JPH06154832A - Method of automatically controlling plate-thickness in pair cross rolling - Google Patents

Abstract

PURPOSE:To improve the accuracy of plate thickness and to reduce its camber by calculating an actual rolling load and a difference between left and right loads and controlling the plate thickness and wedge based on these detected values and calculated values. CONSTITUTION:When the calculation of setting to the succeeding material is learnt and corrected from a pass information of the preceeding pass, a load given actually by the material 7 to a mill is fed back to control the plate thickness set values for controlling the plate thickness on and after the succeeding pass become high in reliability and, as a result, the rolled plate thickness becomes high in accuracy. Besides, when the difference between elongations in the right and the left of the mill in the preceeding pass is enumerated by the detecting signal of a load cell 1, a roll gap between the right and the left is set so that the deviation of the elongation of the mill is preset and canceled and the camber can drastically be restrained. Accordingly, a load given actually by the material to the mill is fed back to control the plate thickness and the wedge, the accuracy of a rolled plate thickness is elevated and the camber is drastically restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick plate rolling using a reversing mill capable of independently rolling upper and lower roll chocks in the horizontal direction of rolling, and relates to a rolling method for automatically controlling the plate thickness. It is a thing.

[0002]

2. Description of the Related Art Conventionally, in a pair cross rolling machine for performing reverse rolling by relatively crossing a roll set in which a backup roll and a work roll are paired in a plane parallel to a rolled material, a strut generated during rolling is used. Since the load applied to the left and right rolling load detection load cells is unbalanced due to the influence of the force, a method for controlling the plate thickness independently by using a thrust load cell while eliminating the influence (Japanese Patent Publication No. 63-23851). ) Is proposed.
Also, a method of installing load cells above and below to reduce the effect of mill hysteresis and control the plate thickness (Japanese Patent Publication No. 63-11).
28). Furthermore, the true rolling load (left-right difference,
There has been proposed a method for calculating and controlling the sum of left and right. In addition, the thrust load generated in the roll axial direction is
Rolling is performed while detecting with docel and using for load bearing check on equipment.

[0003]

In the conventional technique for canceling the load imbalance by the above-mentioned upper, lower, left and right load cells, the control can be performed on the assumption that the upper and lower mill rigidity are equal. Is a deviation of the detected load depending on the condition of the contact surface of the roll chock, the condition of bearing maintenance, etc., so the imbalance of the detected load cannot be separated from the strict load due to the thrust or the eccentric load due to the deformation behavior of the rolled material. There is.

When there is a difference in the amount of upper and lower mill springs, the load unbalance effect due to the thrust moment is not uniform, so the actual left and right mill elongation difference changes, which is why reverse rolling is the main cause. In the case of thick plate rolling, there is a problem that it is difficult to control the wedge of the material to be rolled because the propensity is reversed during forward rotation and backward rotation.

An object of the present invention is to accurately separate and cancel the above-mentioned load imbalance in the case of automatically controlling the plate thickness so that the plate thickness and the wedge can be accurately controlled.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the true rolling actual load and the left-right load difference are calculated from the detection values of the vertical load detection load cell and the thrust load detection load cell, excluding the influence of the thrust load. Then, the plate thickness and the camber are controlled based on these detected values and calculated values.

[0007]

The operation of the present invention will be described in detail below. First, the content of the calculation of the true actual rolling load and the left-right load difference will be described. Figure 1 shows the front view of the pair cross rolling mill,
The load which acts on a rolling mill and a roll at the time of material rolling is shown. First, in this rolling mill, during material rolling, a rolling load P in the vertical direction and a thrust load F in the axial direction of the roll are generated from the material.

The loads P and F generated from these materials are detected by the load cells 1 and 6 via the work roll 5 to the backup roll 2 or the work roll 5 to the work roll chock 4, respectively.

During actual rolling, when the material 7 to be rolled is displaced from the center position in the axial direction of the roll by a, or there is a lateral plastic resistance deviation of the material, P
Are not always evenly distributed on the left and right. At this time, the basic equilibrium condition equations (1) to (1) to
(8) is established.

[Rolling load] On-road top PT _WS + PT _DS = P + PF _T ... (1) Lower PB _WS + PB _DS = P-PF _T ... (2) Off-road top PT _WS + PT _DS = P −PF _T・ ・ ・ (3) Lower PB _WS + PB _DS = P + PF _T・ ・ ・ (4) [Thrust load] Upper F = FT _WR + FT _BUR + FT _HG・ ・ ・ (5) Lower F = FB _WR + FB _BUR + FB _HG・ ・ ・ (6) [Rotation moment balance] Upper F [d + (DB / 2) + DW] -FT _WR [d + (DB / 2) + (DW / 2)]-FT _BUR d-PT _DS (L / 2) + PT _WS (L / 2) -Pa = 0 ... (7) Lower F [e + (DB / 2) + DW] -FB _WR [e + (DB / 2) + (DW / 2)]-FB _BUR e−PB _DS (L / 2) −PB _WS (L / 2) + Pa = 0 (8) The symbols in the formulas (1) to (8) are as shown in FIG. Using these load unbalance formulas, the material 7 is determined from the load cell load (detection value of load cells 1 and 6) that can be actually observed.
A method for detecting the true load P received from the vehicle will be described below.

