Multi-Size Chuck Assembly With Segmented Thread Engagement

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Solution Overview

Problem

Existing chuck assemblies for rotary power tools either suffer from the disadvantages of continuously variable chucks or are optimized for a single standard hex-shanked bit size, failing to efficiently accommodate multiple standard bit shank sizes.

Innovation Solution

A chuck assembly design featuring a ring and collar system with axial movement and co-rotation, incorporating detents and arcuate grooves for tactile feedback, and a mechanism that allows engagement with multiple thread segments on the chuck body to securely hold different nominal-sized bit shanks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a chuck assembly is optimized for a single standard hex-shanked bit size, then weight, size, and manufacturing cost are reduced, but the ability to accommodate multiple bit sizes is limited

Engineering Contradiction:
Improveability to accommodate multiple bit sizesVSAvoidchuck assembly structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The chuck body is segmented with multiple distinct thread segments (first, second, and third thread segments) that correspond to different bit sizes. Each thread segment can selectively engage with the collar to accommodate 1/4-inch, 3/8-inch, and 7/16-inch hex bits respectively. This segmentation allows the single chuck assembly to handle multiple bit sizes without requiring complete structural redesign.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The chuck assembly is designed with multi-functionality to accept multiple standard hex-shanked bit sizes (1/4-inch, 3/8-inch, and 7/16-inch) through a single device. The universal design incorporates multiple thread segments and adjustable jaws that can adapt to different bit diameters, eliminating the need for multiple specialized chucks while maintaining optimized performance for each size.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a continuously variable chuck is used to accept a continuous range of bit sizes, then versatility is improved, but weight, size, and manufacturing cost increase

Engineering Contradiction:
Improverange of bit sizes acceptedVSAvoidchuck assembly weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

Instead of implementing a continuously variable adjustment mechanism which would add weight and complexity, the invention segments the adjustment into discrete standard sizes. The chuck body contains specific thread segments for 1/4-inch, 3/8-inch, and 7/16-inch bits, allowing versatile accommodation of common bit sizes while maintaining a lightweight and compact structure similar to fixed-size chucks.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If multiple thread segments are incorporated on the chuck body, then the ability to secure different nominal-sized bits is improved, but the device complexity increases

Engineering Contradiction:
Improveselection of bit sizesVSAvoidthread segments and collar mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple functional elements are merged into the collar component: it contains internal threads that engage with multiple different thread segments on the chuck body, incorporates a spring mechanism for jaw actuation, and includes a detent system for positioning. This merging allows complex multi-size functionality to be achieved through a single integrated component rather than multiple separate mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The jaw positioning system is made dynamic through the spring-loaded collar mechanism. When the collar is rotated, the spring expands or contracts to move the jaws radially inward or outward, allowing the same jaw structure to accommodate different bit sizes dynamically. This dynamic adjustment simplifies the overall structure compared to having fixed positioning mechanisms for each size.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3520937B1Chuck assembly for a rotary power tool
Publication Date: 2024.05.08 MILWAUKEE ELECTRIC TOOL CORP
  • EP3520937B1 patent drawingFigure 1
  • EP3520937B1 patent drawingFigure 2
  • EP3520937B1 patent drawingFigure 3

AI summary

A chuck assembly (10) for a rotary power tool includes a chuck body (34) rotatable about a central axis (50). The chuck body (34) has a plurality of slots (62), each oriented at an oblique angle relative to the central axis (50). The chuck assembly (10) also includes a plurality of jaws (38), each movable along a respective one of the slots (62). The chuck assembly also includes a collar (42) coupled to the plurality of jaws (38). The collar (42) is selectively engageable with the chuck body (34) such that, when engaged, the plurality of jaws (38) are movable along the plurality of slots (62) in response to rotation of the collar (42).