External Sewing Unit With Needle-Holder Synchronization Control
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Solution Overview
Problem
Existing sewing machines face challenges in improving the quality of seams, particularly when forming buttonholes, due to inefficiencies in controlling the movement of the sewing needle and fabric holder, leading to potential interference and inconsistent stitching.
Innovation Solution
A sewing machine external unit with a holder, driver, pressing member, position detector, signal output part, and controller that work together to synchronize the movement of the sewing needle and fabric holder based on detected positions, adjusting speed and timing to prevent interference and ensure precise stitching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the sewing needle and fabric holder move independently without synchronization control, then the device complexity is reduced, but the manufacturing precision of seams deteriorates due to potential interference and inconsistent stitching
Solution Approach 1:
The patent implements a feedback control system where a position detector continuously monitors the position of the pressing member and sends signals to the controller. The controller adjusts the movement of the fabric holder based on this feedback to maintain proper synchronization with the sewing needle, ensuring consistent seam quality without requiring overly complex mechanical linkages.
Solution Approach 2:
The patent replaces complex mechanical synchronization mechanisms with an electronic control system. Instead of using mechanical linkages to physically connect the needle and holder movements, the system uses a controller with signal processing to coordinate movements electronically, reducing mechanical complexity while maintaining precision.
2Reliability
If the pressing member remains pressed against the fabric throughout the sewing cycle, then the fabric is well-supported, but the sewing needle cannot complete its up-down motion due to interference
Solution Approach 1:
The pressing member is designed with dynamic movement capability, transitioning between pressed and raised states based on the sewing needle's position. The controller raises the pressing member when the needle is in the up position and presses it down when the needle is in the down position, allowing the system to adapt its support level dynamically rather than maintaining a fixed state.
Solution Approach 2:
The pressing member operates in periodic cycles synchronized with the needle's reciprocating motion. It alternates between pressing the fabric during needle insertion and raising during needle retraction, creating a rhythmic pattern of support that ensures both fabric stability and needle freedom of motion.
3Productivity
If the fabric holder moves at high speed to increase productivity, then the sewing output increases, but the synchronization with the sewing needle becomes inconsistent leading to poor seam quality
Solution Approach 1:
The position detector provides real-time feedback on the pressing member's position, allowing the controller to adjust the fabric holder's movement speed dynamically. This feedback mechanism ensures that even at high productivity speeds, the synchronization between needle and holder remains precise, maintaining stitch consistency.
Solution Approach 2:
The system dynamically changes the movement parameters of the fabric holder based on the sewing phase. The controller adjusts position, speed, and acceleration parameters in real-time to match the needle's motion characteristics, enabling high-speed operation while maintaining synchronization precision through continuous parameter optimization.
Data Source
AI summary
A sewing machine external unit includes: a holder holding fabric; a driver being detachable from a bed of a sewing machine and driving the holder along an upper surface of the bed; a pressing member moving in an up-down direction according to movement of a sewing needle in the up-down direction, pressing the fabric while the sewing needle is stuck in the fabric, and rising together with the sewing needle in response to the sewing needle coming out of the fabric and rising; a position detector detecting a position of the pressing member in the up-down direction; a signal output part outputting a signal to the sewing machine; and a controller outputting a needle drive signal for driving the sewing needle from the signal output part to the sewing machine, and controlling driving of the holder and/or the sewing needle based on a detection result of the position detector.