Gear Milling Insert Asymmetry for Involute Accuracy
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Solution Overview
Problem
Existing gear milling tools face challenges in achieving high accuracy and economic efficiency due to negative cutting geometry, which results in errors in the involute shape of milled cogs and limited tool life.
Innovation Solution
A replaceable cutting insert with positive cutting geometry, featuring an acute clearance angle between the extension plane and edge side, allowing optimal positioning and ensuring high accuracy and extended tool life through asymmetrical design and reinforcement bevels, along with indexable cutting edges for enhanced utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cutting insert with negative cutting geometry is used to achieve structural simplicity, then the chip surface can be positioned parallel to the extension plane, but the involute accuracy of the milled cogs deteriorates due to errors in the cutting path
Solution Approach 1:
The cutting insert employs asymmetrical geometry where the chip surface is tilted at a specific angle (5° to 15°) relative to the extension plane, creating different angles between the chip surface and the primary/secondary main cutting edges. This asymmetry compensates for the errors inherent in negative cutting geometry, enabling high involute accuracy while maintaining a relatively simple insert structure.
2Duration of action of moving object
If replaceable cutting inserts are used to improve tool life and economic efficiency, then the milling tool can operate for extended periods, but the positioning accuracy and repeatability of the inserts deteriorate
Solution Approach 1:
The cutting insert is designed as a separate, replaceable component with a modular structure that includes a body portion and a cutting edge portion. This segmentation allows the cutting insert to be easily replaced when worn, while the standardized geometry and mounting interface ensure consistent positioning accuracy across multiple inserts and replacements.
Solution Approach 2:
The cutting insert incorporates specific geometric parameters, including the tilted chip surface angle (5° to 15°) and the acute clearance angle (5° to 15°) between the normal to the extension plane and the edge side. These standardized parameter specifications ensure that each replaceable insert maintains the required positioning accuracy and cutting performance, regardless of how many times it is replaced.
3Manufacturing precision
If the chip surface is tilted to achieve positive cutting geometry, then the cutting accuracy and tool life are improved, but the structural complexity of the cutting insert increases
Solution Approach 1:
The cutting insert employs asymmetrical geometry where the chip surface is tilted at a specific angle (5° to 15°) relative to the extension plane, creating different angles between the chip surface and the primary/secondary main cutting edges. This asymmetry compensates for the errors inherent in negative cutting geometry, enabling high involute accuracy while maintaining a relatively simple insert structure.
Solution Approach 2:
The tilting of the chip surface and the acute clearance angle are applied locally to specific regions of the cutting insert, particularly at the cutting edges where they are most needed for accurate cutting. The rest of the insert structure remains relatively simple and straightforward, minimizing overall structural complexity while achieving the required cutting accuracy where it matters most.
Data Source
Figure 1
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AI summary
A cutting insert for a gear milling tool comprises an under side (21), an opposite upper side (22) that forms a chip surface and is parallel to an extension plane (p), a circumferential edge side (23) that connects the upper side and the under side. A centre axis (A) extends through the under side. A symmetry line (S) is perpendicular to the centre axis. A first cutting edge (24) comprises a primary main cutting edge (24'), a secondary main cutting edge (24") - which are symmetrical in respect of the symmetry line - and a transverse end cutting edge (24a) between the primary and the secondary main cutting edge. A normal to the extension plane (p) forms an acute clearance angle with the edge side (23) at least along the first cutting edge (24) so that the cutting insert (2) obtains a positive cutting geometry.