Thread Cutting Module for Buttonhole Sewing Machine
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Solution Overview
Problem
Existing thread cutting assemblies for eyelet sewing machines often result in manual trimming of thread ends after eyelet production, indicating a lack of reliability in automatic thread cutting.
Innovation Solution
A thread cutting assembly with a designed thread knife and counter-knife that interact within the eyelet stitch area to securely cut protruding thread ends, featuring a compact arrangement of clamping elements and blades with adapted cutting contours to prevent interference and ensure reliable cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thread cutting knife is positioned to cut threads in the eyelet stitch area, then thread cutting reliability is improved, but the clamping elements may impede the cutting operation
Solution Approach 1:
The clamping system is divided into at least two separate clamping elements positioned at different locations. This segmentation allows one clamping element to remain stationary during thread cutting while another moves, preventing interference with the cutting knife and maintaining reliable thread cutting in the eyelet stitch area.
Solution Approach 2:
The clamping elements are designed with different mobility characteristics - at least one clamping element is movable while another remains stationary during the cutting operation. This dynamic arrangement allows the system to adapt during different phases of operation, enabling reliable thread cutting without clamping interference.
2Force
If the clamping elements are positioned to securely clamp the workpiece, then clamping effectiveness is improved, but the thread cutting operation may be impeded
Solution Approach 1:
The clamping function is segmented across multiple elements with different roles. At least one clamping element maintains a stationary position that provides stable clamping force without interfering with the cutting path, while other elements can move to accommodate the cutting operation, thus maintaining both clamping effectiveness and cutting ease.
Solution Approach 2:
The stationary clamping element acts as an intermediary that provides stable clamping force during the cutting operation without directly interfering with the cutting knife's path. This mediator element allows the cutting operation to proceed smoothly while maintaining workpiece security.
3Reliability
If the cutting edge extends into the eyelet stitch area, then thread cutting capability is improved, but the counter-knife may impede eyelet seam formation
Solution Approach 1:
The cutting edge of the counter-knife is designed with non-uniform characteristics - it extends into the eyelet stitch area in specific locations to enable reliable thread cutting, while other portions are positioned to avoid interfering with eyelet seam formation. This localized differentiation allows the counter-knife to perform multiple functions without compromising either thread cutting capability or seam quality.
Data Source
Figure 1
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Figure 4~5
AI summary
A thread-cutting assembly for a lace-hole sewing machine has at least two pairs, each consisting of a lower-side material clamping body (11a, 11b) and an upper-side material clamp (9a, 9b), designed to clamp the material between the material clamping body (11a, 11b) and the material clamp (9a, 9b). The material clamp (9a, 9b) is designed to be displaceable relative to its corresponding material clamping body (11a, 11b). Each material clamping body (11a, 11b) has a stitch area recess (31a, 31b) in a lace-hole stitch area (30) such that a lace-hole stitch opening is created in which sewing tools can interact to sew a lace-hole seam. The assembly also has a thread cutting blade (33) and a thread counter blade (34), which is driven to be displaceable relative to the thread cutting blade (33) and works together with it to cut at least one sewing thread.The thread cutting blade (33) and the thread counter blade (34) are designed to interact at least in the lacing-hole stitching area (30). This results in an assembly that increases the reliability of thread cutting and reduces the likelihood of having to manually trim protruding thread ends after lacing.