Method and apparatus for additive manufacturing of a workpiece

A method of additively manufacturing a workpiece from a powder material, comprising the steps of:

• a) providing
• a device for receiving a powder bed of the powdery material in a vacuum process chamber, and
• a beam generator adapted to direct an energy beam to laterally different locations of the powder bed;
• b) layer-by-layer application of the powdery material to the powder bed;
• c) layer-by-layer production of the workpiece in the powder bed by selective bonding of the powdery material by the energy beam;
• wherein
• d) during the production of the workpiece, in addition to the workpiece, cooling structures are produced in the powder bed by selective bonding of the powdery material by the energy beam, the cooling structures being arranged to dissipate heat, wherein the cooling structures are designed in such a way that
• powdered material remains between the cooling structure and the device for receiving a powder bed as well as between the cooling structure and the workpiece,
• the cooling structures extend to an uppermost final layer of the powder bed when production of the workpiece is completed,
• the cooling structures have a cross-sectional area which is largest in the final layer,
• the cooling structures are terminated by termination segments, and that
• the final layer of the powder bed is formed entirely from the termination segments arranged in a grid pattern and separated by channels of unmelted powder, and
• e) after step d) cooling at least one of the workpiece and the powder bed in the vacuum process chamber by dissipating heat via the cooling structures.