Sealing Wire Control System for Fatigue Reduction

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Solution Overview

Problem

Conventional packaging machines using heated wires for sealing plastic film face issues with temperature control, leading to wire fatigue and failure due to frequent current impulses and heat buildup, especially as machine speed increases, resulting in premature wire breakdown and productivity losses.

Innovation Solution

A closed-loop feedback control system that monitors the expansion and contraction of the sealing wire, adjusting the current input to maintain a consistent wire length and reduce stress, using proximity sensors and a programmable logic controller to vary current based on usage and machine operation modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If current is continually supplied to the wire to maintain temperature, then sealing function is maintained, but wire temperature build-up causes fatigue and failure

Engineering Contradiction:
Improvewire lifeVSAvoidwire temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent implements periodic action by supplying current to the wire in controlled impulses rather than continuously. The controller activates current delivery during sealing operations and deactivates it during non-operational periods, allowing the wire to cool between use cycles. This periodic current supply pattern prevents continuous temperature accumulation while maintaining sealing capability when needed.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent employs feedback mechanisms where sensors monitor wire temperature and machine operational status, providing real-time information to the controller. The controller adjusts current delivery based on this feedback, reducing or eliminating current when the wire is not needed for sealing, thereby preventing temperature build-up during idle periods while maintaining operational performance when required.

Inventive Principle:
Principle #23Feedback

2Productivity

If machine speed increases, then productivity improves, but current impulse frequency increases causing wire fatigue

Engineering Contradiction:
Improvemachine speedVSAvoidwire fatigue
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies dynamics by making the current delivery system adaptive and responsive to changing operational conditions. The controller dynamically adjusts current impulse frequency and duration based on real-time machine speed and sealing requirements. When machine speed increases, the system optimizes current delivery parameters to match the accelerated pace while preventing excessive heat accumulation, thereby maintaining wire reliability across varying productivity levels.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from speed sensors and temperature monitors to continuously adjust current delivery parameters. When machine speed increases, the feedback loop detects the change and modifies current impulse characteristics accordingly, ensuring that current frequency and duration are optimized for the higher speed condition without causing wire fatigue or overheating.

Inventive Principle:
Principle #23Feedback

3Productivity

If current impulse frequency increases with machine speed, then sealing operations keep up with machine pace, but wire temperature build-up accelerates

Engineering Contradiction:
Improvesealing rateVSAvoidtemperature build-up
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent implements periodic action through controlled current impulses that are periodically activated during sealing operations and deactivated during non-operational periods. This periodic pattern allows the wire to cool between use cycles, preventing continuous temperature accumulation even as sealing operations proceed at high speed. The timing and duration of these periodic impulses are optimized to match sealing requirements while managing temperature.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts current impulse parameters including frequency, duration, and amplitude based on real-time operational conditions and temperature feedback. When machine speed and sealing rate increase, the controller optimizes current delivery parameters to maintain sealing effectiveness while preventing excessive temperature build-up through adaptive control strategies.

Inventive Principle:
Principle #15Dynamics

4Manufacturing precision

If wire is heated to high temperature for sealing, then sealing quality improves, but wire becomes more susceptible to breakage

Engineering Contradiction:
Improveseal appearanceVSAvoidwire strength
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent applies periodic action by delivering current in controlled impulses rather than continuously, allowing the wire to be heated to sealing temperatures only when needed and then cooled during non-operational periods. This periodic heating pattern enables the wire to achieve high temperatures for quality sealing while preventing continuous thermal degradation that would weaken the wire structure.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system uses temperature feedback to precisely control current delivery and maintain wire temperature within optimal ranges for sealing. The feedback mechanism ensures the wire reaches sufficient temperature for quality seal formation while preventing excessive temperature excursions that would compromise wire strength and integrity.

Inventive Principle:
Principle #23Feedback

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 system extends the life of the sealing wire by reducing fatigue and preventing premature failure, ensuring consistent sealing performance and minimizing downtime by automatically adapting to changing machine conditions.

Implementation Method 1

Current is supplied to the wire to heat the wire to a high temperature in order to effect the seal and cutting operation

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 2

The feedback mechanism monitors both the actual current passing through the wire, and the length of the sealing wire

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP1967038B1Improved hot wire control apparatus and method
Publication Date: 2010.10.13 SHANKLIN CORP
  • EP1967038B1 patent drawingFigure 1
  • EP1967038B1 patent drawingFigure 2
  • EP1967038B1 patent drawingFigure 3

AI summary

Control system and apparatus for controlling current input to an electrical resistance element such as a seal wire. The system and apparatus of the present invention is a closed loop feedback modification to conventional systems, and takes advantage of the inherent expansion of the seal wire as it is heated. The feedback mechanism monitors both the actual current passing through the wire, and the length of the sealing wire, and adjusts the current applied to the wire, responsive to those monitored inputs. The usage of the sealing machine is also monitored and the application and amount of current flowing to the wire is varied based on this usage.