Contoured Vacuum Support for Sheet Machining Stability

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Solution Overview

Problem

Machining operations on unsupported portions of sheets result in spring back, leading to undesirable hole quality and potential drill bit damage, as the sheet compresses and rapidly returns to its original shape, causing alignment and rigidity issues during machining.

Innovation Solution

A machining support system using a porous material with a contoured support surface and vacuum ports to maintain contact between the sheet and the support tool, reducing spring back by distributing vacuum pressure evenly across the sheet, thereby stabilizing it during machining operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the sheet is left unsupported during machining operations, then the machining process is simpler and faster, but the sheet experiences spring back leading to poor hole quality and potential drill bit damage

Engineering Contradiction:
Improvemachining speedVSAvoidhole quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The sheet is pre-positioned on the contoured support surface before machining begins. The vacuum holding mechanism is activated in advance to secure the sheet, preventing spring back during the subsequent machining operations. This preliminary positioning and securing action ensures the sheet remains stable throughout the machining process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A vacuum holding mechanism acts as an intermediary between the machining tool and the sheet. The vacuum system, comprising a vacuum source, contoured support surface, and permeable barrier, mediates the interaction by providing uniform holding force across the sheet surface, preventing deformation while allowing the machining tool to operate effectively.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If a traditional flat vacuum plate is used to hold the sheet, then the sheet is restrained, but unsupported portions still deflect causing spring back and machining issues

Engineering Contradiction:
Improvesheet stabilityVSAvoidhole quality
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The vacuum plate is designed with a contoured support surface that matches the curvature of the sheet. This curved geometry allows the vacuum force to be distributed uniformly across the entire sheet surface, including edges and corners, preventing localized deflection and spring back while maintaining overall sheet stability during machining operations.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The contoured support surface provides different levels of support at different locations on the sheet. Areas requiring greater stability receive enhanced support from the vacuum pressure distribution, while allowing controlled flexibility in areas where machining forces are applied. This localized quality adjustment optimizes both stability and machining precision.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If the sheet is fully restrained during machining, then spring back is prevented, but the machining tool cannot access the sheet surface effectively

Engineering Contradiction:
Improvehole qualityVSAvoidtool access
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The vacuum holding mechanism applies partial restraint to the sheet - enough to prevent spring back and maintain stability, but not so much as to impede tool access. The permeable barrier allows controlled interaction between the machining tool and sheet surface, providing sufficient holding force while maintaining ease of operation.

Inventive Principle:
Principle #16Partial or excessive action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively reduces or eliminates spring back, maintaining the sheet's shape and improving hole quality by ensuring consistent contact and alignment, thus enhancing machining precision and tool longevity.

Implementation Method 1

a vacuum suction device comprising a vacuum suction plate formed by baking a porous material and having a flat suction face for holding a workpiece by suction

Methodology Applied
Scientific EffectVacuum suction: Vacuum

Implementation Method 2

porous material with a contoured support surface and vacuum ports to maintain contact between the sheet and the support tool, reducing spring back by distributing vacuum pressure evenly across the sheet

Methodology Applied
Scientific EffectPorosity: Porosity

Data Source

PatentEP3705227B1Supporting a contoured sheet of material during machining operations
Publication Date: 2023.12.27 THE BOEING CO
  • EP3705227B1 patent drawingFigure 1
  • EP3705227B1 patent drawingFigure 2~3
  • EP3705227B1 patent drawingFigure 4

AI summary

A machining support (102) configured to reduce spring back of a sheet (104) following a machining operation (106) on the sheet (104) is presented. The machining support (102) comprises a porous material (110) with a plurality of surfaces (112) including a support surface (114) having a contour (116) configured to contact and support the sheet (104); sealing material (118) covering each of the plurality of surfaces (112) except the support surface (114); and a vacuum port (120) configured to provide a vacuum (122) to the porous material (110).