Pre-Stretch Roller Layout to Minimize Film Slippage and Necking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stretch-wrapping machines with pre-stretch assemblies experience issues of film slippage and necking due to the increased effective surface area of downstream pre-stretch rollers, particularly when using low-quality film, which undermines the effectiveness of pre-stretching and film usage.
Innovation Solution
A stretch-wrapping machine with at least three pre-stretch rollers, where the third roller has a greater diameter than the first and second rollers, and the rollers are configured to achieve different linear speeds to minimize slippage and necking by distributing the pre-stretching process across multiple stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a downstream pre-stretch roller with double the diameter of the upstream roller is used to achieve high pre-stretch, then the pre-stretch effectiveness is improved, but the effective surface area of the downstream roller increases, causing film slippage to worsen
Solution Approach 1:
The patent divides the single large downstream pre-stretch roller into multiple smaller rollers arranged in series. This segmentation maintains the cumulative pre-stretch effect while reducing the effective surface area of each individual roller, thereby minimizing film slippage. The film passes through multiple stages of pre-stretching rather than a single stage, achieving the same overall stretch ratio without the slippage problems of a large single roller.
Solution Approach 2:
The patent transitions from a single-dimension approach (one large roller) to a multi-dimensional arrangement (multiple smaller rollers in series). By distributing the pre-stretch function across multiple rollers along the film path, the system achieves the required pre-stretch ratio while each roller operates at a smaller, more controllable surface area that prevents slippage.
2Duration of action of stationary object
If the film is pre-stretched to achieve high containment force, then the longevity of the film roll is extended, but necking of the film increases, requiring more film to adequately wrap the load
Solution Approach 1:
The patent segments the pre-stretching process into multiple smaller stages across several rollers, each providing a portion of the total stretch ratio. This distributed approach reduces the necking effect at each stage compared to a single large-stretch stage, while achieving the same cumulative pre-stretch. The film undergoes progressive stretching rather than abrupt stretching, minimizing width reduction.
Solution Approach 2:
The patent changes the operational parameters by using multiple rollers with controlled rotational speeds to achieve the desired pre-stretch ratio. By adjusting the speed differential between adjacent rollers in a multi-roller system, the system achieves high pre-stretch while minimizing necking, as each roller operates within optimal speed ranges that reduce film deformation.
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 effectively minimizes film slippage and necking while maintaining the desired pre-stretch, ensuring efficient film usage and consistent wrapping performance.
Implementation Method 1
The pre-stretch drive assembly drives the rollers so the downstream pre-stretch roller has a higher linear speed than the upstream pre-stretch roller. The linear speed (alternatively called the tangential speed) of a roller is a function of its diameter and its rotational speed and corresponds to the speed of the film contacting the roller.
Implementation Method 2
The linear speed differential results in the downstream pre-stretch roller imposing a stretching force on the film, resulting in the film stretching after it disengages the upstream pre-stretch roller and travels onto the downstream pre-stretch roller.
Data Source
AI summary
Various embodiments of the present disclosure provide a stretch-wrapping machine with at least three pre-stretch rollers sized, positioned, and otherwise configured to minimize necking and slippage as the film is drawn through and stretched by the pre-stretch rollers before the film is applied to the load.