Vacuum Pump Rotor Laser Balancing for Complex Surface Machining

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Solution Overview

Problem

Balancing rotors with complex shapes in vacuum pumps, particularly turbomolecular pumps, is challenging due to the need for precise machining to minimize residual imbalance and ensure reliable operation at high speeds.

Innovation Solution

A method involving rough and fine laser alignment to target material removal on complex rotor surfaces, using a translational mirror system and pulsed laser ablation, allowing for precise control of balancing planes and dynamic imbalance reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional machining methods are used for complex rotor shapes, then material removal is possible, but machining precision and accessibility to various points are insufficient

Engineering Contradiction:
Improvemachining precisionVSAvoidcomplexity of rotor shape
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical machining methods with laser ablation technology. The laser beam can precisely remove material from complex rotor shapes without mechanical contact, achieving high machining precision for difficult-to-reach areas while avoiding the limitations of mechanical tool access.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and parameters of the laser beam through optical systems including mirrors with different orientations (first mirror for rough alignment, second mirror for fine alignment). By adjusting beam parameters and using optical redirection, the system achieves precise material removal at various points on complex rotor surfaces.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If multiple points on the rotor are machined to reduce imbalance, then balance quality improves, but alignment precision and accessibility to all required points become difficult

Engineering Contradiction:
Improvebalance qualityVSAvoidalignment precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces optical mirrors as intermediary elements between the laser source and the rotor surface. The first mirror (with translational movement capability) and second mirror (with rotational capability) act as mediators to redirect and precisely position the laser beam at multiple points on the rotor, enabling accurate alignment and material removal at various locations to achieve high balance quality.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs dynamic alignment systems where the first mirror can move translationally and the second mirror can rotate, allowing the laser beam to dynamically adjust its position and angle. This dynamic capability enables precise targeting of multiple points on the rotor surface throughout the balancing process.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If the laser is precisely aligned for material removal, then machining accuracy improves, but the system complexity and alignment time increase

Engineering Contradiction:
Improvematerial removal precisionVSAvoidalignment time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent divides the alignment process into two distinct stages: rough alignment using the first mirror for coarse positioning, and fine alignment using the second mirror for precise positioning. This segmentation allows each stage to optimize for its specific function, reducing overall alignment time while maintaining high material removal precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs rough alignment as a preliminary action before fine alignment. By first establishing approximate beam positioning with the first mirror, the system reduces the search space for the second mirror, thereby decreasing the time required for precise alignment while ensuring accurate material removal.

Inventive Principle:
Principle #10Preliminary 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

This approach achieves high balance quality and extended service life for vacuum pumps by effectively reducing uneven mass distribution and enabling precise machining of complex rotor shapes.

Implementation Method 1

Material removal using a laser is also referred to as laser ablation. In the process, the material of the rotor, in particular the metallic material, is heated locally to such an extent that melt is expelled with evaporation and/or sublimation.

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

the material of the rotor, in particular the metallic material, is heated locally to such an extent that melt is expelled with evaporation

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

melt is expelled with evaporation and/or sublimation

Methodology Applied
Scientific EffectSublimation: Sublimation

Implementation Method 4

the rough alignment is carried out by means of at least one first mirror, which is moved translationally relative to the rotor

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 5

the alignment of the beam is varied, starting from the rough alignment, in order to bring about a targeted removal of the material in the area of the surface section

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3462035B1Method for balancing a rotor of a vacuum pump
Publication Date: 2021.04.07 PFEIFFER VACUUM GMBH
  • EP3462035B1 patent drawingFigure 1
  • EP3462035B1 patent drawingFigure 2
  • EP3462035B1 patent drawingFigure 3

AI summary

Method for balancing a rotor (13) of a vacuum pump, in particular a turbomolecular pump, in which an imbalance of the rotor is determined and material is removed from the rotor by means of a laser (1) depending on the determined imbalance in order to reduce the imbalance, wherein a coarse alignment and a fine alignment are carried out for a beam (d1) of the laser, wherein the coarse alignment comprises aligning the beam onto a surface section (31, 51) of the rotor which is intended for material removal, wherein the coarse alignment is carried out by means of at least a first mirror (10) which is moved translationally relative to the rotor, and wherein in the fine alignment the alignment of the beam is varied starting from the coarse alignment in order to effect a targeted removal of the material in the area of ​​the surface section.