In the thrust load equations (5) and (6),
The component forces acting on the work roll 5 and the backup roll 2 are expressed by using distribution coefficients α and β, respectively. FT _WR = αF (9) FT _BUR = βF (10) FT _HG = (1 −α−β) F (11) Substituting these equations (9), (10), and (11) into equation (7) and rearranging: F [d + (DB / 2) + DW] -αF [d + (DB / 2) + (DW / 2 )] −βF · d− (L / 2) (PT _DS −PT _WS ) −Pa = 0 PT _DS −PT _WS = F · (1 / L) [2d (1−α−β) + DB (1−α) ) + DW (2-α)] + (2Pa / L) (7 ').

Here, assuming that the thrust load is a force F _THG ≈ 0 received by the housing itself, on the other hand, DB ≈ 2DW
Since it _{is, PT DS -PT WS = F ·} (DW / L) becomes a (4-3α) + (2Pa / L ) ··· (12). For example, when the thrust load applied to the work wheel 5 (WR) is observable, PT _DS -PT _WS = FT _WR (DW / L) (4-3α) / α + (2Pa / L) ... It can be represented by (13).

Similarly, rearranging the lower side, PB _DS + PB _WS = -F (1 / L) [2e (1-α-β) + DB (1-α) + DW (2-α)] + 2Pa / L.・ From (8 ') PB _DS- PB _WS = -F ・ DW (4-3α) / L + (2Pa / L) ... From (14) PB _DS- PB _WS = -FB _WR (DW / L) (4-3α / α) + (2Pa / L) (15), and when the equations (12) and (14) are combined, the right side first
It is possible to offset the term (thrust load effects section), and _{(PT DS -PT WS) + (} PB DS + PB WS) = (4Pa / L) ··· (16). The true rolling load difference due to off-lock can be calculated from the equation (16).

Further, the second term on the right side (off-center influence term) can be canceled by the difference between the equations (12) and (14), and (PT _DS −PT _WS ) − (P B _DS + PB _WS ) = 2F · [DW (4-3α) / L] (17), and the unbalanced force due to the thrust force can be extracted.

For example, when the thrust load F _WR applied to the work wheel 5 (WR) can be detected or calculated, [(PT _DS −PT _WS ) − (P B _DS −P B _WS )] / 2 = F _WR (DW / L) (4-3α / α) (18), and the α value can be estimated.

From the mill dimension, the diameter of the work wheel DW = 985, the distance L between the left and right bearings L = 5918 is substituted to express the left side ≈ΔPm. Α = 4 / [(L.ΔPm) / (F _WR. DW) +3] ≅4 / [(6ΔPm) / (F _WR +3)] (19) For example,

[0017]

[Equation 1]

[0018] Further, when the true thrust load F received from the material is expressed by the equations (19) and (9), F = (3ΔPm / 2) + (3F _WR / 4) (20) F≈375 ton.

The thrust load applied to the backup roll 2 (BUR) is F _BUR = (3ΔPm / 2)-(1F _WR / 4) (21), and the influence of mill hysteresis The true rolling load sum removed can be easily recognized by combining the expressions (1) to (4).

Summarizing the above relationships, the true rolling load sum excluding the influence of frictional force (hysteresis) in the mill rolling system P = (PT _DS + PT _WS + PB _DS + PB _WS ) / 2 (22) Thrust load effect receiving from excluded material true right rolling load difference _{P REF = (PT DS -PT WS} + PB DS -PB WS) / 2 ··· (23) receives from the material 7 true thrust load F = (3ΔPm / 2) + (3F _WR / 4) ・ ・ ・ (24) Thrust load received by the backup roll 2 F _BUR = (3ΔPm / 2)-(1F _WR / 4) ・ ・ ・ (25) The work roll 5 The received thrust load distribution ratio α = 4 / [6 (ΔPm / F _WR ) +3] (26) can be obtained by such calculation. In the present invention, the vertical load and the lateral load are detected by using the rolling load detecting load cell 1 arranged vertically and horizontally and the thrust load detecting load cell 6 acting on the work wheel 2, and the detected value and the above (22 ) To (26), the true load P and the left-right load difference P _REF received from the material 7 are calculated, and the thrust load F and the like are calculated.

