Tool Head Insert Positioning for Accurate Radial Blade Changes

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Solution Overview

Problem

Conventional cutterheads require significant effort to change blades, especially for wide blades, and suffer from accuracy issues due to centrifugal forces causing blade shift, necessitating prior disassembly of adjacent heads.

Innovation Solution

A tool head design with a centrifugal wedge and a pressure element that allows radial insertion and removal of cutting inserts, featuring a locking element and a spring or elastically deformable part for precise positioning, and a clamping screw for easy adjustment without hammers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a centrifugal wedge is used to clamp the cutting insert, then the clamping force is improved, but the blade can shift due to centrifugal forces at high speeds

Engineering Contradiction:
Improveclamping forceVSAvoidblade position accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

A pressure element is introduced as an intermediary component between the cutting insert and the tool holder groove wall. This pressure element applies a counteracting pressure force that opposes the centrifugal force acting on the cutting insert during rotation, thereby preventing blade shift and maintaining positioning accuracy while allowing the centrifugal wedge to provide strong clamping force

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The pressure element applies a preliminary counteracting force in the radial direction before the centrifugal force can cause significant blade displacement. By pre-positioning the blade against the groove wall with the pressure element, the system prevents harmful centrifugal displacement rather than correcting it after occurrence

Inventive Principle:
Principle #9Preliminary anti-action

2Ease of operation

If the groove narrows towards the outer surface to enable radial insertion, then ease of operation is improved, but the structural complexity increases

Engineering Contradiction:
Improvetool insertion/removalVSAvoidgroove structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The groove structure transitions from a static uniform cross-section to a dynamic varying cross-section that narrows towards the outer surface. This dynamic geometric progression allows the groove to provide radial insertion capability while maintaining structural integrity and enabling the centrifugal wedge mechanism to function effectively

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The tool holder structure is segmented into distinct functional zones: the narrowing groove section for radial tool insertion, the clamping section with centrifugal wedge, and the positioning section with pressure element. This segmentation allows each zone to optimize its specific function while contributing to the overall system performance

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple screws are used to secure wide blades, then reliability is improved, but the effort required for blade changing increases

Engineering Contradiction:
Improveblade securityVSAvoidblade changing effort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The traditional multi-screw fastening system is extracted and replaced with a centrifugal wedge mechanism. This single-component wedge system provides equivalent or superior clamping reliability for wide blades while eliminating the need for multiple screws, thereby significantly reducing the effort and time required for blade changing operations

Inventive Principle:
Principle #2Taking out (Extraction)

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 precise tool changes with minimized effort, maintaining accuracy by preventing blade displacement during operation, thus enhancing machining precision.

Implementation Method 1

A centrifugal wedge, which can be inserted into the groove, can press the locking element against the cutting insert and fix the latter in the tool holder

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

a pressure element is provided in the tool holder, which presses a cutting insert placed in the tool holder radially against a stop

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3623127B1Tool head and method for positioning a cutting plate in the tool holder of the tool head
Publication Date: 2026.02.18 OERTLI WERKZEUGE
  • EP3623127B1 patent drawingFigure 1
  • EP3623127B1 patent drawingFigure 2
  • EP3623127B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for inserting and automatically radially positioning a cutting insert, as well as a tool head (11a-d,f) for a woodworking machine with a cylindrical, conical, or profiled tool head body for the rotary machining of a workpiece. The tool holder comprises a groove (19) in which a cutting insert (15) can be clamped between a first groove wall (27) of the groove (19) and a locking element (25) serving as a pressure jaw. A first positive locking connection is provided between the cutting insert (15) and the stop (85, 85a) in the first groove wall (27). To facilitate gripping and precise insertion of the cutting insert (15) during tool changes, the base surface (108) of the cutting insert (15) is tilted at an angle greater than 90 degrees relative to the first groove wall (27). This enables radial insertion of a cutting insert (15).The tool head according to the invention also includes an elastic pressure element (73, 113a, 113b, 133) which automatically positions the cutting plate (15) radially outwards over the functional surface (94) during the clamping process and thus presses the cutting plate (15) positively against a radially inwards directed stop (85, 85a).