Flexible Shaft Feedthrough Sealing for Agitator Ball Mills

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Solution Overview

Problem

Existing agitator ball mills face challenges in achieving a reliable seal for the shaft bushing, particularly in large mills, where manufacturing tolerances and shaft movements can lead to leakage and reduced sealing effectiveness.

Innovation Solution

A shaft bushing design featuring a flexible fastening element with compressible and elastic layers, anchored to the end wall or lid via a connection unit, allows for axial and radial mobility of the shaft, accommodating manufacturing tolerances and compensating for shaft deflections, and incorporates a sealing module with interchangeable sealing elements to ensure a secure seal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a rigid shaft feedthrough design is used, then manufacturing precision can be maintained, but the sealing reliability deteriorates due to shaft movements and vibrations

Engineering Contradiction:
Improveshaft feedthrough manufacturing precisionVSAvoidsealing reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies the dynamics principle by transforming the rigid shaft feedthrough into a flexible design. The shaft feedthrough is made flexible to accommodate shaft movements and vibrations while maintaining sealing reliability. This allows the system to adapt to dynamic conditions without compromising the seal, resolving the contradiction between manufacturing precision and sealing reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the physical parameter of the shaft feedthrough from rigid to flexible. By altering the stiffness parameter, the system can now absorb shaft movements and vibrations while maintaining effective sealing. This parameter change enables the shaft feedthrough to maintain both manufacturing precision and sealing reliability under dynamic operating conditions.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If sealing elements are fixed in position, then sealing effectiveness is maintained, but ease of repair deteriorates due to difficulty in replacement

Engineering Contradiction:
Improvesealing effectivenessVSAvoidsealing element replacement ease
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent applies segmentation by dividing the shaft seal assembly into separable components. The sealing elements are made detachable from the shaft feedthrough, allowing them to be removed and replaced independently. This segmentation maintains sealing effectiveness during operation while enabling easy replacement during maintenance, resolving the contradiction between sealing effectiveness and ease of repair.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic accessibility to the sealing elements. While the shaft feedthrough remains installed and functional, the sealing elements can be accessed and replaced. This dynamic design allows the system to maintain both effective sealing during operation and ease of repair during maintenance without requiring complete disassembly.

Inventive Principle:
Principle #15Dynamics

3Reliability

If a flexible shaft feedthrough design is used, then sealing reliability is improved by accommodating shaft movements, but device complexity increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidshaft feedthrough structural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a flexible shaft feedthrough design that uses flexible materials or structures to accommodate shaft movements and vibrations. This flexible design maintains sealing reliability by adapting to dynamic conditions without requiring complex mechanical compensation mechanisms, thus improving reliability while controlling device complexity.

Inventive Principle:
Principle #30Flexible shells and thin films

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 flexible fastening element and modular sealing design enhance the sealing reliability, absorb vibrations, and extend the service life of sealing elements, allowing for easy replacement and adaptation to different sealing configurations, thereby improving the overall sealing performance and maintenance efficiency.

Implementation Method 1

The flexible fastening element is designed as a ring element and is constructed in the axial direction from at least two layers arranged next to one another, wherein at least one layer is compressible and/or elastic.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The flexible fastening element and modular sealing design enhance the sealing reliability, absorb vibrations

Methodology Applied
Scientific EffectVibration absorption: Damping

Data Source

PatentEP3129150B1Strirring ball mill with a shaft feedthrough
Publication Date: 2024.01.03 NETZSCH FEINMAHL TECHNIK GMBH
  • EP3129150B1 patent drawingFigure 1~2
  • EP3129150B1 patent drawingFigure 3
  • EP3129150B1 patent drawingFigure 4

AI summary

The invention relates to a shaft feed-through (2) of a drive shaft (7) of an agitator (6) of an agitating ball mill (1). The agitating ball mill (1) comprises a cylindrical grinding container (3), which is closed on both sides by end walls (4, 5). In the area of one of the end walls, the drive shaft (7) of the agitator (6) is enclosed by a shaft seal sleeve (21) and is guided through a central opening (10) in the end wall (5). The shaft feed-through (2) comprises a sealing module (27) enclosing the drive shaft (7) and the shaft seal sleeve (21) in the area of the central opening (10), which sealing module comprises at least one sealing element (35, 36, 37, 38) for sealing the central opening (10) of the end wall (5) with respect to the drive shaft (7), and a connecting unit (25), to which the at least one sealing element (35, 36, 37, 38) is assigned. The sealing module (27) is anchored to the end wall (5) by way of the connecting unit (25), wherein the anchoring is configured so as to be flexible, and comprises a flexible fastening element (30) between end wall (5) and connecting unit (25).