ADDITIVE LAYER MANUFACTURING

• US 20150041025A1
• Filed: 03/18/2013
• Published: 02/12/2015
• Est. Priority Date: 03/19/2012
• Status: Active Grant

• Current Assignee: BAE Systems Plc
• Original Assignee: BAE Systems Plc
• Inventors: Wescott, Andrew David, Sidhu, Jagjit
• Granted Patent: US 10,427,247 B2
• Time in Patent Office: Days
• US Class Current: 148/538
• CPC Class Codes: B22F 10/25 Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/364 for post-heating, e.g. remelting
• CPC Class Codes: B22F 10/50 Treatment of workpieces or articles during build-up, e.g. treatments applied to fused layers during build-up
• CPC Class Codes: B22F 12/20 Cooling means
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 12/43 pulsed; frequency modulated
• CPC Class Codes: B22F 12/45 Two or more
• CPC Class Codes: B22F 12/47 parallel to the deposition plane
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/70 Gas flow means
• CPC Class Codes: B22F 2202/01 Use of vibrations
• CPC Class Codes: B22F 2202/03 Treatment under cryogenic or supercritical conditions
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/144 the fluid stream containing particles, e.g. powder
• CPC Class Codes: B23K 26/32 taking account of the properties of the material involved
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B23K 26/356 by shock processing
• CPC Class Codes: B23K 26/703 : Cooling arrangements by using a fluid stream B23K26/14
• CPC Class Codes: B23K 31/003 : relating to controlling of welding distortion
• CPC Class Codes: B23K 35/0244 : Powders, particles or spheres; Preforms made therefrom
• CPC Class Codes: B23K 35/0261 : Rods, electrodes, wires
• CPC Class Codes: B23K 9/042 : Built-up welding on planar surfaces
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 : Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: C21D 10/005 : by laser shock processing
• CPC Class Codes: C21D 2251/00 : Treating composite or clad material
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

Apparatus and a method for forming a metallic component by additive layer manufacturing are provided. The method includes the steps of using a heat source such as a laser to melt the surface of a work piece and form a weld pool; adding wire or powdered metallic material to the weld pool and moving the heat source relative to the work piece so as to progressively form a new layer of metallic material on the work piece; applying forced cooling to the formed layer; stress relieving the cooled layer by applying a peening step, for example with a pulsed laser, and repeating the above steps as required to form the component layer by layer.

Claims

1. A method of forming a metallic component by additive layer manufacturing, the method comprising:

using a heat source to apply heat to a portion of a surface of a work piece sufficient to melt said portion;

adding metallic material to the melted portion and moving the heat source relative to the work piece so as to progressively form a layer of metallic material on the work piece;

c) applying forced cooling to the formed layer to bring the layer to a state of crystallisation;

d) stress relieving the cooled layer; and

repeating the using, adding, applying, and stress relieving as required to form the component.

2. A method as in claim 1 in which the additive layer manufacturing method is selected from the group of:

laser blown powder manufacture, laser powder bed manufacture, and wire and arc manufacture.

3. A method as in claim 1 in which the stress relieving comprises applying high frequency peening to the cooled layer.

4. A method as in claim 3 in which the high frequency peening comprises applying a pulsed laser to the cooled layer.

5. A method as in claim 3 in which the high frequency peening step comprises applying ultra-sonic impact treatment to the cooled layer.

16. A method as in claim 1 in which the method is computer-aided.

6. Additive layer manufacturing apparatus for manufacturing a metallic component, the apparatus including a treatment station that is movable relative to a work piece, the treatment station including a heat source, a source of metallic material, a cooling source, and

a stress reliever, the heat source being sufficient to melt a portion of a surface of the work piece together with metallic material being fed into the heat source to form an added layer of metallic material on the work piece, the cooling source being adapted to cool the added layer to a state of crystallisation, and the stress reliever being adapted to provide energy to the added layer so as to relieve stress in the added layer.

7. Apparatus as in claim 6 in which the stress reliever is adapted to be applied specifically to the added layer so as to modify the microstructure of the added layer.

8. Apparatus as in claim 7 in which the stress reliever comprises a pulsed laser whereby to apply laser peening to the added layer.

9. Apparatus as in claim 7 in which the stress reliever comprises ultrasonic impact treatment whereby to apply ultrasonic energy to the added layer.

10. Apparatus as in claim 6 in which the heat source comprises a laser configured to be focused upon the work piece surface and the source of metallic material comprises a powder and gas delivery device adapted to deliver gas carrying the metal powder substantially to the focal point of the laser.

11. Apparatus as in claim 6 in which the heat source comprises a laser configured to be focused upon the work piece surface and the source of metallic material comprises a powder bed in which the work piece is to be positioned and wherein the bed is filled with metallic powder substantially to a level of the work piece surface.

12. Apparatus as in claim 6 in which the heat source comprises a welding arc and the source of metallic material comprises a metallic wire held on a feed, the arc being positioned so as to create a weld pool on the surface of the work piece and the feed being adapted to feed the wire to the weld pool.

13. Apparatus as in claim 6 in which the cooling source comprises forced gas cooling.

14. Apparatus as in claim 6 in which the cooling source comprises cryogenic cooling.

15. Apparatus as in claim 6 including an applicator to deposit a sacrificial covering upon the cooled added layer.

17. Apparatus as in claim 6 in which the heat source comprises a laser configured to be focused upon the work piece surface and the source of metallic material comprises a powder bed in which the work piece is to be positioned.

18. Additive layer manufacturing apparatus for manufacturing a metallic component, the apparatus comprising:

a treatment station that is movable relative to a work piece, the treatment station including a heat source, a source of metallic material, a cooling source, and a stress reliever, the heat source being sufficient to melt a portion of a surface of the work piece together with metallic material being fed into the heat source to form an added layer of metallic material on the work piece, the cooling source being adapted to cool the added layer to a state of crystallisation, and the stress reliever being adapted to provide energy to the added layer so as to relieve stress in the added layer;

wherein the cooling source comprises forced gas cooling or cryogenic cooling;

wherein the stress reliever is adapted to modify the microstructure of the added layer, and comprises a pulsed laser whereby to apply laser peening to the added layer or ultrasonic impact treatment whereby to apply ultrasonic energy to the added layer;

wherein the heat source comprises a laser configured to be focused upon the work piece surface, or a welding arc; and

wherein the source of metallic material comprises a powder and gas delivery device adapted to deliver gas carrying the metal powder substantially to the focal point of the laser, or a powder bed in which the work piece is to be positioned, or a metallic wire held on a feed, the welding arc being positioned so as to create a weld pool on the surface of the work piece and the feed being adapted to feed the wire to the weld pool.

19. Apparatus as in claim 18 including an applicator to deposit a sacrificial covering upon the cooled added layer.