Selective Preheating for Additive Manufacturing Thermal Stress Reduction
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Solution Overview
Problem
Existing additive manufacturing methods face challenges with thermal stresses and defects such as warping due to rapid temperature changes, which affect the quality and dimensional accuracy of the produced objects, particularly in processes like powder bed fusion and selective laser sintering.
Innovation Solution
A method and system that incorporates selective localized preheating of building material regions before exposure, using radiation sources, to control the temperature-time profile and prevent unnecessary heating, allowing for improved material preservation and multi-material additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the building material is rapidly heated from room temperature to writing temperature (e.g., 20°C to 160°C or higher) using a light source, then the material can be hardened or become sticky for layer formation, but significant thermal stresses occur causing warping and defects
Solution Approach 1:
The patent applies preliminary action by heating regions surrounding the intended writing area before actual material exposure. This preheating step raises the temperature of adjacent regions to near-writing temperature, so that when the writing beam arrives, the thermal gradient is minimized and thermal stresses are reduced, preventing warping and defects
Solution Approach 2:
The patent implements local quality by applying different thermal treatments to different regions of the building material layer. Specifically, regions surrounding the writing area receive preheating treatment while the writing area itself receives controlled exposure. This localized approach ensures each region experiences appropriate temperature changes, minimizing overall thermal stress while maintaining manufacturing precision
2Reliability
If the entire layer of building material is heated uniformly, then thermal stresses are distributed evenly, but material properties deteriorate faster and usability is reduced
Solution Approach 1:
The patent applies local quality by restricting thermal exposure to specific regions surrounding the writing area rather than heating the entire layer uniformly. This localized preheating approach maintains material properties in unexposed regions, extending material usability while still providing sufficient thermal preparation where needed
Solution Approach 2:
The patent extracts the harmful thermal exposure from the entire material layer and confines it only to regions surrounding the writing area. By removing unnecessary thermal exposure from distant regions, the patent preserves material properties and extends usability while maintaining the beneficial thermal effects where required
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 reduces thermal and mechanical stresses, enhances the quality and dimensional accuracy of the objects, extends the usability of building materials, and enables more efficient manufacturing processes by maintaining material properties and reducing waste.
Implementation Method 1
selectively preheating, using radiation from at least one radiation source, the one or more identified predetermined regions
Implementation Method 2
selectively exposing, using radiation from at least one radiation source, the one or more predetermined regions, for writing the layer of the tangible object
Data Source
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AI summary
A method and system for layerwise production of a tangible object, whereby the object is built up layer per layer by repeatedly providing a layer of building material onto a carrier and repeatedly performing method cycles. Each method cycle including selectively exposing, using radiation from at least one radiation source, one or more predetermined regions, for writing the layer of the tangible object. The one or more identified predetermined regions are selectively preheated prior to selectively writing these identified regions in a same method cycle. During selective preheating a temperature of the one or more preheating regions is locally increased from an initial temperature to an elevated preheating temperature remaining below a writing temperature of the building material in said preheating regions.