Sock Toe Seam Positioning via Fabric Elongation
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Solution Overview
Problem
Existing methods for sewing the toe of tubular textile items, such as stockings, result in seams that are uncomfortable due to their placement on the foot tip, aesthetically undesirable as they are visible, and limited to specific arc-shaped designs, hindering the production of high-quality, comfortable, and aesthetically pleasing products, especially in medical and sports applications.
Innovation Solution
A method and apparatus that involve loading, flattening, and elongating one side of the tubular item to create an unbalanced seam, allowing for the seam to be sewn in a position withdrawn from the toe, utilizing a preparation mold with movable blades and pulling devices to stretch and block the fabric, enabling the seam to be placed on one side of the item, thus avoiding discomfort and visibility issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the seam is placed at the end of the tubular item (traditional method), then the sewing operation is simplified and automated, but the seam becomes visible and uncomfortable on the user's foot
Solution Approach 1:
The end portion of the first side is pulled and elongated before the sewing operation, creating an unbalanced configuration that allows the seam to be positioned away from the toe end. This preliminary action enables the seam to be placed on the body portion of the sock where it is less visible and less uncomfortable.
Solution Approach 2:
The method creates an asymmetric configuration by pulling only the end portion of the first side, creating an unbalanced seam arrangement. This asymmetry allows the seam to be positioned away from the centerline and away from the toe end, improving both aesthetics and comfort while maintaining automated sewing.
2Extent of automation
If the tubular item is flattened to define two fabric edges for sewing, then the sewing operation can be automated, but the seam ends up at the extreme position on the user's foot
Solution Approach 1:
The end portion of the first side is pulled and elongated before flattening and sewing, creating an unbalanced configuration. This preliminary action ensures that when the item is flattened and sewn automatically, the seam ends up in a more favorable position on the body portion rather than at the extreme toe position.
Solution Approach 2:
The pulling action is applied locally to only the end portion of the first side, creating a localized elongation that affects specifically where the seam will be positioned. This local quality change allows the seam to be withdrawn from the toe area while maintaining automated sewing processes.
3Strength
If the seam is made thick and stiff for durability, then the sewing strength is improved, but the seam becomes more uncomfortable and likely to rub on the toes
Solution Approach 1:
By pulling and elongating the end portion before sewing, the method creates extra fabric length that allows the seam to be positioned away from the toe area. This reduces the need for extremely thick or stiff seams, as the seam can be placed in a less critical area where it will not rub on the toes during wear.
Solution Approach 2:
The asymmetric pulling of one side creates an unbalanced seam configuration that positions the seam away from the centerline and away from the toe end. This asymmetric positioning reduces the seam's interaction with the toes, allowing for moderate seam strength without excessive thickness or stiffness.
Data Source
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AI summary
A method and a corresponding apparatus (1) for sewing an open end of a tubular textile item (H) so as to make the toe of a sock or of a leg of a stocking, the method comprising the steps of: arranging at least one preparation mold (3) for sewing, designed to receive a tubular item having an open end (4); loading a tubular item onto the preparation mold; flattening the tubular item on the preparation mold, so as to define a first side (5) and a second side (6) overlapping and facing each other, and provided with a respective end portion (5a; 6a); pulling the end portion (5a) of the first side (5) so that at the open end the end portion of the first side is elongated and longitudinally advanced, with respect to the end portion of the second side, of a length defining a given level of unbalancing; then, by keeping the end portion of the first side pulled, simultaneously blocking the first side and the second side so as to make them as one piece and fix the mutual position thereof; by keeping the first side and the second side blocked, releasing the end portion of the first side and taking the preparation mold out of the tubular item; by keeping the first side and the second side blocked, simultaneously placing the respective end portions of the two sides to sewing devices (70) and sewing them, so as to make a closed toe of the tubular item.