Curved Needle Sewing Machine for Goodyear Welt Joining
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Solution Overview
Problem
The GOODYEAR shoe manufacturing method is labor-intensive and costly due to its reliance on manual operations, specialized craftsmen, and high-quality leathers, with significant waste generation and potential stitching flaws leading to quality issues.
Innovation Solution
A sewing machine and method that enable the simultaneous sewing of an upper, insole, and welt without a form, nails, or glue, using a curved needle to create a sturdy two-thread knotted stitch, reducing waste and production time while maintaining quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If manual operations with pliers and multiple craftsmen are used to join upper to insole, then grip and joining strength are improved, but labor cost and production time increase significantly
Solution Approach 1:
The patent replaces the manual mechanical system of pliers and multiple craftsmen with an automated sewing machine system. The sewing machine uses a needle and thread to create strong permanent stitches that join the upper to the insole, eliminating the need for manual gripping and multiple joining operations while significantly reducing production time and labor costs.
Solution Approach 2:
The patent changes the joining method from mechanical gripping and stapling to textile stitching. By using thread penetration and knotting mechanisms, the sewing machine creates bonds that are both strong and flexible, suitable for shoe construction, while automating the process to improve productivity.
2Ease of operation
If upper is cut to larger dimension for pliers grip, then joining capability is improved, but material waste increases
Solution Approach 1:
The patent replaces the pliers-based mechanical system with a needle-based sewing system. The needle can directly penetrate the fabric at the precise location where joining is needed, eliminating the requirement to cut the upper to larger dimensions for gripping. This allows the upper to be cut to the exact required size, minimizing material waste.
3Productivity
If chain stitching is used to attach welt, then stitching speed is improved, but stitching reliability deteriorates due to thread release and shoe deformation
Solution Approach 1:
The patent changes the stitching mechanism from chain stitching to a more reliable stitch formation method. The sewing machine creates interlocking stitches that distribute stress more evenly and resist thread release. This maintains stitching speed while significantly improving reliability and preventing the anomalous arched shape that occurs with chain stitching under flexing loads.
4Manufacturing precision
If multiple operators and machines are used for first group operations, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The patent merges multiple separate operations (positioning, gripping, joining, and trimming) that were previously performed by multiple craftsmen using multiple tools into a single integrated sewing machine operation. The machine performs all these functions in sequence automatically, reducing device complexity and production cost while maintaining manufacturing precision through automated control.
Data Source
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Figure 3
Figure 3A~7
AI summary
The method enables obtaining a semi-finished workpiece (100) to use in construction of a GOODYEAR type shoe. The semi-finished workpiece (100) is constituted by joining, by means of a single ring-stitching (C): an underfoot insole (101) provided on a lower surface thereof with a perpendicular border (102); an open upper (103); a welt (104) having a linear development which is sufficient to form a ring around the upper (103). The ring stitching (C) is realised by means of a sewing machine (M) having a curved needle (4), which enables the welt (104), the upper (103) and the border (102) to be positioned so that the needle (4) crosses them in order with each of the stitches (P) of the ring stitching (C). With the method and the machine (M) actuating it, the semi-finished workpiece is obtained without the aid of forms, nails, stapes, glue and pliers, which are necessary in the prior art methods.