Grinding Worm Dressing With Variable Tip Radius for Gear Geometry

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Solution Overview

Problem

Existing diagonal generating grinding methods face challenges in maintaining precise gear geometry due to wear of grinding worms, leading to undesirable deviations in gearing geometry, which requires frequent dressing to restore the desired geometry.

Innovation Solution

A method for dressing grinding worms where the tip circle radius varies over the worm width, allowing for separate processing of tooth tips and flanks, with the profile of the addendum circle radius specified independently of the tooth flanks' geometry, enabling adjustments in cross-axis angle and center distance to maintain desired gear geometry without affecting the root circle radius.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the grinding worm is dressed to maintain desired tooth geometry, then manufacturing precision is improved, but the device complexity increases due to separate machining steps for tooth tips and flanks

Engineering Contradiction:
Improvegear geometry precisionVSAvoiddressing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The dressing process is segmented into two independent operations: dressing the tooth flanks and dressing the tooth tips. This allows each operation to be optimized separately for its specific geometric requirements, with the flank dresser and tip dresser being independently controllable and positioned

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tip circle radius is made variable across the worm width through dynamic positioning of the tip dresser. The distance of the tip dresser from the worm axis can be changed depending on the worm width position, enabling the creation of a variable tip circle radius profile that compensates for wear and maintains precise gear geometry

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the tip circle radius varies across worm width, then adaptability is improved for different gear grinding requirements, but manufacturing precision of root circle radius may deteriorate

Engineering Contradiction:
Improveprocessing flexibilityVSAvoidroot circle radius precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The dressing operations are completely separated: the flank dresser maintains the root circle radius and tooth flank geometry, while the tip dresser independently creates the variable tip circle radius profile. This segmentation ensures that variations in tip radius do not affect root circle precision

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the grinding worm are given different properties: the root area is maintained with constant precision by the flank dresser, while the tip area is given a variable radius profile by the tip dresser. Each region is treated with the appropriate dressing operation to achieve its specific quality requirements

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If separate machining steps are used for tooth tips and flanks, then manufacturing precision is improved, but productivity decreases due to additional machining time

Engineering Contradiction:
Improvetooth geometry precisionVSAvoiddressing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The tip circle radius profile is predetermined and calculated based on the desired gear geometry requirements before the dressing operation begins. This allows the tip dresser to be positioned and programmed in advance, eliminating the need for complex real-time calculations during the actual dressing process

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Both the flank dresser and tip dresser operate simultaneously on the rotating worm during the dressing process. The continuous rotation of the worm allows both dressers to work in parallel, maintaining continuous useful action and maximizing productivity while achieving precise geometry

Inventive Principle:
Principle #20Continuity of useful action

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 approach provides a further degree of freedom in processing, allowing for changes in cross-axis angle and center distance without undesirable effects on the root circle radius, enabling precise control of the gear geometry and efficient dressing of grinding worms.

Implementation Method 1

Dressing is performed by engaging a dressing tool with the grinding worm and removing material until the desired tooth geometry is restored

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP3281733B1Method of aligning a grinding worm
Publication Date: 2023.08.30 LIEBHER VERZAHNTECHNIK GMBH
  • EP3281733B1 patent drawingFigure 1
  • EP3281733B1 patent drawingFigure 2
  • EP3281733B1 patent drawingFigure 3

AI summary

The present invention relates to a method for dressing a grinding worm, which can be used for gear machining a workpiece by a generating grinding method, the grinding worm being dressed in such a way that the tip circle radius of the grinding worm varies over the worm width.