JPS5922601B2 - Rolling mill control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to plate rolling in which the center of the plate width of the rolled material is intentionally shifted from the mill center to the work side or drive side (hereinafter, such rolling is turned off). This invention relates to a method of controlling a rolling mill called center rolling.

According to the conventional rolling mill control method, the roll pending force on the work side and the tribe side are applied so as to be equal in principle, but when this is applied during off-center rolling, the roll pending force is increased to 5 as shown in Fig. 1. This effect appears as a change in the roll gap that is symmetrical with respect to the center of the roll body length, so the deformation is asymmetrical when viewed from the center force of the strip width of the rolled material, causing a difference in the elongation rate on both sides of the rolled material, causing single waves and strip The bending makes normal rolling operations impossible.

The present invention advantageously solves these drawbacks, and an object of the present invention is to provide a rolling mill control method for realizing off-center rolling as a normal rolling operation.

On the same day, the applicant determined the necessary difference in the roll gap at no load on the work side and drive side so that the elongation rate on both sides of the rolled material would be approximately equal in off-center rolling, and When off-center rolling is performed using a rolling mill setting method characterized by different rolling reduction amounts and a rolling mill equipped with a roll bending device, the elongation rate on both sides of the rolled material is approximately equal. This invention relates to a rolling mill setting method characterized by determining the necessary difference in pressure ft between the work side and the drive side and the appropriate ratio of the roll pending force between the work side and the drive side, and providing a difference in roughness and tightening for each. He made an invention and applied for a patent.

To summarize these, the former setting method takes into account the asymmetric deformation that occurs in the rolling mill due to off-center rolling under individual rolling conditions, and then The work side drive side roll gap difference is determined and this is set in advance using the rolling reduction setting. The side roll gap difference is set, and the ratio of the roll pending force on the work side and drive side that does not cause a difference in the elongation rate on both sides of the rolled material is determined, and this appropriate ratio is determined. The settings must be set to satisfy the requirements.

Even when the rolling mill is set according to the above invention, during rolling, the shape of the plate crown plate of the input rolled material changes, and the deformation resistance in the width direction and longitudinal direction due to material accumulation, rolling speed, etc. Due to this variation, the shape of the plate crown plate of the outlet rolled material varies from the target value.

If this variation exceeds a permissible value, it is effective to control the shape of the crown plate using a roll pending force.

However, if we adopt the conventional method of varying the roll pending force by the same value on the work side and drive side, the resulting variation in roll gap will be symmetrical with respect to the mill center as shown in Figure 1, so This results in the problem that the growth rates at

In the present invention, in order to solve this problem, the ratio of the roll pending force on the work side and the drive side when the elongation rate on both sides of the rolled material is equal is determined,
The roll pending force is controlled so that the control amount satisfies the ratio, and the work side and drive side are corrected based on the prediction of the elongation rate difference on both sides of the rolled material caused by the roll pending force. We have invented a method to control the pressure reduction.

In the following, a method of determining the appropriate ratio of the roll pending force and a method of controlling the rolling force will be explained while showing a specific example.

The ratio of roll pending force that does not cause a difference in the elongation rate on both sides of the rolled material is determined as follows.

First, when the roll bending roller F on the work side is individually loaded by a unit amount, the increment 2Δyw of the roll gap at the plate end position on the work side of the rolled material, the increment 2Δy of the roll gap at the plate end position on the drive side, and the M) - Four basics of the roll gap increment 2Δy at the plate end position on the work side of the rolled material when the roll pending force FD on the eve side is individually loaded by a unit amount, the roll gap increment 2ΔyDp at the drive side plate end position Find the quantity.

These can generally be found as follows.

The deformation of the rolling mill when a pending force of F"W="1t"D=F2 is applied is calculated in detail, and the increment of the roll gap at the plate end position on the work side (F"w=FD=07
) - Ra increment) 2Δyw1, determine the roll gap increment 2ΔyD1 at the drive side plate end position, and then F
W=F3. When a penting force of FD=F4 (Fl・F4NF2・F3) is applied, the increment 2Δyw2 of the roll gap at the work side plate end position and the roll gap increment 2Δ”D2 at the drive side plate end position are determined.

The following relational expression is established between these and the four basic quantities described above due to the principle of superposition.

ΔyWI""l"Δyww tenF'2"ΔyDw =(
1) Δ”D to Fl ・Δ”WD×F2”ΔyDD −
(2) Δ3'W2"F3・Δ"WW 10F 4'Δ"
DW"(3)Δ"D2""F3・ΔywD+F4・Δy
DD...(4) Solving the above equations (1) to (4) simultaneously yields Δyww and ΔyDw.

ΔywD and ΔyDD are found.

If these basic quantities are warp force, then the ratio of roll pending force that does not cause a difference in the roll gap on both sides of the rolled material can be found from the following equation.

FW(Δyw−ΔyWD)=FI)(ΔyDD−
Δyrw>・(5) FIG. 2 shows a specific numerical example.

