Sewing Machine Wiper Device Thread Retention
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Solution Overview
Problem
Conventional wiper devices for sewing machines either fail to reliably retain the needle thread-end after cutting, leading to deformation of initial stitches, or increase the complexity and cost due to synchronized drive mechanisms with thread cutting devices.
Innovation Solution
A wiper device with a wiper member that cooperates with the embroidery presser foot's cloth presser to clamp and retain the needle thread-end, using a frictional-resistance applying member to prevent the thread-end from falling, thus ensuring reliable retention without complex mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wiper device merely pulls out the needle thread-end above the workpiece cloth without retention mechanism, then the device structure remains simple, but the needle thread-end is prone to twist and deformation of initial stitches occurs
Solution Approach 1:
The patent merges the thread retention function with the existing presser foot structure by providing a through-hole in the presser foot that allows the wiper member to pass through and retain the thread-end. This integration eliminates the need for separate retention mechanisms while ensuring reliable thread-end holding.
Solution Approach 2:
The presser foot is given multiple functions: it not only presses the workpiece cloth during sewing but also serves as a retention structure for the needle thread-end through its through-hole design. This multi-functionality reduces overall device complexity while improving thread retention reliability.
2Reliability
If a wiper drive mechanism is synchronized with the thread cutting movement of a moving blade, then the needle thread can be reliably wiped, but the device complexity, size and cost increase
Solution Approach 1:
The wiper member is positioned and activated before the thread cutting action occurs. The wiper member is swung to wipe the thread-end in advance, and then the thread cutting unit cuts the thread. This preliminary action ensures the thread is properly positioned and wiped before cutting, eliminating the need for complex synchronized drive mechanisms.
Solution Approach 2:
The patent separates the wiper drive mechanism from the thread cutting mechanism, allowing independent operation of each component. The wiper member is driven by a separate mechanism that activates it before thread cutting, rather than synchronizing with the moving blade's motion, thereby reducing overall device complexity.
3Productivity
If the wiper member is positioned close to the needle thread, then the wiping action is effective, but the wiper member may interfere with the needle bar movement
Solution Approach 1:
The wiper member is designed to swing dynamically between a retracted position (during needle bar movement) and an extended wiping position (during thread wiping operation). This dynamic positioning allows the wiper member to be close to the needle thread for effective wiping without interfering with needle bar movement, as it retracts when needed.
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
The solution ensures proper formation of initial stitches in subsequent sewing sequences, reduces device size and manufacturing costs, and prevents thread-end loss during the wiping operation.
Implementation Method 1
using a frictional-resistance applying member to prevent the thread-end from falling
Data Source
AI summary
The wiper device for a sewing machine having a wiper member swingable from the operating position to a non-operating position on an embroidery presser foot, in which a needle thread-end is retained by being clamped between a frictional-resistance applying member fixed to an underside of a thread engagement portion located on a distal end of the wiper member and an upper surface of a cloth presser pressing a workpiece cloth by a returning movement of the wiper member from an operating position in which the wiper member performs a thread wiping operation to a stand-by position.