Lightweight Plastic Tube Structure with Expanded Soft Layer

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Solution Overview

Problem

Conventional plastic tube structures used in construction sites are excessively heavy, making handling difficult and requiring significant strength for annular squeezing, while also being costly and prone to defects.

Innovation Solution

A method involving the use of an extruded substrate made of non-expanded, anti-abrasive rigid plastic and an outer layer of expanded soft plastic, with an expanding additive added to the soft plastic material to reduce weight and enhance porosity, allowing for a lightweight tube with high strength and compact inner surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If conventional plastic tube structures with rigid reinforcement are used, then strength for annular squeezing is maintained, but weight becomes excessive making handling difficult

Engineering Contradiction:
Improvetube weightVSAvoidstrength to annular squeezing
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent applies porous materials by introducing an expanding additive (such as perlite, vermiculite, or expanded polystyrene beads) into the soft plastic material during extrusion. This creates a cellular or porous structure within the outer layer that significantly reduces density and weight while maintaining structural integrity and strength through the rigid reinforcement substrate.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The patent employs composite materials by combining soft plastic material containing expanding additives with a rigid reinforcement substrate. This composite structure integrates the lightweight properties of the expanded soft material with the high strength characteristics of the rigid substrate, achieving both weight reduction and maintained strength for annular squeezing resistance.

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If expanding additives are introduced to reduce weight, then weight decreases by 20%, but manufacturing process complexity increases

Engineering Contradiction:
Improvetube weightVSAvoidmanufacturing process complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The patent merges the expanding additive incorporation step with the existing extrusion process. The expanding additive is mixed into the soft plastic material during the standard extrusion operation, and the subsequent expansion occurs during normal cooling, eliminating the need for separate expansion equipment or additional processing steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The expanding additive performs self-service by automatically expanding within the extruded tube during the normal cooling process. This self-expansion mechanism eliminates the need for external expansion equipment or additional processing steps, maintaining manufacturing simplicity while achieving weight reduction.

Inventive Principle:
Principle #25Self-service

3Weight of moving object

If expanding additives are used to create porous structure, then weight is reduced, but inner surface sleekness and compactness may be compromised

Engineering Contradiction:
Improvetube weightVSAvoidinner surface sleekness
Core Design Contradiction:
Weight of moving objectVSShape

Solution Approach 1:

The patent applies local quality by creating different structural characteristics in different regions of the tube wall. The inner layer adjacent to the rigid substrate maintains a compact, sleek structure suitable for conveying utilities, while the outer layer contains the expanded porous structure for weight reduction. This zoned structure optimizes both surface quality and weight properties.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the tube wall structure into distinct functional zones: an inner compact layer for surface sleekness and utility conveyance, and an outer expanded layer for weight reduction. This segmentation allows each zone to optimize its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

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

The method results in a 20% weight reduction, lower production costs, and improved strength for annular squeezing, while maintaining a compact and sleek inner surface, ensuring safe and reliable operation.

Implementation Method 1

introducing into said soft plastic material expanding means designed to expand thermally said soft plastic material so as to confer to said soft plastic material a lightweight porous structure

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

extruding in said element made of soft plastic material a reinforcement substrate made of rigid plastic material

Methodology Applied
Scientific EffectStructural reinforcement:

Implementation Method 3

This strip, still in the semi-molten state, is then wound around an appropriate tool called 'spindle', which produces a spiral element

Methodology Applied
Scientific EffectSpiral winding:

Implementation Method 4

the latter being welded and, once cooled, forming the tube

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3216580B1Method for making a light plastic material tube structure, for building, industrial and agricultural applications, and light plastic material tube structure thus made
Publication Date: 2020.05.13 MERLETT TECNOPLASTIC SPA
  • EP3216580B1 patent drawingFigure 1~2
  • EP3216580B1 patent drawingFigure 3
  • EP3216580B1 patent drawingFigure 4~5

AI summary

A method for producing a lightweight plastic tube structure (1') in particular for construction sites and industrial and agricultural environments, comprising at least the steps of: a) extruding a starting strip-like element (N1) made of soft plastic material (2); b) extruding in the element made of soft plastic material a reinforcement substrate made of rigid plastic material to form an integral complex constituted by the soft strip-like element and the rigid reinforcement element; c) winding the integral complex still in a semi-molten state around a spindle element so as to produce a composite spiral tube-forming complex, wherein the extrusion step a) comprises the auxiliary step a') of introducing into the soft plastic material an expansion additive designed to expand thermally the soft plastic material so as to confer to the latter a lightweight porous structure having a specific weight lower than that of the starting strip-like element made of soft plastic material.