The axis of the work roll when a rolled material with a width of 914 m is rolled at the mill center with a rolling load of 1016 tons (uniform load distribution in the width direction) using a four-high rolling mill with the dimensions shown in Figure a. The results of calculating the core deformation by taking into account the deflection of the bank unroll and the flattening deformation between the work roll and the back unroll are shown in the same figure.

In addition to these deformations in the rolling mill, there are deformations due to nozzling and work roll flattening, but the effects of these are small and will be ignored here.

Furthermore, although the state shown in FIG. 2a is not off-center rolling, the deformation of the rolling mill can be approximated by a spring model, so there is not enough force to extract the deformation caused by the roll pending force.

Figure 2 shows the case of FW=FD20 and FW=100.
The axial center deformation is shown in two cases: ton/chock s Fl) = O. Based on these results, the appropriate ratio of FW and FD during off-center rolling, which is shifted 400 mm from the chemil center of the rolled material, is determined. .

If we consider 100 tons/cho ck as a unit load, in this case the rigidity of the rolling mill is symmetrical, so from Fig. 2 A
Yww.

It is possible to read ΔywD, ΔyDD, and ΔyDw.

Substituting these values into equation (5) yields '.

Therefore, in this case, the work side roll pending force control amount ΔFw and the drive side control amount Δ
Control may be performed so that the FD satisfies the following equation.

) The above example is an increase pending force (
The above discussion can also be applied to daily pending force (force in the direction of closing the roll gap) by simply adding a negative sign to the pending force.

Next, a method of compensating for the elongation difference on both sides of the rolled material caused by the rolling force by rolling reduction control will be explained.

Consider the case where the center is moved by ΔX to the work side.

In the initial settings, it is assumed that the elongation rate on both sides of the rolled material is equal, and the roll pending force on the work side is set to ΔF in order to control the shape of the plate crown during rolling.
w, Drive side shall be increased by ΔFD.

The signs of ΔFw and ΔF”D indicate changes on the increase side as positive;
Changes on the defreece side are taken as negative.

Due to the increment of these roll pending forces, the roll gap at the work side plate end position is increased by 2Δyw, and the roll gap at the drive side plate end position is increased by 2ΔyD (
rJ is commonly expressed by the following formula.

Δyw=ΔFw・Δyww+ΔFD・ΔyDw ・・
・(8)ΔyD=ΔFw・ΔywD+ΔFD・ΔyDD
-(9) Therefore, when the plate width of the rolled material is b, and the distance between the rolling support points on the work side and the drive side, that is, the distance between chonks, is t, a difference in elongation rate will occur on both sides of the rolled material due to ΔFW + ΔF'D. In order to avoid this, the work side reduction increment ΔS is
w (the tightening direction is positive) and the drive side reduction increment ΔsD may be controlled.

The α0) formula only shows the relative relationship between 38w and ΔsD, and in order to actually determine ΔsD and 38w, the issue of plate thickness must be taken into consideration.

This should be selected so that the thickness at the edge of the plate, the thickness at the center of the plate, or the average thickness does not change, depending on the operational purpose of controlling the plate thickness at which part of the rolled material. Bye.

As a specific example, in the state shown in Figure 2, ΔF'W = 5
0 ton/chock sΔFD = 50 ton
Consider the case where an increment of /chock is given.

From equations (8) and (9), Δyw=0.5X81+0.
5X(11)=35μmΔyD=0.5X2+0.5X
4=3μm Therefore, roll pending force ΔF'w=ΔFD=5
At the same time as the control of 0 ton/chock, the reduction on the work side may be controlled to be 228 μm smaller than the reduction on the drive side.

For convenience, the above explanation deals with the state in which the rolled material is moved to the work side, but if it is moved to the drive side, the work side and drive side are simply swapped in the previous explanation, and the rest is exactly the same. .

[Brief explanation of drawings]

Figure 1 shows the roll deformation when using the conventional method. When aU increase pending force is applied, b
Figure 2 shows the effect of roll pending force on work roll axis deformation in a four-high rolling mill, where a shows the calculation conditions and b shows the calculation results. It is. 1... Bank up roll, 2... Work roll, 3... Center of plate width of rolled material, 4...
... Mill center, 5 ... Entry side rolled material.

Claims (1)

[Scope of Claims] 1. When rolling is performed with the center of the width of the rolled material intentionally shifted from the mill center to the work side or driver side, and when the roll pending force is corrected according to the rolling state during rolling. , the initial state of the roll pending force on the work side and the drive side is corrected by different values while maintaining a constant ratio that depends on the deviation amount of the mill center force and the rolled material. rolling mill control method. 2. When rolling is performed with the center of the width of the rolled material intentionally shifted from the mill center to the work side or drive side, when modifying the roll pending force according to the rolling condition during rolling, the initial roll pending force The rolling position of the work side and drive side is corrected by different values while maintaining a constant ratio that depends on the amount of deviation of the mill center force of the rolled material. rolling mill control method. 3. During rolling, the roll pending force and rolling position on the work side and drive side are corrected by different values on the work side and drive side while maintaining a constant ratio that depends on the mill center force and deviation amount of the rolled material. A rolling mill control method according to claim 1, characterized in that: