Retractable Collet Assembly for Welding Fasteners in Recesses
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Solution Overview
Problem
Current fastener feeding systems for resistance welding lack an efficient mechanism to feed and install fasteners in multiple axes, particularly in recesses or counterbores of work pieces, especially when there is no side access due to the work piece geometry.
Innovation Solution
A collet assembly with an actuator and movable collet fingers that grip and release fasteners, allowing the electrode to engage and weld them to an external work piece, featuring a pneumatic system for controlled movement and a sensor for alignment, enabling the collet to retract and expose the electrode for welding while maintaining grip on the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional spot welding system is used, then simple welding of accessible areas is achieved, but fasteners cannot be installed in recessed areas without side access
Solution Approach 1:
The patent introduces a multi-axis robotic system that moves beyond conventional single-axis or two-axis welding positions. The robotic arm provides three-dimensional positioning capability, allowing the electrode to reach into recessed areas and counterbores from multiple angles and depths, enabling fastener installation in geometries previously inaccessible to welding equipment
Solution Approach 2:
The patent employs a specialized fastener feeding system with a collet assembly that acts as an intermediary between the robotic electrode and the fastener. This intermediary mechanism precisely feeds, positions, and releases fasteners at the electrode tip, enabling the robotic system to handle small fasteners reliably in difficult-to-reach locations
2Ease of operation
If the collet remains advanced to grip the fastener, then fastener holding is maintained, but the electrode cannot engage the fastener for welding
Solution Approach 1:
The collet assembly incorporates a dynamic actuation mechanism that allows the collet fingers to move between extended and retracted positions. Pneumatic or hydraulic actuators control the collet's movement, enabling it to extend for reliable fastener gripping during feeding, then retract to allow electrode engagement and welding without compromising fastener holding reliability at either stage
Solution Approach 2:
The system employs periodic cycling of the collet actuator to rhythmically extend and retract the collet during the fastening process. This periodic action coordinates with the welding cycle timing, ensuring the collet is extended for fastener capture, retracts for electrode contact and welding, then returns to extended position for the next fastener, maintaining operational reliability through consistent cyclic motion
3Adaptability or versatility
If the electrode length varies, then flexibility in electrode selection is achieved, but alignment precision with the fastener is compromised
Solution Approach 1:
The robotic positioning system incorporates feedback control through sensors that detect the actual position of the electrode tip relative to the fastener. The control system uses this feedback to dynamically adjust the robotic arm's position and orientation in real-time, compensating for variations in electrode length and ensuring precise alignment and consistent weld quality regardless of electrode specifications
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
Enables efficient installation and welding of fasteners in recessed areas without side access, ensuring reliable fastening and minimizing electrode wear, with the collet's design allowing for automatic compensation of electrode tip dressing and maintaining alignment independent of electrode length.
Implementation Method 1
The actuator includes a cap with an advance port in communication with the central passage of the housing for providing pneumatic air pressure for advancing the collet to its advanced position, and a return port in communication with the central passage of the housing for providing pneumatic air pressure for retracting the collet to its retracted position
Data Source
AI summary
A collet assembly including an actuator and a collet connected to the actuator. The collet assembly is adapted to be installed on a welding electrode holder having an electrode. The collet is moveable by the actuator from an advanced position, in which the collet is adapted to grip a fastener such as a welding rivet, and a retracted position, in which at least a portion of the collet is retracted into the actuator to enable the electrode to engage the fastener for welding to a work piece, and the collet is adapted to release the fastener.