Sewing Machine Threader Single Shaft Mechanism
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Solution Overview
Problem
Conventional sewing machine threaders require two operating shafts and manual dexterity, making it difficult to perform fine movements like zigzag stitches efficiently and increasing the machine's inertia, which complicates the design and increases costs.
Innovation Solution
A threader with a single threading shaft that includes a hook and guiding mechanisms, allowing for vertical movement and rotation to insert and catch threads with one hand, using cam mechanisms and a biasing member to control the threading process, reducing the number of parts and machine inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two operating shafts (threading shaft and slider guide shaft) are used to control the hook mechanism, then the threading operation can be reliably performed, but the inertia of the head portion increases and fine movements cannot be performed at high speed
Solution Approach 1:
The patent merges the functions of the threading shaft and slider guide shaft into a single threading shaft. The threading shaft now directly controls both the vertical movement and rotation of the hook mechanism, eliminating the need for the separate slider guide shaft. This consolidation reduces the number of moving parts and decreases the inertia of the head portion, enabling high-speed fine movements while maintaining reliable threading operation.
Solution Approach 2:
The single threading shaft is designed to perform multiple functions: it controls the vertical movement of the hook mechanism, rotates the hook mechanism by a predetermined angle, and positions the slider pin at the upper end portion. This multi-functional design replaces the specialized functions previously distributed across two separate shafts, reducing system complexity and inertia.
2Reliability
If two operating shafts are used to control the hook mechanism, then the threading operation can be reliably performed, but the number of parts increases and the head portion cannot be made compact
Solution Approach 1:
The patent combines the threading shaft and slider guide shaft into a single threading shaft structure. The threading shaft integrates the functionality of both previous components, including the hook mechanism at its lower end portion and the slider pin at its upper end portion. This merger reduces the number of parts from two shafts to one, simplifying the overall structure and making the head portion more compact.
3Device complexity
If manual placement of thread over the hook is required, then the threading mechanism is simple, but the operator must use both hands to perform threading work
Solution Approach 1:
The patent implements a self-service mechanism where the slider pin automatically guides and places the thread onto the hook during the threading operation. When the threading shaft is lowered, the slider pin moves along the thread and automatically positions it on the hook at the lower end portion. This eliminates the need for manual thread placement by the operator, allowing one-handed operation while maintaining a relatively simple threading mechanism.
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
Enables efficient one-handed threading operations, reduces machine size and cost, and maintains sewing precision during fine movements without slowing down the sewing process.
Implementation Method 1
the threading shaft comprising the slider pin is rotated by a predetermined angle by a cam mechanism including a slider pin
Implementation Method 2
a biasing member disposed between the threading hook and the thread-guiding member
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The present invention provides a threader of a sewing machine in which the entire head portion can be made compact and the operator can perform threading work with one hand. The threader comprises: a threading shaft arranged near a needle bar for moving a supported sewing needle vertically; a threading hook for moving a hook portion in and out of a needle hole; a positioning member for regulating a lowermost position of the threading shaft to a position where the height of the hook portion matches that of the needle hole; a first rotary mechanism for rotating by a predetermined angle near the lowermost point of the threading shaft so that the hook portion is inserted into the needle hole of the sewing needle; and a thread-guiding member for guiding the top thread to the hook portion near the lowermost point of the threading shaft. The threader further comprises a second rotary mechanism for rotating by a predetermined angle so that a thread-catching portion of the thread-guiding member passes through the position of the needle hole of the sewing needle near the lowermost point of the threading shaft, and the first rotary mechanism and the second rotary mechanism rotate the threading hook and the thread-guiding member in opposite directions.