Liquid Silicone Rubber Extrusion with Coriolis Mass Flow Control
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Solution Overview
Problem
Current methods for producing liquid silicone rubber compositions face challenges in maintaining consistent mass flow and quality due to variations in material density and the presence of air bubbles, leading to inefficiencies and increased complexity in batch processes.
Innovation Solution
A manufacturing assembly that includes a preconditioning unit, a primary mass flow meter, an extruder with multiple introduction ports, and a control system to monitor and adjust the mass flow of silicone rubber base material and additives, ensuring accurate proportions and consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If batch processes are used to provide smaller batch quantities of liquid silicone rubber, then flexibility in composition and waste of time/materials is minimized, but productivity and process efficiency are reduced
Solution Approach 1:
The continuous extrusion process is segmented into multiple functional zones along the extruder length, including a preconditioning zone for base material, a deaeration zone for removing air bubbles, and a compounding zone for adding additives. This segmentation allows the system to maintain continuous high productivity while accommodating different composition requirements through controlled material introduction at different stages.
Solution Approach 2:
The system employs dynamic control of material flow rates and additive introduction timing to adapt to different composition requirements. The extrusion process continuously adjusts parameters such as screw speed, barrel temperature, and additive feed rates to optimize both productivity and composition flexibility for different product specifications.
2Productivity
If continuous processes are used to increase productivity, then process efficiency is improved, but quality consistency deteriorates due to problems in metering and feeding
Solution Approach 1:
The system incorporates feedback control through Coriolis mass flow meters that continuously monitor the actual mass flow of liquid silicone rubber entering the extruder. The control system uses this real-time data to adjust pump delivery rates and compensate for density variations, ensuring consistent additive proportions and maintaining quality consistency throughout continuous production.
Solution Approach 2:
The invention replaces traditional volumetric metering pumps with Coriolis mass flow measurement and control systems. This substitution transitions from mechanical volume-based metering to precise mass-based measurement and control, eliminating the quality consistency problems associated with volumetric measurement of materials with variable density.
3Device complexity
If metering pumps with known pumping volumes are used to determine master flow, then device complexity is reduced, but measurement precision deteriorates due to variability in material density and air bubbles
Solution Approach 1:
The system replaces simple volumetric metering pumps with Coriolis mass flow meters that directly measure mass flow rate. This substitution eliminates the measurement errors caused by density variations and air bubble presence, providing accurate mass flow data for control purposes while maintaining relatively simple system architecture.
Solution Approach 2:
The invention changes the measurement parameter from volume (which is affected by density and air bubbles) to mass flow rate using Coriolis effect-based measurement. This parameter change enables accurate flow measurement and control despite variations in material density and the presence of air bubbles in the liquid silicone rubber.
4Adaptability or versatility
If cleaning and switching are performed to accommodate compositions of different type, then adaptability is improved, but device complexity and initial investment increase due to more accessories
Solution Approach 1:
The system maintains continuous extrusion operation when changing composition types by using a build-up/clearance strategy. Different composition batches are continuously processed through the extruder, with the control system managing transition periods where material is gradually introduced and cleared. This approach eliminates the need for complete system shutdowns and extensive cleaning operations, reducing complexity while maintaining adaptability.
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 solution enables continuous production of liquid silicone rubber compositions with high accuracy and flexibility, reducing waste and the need for extensive cleaning and mixing steps, while maintaining quality consistency across varying conditions.
Implementation Method 1
a primary Coriolis mass flow meter downstream of the preconditioning assembly and upstream of the extruder
Implementation Method 2
an extruder device, having a first introduction port adapted for the introduction of silicone rubber base material
Data Source
AI summary
Provided are an assembly and process for the continuous or semi-continuous preparation of addition-crosslinking liquid silicone rubbers and to liquid silicone rubber compositions made therefrom. Also disclosed are articles made from the liquid silicone rubber compositions.