Additive Manufacturing Cooling Control for Layer Temperature Gradients
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Solution Overview
Problem
Additive manufacturing of metal parts faces challenges in effectively dissipating heat and controlling temperature gradients, leading to undesirable characteristics such as micro-cracks and thermal-induced residual stress due to excessive temperature buildup during the formation process.
Innovation Solution
A method and system utilizing cryogenic fluid-cooled nozzles to control the temperature gradient between layers by measuring sidewall and top layer temperatures and adjusting cooling intensity to maintain the temperature gradient below predetermined maximum values, employing a direct energy deposition process like wire-arc additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heat dissipation techniques are used (chilling substrate, cooling medium immersion, cold rolling, cryogenic fluid, CO2 cooling spray), then heat removal is attempted, but temperature gradients between layers and excessive temperatures in additive layers are not adequately controlled
Solution Approach 1:
The cooling system is segmented into multiple independently controllable cooling zones, with separate cooling circuits for the substrate and for individual layer regions. This allows differential cooling rates to be applied to different parts of the workpiece, enabling precise control of temperature gradients between layers while removing excess heat.
Solution Approach 2:
Different regions of the workpiece receive different cooling intensities based on their specific thermal requirements. The substrate receives one cooling regime while individual layers receive customized cooling, allowing each region to maintain optimal temperature gradients for preventing defects while achieving overall temperature control.
2Ease of manufacture
If higher temperatures are used to melt and form metal layers, then additive manufacturing of metal parts is achieved, but excessive temperature buildup occurs leading to micro-cracks and thermal-induced residual stress
Solution Approach 1:
Cooling measures are applied immediately after each layer is deposited, before excessive heat can diffuse to subsequent layers. The substrate cooling and layer-specific cooling are activated in advance and maintained continuously, preventing temperature buildup that would lead to micro-cracks and residual stress while allowing the high-temperature deposition process to proceed.
Solution Approach 2:
The system incorporates temperature monitoring and control mechanisms that provide feedback on the thermal state of the workpiece. This allows real-time adjustment of cooling intensity to maintain temperatures within the optimal range for metal layer formation while preventing excessive heat accumulation that compromises part integrity.
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 effectively reduces temperature gradients and prevents harmful thermal-induced stress, improving the mechanical properties and service life of the metal parts by maintaining temperatures within safe limits during the additive manufacturing process.
Implementation Method 1
providing a plurality of coolant nozzles in fluid flow communication with a cryogenic fluid
Implementation Method 2
controlling a cooling intensity of each of the plurality of coolant nozzles
Implementation Method 3
forming a metal part comprising a plurality of layers using a direct energy deposition additive manufacturing process
Data Source
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AI summary
A method and system for providing cooling to a part formed using high-temperature additive manufacturing process. Infrared sensors or cameras are used to measure sidewall temperatures and, optionally, top layer temperature. Coolant nozzles provide cooling to the sidewalls of the finished layers and, optionally, to the top layer. The coolant intensity of the coolant nozzles is controlled in order to reduce temperature gradients between layers and/or to maintain temperatures in each layer below preferred maximum temperature.