Fiber Placement Head Wrist with Multi-Stage Twist Delivery
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Solution Overview
Problem
Existing fiber placement machines have limited dexterity due to the offset of the fiber band from the centers of rotation of the wrist axes, causing the fibers to orbit rather than twist, which restricts the range of orientation and makes it difficult to lay fibers on highly contoured surfaces.
Innovation Solution
A fiber delivery system that twists the fiber band at least three times between a fixed forearm redirect roller and a compaction roller, providing enhanced yaw, pitch, and roll movements to improve dexterity, allowing for precise orientation and separation of fibers on complex surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fiber band is offset from the centers of rotation of the wrist axes to accommodate the end effector width, then the end effector can be positioned correctly, but the fiber band orbits the center of rotation instead of merely twisting, increasing deviation from perpendicularity and limiting wrist orientation range
Solution Approach 1:
The fiber delivery system is segmented into multiple independent redirect rollers positioned at different locations. Instead of a single offset path, the fiber band is redirected through multiple discrete points (rollers 29, 30a, 30b, 30c) that collectively guide the fiber while reducing orbital motion. This segmentation allows the fiber to follow a more controlled path that minimizes deviation from perpendicularity to the rotation axes.
Solution Approach 2:
Redirect rollers serve as intermediary elements between the fiber band and the wrist axes. These rollers mediate the interaction by providing controlled contact points that redirect the fiber band's path. The rollers act as intermediaries that convert the problematic orbital motion into more controlled twisting motion, reducing the harmful side angles while maintaining proper end effector positioning.
2Ease of operation
If redirect rollers are mounted on stationary brackets to provide fiber redirection, then the fiber band can be redirected, but all three degrees of freedom must be accommodated by the relative position of rollers, limiting the range through which the wrist can be oriented
Solution Approach 1:
The system transitions from static redirect rollers to dynamic, controllable redirect mechanisms. Servo-motors are integrated with the redirect roller assemblies to provide active control of roller positions and orientations. This allows the system to dynamically adjust the fiber path in real-time as the wrist moves through its range of motion, accommodating all three degrees of freedom without limiting the wrist's orientation capability.
Solution Approach 2:
The redirect roller assemblies incorporate feedback control through servo-motors that respond to wrist position and orientation data. This feedback mechanism allows the system to continuously adjust the redirect roller positions to maintain optimal fiber alignment regardless of wrist orientation, thereby expanding the usable range of motion while maintaining precise fiber control.
3Adaptability or versatility
If the fiber band is twisted multiple times between redirect rollers, then dexterity is improved and fiber separation is maintained, but the system complexity increases with additional rollers and control mechanisms
Solution Approach 1:
The redirect roller assemblies are designed as multi-functional units that combine fiber redirection, fiber separation, and active control capabilities in single integrated packages. Each roller assembly serves multiple purposes: redirecting the fiber band, maintaining separation between tows, and providing controlled twisting motion. This multi-functionality reduces the need for separate components and simplifies the overall system architecture despite the multiple twisting actions required.
Data Source
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AI summary
A fiber placement machine has a creel that supplies a fiber band to a presser member that applies the fiber band to a tool or form. The presser member is part of a head that is attached to the creel of the machine by a wrist that provides movement about yaw, pitch and roll axes with respect to the creel. The fiber band is supplied by a fiber band delivery system that is associated with the wrist and that is characterized by a capability to twist the fiber band in two stages about the yaw axis or the roll axis.