Rotating Repitching Members for Elastic Member Stretching
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Solution Overview
Problem
Existing methods for stretching and repitching elastic members for attachment to substrates in manufacturing laminates, such as in hygienic disposables, often result in uneven wrinkling and distorted products due to uneven stretching, leading to packaging and appearance issues.
Innovation Solution
A method and apparatus that involves rotating repitching members around a common axis to stretch and repitch elastic members, allowing for even stretching and repitching by varying the speed and distance between repitching members, ensuring consistent application pitch and reducing wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pitch of elastic members is altered to match the substrate pitch, then the speeds of elastic member and substrate are matched, but uneven stretching occurs causing wrinkling and distortion
Solution Approach 1:
The patent applies dynamics by making the repitching members rotatable around a common axis, allowing the system to dynamically adjust the stretching profile. The repitching members can rotate at variable speeds during different phases of the stretching process, enabling precise control over the stretching rate and ensuring uniform deformation of the elastic member while achieving pitch matching with the substrate.
Solution Approach 2:
The patent implements preliminary action by performing repitching and stretching operations before the elastic member is attached to the substrate. The elastic member is pre-stretched and repitched to the target pitch while still in the feed section, ensuring that when it reaches the attachment section, it is already properly positioned and uniformly stretched, preventing wrinkling during attachment.
2Productivity
If repitching and stretching are performed simultaneously, then production efficiency is improved, but control over stretching profile becomes difficult
Solution Approach 1:
The patent applies segmentation by dividing the stretching process into multiple phases controlled by different repitching members. Each repitching member can be independently controlled to perform specific stretching tasks at different stages, allowing simultaneous repitching and stretching while maintaining precise control over the overall stretching profile through coordinated operation of segmented components.
Solution Approach 2:
The patent implements feedback control by monitoring the positions and speeds of repitching members and adjusting their operation to maintain the desired stretching profile. The system can detect deviations in stretching uniformity and automatically adjust the rotational speeds of repitching members to compensate, ensuring consistent results even during high-speed simultaneous repitching and stretching operations.
Data Source
AI summary
The current invention concerns a method and apparatus for stretching and repitching an elastic member for attachment to a moving substrate, the elastic member being stretchable in at least a longitudinal direction and said elastic member in an essential non-stretched condition comprising an initial length along said longitudinal direction, the method comprising the steps of: (1) providing the elastic member in essentially non-stretched condition to a set of repitching members with an initial supply pitch, said set of repitching members comprising at least a first repitching member and a second repitching member, and optionally one or more repitching members arranged between said first and said second repitching member; (2) receiving said elastic members arranged in non-stretched condition between said set of repitching members, whereby the distance between the first and the second repitching member corresponds to the initial length of the elastic member; (3) moving at least said first and said second repitching members following trajectories diverging from each other, thereby stretching said elastic members arranged between the repitching members to an application length which is longer than the initial length and which corresponds to the length of said elastic member in elastically stretched condition, whereby said repitching members are moved with selectively variable velocity when transferring said elastic members to selectively vary the application pitch of said elastic member in stretched condition on said substrate, the variation of the speed of said repitching members determining the application pitch of said elastic member in stretched condition on said substrate, characterized in that during step (3), said set of elastic members are rotated around a common rotation axis while the elastic member is being stretched from the initial length to the application length.Additionally, the invention concerns a method and apparatus for stretching and repitching an elastic member for attachment to a moving substrate whereby the elastic members are held by repitching members, which are rotated at an essentially constant rotational speed around rotation axes in trajectories, said trajectories being defined by having a different radial distance from the rotation axis to the repitching member rotating around said rotation axis at the application position where the elastic member is attached to the substrate, than at the initial position where the elastic member is received by the repitching members, thereby changing the pitch of the elastic members.