Internal Gear Skiving Chip Removal via Centrifugal Force Reversal

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Solution Overview

Problem

High-speed machining of internally toothed workpieces with tapering free spaces poses challenges in chip removal due to centrifugal forces, leading to accumulation and potential damage to the workpiece or tool, as conventional methods like fan-assisted chip removal are ineffective at high speeds.

Innovation Solution

A method involving a rotating externally toothed tool at a crossed axis angle, where mechanical force is applied to chips opposite to their centrifugal force origin, reducing their azimuthal velocity component and guiding them with a high-mass impact partner to prevent accumulation and facilitate removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-speed machining is performed with workpiece rotation speed greater than 600 rpm, then productivity is improved, but chips accumulate within the workpiece due to centrifugal forces causing damage or destruction

Engineering Contradiction:

Improveworkpiece rotation speedVSAvoidchip accumulation and damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful centrifugal force into a beneficial effect by using it to throw chips against the workpiece wall, where they are then removed by gravity and friction. The high rotation speed that previously caused chip accumulation is now utilized to actively eject chips from the machining zone through controlled impact with the workpiece wall.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The workpiece wall acts as an intermediary element between the chips and the chip removal system. Chips are thrown against the workpiece wall, which serves as an intermediate surface where chips accumulate temporarily before being removed by gravity and friction, preventing direct damage to the machining zone.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If conventional fan-assisted chip removal is used, then chip removal is effective at low speeds, but it can no longer effectively capture all chips at high speeds greater than 600 rpm

Engineering Contradiction:

Improvechip removal effectivenessVSAvoidworkpiece rotation speed

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent replaces the conventional fan-assisted chip removal system with a gravity-based passive removal system. Instead of using mechanical fans to blow chips away, the system relies on gravity and friction forces acting on chips after they are thrown against the workpiece wall, enabling effective chip removal at high rotation speeds where fans become ineffective.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the radial extent of free space is narrowed for socket-like connection, then workpiece functionality is improved, but chip accumulation occurs more easily in front of the taper point

Engineering Contradiction:

Improveworkpiece functionality for socket connectionVSAvoidchip accumulation in free space

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The narrowed free space that previously facilitated chip accumulation is now utilized beneficially. The restricted space causes chips to be thrown against the workpiece wall more effectively, and the taper point geometry creates conditions where gravity and friction can more efficiently remove chips, converting the potential harm of limited space into a beneficial chip ejection mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 prevents chip accumulation and damage by reducing centrifugal forces to near zero, ensuring safe and efficient machining of internally toothed workpieces at high speeds, extending the applicability of skiving to complex geometries like those with tapering free spaces.

Implementation Method 1

the movement of occurring chips that are subjected to centrifugal force in the area in front of the Taper location changes

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the movement of occurring chips that are subjected to centrifugal force in the area in front of the Taper location changes by mechanical force in a manner opposite to the origin of centrifugal force

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP2961553B1Method for cutting or machining internal gear teeth and machine tool

Publication Date: 2019.03.13 GLEASON PFAUTER MASCHFAB

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AI summary

The invention relates to a method for cutting or machining internal gear teeth of a workpiece that can be rotated about its rotational axis and radially delimits a free space which extends axially on one side beyond the internally toothed section and the radial extension of which tapers in at least one portion in the direction of extension. An externally toothed tool which is driven to rotate about its rotational axis is brought into rolling engagement with the internally toothed section from the other side and at a crossed-axes angle, the motion of chips that are produced and that are subject to a centrifugal force being changed by mechanical force in the region of the tapered portion contrary to the origin of the centrifugal force.