JPH0437406A - Control method of edge drop of plate in tandem rolling - Google Patents

Abstract

PURPOSE:To set a shift position without generating unstable phenomenon by calculating from the sheet crown of that stand and the shift position of each of forward stands in the case of setting the shift position of a certain rolling stand of plural rolling mills in a tandem mill. CONSTITUTION:In the case work roll of which the one end of roll barrel is tapered is provided in plural rolling stands and the shift position of a certain rolling stand of the tandem mill with which rolling is executed by shifting the work roll in the width direction is set, the control point of edge drop to that rolling stand is provided and the shift position of work roll of that rolling stand is calculated from the sheet crown at the control point of that rolling stand and the shift position of work roll of each of forward rolling stands or from rolling condition, quality condition, etc., in addition to them.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a tandem rolling mill in which a plurality of rolling stands are arranged in parallel, and a work roll shift device is installed in the plurality of stands to control edge drop. The present invention relates to a method for determining a work roll shift amount.

(Prior Art) Having a rolled plate profile or rectangular cross section is an important quality factor for rolled products, and the demand for this has been increasing in recent years.

In order to manufacture products with a rectangular cross section, it is necessary to reduce the edge drop near the edge of the plate that occurs during the rolling process. A method of shifting the work roll in the sheet width direction is disclosed, for example, in Japanese Patent Publication No. 60-51921.

The edge drop reduction effect of Work Role Shift is more effective when used simultaneously on multiple stands than when used on a single stand alone.

On the other hand, when work roll shifting is performed using a plurality of stands, the problem is how to appropriately determine the shift position, but this method has not yet been established.

For example, if there is a difference between the edge drop (predicted value or measured value) of a rolled plate and the target edge drop, the work roll shift position of the No. 1 stand is determined so that the difference is resolved on the No. 1 stand, and the If the difference is not completely resolved by only using stand No. 2, a method may be considered in which the remainder is determined sequentially, such as from stand No. 2 onwards. However, according to such a method, the work roll shift of the subsequent stand may not necessarily be effectively utilized, and the effect of having work roll shift in a plurality of stands is reduced.

(Problems to be Solved by the Invention) Edge drops in plate rolling are usually limited to the edge of the plate width, and for example, in cold rolling, they occur within a range of about 100 degrees inside the edge of the plate. This area needs to be controlled in order to obtain a rectangular cross section. However, it is quite difficult to control this entire area with one stand. In other words, the edge drop improvement effect of tapered work rolls has a pattern in the strip width direction in one stand, but that pattern does not necessarily match the edge drop of the strip on the entry side of the rolling stand, and As a result, in certain parts of the plate width direction, the plate thickness becomes larger than the surrounding area, resulting in a protrusion (build-up), or conversely, the edge drop improvement effect is too small.

By understanding this phenomenon in actual rolling and further considering it, the inventors of the present invention have found that the effect of improving edge drop is generally exerted to the inner side in the width direction of the sheet within the area where it is possible to roll the earlier the stand is. We obtained the knowledge that it is possible.

Based on this knowledge, the present invention is based on improving the inner part in the board width direction in the front stage stand, and improving the outer part in the board width direction in the rear stage stand. It is an object of the present invention to provide a control method for rolling a steel plate having a cross section closer to a rectangle in principle by adjusting the positions of the tapered work rolls of the plurality of stands described above.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following points. That is, (1) in a tandem rolling mill in which work rolls with one end of the roll barrel tapering are installed in a plurality of rolling stands and the work rolls are shifted in the width direction for rolling, a certain rolling stand shift position is used. When setting an edge drop control point (position in the strip width direction) for the rolling stand, the edge drop control point (position in the strip width direction) is set, and the edge drop control point is set from the original sheet crown at the control point of the rolling stand and the work roll shift position of each rolling stand in front, or in addition to these. A method for controlling the edge drop of a plate in a tandem rolling mill, characterized in that the work roll shift position of the rolling stand is calculated from rolling conditions, material conditions, etc.

(2) The rolling mill according to the preceding paragraph, characterized in that when calculating the work roll positions of the plurality of stands, the edge drop control point in the previous stage stand is placed inside in the strip width direction from the edge drop control point in the subsequent stage stand. Edge drop control method for plates.

It is.

The present invention will be explained in detail below.

FIG. 1 shows an embodiment of the plate edge drop control system in a cold rolling mill of the present invention, in which NQ, 1 to Nci,
5 is applied to a tandem rolling mill consisting of a five-tier stand (only work rolls are shown in the figure). 2 in the figure is a plate crown measuring device on the entry side of the rolling mill 1, and the rolling mill S
Measure the crown shape in the width direction. 3 is a crown 11PI gauge for the rolled plate provided on the exit side of the rolling mill. Step 4 involves inputting the material properties, rolling conditions, crown of the original sheet immediately before each stand, etc. for each coil, adjusting the parameters in the theoretical model in advance, and using a calculation model that approximates actual rolling to calculate the edge for each stand. This is an arithmetic control unit that sets a drop control point and determines the shift position of the work roll so that this point becomes a target value.

5 inputs a signal from the inlet side crown measuring device 2 or inputs a signal obtained by measuring the edge drop amount of the rolled plate based on a signal from the outlet side rolled plate crown measuring device 3, and performs the arithmetic control. The work roll position control section compares the work roll shift amount target value for each stand determined by the work roll position control section and controls the shift amount to stop.

