Composite Manufacturing Method for Complex Internal Structures
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Solution Overview
Problem
Current additive-subtractive composite manufacturing methods based on powder bed fusion (PBF) are restrictive due to the influence of the powder bed, limiting the formation of complex internal structures and requiring support structures that are difficult to remove, leading to deformation and accuracy issues.
Innovation Solution
A method that includes model preprocessing, decomposition, and reconstruction, utilizing a self-supporting design and T-shaped milling cutters to enable support-free printing of large-angle overhanging internal cavity structures, combined with post-processing to remove internal supports and improve surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If support structures are added for large-angle overhang structures in PBF additive manufacturing, then thermal deformation and scraper force are resisted, but the internal supports are difficult to remove and cause deformation when removed, affecting overall part accuracy
Solution Approach 1:
The patent divides the support structure removal process into multiple stages corresponding to different construction layers. The swing head performs CNC machining at different heights during the additive manufacturing process, removing support structures layer by layer rather than all at once. This segmented approach prevents sudden stress release and deformation that would occur if all supports were removed simultaneously.
Solution Approach 2:
The patent implements preliminary removal of support structures during the additive manufacturing process itself, before the part is completely built and removed from the build platform. The swing head performs preliminary CNC machining operations to remove supports at intermediate stages, preventing the accumulation of internal stresses that would cause deformation upon final support removal.
2Manufacturing precision
If PBF process is used for additive manufacturing, then high surface accuracy and fine structures are achieved, but the construction direction is single and the swing head cannot process below the powder bed surface
Solution Approach 1:
The patent merges PBF additive manufacturing with CNC subtractive machining in a single integrated system. The swing head equipped with CNC machining tools is combined with the PBF build platform, allowing the system to perform both additive layer deposition and subtractive precision machining operations. This combination enables the swing head to process below the powder bed surface by removing powder and machining the part interior, overcoming the limitation of single-direction construction.
Solution Approach 2:
The swing head is designed with multi-functionality, capable of performing both additive manufacturing operations (positioning for laser sintering) and subtractive CNC machining operations. This universal tool can switch between adding material layers and removing material for internal feature creation, enabling complex internal structures to be manufactured without being constrained by the single construction direction limitation of pure PBF processes.
3Productivity
If DED method is used for composite manufacturing, then rapid manufacturing and part repairing are enabled, but surface accuracy is lower compared to PBF method
Solution Approach 1:
The patent implements continuous alternate processing where additive manufacturing and CNC machining operations are performed in succession without removing the part from the build platform. The swing head alternates between PBF additive layers and CNC machining operations in a continuous workflow, maintaining productivity while progressively improving surface accuracy. This continuous action eliminates idle time for part removal and repositioning, preserving the productivity advantage of DED while adding the precision benefit of CNC machining.
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 allows for integrated precision manufacturing of complex internal structures with improved surface quality and shape control, overcoming the limitations of traditional PBF methods by enabling the removal of internal supports and enhancing the accuracy of large-angle overhang structures.
Implementation Method 1
metal additive-subtractive composite manufacturing methods... powder bed fusion (PBF)... direct energy deposition (DED)
Implementation Method 2
powder bed fusion (PBF)... more suitable for integrated precision manufacturing of complex internal structures
Data Source
AI summary
A composite manufacturing method based on powder bed and five-axis additive and subtractive materials includes model Preprocessing: processing model adaptive compensation based on a design model and repairing the model after model compensation to obtain an additive model; decomposition and reconstruction: decomposing the additive model to obtain multiple sub-models that can plan the internal surface tool path at one time, and then processing additive manufacturing and CNC machining alternately for the sub-models according to the build sequence until composite manufacturing of all sub-models is completed; and post-processing: removing support structure and milling outer surface of the part after composite manufacturing of all sub-models is completed, in addition, after the influence of the powder bed and support is removed, reprocessing a non-machined part of internal structure to obtain a final required part. The present invention can realize the manufacturing of parts with complex internal structures that are difficult to process by traditional CNC machining and provides technical support for the integrated precision manufacturing of complex internal structure parts.