Pocket Milling Toolpaths With TEA-Smoothing for Stable Cutting

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Solution Overview

Problem

Conventional contour-parallel method for generating tool paths in computer-aided manufacturing (CAM) systems for pocket milling does not effectively manage variations in cutting forces, leading to tool chatter, vibration, and dimensional errors due to inconsistent tool engagement, which is challenging to control with existing methods.

Innovation Solution

An algorithm that computes a blend arc radius to smooth tool offsets and maintain a consistent material removal rate (MRR) by adjusting feedrate and tool engagement angle (TEA) within acceptable ranges, replacing partial offsets with trochoidal movements in narrow areas to stabilize tool engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional contour-parallel method is used for generating tool paths, then the tool path generation is simple, but tool engagement varies causing cutting force fluctuations, tool chatter, and dimensional errors

Engineering Contradiction:
Improvetool path generation simplicityVSAvoiddimensional accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent transforms the conventional contour-parallel tool path method by dynamically adjusting parameters including replacing straight offsets with blended arcs, substituting trochoidal movements in narrow areas, and modulating feedrate based on material removal rate calculations. These parameter changes stabilize tool engagement and cutting forces while maintaining manufacturing simplicity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces dynamic control of tool engagement angle (TEA) and material removal rate (MRR) throughout the machining process. By continuously adapting feedrate and tool path geometry based on real-time engagement conditions, the system maintains optimal cutting parameters despite varying pocket geometries and tool positions

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If conventional contour-parallel method is used, then the machining process is straightforward, but cutting forces fluctuate causing tool vibration and chatter

Engineering Contradiction:
Improvemachining process straightforwardnessVSAvoidcutting force stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the material removal rate (MRR) is continuously calculated based on tool engagement angle (TEA), feedrate, and pocket geometry. This feedback loop enables dynamic adjustment of feedrate and tool path parameters to maintain stable cutting forces and eliminate vibration

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary calculation of TEA and MRR before executing each tool path segment. By pre-determining optimal feedrate adjustments and blending radii based on upcoming engagement conditions, the system prevents cutting force fluctuations before they occur

Inventive Principle:
Principle #10Preliminary action

3Productivity

If conventional contour-parallel method is used, then tool path generation is quick, but material removal rate is inconsistent

Engineering Contradiction:
Improvematerial removal efficiencyVSAvoidmaterial removal consistency
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent dynamically adjusts feedrate and tool path geometry to maintain constant material removal rate (MRR) throughout the machining process. By continuously adapting to varying engagement conditions, the system achieves both high productivity and consistent material removal

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention transforms fixed parameter tool path generation into a variable parameter system where feedrate, blending radius, and tool engagement angle are continuously adjusted based on real-time MRR calculations, ensuring consistent material removal while maximizing productivity

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2856267B1Profit milling
Publication Date: 2021.04.07 HEXAGON TECH CENT GMBH
  • EP2856267B1 patent drawingFigure 1~3
  • EP2856267B1 patent drawingFigure 4~5
  • EP2856267B1 patent drawingFigure 6

AI summary

Methods and devices for computer-assisted milling of a pocket region of a workpiece by computing a blend arc radius (1610), where the blend arc radius (1610) is based on a maximal variation of a Tool Engagement Angle (TEA), and smoothing at least one offset (1630), where the smoothing is based on the computed blend arc radius and/or a prior computed blend arc radius with a stepover.