Extruded Pre-Stretching Roller Structure for Lighter Universal Mounting

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Solution Overview

Problem

Existing pre-stretching rollers for unwinding apparatuses in wrapping machines are complex, expensive, and require multiple versions for different types of unwinding apparatuses, leading to increased production and stock management costs.

Innovation Solution

A pre-stretching roller with a main body made by extrusion, comprising a first tubular element, a second internal tubular element with longitudinal ribs, and longitudinal vanes connecting them, allowing for easy mounting and reduced machining requirements, resulting in a lighter yet mechanically robust roller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional pre-stretching rollers are manufactured with complex structures and multiple components, then the mechanical strength and reliability are improved, but the manufacturing cost and device complexity increase

Engineering Contradiction:
Improvemechanical strengthVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple traditional roller components (cylindrical body, flanges, mounting features) into a single integrated pre-stretching roller body made from extruded material. This consolidation maintains mechanical strength while reducing assembly complexity and the number of separate parts that need to be manufactured and assembled.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The extruded roller body design incorporates multiple functional features (mounting holes, flange integration, structural reinforcement) within a single component that can be adapted to different unwinding apparatus configurations. This universal design reduces the need for multiple specialized versions while maintaining reliability across different applications.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If traditional pre-stretching rollers require extensive machining operations, then the manufacturing precision is improved, but the production time and manufacturing cost increase

Engineering Contradiction:
Improvedimensional accuracyVSAvoidmanufacturing speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The desired final shape, dimensions, and structural features of the pre-stretching roller are created directly during the extrusion process itself, rather than requiring subsequent machining operations. The extrusion mold is designed to produce the roller with near-net-shape accuracy, eliminating the need for time-consuming post-processing while maintaining manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If multiple versions of pre-stretching rollers are produced for different unwinding apparatus types, then the adaptability is improved, but the stock management complexity and production costs increase

Engineering Contradiction:
Improvecompatibility with different apparatusVSAvoidinventory management complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The standardized extruded roller design incorporates universal mounting features and dimensional specifications that allow the same roller component to be used across different types of unwinding apparatus. This universality enables a single roller design to serve multiple applications, reducing inventory complexity while maintaining adaptability to various apparatus configurations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Strength

If traditional pre-stretching rollers use solid metallic construction, then the mechanical strength is improved, but the weight increases

Engineering Contradiction:
Improvestructural strengthVSAvoidroller weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The extruded roller design implements local quality by strategically positioning structural reinforcement elements, ribs, and flange features only where mechanical strength is actually needed for structural support and mounting. The extruded body has varying wall thicknesses and structural density throughout, providing maximum strength at critical locations while minimizing material usage and overall weight in non-critical areas.

Inventive Principle:
Principle #3Local quality

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 solution enables a pre-stretching roller that is simpler, more economical, and easier to manufacture and install, while maintaining precise and reliable operation, thus reducing production and assembly costs.

Implementation Method 1

The film is stretched before being wrapped on the load since the stretching, or elongation, allows the best use of the film... when the stretching force ceases, the elastic return of the film determines a clamping force on the load

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a main body elongated along a longitudinal central axis and obtained by means of an extrusion process

Methodology Applied
Scientific EffectExtrusion: Extrusion

Data Source

PatentEP4377580B1Pre-stretching roller, method of manufacturing the pre-stretching roller and winding apparatus
Publication Date: 2025.05.14 ROBOPAC SPA
  • EP4377580B1 patent drawingFigure 1~3
  • EP4377580B1 patent drawingFigure 4~6
  • EP4377580B1 patent drawingFigure 7~8

AI summary

A pre-stretching roller (1) of an unwinding apparatus associable to a wrapping machine, comprising a main body (2) elongated and manufactured by an extrusion process of a metal alloy; the main body includes a first tubular element (3) having a cylindrical shape and defining an external cylindrical wall (3a) suitable for interacting with a film; a second tubular element (4) internal to the first tubular element and having a first end (5) provided with a first seat (7) suitable for receiving and coupling with a driving shaft of driving means of the unwinding apparatus and an opposite second end (6) provided with a second seat (8) suitable for receiving and coupling with a supporting pin for fixing the pre-stretching roller to the unwinding apparatus; a plurality of longitudinal vanes (10) which connect the first tubular element to the second tubular element; the second tubular element comprises a plurality of longitudinal ribs (16), each of them being connected to a respective longitudinal vane.