JPS6143696B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for photographing welding arc phenomena.

Photographing, recording, and analyzing welding arc phenomena are extremely important for research on improving welding rods and welding methods. However, the welding arc phenomenon is irregular and fluctuates rapidly, and because it emits strong light, it cannot be clearly observed with the naked eye, and is generally observed by photographing it with a high-speed camera.

This method of using a high-speed camera makes it possible to capture sudden arc phenomena, but the amount of light generated from the welding arc also fluctuates rapidly and irregularly, making it impossible to always take pictures under optimal exposure conditions. Therefore, there are many places where only the intense arc light appears white, and places where almost nothing is shown due to underexposure, making it difficult to observe the phenomenon accurately. In particular, it is difficult to photograph a phenomenon in which short circuits and arcs occur repeatedly, such as the short circuit transfer phenomenon in carbon dioxide arc welding, because it is similar to the repeated flashing and extinguishing of intense light.

In view of the above, it is an object of the present invention to provide a welding arc phenomenon photographing device that can sufficiently clearly photograph even a phenomenon that is extremely difficult to photograph, such as a short-circuit transition phenomenon.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In FIG. 1, 1 is a DC power supply (hereinafter referred to as a power supply), and this power supply 1 provides a DC voltage. 2 is a DC reactor, and a welding arc 3 is obtained by a circuit constituted by a power source 1 and this DC reactor 2. The magnitude of the current of this welding arc 3 is detected by a current detector 4 and inputted to a control device 5. Control device 5 converts this current signal into a voltage level at which electro-optic ceramics 6 can operate. This electro-optical ceramic 6 can arbitrarily control the amount of transmitted light by adjusting the magnitude of the welding current, and is, for example, a PbLaO ₃ solid ceramic.

When photographing a welding arc phenomenon using the apparatus configured as described above, when the welding current increases due to a short circuit of droplets as shown in the oscillograph of FIG. When the current increases to a preset current level 1a or higher, an operating voltage Va is applied to the electro-optic ceramics 6. Electro-optic ceramics 6
When the operating voltage Va is applied to the device, its light shielding ratio changes and becomes about 1/30 or less of the value before application. In other words, the aperture is fully opened. When the droplets are short-circuited, the welding arc is extinguished, so naturally the amount of light incident on the film (light-receiving surface) is less than 1/30 of that when the welding arc is occurring.

Therefore, as shown in Figure 2, when a welding arc is occurring, the voltage applied to the electro-optic ceramics should be set to zero or minus several tens of volts.
By applying several hundred volts when the welding arc is extinguished, the amount of light incident on the film can be kept almost constant.

FIG. 3 is a schematic diagram of a case where a welding arc phenomenon is photographed using a high-speed camera of the apparatus of the present invention. That is, the welding arc 3 is generated by the flow supplied from the DC welding power source 1, and the welding wire 7 is melted and transferred to the base metal 8. This welding wire 7 is continuously supplied to the welding arc 3 by a feed roller 10 connected to a motor 9 driven by a control signal from the welding power source 1. The welding current at this time is detected by the current detector 4 and input to the control device 5. The control device 5 compares it with a preset current level and outputs a driving voltage for the electro-optic ceramics 6 according to the input signal. Electro-optic ceramics 6 are inserted between lens 11 and high-speed camera 12.

In the short circuit transition phenomenon, the number of short circuits is up to 120 times/
The short circuit time at this time is about 2 to 3 ms. Therefore, the response speed of the electro-optic ceramics 6 must be less than this, but the electro-optic ceramics 6 used in this device has a response speed of several μs, so it can sufficiently follow welding current fluctuations. . FIG. 4 is a schematic diagram when observing in combination with a video device. In other words, in the figure, 1
3 is a video camera, and a signal from the video camera 13 is recorded by a video coder 14. Alternatively, a video monitor 15 may be connected to observe the image with the naked eye.

FIG. 5 is a detailed explanatory diagram of the control device, in which 16 is an isolation amplifier, 17 is a reference voltage setting resistor, 18 is a comparator, 19 is a transistor,
The rest is the same as in FIG. Next, the operation of the above embodiment will be described. First, when a welding arc 3 is generated by the current supplied from the DC welding power source 1, a voltage commensurate with the current is generated at the output terminal of the welding current detector 4. For example, 50mV at 500A. This voltage is amplified by an insulating amplifier 16, and the welding main circuit and control circuit are insulated to cut unnecessary high frequency components. Next, the signal shaped by the isolation amplifier 16 and the reference voltage setting resistor 17
The comparator 18 compares the voltage signal set by the insulating amplifier 16 with the voltage signal set in the reference voltage, and if the output signal of the isolation amplifier 16 is lower than the reference voltage, a positive voltage is generated at the output of the comparator 18, and as a result, the transistor 19 is turned on. , a high voltage (200V) is applied to the electric shutter 6, and the light-shielding ratio becomes about 1/3 or less of the value before application.

As explained above, according to the present invention, by providing electro-optic ceramics between the light-receiving surface and the optical lens system, the intense light of the welding arc can be used as a spot point.
Even in the short-circuit transition phenomenon of arc welding, which repeatedly disappears, the amount of light incident on the camera or light-receiving surface can be kept almost constant, making it possible to always photograph the welding arc phenomenon under optimal exposure conditions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the automatic diaphragm device of the present invention.
Figure 2 is an explanatory wiring diagram showing the relationship between welding current, arc voltage, and voltage applied to electro-optic ceramics;
FIG. 4 is an explanatory diagram of an embodiment of the welding arc phenomenon photographing apparatus of the present invention, FIG. 4 is an explanatory diagram of another embodiment of the welding arc phenomenon photographing apparatus, and FIG. 5 is a detailed explanatory diagram of the control device. 1... DC power supply, 3... Welding arc, 4... Current detector, 5... Control device, 6... Electro-optic ceramics, 12... High speed camera, 13... Video camera, 16... Insulation amplifier , 18... comparator, 19... transistor.

Claims (1)

[Claims] 1. Electro-optic ceramics that is provided between the light receiving surface of the photographing device and the optical lens system and can control the amount of transmitted light arbitrarily depending on the magnitude of the applied voltage, a welding current detector, and the output of the welding current detector. The device includes a control device that compares the voltage with a reference voltage and changes the voltage applied to the electro-optic ceramic according to the difference between the output voltage and the reference voltage, so as to always maintain a constant amount of light incident on the light receiving surface. A welding arc phenomenon photographing device characterized by: