Machining Tool Fastening System for Insert Positioning

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Solution Overview

Problem

Conventional machining tools face challenges in ensuring reliable and exact positioning of cutting inserts and effective chip removal, especially when multiple cutting inserts are arranged spirally around the axis of rotation, due to complex alignment requirements and sensitivity to manufacturing tolerances.

Innovation Solution

The tool design features a fastening system with an unthreaded shank section and unthreaded bore section that allows for elastic deflection, providing lateral play and enabling cost-effective production, reduced sensitivity to manufacturing tolerances, and reliable positioning of cutting inserts in multiple directions without additional contact surfaces, thus facilitating efficient chip removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If both lateral contact surfaces are provided for radial and axial positioning of the cutting insert, then positioning reliability is improved, but chip evacuation capability deteriorates

Engineering Contradiction:
Improvepositioning reliabilityVSAvoidchip evacuation capability
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention removes the axial lateral contact surface from the seat design, extracting only the necessary contact elements (base surface and radial lateral contact surface) while eliminating the harmful axial constraint that interferes with chip evacuation. The axial positioning function is transferred to the fastening screw mechanism instead.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The fastening screw acts as an intermediary element that provides axial positioning and clamping force without requiring a lateral contact surface on the seat. The screw's conically enlarged intermediate section and head deflection mechanism mediate between the cutting insert and the seat, achieving axial positioning through a different mechanical path that does not obstruct chip flow.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If precise dimensioning and matching of fastening screw and bore are used for axial alignment, then positioning precision is improved, but manufacturing cost increases

Engineering Contradiction:
Improveaxial alignment precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention changes the parameter relationship between the fastening screw and bore from precise dimensional matching to intentional dimensional mismatch. The bore is designed with larger dimensions than the unthreaded shank section, creating clearance that allows elastic deflection. This parameter change transforms the system from tolerance-sensitive to tolerance-insensitive, reducing manufacturing costs while maintaining positioning precision through the elastic deflection mechanism.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The conically enlarged intermediate section of the fastening screw provides beforehand cushioning by distributing clamping forces gradually during tightening. This conical geometry allows progressive engagement and elastic deflection, cushioning against dimensional variations and manufacturing tolerances before final positioning is achieved, thereby reducing sensitivity to precise dimensioning.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If multiple cutting inserts are arranged spirally around the tool body, then cutting performance is improved, but positioning difficulty increases

Engineering Contradiction:
Improvecutting performanceVSAvoidpositioning difficulty
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The invention creates a universal fastening mechanism that handles multiple positioning functions (radial positioning, axial positioning, and clamping) through a single integrated fastening screw design. This multi-functional approach simplifies the overall positioning system for multiple cutting inserts arranged spirally, as each insert uses the same fastening principle regardless of its position around the tool body.

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

Solution Approach 2:

The fastening screw incorporates dynamic elements including elastic deflection of the screw head and guided movement of the conically enlarged intermediate section through an elongated slot. This dynamic mechanism allows the fastening system to adapt to slight variations in insert positioning and maintains reliable clamping across multiple spirally arranged inserts without requiring complex static positioning features.

Inventive Principle:
Principle #15Dynamics

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

This design allows for cost-effective, robust, and precise positioning of cutting inserts, improving chip evacuation and reducing manufacturing costs while maintaining reliable alignment and positioning, even with multiple inserts arranged spirally around the axis of rotation.

Implementation Method 1

tightening the fastening screw to secure the cutting insert to the seat allows free movement of the unthreaded shank section in both the axial and radial directions. Since the fastening screw is deflected elastically when the cutting insert is attached to the seat, causing the unthreaded shank section to contact the unthreaded bore section on a side facing away from the lateral contact surface

Methodology Applied
Scientific EffectElastic deflection: Elasticity

Data Source

PatentEP3223983B1Machining tool
Publication Date: 2020.03.04 CERATIZIT AUSTRIA GES
  • EP3223983B1 patent drawingFigure 1~2
  • EP3223983B1 patent drawingFigure 3~5
  • EP3223983B1 patent drawingFigure 6~7

AI summary

The invention relates to a machining tool (1) comprising the following: a main part (2), at least one seat (3) formed on the main part (2), a securing screw (5), and a cutting insert (4) which is secured to the seat (3). The seat (3) has a base surface (3a) for supporting a lower face of the cutting insert (4) and a lateral contact surface (3b). The base surface (3a) is equipped with a bore (6) for receiving the securing screw (5), said bore having a threaded bore section (6a) and a thread-free bore section (6b) closer to the base surface (3a). The cutting insert (4) is secured to the seat (3) such that the head portion (5b) of the securing screw (5) rests against the through-hole (7) of the cutting insert (4), a threaded section (5a) of the securing screw (5) interacts with the threaded bore section (6a), and the securing screw (5) is elastically deflected such that a thread-free shaft section (5c) rest against the thread-free bore section (6b) on a face facing away from the lateral contact surface (3b) and is spaced from the thread-free bore section (6b) on the face facing the lateral contact surface (3b).