Tool Bit Extension Adapter With Locking Collar and Dust Seal

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Solution Overview

Problem

Existing power tool adapters do not effectively secure tool bits during drilling operations and fail to prevent dust and debris from entering the adapter, limiting their functionality and durability.

Innovation Solution

An extension adapter with a body having a bore for receiving the tool bit, a moveable collar for securing the bit, and gaskets to inhibit dust and debris, allowing tool bits of various diameters to be securely attached and removed without tools, while maintaining axial and rotational stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a traditional extension adapter is used to extend tool bit reach, then drilling beyond bit length is enabled, but the adapter fails to securely secure the tool bit during operation and allows dust and debris to enter

Engineering Contradiction:
Improvedrilling reachVSAvoidtool bit security
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The collar is designed to be moveable between an unlocked position (for tool bit insertion) and a locked position (for securing during operation). This dynamic mechanism allows the adapter to transition from a loading state to a secure operational state, resolving the contradiction between ease of tool bit attachment and secure retention during drilling.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The collar acts as an intermediary locking mechanism between the tool bit and the adapter body. When moved to the locked position, it mediates the connection by engaging with the tool bit shank, providing secure retention while allowing the adapter to maintain its extended reach function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the adapter structure is opened for tool bit insertion, then tool bits can be easily attached and removed, but dust and debris can enter the adapter interior

Engineering Contradiction:
Improvetool bit attachmentVSAvoiddust and debris ingress
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A flexible gasket is positioned within the adapter body to seal the interior bore. This thin film barrier prevents dust and debris from entering the adapter interior while allowing the tool bit to be inserted and removed through the same opening. The gasket flexes to accommodate tool bit passage while maintaining the seal during operation.

Inventive Principle:
Principle #30Flexible shells and thin films

3Strength

If the adapter has a larger outer diameter for structural strength, then durability is improved, but the ratio of outer diameter to bore diameter becomes excessive

Engineering Contradiction:
Improveadapter durabilityVSAvoidadapter proportions
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The adapter body exhibits local quality variations with different diameters at different sections. The front portion has a larger diameter for strength and rigidity, the middle section has a reduced diameter for proportionality, and the rear portion has a flange for mounting. This localized variation in diameter allows the adapter to maintain structural strength where needed while keeping the overall outer diameter to bore diameter ratio within acceptable limits.

Inventive Principle:
Principle #3Local quality

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 adapter ensures secure attachment and removal of tool bits, prevents dust ingress, and allows for drilling beyond the bit's length, enhancing operational efficiency and durability.

Implementation Method 1

a spring configured to move the collar into the gasket to compress the gasket between the flange and a recess in the collar

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

compress the gasket between the flange and a recess in the collar to inhibit dust and debris from entering into the adapter

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4427888B1Power tool to tool bit extension adapter
Publication Date: 2026.02.04 MILWAUKEE ELECTRIC TOOL CORP
  • EP4427888B1 patent drawingFigure 1
  • EP4427888B1 patent drawingFigure 2
  • EP4427888B1 patent drawingFigure 3

AI summary

An extension adapter is configured to couple a tool bit to a power tool, the power tool being configured to drive the extension adapter and the tool bit about a rotational axis. The extension adapter comprises a body and a collar. The body includes an inner surface defining a bore configured to receive the tool bit, the bore including a first diameter. The collar is moveable between an unlocked position and a locked position, the unlocked position configured to allow the tool bit to be removed from the bore, and the locked position configured to secure the tool bit to the body. The extension adapter includes a maximum outer diameter. A ratio of the maximum outer diameter of the extension adapter over the first diameter of the bore is equal to or less than 2.5.