JPH03138002A - Wet rolling method - Google Patents

Abstract

PURPOSE:To improve the accuracy of a plate thickness as the hardness of a product to be rolled is guaranteed by correcting the gap between rolls so that the deviation between a target plate thickness on the outlet side of a mill and a plate thickness on the outlet side of the mill operated from the plate speeds measured on the outlet side and inlet side of the mill is reduced to zero. CONSTITUTION:A mass flow plate thickness arithmetic unit 17 operates a mass flow plate thickness (h) by an inlet side plate speed Vin obtained by a mill inlet side plate speed indicator 18 and an outlet side plate speed Vout obtained by a mill outlet side plate speed indicator 19 and a plate thickness H' directly in front of the mill estimated from an inlet side plate thickness H measured by a mill inlet side plate thickness meter 12. A plate thickness controller 15 operates a gap transformation S as an outlet side plate thickness deviation to correct the deviation between a target plate thickness ho' on the outlet side of the mill and the mass flow plate thickness (h) and the plate thickness is controlled by a rolling-down controller 16.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for wet temper rolling of thin W4 temporary material.

<Prior art> Conventionally, the hardness of thin steel sheets, especially tinplate sheets, has been generally adjusted by adjusting the components in the steel at the steel manufacturing stage and by adjusting the temperature and time during annealing.
It is not carried out at the i-rolling stage. In other words, conventional skin pass rolling is a complete dry rolling method, and the rolling reduction is kept constant at 1.5% or less, and its role is to eliminate side elongation and ■For degree adjustment and shape correction.

However, recently, with the aim of improving production capacity, simplifying operations, and reducing manufacturing costs, a method has been proposed in which the reduction ratio is changed by wet temper rolling and the hardness is adjusted as a result. ing.

However, in order to adjust the hardness in the above skin pass rolling method, it is very important to control not only the hardness of the mother plate but also the rolling reduction rate of glail rolling. Regular wholesale is being carried out.

As this elongation rate control device, for example, Japanese Patent Application Laid-Open No. 6213
There is a device as described in Japanese Patent No. 209.

This apparatus is shown in FIG. 4, and the tension control system is not shown. In this device, the rotational speed of the pre-dol rolls 2 and 3 installed on the man/outlet side of the mill 1 is sampled by the corresponding pulse oscillator 4.5, and the elongation rate is calculated by the elongation rate calculation device 6.

If a deviation occurs between this calculated value and the target elongation rate ε1, the elongation rate control device 7 controls the rolling down device 8 to change the roll gap and control the shedding rate i11.

Note that 9 is a strip. As shown in 6 and above, the hardness in temper rolling is usually controlled by controlling the elongation rate, and this allows stable production of thin steel sheets of various hardnesses.

<Problem to be solved by the invention> However, in the conventional temper rolling method described above, only the hardness of the quality of the thin steel sheet is guaranteed;
It is not possible to improve plate thickness accuracy. That is, in the portions formed during cold rolling that have poor plate thickness accuracy, there is a problem in that if only the elongation rate control described above is performed, the plate thickness accuracy of the final product will similarly deteriorate, resulting in a significant drop in quality. Although it is possible to improve the accuracy of the plate W by simply controlling the plate thickness, it is impossible to guarantee the hardness.

An object of the present invention is to provide a method for wet temper rolling of thin steel sheets, etc., which can improve the precision of sheet j7 while guaranteeing the hardness of the rolled product.

<Means for Solving the Problems> The present invention aims at determining the permissible upper and lower limits of the rolling reduction from the required hardness control range of the product when performing wet temper rolling in which the hardness of the rolled material is adjusted by changing the rolling reduction. 17. was measured on the input side of the mill so that the rolling reduction rate was within the range of the above-mentioned allowable upper and lower limits. Determine the mill exit side target plate jI from , so that the deviation between the mill exit side target plate thickness and the mill exit side plate thickness calculated from the tentative speeds measured at the mill entry side and the mill exit side is zero, This is a wet temper rolling method characterized by modifying the roll gap.

First, the relationship between the hardness of the product and the rolling reduction in temper rolling is
As shown in the figure. Hardness grade (Tl~T6) on the vertical axis in Figure 2
have a surface hardness (IIR3°A) of about 6. For example, for T2, t-1xz-
t=50 to 56, and as shown in the figure, the range of permissible rolling reduction is about 1 to 4%. However, the range of this reduction rate is
It does not take into account the influence of hardness fluctuations of the base plate and the stricter requirements for surface hardness accuracy.

Therefore, the permissible rolling reduction is in a range smaller than the above range. However, if a high reduction rate is required to increase the surface hardness, work hardening will progress and the change in hardness due to changes in the reduction rate will become smaller, so even if the reduction rate is varied over a fairly wide range, it will not be necessary. It is possible to keep the surface hardness within the range.

As described above, according to Fig. 2, the permissible range of rolling reduction can be determined from the control range of surface hardness by taking into account fluctuations in mother plate hardness. It is possible to control the plate thickness more accurately while keeping it within the control range.

<Example> The control system of the present invention will be explained in detail below.

FIG. 1 is a system diagram showing a specific example of a wet temper rolling mill to which the present invention is applied.

