Sewing Machine Thread Cutting Knife Spacer Wall
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Solution Overview
Problem
Existing thread cutting devices for sewing machines face issues with stability and operational reliability, particularly due to premature contact between the thread cutting knife and counter-knife, leading to inefficient cutting processes.
Innovation Solution
A thread cutting device with a spacer wall section, formed by a hollow grind in the thread cutting knife, ensures smooth movement of the thread cutting blade and prevents premature contact with the counter-knife, allowing for precise adjustment of the cutting force through a displaceable counter-knife and locking screw mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thread cutting knife is designed without a spacer wall section, then the structure is simpler, but premature contact with the counter-knife occurs leading to reduced stability and operational reliability
Solution Approach 1:
The thread cutting knife is segmented into functional zones: a spacer wall section (formed by hollow grinding) that maintains clearance, and a cutting edge section that contacts the counter-knife. This segmentation prevents premature contact while maintaining structural integrity.
Solution Approach 2:
The spacer wall section extends the knife structure in a dimension perpendicular to the cutting motion, creating spatial separation from the counter-knife. This dimensional addition prevents premature contact without interfering with the cutting action.
2Productivity
If the thread cutting knife contacts the counter-knife prematurely, then the cutting process starts earlier, but the cutting efficiency is reduced due to unwanted contact
Solution Approach 1:
The harmful premature contact is extracted from the cutting process by introducing the spacer wall section. This removes the unwanted interaction between the knife and counter-knife before the actual cutting moment, allowing efficient cutting to proceed without interruption.
3Ease of operation
If the counter-knife is fixed and requires realignment, then the structure is simpler, but the ease of operation is reduced due to manual realignment requirements
Solution Approach 1:
The counter-knife is merged with the gripper block assembly, allowing it to be automatically repositioned when the gripper block is adjusted. This combining of functions eliminates the need for separate manual realignment operations.
Solution Approach 2:
The counter-knife automatically adjusts its position relative to the thread cutting knife when the gripper block is repositioned. This self-adjusting mechanism eliminates the need for manual intervention to maintain proper alignment.
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The device has a counter blade (115) fixed to a base plate. A cutting edge (116) of a movable thread cutting blade is limited by a cutting-wall section (119) of an upper thread drawing blade wall (119a) of the cutting blade. The wall passes into a distance-wall section (121) beyond the cutting edge, so that the cutting blade adjacent to the cutting edge comes in contact with the counter blade during thread cutting. The distance-wall section is arranged at a distance from a movement plane (120) of the cutting blade. The cutting blade is designed as a thread draw knife (37).