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

[0019]In still another example embodiment of the present invention a ratio of a length of said high energy beam in said parallel direction and said perpendicular direction is also varying as a function of the position of said high energy beam on said workpiece. A non-limiting advantage of at least this embodiment is that the protraction of the beam spot is not only beam power dependent but also depending on the pattern which is to be fused.

[0020]In yet another example embodiment of the present invention a mean spot size on said workpiece in a direction perpendicular to the scanning direction is smaller than a mean spot size on said workpiece in a direction parallel to the scanning direction for a full scan length, a full cross section and / or for a full 3-dimensional article. A non-limiting advantage of at least this embodiment is that one may choose for which part of the build the mean spot size in a direction parallel to the scanning direction is longer than the mean spot size in a direction perpendicular to the scanning direction.

Problems solved by technology

This may also result in decreased building time.

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