Selective Solidification Scanning During Wiper Motion
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Solution Overview
Problem
Existing selective laser melting and sintering apparatus take a long time to build objects, often days or even weeks for large objects, due to the limitations in consolidating powder layers during the layer-by-layer solidification process.
Innovation Solution
The apparatus and method involve scanning the energy beam across powder layers during multiple strokes of the wiper, consolidating powder regions both before and after the wiper movement, and adjusting the beam focus to maintain a consistent spot size despite changes in powder bed height, allowing simultaneous powder spreading and platform lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the energy beam scans across the powder layer after the wiper has finished forming the layer, then the powder can be consolidated, but the build time increases significantly
Solution Approach 1:
The energy beam performs preliminary consolidation action on the powder layer while the wiper is still in motion, before the layer formation is complete. This allows the powder to be partially consolidated during the layer formation process itself, rather than waiting for a separate consolidation step after the wiper finishes, thereby reducing total build time while maintaining consolidation quality
Solution Approach 2:
The energy beam operates continuously during the wiper's movement across the powder bed, rather than operating in separate sequential steps. The scanner directs the energy beam to consolidate powder on both sides of the wiper simultaneously as the wiper moves, ensuring continuous useful action and eliminating idle time between layer formation and consolidation operations
2Area of stationary object
If the wiper travels the entire length of the powder bed to form layers, then complete coverage is achieved, but the time required for each layer increases
Solution Approach 1:
The energy beam performs preliminary consolidation on powder regions that will be covered by the wiper's subsequent passes. By consolidating powder on both sides of the wiper during its movement, the system prepares areas for future layer formation without requiring the wiper to make additional dedicated consolidation passes, reducing total time while maintaining complete coverage
Solution Approach 2:
The system adds the time dimension to the wiper's spatial movement by operating the energy beam simultaneously during the wiper's traversal. Instead of sequential operations (wiper finishes then energy beam operates), the operations occur in parallel during the same time window, effectively utilizing another dimension of the process space to reduce total cycle time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces build time by optimizing the scanning strategy and enabling consolidation during wiper movement, thus accelerating the layer-by-layer solidification process.
Implementation Method 1
A laser beam is then scanned across portions of the powder layer that correspond to a cross-section of the object being constructed. The laser beam melts or sinters the powder to form a solidified layer.
Implementation Method 2
The laser beam melts or sinters the powder to form a solidified layer.
Implementation Method 3
The laser beam melts or sinters the powder to form a solidified layer.
Data Source
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AI summary
This invention concerns a selective solidification apparatus comprising a build chamber (117), a build platform (102) lowerable in the build chamber (117), a wiper (109) for spreading powder material across the build platform (102) to form successive powder layers of a powder bed (104), an energy beam unit (105) for generating an energy beam (118) for consolidating the powder material, a scanner (106) for directing and focussing the energy beam (118) onto each powder layer and a processor (131) for controlling the scanner (106). The processor (106) is arranged to control the scanner (106) to scan the energy beam across the powder bed (104) to consolidate powder material either side of the wiper (109) when the wiper (109) is moving across the powder bed (104) and to scan the energy beam (118) across at least one of the powder layers during two or more strokes of the wiper (109) across the powder bed (104).