Web Joining Device Crotch Hold Mechanism Crease Prevention
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Solution Overview
Problem
In the manufacturing of absorbent articles like pants-type disposable diapers, the contraction of leg gathers during the web folding process leads to creases at joint portions and the crotch portion floating off, causing defects due to centrifugal forces and interference with ultrasonic horns or anvil rolls.
Innovation Solution
A web joint apparatus with a crotch hold mechanism that stretches the web away from the waistline portions, using a crotch hold bar and restricting units to prevent contraction and ensure proper alignment during the joining process, thereby preventing creases and curling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the web is folded into two in the cross direction with leg gathers at the leg-surrounding portions, then the absorbent article can be formed with leg-surrounding portions, but the vicinity of the leg-surrounding portions contracts in the cross direction causing creases at joint portions
Solution Approach 1:
The patent applies preliminary anti-action by introducing a holding mechanism that prevents the web from contracting in the cross direction before the joining process occurs. The holding mechanism stretches the web in the machine direction, counteracting the contraction force of the leg gathers, thereby preventing crease formation at the joint portions before they can occur during ultrasonic joining.
2Productivity
If the web is conveyed along the outer peripheral surface of the anvil rolls, then the joining process can be performed, but the crotch portion floats off from the anvil rolls due to centrifugal force when the leg gathers contract
Solution Approach 1:
The holding mechanism applies preliminary anti-action by maintaining tension on the web in the machine direction, which prevents the crotch portion from floating off due to centrifugal force. This ensures the crotch portion remains in proper contact with the anvil rolls throughout the joining process, eliminating the reliability issue.
Solution Approach 2:
The holding mechanism performs preliminary action by pre-stretching and positioning the web before it enters the joining zone. This preliminary positioning ensures that the crotch portion is properly aligned and maintained in contact with the anvil rolls, preventing curling and interference with the ultrasonic horn during the subsequent joining operation.
3Quantity of substance
If the crotch portion is heavier than the waistline portions, then the absorber can be properly positioned in the crotch, but the crotch portion is more likely to float off and curl up due to centrifugal force during joining
Solution Approach 1:
The holding mechanism applies preliminary anti-action by creating continuous tension on the web in the machine direction, which counteracts the centrifugal force that causes the heavier crotch portion to float off and curl up. This maintains the proper shape and position of the crotch portion throughout the joining process.
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 solution effectively prevents creases at joint portions and ensures the crotch portion remains aligned, reducing manufacturing defects and ensuring smooth conveyance without curling, thus enhancing the production quality of absorbent articles.
Implementation Method 1
a ultrasonic horn and an anvil roll while the web folded in two are continuously being conveyed
Data Source
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AI summary
A web joint apparatus 200 is configured to join a pair of webs 61, 62 for absorbent article 1 folded in the cross direction CD with reference to a folding line. The web joint apparatus 200 includes: an ultrasonic horn 211 configured to join the paired waistline portions 10; an anvil 222 facing the ultrasonic horn 211 and configured to pinch the intermediate web 6 between the anvil 222 and the ultrasonic horn 211; and a crotch hold bar 240 configured to hold the intermediate web 6 while stretching the intermediate web 6 in a direction in which the crotch portions 20 get away from the waistline portions, when the intermediate web 6 are joined by the ultrasonic horn 211 and the anvil 222.