JPH04270005A - Method for rolling thick plate on pair cross rolling mill - Google Patents

Abstract

PURPOSE:To realize the high efficient rolling so as to make the pass number minimum and to make the rolling shape most switable by obtaining the shape, the crown, the draft schedule of the rolled stock for every pass, calculating integrally with the most switable value for every pass, and utilizing the essential capacity of the rolling equipment to the max. over every pass. CONSTITUTION:On the pair cross rolling mill that the upper side roll and the lower side roll which are composed respectively with the back up roll and the working roll are crossed relatively in X shape like against the parallel plane to the rolled stock, the mechanical crown allowable range is calculated with the shape at each pass, based on this calculated result, the rolling reduction of min. pass number and the schedule of crossing angle satisfying the shape are decided so as to be made to the allowable max. rolling load with the integral calculation.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a pair-cross rolling mill that performs rolling by crossing upper and lower rolls in pairs, which realizes high-efficiency rolling with the minimum number of passes and optimizes the rolled shape. The present invention relates to a thick plate rolling method for achieving a suitable pass schedule.

0002

[Prior Art] As a method for determining a pass schedule in a conventional rolling mill (reversible rolling mill), for example, Japanese Patent Laid-Open No. 62
- As shown in 259605, the change in plate crown (=thickness at the center or roll spacing in the width direction of the plate - thickness at the edge or roll spacing) is controlled for each pass for the purpose of flattening the rolled shape. Therefore, there is a method of determining the rolling schedule under conditions that restrict the rolling load to less than the maximum allowable capacity of the equipment. In this case, a method is used in which the rolling load is calculated from the thicker plate to the thinner plate, the calculation is terminated when the plate thickness is exceeded, and the number of passes is fixed once and distributed.

[0003] In addition, in order to achieve high efficiency rolling, there is a method in which the pass schedule is determined by rolling at full load in the upstream pass, where the influence of shape is small, and by suppressing the load only in the downstream pass, where changes in the plate crown are sensitive to the shape. It was proposed in the Special Publication Act 1986-123. 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 the draft schedule is determined in advance and then the schedule of the roll crossing angle is determined so as to satisfy the shape (Iron and Steel Institute of Japan, 120th Lecture conference, CAMP-ISIJ
vol 3, 1990, p. 1383).

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, in order to flatten the shape of the rolled material, it is necessary to suppress the change in the plate crown for each pass within a certain range (i.e., the center (need to prevent the part from expanding into a barrel shape)
Therefore, the rolling load, which is a controlling element of mechanical crowns, is restricted, and rolling must be performed with a load far lower than the equipment's allowable capacity, resulting in a problem of a large number of passes and a decrease in rolling efficiency. In addition, in order to achieve high efficiency rolling, it may be possible to roll at full load in the upstream pass where the influence of shape is small, and to determine the pass schedule by reducing the load only in the downstream pass, where changes in plate crown are sensitive to shape. However, the light reduction corresponding to the number of downstream passes is not resolved, and furthermore, the rolling load change in the full load pass and the lower pass that prioritizes the shape is large. Because of this, it was not always possible to obtain a rolled material with a good shape. 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 depending on the number of stands, so after determining the draft schedule in advance, the schedule for the roll intersection angle is determined to satisfy the shape. Therefore, it was not applicable as a method for determining a pass schedule for thick plate rolling where the number of passes is variable. The object of the present invention has been made in view of the above-mentioned actual state of the prior art, and
When rolling plate materials using a pair-cross rolling mill, the original capacity of the rolling equipment is utilized to the fullest throughout all passes, achieving high-efficiency rolling with the minimum number of passes, and the thickness of the pair-cross rolling mill is optimized to achieve the optimum rolling shape. The object of the present invention is to provide a method for rolling a plate.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for moving an upper roll and a lower roll, each consisting of a set of backup rolls and a work roll, in a plane parallel to the rolled material. In a pair-cross rolling mill that intersects with each other, the mechanical crown tolerance is calculated from the shape in each pass, and based on this calculated value, the reduction amount and intersection angle schedule for the shortest number of passes that satisfy the shape are cumulatively calculated. The maximum allowable rolling load is determined by

