Dual-Beam Powder Bed Preheating for Additive Manufacturing Crack Control
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Solution Overview
Problem
Existing additive manufacturing methods for components, particularly those using powder bed fusion, fail to achieve sufficient preheating temperatures across the entire component height, especially when processing nickel- or cobalt-based superalloys, leading to inadequate weldability and increased cracking tendencies due to residual stresses.
Innovation Solution
A method involving dual selective irradiation with a first energy beam and a second energy beam arranged in a ring-shaped manner, combined with aselective heating of the layer to achieve temperatures between 400°C and 500°C, reducing both macro- and micro-residual stresses and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional platform heating is used for preheating, then the build platform can be heated to approximately 200°C, but the preheating temperature is insufficient to significantly reduce residual stresses and the effect decreases significantly with increasing build height
Solution Approach 1:
The patent applies local quality by using aselective heating that can heat different regions of the powder bed to different temperatures. The heating device is designed to heat the powder bed in a controlled manner, creating optimal temperature conditions in specific zones while maintaining overall temperature control. This allows sufficient preheating temperature to be achieved where needed without overheating other areas.
Solution Approach 2:
The patent changes the temperature parameter from conventional platform heating (approximately 200°C) to aselective heating that can achieve temperatures between 400°C and 500°C in the powder bed. This parameter change is achieved through controlled heating rates and holding times, transforming the thermal state of the material to improve weldability and reduce residual stresses.
2Reliability
If high preheating temperatures (400-500°C) are applied to improve weldability of nickel- or cobalt-based superalloys, then cracking tendency is reduced, but heat conduction is insufficient and the preheating effect decreases significantly with increasing build height
Solution Approach 1:
The patent applies preliminary action by heating the powder bed to the target temperature range (400-500°C) and holding it at that temperature for a specified time before beginning the additive manufacturing process. This preheating action is performed in advance to ensure the material is in the optimal thermal state for welding, reducing cracking tendency and improving weldability before the actual manufacturing begins.
Solution Approach 2:
The patent maintains continuous heating and temperature control throughout the additive manufacturing process. The heating device continues to supply thermal energy to maintain the powder bed temperature within the optimal range (400-500°C) throughout the build process, ensuring consistent preheating effect across the entire component height and preventing temperature gradients that would reduce weldability.
3Reliability
If the powder bed is heated to high temperatures to prevent hot or solidification cracks, then crack prevention is improved, but severe sintering of the surrounding powder occurs
Solution Approach 1:
The patent applies dynamics by using dynamic temperature control with different heating rates and holding times for different stages of the process. The heating is not static but adapts to the specific requirements of each manufacturing stage, allowing the system to achieve crack prevention temperatures temporarily while controlling overall sintering through controlled exposure time and localized heating zones.
Solution Approach 2:
The patent uses periodic heating cycles with controlled heating rates, holding periods, and cooling phases. This periodic action allows the material to reach optimal temperatures for crack prevention while limiting the total time at high temperature, thereby preventing severe sintering of the surrounding powder. The cyclic nature of the heating allows controlled thermal exposure.
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
The method effectively reduces residual stresses and improves weldability of difficult-to-weld alloys by preventing cracking and enhancing surface quality and resolution, while maintaining a controlled temperature gradient.
Implementation Method 1
selectively irradiating a layer of a powdered material to build up the component layer by layer, in particular by selective laser sintering, selective laser melting
Implementation Method 2
aselective heating of the layer to a temperature of at least one-quarter of a temperature which the layer experiences during the selective irradiation
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for powder bed additive manufacturing of a component (2). The method comprises the selective irradiation of a layer (10) made of a powder material (7) with a first energy beam (14) and a second energy beam (15), that is different from the first, wherein the second energy beam (15) annularly surrounds the first energy beam (14), and the aselective heating of the layer (10), wherein a large part of the layer (10) is heated to a temperature (T1) that is at least one quarter of the temperature (T2) that the layer (10) is heated to as a result of the selective irradiation. The invention also relates to a corresponding device.