Spatial Light Modulation for Powder Bed Temperature Control
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Solution Overview
Problem
Existing powder-based additive manufacturing systems face challenges in achieving precise temperature control within the build chamber and powder layer, which affects the mechanical properties, surface finish, and dimensional accuracy of 3D objects.
Innovation Solution
The use of a spatial light modulator, such as a digital light projector (DLP), to control the temperature of the powder bed by applying modulated radiation, combined with a temperature measurement device and a heated gas supply for pre-heating and recirculation, allows for precise temperature control and selective fusion of powder layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If radiant heaters are used for temperature control, then the build chamber and powder layer can be heated, but the temperature control precision is insufficient
Solution Approach 1:
The heating system is divided into multiple independent radiant heater zones that can be individually controlled. Each zone corresponds to specific measurement locations, allowing localized temperature adjustment and improved precision without requiring complex centralized control.
Solution Approach 2:
Temperature measurements from the powder layer and build chamber are fed back to the control system, which automatically adjusts the power output of individual heater zones to maintain target temperatures, thereby improving temperature control precision through closed-loop control.
2Productivity
If higher energy is applied to heat the powder layer, then the heating speed increases, but the energy consumption increases
Solution Approach 1:
The powder layer is pre-heated to a target temperature before the selective laser sintering process begins. This preliminary heating reduces the energy required during the actual sintering operation, as the laser only needs to provide the temperature differential for fusion rather than heating from ambient temperature, thereby improving heating efficiency and reducing total energy consumption.
Solution Approach 2:
Different zones of the powder bed receive different amounts of radiant heating based on their specific requirements. Areas that need faster heating receive higher energy input, while areas that are already near target temperature receive reduced energy, optimizing the overall energy distribution and reducing total energy consumption while maintaining productivity.
3Productivity
If the powder layer is heated to higher temperatures, then the fusing process is accelerated, but the dimensional accuracy decreases
Solution Approach 1:
The powder layer is pre-heated to a controlled target temperature that is optimized for subsequent laser sintering. This pre-heating step brings the powder closer to the fusing temperature in a controlled manner, allowing the laser to complete the fusion process quickly while maintaining dimensional accuracy, as the temperature profile is carefully managed throughout the process.
Solution Approach 2:
The heating system dynamically adjusts the temperature profile during the manufacturing process. The radiant heaters provide a baseline temperature that is continuously monitored and adjusted, allowing the system to maintain optimal conditions for both fusing speed and dimensional accuracy by adapting to changing process conditions in real-time.
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 improved temperature control, reducing energy consumption and build time, while ensuring optimal mechanical properties and accuracy of 3D objects by maintaining the powder at specific temperatures for fusing and process conditions.
Implementation Method 1
A radiation source applies radiation that is visible light and/or infrared (IR) radiation or radiation with a wavelength of at least about 400 nanometers (nm) to a layer of powder defining an image plane
Implementation Method 2
A temperature measurement device measures a temperature of the powder layer defining the image plane at one or more locations
Implementation Method 3
The radiation source comprising the spatial light modulator may also apply the radiation to selectively fuse the powder layer of the image plane
Implementation Method 4
During formation of a 3D object, layers of powder are selectively solidified at the image plane
Data Source
AI summary
Methods and apparatus are provided for controlling the temperature of powders in a powder-based additive manufacturing system using spatial light modulation. Powder layer temperatures can be measured and selectively controlled using a radiation source comprising a spatial light modulator. The spatial light modulator applies a visible light radiation and/or IR radiation. In addition to controlling the pre-fused temperature of the powder in the image plane, the spatial light modulator can also apply the radiation to fuse the powder.