Vibrating Densitometer Inner Surface Raised Portions

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Solution Overview

Problem

Existing vibrating densitometers face challenges in achieving sufficient resonant frequency mode separation due to design tolerances, leading to impractical density measurements, particularly when trying to distinguish between closely spaced three-lobed radial vibration modes, which often results in low product yield and precision issues during manufacturing.

Innovation Solution

The use of wire electrical discharge machining (EDM) to precisely cut raised portions on the inner surface of the vibrating member, allowing for increased frequency separation between desired and undesired vibrational modes, while maintaining a cylindrical outer shape, thereby enhancing the accuracy of density measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional grinding methods are used to separate vibrational modes, then manufacturing complexity is reduced, but manufacturing precision and frequency separation are insufficient

Engineering Contradiction:
Improvefrequency separationVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical grinding methods with wire electrical discharge machining (EDM). This substitution enables precise cutting of raised portions on the inner surface of the vibrating member, achieving the required frequency separation between vibrational modes while maintaining manufacturing feasibility. The wire EDM process provides the necessary precision without the limitations of conventional grinding.

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

2Reliability

If design tolerances are relaxed to simplify manufacturing, then ease of manufacture improves, but resonant frequency mode separation becomes insufficient

Engineering Contradiction:
Improvemode separation reliabilityVSAvoidmanufacturing difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the manufacturing parameters by adopting wire EDM technology, which enables tight tolerances and precise dimensional control. This parameter change allows for the creation of raised portions with specific dimensions and positions on the inner surface, ensuring reliable frequency separation while maintaining ease of manufacture through automated precision machining.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If precision cutting methods are used to improve frequency separation, then measurement accuracy improves, but productivity decreases

Engineering Contradiction:
Improvedensity measurement accuracyVSAvoidmanufacturing yield
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by designing and forming the raised portions on the inner surface during the manufacturing process itself, rather than attempting to achieve frequency separation through post-manufacturing adjustments or selective testing. The wire EDM process creates the precise geometry needed for mode separation upfront, ensuring both measurement accuracy and manufacturing productivity.

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 provides improved resonant frequency mode separation, increasing the accuracy of density measurements and maintaining a higher product yield by allowing for precise and repeatable cutting of complex shapes, overcoming the limitations of traditional grinding methods.

Implementation Method 1

If an electric current is provided to the coil, a magnetic field is induced in the vibrating member 12 causing the vibrating member 12 to vibrate.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Conversely, the vibration of the vibrating member 12 induces a voltage in the vibrating sensor 17.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

As the vibrating member 12 vibrates, the fluid contacting the vibrating member's wall vibrates along with the vibrating member 12. The added mass of the fluid contacting the vibrating member 12 lowers the resonant frequency.

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP2901132B1A vibrating densitometer with an improved vibrating member
Publication Date: 2017.08.23 MICRO MOTION INC
  • EP2901132B1 patent drawingFigure 1
  • EP2901132B1 patent drawingFigure 2~3
  • EP2901132B1 patent drawingFigure 4

AI summary

A vibrating member (500) for a vibrating densitometer (800) is provided. The vibrating member (500) includes an inner surface (531) with one or more arcuate portions (730). The inner surface (531) of the vibrating member (500) also includes one or more raised portions (530) sized and located to increase a frequency separation between a resonant frequency of a desired vibrational drive mode and a resonant frequency of one or more undesired vibrational modes.