JPS5815778B2 - High speed photography device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus suitable for photographing objects moving at high speed, particularly for photographing welding arc phenomena.

For example, in arc welding, photographing, recording, and analyzing arc phenomena are extremely important for research on improving welding rods and welding methods.

However, the welding arc phenomenon is irregular and fluctuates rapidly;
Moreover, it emits strong light, so it cannot be observed with the naked eye.

Another option is to take a picture with a regular camera and observe it, but the phenomenon is so fast that the image is blurred.

For example, in the spray transfer phenomenon of droplets in MIG welding, the transfer speed of droplets is as high as 2 to 3 ml seconds.

If we assume that the speed is 3 m/sec, the maximum shutter speed of a general camera is about 1/1000 sec, and when shooting at this shutter speed, the image will move by 3 mm.

This simulated diagram is shown in Figure 1. Even if the real image is as shown in Figure 1a, the image obtained by photographing will be as shown in b.

For these reasons, it is common to use a high-speed cine camera to observe welding arc phenomena.

The (1) intermittent lowering type and (2) prism type are widely used as high-speed cine cameras, but both are inappropriate for elucidating welding arc phenomena in detail.

In other words, high-speed intermittent lowering cameras can obtain good image quality because both the optical system and the film surface are completely stationary during exposure, but if you try to increase the shooting speed, the inertia increases and the simple mechanism In this case, it is impossible to fix the film at a fixed position all the time.

Therefore, the maximum shooting speed of the current intermittent lowering type high-speed cameras is about 1000 frames per second, and if you shoot the welding arc phenomenon at this shooting speed, the image will be blurred because the phenomenon is fast as described above. .

In addition, a prism-type high-speed camera continuously feeds film, and a rotating prism for correction is inserted between the photographing lens and the film to prevent image blurring caused by this.

The shooting speed can be easily increased compared to an intermittent drop-down type high-speed camera, but there is an error between the amount of image movement due to prism rotation and the amount of film movement, chromatic aberration occurs when passing through the prism, and if the prism is tilted Due to the effects of astigmatism that occurs when used in

Furthermore, since the film size used is generally 16 mm, the image becomes unclear when it is enlarged.

In view of the above, it is an object of the present invention to provide a high-speed photographing device capable of sufficiently clearly photographing extremely fast welding phenomena, such as droplet spray transfer phenomena in MIG welding, which are difficult to photograph.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 is an exploded view, in which 1 is an optical system lens, 2 is a camera body having a light receiving surface, and a dark box 3 is provided between the optical system lens 1 and the camera body 2.

The dark box 3 is constructed by fixing a concave plate 3a having a recess 4 and a flat plate 3b, and a slit 5 is provided in the recess 4.
A rotating disk 6 having a diameter is housed therein.

A variable speed motor 7 is attached to the rotating disk 6 to rotate it at a variable speed.

8 is a controller for controlling the rotation speed of the variable speed motor 7.

Reference numeral 9 denotes a rotation speed detector for detecting the rotation speed of the rotating disk 60, and is attached to the flat plate 3b.

A display 10 displays the number of revolutions of the rotating disk 60 based on an input signal from the detector 9.

Reference numeral 11 denotes an object to be detected, which is fixed on the rotating disk 6 at a position symmetrical to the center of the slit 5.

Reference numeral 12 designates a position detector, and there are various magnetic or optical methods for detecting the rotation speed. For example, when a magnetic method is adopted, a magnetic proximity switch is used as the position detector 12 to detect the rotation speed. The disk 6 has a non-magnetic material and a detected object 11.
A magnetic material is used for this purpose.

Reference numeral 13 denotes a measuring device, into which the output signal of the position detector 12 and the signal of the X contact of the camera body 2 are input, and the waveforms of these signals can be recorded.

Further, although not shown, welding current and voltage waveforms from a welding machine are input to the measuring device 13, and these signal waveforms can be recorded.

