Web Material Defect Mapping Using Reference Mark Displacement
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Solution Overview
Problem
Current web inspection systems lack reliability in detecting defects, particularly in nonwoven materials, due to material variations and tension-induced positional changes during the production process, leading to inaccurate defect location and increased material waste.
Innovation Solution
A device with a mapping station comprising two modules and a computation module that uses reference marks on the web to track displacement and calculate the final position of defects, accounting for tension-induced deformations, ensuring precise defect location and minimizing material removal errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If visual control with cameras is used to detect defects, then defect detection capability is provided, but measurement precision deteriorates due to inability to differentiate normal material variations from real defects
Solution Approach 1:
The patent introduces reference marks as intermediary elements on the web material that serve as stable reference points. These marks allow the system to track the actual position of defects relative to known references, enabling precise location determination even when visual characteristics are ambiguous. The reference marks act as a mediator between the defect detection system and the final positioning system.
Solution Approach 2:
The patent creates a virtual copy of the web material with reference marks superimposed on the actual web. By tracking the position of these virtual reference marks through the production process, the system can accurately determine defect locations without needing to directly measure every pixel of the web material, thus improving measurement precision while maintaining detection capability.
2Productivity
If mathematical calculations are used to estimate defect position, then processing speed is maintained, but manufacturing precision deteriorates due to web stretching and tension-induced position changes
Solution Approach 1:
The patent implements a feedback mechanism where the actual position of reference marks is continuously monitored and fed back to the positioning system. This real-time feedback allows the system to compensate for web stretching and tension effects, maintaining both high processing speed through automated tracking and high manufacturing precision through continuous position correction.
Solution Approach 2:
The patent applies preliminary action by placing reference marks on the web material before it enters the production process. These pre-positioned marks serve as known starting points that can be tracked throughout the entire production sequence, allowing the system to predict and compensate for position changes before they affect defect location accuracy.
3Ease of manufacture
If defect removal by rejection of finished reel is used, then simplicity of the removal process is maintained, but loss of substance increases due to removal of defective material from the reel or other finished reels
Solution Approach 1:
The patent replaces the mechanical/reliant system of physical reel rejection with an information-based system using reference marks and computational tracking. By substituting the mechanical action of reel rejection with precise positional data from reference marks, the system can identify and remove only the specific defective portions of material without accidentally removing good material from other reels, thus reducing substance loss while maintaining process simplicity through automation.
4Stability of the object's composition
If defect removal by splicing is used, then material continuity is maintained, but loss of substance increases due to large imprecision of defective area causing larger area removal
Solution Approach 1:
The patent applies preliminary action by establishing precise reference marks and their initial positions before the splicing operation. This pre-positioning information allows the splicing system to accurately identify the exact location and extent of defective areas, enabling precise splicing that maintains material continuity while minimizing the removal of sound material surrounding the defect.
Solution Approach 2:
The patent creates a precise virtual copy of the web material with reference marks that tracks the exact position and dimensions of defective areas. This digital copy allows the splicing system to plan and execute precise cuts without physically measuring or guessing the defect boundaries, thereby maintaining material continuity while minimizing substance loss through accurate defect area identification.
Data Source
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AI summary
The present relates to a device for mapping at least one defect in a web of material comprising a mapping station comprises two modules named a first module and a second module and a computation module, the first module being arranged for marking the web with at least one reference mark at a known position, and for determining the initial position of said defect, and the second module being arranged for detecting a new position of the reference mark when said reference mark is read by the said second module, the computation module being arranged for computing a displacement of the reference mark to determine a final position of the detected defect at second station based on the computed displacement of the reference mark. The invention further relates to a system, a method for mapping and a method for removing a defect.