JPH0372921B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a melting position measuring device for measuring the distance and center position between materials to be melted, such as steel, placed oppositely to be arc melted.

[Technical background of the invention]

For melting steel, alloys, etc., there is a technique called arc melting, which generates an arc and uses the heat of the arc to melt the material. Among these technologies, VADER (Vacuum Arc Double
There is something called the Electrode Remelting method. As shown in Fig. 9, a pair of consumable electrodes 2 and 3 are installed horizontally opposite each other on the upper part of a non-water-cooled mold 1, and an arc A is placed between these electrodes 2 and 3 in a vacuum.
is generated, and the electrodes 2 and 3 are melted by this arc heat.

Furthermore, there is also a technique shown in FIG. 10 as another melting method. That is, the consumable electrodes 4 and 5 are placed horizontally or downwardly facing each other on the upper part of the mold 6 so that their center lines intersect, and the consumable electrodes 4 and 5 are placed between each electrode 4 and 5 and between each electrode 4 under vacuum or in an inert gas atmosphere. , 5 and the mold 6 and remelting ingot 7, and the electrodes 4 and 5 are melted by the arc heat.

The consumable electrodes 4 and 5 are configured to be able to slide in the longitudinal directions A and B and also to be movable in the C and D directions. The gap between 4 and 5 has been adjusted. The molten metal thus melted falls and enters the mold 6, where it forms a molten pool 8 and solidifies to produce an ingot 7.

By the way, in the above-mentioned arc thermal melting technology, in order to stably generate an arc, melt efficiently, and produce high-quality and uniform ingots, it is necessary to adjust the spacing between each electrode 2, 3 and 4, 5, It is important to know information about the center location of the vehicle. That is, if the interval is long, no arc will be generated, and if the interval is short and the electrodes are in contact with each other, no arc will be generated and it will be difficult to re-ignite. In addition, when manufacturing ingots and hollow pieces with small cross-sectional areas, it is necessary to drop molten metal in the form of droplets to a predetermined position within the mold, so the spacing between the electrodes and their center position must be controlled with high precision. Must be.

[Problems with background technology]

However, conventionally, information on the spacing between each electrode and the center position is obtained through visual inspection by an operator, and the spacing between the electrodes and the center position are controlled based on this information. Therefore, it is difficult to obtain an appropriate electrode spacing and center position for arc generation, and there is a need for a control device for this purpose.

[Purpose of the invention]

The present invention was made based on the above circumstances, and
The purpose is to provide a dissolution position measuring device that can measure the electrode spacing and its center position online.

[Summary of the invention]

The present invention detects the brightness of a material to be melted facing each other by a brightness detector equipped with an optical filter that removes an arc light component and passes a radiance component, and uses this detection signal to determine the temperature distribution of the material to be melted. This is a melting position measuring device in which the interval position calculation means determines the interval and center position of the material to be melted from this temperature distribution.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of the dissolution position measuring device. In the figure, 10 is a vacuum vessel of a melting furnace, and 11 and 12 are electrodes as materials to be melted. C is an arc, and 13 is falling molten metal in the form of droplets.

20 is an imaging device as a brightness detector,
This detects the radiance distribution of the electrodes 11 and 12 through a measurement window provided in the vacuum container 10, and the field of view 5 is one-dimensional so that each electrode 11 and 12 can fit therein.

30 is an arc position calculating device which receives a video signal from the imaging device 20, calculates the temperature distribution of each electrode 11, 12 from this video signal, and calculates the electrode spacing and its center position from this temperature distribution. It is something to seek.

Here, the specific configurations of the imaging device 20 and the arc position calculation device 30 will be described with reference to FIG. 2.

The imaging device 20 has an optical filter 21 at its tip.
is provided, and the brightness light that has passed through this optical filter 21 passes through a lens 22 and is imaged onto a sensor 23. This center 23 has a structure in which a large number of photoelectric conversion elements are arranged in one dimension. For example, it has a structure in which 1024 silicon photo diode arrays (linear array, CCD one-dimensional center) are arranged as photoelectric conversion elements. There is.

Here, the optical filter 21 will be explained.
FIG. 3 shows a relative comparison between the spectral radiation characteristics of the arc C generated between the electrodes 11 and 12 and the spectral radiation characteristics of a blackbody obtained using a blackbody furnace. In addition,
In the figure, the arc spectrum is one example of several types of materials to be melted, but the spectrum will differ even if other materials are used, or if the inert atmosphere or degree of vacuum is changed. It has been found that radiation above 0.85 μm can be almost ignored compared to blackbody radiation. The figure also shows a multi-channel detector using a silicon photodiode array as a detector.
Measurements were made using a channel spectrometer, and it was found that the overall spectral sensitivity of the lens, diffraction grating, and photo diode array used was as shown in FIG.

