JPS6054137B2 - Method and device for measuring lubrication state between mold and slab in continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a method and device for measuring the lubrication state of a slab continuously drawn from a mold (hereinafter referred to as a mold) in a continuous casting method for molten metal. be.

Generally, continuous casting of molten metal is carried out through a tundish 1 and a mold 2 having a predetermined cross-sectional shape, as shown in FIG.
Molten metal 4 is injected into the mold and continuously drawn out from below as slab 3.

In the process of drawing out the slab 3 from the mold 2, as shown in FIGS. 2 and 3, the mold 2 is vibrated at a constant cycle that matches the operating conditions by a mold vibrating device 100.

From this, the powder 5 on the slab 3 in the mold 2 is melted by the heat of the molten metal 4 and flows between the mold 2 and the slab 3 through mold vibration, acting as a lubricant.
Depending on the lubrication state between the mold 2 and the slab 3, scratches or cracks may occur on the surface of the slab 3, or breakout (hereinafter referred to as I) may occur. However, there is no effective means to measure and evaluate the powder lubrication performance between the mold 2 and the slab 3, or to measure information on the occurrence of surface scratches or how to prevent them, and the deterioration of the lubrication condition is the greatest. The reality is that it is not possible to prevent (1) from occurring when As a method for measuring these lubrication performances, M. L. There is a method based on TektOr (Belgium Patent No. 86903 Crocodile) and a method previously proposed by the inventors that refers to the amplitude ratio or phase difference between vibration input and output. M. L. The TektOr method detects vibrations of the mold 2, sorts the detected vibrations into two frequency ranges, uses one of the vibrations as a reference signal, and determines the lubrication state based on the vibration ratio.

The actual mold vibration device differs depending on the continuous casting equipment, and the mold vibration frequency changes depending on the operating conditions. L. The TektOr method cannot accurately capture changes in the lubrication state between the mold and the slab. The vibration of the drive part of the mold vibration device is input (for example, motor current), and the mold 2
There is a method of measuring the lubrication state by using the vibrations as output and their correlation (amplitude ratio, phase difference).

This method measures both the transmission characteristics of the mold vibration device and the characteristics of the lubrication state between the mold and the slab.
This method has the disadvantage that it cannot measure only the lubrication state between the mold and the slab. It is an object of the present invention to compensate for this drawback and to provide a method and apparatus that also performs equipment diagnosis of the mold vibration device.

In the present invention, the mold vibration device is regarded as a system, and the frequency transfer function of the mold vibration device is determined by vibrating the mold with no load (before casting) in advance.
At least a part of the frequency transfer function is determined online (during casting), and the magnitude and/or phase of the component in a specific frequency region is compared with the results obtained continuously or intermittently. Accurately measure the lubrication state of the mold vibration device, and also evaluate the vibration of the mold vibration device based on changes in the frequency transfer function under no load and the state of change in the frequency transfer function online, as well as perform equipment diagnosis. The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows a mold vibration device 100 for continuous casting equipment, which includes a vibration table 6, a spring 7, an eccentric cam 8,
It is composed of a speed reducer 9 and a motor 10. The mold vibration is generated by vertically vibrating the vibration table 6 in which the rotary motion of the motor 10 is decelerated by the reducer 9 and the rotary motion is converted into vertical motion by the eccentric cam 8 in the reducer 9.

A mold 2 is installed on the vibration table 6. In the present invention, the mold vibration device is considered as one system,
For example, the frequency transfer function is determined using the apparatus configuration shown in FIG. 4, with the motor current or voltage signal as input x(t) and the vibration of mold 2 as output y(t). That is, FIG. 4 shows the configuration of an embodiment of the present invention, in which the input x (
The motor current is detected by the current detector 11 as the vibration input of t), amplified by the amplifier 13, and vibration only in a specific frequency region is determined by the filter 14, and this is detected by the gain/phase meter 1.
7 and is input to the converter 18. The vibration output of the output y(t) is detected by a vibration detector 12 attached to the mold 2, amplified by an amplifier 15, and then filtered to a filter 16 to obtain vibrations only in a specific frequency range and gain this. /Input to phase meter 17. Gain/phase meter 17 has input x(t)
and the amplitude ratio and phase difference of the output y(t) and the signal processing device 1
9 is input. Vibration in a specific frequency range of the vibration input x(t) is input to the converter 18, performs F/V conversion to generate an analog voltage according to the frequency, and outputs an analog output proportional to the frequency to the signal processing device. 19 is entered. Now, the mold frequency is varied while vibrating the mold in a no-load state (when there is no slab 3 in the mold 2).

