Thread Milling Tool with Offset Combs for Crest Shape Control

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Solution Overview

Problem

Existing milling tools struggle to achieve high precision and controlled shape of thread crests during threading and tapping operations, particularly in precision applications, due to limitations in the accuracy and shape control of thread milling tools with alternating teeth.

Innovation Solution

A milling method and tool with multiple combs, including a first and second comb with teeth spaced at specific pitches and offset by a phase displacement, and a third comb for milling the truncated crest, allowing for precise control of thread flanks and crest shape, producing a triangular cross-section thread with a truncated crest.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a milling tool with alternating teeth is used to mill threads, then the flank accuracy is improved, but the crest shape control deteriorates

Engineering Contradiction:
Improveflank accuracyVSAvoidcrest shape control
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The milling tool is divided into multiple independent combs (first comb, second comb, third comb) with different functions. The first and second combs are responsible for milling the flanks with high precision, while the third comb is specifically dedicated to controlling the crest shape. This segmentation allows each comb to optimize its function independently, resolving the contradiction between flank accuracy and crest shape control.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the teeth of the milling tool are spaced at double the threading pitch, then the flank milling is simplified, but the machining speed deteriorates

Engineering Contradiction:
Improveflank milling simplicityVSAvoidmachining speed
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

Instead of using a single comb with double pitch spacing, the invention segments the tool into multiple combs with different tooth spacings. The first comb has teeth spaced at double the threading pitch for simplified flank milling, while the second comb has teeth spaced at the actual threading pitch to maintain machining speed. This segmentation allows both requirements to be satisfied simultaneously.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2801432B1Method for obtaining a complete threading profile by milling and milling tool
Publication Date: 2017.08.02 SAFELOCK
  • EP2801432B1 patent drawingFigure 1A~1B
  • EP2801432B1 patent drawingFigure 2~3
  • EP2801432B1 patent drawingFigure 4~5

AI summary

Method for milling a threading of a screw or tapped hole, said threading having a cross section in the shape of a triangle with a truncated crest, comprising: milling a first flank (V1) of at least one spire of said thread by means of a first comb (A) of a milling tool (F), wherein the teeth of said first comb (A) are spaced in relation to one another by a first pitch (P1); milling a second flank (V2) of at least one other spire of said thread by means of a second comb (B) of said milling tool (F), wherein the teeth of the second comb (B) are spaced in relation to one another by a second pitch (P2) equal to the first pitch (P1) and offset from the teeth of the first comb (A) by a phase displacement (DP); milling a truncated portion (V3) of said crest by means of a third comb (C) of said milling tool (F).