CB Hook Thread Cutting Mechanism for Simultaneous Upper and Lower Thread Trimming
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Solution Overview
Problem
Existing sewing and embroidery processes often result in upper and lower threads not being optimally positioned at the end of a seam, leading to suboptimal first stitches and potential issues in further processing, both aesthetically and functionally.
Innovation Solution
A method and device utilizing a CB-type hook or CB hook with a lifting magnet actuator and a forcibly guided cam mechanism to simultaneously cut upper and lower threads to the desired length, positioning the loose ends optimally, allowing for a rich knot in the fabric, and minimizing thread jamming risks. The mechanism includes a plurality of superimposed metal sheets for thread catching and clamping, activated via the main shaft's rotation and energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If threads are cut individually using separate hooks and blades as in US Pat. No. 4,365,568, then the cutting mechanism can be simple, but the cutting time increases and thread positioning precision deteriorates
Solution Approach 1:
The patent merges the cutting of upper and lower threads into a single simultaneous operation using one common blade. The CB-type hook captures both threads together, and a single blade cuts both threads at the same time, eliminating the need for separate cutting operations for each thread type.
Solution Approach 2:
The common blade serves as a universal cutting element that can cut both upper and lower threads. The CB-type hook acts as a multi-functional element that can capture and position both thread types simultaneously, reducing the number of specialized components needed.
2Device complexity
If threads are cut without tension holding as in prior art, then the cutting process is simpler, but thread positioning precision and cutting quality worsen
Solution Approach 1:
The patent applies preliminary action by introducing a thread clamping plate that holds both threads under defined tension before the cutting operation occurs. This pre-positioning ensures that when the blade cuts, the threads are already in the optimal position for clean, precise cuts without fraying or misalignment.
3Productivity
If upper and lower threads are cut simultaneously by a single blade as in the invention, then cutting speed increases, but the device complexity increases due to CB gripper mechanism
Solution Approach 1:
The patent combines the functions of capturing upper and lower threads into a single CB-type hook mechanism, and combines the cutting function into a single blade. This merging allows simultaneous cutting of both threads, doubling the cutting speed compared to sequential cutting methods.
4Productivity
If threads are not positioned optimally at end of seam as in conventional processes, then the sewing process is faster, but stitching quality and further processing capability deteriorate
Solution Approach 1:
The thread clamping plate performs preliminary positioning of threads under tension before cutting. This ensures that when the seam ends, threads are already in the optimal position for high-quality stitching continuation, eliminating the need for repositioning operations that would slow down production.
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
This solution ensures high stitching quality, reduces cutting time, and eliminates the need for lateral needle adjustments, enabling efficient thread cutting and embroidering with CB gripper systems and rotary gripper systems, while maintaining optimal thread positioning for seamless continuation.
Implementation Method 1
The unit is driven by coupling it to the main drive train using a lifting magnet that acts as an actuator
Data Source
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AI summary
The method involves moving a lower thread between a thread outlet opening at a bobbin case and a stitching hole by control edges (17a, 17b). The lower thread is guided into a thread storage of thread catchers (19a-19c). An upper thread is gripped by a hook point, and a needle thread and a material thread are splayed. The lower thread guided into the storage and the upper thread gripped by the hook point are pulled out, and the thread catcher is moved to an initial position, and a detachable end of the upper thread is pulled out from a thread cutting unit by a thread lever. Independent claims are also included for the following: (1) a method for sewing or stitching of upper and lower threads (2) a device for executing a method for cutting upper and lower threads.