Therefore, when the slit 5 crosses the optical axis, the detected object 1
1 also reaches the position closest to the position detector 12, and therefore the position detector 12 also outputs a signal.

Note that since the position detector 12 has such a function, it can also be used as a rotation speed detector.

When photographing the welding arc phenomenon using the device configured as described above, the number of rotations of the rotating disk 60 is N (r, p, s).
, the distance from the center of the rotating disk 6 to the slit 5 is r(m
m), the circumferential speed S of the rotating disk 6 at the position of the slit 5 is
is S=2 yrrN (mm7 seconds).

Therefore, if the slit width is 1, then the shutter speed V will be.

For example, if the rotation speed N of the motor 7 is 15r, p, 5 (=90
Or, p, m), the distance r from the center of the rotating disk 6 to the slit 5 is set to r=160 mm, and the slit width l is set to 1 mm, then the shutter speed V is as follows.

In this case, if the shutter speed of the camera body 2 is set to 1/15 seconds, the shutter of the camera body 2 will be open for the time it takes for the rotating disk 6 to rotate once, that is, 1/15 seconds, so double exposure is possible. Alternatively, the phenomenon can be reliably photographed without exposure errors.

As mentioned above, the shutter speed is determined by the distance r from the center of the rotating disk to the slit 5, the rotation speed N, and the slit width l, but if the slit width l is too narrow, the effects of diffraction, interference, etc. will be large. Therefore, it is preferable to set it to 0.5 mm or more.

The motor 7 that rotates the rotating disk 6 has a rotational speed N of 70 to 1500.
r, plm variable induction motor.

Further, a 35 mm size film is used for the camera body 2.

FIG. 3 shows welding current and voltage waveforms recorded on the measuring device 13 using an electromagnetic oscillograph, the output waveform of the position detector 12, and the signal waveform from the camera.

The welding method is short-circuit arc welding using CO2 gas.

The output signal of the position detector 12 is output every time the rotary disk 6 rotates once, but the X contact signal of the camera body 2 is output only while the shutter is open.

Therefore, the phenomenon that is photographed during this period is the phenomenon that occurs at the moment when the position detector 12 outputs while the X contact signal is being output.

FIG. 4 shows an example of a welding arc phenomenon photographed using the device of the present invention at a shutter speed of 1,715,000 seconds.

This is a droplet spray transfer phenomenon in MIG welding using a mild steel welding core wire with a diameter of L2 mm.

The transfer rate of droplets during spray transfer was set to 3 as described above.
Assuming that the speed is m/sec, the distance to 17150000 seconds is 0.2 mm, so it can be almost ignored.

As described above, according to the apparatus of the present invention, even objects that move at high speed, such as extremely fast welding arc phenomena such as the spray transfer phenomenon of droplets in MIG welding, can be accurately and clearly photographed.

[Brief explanation of the drawing]

Figures 1a and b are simulation diagrams of the spray transfer phenomenon of droplets in MIG welding, Figure 2 is an exploded view of the high-speed photographing device of the present invention, and Figure 3 is an explanatory diagram of double exposure prevention of the present invention device. FIG. 4 is also an explanatory diagram of the spray transfer phenomenon of droplets. 1...Optical system lens, 2...Power camera body, 3...Dark box,
5... Slit, 6... Rotating disk, 7... Variable speed motor, 8... Controller, 9... Rotation speed detector, 10...
Display device, 11...Detected object, 12...Position detector, 13
...Measuring instrument.

Claims (1)

[Claims] 1. In a high-speed imaging device in which a dark box is provided between the light-receiving surface and the optical system lens, and a rotating disk with a slit is housed in the dark box, the rotating disk has a variable speed motor and a rotating speed of the variable speed motor. A high-speed imaging device characterized in that the dark box is provided with a rotation speed detector for detecting the rotation speed of the rotating disk, and a position detector for detecting the position of the slit. .