Sewing Machine Hold-Down Foot Stroke Control for Thick Fabrics
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Solution Overview
Problem
Existing sewing machines struggle to flexibly and precisely sew materials of different thicknesses and/or numbers of layers.
Innovation Solution
A sewing machine equipped with a driven stroke amplitude adjustment device and a driven stroke level adjustment device allows independent setting of stroke amplitude and stroke level, enabling precise control of the fabric-holding foot's movement, which can be synchronized or decoupled from the sewing machine's stitch-forming tools, using stepper motors and sensors for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fabric-holding foot is pressed against the fabric to hold it down, then the fabric is securely held, but the foot may collide with or obstruct the stitch plate when sewing thick or multi-layered materials
Solution Approach 1:
The patent applies the dynamics principle by making the fabric-holding foot movable rather than fixed. The foot can dynamically adjust its position between pressed (for secure holding) and lifted (to avoid collision) states, allowing it to adapt to different material thicknesses and layer configurations during the sewing process
Solution Approach 2:
The patent implements parameter changes by varying the vertical position parameter of the fabric-holding foot. The foot's position is adjusted based on material characteristics - pressed down for thin/single-layer materials to ensure stability, and lifted for thick/multi-layered materials to prevent obstruction with the stitch plate
2Adaptability or versatility
If the stroke amplitude and stroke level are independently adjustable, then the sewing machine can handle various material thicknesses and layers, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the single fabric-holding foot into multiple independent feet (first fabric-holding foot and second fabric-holding foot). Each foot can be independently controlled with its own stroke amplitude and stroke level adjustments, allowing versatile handling of different material configurations while keeping each individual foot's mechanism relatively simple
Solution Approach 2:
The patent implements universality by designing the adjustment devices to provide both stroke amplitude and stroke level control through integrated mechanisms. The cam-based adjustment systems serve multiple functions - controlling both the amplitude and level parameters - thereby reducing overall device complexity while achieving high adaptability
Data Source
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AI summary
A sewing machine has a stitch plate (3a) and a fabric hold-down foot (13) for performing a lifting movement to hold the fabric on the stitch plate (3a) during a sewing operation. A driven stroke amplitude adjustment device (17) is used to set the stroke amplitude of the fabric hold-down foot's movement between a top dead center and a bottom dead center. A driven stroke level adjustment device is used to set the stroke level of the fabric hold-down foot's movement (13) relative to the stitch plate (3a). A control/regulating device (11) communicates with the stroke amplitude adjustment device (17) and the stroke level adjustment device. Furthermore, operating procedures possible with the sewing machine are described. The result is a sewing machine with which fabrics of varying thicknesses and/or different numbers of layers can be sewn precisely and flexibly.