[0006]

[Operation] According to the above-mentioned means, the shape, crown, and reduction amount (load) schedule of the rolled material are simultaneously determined for each pass according to the shape control ability for all passes, and the accumulation calculation is performed using the optimum value for each pass. By doing this, a schedule for the reduction amount and the intersection angle for the shortest number of passes that satisfies the shape is calculated. As a result, the shape is satisfied in all passes, and a rolling schedule is determined based on the maximum capacity of the rolling equipment. Further, since the number of passes is automatically adjusted according to the shape control ability, the ability to vary the number of passes in the reversing rolling mill is fully utilized.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing an overview of the process for realizing the thick plate rolling method according to the present invention, and FIGS. 2 and 3
is a flowchart showing details of the processing in FIG. 1, and FIG. 4 is a flowchart showing details of the processing in FIG.
FIG. 2 is a block diagram showing an example of the configuration of a control system for realizing the processing of FIG. First, the configuration of FIG. 4 will be explained. Here, details of the process computer 1 with the business computer 2 as the host computer are shown. The process computer 1 is a finishing pass schedule calculation unit that calculates schedules such as plate thickness and cross angle for each pass in advance with the support of the business computer 2 and determines the process contents of the entire finish rolling pass before rolling starts. 1
1. Setting the schedule obtained by the roll profile estimation calculation section 12, which performs calculations for estimating the roll profile, and the finishing pass schedule calculation section 11, to the finishing plant controller 4, which will be described later, while actually rolling the plate for each pass. A finishing adaptive control calculation unit 13 that transmits values and performs learning calculations in real time to feed forward actual information between each pass to the next pass, and performs correction calculations for more accurate next pass settings; The error in the predicted value is calculated based on the actual plate thickness measurement value of the gamma ray plate thickness gauge 2 that detects the plate thickness of the subsequent workpiece 5 and the actual calculated value by the finishing adaptive control calculation unit 13, and the predicted value is calculated for the next pass and subsequent passes. The finishing learning calculating section 14 serves to improve control accuracy by making modifications to the path schedule calculation and the adaptive control calculation. The finishing adaptive control calculation unit 13 receives set values for the next pass (roll gap set values, roll cross angles, etc.) during rolling, and uses the finishing values to actually drive the finishing rolling mill 3 based on the values. A plant controller (finishing DDC) 4 is connected, and each of the rolling reduction value setting value, cross angle setting value, bender pressure setting value, target value crown setting value, and crown control coefficient given from the finishing adaptive control calculation unit 13 is connected. The rolling reduction of the pair cross rolling mill 3 is controlled according to the following.

FIGS. 5 and 6 are a plan view and a side view showing details of the finishing rolling mill 3. As shown in FIG. 5, a pair of upper work rolls 6a can be used to sandwich the workpiece 5 from above and below.
, lower work rolls 6b are arranged in a crossed manner. Each roll is arranged at an angle θ in the horizontal direction with respect to a line perpendicular to the traveling direction of the workpiece 5. An upper backup roll 7a is arranged parallel to the upper side of the upper work roll 6a, and a lower backup roll 7b is arranged parallel to the lower work roll 6b below the lower work roll 6b. In the figure, b is the width of the material to be rolled, Dw is the work roll diameter, θ is the 1/2 roll intersection angle, Sc is the roll spacing at the center of the plate, and Se is the roll spacing at the edge of the plate. ing. As is clear from FIGS. 5 and 6, the roll interval Sc at the center part of the board
On the other hand, the roll interval Se at the plate edge portion becomes wider as the roll crossing angle becomes larger, and the larger the roll crossing angle becomes, the larger the crown ratio becomes. However, as described above, in order to flatten the shape of the rolled material, it is necessary to suppress the plate crown change for each pass within a certain range, and it is not possible to take a large roll intersection angle at once. Furthermore, as shown in FIG. 4, a load cell 8 is provided to detect the rolling load of the upper work roll 6a, and a thermometer 9 is further provided to detect the surface temperature of the workpiece 5 after rolling. It is being

