Collet Bit Retainer for Low-Runout Multi-Shank Tool Holding
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Solution Overview
Problem
Existing bit retainers for power tools face challenges with runout and compatibility across different shank geometries, with quick-release retainers offering reduced runout but limited to single shank sizes and three-jaw chucks being cumbersome and time-consuming to change.
Innovation Solution
A bit retainer design featuring a collet with multiple jaws and a movable sleeve that compresses around the tool bit, allowing for reduced runout and quick-change functionality while accommodating both hexagonal and round shank bits, and being interchangeable with standard collets of various sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a three-jaw chuck is used to retain tool bits, then compatibility with different shank geometries is achieved, but the device becomes heavy, long, and time-consuming to change bits
Solution Approach 1:
The bit retainer is segmented into a body portion and a separate collet assembly that can be independently removed and replaced. This allows the main body to remain compact while the collet provides the adaptability for different bit geometries through its multiple jaws that can be adjusted or swapped.
Solution Approach 2:
The collet is designed with multiple jaws that can accommodate various shank geometries including hexagonal, square, and round bits. This universal gripping mechanism allows a single compact retainer design to serve multiple functions across different bit types without requiring the entire retainer assembly to be large or heavy.
2Productivity
If a quick-release bit retainer is used, then bit swapping efficiency is improved, but the device is limited to single shank size and has greater runout
Solution Approach 1:
The collet incorporates a dynamic adjustment mechanism with multiple jaws that can be quickly opened and closed via a actuating lever. This allows rapid bit insertion and removal while maintaining precise concentricity during operation, reducing runout compared to fixed quick-release mechanisms.
Solution Approach 2:
The collet acts as an intermediary between the compact retainer body and the tool bit. It provides a precision-gripping interface that minimizes runout while allowing quick release functionality through the actuating mechanism, effectively mediating between the requirements for speed and precision.
3Adaptability or versatility
If a collet with multiple jaws is used, then compatibility with various bit sizes is achieved, but the device length increases
Solution Approach 1:
The collet jaws are nested within the retainer body when in the closed position, allowing multiple jaw structures to occupy minimal axial space. The jaws can be quickly opened outward for bit insertion, providing multi-size compatibility without extending the overall device length during normal operation.
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
The solution achieves an approximately 80% reduction in runout compared to conventional quick-change bit retainers and allows for a wider range of bit compatibility without increasing tool length, maintaining quick-change functionality.
Implementation Method 1
a wedge surface engageable with the collet, and a sleeve surrounding the body. The sleeve is movable relative to the body to engage the wedge surface against the collet and compress the plurality of jaws around the tool bit
Data Source
AI summary
A bit retainer is configured to couple a tool bit to an output spindle of a power tool. The bit retainer includes a body coupled for co-rotation with the output spindle about a rotational axis, a collet including a plurality of jaws positioned at least partially within the body, the collet defining a bore between the plurality of jaws configured to receive the tool bit, a wedge surface engageable with the collet, and a sleeve surrounding the body. The sleeve is movable relative to the body to engage the wedge surface against the collet and compress the plurality of jaws around the tool bit.