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1. (WO2018146441) METHOD OF AND APPARATUS FOR ADDITIVE LAYER MANUFACTURE

Pub. No.:    WO/2018/146441    International Application No.:    PCT/GB2018/000019
Publication Date: Fri Aug 17 01:59:59 CEST 2018 International Filing Date: Thu Feb 01 00:59:59 CET 2018
IPC: B22F 3/105
B29C 64/153
B29C 64/393
Applicants: RELIANCE PRECISION LIMITED
Inventors: RICHARDSON, William Thomas
LAIDLER, Ian
BLUNT, Liam
Title: METHOD OF AND APPARATUS FOR ADDITIVE LAYER MANUFACTURE
Abstract:
A method of additive layer manufacture comprises the steps of successively depositing layers of fusible powder material in overlying relationship (S1, S17) and introducing energy, such as by an electron beam, into each deposited layer to selectively melt material in the layer (S9) so as to fuse the melted material together and to already fused material of a layer thereunder in order to produce a three-dimensional solid article in successive cross-sectional layers. In order to monitor layer quality, structured light defining a fringe pattern is projected onto each deposited layer before (S2) and/or after (S10) melting of material in that layer and the fringe pattern on each layer is imaged (S3; S11) from a perspective different from that of the projection so as to reveal disturbance of the pattern by topographical features of the layer. Any such revealed disturbance is then assessed in the context of analysis of the fringe pattern image to recognise defects in the respective layer of powder material if the structured light was projected onto that layer before melting (S4, S5, S7) or defects in a cross-sectional layer of the article formed from that powder material layer if the structured light was projected onto that layer after melting (S12, S13, S15). Finally, layer deposition is correctively influenced in the case of recognition of defects in the powder material layer (S6, S8) and energy introduction is correctively influenced in the case of recognition of defects in the article cross-sectional layer (S14, S16).