Turbine Blade Clamping Device Eccentric Alignment

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Solution Overview

Problem

Current clamping devices for milling machines, particularly those used for turbine blades, face challenges in ensuring reliable rotational symmetry and precise alignment, often requiring additional processing steps and being unsuitable for various blank shapes and sizes, leading to issues with orientation permutation and inefficient machining.

Innovation Solution

The clamping device features an eccentrically arranged formation on a transverse yoke between clamping jaws, allowing provisional fixation and reproducible alignment via taper pins, with pivotable clamping jaws and a modular structure to accommodate different blank shapes, enabling secure clamping without pre-machining clamping surfaces and ensuring consistent orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If standard two-jaw chuck central clamps are used, then the clamping structure is simple, but the blank cannot be reliably clamped in a rotationally symmetrical manner and orientation cannot be fixed

Engineering Contradiction:
Improveclamping structureVSAvoidrotational symmetry and orientation
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by providing at least one off-center projection on the transverse yoke that engages with a corresponding off-center recess in the blank. This asymmetric feature prevents rotational permutation of the blank around the axis of rotation, ensuring unique and reproducible positioning. The off-center arrangement creates a mechanical key-lock mechanism that eliminates the 180° rotation problem inherent in symmetric clamping devices.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If clamping surfaces are machined in advance on the blank, then reliable clamping is achieved, but an additional processing step is required and material length is increased

Engineering Contradiction:
Improveclamping reliabilityVSAvoidprocessing steps
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by providing a transverse yoke with projections that can preliminarily fix the blank in the correct orientation before final clamping. The off-center projection engages with the off-center recess to pre-position the blank, ensuring proper alignment is established before the clamping jaws apply full clamping force. This eliminates the need for preliminary machining of clamping surfaces.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent extracts the orientation-fixing function from the clamping surfaces and relocates it to the off-center projection-recess mechanism. By separating the positioning function from the clamping function, the invention allows the blank to be secured in the correct orientation through the off-center features alone, without requiring additional clamping surface machining.

Inventive Principle:
Principle #2Taking out (Extraction)

3Area of stationary object

If the clamping device has a small footprint, then machining accessibility is improved, but the clamping force may be insufficient for significant forces during machining

Engineering Contradiction:
Improveclamping device footprintVSAvoidclamping force
Core Design Contradiction:
Area of stationary objectVSForce

Solution Approach 1:

The patent applies dimensionality change by utilizing the radial dimension (off-center distance from the axis of rotation) to provide mechanical advantage for orientation fixation. The off-center projection-recess mechanism leverages the radial offset to create a torque-based locking effect that prevents rotation, thereby achieving secure positioning in a compact radial space without requiring excessive axial length or clamping force.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2286960B1Clamping device for tensioning a blank of a turbine blade in a processing machine, in particular a milling machine
Publication Date: 2020.05.13 SCHERER ENG
  • EP2286960B1 patent drawingFigure 1
  • EP2286960B1 patent drawingFigure 2~3
  • EP2286960B1 patent drawingFigure 4~7

AI summary

The method involves fixing a blank (2) between clamping bars (7) of a tensioning device (1) for processing the blank, and forming a center hole and a blind hole in end faces of the blank. The center and blind holes are engaged with pencil-shaped molds (16) of the tensioning device during clamping of the blank. The clamping bars are set facing toward side wise clamping surfaces. The blank is pressed by the pencil-shaped molds. A cross bar (15) is moved against spring force from the blank. An independent claim is also included for a tensioning device for tensioning a blank in a processing machine i.e. milling machine, including an opening.