Laser Beam Shaping for Uniform Polymer Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The selective laser sintering process for rapid prototyping is hindered by local temperature peaks that damage polymer materials, causing molecular chain breakage and the release of constituents that disrupt the process, with reducing laser energy insufficient to melt the material effectively.
Innovation Solution
A method and apparatus for layer-by-layer production of three-dimensional objects using a laser beam with a focus maximum power density less than 50% greater than the average power density, achieved through refractive shaping or homogenization of the laser beam, and using nylon-12 polymer powder with a radiation absorber, to prevent molecular weight degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser energy is reduced to avoid local temperature peaks, then the polymer material is protected from damage, but the melting rate decreases markedly
Solution Approach 1:
The patent changes the parameter of laser beam power density distribution by shaping the beam to achieve a more uniform distribution. This transforms the conventional high peak-to-average power density ratio into a lower ratio, preventing local temperature peaks while maintaining adequate overall energy input for effective melting at an acceptable rate.
Solution Approach 2:
The patent employs dynamic control of the laser beam parameters, specifically using beam shaping optics to adjust the power density distribution in real-time during the sintering process. This allows the system to adapt the energy distribution to match the requirements of the polymer material, avoiding both underheating and localized overheating.
2Productivity
If the laser focus maximum power density is high, then the melting efficiency is improved, but local temperature peaks cause molecular chain breakage and constituent release
Solution Approach 1:
The patent applies local quality modification by changing the spatial distribution of laser energy across the powder bed. Instead of a concentrated high-power density spot, the beam is shaped to provide a more uniform, lower peak power density distribution that is adequate for melting without causing localized thermal damage to the polymer molecules.
Solution Approach 2:
The patent introduces beam shaping optics as an intermediary component between the laser source and the polymer powder. This intermediary device modifies the laser beam's power density distribution, acting as a mediator that translates high-power laser energy into a controlled, uniform energy pattern suitable for efficient yet damage-free melting.
3Speed
If the laser focus maximum power density is high, then the melting speed increases, but released constituents deposit on lenses and pyrometers disrupting the process
Solution Approach 1:
The patent modifies the laser beam's power density parameters to achieve a balance where melting occurs at an adequate speed without generating excessive thermal decomposition. The shaped beam provides sufficient average power for effective melting while keeping peak power densities below the threshold for constituent release and subsequent deposition on optical components.
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 ensures the production of three-dimensional objects with minimal molecular weight degradation, maintaining process efficiency by avoiding power peaks and ensuring adequate melting of polymer powders, thus preventing material damage and process disruption.
Implementation Method 1
selectively irradiating portions of the polymer powder layer with a laser beam having an average power density and a focus maximum power density to melt and sinter the irradiated polymer powder
Implementation Method 2
selectively irradiating portions of the polymer powder layer with a laser beam... to melt and sinter the irradiated polymer powder
Implementation Method 3
before irradiation of the polymer powder, the laser beam is shaped such that the focus maximum power density is less than 50% greater than the average power density
Implementation Method 4
In a preferred embodiment the method of the present invention includes at least one of refractively shaping the laser beam and homogenizing the laser beam prior to irradiation of the polymer powder
Implementation Method 5
cooling the melted and sintered powder to obtain a solid mass having a shape
Implementation Method 6
In a highly preferred embodiment, the polymer powder is nylon-12 and in a further highly preferred embodiment, a radiation absorber is added to the nylon-12
Data Source
AI summary
An apparatus and method for the layer-by-layer production of three-dimensional objects wherein a powder layer is melted with a laser beam shaped such that the focus maximum power density is less than 50% greater than the average power density, is provided. Also provided are the corresponding mouldings.