Heat treating using a laser
AssigneeCoherent, Inc.
InventorRichard J. Saunders
Life of this patent
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Abstract
A method and apparatus are disclosed utilizing a laser for heat treating a transformation hardenable workpiece. Sufficiently high laser power densities are provided at the workpiece surface to cause an incandescent reaction with the workpiece, but incandescent reaction is limited to a sufficiently short period of time to prevent any substantial melting of the workpiece. Pre-conditioning the workpiece prior to heat treatment, squelching the workpiece with a gaseous jet, and techniques for work-hardening cylindrical workpieces are also disclosed.
Claims29
A method of heat treating a transformation hardenable workpiece comprising the steps of:
- directing a laser beam onto the surface of the workpiece at sufficiently high power densities to cause an incandescent reaction above the workpiece melting temperature with the workpiece;
- and
- limiting the incandescent reaction at any given area of the workpiece surface to a sufficiently short period of time to prevent any substantial melting of the workpiece.
A method of heat treating a cylindrical shaft of a transformation hardenable material without substantial distortion comprising the steps of:
- directing a laser beam to the outside surface of the cylindrical shaft at sufficiently high power densities so as to cause a substantially instantaneous incandescent reaction above the melting temperature of the material with the shaft;
- limiting the dwell time of the laser beam at any given point on the surface of the shaft to prevent any substantial melting of the shaft by
- (i) rotating the shaft about its longitudinal axis,
- (ii) traversing the laser beam longitudinally along the outside surface of the rotating shaft, whereby a spiral shaped heat-treated band is formed on the cylindrical shaft,
- (iii) forming the laser beam into a thin line of light at the shaft, with the line of light oriented in a direction parallel with the longitudinal axis of the shaft;
- (iv) pre-conditioning the shaft to be heat treated with a uniform coating of a material which is absorbtive of the laser beam wavelength, and
- (v) selecting the rotational speed of the shaft and the laser beam scanning rate such that the resulting heat treated spiral band is separated by a non-heat treated spiral band.
Apparatus for heat treating a transformation hardenable workpiece comprising:
- means for directing a laser beam onto the surface of the workpiece at sufficiently high power densities to cause an incandescent reaction above the melting temperature of the material with the workpiece;
- and
- means for limiting the incandescent reaction at any given area of the workpiece surface to a sufficiently short period of time to prevent any substantial melting of the workpiece.
Apparatus for heat treating a cylindrical shaft of a transformation hardenable material without substantial distortion comprising:
- means directing a laser beam to the outside surface of the cylindrical shaft at sufficiently high power densities to cause a substantially instantaneous incandescent reaction above the melting point of the material with the shaft;
- means for limiting the dwell time of the laser beam at any given point on the surface of the shaft to prevent any substantial melting of the shaft, said limiting means comprising:
- (i) means for rotating the shaft about its longitudinal axis,
- (ii) means for traversing the laser beam longitudinally of the rotating shaft, whereby a spiral shaped heat-treated band is formed on the cylindrical shaft,
- (iii) means for forming the laser beam into a thin line of light oriented in a direction parallel with the longitudinal axis of the shaft,
- (iv) means for pre-conditioning the shaft to be heat treated with a uniform coating of a material which is absorbtive of the laser beam wavelength, and
- (v) means for selecting the rotational speed of the shaft and the laser beam scanning rate such that the resulting heat treated spiral band is separated by a non-heat treated spiral band.
Dependencies are inferred from the claim text.