Open Eye Needle Single-Thread Lock Stitch Mechanism
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Solution Overview
Problem
Existing sewing machines struggle to form single-thread locked handstitches with a thread capturing open eye needle, as the arrangement of components within the sewing machine bed is constrained, making it difficult to achieve accurate and stable stitching, especially in quasi-handstitch applications like pinpoint/saddle stitches, and the stitch length and inter-stitch pitch cannot be set freely.
Innovation Solution
The sewing machine employs an open eye needle with a thread capturing open eye that performs a linear reciprocating motion, a shuttle hook for half-turn rotations, and a thread draw-out actuator for reciprocating motion, in collaboration with a feed dog for elliptical motion, allowing the sewing thread to be captured and the stitch length and inter-stitch pitch to be adjusted, enabling the formation of single-thread locked handstitches on both the front and back surfaces of the fabric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thread capturing open eye needle is used to form single-thread locked handstitches, then the stitch accuracy and stability are improved, but the device complexity increases due to the need for additional components like shuttle hook and thread draw-out actuator
Solution Approach 1:
The patent implements nesting by placing the bobbin case inside the shuttle hook, creating a compact integrated structure. The thread draw-out actuator is also integrated into the existing mechanism space, allowing multiple functional components to occupy overlapping spatial volumes and reducing overall device complexity while maintaining stitch accuracy
Solution Approach 2:
The shuttle hook serves multiple functions: it carries the bobbin case, forms the stitch loop, and works with the thread draw-out actuator to create the locked handstitch effect. This multi-functionality reduces the need for separate dedicated components, thereby managing device complexity while achieving precise stitching
2Productivity
If the stitch formation is performed in the inner space of the sewing machine bed, then the productivity is improved by enabling continuous sewing, but the area available for component arrangement is reduced
Solution Approach 1:
The patent utilizes the vertical dimension within the machine bed by positioning the needle bar vertically and arranging the shuttle hook and bobbin case in the horizontal plane below the needle level. This three-dimensional spatial arrangement allows stitch formation to occur within the confined machine bed space while maintaining continuous sewing capability and high productivity
Solution Approach 2:
The nested arrangement of the bobbin case within the shuttle hook maximizes space utilization in the limited machine bed area, allowing multiple functional components to coexist in a compact configuration that enables continuous high-speed stitching
3Volume of moving object
If the open eye needle and shuttle hook are arranged within the limited machine bed space, then the compactness is improved, but the ease of operation deteriorates due to restricted access for thread guidance and tensioning
Solution Approach 1:
The patent introduces a thread guide that acts as an intermediary component, facilitating thread passage from the spool through the needle and into the shuttle hook area. This mediator component makes thread handling easier despite the compact arrangement, improving ease of operation while maintaining compactness
Solution Approach 2:
The threading path is segmented into distinct sections with dedicated guide points at each stage, allowing the operator to guide the thread through a series of manageable steps rather than attempting to navigate the entire compact mechanism at once, thereby improving accessibility despite limited space
Data Source
Figure 1
Figure 2
Figure 3(A)
AI summary
A sewing thread (20) can be captured certainly with a thread capturing open eye (13a) of an open eye needle (13) and the stitches are formed in the inner space of a sewing machine bed (3). A handstitch and a locked stitch are formed, respectively, on the front surface and the back surface of a fabric workpiece (21) as a skip stitch set through cooperation of the open eye needle (13), a shuttle hook (200) and a thread draw out actuator (401). A feed dog (601) feeds the fabric workpiece by a stitch length (P1) for handstitch during a first stroke of the open eye needle (13), and feeds the fabric workpiece by an inter-stitch pitch (P2) between the handstitches during a second stroke of the open eye needle (13).