Sewing Machine Feed Dog Actuation for Variable Stitch Control
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Solution Overview
Problem
Existing sewing machines lack the flexibility to adapt to varying sewing conditions, such as fabric composition and seam direction, which limits their ability to produce consistent stitch lengths and optical quality.
Innovation Solution
The sewing machine incorporates adjustable feed mechanisms, including upper and lower feed dogs with actuation drives controlled by a signal-connected control device, allowing for precise adjustment of feed lengths and ratios, enabling flexible material feed and automatic thread tension adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed feed mechanisms are used in conventional sewing machines, then the structure is simple and reliable, but the flexibility to adapt to varying sewing conditions (fabric composition, seam direction) is limited
Solution Approach 1:
The patent applies dynamics by making the feed mechanisms adjustable during operation. The upper and lower feed dogs are equipped with adjustment drives that can change feed lengths dynamically based on sewing conditions. This allows the system to transition from a static to a dynamic state, enabling adaptation to different fabric compositions and seam directions while maintaining mechanical robustness through structured adjustment devices.
Solution Approach 2:
The patent implements parameter changes by allowing the feed lengths of the upper and lower feed dogs to be varied during operation. The adjustment drives modify the feed parameters (feed length, feed ratio) based on detected sewing conditions such as fabric composition and seam direction. This enables the system to optimize stitching parameters in real-time without requiring complete redesign for different sewing tasks.
2Manufacturing precision
If manual adjustment of feed lengths is used, then the device complexity is low, but the consistency of stitch lengths and optical quality cannot be maintained under varying sewing conditions
Solution Approach 1:
The patent applies feedback by using detection devices that monitor sewing conditions (fabric composition, seam direction) and feed this information to the control device. The control device then automatically adjusts the feed lengths of the upper and lower feed dogs to maintain consistent stitch lengths. This closed-loop feedback system ensures manufacturing precision by continuously optimizing feed parameters based on actual sewing conditions rather than relying on manual preset adjustments.
Solution Approach 2:
The patent implements self-service by enabling the sewing machine to automatically adjust its own feed parameters without external intervention. The control device receives input from detection devices and autonomously commands the adjustment drives to modify feed lengths, allowing the system to self-optimize for consistent stitch quality under varying conditions.
3Adaptability or versatility
If multiple separate adjustment mechanisms are used for upper and lower feed dogs, then individual feed lengths can be adjusted independently, but the device complexity and space requirements increase
Solution Approach 1:
The patent applies merging by integrating the adjustment drives for the upper and lower feed dogs into a coordinated system. Rather than using completely separate adjustment mechanisms, the system combines the adjustment functions through a unified control architecture that manages both feed dogs. This reduces the overall space required while maintaining the ability to adjust feed lengths independently through shared control resources and compact mechanical integration.
Solution Approach 2:
The patent implements universality by designing adjustment devices that can serve multiple functions. The adjustment drives are capable of controlling both the upper and lower feed dogs, and the control device can manage various adjustment modes (individual feed length adjustment, feed ratio adjustment) using the same hardware resources. This multi-functionality reduces the need for dedicated mechanisms for each adjustment task, thereby saving space.
Data Source
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AI summary
A sewing machine has a transport device (14) for the intermittent feeding of the fabric. The transport device (14) has at least one upper feed dog (15) and at least one lower feed dog (16, 17) for intermittent frictional contact with the top and bottom surfaces of the fabric, respectively. Mechanical upper and lower feed adjustment devices are used to adjust the feed length of the feed dogs (15 to 17). These adjustment devices are moved by actuators. A control unit communicates with the lower feed actuator and the upper feed actuator and has a memory unit. This memory unit stores data relating to the sewing sequences to be executed, as well as setting data for the independent control of the actuators during the execution of the sewing sequence.The result is a sewing machine in which the flexibility of the fabric feed is increased to adapt to different sewing requirements.