JPH0364206B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a plate thickness control method, and in particular, to correct the set value using the actual measured values of the load at bottom drop, the rolling position, and the exit side plate thickness to minimize the off-gauge. This invention relates to a method for controlling plate thickness.

[Background of the invention]

By controlling the plate thickness and shape, the strip quality in steady state has been significantly improved. Furthermore, fully continuous rolling is being implemented for the purpose of saving labor and improving yield. Also, the plate thickness is not the conventional 0.2-0.3mm,
Ultra-thin rolling, which produces products with a thickness of 0.02-0.05 mm, began to be carried out.

However, since the plate thickness setup method is the same as the conventional method, the off-gauge length has hardly been improved. That is, the rolling load P _O is calculated using a mathematical model, and the roll heat up amount ΔS _O is estimated from the S _O after the roll rearrangement and the rolling time after the roll rearrangement.
A method is used to determine and set the rolling position S using equation (1).

S=h _O −P _O /K−S _O −ΔS _O ……(1) Here, h _O is the target plate thickness, K is the spring constant of the mill, or
Learning the rolling load P _O uses the plate thickness and rolling load during steady rolling, so at low speed immediately after setting,
This includes estimation errors for oil film, friction coefficient, etc., and has an error of 5 to 10%. Also, Figure 1 A, B
As shown in Figure 2, since the roll heat-up amount _ΔSO is estimated based on the rolling time after the roll replacement regardless of the rolling power, an error of about 20-60μ occurs in the 5 to 6 rolls after the roll replacement. In the figure, A shows an example where the load is relatively large, and B shows an example where the load is small. Further, as shown in FIGS. 2A and 2B, the spring constant of the mill changes depending on the plate width and the position of the hydraulic cylinder. Conventional board width correction is done by measuring offline, but
Since no correction was made using a hydraulic cylinder, an error of 50 to 200 μm occurred. Also, Figure 3A
As shown in ~C, the tip of the base material is approximately 50-300μ thicker than the nominal base material thickness. FIGS. 3A to 3C are illustrations of three typical patterns of variations in base material plate thickness. Therefore, we perform setting calculations based on the nominal base material thickness, and there is no error in the calculations, and the roll heat up amount,
Even if there is no error in the spring constant of the mill, the tip of the finished product will be thicker by an amount corresponding to the variation in the base material plate thickness.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the conventional learning control described above and to provide a method for controlling the thickness of a strip by turning on the gauge from the tip of the strip.

[Summary of the invention]

The plate thickness control method according to the present invention involves actually measuring the inlet side plate thickness, outlet side plate thickness, and rolling pressure at the bottom removal speed of the rolled material, and calculating the rolling pressure from a mathematical model based on the actually measured inlet side plate thickness and outlet side plate thickness. Calculate the correction coefficient Zp from the above measured rolling pressure and the rolling pressure of the above mathematical model, and use the above correction coefficient Zp when calculating the next schedule to correct the rolling pressure of the next rolled material, and calculate the corrected rolling pressure. The method is characterized in that the thickness of the next rolled material is controlled by the rolling position.

[Embodiments of the invention]

First, the basic idea of the present invention will be described.

When the speed is reduced to the bottom-out speed, the entry side plate thickness H _a ,
The exit side plate thickness h _a and rolling pressure P _a were actually measured, and H a and H _a at the same strip point were determined by tracking the strip.
Select h _a and P _a . The rolling pressure P _C is calculated using a mathematical model based on the actually measured H _a and h _a , and Z _p = P _a /
Calculate Z _p that becomes P _C , and when calculating the next schedule Z _p P _C
is used as the calculated rolling pressure. This eliminates oil film and friction coefficient estimation errors.

In addition, the rolling position S _a was actually measured while the strip was decelerated to the bottom removal speed, and h _a , P _a , and
Calculate S _O by (2) using S _a .

S _O =h _a −P _a /K ₁ −S _a (2) However, here, as the spring constant K ₁ , K ₁ actually measured at the tip of the strip described below is used. As a result, the S _O immediately before the next schedule setting is obtained by actual measurement, so that fluctuations in the amount of roll heat up until the next schedule setting are negligibly small.

Using the above Z _p P _C and S _O , calculate and set the next schedule reduction position S from equation (3).

S=h _O −Z _p P _C /K ₁ −S _O ...(3) However, h _O is the target plate thickness on the exit side. In equation (3), the thickness on the inlet side is the target plate thickness H _O and the mill spring constant K. ₁ uses the spring constant of the previous coil, so it is impossible to set the outlet side plate thickness variation Δh=0. Therefore, after setting, the mother plate thickness variation ΔH _a and the exit side plate thickness variation Δh _a rolling pressure variation ΔP _a are measured, and ΔH _a , ΔP _a , Δh _a at the same strip point are selected by tracking the strip (4) and ( 5) Calculate the spring constant K of the mill and the plasticity coefficient M of the material using the formula.

ΔP _a =KΔh _a ...(4) ΔP _a =M(ΔH _a −Δh _a ) ...(5) Figure 4 shows the relationship between equations (4) and (5). 1 indicates the material properties and its slope is the plasticity coefficient M, and 2 indicates the rolling characteristics of the mill and its slope is the spring constant K. Here, if ΔP _a =P ₂ −P ₁ ΔH _a =H ₂ −H ₁ Δh _a =h ₂ −h ₁ , equations (4) and (5) can be easily calculated.

