Tool Bit Holder With Segmented Jaws and Elastic Biasing

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Solution Overview

Problem

Existing tool bit holders fail to non-rotationally and axially retain tool bits of varying shank configurations efficiently, particularly those with polygonal cross-sections and annular grooves, while allowing for quick insertion and release.

Innovation Solution

A tool bit holder design featuring a holder body with a polygonal cross-sectional bore and annular groove, utilizing elastic bands and radially extending balls to securely engage and retain shanks of different sizes and configurations, ensuring non-rotational and axial retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional chuck with a single shank-receiving opening is used, then it can hold standard round shanks, but it cannot effectively retain polygonal shanks with annular grooves without slippage

Engineering Contradiction:
Improveretention reliabilityVSAvoidshank configuration compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The shank-receiving opening is divided into multiple segmented jaws (first jaw, second jaw, third jaw) that can independently move and adjust. Each jaw can be positioned to match different shank configurations (round, hexagonal, triangular, square) and engage with annular grooves separately, providing reliable retention for various shank types without slippage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The jaws are designed to be movable rather than fixed, allowing them to dynamically adjust their positions and orientations. The jaws can rotate about pivot points and move radially to engage different shank geometries, enabling the chuck to adapt to various shank configurations while maintaining secure retention through elastic biasing forces.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the chuck jaws are fixed in position, then the structure is simple, but it cannot accommodate multiple shank sizes and configurations

Engineering Contradiction:
Improveshank size and configuration accommodationVSAvoidchuck structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The chuck is designed with universal jaws that can perform multiple functions by adjusting their positions and orientations. The same set of jaws can retain round shanks, polygonal shanks, and shanks with annular grooves of various sizes, eliminating the need for multiple specialized chucks while managing structural complexity through modular jaw design.

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

Solution Approach 2:

The jaw structure employs a nested arrangement where multiple jaws are positioned concentrically around the shank-receiving opening. The jaws can be independently adjusted and nested within the chuck body, allowing compact storage of multiple jaw positions and configurations within a single chuck structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Adaptability or versatility

If elastic bands and movable jaws are used to accommodate various shanks, then versatility improves, but the device complexity increases

Engineering Contradiction:
Improveshank configuration adaptabilityVSAvoidjaw mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The jaw mechanism utilizes elastic bands to provide biasing forces that can be adjusted to match different shank sizes and geometries. By changing the elastic properties and pre-tension of the bands, the system adapts to various shank configurations without requiring complex mechanical adjustment mechanisms, managing complexity through parameter variation rather than structural complexity.

Inventive Principle:
Principle #35Parameter changes

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 quick and secure insertion and release of tool bits, maintaining rotational motion transmission without relative movement, accommodating multiple shank sizes and configurations within the same holder.

Implementation Method 1

an annular groove receives an elastic band that is biased radially inwardly a plurality of balls that extend radially into the bore

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2979790B1Tool bit holder for power tool
Publication Date: 2017.06.14 BLACK & DECKER CORP
  • EP2979790B1 patent drawingFigure 1
  • EP2979790B1 patent drawingFigure 2~4
  • EP2979790B1 patent drawingFigure 5

AI summary

A tool bit holder releasably retains a shank of a tool bit having three flat faces arranged generally in a triangle and an annular groove. A holder body has a shank-receiving bore bounded by an inner wall with three flat inner wall surfaces arranged generally in a triangle. A plurality of windows, defined in the inner wall, extend radially outward from the bore. A plurality of retaining members is received in the plurality of windows and extends at least partially through the window into the bore. An elastic band around the retaining members biases the retaining members radially inward toward the bore. The flat wall portions are configured to engage the flat faces of the tool bit to non-rotationally retain the shank in the tool holder and the retaining members are configured to engage the annular groove to axially retain the tool bit in the tool holder.