JPS62148061A - Thickness controlling method for rapidly-cooled thin hoop - Google Patents

Abstract

PURPOSE:To measure accurately a contacting length with rolls for a thin hoop and to obtain the thin hoop metal having no deviation of thickness thereof by arranging an ultrasonic detector at a core shaft in hollow part of cooling roll and measuring an intensity of reflection wave caused by oscillating ultrasonic wave toward the roll barrel shell from the detector. CONSTITUTION:The ultrasonic detector 7 arranged on the inner surface of the core shaft 1 in the hollow part of a cooling roll oscillates continuously ultrasonic wave toward a radius direction of the roll barrel shell 2 through cooling water 4 as rotating together integrally with the roll in a body and receives the reflection wave from an inner surface 2a and an outer surface 2b of the barrel shell 2. This receiving wave is transmitted to a pulse receiver 10 through a cable 8 laid and wired in the core shaft 1 and a slip ring 9 set on the core shaft 1. A signal processor 12 receives the reflection wave from the pulser receiver 10 and an angle signal from a rotated angle measuring instrument 11, to calculate a paddle height. In this way, the contacting length of roll for the thin hoop is surely measured and the thickness of thin hoop is effectively controlled by this measuring value.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for controlling the thickness of a quenched ribbon, and in particular, when manufacturing a quenched ribbon using a cooling roll as a cooling body, the invention relates to a method for controlling the thickness of a quenched ribbon. The purpose is to advantageously obtain a ribbon without thickness deviation.

(Conventional technology) The quenched ribbon method is different from the conventional manufacturing method in which intermediate products such as slabs and hot-rolled plates are made and finally finished into ribbons. In particular, typical manufacturing methods include the so-called single-roll method and twin-roll method, in which molten metal is continuously supplied from an injection nozzle to a cooling roll that rotates at high speed, and is rapidly solidified to form a thin strip at once. It is.

Regarding the ribbon obtained by such a quenched ribbon method,
Needless to say, it is an essential condition for the product to have a predetermined thickness in the same longitudinal direction as the thin strip produced by the conventional method.

In the single-roll method and twin-roll method, the thickness is determined by the composition and temperature of the molten metal, the circumferential speed of the roll, and the contact length between the ribbon and the roll. If there is a change in the plate thickness, that change will immediately lead to a change in the plate thickness.

Therefore, measuring the roll contact length is an indispensable technical element in the single-roll method and the twin-roll method, but such measurement has traditionally been considered impossible due to restrictions in terms of the measurement location.

For this reason, the thickness control of the quenched ribbon was developed in Japanese Patent Application Laid-Open No. 58-2355.
As disclosed in Publication No. 0, the thickness of the ribbon is measured using a T-line thickness gauge at a place where the ribbon has been sufficiently cooled to almost room temperature, and the molten metal supply amount or roll circumferential speed is determined based on the measured value. A method of change was adopted.

(Problems to be Solved by the Invention) However, this method has a problem in that since the measurement point is far downstream of the control point, there is a large time lag and a quick response cannot be achieved.

The present invention advantageously solves the above-mentioned problems, and aims to propose a sheet thickness control method that can promptly respond to changes in sheet thickness and quickly restore the thickness.

(Means for Solving the Problems) The inventors focused on the structure of the cooling roll used in the production of quenched ribbons, and investigated the possibility of measuring the contact length from within the cooling roll.

As a result, an ultrasonic probe was installed on the hollow center shaft of the cooling roll, facing the roll shell that forms a water-cooled jacket around the center shaft, and the ultrasonic probe was directed from the probe toward the roll shell. While transmitting a sound wave, the reflected wave of the ultrasonic wave from the outer surface of the roll shell is received, and the time when the intensity of the reflected wave falls below a predetermined value is measured to determine whether the ribbon is in contact with the roll. It was found that the plate thickness can be advantageously controlled by measuring the length and adjusting the molten metal supply amount and roll circumferential speed based on the measured value.