As shown in Figure 3, the radiation spectral characteristics of arc light have a strong spectrum up to a wavelength of around 0.80 μm. On the other hand, it can be seen that at wavelengths of 0.80 μm or less, the spectrum of arc light using a silicon photodiode array is very weak and almost negligible compared to, for example, blackbody radiation at 1500°C P1 and 1650°C P2.

Therefore, the optical filter 21 in this embodiment
In order to improve the S/N ratio, an infrared transmission filter with a wavelength of 0.90 μm or more is used to remove arc light, and the radiance distribution of each electrode 11, 12 is detected. In this case, as shown in Figure 4, even at wavelengths of 0.90 μm or more, silicon photo
The diode array has sensitivity and can provide a sufficient output value even when the temperature to be measured is 1400°C or higher.

Further, the lens 22 is provided with a focal length selected such that the field of view is the movement range of each electrode 11, 12. Further, the imaging device 20 includes a driver circuit 24 for driving the center 23 and a video signal amplification circuit 25.

Next, the configuration of the arc position calculation device 30 will be explained. The start pulse generation circuit 31 generates a start pulse to start the driver circuit 24, and the frequency of this start pulse (center 23
When measuring an object of constant brightness, the scanning frequency (scanning frequency in 32 determines the level of the video signal from the video signal amplification circuit 25 to determine whether it has reached near the melting temperature, sends this to the sequence control section 33, and sends the video signal to the radiance distribution storage section 34. It is something to do. Note that the video signal is stored in the radiance distribution storage section 34.
Increasingly, information is digitized before it is stored in the computer. Reference numeral 35 denotes an interval position calculation unit which reads out the digital video signal stored in the radiance distribution storage unit 34 to determine the temperature distribution of the electrodes 11 and 12, and calculates the temperature distribution of each electrode 11 and 1 in this temperature distribution.
2, and converts these peak level positions into the position of the photoelectric conversion element at the center 23 to determine the spacing between the electrodes 11 and 12 and the center position thereof. The initial value setting section 36 includes the electrodes 11 and 12 before the start of arc melting.
Information on the intervals and center positions thereof are set in advance.

Next, the operation of the apparatus configured as described above will be explained. Electric current is supplied to each electrode 11, 12 to generate an arc C, and when the arc heat reaches the melting temperature, each electrode 11, 12 melts and drops into the mold as molten metal 13 in the form of droplets. .

On the other hand, when a start pulse is sent from the start pulse generation circuit 31 to the driver circuit 24 according to a command from the sequence control section 33, each photoelectric conversion element (silicon photo diode,
array) is driven and scanned. By the way, imaging device 2
0 is installed so that its field of view 5 can supplement each electrode 11, 12, so the image of each electrode 11, 12 is formed on a sensor 23 through an optical filter 21 and a lens 22. Here, the optical filter 21
Since an infrared transmission filter is used, the arc light is removed and only the radiance components of each electrode 11 and 12 reach the sensor 23. This allows sensor 2
3, the video signal corresponding to the radiance distribution passes through the video signal amplification circuit 25 to the scanning frequency determination section 3.
Sent to 2. The scanning frequency determination unit 32 determines whether the level of the input video signal has been reached to determine whether the melting temperature has been reached, and if the melting temperature has been reached, it sends a message to that effect to the sequence control unit 33. here,
If the melting temperature has not been reached, the sequence control unit 3
In response to the command No. 3, information on the interval and center position before the start of arc melting is read from the initial value setting section 36, and the position of each electrode 11, 12 is controlled based on this information.

Now, when the melting temperature is reached, the video signal is converted into a digital video signal through the scanning frequency determination section 32 and stored in the radiance distribution storage section 34. Therefore, the interval position calculation section 35 uses this storage section 3.
The digital video signal stored in 4 is read out, and the distance between each electrode 11, 12 and its center position are calculated and determined. That is, the temperature distribution of each electrode 11, 12 is determined from the digital video signal. Here, assuming that the temperature distribution is as shown in FIG. 5, the peak level V _nax (V _a ) corresponds to the tip of the electrode 11, and the peak level V _nax (V _b ) corresponds to the tip of the electrode 12. . Furthermore, this peak level
V _a and V _b correspond to the highest temperature portions of each electrode 11 and 12. Therefore, the positions of these peak levels V _a and V _b are converted into the element positions of each silicon photo diode array of the sensor 23. This conversion process will be explained with reference to FIG. 6. _{V nax ・ α} (0<
A threshold value of α<1) is set, and elements n _a satisfying the formula are sequentially searched for from the first element.

