes is not eliminated, and the rolling load change in the lower load pass giving priority to the full load pass and shape is large. Thus, a rolled material having a good shape was not always obtained. On the other hand, in the case of a pair cross rolling mill in a hot strip mill, the number of passes is basically unchanged from the number of stands. Therefore, after a draft schedule is determined in advance, a schedule of the roll crossing angle is determined so as to satisfy the shape. However, it was not applied as a method of determining a pass schedule of thick plate rolling in which the number of passes is variable. The object of the present invention has been made in view of the above-mentioned prior art,
When rolling a sheet material using a pair cross rolling mill, the thickness of a pair cross rolling mill that maximizes the original capacity of the rolling equipment throughout all passes, realizes high-efficiency rolling that minimizes the number of passes, and optimizes the rolling shape An object of the present invention is to provide a sheet rolling method.

[0005]

In order to achieve the above object, the present invention provides an upper roll and a lower roll each comprising a set of a backup roll and a work roll in a plane parallel to a material to be rolled. In a pair crossing rolling mill relatively intersected with each other, the mechanical crown allowable range is calculated from the shape in each pass, and based on the calculated value, the rolling amount of the shortest number of passes satisfying the shape and the schedule of the intersection angle are calculated by stacking. Thus, the maximum allowable rolling load is determined.

[0006]

According to the above-mentioned means, the shape of the rolled material, the crown and the rolling amount (load) schedule are simultaneously determined for each pass in accordance with the shape control ability for all the passes, and the stacking calculation is performed using the optimum value for each pass. And the schedule of the rolling amount and the intersection angle of the shortest number of passes satisfying the shape are calculated. As a result, the schedule that satisfies the shape in all the passes and that can be rolled is determined by the maximum value of the rolling equipment capacity.
In addition, since the number of passes is automatically adjusted according to the shape control ability, the ability to vary the number of passes in the reversible rolling mill is sufficiently exhibited.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing an outline of a process for realizing a plate rolling method according to the present invention, and FIGS.
4 is a flowchart showing details of the processing in FIG.
FIG. 3 is a block diagram illustrating a configuration example of a control system for implementing the processing of FIG. First, the configuration of FIG. 4 will be described. Here, details of the process computer 1 using the business computer 2 as a host computer are shown.
The process computer 1, with the support of the business computer 2, calculates a schedule such as a sheet thickness and a cross angle for each pass in advance before starting rolling, and determines a processing content of the entire finishing rolling pass beforehand. 1
1. The roll profile estimation calculation unit 12 that performs calculation for estimating the roll profile, and the schedule obtained by the finish pass schedule calculation unit 11 is set in the finishing plant controller 4 described later while actually rolling the plate for each pass. A finish adaptive control calculation unit 13 that transmits a value and performs a learning calculation for feed-forwarding the actual information between the passes to the next pass in real time to perform a correction calculation for setting a more accurate next pass, a rolling process. The error of the predicted value is calculated based on the actual measured value of the thickness of the gamma ray thickness gauge 2 for detecting the thickness of the workpiece 5 to be processed later and the actual calculated value by the finish adaptive control calculation unit 13, and the prediction calculation for the next pass and thereafter is performed. Finish learning meter that plays a role in improving control accuracy by modifying the path schedule and reflecting it in the path schedule calculation and the adaptive control calculation. And a respective section 14.
The finish adaptive control calculation unit 13 receives a set value of the next pass (roll gap set value, roll cross angle, etc.) during rolling, and performs finish for actually driving the finish rolling mill 3 based on the value. A plant controller (finish DDC) 4 is connected, and each of a roll-down value set value, a cross angle set value, a bender pressure set value, a target value crown set value, and a crown control coefficient provided from the finish adaptive control calculation unit 13 The rolling control of the pair cross rolling mill 3 is performed according to the following.