Next, the effect of load imbalance on the difference between the left and right mill elongations will be described below. The spring constants of the upper and lower backup roll support parts are set to the workside (WS) /
Drive side (DS) KT _D , KT _W , KB respectively
_{With D} and KB _W , the rolling load detection single load cell load is directly reflected on the elongation amount.

[0022] The growth of the DS elongation amount _{S D = (PT DS / KT} D) + (PB DS / KB D) WS elongation amount _{S W = (PT WS / KT} W) + (PB WS / KB W) DS-WS Quantity difference S _REF = S _D -S _W S _REF = [(PT _DS / KT _D )-(PT _WS / KT _W )] + [(P _{B DS} / KB _D )-(P _{B WS} / KB _W )] = [ _{1 (PT DS -PT WS) /} KT D ] + _{[1 (PB DS -PT DS) /} KB D ] + PT _{WS [(1 / KT D) - (} 1 / KT W) ] + PB _WS [(1 / KB _D )-(1 / KB _W )] ... (27) For example, when the left and right mill stiffnesses are equal, KT = KT _D = KT _W , KB = KB _D = KB _W , and the equation (27) is S _REF = [1 (PT _DS −PT _WS ) / KT] + [1 (P B _DS −PT _DS ) / KB] S _REF = [P _REF (1 / KT) + (1 / KB)] + [ΔPm ( 1 / KT)-(1 / KB)] (28) where ΔPm is (24) From the formula, ΔPm = [(2/3) −α] F (29), and (1 / KT) + (1 / KB) = 1 / K, S _REF = (P _REF / K ) + [F (2/3) -α] [(1 / KT)-(1 / KB)] (30), and if the spring constant is known, the true differential load P _REF and thrust load If F can be estimated, the deviation S _REF between the left and right mill stretch amounts can be estimated.

The reflection (feedback: FB) of the calculated load and the like on the plate thickness and wedge control is shown below.

The FB for control can be roughly classified into two from the control timing.

(1) Reflection in preset control between passes (2) Reflection in dynamic control during roll bite In the following, the reflection in preset control between passes (1) will be described. FIG. 2 shows a system configuration for performing this preset control. The process computer 11, which has received the information necessary for rolling by the business computer 12,
First, the reduction schedules for all the passes are determined in advance (pass schedule calculation unit).

Next, at the timing of actually rolling the sheet, preset information for controlling the rolling mill for each pass is calculated by the "adaptive control calculator", and the information is transmitted to the sequencer 10. The sequencer 10 receives the set value for each pass from the process controller 11 and converts the set value into a signal for performing the actual rolling position control, and drives the hydraulic equipment and electric motor of the rolling mill to set the predetermined position and pressure. Let it set. The above is the outline of the preset control. In the process computer 11, when the calculation is performed, the rolling record of a pass including the immediately preceding pass or a pass before the previous pass and the detection value of the sensor are stored, and the learning calculation unit and the roll wear that are reflected in the setting calculation of the pass, It also has a roll profile calculation unit that estimates the change over time due to thermal expansion.

Next, the reflection of the above-mentioned (1) in the preset control in the setting calculation of the process computer 11 will be described in detail.

The process computer 11, which has received the detection information of the load cells 1 and 6 in the previous pass, uses the equations (22) to (26) shown above to determine the true load from the material in the previous pass. calculate.

Here, the true rolling load sum: P
m act (= P) True rolling load difference: ΔPm act (= P _DS −
P _WS ) Thrust load from material: Fact (= F) On the other hand, the load in the previous pass is estimated and calculated from the rolling record information such as the actual reduction amount and temperature in the previous pass, and the estimated load and the load cell The difference value with the load calculated based on the detected values of 1 and 6 is calculated, and the load predicted value of the next pass is corrected based on this difference value. That is, the weight prediction is learned and updated.

That is, assuming that the calculated values of the previous pass (values by which the load is estimated and calculated) are Pm cal, ΔPcal, and Fcal, respectively, the load sum error E _p = Pm act / Pm cal load difference error E _ΔP = ΔPact −ΔPcal frust The load error E _F = Fact / Fcal is calculated, and P _EST '= P _EST × sE _p ΔP _EST ' = ΔP _EST + sE _Δp F _EST 'for the predicted values P _EST , ΔP _EST , and F _{EST of} the next path. = F _EST × sE _F Modify with the formula. Here, s means a value after the smoothing of the error, and for example, when the error = 1.10, 5
If 0% learning is reflected, it means reduction to 1.05.

