Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1992-12-02
1994-08-09
Rosenberger, Richard A.
Optics: measuring and testing
By polarized light examination
With light attenuation
356434, G01J 104, B23K 910
Patent
active
053371488
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for monitoring a guard window of an arc sensor mounted on a welding torch of an arc welding robot, and relates more particularly to an apparatus for monitoring a guard window of an arc sensor, which determines the replacement time of the guard window.
BACKGROUND ART
An arc sensor used for searching a welding line of an arc welding robot and otherwise, is mounted on a welding torch of the robot, and because of this, the arc sensor experiences internal structure damage or accumulates stains on the lens as a result of spatterings and lampblack generated during welding. Therefore the arc sensor is provided with a replaceable guard window to guard the internal structure from spatterings and lampblack.
However, this guard window is sometimes burned black by the spatterings and accumulates stains as a result of lampblack and etc. in proportion to the number of welding operations, so that an incident beam and a reflected beam of a laser beam cannot easily penetrate the window. When penetration of the incident beam and reflected beam through the window becomes difficult, the detecting capability of the arc sensor is reduced and the detecting accuracy of the same is also reduced. Therefore, the guard window is usually replaced at determined intervals or as required, or the stains on the window are wiped clean after discerning the accumulated stains on the window with the naked eye.
However, if the guard window is replaced at determined intervals, stains accumulate and replacement thereof is quite often too late, in the case of a large number of welding operations, and as a result, the detecting capability of the arc sensor is reduced. On the other hand, replacement thereof can be too early, and a window is unnecessarily replaced in the case of a small number of welding operations during the determined interval.
Replacement of the guard window as required is indiscriminate and unreliable depending on individual operators thereof, for instance, by discerning accumulated stains with the naked eye, thereby posing the same problem as the case when the windows are replaced at determined intervals.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide an apparatus for monitoring a guard window of an arc sensor, capable of determining the proper replacement time by using an original function of the arc sensor, in the light of the above-mentioned problem.
In order to solve the above-mentioned problem, the apparatus for monitoring the guard window of the arc sensor according to the present invention, which determines the replacement time of the guard window is characterized in that it includes a standard reflecting plate located at a position a determined distance from the front surface of the guard window of the arc sensor; a detecting means that detects a first quantity of light reception from the light reflected when a laser beam scans the standard reflecting plate before the guard window is used for arc welding, and that detects a second quantity of light reception from the light reflected when the laser beam scans the standard reflecting plate after the guard window is used for arc welding; and a judging means to determine the replacement time of the guard window of the arc sensor based on a comparison of the first quantity of light reception and the second quantity of light reception.
First, an unused (brand new) guard window is mounted on an arc sensor, and a standard reflecting plate is then located at the position a determined distance from the front surface of the guard window. The reflected light is detected when the laser beam scans the standard reflecting plate in that state, and data concerning the quantity of light reception is stored in a memory as the first quantity. Then after using the guard window for arc welding operation, the standard reflecting plate is located at a position a determined distance from the front surface of the guard window of the arc sensor. The data concerning the quantity of ligh
REFERENCES:
patent: 4486098 (1984-12-01), Buchegger et al.
patent: 4576482 (1986-03-01), Pryor
patent: 4826316 (1989-05-01), Odum
Patent Abstracts of Japan, vol. 15, No. 196, May 21, 1991.
Patent Abstracts of Japan, vol. 012, No. 460, Dec. 5, 1988.
Week 9033, Derwent Publications Ltd., London, Jul. 26, 1990.
Nihei Ryo
Torii Nobutoshi
Wakio Hiroshi
Fanuc Ltd.
Rosenberger Richard A.
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