Method and apparatus for laser heat treatment for metal wire

#1. Field of the Invention

#The present invention relates to a method and apparatus for laser heat treatment for a metal wire, especially for a steel wire used for automotive tires and so forth.

#2. Description of the Related Art

#FIG. 1 is a schematic illustration showing an apparatus for the heat treatment of a steel wire according to the present invention;

#FIG. 2 is an enlarged section showing one example of a mirror angle adjusting mechanism to be employed in the apparatus of FIG. 1;

#FIG. 3 is an illustration showing another example of a mirror angle mechanism to be employed in the apparatus of FIG. 1;

#The present invention will be discussed herebelow in detail with reference to the accompanying drawings.

#FIG. 1 is a diagrammatic illustration showing one example of a facility for laser heat treatment employing a conical mirror 1 of the present invention. The conical mirror 1 is made from sheet metal, such as a copper plate and formed into a conical shaped configuration. The inner surface 2 is processed into a mirror surface by plating of gold and so forth or by polishing so that an incident laser beam can be easily reflected. It should be noted that the configuration of the mirror is not specified to be a conical shaped configuration but can be a polygonal cone shaped configuration. In the case of a polygonal cone shaped configuration of the mirror, the peak angle .theta. (angle to the tangent of inscribing circle) is preferably in a range of 5.degree. to 20.degree.. The top end of the conical mirror 1 defines an outlet opening 4 for a metal wire 3 that is to be subject to heat treatment. The diameter of the output opening 4 is set to be greater than the metal wire 3 in a range of 0.2 to 2 mm. A deflecting mirror 5 is provided on the bottom of the conical mirror 1 for deflecting a laser beam toward the interior of the conical mirror. The deflecting mirror 5 is oriented to the mirror surface thereof essentially at 45.degree. with respect to the axis of the conical beam. The deflecting mirror 5 is provided with a mirror angle adjusting mechanism 6 (see FIGS. 2 and 3) that permits the adjustment of the orientation of the mirror surface of the deflecting mirror 5 in a range of .+-.10.degree..

#In the drawings, the reference numeral 7 denotes a laser beam generator. The laser beam 8 discharged from the laser beam generator 7 irradiated onto the deflecting mirror 5 through deflecting mirrors 9, 9 and a window 10 defined through the periphery of the conical mirror 1 and then irradiated into the interior of the conical mirror. The reference numeral 11 denotes a feeding device for the metal wire 3, which adjusts the feed speed for feeding the metal wire through the conical mirror 1 at a predetermined speed. The reference numeral 12 denotes an inlet opening for the metal wire 3 defined through the deflecting mirror 5. The reference numeral 13 denotes gas inlets for introducing non-oxidation gas into the conical mirror 1 for establishing a non-oxidizing atmosphere within the interior space of the conical mirror.