Self-Centering Clamping Connection for Milling Tool Heads

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Solution Overview

Problem

Milling tools with small diameters face challenges in accommodating a large number of cutting edges while maintaining a simple and precise attachment of the cutting head to the tool shank, often requiring tight tolerances and mechanical fine machining.

Innovation Solution

A milling tool design featuring a self-centering clamping connection between the cutting head and tool shank, where the projection and recess are configured to form a non-positive interaction with clamping surfaces, allowing for reliable attachment without mechanical post-processing of the cutting head, enabling cost-effective production and low fastening forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a form-fitting connection with tight tolerances is used to attach the cutting head to the tool shank, then the attachment reliability is improved, but the manufacturing complexity and cost increase due to requiring mechanical fine machining

Engineering Contradiction:
Improveattachment reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cutting head is designed with a self-centering projection that automatically centers itself on the tool shank during insertion, eliminating the need for complex mechanical fine machining. The projection's geometry provides self-alignment through geometric constraints rather than requiring precision-machined mating surfaces

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the attachment mechanism from relying on tight dimensional tolerances to relying on geometric self-centering parameters. The projection is designed with specific angular parameters (e.g., 60-degree included angle) that provide self-centering action, transforming the attachment reliability from tolerance-dependent to geometry-dependent

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a self-centering clamping connection is used to attach the cutting head, then the manufacturing cost decreases by eliminating mechanical fine machining, but the attachment precision must be maintained

Engineering Contradiction:
Improvemanufacturing costVSAvoidattachment precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The self-centering projection automatically achieves precise alignment during assembly without requiring precision machining of the cutting head. The geometric design of the projection and its interaction with the tool shank's recess provide self-alignment, maintaining attachment precision while enabling cost-effective powder metallurgy manufacturing

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The projection is pre-designed with specific geometric parameters that ensure self-centering action occurs automatically during the attachment process. The angular parameters and dimensions are predetermined to provide the necessary self-alignment, eliminating the need for post-manufacturing precision work

Inventive Principle:
Principle #10Preliminary action

3Productivity

If a large number of cutting edges are arranged on a small-diameter milling tool, then the productivity increases, but the space available for the cutting head attachment decreases

Engineering Contradiction:
Improvenumber of cutting edgesVSAvoidattachment area
Core Design Contradiction:
ProductivityVSArea of stationary object

Solution Approach 1:

The cutting head is segmented into multiple cutting edges arranged around the periphery, allowing maximum utilization of the small diameter. The self-centering projection design occupies minimal space at the center, leaving maximum area available for arranging multiple cutting edges on the cutting head's periphery

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The projection is nested within the cutting head structure, with its self-centering function integrated into the cutting head's overall geometry. This nested design minimizes the space required for the attachment mechanism, allowing more area to be dedicated to cutting edges

Inventive Principle:
Principle #7Nested doll (Nesting)

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 a reliable, self-locking attachment of the cutting head to the tool shank with low operational forces, facilitating the use of a large number of cutting edges on small-diameter milling tools without the need for mechanical fine machining, ensuring efficient and cost-effective manufacturing.

Implementation Method 1

the clamping surfaces and the second areas of the centering surfaces, which effect the force-fit, run at least substantially tangentially to a circle whose center lies on the longitudinal axis of the milling tool

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2958693B1Milling tool
Publication Date: 2019.05.08 CERATIZIT AUSTRIA GES
  • EP2958693B1 patent drawingFigure 1~3
  • EP2958693B1 patent drawingFigure 4~6
  • EP2958693B1 patent drawingFigure 7~8

AI summary

A milling tool (1) is provided, comprising: a tool shank (2) with a longitudinal axis (L), and a cutting head (4), which is secured at an end face to the tool shank (2) and has a plurality of cutting edges (4a) for the machining of a workpiece. The tool shank (2) and the cutting head (4) are connected to one another by way of a clamping connection. The clamping connection has a projection (11) with a plurality of clamping areas (12) around the circumference and a clearance (3) with a plurality of centring areas (6) around the circumference, interacting with the clamping areas (12). The centring areas (6) have in each case a first region (6a), where the centring areas (6) are at a first distance from the longitudinal axis (L) in a section perpendicular to the longitudinal axis (L), and the first region (6a) goes over into a second region (6b), where the centring areas (6) are at a smaller, second distance from the longitudinal axis (L) in the section perpendicular to the longitudinal axis (L), and so the clamping areas (12) of the projection (11) can be inserted into the clearance (3) between the first regions (6a) of the centring areas (6) and, by rotation of the cutting head (4) in relation to the tool shank (2) about the longitudinal axis (L), can be moved into a clamping position, in which the clamping areas (12) interact in a frictionally engaging manner with the second regions (6b) of the centring areas (6).