The above is the pass information of the previous pass (rolling actual value &
This is the content to learn and correct the setting calculation for the next material from the detected value). As a result, the load that the material actually gives to the rolling mill (especially the difference between the left and right loads) is fed back to the plate thickness control, and the reliability of the set value for plate thickness control after the next pass becomes high. As a result, the rolled plate thickness accuracy is increased.

On the other hand, since the left and right mill elongation difference of the previous pass is calculated by the equation (27) from the detection signal of the load cell, the (27) is obtained from the left and right mill elongation difference and the actually measured thickness wedge amount or camber amount. Learn and correct the upper, lower, left, and right mill rigidity (spring constant) in the equation. Next, at the time of calculating the roll gap setting for the next pass, P _REF : True rolling load difference F: Thrust load predicted in the next pass is calculated, and the mill elongation difference due to the load imbalance is calculated by the formula (30). , The left and right roll gaps are set in advance so as to cancel out the mill elongation deviation by presetting. As a result, camber is greatly suppressed.

[0033]

【Example】

(Example 1) When the actual detected load of the previous pass is PT _DS PT _WS PB _DS PB _WS F _WR 2222ton 2101ton 2105ton 2231ton 182ton, the true rolling load from the formula (22) P = 4330ton The true rolling load from the formula (23) Rolling load difference P _REF = -5ton From formula (24), the true thrust load received from material ΔPm = 124ton F = 323ton Further, the thrust load sharing received by the work wheel is α
= 0.563. For the true load group received from the above materials, the setting calculation of the next pulse was learned and corrected from the actual reduction amount of the previous pass. That is, when Pcal = 4250 ton ΔPcal = 0 Fcal = 350 ton, then from E _P = 0.981 sE _p B
= 0.99 E _ΔP = 5, sE _Δp = 3 E _F = 0.923, and sE _F = 0.95.

Next, the predicted value of the next pass was learned and corrected.

P _EST = 4110ton is 4069t
on (corrected value) ΔP _EST = 0 is 3 ton (corrected value) F _EST = 315 ton is 299 ton (corrected value) On the other hand, regarding the mill elongation difference due to the load unbalance in the previous pass, KT = KT _B = KT _W = 1509 ton / mm KB = KB _D = KT _W = 1509 tons / mm K = 969, and path before S _REF = (2222-2101 / 1509) +
(210−2231 / 2708) S _REF = 0.0337mm Then, in the next pass, from the formula (30), S _REF = (3/969) + [299 × {(2/3) -0.563} {(1/1509 )-
(1- / 2708)}] × (-1) S _REF = -0.02758 mm In the above formula, the fact that the second term is true is a characteristic of reverse rolling.

Table 1 shows the load and roll gap performance for each pass when rolling is actually carried out in the above-mentioned mode.

[0037]

[Table 1]

As shown in Table 1, the actual rolling load, the behavior difference loads DS-WS is reversed at the upper side and lower side is generated in the reverse rotation and forward rotation, positive as S _REF at the influence Reverse milling deviations occur alternately.

For this reason, a camber occurs in the direction in which the front part of the plate bends to the WS side during normal rotation of the mill, and conversely, it bends to the DS side during reverse rotation.
As the rolling pass progresses, this bending diverges in the maximum direction, and in conventional rolling, the camber becomes large as shown by the solid line in FIG.

On the other hand, S _REF shown in Table 1 is predicted just before each pass for each pass as in the first embodiment, and the amount is determined in advance as the roll gap imbalance value.
The camber was greatly suppressed, as shown by the dotted line in FIG.

[0041]

As described above, according to the present invention, the load actually applied to the rolling mill by the material is fed back to the plate thickness and the wedge control, the rolling plate thickness accuracy is improved, and the camber is significantly suppressed. To be done.

[Brief description of drawings]

FIG. 1 is a front view showing an outline of one rolling mill to which the present invention is applied.

FIG. 2 is a block diagram showing a rolling control system of the rolling mill shown in FIG.

FIG. 3 is a graph showing a camber generated in the conventional thick plate rolling and a camber generated in the embodiment of the present invention.

[Explanation of symbols]

1: Load cell 2: Backup roll (BUR) 3: Backup roll bearing 4: Work wheel
Bearing 5: work roll (WR) 6: load cell 7: rolled material 8: rolling down device 9: work roll bender 10: sequencer 11: process computer 12: business computer

Claims (1)

[Claims] 1. A rolling mill that reverse rolls by rolling a roll set in which upper and lower backup rolls and work rolls are paired in a plane parallel to a rolled material and performing reverse rolling. The actual rolling actual load excluding the influence of the thrust load and the left and right load difference are calculated using the load cell's detected value of the load cell and the load cell that detects the thrust load generated in the roll axial direction. An automatic strip thickness control method in pair cross rolling, characterized in that the strip thickness and wedge are automatically controlled based on the values.