Electric heating – Metal heating – By arc
Patent
1989-03-02
1990-06-26
Albritton, C. L.
Electric heating
Metal heating
By arc
21912162, 21912183, 36447408, B23K 2600
Patent
active
049374222
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field of the Invention
The present invention relates to a method of correcting the laser output power of a CNC laser beam cutting machine, and more particularly to a laser beam output correcting method capable of automatically compensating for a time-dependent change in the output power of a laser beam.
2. Description of the Background Art
Laser beam cutting machines are being widely used since they may be coupled to numerical control apparatus for cutting workpieces to complex contour at a high speed. For higher cutting accuracy on a laser beam cutting machine, it is necessary to control the output power of a laser beam produced by the laser beam cutting machine. Actually, the output power of a laser beam varies with time because of varying distances between mirrors, varying angles of the mirrors, a loss of a high-frequency power supply, contamination of optical parts such as the mirrors, and other factors. The laser beam output power also varies for seasonal reasons, such as ambient air temperature and the like, and further varies with time dependent on varying ambient air temperature, varying laser gas temperature, and the like. Therefore, the laser beam output power tends to deviate from a certain output command value.
Japanese Patent Application No. 62-107823 filed by the applicant discloses an arrangement for compensating for such time-dependent changes of a laser beam output power. According to the disclosed arrangement, command values and actual laser beam output values corresponding thereto are determined, a table of such command values and actual laser beam output values is prepared, and a command value for obtaining a required laser beam output power is produced from the table, and issued as a command.
With the above method, however, in order to compensate for a time-dependent variation in the output power of a laser beam, the table must be changed by measuring the laser beam output power at certain intervals of time. Unless such a table changing process were effected, no accurate laser beam output power would be achieved. Moreover, such a table changing process is very difficult to carry out since the table has to be changed after the cutting machine has bee delivered to a user. The disclosed correcting operation cannot compensate for short-term variations in the laser beam output power.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a laser beam output correcting method which will solve the aforesaid problems and which is capable of automatically correcting long- and short-term variations in the output power of a laser beam.
To solve the above problems, there is provided in accordance with a first embodiment of the invention a method of correcting the laser beam output power of a CNC laser beam cutting machine composed of a computerized numerical control (CNC) apparatus and a laser beam cutting machine, comprising the steps of:
measuring an actual laser beam output power with an output measuring device with respect to a laser beam output power command value when a laser is initially energized;
determining a correcting coefficient from said laser beam output power command value and said actual laser beam output power; and
controlling the CNC laser beam cutting machine to produce a laser beam output power equal to the command value by referring to the correcting coefficient in an actual cutting operation.
According to a second embodiment invention, there is provided a method of correcting the laser beam output power of a CNC laser beam cutting machine composed of a computerized numerical control (CNC) apparatus and a laser beam cutting machine, comprising the steps of:
measuring an actual laser beam output power at each periodic interval of time with respect to a laser beam output power command value; and
controlling the CNC laser beam cutting machine to eliminate the difference between said laser beam output power command value and said actual laser beam output power.
According to a third embodiment of the invention, there is provided a
REFERENCES:
patent: 3700850 (1972-10-01), Lumley et al.
patent: 4087672 (1978-05-01), Yi
patent: 4504727 (1985-03-01), Melcher et al.
patent: 4730113 (1988-03-01), Edwards et al.
patent: 4812641 (1989-03-01), Oritiz, Jr.
Iehisa Nobuaki
Kinoshita Mitsuo
Nagamine Tsuyoshi
Yamazaki Etsuo
Albritton C. L.
Fanuc Ltd
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