Selective Powder-Bed Heating for Stress-Reduced 3D Printing
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Solution Overview
Problem
Existing additive manufacturing methods, such as selective laser sintering, often result in stress issues in three-dimensional objects due to temperature differences between fused and unfused powder materials, particularly with metallic powders, leading to potential stress cracks.
Innovation Solution
A device and method that utilize a selective heating system to maintain a plateau temperature within the construction field, significantly higher than the surrounding areas, with a controlled minimum distance from the edge to reduce thermal stress, allowing for more controlled energy use and consolidation, and incorporating a control unit to adjust heating based on material parameters and thermal behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire construction field is heated to high temperature to reduce temperature difference between fused and surrounding material, then stress cracks are reduced, but energy consumption increases and device components may overheat
Solution Approach 1:
The patent applies local quality by selectively heating only the partial surface region where consolidation occurs, rather than heating the entire construction field. The selective heating device targets specific areas with plateau temperature to maintain sufficient temperature difference for consolidation while avoiding unnecessary heating of surrounding regions, thus reducing overall energy consumption and preventing device component overheating.
Solution Approach 2:
The construction field is segmented into a partial surface region requiring heating for consolidation and surrounding regions that do not require heating. This segmentation allows the selective heating device to apply thermal energy only where needed, resolving the contradiction between reducing stress cracks and minimizing energy consumption.
2Use of energy by moving object
If selective heating is applied to only the consolidation region, then energy consumption is reduced, but temperature difference between fused and surrounding material increases causing stress cracks
Solution Approach 1:
The patent changes the temperature parameter by introducing a plateau temperature that is significantly higher than the surrounding construction field temperature. This temperature parameter optimization ensures that even with selective localized heating, the fused material maintains sufficient thermal energy for proper consolidation and bonding, preventing stress cracks while preserving energy efficiency.
Solution Approach 2:
By applying selective heating only to the consolidation region with elevated plateau temperature, the patent achieves both energy efficiency and stress crack prevention. The localized high temperature zone ensures proper material consolidation while minimizing thermal energy waste in surrounding areas.
3Manufacturing precision
If the construction field is fully heated to activation temperature, then consolidation quality is improved, but the device becomes more complex and energy consumption increases
Solution Approach 1:
The selective heating device provides local quality heating to the consolidation region with plateau temperature, ensuring high consolidation quality without requiring complex full-field heating systems. This localized approach simplifies the overall heating system while maintaining manufacturing precision.
Solution Approach 2:
The patent extracts the heating function from a full-field heating system and concentrates it only in the consolidation region. This extraction simplifies the device by eliminating unnecessary heating components for regions that do not require thermal processing, while maintaining consolidation quality through targeted plateau temperature application.
4Productivity
If plateau temperature is maintained close to activation temperature, then consolidation efficiency is improved, but risk of overheating and stress cracks increases
Solution Approach 1:
The patent optimizes the plateau temperature parameter to be close to but not exceeding the activation temperature. This parameter optimization enables high consolidation efficiency by providing sufficient thermal energy for material bonding, while the selective nature of the heating and the defined temperature relationship prevent overheating and associated stress cracks.
Solution Approach 2:
The control unit monitors and regulates the plateau temperature to maintain it within an optimal range close to activation temperature. This feedback control ensures consolidation efficiency is maximized while preventing temperature excursions that could cause overheating and stress cracks in the consolidated material.
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 enables the production of stress-free three-dimensional objects by optimizing the energy use and thermal management, reducing stress cracks and improving the overall control of the consolidation process, while maintaining energy efficiency and preventing overheating of device components.
Implementation Method 1
a selective heating device (18a, 18b) which is designed so that any given partial surface (19) of the construction field (5) can be heated to a plateau temperature
Implementation Method 2
The plateau temperature can be, e.g., a temperature of the unconsolidated construction material immediately prior to supplying the energy for its consolidation
Implementation Method 3
An example of such a method is known under the name 'selective laser sintering or laser melting'. In this, powder is selectively consolidated by selective irradiation with a laser beam, in that the thermal energy introduced into the material by the laser beam is used to melt the material entirely or superficially
Implementation Method 4
the unconsolidated powderlike construction material surrounding an object being produced serves as an insulator
Data Source
AI summary
A device for the making of a three-dimensional object by means of layer by layer consolidation of a powderlike construction material by electromagnetic radiation or particle beam has a control unit that controls an irradiation device such that the powder particles of the construction material are bonded together at the sites where the radiation impinges on the construction material. A selective heating device is designed so that any given partial surface of the construction field can be heated before and/or after to a plateau temperature, which is significantly higher than the temperature of at least a portion of the construction field outside the partial surface. The control unit actuates the selective heating device such that the partial surface has a predefined minimum distance from the edge of the construction field.