In the control system, an example of calculation control of the present invention will be described below.

Figure 2 shows an example of calculation based on the theoretical model published by Matsumoto et al. in [Plasticity and Processing J VOL 23° No. 283. This calculation was performed by the inventors after adjusting the parameters in the theoretical model to approximate the results of actual rolling experiments.

Figure 2 shows the case where work rolls with tapered ends (tapered by 120 μm per 100 m) are shifted to stands 1 to 4 in a 5-stand cold rolling mill. The side plate thickness is 2.3mm.

As shown in Figure 2, if we ignore small differences, the position 30mm from the plate edge is not affected by the work roll position from stand No. 2 onwards, and similarly, the position 25mm from the stand No. 3 is unaffected by the position of the work roll after stand No. 3.
It can be seen that the 0 mm position is not affected by the work roll position after the 4th stand.

Therefore, for example, expression using the following arithmetic expression is possible.

CM 30-a, -HOT3. +b,,・HCW, +cM25- a2+' HOT25+b21” HCWI +b22
・HCW2+c2 M2o- a3.・HOT2o+b3.・HCW +b32 SoH
CW2 +b3pi HCW3 +CC51C,, - a41 e ao"r,, + b41 e acwl
+b42 dispute HCW 2 +b 43 ・HCW 3 +
b 44 ”HCW4 + C4 to 2 CM, is the exit edge drop amount at the point X from the sheet edge (edge drop amount after cold rolling) HOT, is the incoming edge drop ji at the point X111 from the sheet edge (cold rolled edge drop amount) Front edge drop amount) HCW is the work roll tapering start point of stand No. 1 alL blj + cil is a coefficient.

Expression using such an arithmetic expression produces the following result in terms of control.

(i) HCW can be determined from CM io, HOT 30. That is, although the control is for multiple stands, the calculation structure is very simple.

(it) HCW2 is CM 25. HOT 25. H
It can be determined from CW +. Since HCW is determined by (i), this means that HCW2 is CM2. .

HOT 2 , which means that it can be determined substantially from HOT 2 .

The same applies to the stands after (Ni).

The effects of this are as follows: (1) The calculation structure is simple, so the calculation time for setting is short and adjustment is easy.

When used for control such as feedback or feedforward, it has the same effect, and avoids the destabilization phenomenon caused by mutual interference in the first stage of control, which is a common problem in control when multiple control means are used. I can do it.

(2) Based on the rolling phenomenon for the formation of edge drops, there are a plurality of control points in the width direction of the sheet, and since these can be controlled independently, a rolled sheet with a rectangular cross section can be easily obtained.

It should be noted that the equations and positions in the plate width direction used in the above explanation are just one example, and even if the molding or the like is changed, the contents of the present invention will not be affected. For example, (1) in the above embodiment, the forming is linearized with emphasis on simplicity of calculation, but it may also be a quadratic equation, which would improve the edge drop prediction accuracy. . The reason why the factors constituting the equation (2) are narrowed down to CM, HOT, HCW+, etc. is based on the same reason, and if the rolling load Pl etc. are further added, the prediction accuracy will be further improved. (3) Board width direction position 3
0mm, 25mm, 20+am, 15mm, etc. should be changed depending on the hardness of the material to be rolled (the range from the plate edge where each stand has an edge drop correction effect changes depending on the hardness) and the area where rectangular cross section is particularly important. It is something.

Taking the above factors into consideration, the structure of the calculation according to the above explanation can be generally illustrated as shown in FIG. 3.

As can be easily concluded from the above explanation, the front stand has a lower control point (width direction position:
The value of X in FIG. 2) should be located at position j in the board width direction.

(Effects of the Invention) As explained above, the present invention allows edge drop control points to be set at different positions in multiple stands of a tandem rolling mill, thereby simplifying setting and control without causing instability. It can be done by calculation,
Furthermore, as a result of controlling a plurality of parts of the rolled plate, a product plate with a rectangular cross section can be easily obtained, which greatly contributes to improving the rolling yield.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the overall configuration when the method of the present invention is applied to a cold rolling mill. FIG. 2 is a diagram illustrating the relationship between the amount of change in edge drop and the position of the tapering start point of the work roll end of each stand. FIG. 3 is a diagram illustrating a method for determining the location of the start point of the work roll end taper based on the method of the present invention.

Claims (2)

[Claims] (1) A certain rolling stand shift position is set in a tandem rolling mill in which work rolls with one end of the roll barrel tapering are installed in multiple rolling stands, and the work rolls are shifted in the width direction of the strip for rolling. In this case, an edge drop control point (position in the sheet width direction) is provided for the rolling stand, and the work roll shift position of the original sheet crown at the control point of the rolling stand and each rolling stand in front or in addition to these is provided. A method for controlling the edge drop of a plate in a tandem rolling mill, characterized in that the work roll shift position of the rolling stand is calculated from rolling conditions, material conditions, etc. (2) When calculating the work roll positions of the plurality of stands, the edge drop control point in the previous stage stand is placed inside the edge drop control point in the board width direction from the subsequent stage stand. A method for controlling plate edge drop in a rolling mill.