This invention is based on the above knowledge.

In other words, the present invention provides continuous supply of molten metal from an injection nozzle onto a cooling roll rotating at high speed, and when rapidly solidifying the metal to produce a metal ribbon. While transmitting ultrasonic waves from the attached ultrasonic probe in the radial direction toward the roll shell that forms a water-cooled jacket between the outer periphery of the roll shaft and the circumferential surface of the roll shaft, The reflected wave from the outer surface of the shell is received, and the length of the metal ribbon in contact with the cooling roll is measured from the change in the intensity of the reflected wave. This measured value is determined in advance according to the desired plate thickness. This is a method for controlling the thickness of a quenched ribbon, which is characterized in that when the thickness deviates from a set value, the molten metal supply amount and/or the circumferential speed of the rolls are adjusted so as to eliminate the deviation.

Hereinafter, the procedure for controlling the thickness of the quenched ribbon according to the present invention will be explained in detail with reference to FIG.

In Fig. 1, number 1 is the core shaft of the cooling roll used in the twin-roll quenched ribbon method, 2 is the roll shell, and 3 is the cooling water flowing inside the water-cooled jacket formed by the core shaft 1 and the shell 2. 4 is water, molten metal flowing down from a nozzle 5 between cooling rolls, and 6 a thin ribbon produced by solidification of the molten metal. In the figure, 6a is the point where the roll starts contacting the ribbon, 6
b indicates the point where contact ended. Therefore, 6a to 6b correspond to the roll contact length.

Now, 7 is an ultrasonic probe installed on the inner peripheral surface of the mandrel 1 according to the present invention, and this probe 7 is connected to the roll shell 2 via the cooling water 4 while rotating integrally with the roll. Ultrasonic waves are continuously transmitted in the radial direction toward the cylindrical shell 2, and reflected waves from the inner surface 2a and outer surface 2b of the one-word shell 2 are received. This received wave is transmitted to the pulser receiver 1O through a signal cable 8 embedded in the core shaft 1 and a slip linter 9 fitted into the core shaft l.

- The rotational angle position of the Wanbang sonic probe 7 is measured by the rotational angle measuring device 11 attached to the core shaft 1. Further, 12 is a signal processor, which receives the reflected wave signal from the pulsar receiver 10 and the angle signal from the rotation angle measuring device 11, and calculates the paddle height based on the principle described later. do.

[Measurement principle]

Generally, materials I have different elastic waves including ultrasonic waves.

■When waves propagate inside, reflections occur at the boundaries, but
It is known that the magnitude is a function of a physical property value called acoustic impedance of each material, and is expressed by the following equation (1).

Here, R: reflection coefficient zl, 2' Acoustic impedance of the material, 2, that is, the reflection on the surface depends on whether the outer surface 2a of the roll shell facing the probe 7 is in contact with air or a thin strip. The strength of the waves is different. Therefore, if the difference is sufficiently detectable,
With this method, the roll contact length can be measured with high precision.In fact, since the intensity of each of the reflected waves described above varies greatly, the roll contact length can be measured with high precision.

This is proved by the following numerical calculations.

General steel is selected as the quenched ribbon 6, Cu-based alloy is selected as the roll shell 2, and the following impedance values are adopted.

In this case, the reflection coefficient R is: (i) When the roll is in contact with air; (11) When the roll is in contact with the ribbon, that is, when the roll is in contact with the ribbon, air identification is sufficient. It is.

Next, this identification method will be explained in detail with reference to FIG.

(a) shows the reflected wave signal when the roll is in contact with air, and (b) shows the reflected wave signal when the roll is in contact with the ribbon.

In the figure, A is the reflected wave from the probe surface, B is the reflected wave from the roll outer shell inner surface 2a, and [12-1 and 82-2
is the reflected wave from the outer surface 2b. As mentioned above, the height of B2-2 is approximately 1/1O of that of 82-1. Naori 2
The position where it appears is constant regardless of the position of the probe.

