Sewing Machine Feed Dog Plateau Transport Path
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Solution Overview
Problem
Sewing machines face challenges in reliably transporting sewing material under unfavorable conditions, such as with very soft, hard, or thick materials, as existing feed mechanisms struggle to maintain consistent transport forces and reproducibility.
Innovation Solution
The sewing machine employs a feed dog drive with a movement curve that maintains a consistent distance from the throat plate, using eccentrics to derive the feed dog movement curve from the drive shaft rotation, ensuring constant transport forces by minimizing distance deviations, particularly with triangular eccentrics that allow for fine-tuned movement profiles and adjustment gears for stitch length regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feed mechanisms are used, then the sewing machine can operate with standard materials, but transport reliability deteriorates with very soft, hard, or thick materials
Solution Approach 1:
The patent applies dynamics by implementing a feed dog movement curve with a plateau transport path that maintains constant distance from the throat plate. This dynamic movement profile allows the feed dog to adapt to different material properties (soft, hard, thick) while ensuring reliable transport. The plateau portion of the movement curve keeps the feed dog at a stable distance, providing consistent transport forces regardless of material characteristics.
Solution Approach 2:
The patent changes the movement parameters of the feed dog by defining a specific movement curve with a plateau transport path. This parameter change involves maintaining the feed dog distance from the throat plate within a narrow range (deviation not more than 15% or 10%) during the plateau phase, which constitutes at least 50% or 60% of the transport path. This parameter optimization ensures reliable transport across various material types.
2Productivity
If the feed dog distance from the throat plate varies significantly, then the transport path is shorter, but transport force consistency deteriorates
Solution Approach 1:
The patent uses a dynamic movement curve with a plateau transport path that maintains constant feed dog distance during the majority of the transport cycle. This dynamic control ensures that transport forces remain consistent while still achieving efficient material advancement. The plateau phase occupies at least 50% or 60% of the transport path, balancing efficiency and force consistency.
Solution Approach 2:
The patent optimizes movement parameters by limiting feed dog distance deviation from extreme distance to no more than 15% or 10% during the plateau transport path. This parameter control ensures consistent transport forces while maintaining productive transport speed. The plateau portion represents at least 50% or 60% of the total transport path length.
3Device complexity
If conventional eccentrics are used, then the feed dog movement is simple, but play-free operation and reliability deteriorate
Solution Approach 1:
The patent employs asymmetric triangular eccentrics instead of conventional symmetric round eccentrics. This asymmetric design allows for precise control of the feed dog movement curve, enabling the plateau transport path and consistent distance maintenance. The triangular shape provides the necessary mechanical advantage to achieve play-free operation while maintaining drive mechanism simplicity.
Solution Approach 2:
The triangular eccentric design dynamically controls the feed dog movement to follow the desired curve with plateau transport path. This dynamic mechanism ensures play-free operation by maintaining proper clearance and force transmission throughout the cycle, improving reliability without significantly increasing device complexity.
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 reliable and play-free operation, maintaining constant transport forces even with thick materials, and adapts to various material types by optimizing movement curves for speed and acceleration, ensuring efficient and precise stitching.
Implementation Method 1
at least one of the eccentrics enables the feed dog movement curve to be derived from the drive shaft rotation. Two eccentrics have proven to be particularly suitable for specifying the feed dog movement curve.
Data Source
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AI summary
A sewing machine has a needle bar for holding a sewing needle. Furthermore, the sewing machine has a stitch plate in a support plate for the fabric and at least one feed dog for transporting the fabric within a stitch area of the stitch plate. A feed dog drive is designed such that a movement curve (53; 56) of the at least one feed dog runs parallel to the stitch plate (11) along a plateau transport path (PUT; POT) between a transport start point (54) and a transport end point (55), with a distance deviation between an extreme distance (UT0; OT0) of the feed dog (13) to the stitch plate (11) of no more than 20%. The plateau transport path (PUT; POT) is at least 40% of a distance (TSE) between the transport start point (54) and the transport end point (55) along the transport direction (12).The result is a sewing machine with reliable fabric transport even under unfavorable conditions affecting the fabric, for example with very soft, very hard, and/or very thick fabric.