Force-Regulated Additive Manufacturing with Upstroke Feedback
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Solution Overview
Problem
Existing additive manufacturing techniques, particularly bottom-up stereolithography, lack efficient methods for industrial use, require manual tuning of velocity and acceleration, and are prone to damage from foreign objects and overloading, especially when producing objects with unvented cavities or flexible materials.
Innovation Solution
An apparatus and method utilizing an elevator assembly, force sensors, and a controller to regulate the speed and acceleration of the upstroke based on sensed force, and detect foreign objects using multiple force sensors to prevent collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual tuning of velocity and acceleration is used in bottom-up stereolithography, then the process can be operated, but it requires significant operator intervention and time for optimization
Solution Approach 1:
The patent implements force feedback control by measuring the force exerted on the build platform during reciprocation and using this information to automatically adjust velocity and acceleration parameters. The controller modifies the upstroke speed based on sensed force to maintain a predetermined target force, eliminating the need for manual trial-and-error tuning while optimizing the refilling process.
Solution Approach 2:
The system performs self-optimization by automatically adjusting its own operating parameters based on real-time force measurements. The controller autonomously modifies velocity and acceleration without external intervention, allowing the system to self-regulate and adapt to different printing conditions, thereby reducing operator burden and time investment.
2Productivity
If high speed reciprocation is used to speed up refilling, then productivity increases, but the risk of damage from foreign objects and overloading increases
Solution Approach 1:
Force sensors continuously monitor the force applied during reciprocation and provide real-time feedback to the controller. When foreign objects or overloading conditions are detected (abnormal force levels), the system automatically adjusts speed and acceleration to prevent damage, enabling high-speed operation with built-in safety protection.
Solution Approach 2:
The system prepares for potential harmful events by implementing force-based monitoring and control before damage occurs. The force sensors detect abnormal conditions early in the reciprocation cycle, allowing the controller to preemptively adjust parameters to avoid collisions or overloading, thus cushioning against potential damage.
3Manufacturing precision
If force feedback control is implemented to optimize refilling, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent integrates force feedback control to precisely regulate the refilling of the build region. Force sensors measure the force during reciprocation, and the controller uses this information to adjust velocity and acceleration, ensuring optimal refilling precision. This automated control eliminates manual tuning while maintaining high manufacturing precision.
Solution Approach 2:
The system replaces manual mechanical adjustment with automated force-based control. Instead of operators physically tuning velocity and acceleration parameters, the controller automatically modifies these parameters based on force sensor feedback, substituting mechanical intuition with precise electronic control and sensing.
4Reliability
If multiple force sensors are used to detect foreign objects, then reliability improves, but device complexity increases
Solution Approach 1:
The patent divides the detection function across multiple force sensors positioned at different locations on the build platform. Each sensor independently monitors force in its local region, and the controller compares readings between sensors to detect foreign objects. This segmented approach improves detection reliability by providing multiple independent measurement points.
Solution Approach 2:
The force sensors serve multiple functions: they monitor refilling force for precision control, detect foreign objects through comparative analysis, and prevent overloading. This multi-functionality allows the system to achieve high reliability across multiple operational aspects without proportionally increasing complexity, as the same sensors perform multiple detection and control tasks.
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
Reduces the need for manual tuning, minimizes damage to the apparatus and objects, and effectively prevents collisions with foreign objects during production.
Implementation Method 1
a light source configured to irradiate the build region through the window to form a solid polymer from the polymerizable liquid
Data Source
AI summary
A method of forming a three-dimensional object (31) includes the steps of: (a) providing an apparatus including a carrier (15), a light transmissive window (12) having a build surface, polymerizable liquid (21) on the build surface, and a growing object (31) on the carrier, the growing object produced by light polymerization of the polymerizable liquid; (b) vertically reciprocating the carrier (15) with respect to the build surface in an upstroke and a downstroke, the downstroke being shorter than the upstroke, to form a build region between the growing object and the build surface, and to fill the build region with the polymerizable liquid, while also: (i) sensing force exerted between the carrier and the build surface through the growing object (31) and the polymerizable liquid (21) during the upstroke; and (ii) modifying the speed, acceleration, or both speed and acceleration of the upstroke in response to the sensed force so that the sensed force approaches a predetermined target force; then (c) irradiating the build region with light through the light transmissive window to form a new portion of the object from the polymerizable liquid on the growing object; and then (d) repeating steps (b) through (c) to form additional portions on the growing object until the three-dimensional object is formed.