Protective Disc for Agitator Ball Mill Rotary Union

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Solution Overview

Problem

The sealing of the rotary passage in agitator ball mills poses a risk of damage from grinding media impact or friction, particularly with mechanical seals, necessitating protection to extend the service life of rotary unions.

Innovation Solution

A protective disc is attached to the agitator shaft with radial conveying vanes and a convergent annular gap, ensuring effective protection of the rotary feedthrough and enhancing suspension flow and particle dispersion without obstructing material throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective disc is arranged adjacent to the rotary feedthrough to prevent grinding media from contacting the rotary union, then the service life of the rotary union is extended, but the device complexity increases due to additional components and sealing requirements

Engineering Contradiction:
Improveservice life of rotary unionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective disc is merged with the agitator shaft by attaching it directly to the shaft, combining two functional elements (agitation and protection) into a single integrated structure. This eliminates the need for separate protective components and reduces overall device complexity while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The protective disc serves multiple functions: it protects the rotary union from grinding media impact, acts as a structural support element, and integrates with the agitator shaft for multi-functional operation. This multi-functionality reduces the need for additional separate components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If the protective disc is attached to the agitator shaft, then the position of the protective disc is fixed well without impeding material throughput, but the manufacturing complexity increases due to attachment requirements

Engineering Contradiction:
Improveposition fixation of protective discVSAvoidmanufacturing complexity
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The protective disc is merged with the agitator shaft through direct attachment, creating a unified component that is manufactured and installed as a single unit. This integration simplifies the manufacturing process by eliminating separate attachment mechanisms while ensuring stable positioning.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If conveying vanes are added to the protective disc to enhance suspension flow, then the conveying effect is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvesuspension conveying efficiencyVSAvoidstructure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The conveying vanes are merged with the protective disc as an integrated feature, combining protection and conveyance functions into a single component. This integration adds conveying capability without requiring separate vanes or complex attachment mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The protective disc becomes a multi-functional component that simultaneously protects the rotary union and conveys suspension through the grinding container. This multi-functionality enhances productivity while avoiding the need for additional separate conveying mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Manufacturing precision

If a convergent annular gap is provided between the protective disc and grinding container wall, then coarse agglomerations are broken up and uniform suspension entry is achieved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveuniformity of suspension entryVSAvoidmanufacturing precision requirement
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The convergent annular gap is created by providing a specific local geometry at the interface between the protective disc and grinding container wall. This localized geometric feature achieves uniform suspension entry and agglomeration breakdown without requiring high precision throughout the entire component.

Inventive Principle:
Principle #3Local quality

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 solution effectively prevents grinding media from contacting the rotary union, extends its service life, and facilitates efficient grinding and removal of grinding bodies, enhancing the reliability and operation of the agitator ball mill.

Implementation Method 1

conveying vanes running essentially in the radial direction. The thus generated flow of incoming suspension, first in the radial direction and then past the protective disk in the axial direction

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 2

coarse agglomerations of solid materials in the suspension are additionally broken up by this convergent annular gap, for which purpose the shear stresses within the suspension can be used, which occur when the suspension passes through the convergent gap mentioned

Methodology Applied
Scientific EffectShear stress: Shear Stress

Data Source

PatentEP2484450B2Stirring-typ ball mill
Publication Date: 2020.08.19 LIPP MISCHTECHNIK GMBH
  • EP2484450B2 patent drawingFigure 1~2

AI summary

The agitator ball mill has axial agitator shaft (3) which is connected with the wall (15) of the grinding container (7) via a rotary joint (14). A rotary duct provided adjacent to the rotary joint in container in a state covering the emergency pushbutton (16).