Absorbent Article Joint Ejection via Web Timing Control
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Solution Overview
Problem
Conventional methods for ejecting absorbent articles in manufacturing lines often result in the unintended ejection of non-defective products along with defective ones, particularly those with joint portions, leading to reduced yield rates due to the difficulty in precisely identifying and removing only the defective articles with joint issues.
Innovation Solution
A method that involves controlling the timing and supply of the continuous web to locate the joint portion at the center of the absorbent articles, using an accumulation device with dancer rollers and sensors to adjust the web tension and speed, allowing for precise ejection of only the absorbent articles with joint portions by positioning the joint at the central portion during the cutting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ejection methods are used to remove defective absorbent articles, then defective articles can be ejected from the manufacturing line, but non-defective articles with joint portions are incorrectly ejected along with defective ones, reducing yield rate
Solution Approach 1:
The system performs preliminary positioning of the joint portion to a predetermined location (central portion of the absorbent article) before the ejection decision is made. By using the accumulation device to advance or retract the continuous web, the joint portion is pre-positioned so that when a defective article is detected, the joint portion is already located at a known position, enabling accurate identification and selective ejection of only defective articles containing joint portions.
Solution Approach 2:
The detection device detects the position of the joint portion and provides feedback to the control device, which then controls the accumulation device to position the joint portion at the predetermined location. This closed-loop feedback system ensures that the joint portion is accurately positioned before ejection, allowing the system to distinguish between defective articles with joint portions and non-defective articles, thereby improving both identification accuracy and yield rate.
2Productivity
If the manufacturing line operates at high speed, then productivity is improved, but it becomes difficult to precisely identify and eject only defective articles with joint portions among rapidly moving absorbent articles
Solution Approach 1:
The accumulation device performs preliminary positioning of the joint portion to a predetermined location before the detection and ejection processes. This pre-positioning action occurs while the manufacturing line operates at high speed, allowing the system to maintain productivity while ensuring that when detection occurs, the joint portion is already at a known, predictable location, thereby maintaining detection accuracy despite high-speed operation.
Solution Approach 2:
The accumulation device acts as an intermediary between the high-speed manufacturing line and the detection/ejection system. It mediates the timing and position of the joint portion, allowing the detection device to accurately identify joint portions even during high-speed operation by ensuring the joint portion is at the predetermined location when detection occurs.
Data Source
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AI summary
A method of ejecting absorbent articles PD of the present invention comprises: a step of providing a joint portion P1 where a trailing end of the continuous web WB is joined to a starting end of a next continuous web WB, a step of controlling a timing of supplying the continuous web WB so as to locate the joint portion P1 at a central portion of the absorbent articles PD in a machine direction MD, based on a length of the continuous web from the joint portion P1 up to a cutting location P2 and a dimension L1 of the absorbent articles PD in the machine direction MD of the continuous web WB; and a step of disengaging only absorbent articles PD having the joint portion P1 and ejecting the absorbent articles PD in the course of the manufacturing line.