Additive Manufacturing Material Dispensing With Servo Pump Feedback
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Solution Overview
Problem
Existing 3D printing methods using molten thermoplastic materials face challenges in producing consistent bead sizes due to variations in extruder speed and heat generation, leading to inconsistent print quality, especially when the print head moves at variable speeds.
Innovation Solution
Implementing a servo-controlled fixed-displacement pump and coordinating the speed of the extruder with the polymer pump to ensure simultaneous and proportional speed changes, using algorithms to synchronize the extruder and pump operations based on pressure and nozzle translation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the extruder operates at variable speeds to match nozzle movement, then the print head can move at variable speeds for complex geometries, but the bead size becomes inconsistent due to variations in extrusion rate and heat generation
Solution Approach 1:
The system uses a pressure sensor to monitor extrusion pressure in real-time and feeds this information back to the controller. The controller adjusts the extruder motor speed dynamically based on the pressure feedback, creating a closed-loop control system that maintains consistent bead size despite variable nozzle movement speeds.
Solution Approach 2:
The extruder system transitions from static operation to dynamic control, where the extruder motor speed is continuously adjusted in real-time based on pressure feedback and desired bead size. This dynamic adjustment allows the system to adapt to varying nozzle speeds while maintaining consistent material deposition.
2Productivity
If the extruder speed is increased to improve productivity, then more material can be deposited faster, but heat generation increases causing inconsistent material flow and bead size
Solution Approach 1:
The pressure sensor provides real-time feedback on extrusion pressure, allowing the controller to detect when heat generation is causing material flow inconsistencies. The system adjusts extruder speed dynamically to compensate for thermal effects, maintaining both high productivity and precise bead size control.
Solution Approach 2:
The system changes the operating parameters of the extruder dynamically by adjusting motor speed based on real-time pressure feedback and thermal conditions. This allows the system to optimize both deposition rate and bead size consistency by adapting parameters to current operational conditions.
3Device complexity
If a simple extruder system is used, then the device complexity is low, but the ability to maintain consistent bead size at variable speeds is insufficient
Solution Approach 1:
The system adds a pressure sensor and feedback control mechanism to the extruder, transforming it from an open-loop to a closed-loop system. This feedback mechanism enables the system to automatically compensate for variations in bead size caused by speed changes, maintaining precision without requiring complex mechanical adjustments.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with an electronic control system that uses pressure feedback to regulate extruder speed. This substitution of mechanical complexity with electronic control achieves precise bead size consistency while keeping the overall device structure relatively simple.
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 stable flow rate of molten material, ensuring uniform bead deposition and improved print quality by compensating for variations in extruder speed and heat, thereby enhancing the manufacturing of larger items or larger quantities.
Implementation Method 1
Friction from the rotating screw, combined with heat from the barrel softens the plastic
Implementation Method 2
heat from the barrel softens the plastic
Implementation Method 3
sensing a pressure of the flowable material
Implementation Method 4
applying this material in layers to produce a final part
Implementation Method 5
Friction from the rotating screw, combined with heat from the barrel softens the plastic
Data Source
AI summary
An additive manufacturing method for delivering a flowable material from a nozzle of a programmable computer numeric control (CNC) machine, the nozzle being configured to translate along a first axis, a second axis perpendicular to the first axis, and a third axis orthogonal to the first and second axes. In one embodiment, the method includes actuating an extruder to form a flowable material, delivering the flowable material to a pump, sensing a pressure of the flowable material, and adjusting at least one of a speed of the extruder and a speed of the pump based on at least one of the sensed pressure and a rate of translation of the nozzle along one or more of the first, second, and third axes.