FIG. 5 and FIG. 6 are a plan view and a side view showing the details of the finishing mill 3. As shown in FIG. 5, the work material 5 can be sandwiched from above and
a, the lower work roll 6b is arranged crosswise.
Each roll is disposed at an angle θ in the horizontal direction on a line perpendicular to the traveling direction of the workpiece 5. The upper work roll 6a is provided with an upper backup roll 7a parallel to the upper side thereof, and a lower backup roll 7b is provided below the lower work roll 6b in parallel with the lower work roll 6b. In the figure, b is the width of the rolled material, D _w is the work roll diameter, roll cross angle of θ is 1/2, the S _c roll distance of the plate center portion, roll spacing at the S _e is the plate edge portion Are respectively shown. 5 and As is apparent from FIG. 6, to roll distance S _c of the plate center portion, the roll gap S _e on the plate edge portion is wider roll cross angle becomes large, the crown ratio smaller this roll cross angle becomes larger Becomes larger. However, as described above, in order to flatten the shape of the material to be rolled, it is necessary to suppress the change of the sheet crown for each pass within a certain range, and it is not possible to take a large roll crossing angle at one time. Further, as shown in FIG. 4, a load cell 8 is provided for detecting the rolling load of the upper work roll 6a, and a thermometer 9 is provided for detecting the surface temperature of the workpiece 5 after rolling. Have been.

Next, the operation of the control system shown in FIG. 4 will be described with reference to the flowcharts of FIGS. Note that S in the figure means a step. In the pass schedule determining method according to the present invention, first, the target final exit sheet thickness and sheet crown amount are set (S2).
1). Next, after simply assuming the finishing temperature and finishing direction of the final pass (S22, S23) , the plate of the material to be rolled sent from the rough rolling is calculated by the following calculation.
Until it exceeds the thickness dimension (transfer thickness = plate thickness at the start of finish rolling)
To calculate the accumulation from the flow path to the upstream path
The roll reduction and roll crossing angle are determined simultaneously for each pass
I will do it. For example, the material to be rolled
The thickness (transfer thickness = finish rolling start thickness) is 50 mm.
Final pass exit side plate thickness is 10mm, rolling reduction of each pass is downstream pass
2mm, 2.5mm, 3m toward more upstream path
m, ..., the entry side thickness of each pass is 12m
Set as m, 14.5mm, 17.5mm, ...
And finally, it is repeated in the path where the entry side plate thickness exceeds 50mm.
Return calculation ends. That is, first, it is determined whether or not this pass is a descaling execution pass (S24), and then the temperature on the entry side (biting side) of this pass and the expected rolling speed are assumed (S25, 26). ). Here, the upper and lower limit ranges and target values (denoted as λ _max , λ _min , and λ _aim ) of the permissible steepness of this pass are given from the plate width and the exit side plate thickness of the rolled material. This λ _aim is basically 0, and λ _max , λ _min
The value is a parameter indicating the allowable range of the shape according to each rolled material size, and is empirically determined according to the operation situation. Using this λ value, the allowable elongation-strain difference and the target elongation-strain difference are calculated from Δε = (π / 2) ² · λ ² (1), and further, C _in / h _in = C _out / h _out −Δε / ξ + α (2): Δε max (maximum value), min (minimum value),
Aim (target value) is given, and the allowable range of the sheet crown ratio on the entry side and the target value are calculated (S27). However, C _in: entry side crown h _in: thickness at entrance side C _out: delivery side crown h _out: delivery side thickness [Delta] [epsilon]: elongation strain difference xi]: values shapes representing the sensitivity (change in shape coefficient) alpha: shape change correction it is engaged number. Here, max, min, a of (C _in / h _in )
From im, the allowable range and the target value of the mechanical crown MCK restricted by the shape of this pass by the following equation are calculated (S28). MCK = 1 / (1−η) · {C _out −η · h _out · (C _in / h _in )} (3) (where η is the crown genetic coefficient)

