Extrusion Die Projections with Webs for Thermal Insulation

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Solution Overview

Problem

The existing technologies face challenges in preventing the solidification of plastic melt in extrusion die pass-through openings during granulation, leading to blockages and uneven granulate expulsion due to temperature differences between the extrusion die and granulating die plate, resulting in operational disruptions and the need for costly melt pumps.

Innovation Solution

The implementation of nozzle-like projections with a web projecting beyond their inner sides, enclosed by a sealing material, which absorbs displacements and prevents contact with the hot plastic melt, while maintaining a clearance with the granulating die plate to allow for thermal insulation and prevent blockages, using materials like perfluorinated compounds or O-rings for elasticity and low thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the granulating die plate is cooled strongly to prevent solidification of plastic melt, then the plastic melt can be cooled off effectively, but the plastic melt solidifies in the pass-through openings and occludes holes

Engineering Contradiction:

Improvetemperature of granulating die plateVSAvoidoperational reliability of extrusion process

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

A thermal insulation layer is introduced as an intermediary between the granulating die plate and the extrusion die pass-through openings. This insulation layer mediates the thermal interaction, preventing direct heat transfer from the heated extrusion die to the cooled granulating die plate, thereby avoiding melt solidification in the pass-through openings while maintaining effective cooling at the die plate surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system is segmented into distinct thermal zones: the granulating die plate is cooled separately from the extrusion die. The insulation layer creates a thermal boundary that segments the temperature fields, allowing the die plate to be cooled strongly for effective melt cooling while the pass-through openings remain thermally isolated and heated to prevent solidification.

Inventive Principle:

Principle #1Segmentation

2Loss of energy

If a clearance is provided between the granulating die plate and the liner, then thermal transmission is reduced, but displacements due to different thermal expansions still damage the liners

Engineering Contradiction:

Improvethermal energy loss from extrusion dieVSAvoidstructural integrity of liners

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The thermal expansion parameters of the system are managed by allowing relative displacement between the extrusion die and granulating die plate. The insulation layer accommodates differential thermal expansion by changing its compression state, absorbing the dimensional changes without transmitting damaging forces to the liners while maintaining thermal insulation effectiveness.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the front face surface of the lining rests directly on the granulating die plate, then structural support is provided, but displacements between the extrusion die and granulating die plate damage the liners

Engineering Contradiction:

Improvestructural support of linerVSAvoidoperational reliability of extrusion die

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A flexible insulation layer is used instead of rigid direct contact between the liner and granulating die plate. This flexible layer provides both structural support and accommodation for thermal expansion differences, allowing the system to absorb displacements without damaging the liners while maintaining the necessary mechanical support.

Inventive Principle:

Principle #30Flexible shells and thin films

4Productivity

If cooling water is circulated through the cutting chamber before plastic melt leaves the granulating die plate, then the plastic melt is cooled effectively, but the granulating die plate becomes blocked and requires stoppage

Engineering Contradiction:

Improvecooling efficiency of plastic meltVSAvoidstart-up time of extrusion process

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The insulation layer is pre-installed between the extrusion die and granulating die plate before the extrusion process begins. This preliminary action ensures that thermal isolation is already in place, preventing melt solidification in the pass-through openings during start-up, thereby eliminating the need for stoppages and allowing continuous productive operation.

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 solution effectively prevents solidification of plastic melt in pass-through openings, ensuring smooth operations even with different thermal expansions, reducing the risk of blockages and maintaining operational reliability without the need for high-pressure melt pumps, while minimizing thermal transmission and maintaining the longevity of sealing materials.

Implementation Method 1

an elastic sealing material being arranged between a front face surface of the nozzle-like projection and a supporting element joined with the granulating die plate

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

different thermal expansions of the extrusion die heated during operation and the granulating die plate which is comparatively cold in operation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

the free cross section of the holes being larger than the outside circumference of the projections for the contactless reception of the nozzle-like projections in the holes of the granulating die plate by forming a clearance

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS7367792B2Arrangement with an extrusion die of an extruder

Publication Date: 2008.05.06 ECON

AI summary

The invention relates to an arrangement with an extrusion die (1) of an extruder for granulating plastic material with several pass-through openings (4) for allowing the passage of plastic melt, and a granulating die plate (2) with holes (3) arranged on its die face (1′), with the pass-through openings (4) each opening into a separate nozzle-like projection (6) protruding beyond the front die face (1′) of the extrusion die (1), with the free cross section of the holes (3) being larger than the outside circumference of the projections (6) for the contactless reception of the nozzle-like projections (6) in the holes (3) of the granulating die plate (2) by forming a clearance (7), and with an elastic sealing material (10) being arranged between a front face surface (8) of the nozzle-like projection (6) and a supporting element joined with the granulating die plate (2), preferably a holding flange (2′) of the granulating die plate (2). In order to create advantageous conditions it is proposed that the nozzle-like projections (6) comprise a web (12) projecting beyond its face surface (8) at each of its inner sides delimiting the pass-through opening (4).