Adjustable Upper Thread Knife Assembly for Two-Needle Sewing Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Two-needle sewing machines lack flexibility to handle various sewing tasks efficiently, as existing designs require separate upper thread knife assemblies for different needle spacings and do not allow for reliable cutting and guidance of upper threads.
Innovation Solution
A two-needle sewing machine with an upper thread cutter assembly featuring a knife device and counter-knife device that can adjust to different needle pitches, allowing for simultaneous cutting and clamping of upper threads, and a blade spacing adjustment device that self-centers relative to the needle plane, enabling flexible thread management without additional centering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate upper thread knife assembly is provided for each needle spacing value, then reliable cutting of upper threads is achieved, but the device complexity and number of components increases
Solution Approach 1:
The patent implements a single upper thread knife assembly that can universally cut upper threads for multiple needle spacing values (e.g., 32/32, 32/40, 40/40). The knife assembly achieves this through an adjustable positioning mechanism that allows it to be relocated along the needle bar to different spacing positions, eliminating the need for separate knife assemblies for each needle spacing configuration.
Solution Approach 2:
The knife assembly is designed with dynamic adjustability, allowing its position to be changed along the needle bar according to different needle spacing requirements. This dynamic repositioning capability enables the same physical knife assembly to serve multiple functions across different sewing configurations, reducing overall system complexity while maintaining cutting reliability.
2Device complexity
If the knife assembly is fixed in place, then structural simplicity is maintained, but adaptability to different needle spacings is lost
Solution Approach 1:
The knife assembly transitions from a fixed structure to a dynamically adjustable one. It can be repositioned along the needle bar to accommodate different needle spacing values while maintaining a relatively simple overall structure. The adjustment mechanism allows the knife to adapt to various positions without requiring complete structural redesign.
Solution Approach 2:
The knife assembly is designed as a separable, modular component that can be independently adjusted and repositioned. This segmentation allows the knife to be decoupled from a fixed mounting and repositioned along the needle bar, providing adaptability to different needle spacings while keeping each individual component structurally simple.
3Manufacturing precision
If additional centering mechanisms are added after knife spacing adjustment, then precise centering is achieved, but the device complexity increases
Solution Approach 1:
The knife spacing adjustment mechanism is designed to automatically center the knife assembly relative to the needle bar after adjustment. This self-centering capability eliminates the need for separate manual centering operations or additional centering mechanisms, achieving precise positioning while maintaining structural simplicity. The mechanism serves itself by incorporating centering functionality into the adjustment process.
Solution Approach 2:
The centering function is merged with the knife spacing adjustment mechanism rather than being implemented as a separate system. The adjustment mechanism simultaneously accomplishes both spacing adjustment and centering, reducing the total number of components and simplifying the overall structure while maintaining precision.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An upper thread cutter assembly (9) for a two-needle sewing machine has a cutter assembly (10) for cutting at least two upper threads, each corresponding to the stitch-forming components of one of the two needles. A counter-cutter assembly (11) works in conjunction with the cutter assembly (10) to cut the upper threads. The cutter assembly (10) has two individual cutters (12, 13) for each of the upper threads. A cutter spacing adjustment device (20) serves to specify a target distance (A) between the individual cutters (12, 13) perpendicular to a sewing direction (19). The specified target distance (A) can be selected from at least two cutter spacing values. This results in an upper thread cutter assembly that can be flexibly used for different sewing tasks on the two-needle sewing machine. Two-needle sewing machine with this upper thread cutter assembly.