JPS6368207A - Sheet width control method for tandem rolling - Google Patents

Abstract

PURPOSE:To prevent sheet width fluctuation and to improve dimensional accuracy by adjusting a roll gap so as to correspond to the inlet side tension of stands thereby eliminating the sheet thickness fluctuation occurring in the load fluctuation generated by the tension control between the stands. CONSTITUTION:The deviation of the width of a metallic strip 2 from the target width and the width fluctuation thereof are measured by an inter-stand width gage 6 and the current of a looper 3 is controlled by an arithmetic controller 7 to control the tension. A roll opening degree controller 8 is operated in accordance with the command of the arithmetic controller 7 to change the tension and to control the same so as not to allow the fluctuation of mass flow at the time of the above-mentioned tension control. The dimensional accuracy of the product is improved by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling strip width in tandem rolling of metal strips.

(Conventional technology and problems to be solved) Strip width control has become one of the important technical issues in order to improve the yield in metal strip processing and meet users' demands for dimensional accuracy. .

From this point of view, the strip width control method using a vertical roll mill has been applied to hot strip mill rough rolling, etc., and has been effective.

However, when it comes to thin strips of gold, the width control method using the vertical roll mill described above is not effective due to problems such as buckling. In tandem rolling of a metal strip, there is a method of controlling the tension applied to the metal strip during rolling by controlling the speed balance of each rolling mill stand and the current of the looper between the stands. For example, JP-A-57-139415
The method disclosed in the publication is a board width control method that utilizes tension control using a louver current.

However, with the strip width control method using tension control as described above, strip width control may become substantially impossible, and there is a problem that strip width control in tandem rolling is not necessarily performed effectively.

It is an object of the present invention to provide a method that eliminates the drawbacks of the above-mentioned conventional techniques and enables strip width control by tension control in tandem rolling with high precision up to an industrially practical level.

(Means for Solving the Problems) In order to achieve the above object, the present inventor attempted various studies and analyzes on the above conventional sheet width control method, and found that in tandem rolling, the rolling conditions of a certain rolling mill stand are Since changes in the rolling mill affect other rolling mill stands via the metal strip being rolled, we have found that there are the following problems.

That is, as shown in Figure 1? In the case of a method of controlling the current of the looper 3 and controlling the tension in a tandem rolling mill having Tα3 to 5 stands, when the tension between the rolling mill stands, which is the purpose of controlling the strip width, is changed, The tension between the downstream rolling mill stands also changes at the same time (see Figure 2), resulting in an unavoidable change in the width of the strip even at locations other than the intended location (see Figure 3). The problem is that it becomes impossible to control the sheet width. In addition, in FIG. 2, the board width was measured by installing board width gauges 4 on the entrance and exit sides of the Nα4 stand, respectively.

The reason for this is considered as follows.

The rolling load in a rolling mill stand where tension may be applied can be expressed by the following equation.

p=p0-(τf+teb)・・・・・・■Here, P
o: Rolling load when iJ force does not act τf: Front tension (output side tension) ′″vb: Backward tension (input side tension) Therefore, the load change due to the change in input side tension is ΔP = -
It can be expressed as Δτb...■.

On the other hand, the plate thickness on the exit side is expressed by the following formula (2), so the change in plate thickness due to load fluctuation is expressed by the following formula (2).

h=s10−・・・・・・■ Here, h: Output side plate thickness P: Rolling load M: Rolling machine mill constant M M Therefore, if the input side tension increases by Δτb, the outlet side plate thickness will increase by Δh. It will become thinner. When the thickness of the plate on the exit side decreases in this way, assuming the rolling speed is constant, the mass flow on the exit side (plate thickness The tension between the stands will increase. Similarly, it is thought that this phenomenon will propagate to downstream stands one after another. When adding 1-1□nm1 huge + τ, the width will be shortened and there will be a risk of falling below the minimum width, which will be a big problem.

Conversely, when the tension on the exit side increases, the rolling load similarly decreases and the mass flow decreases, but as seen from the upstream stand, the flow rate of the material decreases, so the tension between the stands tends to loosen. , the width does not become narrower, and it is unlikely to be a problem.

As mentioned above, in view of these problems in the conventional strip width control method, the present inventor has developed a method for tandem rolling by actively controlling the roll opening degree to keep the mass flow constant during tension control. This makes it possible to control the plate width with high precision through tension control.

That is, the strip width control method using tension control in tandem rolling according to the present invention is to adjust the roll opening corresponding to the entrance tension of the stands to compensate for strip thickness fluctuations caused by load fluctuations caused by tension control between the stands. This feature is characterized in that the plate width is prevented from changing due to the plate thickness variation.

The present invention will be explained in detail below with reference to the drawings.

The principle of plate width control according to the present invention is as follows.

As mentioned above, the variation in plate thickness on the exit side due to the variation in tension on the entry side is It is.

On the other hand, the relationship between the roll opening change amount ΔS and the plate thickness change amount Δh is Δh=□ΔS ・・・・・・■ M+Q Here, Q is the plastic constant of the material, so the output side plate due to the input side tension fluctuation In order to compensate for thickness variations, it is sufficient to change the roll opening degree by M M M .

(Implementation @) Next, an embodiment of the present invention based on the above principle will be described with reference to the drawings.

