Spool Rest Thread Path Inversion for Sewing Machine Stability

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Solution Overview

Problem

Existing thread spool rest designs for sewing machines often result in unwinding of thick and durable sewing threads due to their weight, leading to entanglement and thread breakage, especially when the thread falls below the thread standing base, and are susceptible to tension changes from air currents.

Innovation Solution

A spool rest with a polygonal plate design featuring a through-hole and a thread passing groove that expands from the center to the outer edge, allowing the thread spool to be securely attached and detachable, forming a thread path that reduces unwinding and entanglement by pulling the thread to the center side of the spool, eliminating the need for an upper thread guide.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the sewing thread is fed out above the thread spool using a conventional spool rest, then the thread can be guided to the thread guide, but the sewing thread is likely to be unwound from the thread spool due to its own weight, especially when the thread is thick and durable

Engineering Contradiction:

Improvethread feedingVSAvoidthread unwinding prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent inverts the conventional thread feeding path by guiding the thread from below the spool rest upward through the cylinder portion, rather than from above downward. This reversal allows the thread to be pulled toward the center of the spool, preventing unwinding even when the thread is thick and heavy

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The spool rest with its thread guiding groove acts as an intermediary device that redirects the thread path. The groove guides the thread from below the rest, through the cylinder portion, to the front surface, creating a controlled path that prevents unwinding while maintaining ease of feeding

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the sewing thread unwound from the thread spool falls below the thread standing base, then the thread may be guided to the thread guide, but the sewing thread is entangled in the thread standing base or support stand, making feeding impossible and causing thread breakage

Engineering Contradiction:

Improvethread guidanceVSAvoidthread entanglement prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The spool rest is positioned and configured in advance to guide the thread from below the base upward through the cylinder portion before the thread can fall and become entangled. This preliminary guidance action prevents entanglement with the support stand and base structure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spool rest serves as an intermediary structure that intercepts and redirects the thread path, preventing the thread from falling below the base where entanglement would occur. The thread guiding groove on the rest provides a controlled path that avoids contact with the support stand

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a conventional spool rest structure is used, then the thread can be supported, but the thread tension changes due to air currents from air conditioners, affecting sewing conditions

Engineering Contradiction:

Improvethread supportVSAvoidthread tension stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

By inverting the thread path to run from below the spool rest upward through the cylinder portion, the thread is positioned in a more stable location less susceptible to air currents. The thread path through the center of the spool provides better tension control and stability

Inventive Principle:

Principle #13The other way round (Inversion)

4Productivity

If the sewing thread is wound around the thread spool and fed out toward the upper thread guide, then the thread can be supplied to the sewing machine, but soft threads are entangled with adjacent threads and tension changes occur

Engineering Contradiction:

Improvethread supplyVSAvoidthread entanglement and tension control

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The spool rest with its thread guiding groove acts as an intermediary that provides a controlled path for the thread from below the rest, through the cylinder portion, to the front surface. This controlled path prevents soft threads from becoming entangled with adjacent threads while maintaining stable tension

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The thread guiding groove on the spool rest provides a localized controlled environment for the thread path, ensuring that threads are guided smoothly through the cylinder portion without contact with adjacent threads, maintaining consistent tension for soft threads

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10822730B2Spool rest and thread standing device

Publication Date: 2020.11.03 JUKI CORP

AI summary

A spool rest is provided in a thread standing device of a sewing machine so as to hold a thread spool to be attachable and detachable by inserting a support installed to protrude from a thread standing base, in a cylinder portion formed at a center of the thread spool around which a sewing thread to be fed to the sewing machine is wound, the spool rest is a polygonal plate installed on the thread standing base and includes a through-hole that the support provided at a center portion of a placement surface for placing the thread spool penetrates, and a thread passing groove is formed from the center portion of the placement surface toward an outer edge portion.