Method for fusing a workpiece

Abstract

Various embodiments of the present invention relate to a method for welding a workpiece comprising the steps of: making a first weld at a first position on said workpiece with a high energy beam, deflecting the high energy beam with at least one deflection lens for making a second weld at a second position on said workpiece, focusing the high energy beam on said workpiece with at least one focusing lens, shaping the high energy beam on said workpiece with at least one astigmatism lens so that the shape of the high energy beam on said workpiece is longer in a direction parallel to a deflection direction of said high energy beam than in a direction perpendicular to said deflection direction of said high energy beam. The invention is also related to the use of an astigmatism lens and to a method for forming a three dimensional article.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61 / 974,304, filed Apr. 2, 2014, the contents of which as are hereby incorporated by reference in their entirety.BACKGROUND[0002]1. Related Field[0003]Various embodiments of the present invention relates to a method for welding a workpiece and a method for forming a three-dimensional article.[0004]2. Description of Related Art[0005]Freeform fabrication or additive manufacturing is a method for forming three-dimensional articles through successive fusion of chosen parts of powder layers applied to a worktable. A method and apparatus according to this technique is disclosed in US 2009 / 0152771.[0006]Such an apparatus may comprise a work table on which the three-dimensional article is to be formed, a powder dispenser, arranged to lay down a thin layer of powder on the work table for the formation of a powder bed, a ray gun for delivering energy ...

AI Technical Summary

Benefits of technology

The present invention provides a method for additive manufacturing using a high energy beam to fuse powder or weld pieces together to a sufficient depth without evaporation. The beam power can be increased while still fusing the powder or welding the pieces together to a sufficient depth while avoiding evaporation. The fusing accuracy or melt width perpendicular to the scanning direction can be kept constant regardless of the beam power and scan speed. The method can use an astigmatism lens to prolong the size of the beam on the layer of powder bed in a direction parallel to the deflection direction more than in a direction perpendicular to the deflection direction. The ratio of the length of the high energy beam in the parallel direction to the perpendicular direction can vary as a function of the power of the energy beam on the workpiece. The use of the astigmatism lens can be widened from the normal use where the beam spot shape is corrected back to its original shape due to distortions introduced in the lens system between the energy beam source and the target surface. The method can include depositing individual layers of powder material that are fused together so as to form the article by shaping the high energy beam with the astigmatism lens.

Problems solved by technology

This may also result in decreased building time.

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