In FIG. 1, 11 is a mill, 12 is a plate thickness gauge, 13 is a reduction rate calculation gamma device, 14 is a target thickness calculation device, 15 is a plate thickness control device, 16 is a reduction control device, and 17 is a mass flow plate thickness. Performance 'J7: 'W position, 18 is Mil's side board shorthand, I9 is Mill exit (!lIl provisional speed R1, 20 is strip.

That is, 1] Eye of the sword (1 vote against r7h.

From this, the rolling reduction rate γ is calculated using the following equation (1).

fl　-h　.

y=xioo(%) ---1-(1
1■! The target plate j7 calculating device 714 calculates that the rolling reduction rate γ calculated for each material to be rolled falls within the above-mentioned allowable rolling reduction range (lower limit value T
l, upper limit γU), the following (a) or (
Calculate the target plate thickness as in b).

(a) When the rolling reduction rate γ is within the allowable rolling reduction range (T!≦
γ≦γU), the target plate thickness 'ho' on the mill outlet side of the plate thickness control device 15 is set to the usual ho.

h o' = h o -----
--(2) (b) If the rolling reduction rate is outside the allowable rolling reduction range (γ<Tp, γ>1 u), the mill outlet target temporary IVho' of the plate thickness control device 15 is set as follows (3). ) or (4) 2.

Note that this change in the target plate thickness on the mill outlet side is carried out at the time when the portion existing at the position of the old plate thickness 12 on the mill inlet side has moved directly below the mill.

In addition, the mass flow plate Pf calculation device 17 calculates the plate speed Vin on the human side obtained from the plate speed meter 18 on the inlet side of the mill, the outlet plate speed VouL obtained from the plate speed 9119 on the outlet side of the mill, and the provisional 17 total 12 on the mill inlet side. Using the plate 1''7-11' immediately before the mill estimated from the measured entrance side plate thickness H, the mass flow (+7h) is calculated by the following equation (5).

h=VouL/Vin*tB---(5
) Note that the method for estimating the plate thickness II' just before the mill from the entrance plate 1rLH is to estimate the thickness II' of the plate immediately before the mill by assuming that the distance between the input plate thickness gauge 12 and the mill 11 is L, and then the part that existed at the position of the input plate thickness gauge 12 is It takes L/Vin seconds to move directly under the mill, so L
This is a method in which the entrance plate thickness I (all determined 1/Vin seconds ago) is set to the current plate thickness H' immediately before the mill.

The plate thickness control device ri'15 controls the target plate thickness h at the mill exit side.
The deviation between o' and the mass flow plate ff, It is calculated as the exit plate rg to be corrected, and the roll gap change reduction ΔS is calculated as the deviation, and the plate thickness control is executed by the rolling down control device 16.

Note that the actuator used for sheet thickness control is not limited to the above-mentioned reduction control device (a tension control device or a roll circumferential speed control device may also be used).

Next, specific examples will be described.

For ultra-low carbon steel with a plate thickness of 0.2 mm and a width of 800 mm,
The method of the present invention, conventional method (I) (elongation control only), conventional method (II) (normal Figure 3 shows a comparison of plate thickness control).

In the conventional method (1), the variation in rolling reduction ratio is 9.5% to 10.
It is within the range of 5%, which is good, but Kari 17 is affected by the mother plate and has large fluctuations, up to 4μm (2
, 5%) occurs. In addition, the conventional method (II
), plate thickness control is implemented, so the plate thickness variation is ±
Although the rolling reduction rate is within the range of 2 μm (±1%), the rolling reduction rate fluctuates greatly, and there are parts where the rolling reduction rate exceeds the allowable rolling reduction range.

On the other hand, in the method of the present invention, the thickness is completely controlled in areas where the variation in thickness of the base plate is small, so ±2μ111 (±1
%) is within the range. In addition, in the method of the present invention, even in areas where the thickness variation is large, the exit side plate thickness variation (2) can be made smaller compared to the conventional method.

On the contrary, although the rolling reduction rate fluctuates more than in the conventional method (1), it does not exceed the permissible rolling reduction rate as in the conventional method (II), and the hardness can be rolled within the standard range.

<Effects of the Invention> As described above, according to the wet temper rolling mill method of the present invention, it is possible to improve the plate r precision while guaranteeing the hardness of a rolled product such as a thin steel plate.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a specific example of a wet temper rolling mill to which the present invention is applied, and Fig. 2 shows the reduction ratio and surface hardness H, during temper rolling. Figure 3 is a diagram showing the results of temper rolling for the conventional method (+), ([1) and the method of the present invention. It is a system diagram showing an elongation rate control system. 11... Mil, 12... Plate thickness meter, 13... Rolling reduction calculation device, 14... Target plate thickness calculation device, 15... Board Thickness control device, 16... Rolling down control device, 17... Mass flow plate thickness control device, 18... Mill inlet side plate speed meter, 19... Mill outlet side plate speed old, 20... Slippery Nbu.

Claims (1)

[Claims] When performing wet conditioning rolling, which adjusts the hardness of the rolled material by changing the rolling reduction ratio, the permissible upper and lower limits of the rolling reduction ratio are determined from the required hardness control range of the product, and the rolling is carried out within the range of the above-mentioned permissible upper and lower limits. In order to maintain the same ratio, the mill outlet target plate thickness is determined from the plate thickness measured at the mill inlet side, and the mill outlet calculated from the mill outlet target plate thickness and the plate speed measured at the mill inlet and outlet sides. A wet temper rolling method characterized by modifying the roll gap so that the deviation from the side plate thickness is zero.