Roller Crusher Startup Sequence Reduces Frame Stress

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Solution Overview

Problem

Roller crushers experience abrupt load spikes and skewing during startup due to uneven material distribution and high initial pressures, leading to potential damage and failure of the equipment's frame and hydraulic system.

Innovation Solution

A startup sequence for roller crushers involves setting a wider gap and reducing feed rate and rotational speed initially, allowing material to pass through the entire length without crushing, then gradually increasing these parameters to build up forces evenly, avoiding load spikes and skewing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the roller crusher starts with high compression forces and normal production parameters, then productivity is improved, but load spikes and skewing occur causing damage to the frame and hydraulic system

Engineering Contradiction:
ImprovethroughputVSAvoidequipment durability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The startup sequence performs preliminary actions by initially setting the gap to a larger value and feeding material at a reduced rate before transitioning to normal production parameters. This preliminary phase allows material to pass through the entire crushing length without excessive force, preventing load spikes and skewing that would otherwise damage the frame and hydraulic system during startup.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If material is fed at high rate from the beginning, then productivity is improved, but uneven material distribution causes skewing and local overload

Engineering Contradiction:
Improvefeed rateVSAvoidgap uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

During the startup phase, the feed rate is deliberately reduced and the gap is set larger to allow material to distribute evenly along the entire crushing length. This preliminary even distribution prevents skewing and localized overload conditions that would occur if high feed rates were applied immediately, thereby maintaining gap uniformity before transitioning to normal production.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the gap is set to minimum value from the start, then interparticle crushing efficiency is improved, but abrupt load bursts damage the roll surface and pins

Engineering Contradiction:
Improvecomminution efficiencyVSAvoidroll surface integrity
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The startup sequence initially sets the gap to a larger value rather than the minimum production gap. This preliminary configuration allows material to pass through without excessive compression forces, preventing load bursts that would damage the roll surface, pins, and studs. After material is evenly distributed, the gap is gradually reduced to the minimum value for efficient interparticle crushing.

Inventive Principle:
Principle #10Preliminary action

4Productivity

If crushing force is applied immediately at startup, then productivity is improved, but the hydraulic system experiences stress and potential failure

Engineering Contradiction:
Improvecrushing outputVSAvoidhydraulic system stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The startup sequence delays application of full crushing force by initially maintaining a larger gap and reduced feed rate. This preliminary phase allows the hydraulic system to acclimate and the material to distribute evenly before full crushing forces are applied, preventing stress and potential failure of the hydraulic components while maintaining eventual 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 method reduces stress on the equipment by gradually increasing loads and ensuring even force distribution, preventing damage and extending the lifespan of the roller crusher and its components.

Implementation Method 1

the movement of the crushing rolls away from each other is controlled with a hydraulic system comprising active hydraulic cylinders and accumulators

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

accumulators which accumulators provide a spring action to handle varied material feed characteristics

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3860765B1Startup sequence for roller crusher
Publication Date: 2023.08.02 METSO OUTOTEC USA INC
  • EP3860765B1 patent drawingFigure 1~2
  • EP3860765B1 patent drawingFigure 3A~3B
  • EP3860765B1 patent drawingFigure 3C

AI summary

System and method for controlling the startup sequence of a roller crusher is disclosed. The roller crusher includes two generally parallel rollers that are separated by a gap where the rollers rotate in an opposite direction. During startup, the gap between the rollers is greater than the gap during normal production and a feeding arrangement is run at a speed that is lower than a normal production feed rate. The rollers are rotated at a predetermined speed that is less than the speed during normal production. Other parameters of the system are set such that material is fed over the entire length of the rollers and the no crushing force is exerted during the startup. The method and system of the present disclosure reduces the amount of stress on the rolls, frame and hydraulic system of the roller crusher.