Tear Strip Detection and Web Tension Control in Cigarette Overwrap Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for producing cigarette pack overwraps with integrated tear strips face challenges in accurately detecting and positioning the tear strip, particularly when both are made of transparent film, and struggle to control web tension to prevent creasing due to differing shrinkage behaviors of the tear strip and film, leading to inefficiencies and errors in the manufacturing process.
Innovation Solution
Implementing an electro-optical testing element, such as a line sensor, to monitor the composite material web for crease formation downstream of the connecting station, adjusting web tension automatically to reduce wrinkling by varying the tensile forces applied to the tear strip and film web, and using a dancer system to control these forces, ensuring precise alignment and positioning of the tear strip during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a light barrier sensor unit is used to detect the tear strip position, then the presence of the tear strip can be detected, but the exact position and alignment cannot be precisely determined
Solution Approach 1:
A test strip with contrasting optical properties is introduced as an intermediary element between the transparent tear strip and the sensor system. The test strip serves as a detectable marker that enables precise position measurement without directly interfering with the tear strip's function. The sensor detects the test strip's position, which correlates to the tear strip position, achieving both detection and precision.
Solution Approach 2:
The test strip is designed with different optical properties (contrasting color or transparency) compared to the surrounding film. This optical contrast enables the optoelectronic sensor to distinguish the test strip's position accurately, providing precise positional information for tear strip alignment while maintaining the transparency of the actual tear strip material.
2Ease of manufacture
If the tear strip and film web are stretched to different extents before joining, then connection is achieved, but creases form after incisions due to different shrinkage behavior
Solution Approach 1:
The elongation characteristics of the tear strip and film web are carefully controlled and matched as critical parameters. By adjusting the manufacturing parameters of these components to have similar elongation values, the patent prevents differential shrinkage after incision, thereby avoiding crease formation while maintaining the feasibility of the connection process.
Solution Approach 2:
The patent preemptively addresses the shrinkage issue by selecting and controlling materials with matched elongation properties before the connection and incision processes occur. This preliminary control of material properties prevents the harmful shrinkage effect from occurring in the first place, rather than attempting to correct creases after they form.
3Measurement precision
If laborious sensor training is performed during product change, then threshold values can be adapted, but production time is lost and efficiency decreases
Solution Approach 1:
The test strip is pre-positioned on the film web in a known, consistent location during manufacturing. This preliminary placement creates a predictable, repeatable detection scenario that eliminates the need for laborious sensor training during product changes. The sensor can use fixed threshold values and positioning logic, enabling rapid product changeovers while maintaining detection accuracy.
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
This approach allows for precise detection and positioning of the tear strip, reduces creasing issues by minimizing the difference in elongation values between the tear strip and film web, and enhances the manufacturing efficiency by reducing the need for laborious sensor adjustments during product changes, enabling the production of high-quality cigarette pack overwraps with improved accuracy and reduced errors.
Implementation Method 1
A sensor unit with a light transmitter and a receiver designed as a photodiode is arranged adjacent to one side of the film material in such a way that the light from the light transmitter shines through the film and strikes a reflector arranged adjacent to the other side of the film. The reflector then reflects the light in the direction of the diode
Implementation Method 2
A sensor unit with a light transmitter and a receiver designed as a photodiode
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and a device for producing outer wrappings (11) for packages (10) for items that can be smoked, having a tear-open strip (24) arranged thereon, wherein a continuous tear-open strip (24) is connected to a side (13.1) of a continuous film web (13) to form a composite material web (50) at a connecting station (49). The method is characterized in that the composite material web (50) or individual cuts thereof are monitored downstream of the connecting station (49) in regard to the formation of folds (55) by means of an in particular electro-optical inspecting instrument, preferably a line sensor, and that the web tension of the tear-open strip (24) and/or of the film web (13) at which the tear-open strip and/or the film web is fed to the connecting station (49) is automatically changed in order to counteract a fold formation (55) if the inspecting instrument detects a fold formation (55) or a fold formation (55) that exceeds a specified size.