Overlock Sewing Machine Upper Knife Mechanism
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Solution Overview
Problem
Conventional overlock sewing machines with upper knives have a complex configuration that increases the number of components and installation space, leading to a heavy load on the sewing machine main shaft, which can affect durability.
Innovation Solution
The overlock sewing machine incorporates a simplified mechanism with an upper knife driving unit, interlocking switching unit, and position switching unit, utilizing a rotatable shaft, links, and a biasing unit to reliably withdraw the upper knife to the lower side of the throat plate, reducing interlocking members and minimizing the load on the main shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional link members and delinking mechanisms are used to withdraw the upper knife, then the upper knife can be reliably withdrawn to the lower side of the throat plate, but the number of components and installation space increase
Solution Approach 1:
The patent extracts and eliminates unnecessary link members (first parallel link, second parallel link, knife oscillating arm, upper knife link) from the conventional mechanism. By directly coupling the rod to the upper knife holder and removing the complex delinking mechanism, the invention achieves upper knife withdrawal reliability while significantly reducing the number of components and installation space requirements.
2Reliability
If multiple link members and delinking mechanisms are provided for upper knife withdrawal, then the upper knife can be positioned at the lower side of the throat plate, but the load on the sewing machine main shaft increases
Solution Approach 1:
The patent removes the useless operative links (first parallel link, second parallel link, knife oscillating arm, upper knife link) that created heavy loading on the main shaft. The simplified rod-directly-coupled-upper-knife-holder mechanism eliminates these unnecessary power transmission paths, reducing the load on the main shaft while maintaining reliable upper knife positioning at the lower side of the throat plate.
Solution Approach 2:
The patent segments the upper knife mechanism into independent functional units: the rod for power transmission, the upper knife holder for positioning, and the biasing means for withdrawal control. This segmentation allows each component to perform its function efficiently without requiring multiple interconnected link members that would increase the overall load on the main shaft.
3Ease of operation
If conventional link members are used for power transmission and upper knife withdrawal, then the upper knife can be controlled, but the installation space increases
Solution Approach 1:
The patent extracts and removes the space-consuming link members (first parallel link, second parallel link, knife oscillating arm, upper knife link) from the conventional arrangement. The simplified mechanism using only a rod and direct coupling to the upper knife holder achieves the same upper knife control functionality with significantly reduced installation space requirements.
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 components and installation space, enhances durability by minimizing unnecessary links, and ensures reliable power transmission to the upper knife, while allowing for efficient switching between interlocking and release states.
Implementation Method 1
The rod is provided with an eccentric cam rotating along with a sewing machine main shaft at one end portion
Implementation Method 2
The cam portion rotates along with the shaft body, and engages with the upper knife position switching unit, to put the upper knife position switching unit into motion
Implementation Method 3
a biasing unit is provided for the rod to provide biasing force in a direction in which the notch and the engaging portion firmly adhere to one another
Data Source
AI summary
An overlock sewing machine includes an upper knife which is movable to a withdrawn position or a driving position, an upper knife driving unit which moves the upper knife, an interlocking switching unit which switches between an interlocking state in which the upper knife driving unit and the upper knife are interlock and a release state in which the upper knife driving unit and the upper knife are released, an upper knife position switching unit which switches the upper knife to the driving position or the withdrawn position, and an operating unit which drives the interlocking switching unit and the upper knife position switching unit such that the interlocking switching unit is brought into the interlocking state when the upper knife is switched to the driving position, and the interlocking switching unit is brought into the release state when the upper knife is switched to the withdrawn position.