Thread Former With Offset Interruptions for Wear Reduction

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Solution Overview

Problem

Existing thread formers experience significant wear during the thread forming process due to heat generation and friction, leading to reduced processing speed and increased wear, which limits the number of threads that can be produced before wear occurs.

Innovation Solution

The thread former design features axially adjacent web sections with interruptions offset at different angular positions, guiding coolant and lubricant through a zigzag path over the polygonal cross-section corners, ensuring effective cooling and lubrication of the most stressed areas, thereby reducing wear and increasing the number of threads that can be produced without significant wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coolant and lubricant grooves are provided in the forming section, then wear is reduced, but the structural complexity increases

Engineering Contradiction:
Improvewear resistanceVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The forming section is divided into multiple axially adjacent web sections, each with interruptions at different angular positions. This segmentation allows coolant and lubricant to reach different areas through the interruptions, providing comprehensive cooling and lubrication without requiring complex groove systems throughout the entire forming section.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of providing coolant grooves in the conventional axial direction, the invention uses interruptions in the web sections that are offset at different angular positions. This transforms the coolant delivery from a single-dimensional axial flow to a multi-dimensional zigzag path through the interruptions, achieving better coverage without increasing structural complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the thread former is used for producing threads in blind holes, then adaptability is improved, but cooling and lubrication efficiency deteriorates due to limited coolant access

Engineering Contradiction:
Improveapplicability to blind holesVSAvoidcooling efficiency
Core Design Contradiction:
Adaptability or versatilityVSTemperature

Solution Approach 1:

Coolant and lubricant are supplied in advance through the interruptions in the web sections before the thread forming process begins. This preliminary action ensures that the forming section is pre-cooled and lubricated, allowing effective operation in blind holes where coolant access is limited during the actual forming process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The interruptions in the web sections act as intermediaries that facilitate the delivery of coolant and lubricant to the forming section. These interruptions create pathways that allow the coolant to reach the critical areas even in blind hole applications where direct coolant access is restricted.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If interruptions are arranged at the same angular position on all web sections, then manufacturing simplicity is maintained, but cooling and lubrication coverage is insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcooling and lubrication coverage
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The interruptions in axially adjacent web sections are arranged asymmetrically at different angular positions rather than at the same angular position. This asymmetric arrangement ensures that coolant and lubricant flow through different pathways, providing comprehensive coverage of all corner areas of the polygonal cross section and improving cooling and lubrication effectiveness.

Inventive Principle:
Principle #4Asymmetry

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 significantly reduces wear on the forming section and allows for a substantial increase in the number of threads that can be produced before wear occurs, compared to conventional thread formers, by forcibly guiding coolant and lubricant over the deformation work areas, enhancing both cooling and lubrication efficiency.

Implementation Method 1

coolant and lubricant supplied via the shaft and the interruptions along a zigzag path through the interruptions and along groove sections between the shaping webs must flow through the next axial interruption

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

guiding coolant and lubricant through a zigzag path over the polygonal cross-section corners, ensuring effective cooling and lubrication of the most stressed areas

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

produce internal threads in bores by plastically deforming the material of the inner wall of the bore

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 4

During the plastic deformation of the material in which a corresponding thread is formed, depending, among other things, on the speed at which the thread forming takes place, a considerable amount of heat is generated (also due to friction)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3124154B1Thread former
Publication Date: 2019.10.09 WALTER AG
  • EP3124154B1 patent drawingFigure 1a~1d
  • EP3124154B1 patent drawingFigure 2a~2d
  • EP3124154B1 patent drawingFigure 3a~3d

AI summary

The present invention relates to a thread former (10) with a shank (1) and a forming section (2) having a polygonal cross-section, wherein a web (3) or several webs (3) of the thread former extend along the circumference of the forming section (2) such that the forming section (2) has at least two axially adjacent webs (3) or web sections, each of which has at least one interruption (4). In order to create a thread former in which wear is further reduced and the machining speed or the number of threaded holes produced can be further increased without increasing wear, or even with a reduction in wear, it is proposed according to the invention that at least some of the interruptions (4) are arranged at different angular positions on axially adjacent web sections.