5-Axis Trochoidal Milling of Complex Channel Cavities

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Solution Overview

Problem

Current computer-aided manufacturing (CAM) systems face challenges in efficiently planning tool paths for machining complex channel-shaped cavities using multi-axis machine tools, particularly in controlling vibrations and ensuring precise removal of material without excessive cutting or gouging, especially in deep cavities with thin walls.

Innovation Solution

The method involves a structured combination of 5-axis flank-machining with adaptive analysis of geometrical data and technological constraints, utilizing a 5-axis-Trochoidal-Channel-Roughing (5-axis TCR) approach that includes symmetry propagation, flank pass production, trochoid generation, incremental steps, and auxiliary movements to calculate efficient cutting tool trajectories that satisfy multiple constraints and prevent collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cutting tool removes material rapidly during rough cutting, then productivity is improved, but the risk of excessive cutting or gouging increases

Engineering Contradiction:
Improvematerial removal rateVSAvoidsurface accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The rough cutting process is segmented into multiple depth levels, where the cutting tool removes material in incremental steps rather than attempting to remove all material at once. This segmentation allows high material removal rates while maintaining precision by controlling the depth of cut at each level.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cutting tool follows a periodic trochoidal path with regular oscillations, creating a rhythmic cutting pattern. This periodic action distributes the cutting load evenly, enabling rapid material removal while preventing excessive cutting forces that could cause gouging or vibrations.

Inventive Principle:
Principle #19Periodic action

2Productivity

If the cutting tool engages deeply with rough material, then productivity is improved, but vibrations and chatter increase

Engineering Contradiction:
Improvematerial removal rateVSAvoidtool stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The trochoidal cutting path creates a periodic engagement pattern where the tool oscillates between deep and shallow cuts. This periodic action reduces continuous vibration buildup while maintaining high material removal rates, as the tool periodically disengages to reduce stress and re-engages to remove material.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The cutting depth and engagement are dynamically adjusted throughout the cutting cycle rather than maintaining constant deep engagement. The trochoidal path naturally varies the cutting depth, creating a dynamic cutting process that reduces vibrations while maintaining productivity.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If the cutting tool is positioned for maximal contact with the surface during finish machining, then manufacturing precision is improved, but the mechanical pressure on thin channel walls increases

Engineering Contradiction:
Improvesurface finish qualityVSAvoidmechanical pressure on channel walls
Core Design Contradiction:
Manufacturing precisionVSStress or pressure

Solution Approach 1:

The finish machining process applies localized contact between the cutting tool and the channel surface, rather than broad contact. This local quality approach allows precise surface finishing while distributing mechanical pressure across different locations and time periods, reducing stress on any single thin wall section.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The cutting tool follows a periodic path during finish machining, creating rhythmic contact with the surface. This periodic action distributes mechanical pressure over time and space, allowing high-precision finishing while reducing cumulative stress on thin channel walls compared to continuous contact.

Inventive Principle:
Principle #19Periodic action

4Productivity

If the cutting tool moves at high speed, then productivity is improved, but the risk of collisions and unwanted tool engagement increases

Engineering Contradiction:
Improvemachining speedVSAvoidcollision-free operation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The trochoidal tool path is pre-calculated to inherently avoid collisions with channel walls and bottom surfaces. The path geometry is designed in advance to maintain safe distances from boundaries while achieving high cutting speeds, eliminating the need for real-time collision detection and correction.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The cutting tool follows a curved trochoidal path rather than straight-line movements. This curvature allows the tool to navigate complex channel geometries smoothly at high speeds, reducing sudden direction changes that could cause collisions or unwanted engagement with channel surfaces.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP2846953B1Automatic method for milling complex channel-shaped cavities
Publication Date: 2021.10.13 HEXAGON TECH CENT GMBH
  • EP2846953B1 patent drawingFigure 1
  • EP2846953B1 patent drawingFigure 2
  • EP2846953B1 patent drawingFigure 3

AI summary

Methods and devices for milling a channel-shaped cavity by a five-axis computer numerical control (CNC) machine by selecting a workpiece to be machined (141,210), determining cutting tool flow along the channel-shaped cavity, determining cutting tool in-depth penetration, determining a trochoid path (815,240), and determining auxiliary movements (144,260).