Closed-Loop Pressure Control for 3D Printing Drop Consistency
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Solution Overview
Problem
Existing methods for producing three-dimensional objects using a volume flow of successive drops require long construction times and are sensitive to changes in material viscosity and residence time, leading to inconsistent drop size and pressure fluctuations.
Innovation Solution
The method involves determining the instantaneous initial intrinsic viscosity as a correcting variable for drop size using process control elements, with pressure in the material storage as the control variable, and employing closed-loop control to compensate for viscosity fluctuations and residence time variations, utilizing an injection screw with a non-return valve to manage leakage flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high pressure is applied to discharge material in the form of drops, then the material can be discharged consistently, but the construction time increases and pressure fluctuations occur due to viscosity changes
Solution Approach 1:
The patent implements a closed-loop control system that continuously measures the actual drop volume and compares it to the target drop volume. Based on this feedback, the system dynamically adjusts the discharge pressure to compensate for viscosity changes and residence time effects, maintaining consistent drop size while optimizing construction time
Solution Approach 2:
The system dynamically changes the discharge pressure parameter in response to measured viscosity variations and residence time changes. By adjusting pressure as a controllable parameter based on real-time conditions, the system maintains reliable material discharge without excessive construction time
2Productivity
If the amount of melt in the pressure generator is minimized, then construction time is reduced, but pressure control becomes unstable due to dynamic effects and inertia
Solution Approach 1:
The control system continuously monitors pressure and adjusts the discharge timing and pressure generation in response to actual system conditions. This feedback mechanism allows the system to maintain stable pressure control with minimal melt volume, as the controller can react to dynamic effects in real-time
Solution Approach 2:
The system transitions from static pressure control to dynamic pressure control, where pressure generation and discharge timing are continuously adjusted based on real-time measurements. This dynamic approach enables stable operation with minimal melt volume by adapting to changing system conditions
3Productivity
If the outlet opening is opened frequently for discharge, then material is delivered continuously, but significant dynamic effects on pressure level occur that cannot be tracked
Solution Approach 1:
The system uses continuous pressure measurement and feedback control to track and compensate for dynamic pressure effects during frequent discharge operations. The controller adjusts discharge parameters in real-time to maintain accurate pressure tracking despite frequent opening/closing cycles
Solution Approach 2:
The system performs preliminary measurements of system characteristics and pre-calculates optimal discharge timing and pressure levels. This preliminary action enables accurate pressure tracking during frequent discharge operations by anticipating dynamic effects before they occur
4Adaptability or versatility
If viscosity of the material changes during the production process, then material properties vary, but drop size becomes inconsistent
Solution Approach 1:
The system measures actual drop volume and uses this feedback to detect viscosity changes. When viscosity variation is detected, the control system adjusts discharge pressure and timing to maintain consistent drop size despite changes in material properties
Solution Approach 2:
The system dynamically changes discharge parameters (pressure, timing, duration) in response to measured viscosity changes. By adapting these parameters to compensate for material property variations, the system maintains precise drop size control
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 a constant, discontinuous volume flow, maintaining consistent drop size and reducing construction time by compensating for material viscosity changes and residence time effects, thereby improving the precision and efficiency of the three-dimensional object production process.
Implementation Method 1
a) a fluid phase of a material is introduced into a material storage means, wherein pressure is applied to the fluid phase of the material in the material storage means
Implementation Method 2
utilizing an injection screw with a non-return valve to manage leakage flow
Data Source
AI summary
In a method for discharging a volume flow consisting of successive drops to produce a three-dimensional object of solidifiable material present in a fluid phase, the fluid phase of the material is introduced into a material storage means. A pressure (p) is applied to the fluid phase, in order to discharge the material in drops out of a cyclable outlet opening to build up the three-dimensional object in a construction chamber. A method is provided for achieving a constant, discontinuous volume flow by the pressure (p) being regulated via a closed-loop control in the event of a change in the viscosity of the fluid phase of the material, while maintaining the other process parameters, to achieve a predetermined drop size. The pressure is applied by a conveying element, the average displacement velocity of the conveying element per discharged drop being converted as a measured variable into the control variable for the closed-loop control.