Selective laser solidification apparatus and method

Patent metadata

Field	Value
Publication number	US-2016001401-A1
Application number	US-201414766627-A
Country	US
Kind code	A1
Filing date	Feb 13, 2014
Priority date	Feb 14, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

Selective laser solidification apparatus is described that includes a powder bed onto which a powder layer can be deposited and a gas flow unit for passing a flow of gas over the powder bed along a predefined gas flow direction. A laser scanning unit is provided for scanning a laser beam over the powder layer to selectively solidify at least part of the powder layer to form a required pattern. The required pattern is formed from a plurality of stripes or stripe segments that are formed by advancing the laser beam along the stripe or stripe segment in a stripe formation direction. The stripe formation direction is arranged so that it always at least partially opposes the predefined gas flow direction. A corresponding method is also described.

First claim

1 . Selective laser solidification apparatus, comprising;
a powder bed onto which a powder layer can be deposited, a gas flow unit for passing a flow of gas over the powder bed along a predefined gas flow direction, and a laser scanning unit for scanning a laser beam over the powder layer to selectively solidify at least part of the powder layer to form a required pattern, the required pattern being formed from a plurality of stripes or stripe segments, each stripe or stripe segment being formed by advancing the laser beam along the stripe or stripe segment in a stripe formation direction, wherein the stripe formation direction is always at least partially opposed to the predefined gas flow direction.

2 . An apparatus according to claim 1 , wherein the stripe formation direction subtends an angle (α) of more than 30° to the normal to the gas flow direction.

3 . An apparatus according to claim 1 , wherein the flow of gas over the powder bed originates from a first side of the powder bed and the plurality of stripes are formed in reverse order of their proximity to the first side of the powder bed.

4 . An apparatus according to claim 1 , wherein the gas flow unit comprises at least one gas outlet and at least one gas exhaust, the at least one gas outlet and the at least one gas exhaust being placed either side of the powder bed such that gas pumped from the at least one gas outlet to the at least one gas exhaust provides a substantially planar flow of gas along the predefined gas direction.

5 . An apparatus according to claim 1 ,
wherein the required pattern is formed from a plurality of elongate stripes.

6 . An apparatus according to claim 5 , wherein each of the plurality of elongate stripes comprises a linear stripe having an elongate axis and the stripe formation direction is parallel to the elongate axis.

7 . An apparatus according to claim 1 , wherein the required pattern is formed from a plurality of stripe segments.

8 . An apparatus according to claim 1 , wherein the laser scanning unit generates a laser spot that is moved across the stripe or stripe segment to form a hatch line, each of the plurality of stripes or stripe segments being formed using a plurality of hatch lines that are advanced along the stripe formation direction.

9 . An apparatus according to claim 8 , wherein the laser scanning unit forms the series of hatch lines by moving the laser beam back and forth across the stripe or stripe segment.

10 . An apparatus according to claim 8 , wherein all hatch lines are formed by moving the laser beam in the same line direction across the stripe, the line direction being at least partially opposed to the gas flow direction.

11 . An apparatus according to claim 10 , wherein the line direction is selected based on the orientation of the stripe formation direction relative to the gas flow direction.

12 . An apparatus according to claim 1 , wherein the apparatus deposits and selectively solidifies a plurality of powder layers to form a three dimensional object, the required pattern of each powder layer being formed from a plurality of stripes or stripe segments, wherein the stripe formation direction is always at least partially opposed to the predefined gas flow direction for each stripe or stripe segment of each layer.

13 . An apparatus according to claim 12 , wherein different stripe formation directions are used for adjacent powder layers.

14 . An apparatus according to claim 1 , wherein the laser unit is arranged to selectively melt the powder layer.

15 . A method of selectively solidifying a powder layer deposited on a powder bed, comprising the steps of;
passing a flow of gas over the powder bed along a predefined gas flow direction, and scanning a laser beam over the powder layer to selectively solidify at least part of the powder layer to form a required pattern, the required pattern being formed from a plurality of stripes or stripe segments, each stripe or stripe segment being formed by advancing the laser beam along the stripe or stripe segment in a stripe formation direction, wherein the stripe formation direction always being at least partially opposed to the predefined gas flow direction.

16 . Selective laser solidification apparatus, comprising;
a powder bed onto which a powder layer can be deposited, a gas flow unit for passing a flow of gas over the powder bed along a predefined gas flow direction, and a laser scanning unit for scanning a laser beam over the powder layer to selectively solidify at least part of the powder layer to form a required pattern, the required pattern being formed from a plurality of stripes or stripe segments, wherein the flow of gas over the powder bed originates from a first side of the powder bed and the plurality of stripes or stripe segments are formed in reverse order of their proximity to the first side of the powder bed.

17 . Selective laser solidification apparatus, comprising;
a powder bed onto which a powder layer can be deposited, a gas flow unit for passing a flow of gas over the powder bed along a gas flow direction and, a laser scanning unit for moving a laser beam over the powder layer to selectively solidify at least part of the powder layer to form a required pattern, wherein the laser scanning unit moves the laser beam to form a series of hatch lines that are advanced over the powder layer along a hatch line movement direction, wherein the hatch line movement direction is at least partially opposed to the gas flow direction.

Assignees

• Renishaw Plc

Inventors

• Dimter Marc Frank
• Mayer Ralph Markus
• Hess Thomas

Classifications

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B33Y30/00

  Apparatus for additive manufacturing; Details thereof or accessories therefor · CPC title

• B28B1/001

  Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material (selective deposition modelling of metallic powder B22F10/00; rapid manufacturing of 3D objects in general and in particular of plastics B29C64/00) · CPC title

• B33Y50/02

  for controlling or regulating additive manufacturing processes · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title