Next, the operation of the control system shown in the configuration of FIG. 4 will be explained with reference to the flowcharts of FIGS. 2 and 3. Note that S in the figure means a step. In the pass schedule determination method according to the present invention, first, the target final pass exit side plate thickness and plate crown amount are set (S21
). Next, after briefly assuming the finishing temperature and finishing direction of the final pass (S22, 23), the rolling reduction schedule and roll crossing angle schedule are sequentially set for each pass from the downstream pass to the upstream pass using the following calculations. decided at the same time. This target final pass exit plate thickness is sequentially increased by a constant value with the upper limit being the plate thickness of the rolled material sent from rough rolling. For example, if the thickness of the rolled material sent from rough rolling is 50 mm,
The target thickness is set as a target value, such as 10 mm, 12 mm, 15 mm, etc. That is, first, it is determined whether or not the current pass is a descaling execution pass (S24), and then the temperature and planned rolling speed of the entrance side (biting side) of the current pass are assumed (S25, 26). ). Here, from the plate width and outlet side plate thickness of the rolled material, the upper and lower limits of the allowable steepness of this pass and the target values (λmax, λmin, λaim, respectively) are calculated.
) is given. This λaim is basically 0, and λmax,
The λmin value is a parameter representing the allowable shape range for each rolled material size, and is determined empirically depending on the operating conditions. Using this λ value, Δε=(π/2)2 ・λ2
...From (1), calculate the allowable elongation strain difference and the target elongation strain difference, and further, Cin/hin=Cout /
hout −Δε/ξ+α

According to (2), the max (maximum value), min (minimum value), and aim (target value) of Δε are given, and the allowable range and target value of the plate crown ratio on the entry side are calculated (S27). However, Cin: Inlet side plate crown hin: Inlet side plate thickness Cout Output side plate crown hout Output side plate thickness Δε: Elongation strain difference ξ: Value expressing shape sensitivity (shape change system) α: Shape change correction system. Here, the max and min of (Cin/hin)
, aim, the allowable range and target value of the mechanical crown MCK, which is restricted from the shape in the current pass, are calculated using the following equation (S28). MCK=1/(1-η) ・{Cout
-η・hout・(Cin/hin)}…(3)
(However, η is the crown genetic coefficient)

On the other hand, the mechanical crown MCh from the rolling load and equipment allowable capacity is calculated by rolling load P, roll bending load F
Estimation calculation can be performed using the following equation using the roll intersection angle and roll profile. MCh=c1・P+c2・F+E
+c3...(4) Here,
P: Rolling load F: Roll bending load E: Mechanical crown amount formed by roll intersection angle c1: Mechanical crown influence coefficient due to rolling load c2:
Mechanical crown influence coefficient c3 due to bending load: This is the amount of mechanical crown formed by the local profile. Note that if there is no roll bending control device, the second term in equation (4) can be omitted, and if there is no roll crossing device, the third term in equation (4) can be omitted to reduce the equipment load. Mechanical crown MCh can be calculated. In equation (4), the maximum rolling load P
max and the minimum crossing angle 2θmin, MCh becomes maximum, and conversely, when the minimum rolling load Pmin and the maximum crossing angle 2θmin, the MCh becomes maximum.
When θmax, MCh is the minimum, and the mechanical crown tolerance range from the equipment load can be determined (S29). (
The range that satisfies both the mechanical crown tolerance range from the shape according to equation (3) and the mechanical crown tolerance range from the equipment load according to equation (4) is determined as the true mechanical crown tolerance range in this pass. Furthermore, modify so that MCkaim exists within this range,
A true mechanical crown target value MCaim is determined (S30).

