CNC Thread Cutting With Variable Oscillation for Chip Breaking
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Solution Overview
Problem
Existing threading methods in CNC-lathe machining face challenges with chip breaking and tool life due to V-shaped chip formation, which leads to poor chip control and increased risk of built-up edge on the rake face, resulting in reduced tool longevity.
Innovation Solution
A machining method involving a CNC-lathe that oscillates a threading tool at different frequencies during passes, with the second pass intersecting the first pass multiple times, ensuring the first and second cutting edges are alternatively in cut, distributing wear evenly and breaking chips as they exit the cut, thereby improving chip control and tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a threading tool oscillates at a constant frequency during all passes, then the machining process is simple to control, but the chips form a V-shape that is difficult to control and reduces tool life
Solution Approach 1:
The patent applies dynamics by changing the oscillation frequency from constant to variable across different passes. The first oscillating pass uses a first frequency, while the second oscillating pass uses a second frequency that is at least 1.5 times the first frequency. This dynamic adjustment optimizes chip breaking and control while maintaining manageable machining complexity.
Solution Approach 2:
The patent implements parameter changes by modifying the oscillation frequency parameter between passes. Specifically, the frequency is increased by at least 50% from the first pass to the second pass. This parameter change transforms the chip shape from unfavorable V-shape to more favorable forms, improving chip control and extending tool life.
2Device complexity
If the threading tool uses a single cutting edge throughout all passes, then the tool structure is simple, but the cutting edge suffers concentrated wear that reduces tool longevity
Solution Approach 1:
The patent applies segmentation by dividing the cutting function across multiple cutting edges. The threading tool includes a first cutting edge for the first oscillating pass and a second cutting edge for the second oscillating pass. This segmentation distributes the wear load, preventing any single cutting edge from suffering concentrated wear and extending overall tool longevity.
3Reliability
If the oscillation frequency is increased significantly, then chip breaking is improved, but the machining process becomes more complex and requires higher precision control
Solution Approach 1:
The patent applies partial action by implementing frequency increase only in the second oscillating pass rather than throughout the entire machining process. The frequency is increased by at least 50% from the first to the second pass, providing sufficient chip breaking improvement without requiring excessive precision control across all passes. This partial application balances effectiveness with manageable complexity.
Data Source
AI summary
A machining method, for a CNC-lathe for forming a predefined thread in a work piece, includes the steps of: rotating the metal work piece around a rotational axis thereof; moving a threading tool along a longitudinal direction through a set of passes, wherein the longitudinal direction is parallel/coinciding to the rotational axis; oscillating the threading tool in a radial direction during a first pass and first frequency, the threading tool moving between a first radial distance (D1) and a second radial distance (D2), (D1) being greater than (D2); oscillating the threading tool in a radial direction during a second pass and second frequency, the threading tool moving between a third radial distance (D3) and a fourth radial distance (D4), (D3) being greater than (D4) and smaller (D1), and (D4) being smaller than (D2); and during a last pass moving the tool without oscillation in the radial direction.