On the other hand, from the rolling load and the allowable capacity of the equipment,
The mechanical crown MCh has a rolling load P,
Loading load F, roll crossing angle, roll profile
Can be estimated by the following equation. MCh = c1 · P + c2 · F + E + c3 (4) where P: rolling load F: roll bending load E: mechanical crown formed by roll crossing angle
Amount c1: Mechanical crown influence coefficient by rolling load c2: Mechanical crown influence by bending load
Coefficient c3: Mechanica formed by local profile
Le crown amount. When there is no roll bending control device
The second term of the equation (4) is omitted, and the roll cloth device
If there is no, if the third term in equation (4) is omitted,
To calculate the mechanical crown MCh from the load
it can. In equation (4), the maximum rolling load P_max, Minimum exchange
Bevel angle 2θ_min, MCh becomes maximum, and conversely, minimum pressure
Rolling load P_min, The maximum cross angle 2θ_maxWhen MCh is minimum
To determine mechanical crown tolerance from equipment load
Yes (S29). (3) Mechanica from shape
And the equipment load from equation (4).
The range that satisfies both the canal crown tolerance range is
Determined as true mechanical crown tolerance on pass
Is determined. In addition, MCK within this range_aimExists
The true mechanical crown target value MC
_aimIs determined (S30).MCK _aim ： Target mechanical crown MCK _max : Mechanical club from the shape according to equation (3)
Allowable maximum value MCK _min : Mechanical club from the shape according to equation (3)
Minimum allowable value MCh _max : Mechanical from equipment load by equation (4)
Crown allowable maximum value MCh _min : Mechanical from equipment load by equation (4)
Crown Minimum MC _max : Constraint from shape by equation (3) and (4)
From the equipment load by the formula Maximum allowable mechanical crown that satisfies both constraints MC _min : Constraint from shape by equation (3) and (4)
From the equipment load by the formula Mechanical that satisfies both constraints
Crown Minimum And At this time, MC _max And MC _min Is MC _max = MIN (MCK _max , MCh _max ) MC _min = MAX (MCK _min , MCh _min ) Is determined by In addition, check consistency as follows:
Do a check. MCK _max <MCh _min Then MC _max = MC _min = M
Ch _min And MCK _min > MCh _max Then MC _max = MC _min = M
Ch _max And After this, MC _max And MC _min M to be within the range
CK _aim To correct. MC _min ≤MCK _aim ≤MC _max Then MCK _aim Is strange
Do not change. MC _max <MCK _aim Then MCK _aim = MC _max MCK _aim <MC _min Then MCK _aim = MC _min Also, it is not possible to modify the value of the previous path
Not generally.

Then, MC_aimTo achieve
The rolling reduction r, the roll cross angle 2θ, and the bendin
The optimal combination of the load F is determined at the same time (S3
1).This determination method is, for example, using the following method
You. The allowable range of the rolling reduction (rmax,
rmin). Target mechanical crown (MCK _aim Before achieving
Assuming that the bending load F is a constant value, Roll cross angle θ1 at rmax (maximum load) roll cross angle θ2 when rmin (minimum load) Were determined using the equations described below. Target mechanical crown (MCK _aim Before achieving
Assuming that the bending load F is a constant value, θ _max (Roll crossing angle maximum) Reduction ratio r1 θ _min (Roll crossing angle minimum) reduction ratio r2 Were determined using the equations described below. True roll crossing angle tolerance (θR _min , ΘR _max )as well as
Allowable rolling reduction (rR _min , RR _max ). θR _min = MAX (θ _min , Θ2) θR _max = MIN (θ _max , Θ1) rR _min = MAX (rmin, r2) rR _max = MIN (rmax, r1) True roll crossing angle tolerance (θR _min , ΘR _max )And
True reduction rate tolerance (rR _min , RR _max )
Described below using linear programming to maximize the rate
Determine the rolling reduction and roll crossing angle by the formula
Bending force is constant). The first target thickness value at this stage
Each value for (here, 10 mm) is determined. You
That is, if P = fp (r) E = fe (2θ), then from equation (4), MC_aim= C1 · fp (r) + c2 · F + fe (2θ) + c3, so that r = fr (MC_aim, 2θ, F)... (5)_aimUnder constant conditions, the rolling reduction r is 2
The search can be determined based on θ and the bending load F. (5)
In the formula, generally, high efficiency rolling is
2θ, bending load so that the rolling reduction r is maximized.
Determine the weight F. In addition, other operations using the evaluation function etc.
Reflect the business conditions and determine the optimal combination by linear programming, etc.
It is also possible to ask. I decided the rolling reduction r
Calculate the thickness of the entry side and include the temperature change in the roll tool.
To calculate the amount of temperature drop on the exit side of this pass (S32),
Recalculate the plate temperature at the time of biting. Then use that temperature
To calculate more accurate rolling load and rolling torque (S
33, 34), after checking the load (S35), the next upstream
Repeated calculation of temperature, load and crown in pass
(S36, 37, 38, 40). Total for each pass above
Calculation from the downstream path to the upstream path
As a result, the pass schedule is determined sequentially, and finally the pass
Rolling in a pass where the thickness on the entry side exceeds the planned thickness at the start of rolling
Return calculation ends. When creating this pass schedule
If the planned thickness at the start of rolling cannot be changed,
Perform load distribution correction calculation as necessary, and
After completing the calculations, complete the pass schedule
To determineIn addition, regarding the calculation method described in FIG.
Thermometer indicated by S22, S25, S32, S36, S40
For the calculation, for example, “Sheet Rolling Theory and Practice” (Nippon Steel
Steel Association of Rolling Theory Section), pages 146-149.
Rolling load calculation and S33 shown in S33
The calculation of the rolling torque indicated by 34 is, for example, described in
Theory and Practice "(edited by The Iron and Steel Institute of Japan)
The calculation method described on pages 6 to 38 is used. Other
about

[0009]

The method described in the column is followed.

