Rheology Estimation in 3D Printing Supply Lines
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Solution Overview
Problem
Existing additive manufacturing processes for producing three-dimensional objects from curable binder compositions, such as concrete, face challenges due to the difficult interplay between the material and the application device, particularly due to the non-Newtonian rheological properties and curing kinetics of these compositions.
Innovation Solution
A method involving the production of a curable binder composition in a setting state, its conveyance via a supply line to a printing head, and application layer-by-layer, while determining a pressure drop and optionally flow rate and temperature in the supply line to estimate the rheological properties of the binder composition in real time, allowing for immediate adjustments to maintain consistent quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Coriolis type sensor is used to measure physical properties of wet mortar, then density, flow, viscosity, and temperature can be measured simultaneously, but the measurements are highly difficult and give unreliable results
Solution Approach 1:
The patent extracts the measurement function from complex multi-parameter sensors (Coriolis sensors) and implements separate, dedicated sensors for each physical property (pressure sensors for pressure drop, flow meters for flow rate, temperature sensors for temperature). This separation simplifies each measurement task and improves reliability by avoiding the complexity of simultaneous multi-parameter measurement with a single sensor system.
Solution Approach 2:
The patent introduces an intermediary calculation approach where rheological properties are not measured directly but derived from intermediate measurements (pressure drop, flow rate, temperature) through established relationships. This intermediary method allows reliable rheological property determination without requiring direct complex measurement of these difficult-to-measure properties.
2Stability of the object's composition
If the mixing ratio of mortar composition is controlled based on unreliable sensor measurements, then stable physical properties can be obtained, but the control quality is not fully satisfying for 3D printing applications
Solution Approach 1:
The patent implements a feedback control system that continuously monitors pressure drop, flow rate, and temperature, calculates rheological properties in real-time, and adjusts the mixing ratio accordingly. This closed-loop feedback ensures both composition stability and printing quality by making continuous adjustments based on actual process conditions rather than relying on fixed or poorly measured parameters.
Solution Approach 2:
The patent dynamically adjusts the mixing ratio parameters (proportions of cement, sand, water, and additives) based on real-time rheological property calculations. By changing these composition parameters in response to measured conditions, the system maintains optimal rheological properties for 3D printing while ensuring consistent composition quality.
3Device complexity
If rheological properties of curable binder composition are not monitored, then the process is simpler, but blocking of the print head and uncontrolled material flow occur
Solution Approach 1:
The patent performs preliminary measurement and calculation of rheological properties (viscosity, yield stress) before material reaches the printing head. By assessing flow conditions upstream and predicting potential blocking or uncontrolled flow issues, the system can take preventive actions (adjusting mixing ratio, flow rate, or temperature) before problems occur, thereby maintaining reliability without excessive complexity.
Solution Approach 2:
The patent replaces direct mechanical monitoring of the printing head (which would add complexity) with upstream sensor measurements and computational rheological analysis. By using pressure sensors, flow meters, and temperature sensors combined with mathematical models to predict rheological behavior, the system achieves reliable process control through measurement and calculation rather than direct mechanical intervention.
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 high-quality printed three-dimensional objects by maintaining constant rheological properties, preventing blockages in the print head, and avoiding uncontrolled material flow, thus enhancing the safety and reliability of the additive manufacturing process.
Implementation Method 1
Determining a pressure drop over a length section of the supply line with one or more pressure measuring device(s)
Implementation Method 2
estimating a rheological property of the curable binder composition in the supply line, in particular the viscosity, based on the determined pressure drop and, especially, based on the determined flow rate and the determined temperature
Data Source
AI summary
A method for producing a three-dimensional object from a curable binder composition with an additive manufacturing process, the method including the steps of: producing the curable binder composition in the setting state, preferably by mixing the constituents of the curable binder composition in a mixing unit, conveying the curable binder composition in the setting state via a supply line to a printing head movable in at least one spatial direction, applying the curable binder composition in the setting state by means of the printing head, wherein the curable binder composition is preferably applied layer-by-layer, to form the three-dimensional object, determining a pressure drop over a length section of the supply line with at least two pressure measuring device(s), optionally, determining a flow rate of the curable binder composition in the supply line, optionally determining a temperature of the curable binder composition in the supply line.