Gear Skiving Tooth Machining for Chip Removal and Even Tool Wear

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Solution Overview

Problem

Existing gear machining methods face issues with uneven tool wear and inefficient chip removal, leading to reduced machining efficiency and increased risk of chip entrapment.

Innovation Solution

The method involves changing the center distance and angle of rotation between the tool and workpiece during machining steps to alternate cutting contours closer to both flanks of the workpiece, ensuring even loading and increased chip removal by machining over the entire tooth height, particularly using a consistent angle of twist for machining steps closer to the second flank.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a fixed angle of rotation is superimposed on the rolling coupling for each processing step to connect flank cuts and prevent U-shaped chips, then chip entrapment is prevented, but tool wear becomes very uneven

Engineering Contradiction:
Improvechip entrapmentVSAvoidtool wear uniformity
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies periodic action by alternating the superimposed rotation angle between positive and negative values across consecutive machining steps. This periodic variation ensures that both left and right tooth flanks are machined alternately, distributing the mechanical load evenly between both flanks of the tool, thereby preventing uneven tool wear while maintaining effective chip removal

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes the rotation angle parameter dynamically during the machining process. Instead of using a fixed angle, the method varies the angle between steps (e.g., +5° then -5°, or +10° then -10°), which allows the cutting action to alternate between left and right flanks, achieving uniform tool wear while preventing chip entrapment

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the angle of rotation changes sign after each machining step to machine left and right flanks alternately, then tool wear becomes symmetrical, but chip removal efficiency decreases

Engineering Contradiction:
Improvetool wear uniformityVSAvoidchip removal efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent uses periodic action with an extended period, applying the same sign of rotation angle for multiple consecutive machining steps (e.g., three or more steps with positive angle, then switching to negative angle for three or more steps). This extended periodic pattern allows continuous machining of one flank over the entire tooth height, maximizing chip removal efficiency while still achieving symmetrical tool wear over the complete cycle

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent ensures continuity of useful action by machining each flank over the entire tooth height already produced during the consecutive steps with the same angle sign. This continuous cutting action across the full tooth height maximizes material removal rate and chip removal efficiency, while the alternation between flanks maintains symmetrical tool wear

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If the tool machines the workpiece over the entire tooth height already produced, then chip removal per machining step is increased, but the complexity of controlling the machining process increases

Engineering Contradiction:
Improvechip removal per stepVSAvoidmachining process control
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the superimposed rotation angle adjustable and variable during the machining process. The angle can be dynamically changed between steps and adapted to different machining conditions, allowing optimization of chip removal while maintaining manageable process control through systematic angle variation patterns

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3620251B1Method for machining a workpiece to produce teeth and machine and software for carrying out the method
Publication Date: 2023.03.01 LIEBHER VERZAHNTECHNIK GMBH
  • EP3620251B1 patent drawingFigure 1
  • EP3620251B1 patent drawingFigure 2
  • EP3620251B1 patent drawingFigure 3

AI summary

The present invention discloses a method for machining the gear teeth of a workpiece (1) using a tool in which the rotation of the tool is coupled to the rotation (20) of the workpiece, in particular gear machining of a workpiece by gear skiving, wherein the gear machining is carried out in several machining steps (S1-S11), wherein between two machining steps the center distance and/or a rotation angle superimposed on the rolling coupling between the workpiece and the tool are changed, so that in each machining step the tool cuts a contour which alternately approaches a first (2) and a second (3) flank of the desired gear teeth of the workpiece. It is provided that the same rotation angle is used for several machining steps (S1, S3, S5, S7...) which approach a second flank.