Lightweight Rotary Tool Structure for Thermal-Stable Bore Machining

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Solution Overview

Problem

Conventional rotary tools face challenges in maintaining precision and dimensional accuracy when machining large inner diameters due to thermal expansion and weight-related issues, especially when high material removal rates lead to increased heat input and centrifugal forces.

Innovation Solution

A rotary tool design featuring a lightweight support structure with a corset structure that limits thermal expansion, using materials with low coefficients of thermal expansion such as Invar, titanium, or carbon fiber composites, to minimize geometric changes and ensure precise machining of large inner diameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If material removal volume is increased to improve productivity, then productivity increases, but thermal expansion of the support structure worsens due to higher heat input

Engineering Contradiction:
Improvematerial removal rateVSAvoiddimensional accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter of the support structure by using a material with low thermal expansion coefficient (such as invar, titanium, or carbon fiber composites) instead of conventional materials. This parameter change allows the support structure to maintain dimensional stability even when subjected to high heat input from increased material removal rates, thus resolving the contradiction between productivity and manufacturing precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials, specifically carbon fiber composites, for the support structure. These composite materials provide both the required mechanical strength for high material removal operations and low thermal expansion properties to maintain dimensional accuracy, thereby enabling both high productivity and high precision simultaneously

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If the support structure is made heavier to improve stiffness and reduce vibration, then manufacturing precision improves, but the weight of the rotary tool worsens affecting handling and centrifugal forces

Engineering Contradiction:
Improvedimensional accuracyVSAvoidtool weight
Core Design Contradiction:
Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent uses carbon fiber composites for the support structure, which provide high stiffness-to-weight ratio. These composite materials deliver the necessary structural rigidity to minimize vibration and maintain dimensional accuracy during machining, while simultaneously keeping the tool weight low for improved handling and reduced centrifugal forces

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by selecting materials with high specific stiffness (stiffness per unit weight). This parameter change allows the support structure to achieve the required stiffness for precision machining without increasing weight, thus resolving the contradiction between manufacturing precision and tool weight

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional materials are used for the support structure, then ease of manufacture improves, but thermal expansion worsens leading to loss of dimensional accuracy

Engineering Contradiction:
ImprovemanufacturabilityVSAvoiddimensional accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from conventional materials with high thermal expansion coefficients to advanced materials with low thermal expansion coefficients. This parameter change prioritizes dimensional accuracy over ease of manufacture, accepting that manufacturing these specialized materials may be more complex but achieving superior precision outcomes

Inventive Principle:
Principle #35Parameter changes

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 achieves high precision and dimensional accuracy even with high cutting performance, limiting thermal expansion of the cutting edge area to within a few micrometers, enabling effective machining of large inner diameters with reduced weight and improved handling.

Implementation Method 1

the support structure heats up and expands according to its coefficient of thermal expansion

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the brace structure located radially inside through frictional and/or positive locking

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

The support structure is of lightweight construction, and the region of the support structure directly or indirectly supporting the cutting edge is limited with regard to thermal expansion

Methodology Applied
Scientific EffectLightweight construction:

Data Source

PatentEP3566802B1Rotary tool
Publication Date: 2024.05.15 GUEHRING KG
  • EP3566802B1 patent drawingFigure 1
  • EP3566802B1 patent drawingFigure 2~3
  • EP3566802B1 patent drawingFigure 4~5

AI summary

The invention relates to a rotary tool (1; 101; 201; 301; 401) for machining large internal diameters, on the outer circumference (2) of which at least one cutting edge (4; 104; 204) is arranged, with a support structure (10; 110; 210; 310; 410) which has a supporting area (14; 114; 214) which indirectly or directly supports the cutting edge (4; 104; 204), and a clamping section (24; 124, 224; 324; 424) for coupling to a tool holder, wherein the support structure (10; 110; 210; 310; 410) is designed in a lightweight construction and the area (14; 114; 214) which indirectly or directly supports the cutting edge (4; 104; 204) 214) of the support structure (10; 110; 210; 310; 410) with respect to thermal expansion by a corset structure (12; 112; 212; 312; 412).