Tapered Collet Tool Holder for Stable Side-Lock Fixation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional tool holders fail to provide stable fixation for cutting tools, especially in high-speed and high-precision machining applications due to large tolerances in the side lock recesses of cutting tools, leading to movement during operation.

Innovation Solution

A tool holder design featuring a holder body with a tapered collet and side lock bolts, along with a keyway and flat portions, that securely engages with an additionally machined cutting tool to reduce axial and depth tolerances to very small values, ensuring stable grip through multiple points of contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional tool holders with standard collets are used, then the structure is simple and easy to manufacture, but the cutting tool cannot be held stably during high-speed machining due to large tolerances in the side lock recess

Engineering Contradiction:
Improvestability of cutting tool holdingVSAvoidcomplexity of tool holder structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The tool holder is divided into multiple functional components: a collet for gripping the tool shank, side lock bolts for preventing axial movement, a key for rotational locking, and a holder body with precisely machined holes and recesses. Each component performs a specific function to collectively achieve stable tool holding.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The side lock recesses and keyway are additionally machined with very small tolerances in specific locations where precision is critical for stable tool holding. The collet also has precisely controlled outer diameter tolerances in the gripping region to ensure accurate engagement with the tool shank.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If additionally machined side lock recesses with very small tolerances are provided in the cutting tool, then axial movement is prevented, but the manufacturing complexity and cost increase

Engineering Contradiction:
Improvetolerance of side lock recessVSAvoidease of cutting tool manufacturing
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The side lock recesses are additionally machined into the standard shank product before assembly into the tool holder. This preliminary machining ensures that the recesses have the required precise dimensions and tolerances to engage with the side lock bolts and key, preventing axial and rotational movement.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If multiple locking mechanisms (side lock bolts and key) are used, then the cutting tool is securely fixed, but the device structure becomes more complex

Engineering Contradiction:
Improvesecurity of tool fixationVSAvoidnumber of locking components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The side lock bolts and key work together as an integrated locking system. The side lock bolts prevent axial movement by engaging with the additionally machined side lock recesses, while the key prevents rotational movement by engaging with the keyway. These mechanisms are merged into a single tool holder assembly that provides comprehensive tool securing.

Inventive Principle:
Principle #5Merging (Combining)

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 design allows for reliable and stable holding of cutting tools, preventing axial movement during high-speed machining by utilizing a collet with precise tolerances and multiple locking mechanisms, enhancing tool life and machining precision.

Implementation Method 1

a tapered collet (20)... an outer diameter of an outer peripheral surface of the distal end region gradually increases toward a distal end of the collet

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a key (50)... contacts the side lock recess (62) in a rear end portion of the additionally machined cutting tool (60)

Methodology Applied
Scientific EffectMechanical interlocking: Mechanical Fastener

Implementation Method 3

The first side lock bolt (30) passes through the first through hole (16), and a distal end of the first side lock bolt (30) contacts the first flat portion (24) of the collet (20)

Methodology Applied
Scientific EffectMechanical contact and constraint: Mechanical Fastener

Data Source

PatentEP4442391B1Tool holder and tool holding structure including the same
Publication Date: 2025.12.17 NIKKEN KOSAKUSHO WORKS LTD
  • EP4442391B1 patent drawingFigure 1
  • EP4442391B1 patent drawingFigure 2~3
  • EP4442391B1 patent drawingFigure 4(A)~4(C)

AI summary

A tool holder (1) includes a holder body (10), a tapered collet (20), a first side lock bolt (30), a second side lock bolt (40), and a key (50). The key (50) fits in a keyway (22) of the collet (20), contacts the inner peripheral surface of a front hole (13), and contacts a recess (62) formed in a rear end portion of a cutting tool (60) inserted into a tool insertion hole (21b) of the collet (20).