Dynamic Film Dispensing Control for Non-Square Load Wrapping
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Solution Overview
Problem
Existing pallet stretch wrapping machines face challenges in efficiently wrapping non-square loads due to erratic speed changes, leading to excess packaging material, loose wraps, or material breaks, especially at high wrapping speeds.
Innovation Solution
The apparatus and method involve a film dispenser with a controller that dynamically adjusts the length of film dispensed during each revolution of the dispenser relative to the load, based on real-time sensing of the load's girth and the speed of an idle roller, to maintain a consistent wrap force and prevent material breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high wrapping speeds are used, then productivity is improved, but packaging material breaks and wrapping reliability deteriorate due to erratic speed changes
Solution Approach 1:
The patent applies dynamics by making the film dispensing system adaptable to varying wrapping speeds. The controller dynamically adjusts the film supply rate to match the instantaneous wrapping speed, allowing the system to operate reliably at high speeds without causing material breakage. This is achieved through continuous monitoring of wrapping speed and real-time adjustment of film dispensing parameters.
Solution Approach 2:
The patent implements feedback control by monitoring the actual wrapping speed and using this information to adjust the film supply rate. The controller receives feedback on wrapping speed variations and automatically compensates by adjusting film dispensing to maintain consistent wrap force and prevent material breakage, enabling reliable high-speed operation.
2Adaptability or versatility
If erratic speed changes are used to accommodate non-square loads, then adaptability is improved, but excess packaging material is supplied and manufacturing precision deteriorates
Solution Approach 1:
The system dynamically adjusts film supply based on real-time wrapping speed variations caused by different load geometries. Rather than using fixed speed profiles, the controller continuously adapts the film dispensing rate to match the instantaneous wrapping speed, ensuring precise material length control regardless of load shape. This eliminates excess material supply while maintaining adaptability to non-square loads.
Solution Approach 2:
The feedback mechanism monitors wrapping speed variations that occur when wrapping different portions of non-square loads and automatically adjusts film supply accordingly. This closed-loop control ensures that the film length supplied precisely matches the actual wrapping demand, preventing both excess material usage and material shortages, thereby improving manufacturing precision while maintaining adaptability.
3Adaptability or versatility
If demand rate for packaging material varies during wrapping, then adaptability to different load shapes is improved, but supply rate cannot match demand rate and reliability deteriorates
Solution Approach 1:
The system dynamically adjusts the film supply rate to match the varying demand rate throughout the wrapping cycle. The controller continuously monitors wrapping speed and calculates the instantaneous film demand, then adjusts dispensing parameters in real-time to ensure supply matches demand. This dynamic adaptation prevents both material breakage from insufficient supply and excess material from over-supply, maintaining reliability across varying load shapes.
Solution Approach 2:
The feedback control system monitors wrapping speed variations that reflect changing film demand and automatically adjusts the film supply rate accordingly. When wrapping speed increases (indicating higher demand), the system increases film supply; when speed decreases (lower demand), supply is reduced. This real-time feedback ensures reliable operation by preventing material breakage while adapting to varying load geometries.
4Manufacturing precision
If constant tension control is attempted through feed rate adjustment, then wrap force consistency is improved, but fluctuations occur with large demand rate variations and manufacturing precision deteriorates
Solution Approach 1:
The system dynamically adjusts film feed rate based on real-time wrapping speed to maintain constant wrap force. The controller calculates the required feed rate to achieve target tension at the current wrapping speed, allowing consistent wrap force even at high wrapping speeds. This dynamic adjustment eliminates the inverse relationship between wrap force consistency and productivity that plagued previous systems.
Solution Approach 2:
The feedback mechanism monitors wrapping speed and uses this information to adjust film feed rate for constant tension control. By continuously adapting the feed rate to match actual wrapping conditions, the system maintains consistent wrap force regardless of wrapping speed or load geometry, achieving both manufacturing precision and high productivity simultaneously.
Data Source
AI summary
An apparatus for wrapping a load may include a film dispenser for dispensing a film web including a film dispensing drive. The apparatus may also include a rotational drive system for providing relative rotation between the load and the dispenser during a wrapping cycle. The apparatus may further include a controller configured to operatively couple the film dispensing drive and the rotational drive system such that, for any portion of a revolution of the film dispenser relative to the load during the wrapping cycle, the film dispenser dispenses a selected length of the film web corresponding to the portion of the revolution.