Next, an embodiment in which the pass schedule of the rolled material is determined according to the above-described procedure of the present invention will be described. (Example 1) The pass schedule of the rolled material was calculated under the following preconditions. Final target thickness: 6.0mm Final pass exit side plate crown amount: 0.02mm Plate width: 3500mm Finishing temperature of final pass: 750 ° C Finishing in the rear direction Descaling execution pass: First pass from initial pass, third pass, maximum cross angle : 0.585 ° This precondition is based on the actual business computer 2
From rolling material information, or provided as information patterned according to operating conditions. Next, the rolling schedule and the roll crossing angle schedule were simultaneously determined for each pass sequentially from the downstream pass toward the upstream pass by the following calculations. Here, the calculation process of the last one pass (calculation start pass) is shown by a numerical example. [Assumption of Inlet-side (biting-side) Temperature] Assume that the temperature drop amount is 30 ° C. and the inlet-side biting assumed temperature is 780 ° C. [Assumption of Scheduled Rolling Speed] From the sheet width of the rolled material and the exit side sheet thickness, the standard mill speed is set to 100 rpm. [Upper and lower limit range and target value of allowable steepness] λ _max = 0.4%
λ _min = −0.4% λ _aim = 0. (This is a parameter that indicates the allowable range of the shape according to each rolled material size, and is determined by an experienced person according to the operating condition using a table value.) [Calculate the allowable elongation-strain difference and the target elongation-strain difference] (Π / 2) ² · λ ² Δε _max = 0.004% Δε _min = −0.004% Δε _aim = 0 [Calculate the allowable range and target value of the entrance-side sheet crown ratio] According to the equation (2), C _in / h _in = C _out / h _out -Δε /
ξ + α α = 0.15 ξ = 0.61 C _out / h _out = 0.03% (C _in / h _in ) max = 0.49% min = 0.48% aim = 0.48% [Constrained by shape Calculate the allowable range and target value of the mechanical crown to be used] From equation (3), MCK = 1 / (1−η) · ｛C _out −η
/ H _out · (C _in / h _in )｝ η = 0.702 MCKmax = 0.00 mm min = 0.00 mm aim = 0.00 mm [Permissible range of mechanical crown from rolling load and equipment permissible capacity] P _max = 6500 ton P _min = 2200 ton θ _max = 0.585 ° θ _min = 0.000 ° F = 130 ton From equation (4), MCh = c1 · P + c2 · F + E + c3 MCh _max = 0.72 mm MC _min = 0.66 mm The fixed value was set on the assumption that the roll bending load was not preset. [Determination of true mechanical crown allowable range and aim value MC _aim ] MC _max = 0.00 mm MC _min = 0.00 mm MC _aim = 0.00 mm [Search and determination of rolling reduction r, roll cross angle 2θ, bending load F] In equation (5), when searching for the maximum rolling reduction in order to direct high-efficiency rolling, under the condition of fixing F, θ = θ _{max =}
= 0.585 °, and r = 0.597 (= r
seek) is obtained. [Calculation of the thickness of the inlet side] From h _in = h _OUt / (1-r), h _in = 7.14 mm [Estimation of the temperature drop on the exit side of the pass] Temperature drop = 15 ° C. Sheet temperature during biting = 765 ° C [Calculation of rolling load and rolling torque] P = 5420 ton toque = 198 ton. m, all within the facility capacity range. [Estimation Calculation of Temperature Drop on Pass Inlet] Temperature drop = 21 ° C Plate temperature at exit of previous pass = 786 ° C When temperature is not less than 786 ° C, calculation of temperature, load and crown for one pass is completed. By calculating the above calculation for each pass from the downstream pass to the upstream pass, the pass schedule is determined in sequence, and finally the pass entry side thickness is repeatedly calculated for the pass that exceeds the planned thickness at the start of rolling. To end. In this embodiment, the pass schedule for all passes was calculated with the scheduled thickness of the start of rolling as 50 mm. 7, 8 and 9 show the results in comparison with the conventional method. In each case,
The shape adjustment ability by the roll cross function is the same,
In the conventional pass schedule, the crossing and rolling loads do not reach the maximum capacity of the equipment, and the number of passes increases. As a result, in the present invention, the schedule calculation is performed by searching the allowable maximum. Therefore, the shortest number of passes can be achieved while maintaining the shape. In addition, compared to the conventional method, the drawback that the rolling load of the downstream path of the shape adjustment and the rolling path of the full load in the conventional method become discontinuous by the calculation of the entire path is eliminated, and a smooth rolling load trend is obtained. Can be Conventionally, for shape adjustment, it was necessary to secure several paths on the end side of all the paths as shape adjustment paths, but this is not required in the present invention.

