Electric heating – Metal heating – By arc
Patent
1986-10-23
1988-08-02
Albritton, C. L.
Electric heating
Metal heating
By arc
21912163, 21912167, 21912174, B23K 2600
Patent
active
047615346
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to laser apparatus. Processing by the application of a laser beam (e.g. for cutting or welding a metal workpiece) is well known and it is an object of this invention to provide improved apparatus for effecting such operations.
According to the present invention there is provided laser apparatus for performing operations on a workpiece, the apparatus comprising a laser source, means for focusing a laser beam from said source onto the workpiece, computing means, surface sensing means remote from the workpiece and associated with the computing means for determining a representation of a surface of the workpiece, and means associated with the computing means for causing the focused laser beam to move relatively across a surface of the workpiece in accordance with parameters entered into the computing means.
Preferably the apparatus additionally comprises a housing in which the workpiece may be located.
In a first embodiment of the invention, the means for focusing the laser beam is positioned remote from the workpiece and is of variable focal length.
This focusing means may, for example, be pivotal so that the beam scans across the workpiece. During this scanning the focal length of the focusing unit is controlled so that the beam is always focused at the surface of the workpiece.
This embodiment of the invention overcomes a disadvantage of prior art apparatus in which a laser focusing head is moved in close proximity to a workpiece. In such prior apparatus splashes of molten material from the workpiece may enter the focusing head due to its close proximity to the workpiece. This molten material could solidify on the lens and cause considerable difficulties and often catastrophic failure of the lens. Failure of the lens unit would render the whole system inoperable until a replacement could be fitted. In hazardous conditions, e.g. radioactive contamination of the work enclosure, several problems concerning operator safety could be successful replacement of the lens. These problems are overcome by the first embodiment of the invention.
In a second embodiment of the invention, the focusing means may be mounted on a flexible beam guide, and the movement of the focusing means across the workpiece is controlled by a robot. Such an apparatus provides for totally automatic operation which is particularly useful for performing laser processing applications in hazardous environments.
The invention will be further described by way of example only with reference to the accompanying drawings in which:
FIG. 1 is a schematic representation of one embodiment of apparatus in accordance with the invention;
FIG. 2 is a detail of one embodiment of a variable focal length focusing unit for use in the apparatus shown in FIG. 1;
FIG. 3 shows a further embodiment of variable focal length focusing unit;
FIG. 4 is a schematic representation of a second embodiment of apparatus in accordance with the invention; and
FIG. 5 is a detail of FIG. 4.
The apparatus illustrated in FIG. 1 comprises:
a. Workpiece Housing 1,
b. Laser beam source (external to the housing) 2,
c. Beam focusing unit 3 remotely positioned from the workpiece, and used for focusing the laser beam from the source 2 onto the workpiece,
d. Beam deflectors 5 serving to direct the beam from source 2 to the focusing unit 3,
e. Remote surface sensing unit 7 used to determine the profile of the workpiece surface,
f. Computing unit 8 used to process information gathered from the remote surface sensing unit 7 and direct the scanning control unit (see below),
g. Scanning control unit 9 used to `steer` the focused laser beam via the beam focusing unit 3,
h. Focus control unit 10 receiving commands derived from the processed information via the remote surface sensing unit 7 and computing unit 8 to accurately focus the laser beam via the beam focusing unit 3 and,
i. Nozzle 11 whose function will be described by example in later paragraphs.
It is intended that the illustrated apparatus be used for processing large workpieces in harsh or hazardous environme
REFERENCES:
patent: 3571555 (1971-03-01), Townes et al.
patent: 4049945 (1977-09-01), Ehlscheid et al.
Albritton C. L.
N.I.S. Limited
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