Boots – shoes – and leggings
Patent
1988-03-07
1990-08-21
Ruggiero, Joseph
Boots, shoes, and leggings
21912434, 364513, 901 42, 901 47, G06F 1546, B23K 912
Patent
active
049512188
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method to be used in an arc welding for detecting positional information such as a welding groove position, a welding torch height, a welding start point, a welding end point, an external or internal corner point, a work contact point of a welding wire or a welding groove gap by monitoring the shape and/or position of a welding arc.
BACKGROUND TECHNIQUE
In the prior art, a method has been known for controlling the welding position and condition or the like of the arc welding by picking up the image of a portion to be welded such as a molten metal, a welding tip, a wire or a welding groove with the use of industrial TV camera (ITV) and by analyzing the image picked up.
However, the arc flame has a more intense brightness than that of the surroundings (e.g., the molten metal) and contains much infrared and ultraviolet rays so that difficult problems are encountered in detecting the welding portion
Therefore, the following solutions have been worked out in the prior art.
One solution is to devise an image pickup or an optical filter. In Japanese Patent Laid-Open No. 51-72938, for example, the radiation from the portion being welded is transmitted only in the visible and near infrared ranges by providing filters for limiting infrared rays, heat rays, colors and quantities of light, respectively, and by using a silicon vidicon image pickup tube in the TV camera. In Japanese Patent Laid-Open No. 59-212172, on the other hand, the image is picked up by an infrared TV camera through an infrared filter. In Japanese Patent Laid-Open No. 58-159980, moreover, the filter is dispensed with by using a CCD (i.e., a charge-coupled device or solid image sensor) as the image pickup device.
Another method for solving the influences of the arc is to provide a high-speed shutter in the industrial TV camera. In Japanese Patent Laid-Open No. 58-7776, for example, the shutter is opened only upon short-circuiting of the arc by catching the chance of arc disappearance. In Japanese Patent Laid-Open No. 59-202178, on the other hand, the shutter is opened in the pulse welding operation only when the arc attenuates at the timing of a base current.
Still another method for picking up the image of a portion being welded while discriminating the arc is to provide a light source for the image pickup. In Japanese Patent Laid-Open No. 55-42185, for example, the light source has a spectral distribution different from that of a disturbance light such as the arc, and the wavelength to be detected falls within a wavelength range in which the quantity of the disturbance light is smaller than that of the light source. In Japanese Patent Laid-Open No. 59-191574, on the other hand, a light source is provided for projecting a beam forward of the running direction of a welding torch to represent the image of the welding groove in a contour defined by shadows.
What can be commonly said among the various prior art examples described above is to separate and remove the image to be picked up and the arc partly because the object to be picked up is the portion to be welded such as the molten metal and partly because the arc is the disturbance light obstructing the image pickup.
Since, however, the arc has a high intensity and a wavelength covering substantially the whole range, it can hardly be completely removed, and the system therefor has to become complex and expensive.
In the case of narrow gap welding operation, on the other hand, some example monitors the arc itself. In Japanese Patent Laid-Open No. 55-45554, for example, the luminance distribution of the arc is determined to locate the center of rotations of the welding core wire in the gap. In Japanese Patent Laid-Open No. 58-187268, on the other hand, the movement of the torch is controlled by providing an optical detector at the leading end of the torch and by comparing the outputs of the detector.
However, the above examples are limited to the narrow gap welding operations but cannot be applied to the lap, fillet and butt joint welding operat
REFERENCES:
patent: 4280137 (1981-07-01), Ashida et al.
patent: 4567348 (1986-01-01), Smith et al.
patent: 4667082 (1987-05-01), Shibata et al.
Ito Hiroaki
Nakazato Tatsumi
Nishikawa Seigo
Okumura Shinji
Kabushiki Kaisha Yaskawa Denki Seisakusho
Ruggiero Joseph
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