Extruder Filling Control for Elastomeric Compound Mixing

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Solution Overview

Problem

The existing methods for producing elastomeric compounds for tires face challenges in maintaining optimal productivity and quality, particularly due to issues with filling degree control and temperature management in continuous extruders, which can lead to scorching and contamination from anti-stick agents.

Innovation Solution

Implementing a feedback control system that adjusts the production speed of small elastomeric pieces based on real-time measurements of torque and hopper filling levels to maintain the extruder's filling degree within a predetermined range, thereby optimizing productivity and quality, and eliminating the need for anti-stick agents by controlling piece sizes and using a lubricating liquid for improved flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the rotation speed of extrusion screws is increased to improve productivity, then the output increases, but the compound temperature rises too much causing scorching

Engineering Contradiction:
ImproveoutputVSAvoidcompound temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

A feedback control system is implemented that continuously monitors the filling degree of the extruder and automatically adjusts the feed rate of elastomeric compound to maintain optimal operating conditions. This prevents temperature rise and scorching while allowing higher screw rotation speeds for improved productivity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention changes the control parameter from fixed feed rate to dynamic feed rate adjustment based on real-time filling degree measurement. By adjusting the feed rate parameter in response to filling degree variations, the system maintains optimal temperature and mixing conditions while maximizing productivity.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the flow rate of compound is controlled to maintain filling degree, then mixing quality improves, but productivity may be limited

Engineering Contradiction:
Improvemixing qualityVSAvoidproductivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system transitions from static flow rate control to dynamic control where the feed rate continuously adapts to maintain optimal filling degree. This dynamic adjustment allows the system to operate at maximum productivity while preserving mixing quality through real-time optimization of flow conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The feedback control system monitors filling degree and adjusts feed rate accordingly, enabling the system to maintain optimal mixing conditions dynamically. This allows productivity to be maximized at each moment while preserving mixing quality through continuous optimization rather than being constrained by fixed flow rate limits.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If small pieces of elastomeric compound are fed to the extruder, then mixing efficiency improves, but pieces may pack in the hopper causing flow issues

Engineering Contradiction:
Improvemixing efficiencyVSAvoidflow continuity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

Vibration is applied to the hopper to prevent packing of small elastomeric pieces and ensure continuous flow to the extruder. This mechanical vibration disrupts particle interlocking and maintains flow continuity while allowing small piece sizes for improved mixing efficiency.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The system changes the state of the hopper from static to vibrating, altering the flow characteristics of the small elastomeric pieces. This parameter change prevents packing while maintaining the benefits of small piece feeding for improved mixing efficiency.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If anti-stick agents are used to prevent packing, then flow improves, but compound contamination occurs

Engineering Contradiction:
ImproveflowVSAvoidcompound purity
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The invention converts the potentially harmful effect of packing into a beneficial controlled flow condition through vibration. By using mechanical vibration instead of chemical anti-stick agents, the system improves flow while avoiding compound contamination, maintaining both ease of operation and compound purity.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Vibration acts as an intermediary mechanism to prevent packing and improve flow without requiring chemical anti-stick agents. This physical intermediary achieves the flow improvement goal while avoiding the harmful contamination effect of chemical agents.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enhances the quality and productivity of the elastomeric compounds by maintaining steady operating conditions, preventing scorching, and reducing contamination, while allowing for precise control of the mixing process without the use of powdery anti-stick agents.

Implementation Method 1

real-time measurements of torque and hopper filling levels

Methodology Applied
Scientific EffectTorque measurement: Torque

Implementation Method 2

using a lubricating liquid for improved flow

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2714368B1Method and apparatus for producing tyres
Publication Date: 2015.10.14 PIRELLI TYRE SPA
  • EP2714368B1 patent drawingFigure 1~1c
  • EP2714368B1 patent drawingFigure 2a~3a
  • EP2714368B1 patent drawingFigure 3b~4b

AI summary

An apparatus for producing elastomeric compounds comprises: a device for reducing an elastomeric compound (4) into small pieces (3) of controlled sizes; a device (5) for continuously feeding the elastomeric compound (4) to an inlet (8) of the device (2) for reducing into small pieces (3); a mixing extruder (6) having an inlet opening (18a) operatively connected with an outlet (16) of the device (2) for reducing into small pieces (3); a device for detecting at least one magnitude value (L, C) indicative of the filling degree of the mixing extruder (6). A control unit (26) operatively connected to the device (2) for reducing into small pieces (3) and the detecting device (25), adjusts the operating speed of the device (2) for reducing into small pieces (3) in such a manner as to maintain said indicative magnitude in the neighbourhood of a predetermined value.