The amplitude ratio and phase difference between the vibration input x(t), that is, the vibration in a specific frequency range of the motor current, and the vibration in a specific frequency range of the vibration output y(t) of the mold 2 are calculated as gain/phase according to the mold frequency. A total of 17 outputs. The converter 18 outputs an analog output proportional to the frequency. Therefore, the transmission characteristics of the mold vibration device corresponding to the mold vibration frequency under no load (
The gain (amplitude DB) of the frequency transfer function) and the phase difference are:
It is stored in the signal processing device 19 and recorded in the recording/display device 20 at the same time. A summary of the recorded contents is the transfer characteristic shown in FIG. This transfer characteristic is the basis. Next, find the transfer characteristics during casting. Whether or not casting is in progress is determined based on an external signal 22 input to the signal processing device 19. Mold vibration during casting is determined by operating conditions, but the frequency is determined by the transducer 18.
The gain and phase difference with respect to the frequency are stored in the signal processing device 19 because they are constantly measured and input to the signal processing device 19 . The stored contents include the transmission characteristics under no load and the lubrication state between the mold and the slab. Therefore, the difference from the previously stored transmission characteristic under no load indicates the lubrication state between the mold and the slab. No-load transfer characteristics and mold frequency f
The relationship with is expressed by the following equation.

G: gain, φ: phase difference, S, S'': constant In the no-load vibration test, the mold frequency f is variable, G and φ are determined, and the coefficients of equations (1) and (2) are calculated using the least squares method. By finding , it is possible to understand the no-load transfer characteristics.

The mold frequency f is determined as a function of the casting speed Vc.

Generally, Cpm: cycles/min, Y: constant and lowest frequency, and K: constant.

Therefore, if the mold speed is determined, the mold vibration frequency is also determined. With this measurement system, G and φ can be measured in real time.

For example, let G and φ when the vibration pattern frequency is f1 be Gl and φ1. Since f1 is known, the gain and phase difference G at no load are determined by equations (1) and (2).

l, φ01 are found. When the mold vibration frequency f is f1, the difference in transmission characteristics ΔGl and Δφ1 between no load and during casting are as follows.

These ΔG1 and Δφ1 each indicate the magnitude of friction during casting at the frequency f1. The transmission characteristics shown in FIG. 6 indicate the transmission characteristics of mold vibration during casting.

The mark is the gain characteristic, and the mark is the phase characteristic. The arrows ΔG and Δφ shown in the figure indicate the difference in the transmission characteristics with no load, and this difference indicates the lubrication state between the mold and the slab. This difference amount, that is, the difference between the specific value under no load and the characteristic value during casting, is processed by the signal processing device 19 and continuously recorded in the recording and display device 20. Furthermore, the transmission characteristics for casting steel type, casting size, etc. are determined to some extent by operating conditions. These average transmission characteristics depending on the steel type, size, etc. are stored in the signal processing device 19. Therefore, the difference between the transmission characteristics of the currently cast steel type, size, etc. and the averaged transmission characteristics is recorded in the recording alarm display device 21. The difference from the averaged transmission characteristic and the magnitude of the variation become transmission abnormalities, and are used as information for changing operating conditions and equipment maintenance. Furthermore, when determining the transmission characteristics of mold vibration under no load,
The difference with the average transfer characteristic under no load and the difference with the previous transfer characteristic are also recorded in the recording alarm display device 21.

These differences are also utilized for equipment maintenance of the mold vibration device. The signal processing device 19 is connected to a processing computer 23.

Therefore, all the results processed by the signal processing device 19 are transmitted to the computer 23, and the computer 23 calculates the average characteristic value of the transfer characteristic at no load and the average characteristic value of the transmission characteristic during casting by steel type and size. The signal is transmitted to the signal processing device 19. The signal processing device 19 stores these.
Since these data are stored in the computer 23 in chronological order, the operator can always grasp the status of the mold vibration device online using the input/output device of the computer 23, and can manage it while learning. As described above, the present invention provides a method and apparatus that can measure the lubrication state between the mold and the slab and at the same time can be used as equipment diagnostic information regarding the mold vibration device.

The feature of the present invention is that it utilizes the transmission characteristics of the mold vibration device, so (1) the mold and slab are The lubrication state between the two can be measured accurately and in a high range.

