Vertical Agitator Shaft Startup via Bushing Recess

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Solution Overview

Problem

Vertical agitator ball mills face difficulties in starting due to the high weight of dense grinding media, leading to increased costs and energy requirements, as existing solutions often resort to oversized drive motors.

Innovation Solution

The agitator shaft with grinding elements is raised using a bushing with a recessed bolt system, allowing for reduced axial force through a sloped recess design, enabling easier startup without moving the drive motor, and utilizing a restraining device for controlled lowering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drive motor is oversized to handle the high weight of dense grinding media, then the ball mill can be started reliably, but the production costs and energy requirements increase significantly

Engineering Contradiction:
Improvestartup reliabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The agitator shaft is raised to a higher position before starting the grinding process. This preliminary action reduces the amount of grinding media that needs to be accelerated during startup, thereby reducing the starting torque requirement and allowing for a smaller, more economical drive motor while maintaining reliable operation

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the drive motor is oversized to handle the high weight of dense grinding media, then the ball mill can be started reliably, but the energy requirement during production increases significantly

Engineering Contradiction:
Improvestartup reliabilityVSAvoidenergy requirement
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The agitator shaft is raised to a higher position before starting the grinding process. This preliminary action reduces the amount of grinding media that needs to be accelerated during startup, thereby reducing the starting torque requirement and allowing for a smaller, more economical drive motor while maintaining reliable operation

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the recess in the bushing has a steep slope to reduce axial lifting force, then the startup becomes easier, but the axial force required increases

Engineering Contradiction:
Improvestartup easeVSAvoidaxial force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The system uses a dynamic balance between the sloped recess geometry and the lifting mechanism. The bushing with sloped recesses converts rotational motion into axial lifting motion, where the slope angle is optimized to distribute the lifting force over a longer rotational path, reducing the instantaneous axial force requirement while maintaining ease of operation

Inventive Principle:
Principle #15Dynamics

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 method allows for economical and reliable startup of vertical agitator ball mills by reducing the axial force needed to lift the agitator shaft, minimizing energy consumption and production costs compared to traditional solutions.

Implementation Method 1

The recess in the socket has a slope. The greater the slope of the recess, the greater the axial path that the bolt has to cover during the rotary movement. However, as the pitch increases, the axial force required to lift the agitator shaft decreases.

Methodology Applied
Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentEP3060345B1Apparatus and method for starting a stirring ball mill
Publication Date: 2017.05.31 NETZSCH FEINMAHL TECHNIK GMBH
  • EP3060345B1 patent drawingFigure 1
  • EP3060345B1 patent drawingFigure 2
  • EP3060345B1 patent drawingFigure 3~4

AI summary

Described is a device for starting an agitator ball mill, wherein the agitator ball mill has a vertical grinding container. In the grinding container is mounted a vertical agitator shaft on which at least one grinding element is mounted. The grinding container is for the most part filled with grinding elements. When the agitator ball mill starts the agitator shaft can be lifted by the claimed device to allow starting.