Face Gear Cutting Tool Geometry for Helical Gear Meshing

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Solution Overview

Problem

Current methods for cutting face gears to be meshed with helical gears lack precision and efficiency, particularly in mass production, and existing tools are difficult to handle and maintain.

Innovation Solution

A tool with a spur gear shape featuring a cutting edge portion that mimics the tooth-profile curvilinear shape of the helical gear, having a smaller circular tooth thickness and larger tooth depth, and a face width that satisfies specific geometric relationships, allowing for precise and efficient cutting of skew gears, including face gears, with optional auxiliary plates for reinforcement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If gear cutting is performed by machining cutting with a machining center using a ball end mill and theoretical tooth profile coordinates, then manufacturing precision of the tooth profile is improved, but productivity deteriorates because it takes a long time for machining

Engineering Contradiction:
Improvetooth profile precisionVSAvoidmachining speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The cutting process is divided into two distinct stages: rough cutting using a shaper cutter with undulating cutting edge to remove bulk material efficiently, and finish cutting using a ball end mill to achieve precise tooth profile. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between productivity and precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shaper cutter performs preliminary rough cutting to create the basic tooth shape and remove excess material before the finish cutting stage. By preparing the workpiece in advance with the rough cutter, the subsequent precision machining requires less time and removes less material, thereby improving overall productivity while maintaining high precision.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If gear cutting is performed by shaper cutter to improve productivity, then manufacturing efficiency is improved, but manufacturing precision deteriorates and tooth flank modification becomes difficult

Engineering Contradiction:
Improvemachining efficiencyVSAvoidtooth profile precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The cutting process is divided into two distinct stages: rough cutting using a shaper cutter with undulating cutting edge to remove bulk material efficiently, and finish cutting using a ball end mill to achieve precise tooth profile. This segmentation allows each stage to optimize for its specific function, resolving the contradiction between productivity and precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameters of the shaper cutter by equipping it with an undulating cutting edge profile that creates alternating heavy and light sections of material. This parameter change allows the shaper cutter to perform both rough cutting and certain程度的 finish cutting, improving productivity while maintaining acceptable precision without requiring complete reliance on slow CNC machining.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If forging or casting is used for mass production, then productivity is improved, but manufacturing precision deteriorates because achievable precision differs depending on die electrode precision

Engineering Contradiction:
Improvemass production capabilityVSAvoidmeshing precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The shaper cutter performs preliminary rough cutting to create the basic tooth shape and remove excess material before the finish cutting stage. By preparing the workpiece in advance with the rough cutter, the subsequent precision machining requires less time and removes less material, thereby improving overall productivity while maintaining high precision.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention extracts the precision-critical finishing operation from the mass production forging/casting process. By using a dedicated two-stage cutting process with specialized cutters, the precision requirements are separated from the high-volume production process, allowing forging/casting to focus on efficient material formation while the cutting process ensures consistent high precision across all produced gears.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP2664403B1Tool for cutting gear and method for cutting gear
Publication Date: 2021.07.28 OGASAWARA PRECISION LABORATORY CO LTD
  • EP2664403B1 patent drawingFigure 1(a)~1(d)
  • EP2664403B1 patent drawingFigure 2(a)~2(d)
  • EP2664403B1 patent drawingFigure 3(a)~3(d)

AI summary

There is provided a tool for efficiently cutting a face gear to be meshed with a helical gear. When a circular tooth thickness of a tooth tip of a cutting edge portion is represented as SatSC, a circular tooth thickness on a virtual outside diameter of a tooth profile of the helical gear in a cross-sectional view perpendicular to an axis is represented as Sat, a helix angle on the virtual outside diameter of the tooth profile of the helical gear in a cross-sectional view by a plane perpendicular to the axis is represented as βa, and a face width of the cutting edge portion is represented as bsc, bS⁢C≦Sat-SatSCtanβa is satisfied.