JPS5938436Y2 - Breakage prediction device for carbon electrode for heating molten steel vacuum degassing container - Google Patents

Description

[Detailed Description of the Invention] The present invention is an apparatus for predicting breakage of a carbon electrode for electrical resistance heating of a vacuum degassing container for molten steel.

Electric resistance heating equipment prevents the molten steel splash generated during the operation of vacuum degassing equipment from adhering to and growing on the refractory bricks in the degassing tank, improving the yield of auxiliary raw materials and extending the life of the refractory bricks. On the other hand, the carbon electrode may break off unexpectedly during operation and be mixed into the processed molten steel, causing the processed molten steel to lose its components and become scrap.

Therefore, there has been a strong desire to detect breakage of carbon electrodes in advance, that is, to develop a breakage prediction device.

Based on the above request, the present inventors first studied the mechanism of breakage of carbon electrodes.

That is, when the electrode is cut, the electrode becomes thin due to oxidative wear and tear due to use, and the mechanical strength of the electrode is thereby reduced.

This decrease in mechanical strength causes cracks in the electrode.
This crack gradually grew larger and eventually broke.

Therefore, in order to know if the electrode is broken, it is sufficient to detect the voltage change at the time of breakage, that is, the arc voltage, which changes rapidly and is easy to understand.

However, the occurrence of this arc voltage is at the time of breakage,
Although it can be detected, the electrode is already broken by the time the arc voltage is detected, so it cannot be used as a predictive signal that will lead to action.

Therefore, the present inventors conducted a more detailed investigation and found that even before the carbon electrode breaks, that is, before and after cracks occur, the voltage supplied to the electrode and/or
Or it turns out that there is a change in the current.

The present invention focuses on the fact that there is a slight change in voltage or current even before the carbon electrode breaks, and monitors this change in voltage or current.The gist of the invention is as follows.

That is, a detector for the voltage or current supplied to the carbon electrode, a filter for extracting the change signal of the detector,
A breakage prediction device for a carbon electrode for electric resistance heating includes a comparator that outputs an output signal when the output signal of the filter exceeds a specified value, and a display and an alarm connected to the comparator.

The present invention will be explained in detail below based on an example shown in the drawings.

Fig. 1 shows the configuration of the device of the present invention in blocks, where 1 is a carbon electrode for electrical resistance heating of vacuum degassing equipment, and 2 is a power supply device (constant current device) that supplies electricity to this electrode. , 3 is a voltage detector that detects the voltage of electricity supplied to the electrode, 4 is a filter that extracts only components that change relatively slowly, such as at 10 Hz or less, 5
is the output signal level of the detector at a specified level, e.g. 2
6 is a counting comparator that outputs when the comparator output signal is inputted at a specified value or more within a specified time; 7 is the output of the counting comparator. An alarm device 8 is a display device.

First, during operation of the vacuum degassing equipment, power is supplied to the carbon electrode 1 using, for example, a constant current device.

In this case, according to the invention, changes in the voltage supplied to the electrode 1 are monitored.

That is, the voltage detector 3 detects the voltage.

The results of monitoring with this voltage detector 3 are shown in FIG.
As shown in FIG. 2A, the voltage changes gradually in a higher direction from a normal state to a breakage point.

Next, the output signal of the filter 4 which extracts only the changing components is as shown in FIG. 2B, which corresponds to FIG. 2A.

If this output signal is small, this signal may be amplified.

In the present invention, since the absolute value of the output signal of the filter 4 is small and easily susceptible to disturbance, the output signal of the filter 4 is changed to this output signal in order to eliminate disturbances and improve prediction accuracy. If the level exceeds a specified level, the output comparator 5 is installed to process the signal.

In this way, only components with a range of change greater than or equal to the specified level (2 volts) become the output signal of the comparator 5.

This is shown in FIG. 2C. Furthermore, in this example, the output signal of the comparator 5 is further processed in order to improve the breakage prediction accuracy.

That is, the output signal is passed through a counting comparator 6 which outputs an output when the output signal is input more than a specified number of times (for example, 7 times/40 seconds) within a specified period of time.

The results are shown in the second figure.

Thus, this result is outputted to the display device 8 and/or the alarm device 7 as a breakage prediction signal.

In the example shown in Fig. 2, the breakage is predicted when the D signal is output, and based on this signal (the output signal of the display device 8 and/or the alarm device γ), for example, the electrode Measures will be taken, such as replacing the

In addition, in FIG. 2, E is a breakage signal that occurs when molten steel processing is continued without replacing the electrode.

In the above explanation, an example was shown in which the breakage of electrode 1 is predicted by detecting voltage changes in the power supply to electrode 1. It is from.

If a constant voltage device is used as the power source, current changes may be detected.

Furthermore, in the case of a constant power device, it may be possible to detect changes in either current or voltage.

In addition, in the above explanation, in order to further improve the breakage prediction accuracy, the component signal from the comparator 5 having a variation range of more than a specified level is further processed by the counting comparator 6 to finally predict breakage. However, although the prediction accuracy is not as high as this,
As long as there is no practical problem, the output signal of the comparator 5 may be used to predict breakage.

As described above, according to the present invention, a change in the voltage or current supplied to the carbon electrode is detected, and breakage is predicted based on the component whose variation range is above a certain level, so breakage can be predicted with high accuracy. This can be predicted and appropriate measures can be taken before electrode breakage occurs.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a device showing an embodiment of the present invention, and FIG. 2 is a time chart showing a breakage prediction state by the device of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Carbon electrode for voltage resistance heating, 2... Power supply equipment for electrical resistance heating, 3... Voltage detector, 4... Filter, 5... Comparator, 6... Counting comparator ,7...
- Alarm device, 8...display device.

Claims (1)

[Scope of utility model registration request] A voltage or current detector supplied to a carbon electrode for heating a molten steel vacuum degassing container, a filter that extracts a change signal from the detector, a comparator that outputs an output signal when the output signal of the filter exceeds a specified value, and this comparator. A device for predicting breakage of a carbon electrode for heating a molten steel vacuum degassing container, consisting of an indicator and an alarm connected to a molten steel vacuum degassing container.