3D Printing Extrusion Pump Control for Consistent Bead Deposition
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Solution Overview
Problem
Existing 3D printing methods using extruders face challenges in maintaining a consistent bead size due to variations in extrusion rate and heat energy, leading to inconsistent print quality, especially when printing large or complex objects.
Innovation Solution
Implementing a servo-controlled fixed-displacement pump and coordinated speed control between the extruder and polymer pump to synchronize speed changes, ensuring a consistent flow rate and bead size by adjusting the extruder speed in proportion to the polymer pump speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional extruder is used to melt and extrude thermoplastic material, then the material can be deposited layer by layer, but the extrusion rate varies due to changes in heat energy and screw speed, resulting in inconsistent bead size
Solution Approach 1:
The system employs a feedback control mechanism where the actual extrusion rate is monitored and compared to the target extrusion rate. The screw speed is then adjusted based on this feedback to maintain consistent bead size. The controller receives signals about the actual extrusion rate and modifies the screw rotation speed accordingly to compensate for variations in heat energy and material flow.
Solution Approach 2:
The patent replaces the traditional mechanical extruder system with an electric pump system that delivers molten thermoplastic material. This substitution allows for more precise control of material flow rate through electronic control of the pump motor, eliminating the inconsistencies associated with mechanical screw extrusion and heat-dependent viscosity changes.
2Productivity
If the screw speed is increased to improve productivity, then more material can be extruded, but the heat energy becomes insufficient to melt the material properly, causing variations in bead size
Solution Approach 1:
The patent replaces the friction-based mechanical melting system with an electrically heated system. The electric pump motor can be controlled independently of temperature, allowing high-speed material delivery without relying on friction-generated heat. This enables maintaining both high productivity and proper material melting through separate control of flow rate and heating elements.
Solution Approach 2:
The system changes the controlling parameters from mechanical friction and heat-dependent viscosity to electrically controlled pump speed and independent heating. This allows decoupling of the extrusion rate from temperature variations, enabling consistent bead size even at higher productivity levels where traditional extruders would fail to melt material adequately.
3Manufacturing precision
If the screw speed is decreased to maintain consistent bead size, then the extrusion rate becomes stable, but the productivity decreases and large items cannot be manufactured efficiently
Solution Approach 1:
The electric pump system enables high-speed material delivery without the viscosity and heat constraints that limit traditional extruders. The pump can maintain consistent flow rates at higher speeds through electronic control, dramatically reducing printing time for large items while preserving bead size consistency that would otherwise require slow extrusion speeds.
Solution Approach 2:
The system changes the operational parameters by using electrically controlled pump speed instead of mechanically coupled screw speed. This allows the extrusion rate to be increased significantly while maintaining stability through electronic feedback control, reducing total printing time for large components without sacrificing manufacturing precision.
4Manufacturing precision
If a servo-controlled system is implemented to coordinate extruder and pump speeds, then the flow rate consistency is improved, but the device complexity increases
Solution Approach 1:
The servo-controlled system uses feedback from flow rate sensors to continuously adjust pump and extruder speeds. The controller compares actual flow rate with target flow rate and modifies motor speeds accordingly, achieving high flow rate consistency. While this adds control system complexity, it enables precision that outweighs the added complexity, especially for large-scale manufacturing.
Solution Approach 2:
The controller serves multiple functions: it controls both the extruder motor and pump motor, monitors flow rate, adjusts speeds coordinate, and maintains bead size consistency. This multi-functionality consolidates what could be multiple separate control systems into a single integrated unit, reducing overall system complexity despite the sophisticated control requirements.
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
Achieves a consistent and dimensionally stable bead deposition, improving print quality and throughput by minimizing variations in flow rate and temperature, allowing for the production of larger and more complex 3D printed components.
Implementation Method 1
a servo-controlled fixed-displacement pump and coordinated speed control between the extruder and polymer pump to synchronize speed changes, ensuring a consistent flow rate and bead size
Implementation Method 2
Friction from the rotating screw, combined with heat from the barrel softens the plastic
Implementation Method 3
The barrel may be heated. Thermoplastic material in the form of small pellets is introduced into one end of the rotating screw
Implementation Method 4
Implementing a servo-controlled fixed-displacement pump and coordinated speed control between the extruder and polymer pump to synchronize speed changes, ensuring a consistent flow rate and bead size
Data Source
AI summary
An additive manufacturing machine includes a first segment that is movable while the additive manufacturing machine deposits material, a second segment being configured to move relative to the first segment, and an extruder having a screw disposed within a barrel. The machine also includes a pump having an inlet and an outlet, a nozzle physically coupled to the second segment and configurable to: (i) translate along a first axis, along a second axis perpendicular to the first axis, and along a third axis and (ii) dispense the material, and a controller configured to control a speed of the screw of the extruder and a speed of the pump based on increases or decreases in movement of the nozzle along at least two axes of the first axis, the second axis, and the third axis, in operation during deposition of the material in an arc or corner.