Therefore, if you set the gate G so that only the vicinity of 82 is observed, and measure the time when the signal becomes H or less with a pulse counter, the time during which the roll is in contact with the ribbon (1
) can be determined with high accuracy, and the roll contact length can be determined from the relationship between the contact time t and the roll circumferential speed V.

As mentioned above, the thickness of the quenched ribbon strongly depends on the roll contact length, so the set value is determined in advance according to the desired thickness, and the roll contact length measured by the method described above is determined in advance. If the molten metal supply amount and roll circumferential speed are adjusted to eliminate the deviation from this set value, a quenched ribbon having a constant thickness in the longitudinal direction can be obtained.

In addition, in FIG. 1, the ultrasonic probe 7 is mounted on a twin roll.
Although we have explained the case where the probes are installed only on one roll, in order to improve the measurement accuracy of the paddle height, it is possible to install them on the other roll, or to arrange multiple probes side by side in the roll axis direction. It goes without saying that it is effective to measure the paddle height at certain points.

(Example) The experiment was conducted using the apparatus shown in FIG. 1 above.

An ultrasonic probe 7 with a center frequency of IMHz was installed as shown in FIG. The main experimental conditions are as follows.

(1) Roll body shell: Material Cu-Be alloy sleeve thickness 15 mm Outer diameter 400 mmφ Circumferential speed 3 m/s Cooling water amount 20 m3/h (2) Steel type: 5% Silicon steel (3) Roll contact length setting Value: 40n+n+The amount of molten steel supplied was intentionally varied. The relationship between the measured roll contact length and the thickness of the produced ribbon measured with a micrometer is as shown in FIG.

As shown in FIG. 3, the plate thickness and roll contact length have a proportional relationship that is well approximated by a straight line passing through the origin.

Therefore, if the roll contact length is constant, the strip thickness should also be constant.In fact, if the roll contact length is changed by varying the supply amount of molten steel, is it possible to return the supply amount to the original value? , adjust the roll circumferential speed to set the roll contact length to a set value of 40 m.
When the thickness was adjusted to m, a metal ribbon having the desired thickness of 250 μm was stably obtained.

In the above examples, the case where the twin roll method was used as the method for manufacturing the quenched ribbon was mainly explained, but it has been confirmed that similar results can be obtained when the single roll method is used.

(Effects of the Invention) Thus, according to the present invention, when manufacturing a quenched ribbon using a cooling roll, it is possible to accurately measure the contact length of the ribbon roll as a signal for controlling the thickness of the quenched ribbon. Furthermore, since the ribbon thickness can be effectively controlled based on this measured value, it is extremely useful in obtaining a metal ribbon without thickness deviation in the longitudinal direction.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the method for controlling the thickness of the quenched ribbon according to the present invention. Figures 2a and b are diagrams showing the reflected wave signal waveforms from the ultrasonic probe, respectively. Figure 3 is the roll It is a graph showing the relationship between the contact length and the plate thickness of the ribbon.

Claims (1)

[Claims] 1. In producing a metal ribbon by continuously supplying molten metal from its injection nozzle onto a cooling roll rotating at high speed and rapidly solidifying it, the cooling roll is a hollow roll. from an ultrasonic probe attached to the mandrel to the roll body shell forming a water-cooled jacket between the roll mandrel and the mandrel peripheral surface on the outer periphery of the roll mandrel,
While transmitting ultrasonic waves in the radial direction, the reflected waves from the outer surface of the roll shell are received, and the length of the metal ribbon in contact with the cooling roll is measured from the change in the intensity of the reflected waves. A quenched ribbon characterized by adjusting the molten metal supply amount and/or roll circumferential speed to eliminate the deviation when the measured value deviates from a predetermined setting value depending on the desired plate thickness. thickness control method.