Bag Machine Closed Loop Control for Perforation Registration
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Solution Overview
Problem
Existing rotary bag machines face challenges in accurately registering perforations with respect to seals due to variations in tension, film gauge, and machine inconsistencies, leading to inefficiencies and waste, as they primarily rely on open loop control systems that struggle to determine if perforations are made in the intended location.
Innovation Solution
A closed loop control system is implemented in bag machines, incorporating a seal and perforation inspection station with a vision system and camera to detect and adjust the distance between seals and perforations, allowing for real-time monitoring and adjustment to ensure accurate registration, and incorporating a reject mechanism for unacceptable skirt lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open loop control is used in rotary bag machines, then the machine operation is simpler, but the registration accuracy of perforations with respect to seals deteriorates due to variations in tension, film gauge, and machine inconsistencies
Solution Approach 1:
The patent implements a closed-loop control system that uses sensors to detect the actual positions of seals and perforations on the film web, then feeds this information back to the control system. The controller compares detected positions with target positions and automatically adjusts the sealing and perforating stations to correct any registration errors, thereby maintaining high precision despite variations in tension and film gauge.
2Loss of substance
If the distance between seal and perforation is reduced to minimize waste, then material efficiency improves, but the risk of seal being cut off increases
Solution Approach 1:
The closed-loop control system continuously monitors the actual distance between seals and perforations using detection sensors. By providing real-time feedback on the registration accuracy, the system can dynamically adjust the positioning to maintain an optimal distance that minimizes waste while ensuring the perforation never cuts through the seal, thus preserving seal integrity.
3Productivity
If rotary motion is used to continuously process film, then production speed increases, but registration control becomes more difficult due to continuous motion variations
Solution Approach 1:
The patent employs detection sensors that continuously monitor the positions of seals and perforations during high-speed rotary operation. The control system processes this real-time feedback data and dynamically adjusts the positioning of the sealing and perforating stations to compensate for motion variations, enabling both high productivity and precise registration to be achieved simultaneously.
Solution Approach 2:
The patent replaces purely mechanical open-loop positioning with an automated control system that uses electronic sensors and computer-controlled actuators. This substitution allows for real-time detection and correction of registration errors, providing superior precision control compared to traditional mechanical systems while maintaining continuous high-speed operation.
Data Source
AI summary
A bag machine, and method of making bags, has a sealing station a perforating station, and a downstream seal and perforation inspection station, or a perforation detection station and/or a seal inspection station is disclosed. Control of the perforating and sealing stations is preferably closed loop. The seal and perforation inspection station preferably includes a perforation detector that triggers a vision system and/or a camera, and the film is illuminated. Preferably, the inspection station is enclosed in an opaque housing, or the ambient light is otherwise blocked. The seal and perforation inspection station preferably provides an image output a display visible to a user. The vision system preferably includes a perforation location module and/or determines the distance between the seal and perforation. A downstream processing station can be provided, and can have a detected fault input, connected to a fault detect output from the seal and perforation inspection station.