Next, on the premise of achieving MCaim, the optimal combination of rolling reduction r, roll crossing angle 2θ, and bending load F is determined at the same time (S31
). At this stage, each value for the initial target thickness value (here, 10 mm) is determined. That is, if P=fp(r) E=fe(2θ), then from equation (4), MCaim =c1・fp(r)+c
Since 2・F+fe(2θ)+c3, r=fr(MCaim, 2θ, F)
... (5) Under certain conditions, the rolling reduction r can be searched and determined using 2θ and the bending load F. In Equation (5), 2θ and bending load F are determined so that the rolling reduction r is maximized because the operation is generally aimed at high-efficiency rolling. It is also possible to reflect other operating conditions using an evaluation function or the like, and to find the optimal combination by linear programming or the like. After determining the rolling reduction rate r for this pass, calculate the inlet side plate thickness, estimate the amount of temperature drop at the outlet side of this pass including the temperature change in the roll bite (S32), and re-calculate the plate temperature at the time of biting. calculate. Next, using the temperature, more accurate rolling load and rolling torque are calculated (S33, 34), and the load is checked (
After S35), the temperature, load, and crown calculations for the next upstream pass are repeated (S36, 37, 38, 40).
. By accumulating the above calculations for each pass from the downstream pass to the upstream pass, the pass schedule is determined sequentially, and the final calculation is repeated for passes where the pass entrance thickness exceeds the planned thickness at the start of rolling. end. When creating this pass schedule, if the planned thickness at the start of rolling cannot be changed, perform load distribution correction calculations as necessary, correct the plate thickness schedule, complete the calculation, and determine the entire pass schedule. do.

Next, an example will be shown in which a pass schedule for a rolled material is determined according to the above-described procedure of the present invention. (Example 1) A pass schedule for rolled material was calculated under the following preconditions. Final target thickness: 6.0mm Final pass exit plate crown amount: 0.02mm plate
Width: 3500mm Finishing temperature of final pass: 750℃ Rear direction finishing descaling execution pass: 1st pass and 3rd pass from the initial pass Maximum cross angle: 0.585° This prerequisite is based on the actual online process computer. In calculations, the top business computer 2
The information is transmitted as rolling material information, or is given as patterned information depending on the operating conditions. Then, by the following calculations, the roll reduction schedule and the roll crossing angle schedule were simultaneously determined for each pass sequentially from the downstream pass to the upstream pass. Here, the calculation process for the final pass (calculation start pass) is shown using a numerical example. [Assumption of temperature on the entry side (biting side)] Assume that the amount of temperature drop is 30°C, and the assumed biting temperature on the entry side is 780°C. [Assumption of planned rolling speed] The standard mill speed is set to 100 rpm based on the plate width of the rolled material and the exit side plate thickness. [Upper and lower limit range of allowable steepness and target value] λmax = 0.
4% λmin = -0.4% λaim = 0. (This is a parameter that represents the allowable shape range for each rolled material size, and is determined by an experienced person according to the operating situation using a table value.) [Calculate allowable elongation strain difference and target elongation strain difference] Δε= according to formula (1) (π/2)2 ・λ2 Δεmax =0.
004% Δεmin = -0.004% Δεaim = 0 [Calculate the allowable range and target value of the plate crown ratio on the entry side] (
2) According to the formula, Cin/hin=Cout/hout
−Δε/ξ+α α=0.15 ξ=0.61 Cout /hout =0.03% (Cin/hin)max=0.49%min=0.4
8% aim=0.48% [Calculate the allowable range and target value of mechanical crown constrained by shape] From formula (3), MCK=1/(1-η)・{Cout
-η/hout ・(Cin/hin)} η=0.702 MCKmax=0.00mm min=0.00mm aim=0.00mm [Mechanical crown tolerance range from rolling load and equipment allowable capacity] Pmax = 6500ton Pmin = 2200 ton θmax = 0.585° θmin = 0.000° Assuming F = 130 ton, from equation (4), MCh = c1・
P+c2・F+E+c3 MCchmax = 0.72 mm MCmin = 0.66 mm Here, the roll bending load was set to a fixed value on the assumption that it was not preset. [True mechanical crown tolerance range, target value MCaim
] MCmax = 0.00mm MCmin = 0.00mm MCaim = 0.00mm [Search and determine rolling reduction ratio r, roll crossing angle 2θ, and bending load F] In equation (5), the maximum rolling reduction is determined in order to achieve high efficiency rolling. When searching for the rate, under the condition of fixed F, θ=θma
When x==0.585°, r=0.1597(
=rseek) is obtained. [Calculate entrance side plate thickness] From hin=hOUT/(1-r), hin=7.1
4 mm [Calculate estimated temperature drop on exit side of pass] Temperature drop = 15°C Plate temperature at biting = 765°C [Calculate rolling load and rolling torque] P = 5420 ton torque = 198 ton. m, both within the equipment capacity. [Estimate calculation of temperature drop on pass entrance side] Temperature drop amount = 21°C. Plate temperature at exit side of previous pass = 786°C or above, the calculation of temperature, load, and crown for one pass is completed. By accumulating the above calculations for each pass from the downstream pass to the upstream pass, the pass schedule is determined sequentially, and the final calculation is repeated for passes where the pass entrance thickness exceeds the planned thickness at the start of rolling. end. In this example, the pass schedule for all passes was calculated assuming that the planned thickness at the start of rolling was 50 mm. The results are shown in comparison with the conventional method in FIGS. 7, 8, and 9. Both methods have the same shape adjustment ability using the roll cross function, but in the pass schedule of the conventional method, both cross and rolling load do not reach the maximum capacity of the equipment, resulting in an increase in the number of passes. Therefore, in the present invention, since the schedule calculation is performed by searching for the maximum allowable value, it is possible to achieve the shortest number of passes while maintaining the shape. In addition, compared to the conventional method, the disadvantage of discontinuity in the rolling load in the downstream pass of shape adjustment and the upstream pass of full load in the conventional method is eliminated by calculation that is consistent with all passes, and a smooth rolling load trend can be obtained. It will be done. In the past, for shape adjustment, it was necessary to reserve several passes on the end side of all the passes as shape adjustment passes, but this becomes unnecessary in the present invention.

