Extruder-Pump Speed Coordination for Consistent 3D Print Beads
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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 the print head moves at variable speeds.
Innovation Solution
Implementing a servo-controlled fixed-displacement pump and coordinated speed adjustments between the extruder screw and polymer pump to synchronize speed changes, ensuring a consistent flow rate and bead size regardless of melt temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a traditional extruder with variable speed screw is used to accommodate print head speed variations, then the system can handle variable printing speeds, but the extrusion rate becomes inconsistent leading to variable bead size and poor print quality
Solution Approach 1:
The system dynamically adjusts the speed ratio between the screw and pump through servo control, allowing both components to vary their speeds in coordination. This dynamic speed coordination ensures that the extruder screw and pump maintain synchronized operation even when print head speed changes, preventing bead size inconsistency while accommodating variable printing speeds.
Solution Approach 2:
The servo control system continuously monitors and adjusts the speeds of both the screw and pump based on real-time conditions. This feedback mechanism ensures that speed variations are coordinated between the extrusion components, maintaining consistent material flow and bead size despite changes in print head velocity.
2Speed
If the screw speed is varied to match print head speed, then variable printing speeds are accommodated, but heat energy generation varies causing inconsistent melt temperature and extrusion rate
Solution Approach 1:
The system uses dynamic speed coordination where the screw and pump speeds are independently controlled but synchronized through servo feedback. This allows the screw to maintain more consistent rotational speed for stable heat generation, while the pump compensates for speed variations to maintain consistent extrusion rate, resolving the temperature inconsistency problem.
Solution Approach 2:
The pump acts as an intermediary between the screw and the deposition point. It receives material from the screw at variable speeds and compensates by adjusting its own speed to deliver material at a consistent rate. This intermediary function isolates the screw's heat generation from the final extrusion rate, maintaining both temperature consistency and flow stability.
3Stability of the object's composition
If breaker plates and screens are used to control pressure and mix material, then material mixing and pressure control improve, but device complexity and mechanical constraints increase
Solution Approach 1:
The system replaces the mechanical mixing and pressure control functions of breaker plates and screens with a servo-controlled pump. The pump uses precision speed control to achieve material homogenization and pressure regulation without requiring complex mechanical structures, thereby reducing device complexity while maintaining or improving material consistency.
Solution Approach 2:
Instead of using physical barriers like breaker plates and screens, the system changes the operational parameters of the pump (speed, flow rate) to achieve the same effects. By controlling the pump's rotational speed and displacement, the system can regulate pressure and promote material mixing through dynamic flow control rather than static mechanical structures.
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 stable and consistent deposition of thermoplastic material, improving print quality and reducing mechanical complexity by eliminating the need for breaker plates and screens, while accommodating different materials with adjustable pressure settings.
Implementation Method 1
a pump (e.g., a servo-controlled fixed-displacement pump, such as, e.g., a gear pump) having an inlet and an outlet
Implementation Method 2
a heated nozzle, which melts the thermoplastic material and applies it to the structure being printed
Implementation Method 3
an extruder having an outlet and including a screw disposed within a barrel
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.