Overlock Sewing Machine Single Shaft Drive Mechanism
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Solution Overview
Problem
Conventional overlock sewing machines have complex and costly drive mechanisms for the overlooper and underlooper, requiring numerous parts and laborious installation and timing adjustments, with thread engagement processes being cumbersome and time-consuming.
Innovation Solution
A simplified drive mechanism using a single looper drive shaft with swing generating members for both the overlooper and underlooper, eliminating the need for separate drive shafts and eccentric cams, and a switch mechanism to facilitate external thread engagement and automatic return to the sewing position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate eccentric cams and drive shafts are used for the overlooper and underlooper, then the driving function is reliable, but the device complexity and number of parts increase
Solution Approach 1:
The patent combines two separate drive shafts into a single integrated drive shaft that drives both the overlooper and underlooper. The drive shaft includes a first eccentric cam for the overlooper and a second eccentric cam for the underlooper, both integrated on the same shaft. This merging reduces the number of parts while maintaining the reliable driving function through the preserved eccentric cam mechanism.
Solution Approach 2:
The single drive shaft performs multiple functions by integrating both eccentric cams on it. It simultaneously drives the overlooper via the first eccentric cam and the underlooper via the second eccentric cam, making the drive shaft a multi-functional component that replaces what previously required two separate shafts.
2Reliability
If separate eccentric cams and drive shafts are used for the overlooper and underlooper, then the driving function is reliable, but the installation and timing adjustment become laborious
Solution Approach 1:
By merging the two drive shafts into one integrated shaft with both eccentric cams, the patent reduces the number of installation steps. Instead of installing and timing-adjusting two separate shafts, the user installs a single shaft that comes pre-configured with both cams, significantly simplifying the installation process while maintaining driving reliability.
3Ease of operation
If a threading base, guide rail, and slider are provided for thread engagement, then thread engagement is possible, but the number of parts and cost increase
Solution Approach 1:
The patent removes the threading base, guide rail, and slider components from the thread engagement mechanism. Instead of using these separate parts, the underlooper itself is made movable along the looper arm, extracting the complex guiding mechanism and replacing it with a simpler direct movement approach that reduces part count while maintaining thread engagement functionality.
Solution Approach 2:
The looper arm is given a dual function: it serves as both the structural support for the underlooper and as the guide path for the underlooper's movement during thread engagement. This eliminates the need for separate guide rails and threading bases, as the looper arm itself provides the necessary guidance.
4Ease of operation
If the underlooper is moved to the right most position for thread engagement, then external threading is enabled, but the operation time increases
Solution Approach 1:
The patent makes the underlooper dynamically movable along the looper arm rather than fixed in position. The underlooper can be quickly slid along the looper arm to the rightmost position for external threading and then returned to the working position, enabling fast dynamic adjustment that reduces the time penalty compared to fixed-position systems.
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 configuration reduces the number of parts, simplifies installation, and streamlines thread engagement, allowing for easier assembly and operation while ensuring uninterrupted sewing.
Implementation Method 1
a swing generating member which is fixed to the looper drive shaft and has a first swing generating portion for swinging the overlooper, and a second swing generating portion for swinging the underlooper
Data Source
AI summary
An overlock sewing machine including a main shaft rotated by a sewing machine motor; a vertically moving sewing needle and an overlooper and an underlooper respectively driven by the rotation of the main shaft; a single looper drive shaft forming overlock stitches in cooperation with the overlooper, the underlooper and the sewing needle and rotated by the rotation of the main shaft, shaft line thereof being arranged perpendicularly to the main shaft; and a swing generating member having first and second swing generating portions fixed to the looper drive shaft for swinging the overlooper and the underlooper respectively; a first and second swing link mechanisms, both of which extend perpendicularly to the looper drive shaft, swinging the overlooper and the underlooper by conveying the drive force generated by the first and second sewing generating portions.