V _(oa) >αV _a >V _(oa+1) (1) Next, a search is performed sequentially toward the n (1024)th element to detect an element n _b that satisfies the following equation.

V _(ob) <αV _b <V _(ob+1) ...(2) From the element positions n a and n _b corresponding to the tips of each electrode 11 and 12 obtained in this way, each electrode 1 _is
The interval of 1,12 is found. That is, the interval
Nc is obtained by calculating Nc=n _b −n _a (3).

Next, the center position n _c between the electrodes 11 and 12 is determined by performing the calculation n _c =( _na + n _b )/2 (4). In addition, the interval Nc obtained as above and its center position n _c
The center position corresponding to each element position of the sensor 23 is determined. Information on the distance and center position thus determined is sent to an electrode position control section that controls the amount of current supplied to each electrode 11, 12 and the position of each electrode 11, 12, for example. Note that FIG. 7 shows a configuration in which electrode position control sections 40 and 41 are added.

As described above, in the above embodiment, upon receiving a video signal from the imaging device 20 provided with an infrared transmission filter, the arc position calculation device 30 calculates the temperature distribution of each electrode 11, 12 from the video signal,
Based on the peak level of the level in this temperature distribution, the tip position of each electrode 11, 12, which is the highest temperature part, is determined, and the electrode spacing and its center position are determined from this tip position. The tip positions and center positions of the electrodes 11 and 12 can be accurately measured, and the spacing and position of each electrode 11 and 12 can be controlled based on this information. Therefore, the arc C can be generated stably, melting can be carried out efficiently, and high quality and uniform ingots can always be produced. Moreover, since the falling position of the molten metal in the form of droplets can be accurately controlled, ingots, hollow pieces, etc. with small cross-sectional areas can also be produced uniformly and with high quality.

Note that the present invention is not limited to the above embodiment. For example, as shown in FIG.
0 is a two-dimensional image capturing device (silicon, vidicon,
Alternatively, the spacing and center position may be determined by determining the temperature distribution of each electrode using a center position calculating device 51 using a two-dimensional solid-state imaging device (such as a two-dimensional solid-state imaging device). Further, it may be applied to an arc melting device using the VADER method.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a dissolution position measuring device that can measure the electrode spacing and its center position online.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the dissolution position measuring device according to the present invention, Fig. 2 is a specific block diagram of the device of the present invention, and Fig. 3 is a relative diagram of the spectral radiation characteristics of an arc and a black body. Figure 4 shows the spectral sensitivity of the multi-channel spectrometer, Figure 5 shows the temperature distribution measurement results using the device of the present invention, and Figure 6 shows the calculation of the spacing and center position of the device of the present invention. FIGS. 7 and 8 are schematic diagrams for explaining the operation, and FIGS. 9 and 1 are diagrams showing modified examples of the device of the present invention.
Figure 0 is a configuration diagram of an apparatus using the arc melting method. 10... Vacuum container, 11, 12... Electrode, 20
...Imaging device, 21...Optical filter, 22...
Lens, 23... Sensor, 30... Arc position calculation device, 32... Scanning frequency determination section, 34... Radiance distribution storage section, 35... Interval position calculation section, 3
6...Initial value setting section.

Claims (1)

[Scope of Claims] 1. An apparatus for generating an arc and melting materials to be melted that are placed opposite each other using the heat of the arc, wherein a plurality of photoelectric conversion elements are arranged to detect the brightness at each tip of each of the materials to be melted. a brightness detector; an infrared transmission filter provided in the brightness detector to remove arc light components; Temperature calculating means for calculating the temperature distribution at the tip of the melted material, and comparing the voltage corresponding to each temperature of the temperature distribution calculated by this temperature calculating means with a reference value determined based on the peak level of this voltage, The distance determined by determining the photoelectric conversion elements located at positions corresponding to the tip portions of each material to be melted, and calculating the spacing and center position of the tip portions of the material to be melted based on the positions of these photoelectric conversion elements. 1. A dissolution position measuring device comprising: position calculation means. 2. The dissolution position measuring device according to claim 1, wherein the infrared transmission filter transmits light having a wavelength of 0.90 μm or more. 3. The spacing position calculation means calculates the spacing Nc between the tip parts of each material to be melted and the center position nc, when the positions of the photoelectric conversion elements located at the positions corresponding to the tip parts of each material to be melted are respectively na and nb. The dissolution position measuring device according to claim 1, wherein Nc=nb-na nc=(na+nb)/2 is calculated.