Axisymmetric Stylus Tool Curvature for Reduced Oil Canning

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Solution Overview

Problem

Existing stylus tools for 3-axis CNC manufacturing cause significant 'oil canning' due to large forces and hemispherical forming surfaces, and toolpath calculations are computationally expensive and time-consuming.

Innovation Solution

Development of axisymmetric stylus tools with linearly increasing curvature forming surfaces and efficient toolpath generation methods using a toolpath generation module that considers tool shape, size, and part geometry to minimize 'oil canning' and improve computational efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If hemispherical forming surfaces are used in stylus tools, then the tool can form parts from metal, but significant oil canning occurs due to large forces at contact points

Engineering Contradiction:

Improvepart forming capabilityVSAvoidoil canning

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the geometric parameters of the forming surface from a hemispherical shape to a shape with linearly increasing curvature. This parameter change modifies the force distribution at the contact point, reducing the large forces that cause oil canning while maintaining the part forming capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies curvature modification by designing a forming surface where the curvature increases linearly from the tip along the path length. This curvature profile differs from the constant curvature of a hemisphere and is specifically designed to reduce contact forces and eliminate oil canning effects

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If discrete Minkowski sums are used to generate offset surfaces for toolpaths, then toolpaths can be derived, but the process is computationally expensive and time consuming

Engineering Contradiction:

Improvetoolpath generationVSAvoidcomputational time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces the computationally intensive discrete Minkowski sum algorithm with an analytical mathematical approach. By using the axisymmetric property and linear curvature relationship, the toolpath generation becomes a direct calculation rather than an iterative computational process, dramatically reducing computation time

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12596345B2Forming stylus tool design and toolpath generation module for 3 axis computer numerical control manufacturing processes

Publication Date: 2026.04.07 THE BOEING CO

AI summary

A method of toolpath generation is provided whereby the tool may be any smooth convex axisymmetric shape. The tool includes a tool body extending between a shank and a head. The shank is configured to be mounted in a collet which may optionally rotate. In the case of a stylus tool, the head has an axisymmetric forming surface used to press metal. In the case of a routing tool, the head has cutting surfaces which are enveloped by a smooth convex axisymmetric surface and the tool is used for milling a part. In a least one embodiment the tool is a stylus tool which has a forming surface that has been generated from a portion of a clothoid curve.