Cutting Tool Coupling with Axially Offset Threads

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Solution Overview

Problem

Existing cutting tools with threaded couplings often require additional fastening members like locknuts or screws, and struggle with accurate repeatable rotational positioning and torque opposition during metal cutting operations.

Innovation Solution

A cutting tool design featuring first and second components with axially offset helical coupling threads and radial stop surfaces, allowing for a differential tool coupling without additional fastening members, enabling quick-change assembly and precise rotational positioning, and opposing torque with radial stop surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If traditional threaded couplings are used, then the coupling is secure, but additional fastening members like locknuts or screws are required

Engineering Contradiction:
Improvenumber of fastening membersVSAvoidcoupling security
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent combines multiple coupling threads (first peripheral, first central, second peripheral, second central threads) with different pitches into a single integrated coupling system. This merging eliminates the need for separate fastening members like locknuts or screws, as the differential thread pitches inherently create the locking mechanism through their interaction during rotation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupling system is self-securing through the differential action of threads with different pitches. As the components rotate during assembly, the varying pitch rates cause the threads to self-align and lock together without requiring external fastening members. The system serves its own fastening function through the inherent mechanical interaction of the offset threads.

Inventive Principle:
Principle #25Self-service

2Productivity

If traditional threaded couplings are used, then the coupling is secure, but the assembly process is time-consuming

Engineering Contradiction:
Improveassembly speedVSAvoidcoupling security
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The coupling threads are pre-configured with specific pitch differences and axial offsets during manufacturing. This preliminary setup ensures that when the components are brought together and rotated, the threads automatically engage in the correct sequence and orientation, enabling quick-change assembly without requiring complex alignment procedures or multiple fastening steps.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The coupling system utilizes dynamic rotation during assembly to transform the static thread geometry into active engagement. The differential pitch causes the threads to progressively engage as rotation occurs, allowing the coupling to be secured quickly through a simple rotational motion rather than requiring multiple fastening operations.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If standard threaded couplings are used, then the components are coupled, but accurate repeatable rotational positioning is not achieved

Engineering Contradiction:
Improverotational positioning accuracyVSAvoidcoupling structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs asymmetric thread pitch values between the first and second components (different pitch rates) to create a unique engagement position. This asymmetry ensures that the threads can only fully engage at a specific rotational orientation, providing accurate and repeatable positioning. The radial stop surfaces further enforce this precise orientation by providing a definitive stop at the correct rotational position.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent replaces complex mechanical positioning systems (such as indexing mechanisms or alignment features) with a simplified thread pitch differential system. The mathematical relationship between the different pitch rates inherently determines the rotational position, eliminating the need for additional positioning mechanisms while achieving high precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Force

If radial stop surfaces are added to oppose torque, then torque resistance is improved, but the coupling structure becomes more complex

Engineering Contradiction:
Improvetorque oppositionVSAvoidcoupling structure
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The radial stop surfaces serve multiple functions: they provide torque opposition during cutting operations, define the final rotational position of the coupling, and act as a physical barrier to prevent over-rotation. By integrating these stop surfaces into the existing thread structure, the patent achieves multi-functionality without adding separate torque-resisting components.

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

Data Source

PatentEP2991790B1Cutting tool having a tool coupling with axially offset peripheral and central coupling threads and method of assembly thereof
Publication Date: 2020.03.04 ISCAR LTD
  • EP2991790B1 patent drawingFigure 1~2
  • EP2991790B1 patent drawingFigure 3~6
  • EP2991790B1 patent drawingFigure 7~9

AI summary

A cutting tool (20) includes first and second components (22,24), configured for differential coupling with each other. The first and second components (22,24) each include peripheral and central coupling threads (32,34;36,38) which each extend in a helical direction about a component axis (A,B) of the respective component (22,24). Each component's (A,B) peripheral and central coupling threads (32,34;36,38) are axially offset with respect to each other. The first and second components (22,24) each include a radial stop surface (40,42) located at the respective peripheral coupling thread (32,36). In an assembled position of the cutting tool (20), the radial stop surfaces (40,42) abut each other and the peripheral and central coupling threads (32,34) of the first component (22) threadingly engage the peripheral and central coupling threads (36,38) of the second component (24), respectively, forming a differential tool coupling between the first and second components (22,24).