Similarly, it can be easily calculated that the reduction correction amount ΔS for correcting Δh _a =h ₂ −h ₁ is expressed by equation (6).

ΔS = (K + M / K) × Δh _a ... (6) Immediately after learning K and M, based on the actually measured entrance plate thickness variation ΔH, use the formula (7) to calculate the reduction correction amount ΔS, perform the correction, and adjust the exit side plate thickness. The variation Δh can be set to 0.

∆S = (M/K) ∆H ... (7) This correction starts after the inlet thickness variation point reaches the outlet thickness gauge, and some off-gauge strips occur, but if K and M correction is not necessary. It is possible to calculate the thickness variation on the exit side using equations (8) and (9), and then use equation (6) to correct the rolling position after the set value.

h _a = P _a /K + S + S _O ...... (8) Δh _a = h _a - h _O ... (9) Also, if correction of M is not required, after the strip position after setting the reduction reaches the exit side thickness gauge It is possible to correct K using equation (4) and correct the rolling position using equation (6). Also, as the strip progresses,
It is also possible to correct the exit side plate thickness variation to 0 in three stages: correction of the reduction position immediately after setting, correction of the reduction position after K correction, and correction of reduction position after M correction.

FIG. 5 shows an embodiment of a six-high reversible rolling mill in which K and M corrections are not required. In Fig. 5, 1 is a rolling machine, 2 and 3 are thickness gauges, 4 is a rolling position detector,
5 is a load detector, 6 is a reduction position control device, 7 is (2)
8 is a rolling position _S calculation device based on the formula (3); 9 is a rolling pressure calculation device. Here, the rolling pressure P _C may be determined by calculation or may be a set rolling pressure stored in a table format. In that case, Z _p is similarly determined just before the end of the previous rolling and applied to the next schedule.

FIG. 6 shows an embodiment of a six-high reversible rolling mill in which roll heat-up, K and M corrections are performed. In Fig. 6, 1 is a rolling machine, 2 and 3 are thickness gauges, 4 is a rolling position detector, 5 is a load detector, and 6
7 is a rolling position control device, 7 is a S _O calculation device based on formula (2), 8 is a rolling position S calculation device based on formula (3), 9 is a rolling pressure calculation device, and 10 is (4 ), (5), (6),
This is a ΔS calculation device based on equations (8) and (9).

The explanation was given using a 6-high reversible rolling mill, but 2-high, 4-high,
Not only can plate thickness be corrected using the same method on a 20-high reversible rolling mill, but also plate thickness can be corrected using the same method on a tandem rolling mill equipped with two or more thickness gauges. However, in the case of a stand without a thickness gauge, it is sufficient to use the well-known mass flow formula to determine the stand exit plate thickness h _a and apply equations (2), (4), and (5).

Further, the control devices 7, 8, and 9 in FIG. 5 and the control devices 7, 8, 9, and 10 in FIG. 6 can be replaced with computers for control.

In addition, in a reverse mill, it is possible to enter on-gauge from slow rolling speed or sheet threading speed, and conventionally the on-gauge cannot be reached unless the rolling speed is 30-50% of the rolling speed.
It can be made up to 6m.

In addition, in a semi-continuous tandem rolling mill, it is possible to increase the on-gauge speed by increasing the threading speed, so the off-gauge can be reduced from 30 to 100 meters in conventional rolling mills to 5 to 100 meters.
Can be made 10m.

In addition, in a fully continuous tandem rolling mill, the off-gauge at the schedule change point can be reduced from 10 to 30 m to 2 to 3 m.

〔Effect of the invention〕

According to the present invention, off-gauge length can be reduced.

[Brief explanation of drawings]

Figure 1 shows the amount of roll heat up, Figure 2 A,
B is the spring constant of the mill, Figure 3 is the plate thickness deviation, and Figure 4 is the spring constant of the mill.
The figure is an explanatory diagram for calculating the mill spring constant and the plasticity coefficient M, FIG. 5 shows an embodiment of the present invention, and FIG. 6 shows another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Rolling mill, 2, 3... Plate thickness gauge, 4... Rolling position detector, 5... Load detector, 7... S _O calculation device, 8... Rolling down position S calculation device, 9... ...Rolling pressure calculation device.

Claims (1)

[Scope of Claims] 1. A method for controlling plate thickness in a cold rolling mill having at least a pair of rolling rolls and rolling a material to be rolled between the rolling rolls, comprising the following steps: Measure the exit side plate thickness and rolling pressure, calculate the rolling pressure from a mathematical model based on the actually measured entrance side plate thickness and exit side plate thickness, calculate the correction coefficient Zp from the above measured rolling pressure and the rolling pressure of the above mathematical model, When calculating the next schedule, use the correction coefficient Zp mentioned above to correct the rolling pressure of the next rolled material, and at the same time measure the rolling position at the bottom removal speed of the material to be rolled, and use the exit side plate thickness and rolling pressure of the same strip point to A cooling method characterized in that the rolling position immediately before setting the schedule is determined, the rolling position of the next schedule is corrected from this and the correction coefficient Zp, and the plate thickness of the next rolled material is controlled based on the revised rolling pressure and rolling position. Method for controlling plate thickness in inter-rolled materials. 2. In the rolling after the modification described in claim 1, the spring constant of the rolling mill and the plasticity coefficient of the material are calculated from the inlet side plate thickness, outlet side plate thickness, and rolling pressure detection value of the rolling mill, and the calculated A plate thickness control method in a rolling mill characterized by correcting the rolling reduction using a value.