Figure 4 shows a tandem rolling mill with seven stands 1, a strip width meter 5 is installed on the exit side, and among the loopers 3 installed between the stands, the looper 3 between the Ha 4 and Nα 5 stands is installed. This is the case where ′ is a tension changing looper. FIG. 5 (conventional method) and FIG. 6 (method of the present invention) show changes in the exit side strip width when strip width control is performed by tension control in this tandem rolling mill. In addition, in the figure, (a) is the tension change starting point, T
d is the delay time until the tension change start part reaches the outlet side plate width gauge, (b) is the tension correction point, (c) is) the point at which the part of the metal band that passed through the iα4 stand reached the outlet side plate width gauge, W indicates the target board width.

As can be seen from Figure 5, in the conventional method, as mentioned above,
Because there is tension propagation to the downstream stand.

The plate width starts to become narrower from around point (a), and the plate width has already reached the target plate width W when the tension change start part reaches the exit side plate width meter after the Td waiting time. Undershoot occurs as follows. Therefore, although the tension was immediately corrected at point (b), a narrow portion occurred over area (d).

In contrast, in the method of the present invention, the reduction is corrected so that the mass flow balance of the tandem rolling system is not disrupted due to tension changes between certain rolling mill stands, resulting in substantial undershoot as shown in Figure 6. There is no problem, and appropriate board width control has been achieved.

Figure 7 shows another embodiment of the present invention, in which 1 is a rolling mill stand, 2 is a metal band, 3 is a looper, 6 is a plate width meter between the stands, and 7 is a calculation unit. The control device 8 is a roll opening degree control device (reduction screw, hydraulic pressure reduction device, etc.).

In this board width control method, the gap between the board width of the gold gf2 and the target board width and the board width fluctuation are measured by the inter-stand board width meter 6, and the tension is controlled by controlling the current of the looper 3 by the arithmetic control device 7. At the same time, during the tension control, the roll opening degree control device 8 is operated based on a command from the arithmetic and control device 7, and the mass flow is controlled so as not to fluctuate due to a change in the tension.

Fig. 8 shows another embodiment, in which numeral 9 indicates the width of the entrance plate.

This sheet width control method takes into account the distribution of the total required control amount to a plurality of control ends in order to eliminate large sheet width fluctuations or to make relatively large changes in the target sheet width.

That is, the strip width and strip width fluctuation are measured at the entrance side of the tandem rolling mill using the entrance strip width gauge 9, and the arithmetic and control unit 7 selects the number of control stands and each control oil amount according to the required control amount. decide. The output timing of the control is determined by calculating the part of the metal strip to be controlled from the plate thickness and rolling speed at the exit side of each stand, and tracking the part until it reaches the control stand. In this stand, the tension is controlled by controlling the current of the looper 3 in the same manner as in the previous embodiment, and the roll opening degree control device 8 is operated to prevent mass flow fluctuations by controlling the tension.

In each of the above embodiments, a tandem rolling mill having seven stands was explained, or some of the stands were used as control stands, but it is understood that the total number of stands, the number of control stands, etc. can be changed as appropriate. Needless to say.

(Effects of the Invention) As detailed above, according to the present invention, the problem of strip width control by tension control in tandem rolling is solved by actively adjusting the roll opening, so that the strip width is always Control can be carried out effectively, and precision can be improved to an industrially practical level without the occurrence of particularly narrow portions.

[Brief explanation of drawings]

Figure 1 is! A diagram showing a tandem rolling mill with I03-5 stands, Figure 2 is a diagram showing the relationship between the rear tension increase and front tension change in tandem rolling, and Figure 3 is a diagram showing the relationship between the rear tension increase and width reduction in tandem rolling. Figure 4 is a diagram showing a tandem rolling mill with seven stands, Figures 5 and 6 are diagrams showing changes in strip width in strip width control by tension control, and Figure 5 is a diagram showing a conventional rolling mill. in accordance with the sixth
The figure shows the case according to the method of the present invention, and FIGS. 7 and 8 are diagrams explaining other embodiments of the present invention, respectively. 1... Stand, 2... Metal band, 3... Looper, 4... Plate width meter, 5... Exit side plate width meter, 6... Inter-stand plate width meter, 7... Arithmetic control device, 8... Roll opening degree control device, 9... Inlet side board width gauge. Patent Applicant Kobe Steel Co., Ltd. Patent Attorney Takashi Nakamura Figure 1 #3 $415 Figure 2

Claims (3)

[Claims] (1) In a method of controlling the strip width by controlling the tension between the stands of a tandem rolling mill, the strip thickness variation due to the load variation caused by the tension control between the stands is calculated by rolling the roll corresponding to the entry side tension of the stand. A strip width control method in tandem rolling, characterized in that strip width fluctuations based on strip thickness variations are prevented by removing by adjusting the opening degree. (2) The tension control is performed by installing a board width meter between the stands where tension control is to be performed, detecting the board width, and controlling the tension to correct deviations from the target board width and changes in board width. The method described in Scope 1. (3) The tension control is carried out by installing a plate width meter on the entry side of the upstream stand of the stand where tension control is to be performed to detect the plate width, and until the detection part of the rolled material reaches between the stands. The first aspect of the present invention is to control the tension in order to correct the deviation from the target board width and the fluctuation in the board width, taking into account the time delay of the board width.
The method described in section.