(Example 2) A pass schedule for rolled material was calculated based on the following preconditions. Final target thickness: 20.0mm Final pass exit plate crown amount: 0.00mm plate
Width: 3500mm Finishing temperature of final pass: 850℃ (finishing in rear direction) Descaling execution pass: 1st pass from initial pass Maximum cross angle: 0.000° (no cross function) Maximum rolling load:
4,000 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.

(Example 3) A pass schedule for rolled material was calculated based on the following preconditions. Final target thickness: 45.0mm Final pass exit plate crown amount: -0.20mm plate
Width: 1500mm Finishing temperature of final pass: 850℃ (finishing in rear direction) Descaling execution pass: 1st, 3rd, and 5th pass from initial pass Maximum cross angle: 0.900℃ Maximum rolling load: 6000ton Maximum torque: 420ton Rolling start Planned thickness at time: 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 consisting of a set of backup rolls and work rolls, can be moved relative to each other in a plane parallel to the rolled material. In a paired cross rolling mill, the allowable mechanical crown range is calculated from the shape in each pass, and based on this calculated value, the schedule for the reduction amount and crossing angle for the shortest number of passes that satisfies the shape is calculated to achieve the maximum allowable rolling. Since the load is determined so that the shape is satisfied in all passes, and the schedule that can be rolled is determined based on the maximum value of the rolling equipment capacity. Further, since the number of passes is automatically adjusted according to the shape control ability, the ability to vary the number of passes in the reversing rolling mill is fully utilized.

[Brief explanation of the drawing]

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

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

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

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

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

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

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

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

FIG. 9 is an exit plate thickness-rolling load characteristic diagram showing the results of FIG. 7 in a graph.

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

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

[Explanation of symbols]

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

Claims (1)

[Claims] Claim 1: In a pair-cross rolling mill in which an upper roll and a lower roll, each consisting of a set of backup rolls and a work roll, are relatively crossed in a plane parallel to the rolled material, the shape in each pass is The mechanical crown permissible range is calculated from the above, and based on this calculated value, the reduction amount and intersection angle schedule for the shortest number of passes that satisfy the shape are determined by cumulative calculation so that the maximum permissible rolling load is achieved. A thick plate rolling method using a pair cross rolling mill.