Vat Photocuring Mask Scanning to Limit Resin Heat Buildup
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Solution Overview
Problem
The heating of photo-curable liquid resin during three-dimensional printing, caused by both the exothermic curing reaction and irradiation from UV light sources, leads to temperature exceeding critical limits, resulting in defects and the need for process halts or resin circulation for cooling.
Innovation Solution
A vat polymerization printer with a mask having individually controllable transparent or opaque pixels, controlled by a processor to selectively illuminate regions of the mask, minimizing unnecessary heating by reducing the exposure of opaque pixels and optimizing scan paths to reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light source continuously irradiates the mask to maintain printing throughput, then productivity is improved, but heat generation increases causing resin temperature to exceed critical limits
Solution Approach 1:
The mask is divided into multiple independently controllable pixels that can be selectively switched between transparent and opaque states. This allows only the specific regions requiring curing to receive light exposure while other regions remain dark, thereby reducing overall heat generation in the resin while maintaining printing throughput.
2Temperature
If the printing process is halted periodically to cool the resin, then temperature control is improved, but productivity deteriorates
Solution Approach 1:
The mask pixels are dynamically switched between transparent and opaque states in periodic cycles during the printing process. This periodic modulation of light exposure allows controlled heating followed by cooling periods, maintaining temperature within critical limits without halting the overall printing process.
3Temperature
If a resin circulatory system is used to cool the heated resin, then temperature control is improved, but device complexity increases
Solution Approach 1:
The harmful thermal effect is extracted and eliminated at its source by selectively blocking light exposure to specific mask pixels. This approach removes the need for complex external cooling systems by addressing the heat generation problem directly through optical control rather than thermal management.
4Area of stationary object
If the beam scanner repositions the light beam between transparent regions through opaque regions, then scanning coverage is improved, but heat generation increases
Solution Approach 1:
The mask pixels are pre-configured to identify transparent regions before beam scanning begins. This preliminary setup allows the beam scanner to plan repositioning paths that minimize traversal through opaque regions, reducing unnecessary heat generation while ensuring complete coverage of all transparent regions requiring curing.
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 resin heating, minimizing defects and maintaining printing throughput by selectively illuminating only necessary regions, thus controlling temperature without halting the process.
Implementation Method 1
One obstacle encountered in the three-dimensional printing of objects that involves the curing of photo-curable liquid resin
Implementation Method 2
a mask positioned between the light source and the tank and having pixels configurable to be individually transparent or opaque to portions of the light beam
Implementation Method 3
A beam scanner is configured to scan the light beam across the mask
Implementation Method 4
Not only is the curing of photo-curable liquid resin an exothermic reaction (which locally heats regions of the photo-curable liquid resin where the curing takes place)
Implementation Method 5
the irradiation of a mask by a light source, typically an ultra-violet (UV) light source, also causes heating of the mask. As the mask is located in close proximity to the liquid resin, any heating of the mask also leads to the further heating of the photo-curable liquid resin
Data Source
AI summary
In a vat polymerization printer, a beam scanner scans a light beam across a mask and into a tank containing a photo-curable resin. The mask has pixels configurable to be individually transparent or opaque to portions of the light beam, which has a diameter greater than a cross-sectional dimension of the pixels of the mask. During an exposure time duration, a first subset of the pixels are controlled to be transparent at locations corresponding to the cross section of a three-dimensional object to be printed, while a second subset of the pixels are controlled to be opaque at locations not corresponding to the cross section of the three-dimensional object. The beam scanner is controlled to scan the light beam across the mask such that the light beam is always incident on at least one of the pixels of the mask that are controlled to be transparent.