Tool Path Generation with Bend Angle Smoothing

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Solution Overview

Problem

Existing tool path generation methods struggle to maintain a smooth machined surface when dealing with varying bend angles and block lengths, leading to shape errors and inconsistencies, especially when smoothing treatment is applied uniformly across all machining paths regardless of curvature.

Innovation Solution

A tool path generation method that calculates bend angles and inserts imaginary blocks corresponding to these angles to adjust the strength of smoothing treatment, using a 3D Bezier curve approximation to generate a new tool path that optimizes the inward curve amount and maintains surface smoothness by varying the smoothing strength based on bend angle thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If smoothing treatment is applied uniformly across all machining paths, then the machined surface becomes smooth, but shape errors increase and the machined shape deteriorates

Engineering Contradiction:
Improvesurface smoothnessVSAvoidshape accuracy
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent applies smoothing treatment selectively based on local characteristics of the tool path. Specifically, it calculates bend angles at each machining point and applies smoothing only where the bend angle is within a permissible range, rather than uniformly across the entire path. This local differentiation allows smooth surfaces in appropriate areas while preserving shape accuracy in areas with large bend angles.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the smoothing treatment based on varying bend angles along the tool path. By calculating the bend angle at each point and comparing it with a predetermined permissible range, the system adaptively determines whether to apply smoothing at each location, making the smoothing strength variable rather than fixed.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If smoothing treatment is validated based on bend angle threshold, then shape accuracy is maintained, but the machined surface becomes inconsistent due to varying block lengths

Engineering Contradiction:
Improveshape accuracyVSAvoidsurface consistency
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The patent changes the parameter used for smoothing control from a simple bend angle threshold to a combination of bend angle and permissible range comparison. By introducing the concept of a permissible range and comparing the calculated bend angle against this range, the system achieves more consistent surface quality while maintaining shape accuracy.

Inventive Principle:
Principle #35Parameter changes

3Shape

If smoothing strength is increased to ensure surface smoothness, then the machined surface becomes smoother, but the deviation from the desired shape increases

Engineering Contradiction:
Improvesurface smoothnessVSAvoidshape deviation
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent applies different smoothing strengths at different locations along the tool path based on local bend angle characteristics. Areas with small bend angles receive stronger smoothing treatment for surface smoothness, while areas with large bend angles receive no smoothing or reduced smoothing to maintain shape accuracy.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The smoothing strength is dynamically adjusted based on the bend angle at each machining point. The system calculates the bend angle and compares it with the permissible range to determine the appropriate smoothing level, making the smoothing process adaptive rather than uniform.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2634658B1Tool path generation method and tool path generation device
Publication Date: 2019.07.24 MAKINO MILLING MASCH CO LTD
  • EP2634658B1 patent drawingFigure 1
  • EP2634658B1 patent drawingFigure 2A~2C
  • EP2634658B1 patent drawingFigure 3A~3B

AI summary

A method including a bend angle calculation step of calculating a bend angle θ at each connecting point of a broken line which is obtained by successively connecting a predetermined plurality of machining points P1 to P3 by line segments, an approximation curve derivation step of deriving an approximation curve L5 closer to the connecting point the larger the bend angle θ calculated by the bend angle calculation step, and a tool path generation step of generating a tool path PA7 along the approximation curve L5 derived by the approximation curve derivation step.