(Example 2) A pass schedule of a rolled material was calculated based on the following preconditions. Final target thickness: 20.0mm Final pass exit side plate crown amount: 0.00mm Plate width: 3500mm Finishing temperature of final pass: 850 ° C (finish in back direction) Descaling execution pass: First pass from initial pass Maximum cross angle: 0 0.000 ° (without cross function) Maximum rolling load: 4000 tons Planned thickness at the start of rolling: 85 mm FIG. 10 shows the result of calculating the pass schedule for all passes in the present invention.

(Embodiment 3) The pass schedule of the rolled material was calculated based on the following preconditions. Final target thickness: 45.0mm Final pass exit side sheet crown: -0.20mm Plate width: 1500mm Finishing temperature of the final pass: 850 ° C (finish in the rear direction) Descaling execution pass: 1, 3, 5th pass from the initial pass Maximum cross angle: 0.900 ° C. Maximum rolling load: 6000 ton Maximum torque: 420 ton Planned thickness at the start of rolling: 157 mm FIG. 11 shows the result of calculating the pass schedule for all passes in the present invention.

[0015]

As is clear from the above, according to the present invention, the upper roll and the lower roll, each of which is a set of a backup roll and a work roll, are relatively moved in a plane parallel to the material to be rolled. In the crossed pair cross rolling mill, the mechanical crown allowable range is calculated from the shape in each pass, and the rolling amount of the shortest number of passes and the schedule of the crossing angle satisfying the shape are calculated based on the calculated value and the maximum allowable rolling is calculated by stacking. Since the load is determined, the schedule that satisfies the shape in all passes and that can be rolled is determined by the maximum value of the rolling equipment capacity. Also,
Since the number of passes is automatically adjusted in accordance with the shape control ability, the ability to vary the number of passes in the reversible rolling mill is sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the entire process of realizing a thick plate rolling method according to the present invention.

FIG. 2 is a flowchart showing details of the processing in FIG. 1;

FIG. 3 is a flowchart showing details of processing subsequent to FIG. 2;

FIG. 4 is a block diagram showing a configuration example of a control system for realizing the processing of FIG. 1;

FIG. 5 is a plan view showing details of a finishing mill.

FIG. 6 is a side view showing details of a finishing mill.

FIG. 7 is a comparison diagram showing pass schedule calculation results for all passes of the present invention in which the expected thickness at the start of rolling is 50 mm, in comparison with the conventional method.

FIG. 8 is a graph of the number of passes versus rolling load, showing the results of FIG. 7 in a graph.

FIG. 9 is a graph showing the result of FIG. 7 in a graph showing the relationship between the thickness of the delivery side and the rolling load.

FIG. 10 is a comparison diagram in which path schedules for all paths corresponding to the second embodiment of the present invention are calculated.

FIG. 11 is a comparison diagram showing calculated path schedules for all paths corresponding to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Process computer 2 Business computer 3 Finishing mill 4 Finishing plant controller 5 Work material 6a Upper work roll 6b Lower work roll 7a Upper backup roll 7b Lower backup roll 8 Load cell 9 Thermometer 11 Finish pass schedule calculation unit 12 Roll profile estimation calculation Unit 13 Finish adaptive control calculation unit 14 Finish learning calculation unit

Claims (1)

(57) [Claims] 1. A pair cross rolling mill in which an upper roll and a lower roll, each comprising a set of backup rolls and work rolls, relatively intersect in a plane parallel to a material to be rolled, and a shape in each pass. The mechanical crown allowable range is calculated from the calculated value, and the rolling amount and the crossing angle schedule of the shortest number of passes satisfying the shape are determined based on the calculated value so as to be the allowable maximum rolling load by the stacking calculation. Plate rolling method in a pair cloth rolling mill.