JP3150059B2 - Cold rolling method for metal strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a metal strip in a cold rolling mill, and more particularly to a method for accurately predicting a rolling load value when a rolling reduction is low as in a temper rolling mill, and And a method for performing rolling.

[0002]

2. Description of the Related Art In a cold rolling process of a steel strip, a cold-rolled steel sheet finished to a target thickness is generally annealed and then temper-rolled to obtain a predetermined elongation rate to obtain a product. It is a target. The temper rolling mill is computer-controlled so that a target elongation rate is obtained. In this computer control,
It is necessary to estimate the rolling load generated during rolling.

Conventionally, as a model for estimating the rolling load, (2)
The well-known and customary Bland & Ford rolling load equation shown in the equation has been used. _{P b & f = f (k} m, t 1, t 2) Q P L P ...... (3) k m: Mean deformation resistance, Q _P: rolling force function t _1, t _2: inlet side, outlet side unit tension

[0004]

However, in the case of rolling with a small rolling reduction, such as pressure rolling, when rolling is performed using dull rolls, the rolling load is calculated using the rolling load formula of Bland & Ford. When estimated, as shown in FIG. 3, the calculated rolling load tends to be larger than the actual rolling load.
That is, FIG. 3 shows a relational expression between the calculated rolling load calculated by using the rolling load formula of Bland & Ford and the actually required actual value for the rolling load required to obtain a predetermined elongation. However, according to FIG. 3, the calculated rolling load is about 19% larger than the actual rolling load. Also,
The standard deviation σ indicating the accuracy of the relational expression between the actual rolling load and the calculated rolling load is also as large as 13.8%.

This indicates that the use of a mathematical model using the rolling load equation of Bland & Ford gives an elongation ratio greater than the target value and a large variation in the elongation ratio.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for performing cold rolling of a metal strip with high accuracy by using an accurate rolling load estimation formula. And

[0007]

The above object is achieved by cooling a metal strip.
The maximum thickness reduction (ΔT
_WED), The target elongation (r) of the rolled material, the pressure of the rolled material
Thickness (h_i), The rolling load during rolling is
Predicted by equation (1) below, and based on this predicted rolling load,
The problem is solved by controlling the rolling mill and performing rolling. P = P_WED・ Α + P_{b & f}・ (1−α) …… (1) where P_{b & f}Is the rolling load formula of Bland & Ford.
P_WEDIs the rolling load based on the two-dimensional wedge array plane indentation model
It is an expression. Α = 1 (r · h_i<Δ
T_WEDΔT_WED/ (Rh_i) …… (rh_i≧ ΔT_WEDNoto
). Here, the maximum thickness reduction ΔT of wedge pushing
_WEDIs ΔT_WED＝ CR ・ ΔT_B/ R_B…… is given by (2). Here, C is a roll wear correction coefficient. R is
Roll surface roughness, ΔT_BIs the reference thickness reduction, R_BIs the standard
Roll surface roughness.

The inventors have as follows: (a) Plastic elongation in cold rolling is caused by the combined action of the wedge-shaped projections distributed on the roll surface being pushed into the metal strip and the plastic deformation of the metal strip caused by the roll pressure. (b) The plastic elongation generated when the wedge-shaped projection is pushed into the metal band has an upper limit determined by the shape of the wedge. Based on this idea, a new rolling load estimation formula was developed.

The rolling load due to the former action is given by a rolling load equation based on a two-dimensional wedge array plane indentation model.
The rolling load due to the latter action is given by Bland &Ford's rolling load equation.

Formula (1) indicates that when the product of the entry side sheet thickness and the elongation ratio is smaller than the maximum thickness reduction ΔT _{WED of the} wedge pushing, the rolling load equation is governed by the two-dimensional wedge row plane pushing model, When the product of the elongation rate and the product exceeds the maximum thickness reduction ΔT _WED by pushing the wedge, Bl
This shows that the rolling load formula of and & Ford is added.

[0011] (2) roll surface roughness R in formula is the surface roughness before rolling of the roll, the unit may be any one which matches the reference roll surface roughness R _B.

