JPS61137658A - Method for estimating thickness of quickly cooled thin strip - Google Patents

Abstract

PURPOSE:To control the thickness of a quickly cooled thin strip in a manner finer than in the conventional practicle by applying the equation between the surface temp. and thickness of the thin strip under the same strip manufacturing conditions made preliminarily with respect to the actually measured value of the surface temp. of the quickly cooled thin strip right after the formation to determine the thickness of the thin strip. CONSTITUTION:A molten metal 3 is supplied from a tundish 1 through a nozzle 2 toward the kiss part of twin rolls 5 and is subjected to the cooling, rolling down and rotation by the rolls 5, by which the thin strip metal 4 is obtd. A scanning type radiation thermometer is attached to a position 9c in this case to measure two-dimensionally the surface temp. of the thin strip under conveyance toward a coiler. The actual thickness of the thin strip is measured by a micrometer after the coiling. The thickness can be estimated within an error of about + or -20mum if the regression line y=1.57X-85 (y; sheet thickness mum, x; surface temp. deg.C) in figure is used as the relation between the surface temp. and sheet thickness obtd. from the above-mentioned experiment. The feedback control of the thickness distribution of the quickly cooled thin strip with extremely less time delay is obtd. by the above-mentioned method and therefore the sheet thickness control in the manner finer than in the conventional practive is made possible.

Description

[Detailed Description of the Invention] (Industrial Application Field) Achieving plate thickness detection, which is one of the important techniques in quenched ribbon production, (1) near the mill and (2) with simple operation. The technical solution described in this specification is to quickly obtain highly accurate thickness information during the process of forming the quenched ribbon.
The purpose of this paper is to propose development results that can be incorporated into the control of the preparation stage.〇Quiet-quenched ribbon can be used for intermediate thickness steel plates such as slabs and hot-rolled plates.
It is a method of immediately producing a thin strip product from molten metal without forming a copper strip, and generally the molten metal is fed from a nozzle toward a (or a pair of) cooling rolls installed near the exit of the nozzle. Even in the case of the rapid cooling method in which a ribbon is obtained all at once by rotation of rolls and cooling (and rolling), it is important that the manufactured ribbon has a predetermined average thickness and that there is little deviation in the longitudinal and width directions. This is an unreliable condition for the product.

However, in the quenching method, there is no multi-roll rolling or reverse rolling as in the rolling method, so once a sheet thickness deviation occurs, it is impossible to correct it in a subsequent process. This is why measurement and control to produce a ribbon with a predetermined thickness and a small deviation in thickness are extremely important in the production of quenched ribbons.

(Prior art) Regarding the thickness measurement of a rapidly cooled ribbon, regardless of whether the single roll method or the twin roll method is used, the gamma ray thickness is measured at a place where the ribbon is sufficiently cooled, as shown in Japanese Patent Application Laid-Open No. 58-28550. This was usually done using a meter such as a meter.

The gamma ray thickness meter is an instrument that has been used in conventional processes for a long time, and there are no particular problems in terms of maintenance or accuracy when using it for the quenched ribbon method.

However, since the measurement location is far from the vicinity of the mill, there was a major drawback in that it could not be used as a control feedback signal due to a significant time delay.

To eliminate time delays, it is necessary to install a gamma-ray thickness gauge near the mill, but this is a place where many of the equipment necessary for manufacturing, such as ribbon guides and splash prevention plates, are already installed. - If a large amount of high-temperature molten metal is scattered, it may lead to a leakage accident of the T-ray source.
It was extremely difficult to install a gamma ray thickness gauge near the mill.

Furthermore, it was impossible to install a plurality of such devices and add a scan mechanism in the width direction of the rim in order to know the thickness distribution in the width direction.

(Problem to be solved by the invention) Measuring plate thickness directly under the mill T#! It took nine months to consider measurement methods other than thickness gauges, but we realized that (1) it can be installed in a limited space directly under the mill, and (2) there is a risk of serious accidents even if molten steel scatters. That there is no.

(8) It is necessary to be able to measure not only the longitudinal direction but also the width direction.The purpose of this invention is to make these wishes a reality.

(Friendly Means for Solving Problems) The present invention is a method for producing a rapidly cooled metal ribbon in which molten metal is supplied to the surface of a rotating cooling roll, rapidly cooled and solidified, and the surface temperature of the ribbon immediately after it is produced is measured.

A quenched ribbon plate characterized in that the ribbon thickness is determined by applying a previously created relational expression between the surface temperature and the ribbon thickness under the same plate-making conditions to the measured value of the surface temperature. This is a thickness estimation method.

Now, we examined the characteristics of the quenching process and found that it was experimentally confirmed that as the ribbon becomes thinner, the cooling effect from both rolls increases, resulting in a lower surface temperature, while on the other hand, as the ribbon becomes thicker, the temperature increases. FIG. 1 conceptually shows the procedure for manufacturing a quenched ribbon using the general twin roll method. The molten metal 8 is supplied from the tundish l through the nozzle 2 to the kissing part of the twin rolls 5, and the molten metal 8 received at the kissing part is cooled, rolled and rotated by the rolls, and immediately becomes the thin metal ribbon 4.

Subsequently, it passes between the guides 60, is placed on the belt conveyor 8 provided under the sill 7 cover and the board cover, and is conveyed to the winding device.

In the case of a gamma-ray thickness meter, it is usually necessary to place the source section and the detection section near this area, surround it with a shielding plate to prevent leakage of r-rays, and add a protective plate to prevent splashing. It is obvious from FIG. 1 that it is impossible to install the gamma ray thickness gauge directly under the mill.

In the figure, 0a-C is an example of a place where a thermometer can be installed, and here the surface temperature of the ribbon can be measured at a few places as shown in the figure, including the width direction of the ribbon. It is clear that the following can be used.

For example, if we use a radiation thermometer that scans a 25° field of view with 3048 COD silicon arrays at a frequency of 80 times per second, in this case, for a ribbon width of 400 mtn,
It is possible to measure the entire width from a distance of about M, and the instantaneous field of view is as small as 2 mu x Z mm.

That is, in the longitudinal direction, it is sufficient to have a clearance of Qm tolerance, and since a separation of 900'rIL'n% can be achieved, there is almost no risk of damage due to tin lash.

As shown in FIG. 1, it is understood that temperature measurements can be made at several locations even in the immediate vicinity of the mill.

(Function) Therefore, the measurement signal of the surface temperature of the ribbon, which is shown as 9a to 9C in Fig. 1 and measured by the thermometer installed at any of the following locations, includes not only the distribution in the longitudinal direction but also the distribution in the width direction. It can be passed to the signal processor 1G. The signal processor 10 calculates the thickness of each point using a separately prepared experimental formula based on the relationship between the surface temperature and ribbon thickness under the same plate-making conditions, and then performs further calculations to calculate the average plate thickness. The thickness and plate crown values can also be calculated. These values can be used as signals for controlling the control device 1IVc feed, plate thickness, and recessed crown.

(Example) In Fig. 1, a scanning radiation thermometer is installed at position 9C,
The surface temperature of the ribbon being conveyed in the direction to the winding machine is
Measured dimensionally. After that winding.

The actual thickness was measured with a micrometer.

This measurement experiment was conducted under exact manufacturing conditions, data was accumulated, and the relationship between thickness and surface temperature was investigated.

The main experimental conditions are as follows.

Plate width: 4ggmm Plate thickness: 800-65 (1m steel type:
5% silicon steel tapping temperature: 1600℃ Roll circumferential speed: 3? FL/S Measurement location: 4m below the roll kiss part Figure 2 shows the thickness change (left vertical axis) and temperature change (right vertical S) in the board width direction. It can be seen that the thickness has also increased. FIG. 8 summarizes the relationship between fc surface temperature and plate thickness obtained during this experiment.

Regression line in the figure y = 1.57 x -850 (y:
Plate thickness μm, x: surface temperature ℃)t? Using this method, it was possible to estimate the plate thickness within an error of about ±20 μm.

Naturally, the regression line will differ if the manufacturing conditions, especially the roll circumferential speed and measurement position, change. Therefore, some experimental formulas that can be used for the manufacturing conditions are determined and the signal processor 1 (
Needless to say, NC input is required.

(Effects of the invention) A feedback control signal for the thickness distribution of the quenched ribbon with very little time delay can be obtained compared to the conventional method.

More fine control of plate thickness is possible.

Thus, according to the present invention, a ribbon with a good cross-sectional shape can be manufactured.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the manufacturing equipment for quenched ribbon, Figure 8 is a chart showing an example of the correlation between thickness distribution and temperature distribution in the width direction of the sheet, and Figure 8 shows the relationship between surface temperature and sheet thickness. This is a diagram. 1... Tandishu 8... Nozzle 8... Molten metal Association... Thin strip metal 5... Roll
6...Kite 7...Suzushushobichi board 8
...Belt conopair 9a-9C...Thermometer
10...Signal processor 11...Control device

Claims (1)

[Claims] 1. Supply molten metal to the surface of a rotating cooling roll and rapidly cool it.
In the manufacturing method of rapidly solidified metal ribbon, the surface temperature of the ribbon immediately after generation is measured, and the actual value of this surface temperature is used to calculate the surface temperature and ribbon thickness under the same plate-making conditions, which have been created in advance. A method for estimating the thickness of a quenched ribbon, characterized by determining the thickness of the ribbon by applying a relational expression between