Selective Deposition Additive Manufacturing Thermal Transfer
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Solution Overview
Problem
In electrophotographic 3D printing, porous surface layers of constructed parts lead to thermal inefficiencies and potential weakening of the part due to tortuous thermal paths and impedance mismatches for phonon transfer, as well as difficulties in eliminating trapped gas, which becomes challenging as layers are added.
Innovation Solution
A selective deposition-based additive manufacturing system that uses an electrostatographic imaging engine to develop layers of thermoplastic powder, with a build platform and rotatable belt for transferring and heating layers, employing a heat transfer liquid to heat and cool the part build surface in a controlled manner, ensuring each layer is fully consolidated before the next is added.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If layers are added sequentially in electrophotographic 3D printing, then the part can be built layer by layer, but porosity accumulates and thermal efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by fully consolidating and fusing each layer before adding the next layer. The system uses heated pressing plates and controlled pressure to ensure complete fusion of the current layer into the part body before proceeding to deposit and fuse the subsequent layer. This preliminary consolidation prevents porosity accumulation and maintains thermal efficiency throughout the building process.
Solution Approach 2:
The patent implements continuity of useful action through continuous heating and pressing during the layer fusion process. The heated pressing plates maintain elevated temperature and pressure throughout the layer consolidation phase, ensuring continuous thermal energy transfer and complete fusion. This continuous action eliminates air pockets and ensures uniform density, preventing the deterioration of thermal efficiency that would occur with intermittent or insufficient consolidation.
2Ease of manufacture
If porous layers are present in the constructed part, then layer deposition is simplified, but thermal paths become tortuous and heat transfer is impeded
Solution Approach 1:
The patent applies parameter changes by controlling the temperature and pressure parameters during layer fusion to transform the physical state of the powder material. The heated pressing plates raise the temperature of each layer to above the glass transition temperature of the polymer material, while applied pressure densifies the layer. These parameter changes convert the loose porous powder structure into a dense, fused solid structure with continuous thermal paths, dramatically improving thermal conduction efficiency.
Solution Approach 2:
The patent effectively creates a composite structure where fully fused layers with high density and continuous polymer matrix are formed through controlled heating and pressing. This composite approach ensures that each layer becomes a homogeneous, non-porous unit with excellent thermal conductivity, eliminating the tortuous thermal paths that would exist in porous structures while maintaining the layer-by-layer manufacturing advantage.
3Productivity
If layers are quickly deposited to increase production speed, then productivity improves, but consolidation and fusion become insufficient
Solution Approach 1:
The patent applies preliminary action by dedicating sufficient time and energy to the consolidation and fusion of each layer before proceeding to the next deposition step. The heated pressing plates are applied with controlled pressure for optimized durations to ensure complete fusion of the powder material. This preliminary consolidation action, performed at the appropriate stage before next layer deposition, maintains manufacturing precision while enabling continuous high-speed layer-by-layer production.
Solution Approach 2:
The patent implements periodic action through a cyclic process of rapid layer deposition followed by controlled heating and pressing consolidation. The system alternates between quick powder deposition phases and thorough fusion phases, with each cycle optimized for both speed and quality. This periodic rhythm of deposit-then-consolidate allows high productivity while ensuring each layer achieves complete fusion and consolidation before the next layer is added.
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 enhances thermal efficiency and part strength by ensuring each layer is fully fused and consolidated, reducing porosity and thermal impedance, resulting in improved thermal properties and structural integrity of the printed 3D parts.
Implementation Method 1
A first heater is configured to heat a part build surface of the 3D part, supported by a build platform, by impinging a first heat transfer liquid toward the part build surface to transfer heat to the part build surface
Implementation Method 2
pressing one of the developed layers on the transfer surface of the transfer belt into contact with the heated part build surface to heat the developed layer to a flowable state by conduction from the part build surface
Implementation Method 3
A cooling unit is configured to cool the new part build surface to remove heat energy
Data Source
AI summary
Disclosed are selective deposition-based additive manufacturing systems (10) and methods for printing a 3D part (26). Layers of a powder material (22) are developed using one or more electrostatographic engines (12a-d). The layers (22) are transferred for deposition on a part build surface (88). For each of the layers (22), the part build surface (88) is pre-heated by impinging a first heat transfer liquid (74) toward the part build surface (88), for example using a solder fountain. The developed layer (22) is pressed into contact with the heated part build surface (88) to heat the developed layer (22) to a flowable state and form a new part build surface (88) which is fully consolidated. The new part build surface (88) is then rapidly cooled to remove the heat energy added during heating step before repeating the steps for the next developed layer (22).