Electric heating – Metal heating – By arc
Patent
1989-04-17
1991-04-02
Albritton, C. L.
Electric heating
Metal heating
By arc
21912162, 36447408, B23K 2600
Patent
active
050048899
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for controlling laser power, and more particularly to such a method for improving a synchronism between a moving speed of the machine system and the laser output control.
BACKGROUND ART
Laser machining apparatuses have been extensively used in conjunction with numerical control systems, since such an arrangement facilities complex shape machining of a workpiece at high speed. Generally, no problems exist in machining a workpiece along a straight line or a curve of a large radius of curvature. However, if the output of the laser beam is not controlled in accordance with the moving speed of the workpiece during machining of corner portions or acutely angled edge portions thereof, welding losses occur due to build up of thermal energy and excessive heat absorption, resulting in decreased machining accuracy and causing to degradation of the material of the workpiece.
In order to avoid such drawbacks, a laser output controlling method has been proposed in Japanese patent application No. 62-107824 whereby the laser output is controlled in accordance with machining speed during machining of edge portions.
Conventionally, as in the above-mentioned application, the laser output is controlled in response to an instructions regarding the moving speed of the workpiece as calculated by a machining program.
However, with such a laser output controlling method, there is a significant time delay between the occurrence of the instruction and the movement of the mechanical system controlled by the instruction due to the inertia of the mechanical system. On the other hand, substantially no time delay is involved in outputting the laser beam, since the laser output is controlled by a current flowing in a discharge tube.
Specifically, the response time of the laser output is smaller by approximately a factor of two than that of the mechanical system. The control of the laser output in response to the moving instructions for the mechanical system causes a loss of synchronism between the moving speed of a work table and the laser output. For this reason, there have been cases where machining accuracy and machining performance were not sufficiently attained.
DISCLOSURE OF THE INVENTION
An object of the present invention is to resolve the above mentioned problems and to provide a laser power controlling method in which the synchronism between the moving speed of a machine system and the laser output control is improved.
In order to resolve such problems, a laser power controlling method is provided where in the laser output is controlled by a numerical control (NC) instruction as a function of an instruction regarding the moving speed of a mechanical system, the method comprising the steps of:
Providing an instruction regarding said moving speed to a simulator approximated to a mechanical system with a first-order or second-order function and
generating a laser output instruction based on the result obtained by said simulator,
whereby synchronism between the moving speed of the mechanical system and the laser output control is assured.
By providing the moving speed instruction to the simulator which has the basic characteristics of the mechanical system, the movement of a workpiece mounted on a table may be synchronized with the laser power output irradiated onto the workpiece, thereby improving cutting performance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an arrangement of an apparatus which may be used for carrying out the method according to one embodiment of the present invention;
FIG. 2 is a flowchart illustrating the software for processing the method according to the embodiment of an invention; and
FIG. 3 is a block diagram illustrating first-order simulation processing.
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an arrangement of an apparatus used in carrying out a method according to one embodiment of the
REFERENCES:
patent: 4870560 (1989-09-01), Seki et al.
patent: 4914599 (1990-04-01), Seki et al.
Patent abstracts of Japan, vol. 9, No. 77 (M-369) (1800) Apr. 6, 1985, & JP-A-59 206192 (Mitsubishi Denki K.K) Nov. 22, 1984.
Iehisa Nobuaki
Suzuki Kazuhiro
Yamazaki Etsuo
Albritton C. L.
Fanuc Ltd.
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