Electric heating – Metal heating – By arc
Patent
1993-11-08
1995-05-23
Paschall, Mark H.
Electric heating
Metal heating
By arc
21912164, B23K 2600, B23K 2614
Patent
active
054183502
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to metallurgy, more particularly techniques of surface treatment by coating or producing surface alloys, and has for its object a nozzle for surface treatment with supply of materials in powder form by laser irradiation, of the coaxial type.
BACKGROUND OF THE INVENTION
The manner of operation of such a coaxial nozzle consists in injecting into a high-power laser beam passing through said nozzle, one or more materials in powder form, also called hard surfacing materials, carried by a fluid, so as to produce, after melting of the materials, a superficial coating layer on the piece to be treated while assuring an excellent adherence by intimate reflow melting of the surface of said piece, or a surface alloy by deep and controlled reflow melting with the material constituting said piece.
This type of nozzle has a structure permitting the free passage of the laser beam and the supply of materials in the form of powder in a peripheral manner, permitting multi-axial treatments, in the three spatial dimensions.
Nevertheless, the quality of the treatment obtained by means of such a nozzle depends particularly on the quantity and the intrinsic properties of the powder supplied to the incident laser beam and on its interaction with said beam, as well as the shape of the resulting jet at the outlet of the nozzle.
Moreover, the possibility of shaping the jet at the outlet of the nozzle permits, on the one hand, to vary the different parameters of treatment such as the region of application, and the intensity of treatment, the distribution of the particles in the impact zone, etc., and, on the other hand, to increase the calorific output of the operation, by coupling in an optimum way the jet of surface hardening materials with the incident laser beam.
Moreover, at present, the hard surfacing materials are generally injected into the laser beam in an empirical way, without using specific supply devices, nor using means to shape the emitted jet. As a result, a large part of the hard surfacing materials are not irradiated by the incident laser beam and therefore do not take part in the treatment of the resulting surface. Furthermore, the; shape of the jet as well as the distribution of the particles in said jet, depending directly on the injection device for the hard surfacing materials, cannot in any case be controlled.
SUMMARY OF THE INVENTION
The present invention has for its object to overcome all of the above drawbacks.
To this end, it has for its object a coaxial nozzle for surface treatment by laser irradiation, with the supply of materials in powder form, characterized in that it is essentially constituted, on the one hand, by a nozzle body provided with a truncated conical passage converging in the outlet direction of the nozzle along the axis of propagation of the laser beam and, on the other hand, by a coaxial injection device, for guiding and shaping a jet of materials, in the form of powder, carried by a transport fluid in said nozzle body and, finally, by an injection device for a confining fluid and pressurizing or generating an underpressure in said treatment nozzle, in the form essentially of a second truncated partition ring extending in a coaxial way within a first partition ring so as to improve the interaction between the incident laser beam and the materials in powder form.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from the following description, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the accompanying schematic drawings, in which:
FIG. 1 is a side elevational cross-sectional view of a treatment nozzle according to the invention;
FIG. 2 is a cross section on the line A--A of the treatment nozzle shown partially in FIG. 1;
FIG. 3 is a cross-sectional view on the line B--B of the treatment nozzle partially shown in FIG. 1, according to a modification of the invention, and,
FIGS. 4, 5 and 6 are photographs of jets emitted by the treatment n
REFERENCES:
patent: 5111021 (1992-05-01), Jolys et al.
patent: 5321228 (1994-06-01), Krause et al.
Freneaux Olivier
Lepre Olivier
Montavon Ghislain
Poulet Jean B.
Electricite de Strasbourg (S.A.)
Institut Regional de Promotion de la Recherche Appliquee
Paschall Mark H.
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