Stretch Wrapping Dispenser with Selectable Pre-Stretch Rate Wheels

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Solution Overview

Problem

Existing stretch wrapping machines often require offline processes for changing pre-stretch amounts, are costly due to servo motors, or have increased mass and complexity, limiting flexibility in supporting multiple pre-stretch amounts for different loads.

Innovation Solution

A loop drive assembly with multiple pre-stretch rate wheels and a rate selection assembly allows for selective coupling to a packaging material dispenser drive input, enabling different discrete pre-stretch amounts without manual replacement or expensive servo motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If offline manual replacement of pulleys/sprockets is used to vary pre-stretch amount, then multiple pre-stretch amounts can be supported, but machine downtime increases and operational efficiency decreases

Engineering Contradiction:

Improvepre-stretch amount variabilityVSAvoidoperational efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent implements a dynamic pre-stretch system where the ratio between upstream and downstream pre-stretch rollers can be changed online through a selector mechanism. This allows the machine to adapt to different pre-stretch requirements without stopping, resolving the contradiction between versatility and productivity by enabling real-time parameter adjustment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent provides multiple pre-stretch rate wheels (first, second, third wheels) that are pre-configured with different circumferences corresponding to different pre-stretch amounts. The selector mechanism pre-arranges these wheels for quick online switching, allowing the operator to select the desired pre-stretch amount without manual replacement during operation.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If servo motors are used to drive pre-stretch rollers at controlled rotational rates, then precise pre-stretch control is achieved, but system cost increases

Engineering Contradiction:

Improvepre-stretch control precisionVSAvoidsystem cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive servo motors with a mechanical solution using multiple pre-configured pre-stretch rate wheels with different circumferences. This mechanical approach provides sufficient pre-stretch control precision at a lower cost, resolving the contradiction between manufacturing precision and system cost by using simpler, more economical components.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the electronic control system (servo motors) with a purely mechanical solution involving a selector mechanism that physically connects the drive roller to different pre-stretch rate wheels. This mechanical substitution achieves the desired pre-stretch control without the complexity and cost of electronic actuators.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If servo motors are used to drive pre-stretch rollers, then pre-stretch control is improved, but dispenser mass increases leading to higher forces during rotation

Engineering Contradiction:

Improvepre-stretch control precisionVSAvoiddispenser mass

Core Design Contradiction:

Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent eliminates heavy servo motors and replaces them with lightweight pre-configured pre-stretch rate wheels of different circumferences. This mechanical approach maintains pre-stretch control precision while significantly reducing the moving mass of the dispenser, resolving the contradiction between control precision and weight.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Adaptability or versatility

If pulleys/sprockets are replaced to vary pre-stretch amount, then multiple pre-stretch amounts can be supported, but maintenance complexity and time requirements increase

Engineering Contradiction:

Improvepre-stretch amount variabilityVSAvoidmaintenance time

Core Design Contradiction:

Adaptability or versatilityVSEase of repair

Solution Approach 1:

The patent implements an online selector mechanism that allows dynamic switching between different pre-stretch rate wheels during machine operation. This eliminates the need for offline replacement and maintenance of pulleys/sprockets, resolving the contradiction between adaptability and maintenance time by enabling real-time parameter changes without mechanical intervention.

Inventive Principle:

Principle #15Dynamics

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

Enables reliable, cost-effective, and low-maintenance support for multiple pre-stretch amounts, improving operational efficiency and flexibility in wrapping operations.

Implementation Method 1

a friction drive system including a drive roller, a first pre-stretch roller, and a second pre-stretch roller, the friction drive system configured to drive the first and second pre-stretch rollers at a predetermined ratio of rotational rates

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP4010255B1Stretch wrapping machine supporting multiple discrete pre-stretch amounts

Publication Date: 2025.08.27 LANTECH COM LLC

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AI summary

A packaging material dispenser of a stretch wrapping machine supports multiple discrete amounts of pre-stretch in a reliable and cost-effective manner in part by incorporating a loop drive assembly with multiple pre-stretch rate wheels capable of being used to drive a driven wheel associated with a pre-stretch roller at different discrete rates of rotation relative to another pre-stretch roller.