Thread Milling Clearance Geometry for Vibration-Stable Cutting
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Solution Overview
Problem
Prior thread milling cutting tools are prone to vibrations, leading to insufficient surface finish and potential damage, due to either excessive digging into the workpiece material with large clearance angles or high friction with small clearance angles.
Innovation Solution
The thread milling cutting tool features a unique clearance surface design with a smaller radial clearance angle directly behind the cutting edge and a larger angle further behind, providing improved stability and reduced pressure on the workpiece, thereby minimizing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large radial clearance angle is used on the clearance surface, then the tool is easier to cut and material removal is improved, but the tool digs deep into the workpiece material causing uneven cutting and vibrations
Solution Approach 1:
The clearance surface is designed with varying radial clearance angles at different locations: a larger angle at the rotationally leading portion for easy cutting, and a smaller angle at the rotationally trailing portion for stability. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The radial clearance angle parameter is changed along the rotationally trailing direction, transitioning from a larger angle near the cutting edge to a smaller angle further trailing. This parameter variation allows the tool to achieve both ease of cutting and cutting stability simultaneously.
2Stability of the object's composition
If a small radial clearance angle is used on the clearance surface, then cutting stability is improved and digging into the workpiece is avoided, but cutting forces and friction increase causing the tool to diverge from the intended path
Solution Approach 1:
Different regions of the clearance surface have different radial clearance angles optimized for their specific functions: the rotationally leading portion has a larger angle to reduce cutting forces, while the rotationally trailing portion has a smaller angle to maintain cutting stability and prevent tool divergence.
Solution Approach 2:
The clearance surface is segmented into at least two portions along the rotationally trailing direction, with each portion having a different radial clearance angle. This segmentation allows independent optimization of cutting force reduction and stability maintenance.
3Device complexity
If a constant radial clearance angle is used on the clearance surface, then the tool design is simplified, but the tool is prone to vibrations due to inability to balance cutting ease and stability
Solution Approach 1:
The clearance surface design incorporates local quality variation with different radial clearance angles in different portions, which reduces vibrations while maintaining reasonable design complexity through a systematic approach to angle variation.
Data Source
AI summary
A thread milling cutting tool for metal cutting includes an elongated main body having a cutting section, which extends axially rearward from a front end. The cutting section includes a plurality of teeth. The plurality of teeth include at least a first set of circumferentially spaced teeth, wherein each tooth of the at least first set has a same, first axial distance to the front end, and a clearance surface of each tooth has a radial clearance angle. The clearance surface of each tooth of the at least first set of teeth includes a rotationally leading portion and a rotationally trailing portion, wherein the leading portion extends from and rotationally behind the cutting edge, and the radial clearance angle (α) of the leading portion is smaller than the radial clearance angle (β) of the trailing portion.