Further, the reference sheet thickness reduction amount ΔT _B is obtained by performing tuning in an actual machine so that the predicted rolling load and the actual rolling load match. That is, in the actual machine, the rolling load calculated only by the two-dimensional wedge row plane indentation model is within the range of r ·
h _i is obtained, and the maximum value is defined as ΔT _WED.
The reference thickness reduction amount ΔT _B is obtained by calculating the equation backward, and is used as a constant thereafter.

Further, as shown in FIG. 2, the roll wear correction coefficient C is a coefficient determined by the total extension (WR pressure extension) of the metal strip rolled by the roll.

[0014]

EXAMPLES The present invention was applied to an actual temper rolling mill to confirm the accuracy of a rolling load estimation formula.

As a two-dimensional wedge array plane indentation model,
The following equation (4) was used.

[0016]

(Equation 1)

In the equation (4), p is the pressing force of one wedge on the steel plate, R _MAX is the wedge height, θ is the wedge apex angle, K ₁ is the number of wedges in the longitudinal direction, K ₂ is the number of wedges in the width direction, and h is the number of wedges in the width direction. average thickness, L _P is the contact arc length, r is an expansion ratio.

Actually, it is determined by the pressing force p of the steel plate of one wedge, the number of wedges in the longitudinal direction K ₁ , the number of wedges in the width direction K ₂ , the wedge height R _MAX , and the wedge apex angle θ in the equation (4).

[0019]

(Equation 2) Are treated as one constant (Dull constant)
The dull constant was determined by performing tuning so that the predicted rolling load matched the actual rolling load in the actual machine.

The contact arc length L _P is L _P = (R ′ · Δh)
^1/2 , (R 'is the flat roll diameter of the hitch cock, and Δh is the thickness reduction). A well-known rolling load formula was used by Bland & Ford.

Further, as a reference roll surface roughness R _B is,
2 μm was used, and 8 μm was used as the reference thickness reduction ΔT _B.

As the roll wear correction coefficient C, the one shown in FIG. 2 was used. The results are shown in FIG. According to FIG. 1, the difference between the actual rolling load and the calculated rolling load is 2% on average.
It is close and the standard deviation is 8%. FIG.
In comparison with, both values are smaller than the conventional method,
It can be seen that the estimation accuracy has been improved.

In the temper rolling using the method of the present invention, the length of the portion where the elongation rate is poor is about 10 m, which is the conventional value.
To less than 5 m.

[0024]

According to the present invention, since the rolling load is estimated by a combination of the rolling load equation based on the two-dimensional wedge row plane indentation model and the rolling load equation of Bland & Ford, the rolling load can be accurately estimated. , Accurate rolling can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a correspondence between a calculated rolling load and an actual rolling load according to the present invention.

FIG. 2 is a diagram showing an example of transition of a roll wear correction coefficient in the present invention.

FIG. 3 is a diagram showing an example of a correspondence between a calculated rolling load and an actual rolling load in a conventional example.

Claims (1)

(57) [Claims] 1. A method for cold rolling a metal strip, comprising:
Indentation maximum thickness reduction (ΔT_WED) And the eyes of the rolled material
Target elongation rate (r), thickness of rolling material entering rolling mill (h_i)
Based on, the rolling load during rolling is predicted by the following equation (1),
The rolling mill is controlled by controlling the rolling mill based on the predicted rolling load.
A cold rolling method for a metal strip. P = P_WED・ Α + P_{b & f}(1−α) (1) where α = 1 (r · h_i<
ΔT_WEDΔT_WED/ (Rh_i) …… (rh_i≧ ΔT_WEDNoto
D) ΔT_WED＝ CR ・ ΔT_B/ R_B…… (2) where P_WEDIs based on the two-dimensional wedge array plane indentation model.
Rolling load, P _{b & f}Is the rolling load of Bland & Ford
Rolling load obtained by the formula, C is a roll wear correction coefficient,
R is the roll surface roughness, ΔT_BIs the reference thickness reduction, R_BIs
This is the reference roll surface roughness.