(2) W! ．． Since the lubrication state (transmission characteristics) averaged by type and size is compared with the lubrication state (transmission characteristics) during casting to evaluate the lubrication state, it is extremely easy to reflect this in operations.

(3) Actively evaluates the vibration of the mold vibration device based on the differences and changes in the transmission characteristics due to no load over time and the differences and changes in the transmission characteristics due to the same steel type and size during casting, making it extremely easy to maintain equipment. It is valid.

(4) Comprehensively manage the above (1), (2), and (3),
It is extremely effective in detecting surface defects occurring within the mold and predicting breakouts due to differences and changes in the lubrication state and differences and changes in the mold vibration state.

(5) The operator can always grasp and manage the condition of the mold vibration device.

As described above, the present invention considers the mold vibration device as a system, and assumes that the vibration of the drive unit is input X (t) and the vibration of the mold body is output y (t), and that the vibration of the transmission characteristic is changed based on the frequency transmission characteristic. This is a method and device for understanding the lubrication state and mold vibration state depending on the state.

However, the present invention is not limited to digital methods.

FIG. 8 shows an embodiment of the present invention using an analog calculation method. In this, the output y(t) side is a vibration detector 24,
They are a filter 26 and an amplifier 28, and the input x(t) side is a vibration detector 25, a filter 27, and an amplifier 29.
These are input to gain/phase meter 30. The process up to this point is the same as shown in FIG. Amplifier 29 on the input side
The output is input to a gain/phase meter 30 and a function generation setting device 31. The function generation setting device 31 includes an F/■ converter 31-1 that converts the frequency to voltage, and a gain function generator 31-2 that sets the transfer characteristic during no-load and generates a function according to the frequency. It consists of a phase function generator 31-3.
Therefore, Seki. The number generation setting device 31 inputs the no-load transmission characteristic corresponding to the vibration frequency to the arithmetic processing unit 32. Further, the function generation and setting device 31 is configured so that the function characteristics can be set from the outside. The arithmetic processing unit 32 processes the input signal of the gain/phase meter 30 and the input signal of the function generation/setting device 31, calculates the magnitude of the lubrication state between the mold and the slab, and outputs this. As described above, the present invention is not limited to a digital processing method, but may also be an analog method or a combination of digital and analog methods, and is not particularly limited.

Example 1 Figures 5 to 7 show data obtained by implementing the present invention. FIG. 5 shows the frequency transmission characteristics of a mold vibrating device in a continuous slab casting machine at a steelmaking plant under no load. Figure 6 shows the difference between the frequency transmission characteristics measured during casting and the characteristics under no load, and the casting size is 20 x 150.
It is h. FIG. 7 shows the results of continuously recording the difference between the characteristics under no load and the characteristics during casting, that is, the lubrication state. In the figure a-
Between b is normal, and between b and c indicates that the lubrication state has become unstable and surface defects have occurred.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an overview of continuous casting equipment, FIG. 2 is a sectional view showing the state of powder 5 in a mold 2, and FIG. 3 is a block diagram showing the configuration of a mold vibration device.

Claims (1)

[Claims] 1. When continuously casting molten metal while vibrating a mold, the vibration transmission characteristics of the mold vibration system under no load are measured in advance, and the vibration transmission characteristics of the mold vibration system during continuous casting are measured in advance. The lubrication state between the mold and slab in continuous casting, which is characterized by comparing the characteristics and determining changes in the lubrication state between the mold and slab and/or abnormalities in the mold vibration system from the difference in transmission characteristics. How to measure. 2. A detector that detects vibration input in the mold vibration drive device, an amplifier that amplifies the signal from the detector, a filter that outputs vibration in a specific frequency range of the signal from the amplifier, and a vibration that detects the vibration of the mold. a detector, an amplifier that amplifies the signal from the vibration detector, a filter that outputs a vibration signal in a specific frequency range of the signal from the amplifier, and a mold vibration drive device into which the signals from each of the filters are input. A gain/phase meter that outputs the amplitude ratio and phase difference between the vibration input signal and the mold vibration signal, a converter that receives vibrations in a specific frequency range from a filter and outputs a voltage according to the frequency, and a converter that outputs a voltage according to the frequency. Alternatively, it consists of a signal processing device that stores and outputs the gain and phase difference of the transmission characteristics in the vibration transmission system corresponding to the mold vibration frequency under load, and measures the lubrication state between the mold and slab in continuous casting. Device.