Composite Sheet Production Necking Reduction

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Solution Overview

Problem

The existing methods for producing composite sheets with stretchability face challenges in matching the width dimensions of sheets with high and low stretchability, due to necking issues caused by transportation tension, especially when the high-stretchability sheet is extended and transported to a joining roll, leading to mismatches and irregular basis weights in non-woven fabrics.

Innovation Solution

The method involves extending the high-stretchability sheet between upstream and downstream rolls with differing peripheral speeds, where the downstream roll both extends and joins the low-stretchability sheet, eliminating the need for separate transportation and reducing necking by adjusting roll arrangements and using an S-shaped looping configuration to minimize tension load intervals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the first sheet is extended and transported to a joining roll on a downstream side, then the composite sheet can be produced with stretchability, but considerable width shrinkage (necking) occurs due to tension for transportation

Engineering Contradiction:

ImprovestretchabilityVSAvoidwidth dimension

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent merges the extending function and joining function into a single downstream roll. The downstream roll both extends the first sheet in the longitudinal direction and joins the second sheet to it, eliminating the separate transportation step that causes necking. This integration resolves the contradiction by maintaining stretchability while preventing width shrinkage.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the harmful tension force from the system by eliminating the transportation path between separate rolls. By having the downstream roll perform both extending and joining functions simultaneously, the tension that would otherwise cause necking is removed from the process.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of manufacture

If the first sheet is transported while maintaining extended state, then the joining process can be completed, but the width dimension mismatch between first sheet and second sheet increases

Engineering Contradiction:

Improvejoining processVSAvoidwidth dimension matching

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

By combining the extending and joining operations at the downstream roll, the patent eliminates the transportation phase that causes width dimension mismatch. The first sheet is extended and the second sheet is joined in the same operational zone, ensuring proper width matching without the necking that would occur during separate transportation.

Inventive Principle:

Principle #5Merging (Combining)

3Length of moving object

If the length of the portion bridged between upstream rolls and downstream rolls is long, then the transport path is extended, but considerable necking occurs while extending the first sheet

Engineering Contradiction:

Improvetransport pathVSAvoidwidth dimension

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent shortens the bridged portion length by merging the extending and joining functions at the downstream roll. The first sheet is extended and joined in the same zone, eliminating the long bridged portion that would otherwise cause significant necking during transportation.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively alleviates width dimension mismatches between sheets, reduces necking, and enhances the production of composite sheets with consistent stretchability for absorbent articles like diapers, ensuring better fit and performance.

Implementation Method 1

extending the first sheet in the longitudinal direction of the first sheet, while transporting the first sheet in the longitudinal direction of the first sheet with the first sheet being in contact with an upstream roll and a downstream roll that rotate adjacent to each other, by providing a difference in peripheral speeds between the upstream roll and the downstream roll

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

joining the second sheet to a portion of the first sheet in an overlapped manner, the portion being in contact with the downstream roll in the extended state

Methodology Applied

Scientific EffectHeat sealing:

Data Source

PatentUS9067396B2Method of producing composite sheet, method of producing absorbing article using composite sheet and apparatus that produces composite sheet

Publication Date: 2015.06.30 UNI CHARM CORP

AI summary

A method of producing a composite sheet includes joining a first sheet in which stretchability in a longitudinal direction of the first sheet is developed by being subjected to a drawing process in the longitudinal direction and a second sheet having stretchability in a longitudinal direction of the second sheet that is lower than the stretchability of the first sheet. The longitudinal directions are aligned with each other. The first sheet is extended in the longitudinal direction, while transporting the first sheet in the longitudinal direction with the first sheet being in contact with an upstream roll and a downstream roll that rotate adjacent to each other. The second sheet is joined to a portion of the first sheet in an overlapped manner, the portion being in contact with the downstream roll in the extended state.