Sewing Machine Feed Dog Vertical Positioning Mechanism
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Solution Overview
Problem
Existing sewing machines face issues where feed dogs may interfere with cloth feeding due to improper positioning during retraction, leading to potential cloth feeding inefficiencies and interference with the sewing operation.
Innovation Solution
A sewing machine design incorporating a vertical position changing mechanism that adjusts the turn-back points of feed dogs to be below the throat plate's surface, utilizing an eccentric rotating shaft, guide groove, and linkages to ensure reliable retraction and minimize interference during sewing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positions of the turn-back points are set below the upper surface of the throat plate with a relatively large distance, then the feed dogs can be reliably retracted below the throat plate, but the amount of protrusion of the feed dogs from the upper surface of the throat plate becomes small, leading to insufficient cloth feeding
Solution Approach 1:
The guide groove is designed to tilt relative to the horizontal direction, transforming the horizontal reciprocating motion into an elliptical trajectory. This dynamic adjustment allows the feed dogs to achieve both sufficient protrusion distance for effective cloth feeding and adequate retraction distance below the throat plate surface, resolving the contradiction between feeding efficiency and retraction reliability.
2Length of moving object
If the feed dogs are positioned above the upper surface of the throat plate during retraction, then the protrusion amount is sufficient for cloth feeding, but the retracting feed dogs may interfere with the forward feed of the cloth
Solution Approach 1:
By tilting the guide groove, the feed dogs follow an elliptical trajectory that ensures they complete their forward stroke with sufficient protrusion above the throat plate for effective cloth feeding, then retract completely below the throat plate surface before the next forward stroke begins, eliminating interference with cloth feeding.
Solution Approach 2:
The elliptical trajectory caused by the tilted guide groove ensures that the feed dogs begin retracting below the throat plate surface before the forward stroke begins, preparing the path for smooth cloth feeding without interference from protruding feed dogs.
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
This configuration ensures that feed dogs are reliably positioned below the throat plate during retraction, preventing interference and ensuring smooth cloth feeding and preparation for sewing operations, even with dimensional errors or setting errors.
Implementation Method 1
a vertical drive unit that converts a rotation of the drive shaft into a reciprocating motion in a vertical direction and transmits the reciprocating motion in the vertical direction to the feed dogs
Implementation Method 2
a guide member equipped with a guide groove that guides the square piece, and is configured to interlock the rotation of the guide member with a presser operation lever
Data Source
AI summary
Provided is a sewing machine capable of positioning feed dogs with a sufficient distance below the upper surface of a throat plate when the feed dogs are retracted. Feed dogs 3 protrude and retract from a throat plate 1. A horizontal feed drive unit 8 converts the rotation of a drive shaft 7 into a reciprocating motion in the horizontal direction and transmits the horizontal reciprocating motion to the feed dogs 3. A vertical drive unit 9 converts the rotation of the drive shaft 7 into a reciprocating motion in the vertical direction and transmits the vertical reciprocating motion to the feed dogs 3. A vertical position changing part moves turn-back points P at both ends of a forward path and a return path when the feed dogs 3 reciprocate in the horizontal direction below the throat plate 1.