Stepped Chuck Assembly for Fast Multi-Size Bit Changes
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Solution Overview
Problem
Existing chuck assemblies for rotary power tools either lack the ability to accommodate multiple standard sized bit shanks efficiently or suffer from the disadvantages of continuously variable chucks, such as increased weight, size, manufacturing cost, and time required to change bits.
Innovation Solution
A chuck assembly design that includes a body with a plurality of openings and threads, jaws received within these openings, a collar with a stepped portion to engage the jaws, and a spring biasing the collar to ensure secure engagement with bit shanks of various standard sizes without the drawbacks of continuously variable chucks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuously variable chuck is used to accommodate multiple bit sizes, then adaptability is improved, but weight, size, and manufacturing cost increase
Solution Approach 1:
The chuck is segmented into a body and a collar that can rotate independently. The collar with stepped portions provides different engagement positions for jaws to accommodate multiple bit sizes, while the body remains fixed and optimized for a specific size. This segmentation allows the chuck to achieve multi-size adaptability without requiring the entire chuck structure to be continuously variable, thereby reducing weight.
Solution Approach 2:
The collar is designed to rotate relative to the body, dynamically changing the engagement position of the jaws. This dynamic adjustment mechanism allows the same physical chuck structure to adapt to different bit sizes through rotation, rather than requiring multiple fixed-size chucks or a complex continuously variable mechanism, thus reducing overall weight and complexity.
2Adaptability or versatility
If a continuously variable chuck is used to accommodate multiple bit sizes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The chuck is divided into a body and a collar, where the body provides the fixed structural foundation optimized for a specific bit size, and the collar provides the adjustable engagement mechanism. This segmentation simplifies the overall design by separating the fixed and variable functions into distinct components, reducing device complexity compared to a continuously variable chuck.
Solution Approach 2:
The rotating collar provides a simple dynamic mechanism to switch between different engagement positions for multiple bit sizes. This rotational adjustment is mechanically simpler than the complex continuously variable mechanisms used in traditional variable chucks, reducing device complexity while maintaining multi-size adaptability.
3Ease of manufacture
If a standard size-specific chuck is used, then manufacturing cost and weight are reduced, but adaptability to multiple bit sizes deteriorates
Solution Approach 1:
The chuck is designed with universal adaptability through the collar's stepped portions that can engage with jaws at different positions to accommodate multiple standard bit sizes (e.g., 1/4-inch, 3/8-inch, 7/16-inch). This multi-functionality allows a single chuck design to replace multiple size-specific chucks, achieving adaptability without significantly increasing manufacturing cost.
Solution Approach 2:
The rotating collar mechanism provides a simple dynamic adjustment capability that enables the same physical chuck to adapt to different bit sizes. This dynamic feature is achieved through straightforward mechanical design with minimal additional manufacturing complexity, allowing cost-effective multi-size accommodation.
4Adaptability or versatility
If a continuously variable chuck is used, then adaptability is improved, but time to change bits increases
Solution Approach 1:
The rotating collar provides a quick dynamic adjustment mechanism that allows the user to switch between different engagement positions for multiple bit sizes by simply rotating the collar. This is much faster than the continuous adjustment required by traditionally variable chucks, reducing the time to change bits while maintaining adaptability.
Solution Approach 2:
The collar is pre-configured with discrete stepped portions at specific positions corresponding to standard bit sizes. This preliminary arrangement of engagement positions allows for rapid selection and adjustment to the correct size without requiring continuous adjustment or measurement, thereby reducing bit change time while maintaining adaptability to multiple sizes.
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 chuck assembly effectively secures tool bits of multiple standard sizes with improved efficiency, reducing weight, size, and manufacturing costs while minimizing the time required to change bits.
Implementation Method 1
a spring biasing the collar such that the stepped portion is biased into engagement with the plurality of jaws
Data Source
AI summary
A chuck assembly for a rotary power tool includes a body rotatable about a central axis, the body including a plurality of openings and a first set of threads, a plurality of jaws received within the plurality of openings in the body; a collar surrounding the body, the collar including a stepped portion configured to engage the plurality of jaws to limit radial movement of the plurality of jaws, a second set of threads coupled for co-rotation with the collar and engageable with the first set of threads on the body such that rotation of the collar relative to the body causes the collar to move axially along the body, and a spring biasing the collar such that the stepped portion is biased into engagement with the plurality of jaws.