Integrated Anti-Rotation Stop on Thread-Pulling Knife
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Solution Overview
Problem
Existing lockstitch sewing machines face installation space constraints and thread path impairments due to complex anti-rotation mechanisms, particularly with cantilever arms and webs, which hinder thread running and require additional vertical distance.
Innovation Solution
The anti-rotation stop for the bobbin housing is integrated directly onto the thread-pulling knife, eliminating the need for additional cantilever arms or webs, allowing for reduced installation space and improved thread path efficiency by ensuring the thread-pulling knife can absorb forces in the basic position, thus preventing rotation without obstructing the thread run.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a cantilever arm with anti-rotation stop is used to prevent bobbin housing rotation, then the bobbin housing is secured against rotation in the opposite direction, but the cantilever arm takes up installation space between the bobbin case and support plate that is not available for the thread-pulling knife and requires additional vertical distance
Solution Approach 1:
The patent combines the thread-pulling knife and the second anti-rotation stop into a single integrated component. The thread-pulling knife is extended to include a second anti-rotation stop at its end, eliminating the need for a separate cantilever arm. This merging of functions resolves the space conflict by using the same component for both thread cutting and anti-rotation purposes.
Solution Approach 2:
The thread-pulling knife is given multiple functions: it serves both as the cutting tool for the thread and as the carrier for the second anti-rotation stop. This multi-functionality allows the system to maintain anti-rotation security while freeing up installation space that would otherwise be occupied by a dedicated anti-rotation mechanism.
2Stability of the object's composition
If a cantilever arm with anti-rotation stop is used to prevent bobbin housing rotation, then the bobbin housing is secured against rotation in the opposite direction, but the cantilever arm hinders the running of the thread, particularly when the thread-pulling knife is in a thread grasping position
Solution Approach 1:
By integrating the second anti-rotation stop directly onto the thread-pulling knife, the patent eliminates the separate cantilever arm that was obstructing the thread path. The unified design ensures that the anti-rotation function is achieved without the harmful side effect of thread interference.
Solution Approach 2:
The thread-pulling knife with integrated anti-rotation stop moves dynamically with the knife during operation. When the knife pivots to the thread grasping position, the anti-rotation stop随之 moves, automatically clearing the thread path. This dynamic behavior contrasts with the static cantilever arm that permanently obstructed the thread run.
3Stability of the object's composition
If additional vertical distance is provided between support plate and bobbin housing to accommodate cantilever arm, then the anti-rotation mechanism can be installed, but the thread path requires improvement and thread ends remaining on sewing material are longer
Solution Approach 1:
The integration of the anti-rotation stop onto the thread-pulling knife eliminates the need for additional vertical space between the support plate and bobbin housing. This space savings directly allows for a shorter thread path, resulting in shorter thread ends remaining on the sewing material after cutting.
Data Source
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AI summary
The second rotation stop (38) is fastened to the thread-pulling blade (29). A positioning restraint (41) secures the thread-pulling blade in the normal position when the shuttle (19) turns in the opposite direction. In this position the second rotation stop (38) works with the second spool casing stop (40). The second stop is molded-on integrally with the thread-pulling blade. A projection (39) opposite the second stop on the thread-pulling blade, transitions smoothly into the blade body. A deflection mechanism operates with the thread pulling blade drive (49), this causes displacement of the blade from its normal position, into a thread-gripping position, by moving the positioning restraint into a release position. Further mechanical details of the mechanism are provided. The thread pulling blade drive includes an electromagnet.