Rotary Tool Mandrel Locking Geometry for Faster Accessory Changes
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Solution Overview
Problem
Rotary tools lack an efficient mechanism for quickly and securely coupling and decoupling accessories, leading to cumbersome and time-consuming operations.
Innovation Solution
A mandrel design featuring a shaft with radial locking projections and a collar with angularly offset coupling projections, along with a nut that threads onto the shaft, allowing for easy attachment and detachment of accessories by aligning and rotating the accessory's mating interface to match the mandrel's profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional coupling mechanisms are used, then accessories can be securely attached to the rotary tool, but the coupling and decoupling operations become time-consuming and cumbersome
Solution Approach 1:
The coupling mechanism is segmented into distinct functional components: locking projections on the shaft for secure attachment, coupling projections on the collar for interface engagement, and a nut for actuating the coupling/decoupling action. This segmentation allows each component to perform its specific function efficiently, enabling quick accessory changes while maintaining secure attachment.
2Productivity
If a simple coupling mechanism is used, then accessory changes are quick and easy, but the security and reliability of the attachment may be compromised
Solution Approach 1:
The locking projections are pre-positioned on the shaft and the coupling projections are pre-positioned on the collar in specific angular relationships. When the accessory is inserted and the nut is tightened, these pre-positioned features automatically engage in the correct configuration, ensuring secure attachment without requiring complex alignment procedures or multiple steps.
Solution Approach 2:
The locking projections and coupling projections utilize curved or angled surfaces that provide mechanical advantage and self-centering during the coupling process. The curved profiles allow the components to guide each other into proper alignment and maintain secure engagement through the tightening action of the nut.
3Reliability
If multiple components are added to improve coupling security, then attachment reliability increases, but the device complexity increases
Solution Approach 1:
The locking and coupling functions are merged into a single integrated mechanism where the locking projections and coupling projections work together through the action of a single nut. This consolidation achieves reliable secure attachment without requiring separate locking devices, alignment mechanisms, or multiple fastening components, thereby maintaining simplicity.
Data Source
AI summary
A rotary tool mandrel includes a shaft, locking projections, a collar, and a fastener. The shaft extends along a longitudinal axis and includes a distal end. The locking projections protrude radially relative to the longitudinal axis and positioned on opposite sides of the longitudinal axis from one another. Each of the locking projections define a locking projection outer profile that is rectilinear. The collar is coupled to the shaft and includes a pair of coupling projections protruding from a surface of the collar adjacent the distal end of the shaft. The coupling projections are angularly offset from the locking projections with respect to the longitudinal axis. Each of the coupling projections define a coupling projection that is rectilinear. The fastener is coupled to the shaft and movable relative to the shaft along the longitudinal axis, and movement of the fastener causes the locking projections to move toward the coupling projections.