Needle-threading device for multi-needle sewing machines
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Solution Overview
Problem
Existing needle-threading devices for sewing machines with multiple needles are limited in their ability to accurately thread needles at different heights, leading to complexity and size issues.
Innovation Solution
A needle-threading device with a vertically movable and rotatable needle-threading shaft, a control lever for lowering and rotating the shaft, and an interlocking mechanism that allows the needle-threading hook to move arbitrarily in the left-right and up-down directions to accommodate different needle heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the positioning member has a multi-stepped shape to define multiple relative positions for threading multiple needles, then the ability to thread multiple needles at different heights is improved, but the device becomes complex and large-sized
Solution Approach 1:
The needle-threading end section is made movable relative to the needle-threading shaft through a sliding mechanism. The positioning body can slide along the sliding body to adjust the horizontal position, while the sliding body itself moves vertically relative to the shaft. This dynamic adjustment system replaces the static multi-stepped structure, allowing the same component to adapt to multiple needle positions without increasing overall device complexity.
Solution Approach 2:
The needle-threading device is divided into separable components: the needle-threading shaft, the sliding body, and the positioning body with needle-threading hook. This segmentation allows independent adjustment of each component's position, enabling flexible adaptation to different needle configurations without requiring a complex integrated structure.
2Device complexity
If only a part of the needle-threading device including the needle-threading hook slides or rotates relative to the device, then the device is simplified and reduced in size, but the number of needles that can be used and the positional relationship thereof are limited
Solution Approach 1:
The positioning body can slide along the sliding body to dynamically adjust its horizontal position, allowing adaptation to different needle spacings and configurations. This sliding mechanism provides continuous positional adjustment rather than fixed positions, enhancing versatility while maintaining structural simplicity.
Solution Approach 2:
The sliding body and positioning body mechanism serves multiple functions: it positions the needle-threading hook horizontally for different needles, adjusts vertical position through its movement relative to the shaft, and can accommodate various needle arrangements. This multi-functional design replaces what would otherwise require multiple specialized components.
3Manufacturing precision
If the needle-threading hook is inserted through needle holes at varying heights in multiple needles, then threading accuracy for multiple needles is improved, but the device structure becomes more complex to accommodate the varying heights
Solution Approach 1:
The sliding body moves vertically relative to the needle-threading shaft, allowing the positioning body and needle-threading hook to achieve different vertical positions corresponding to needles at varying heights. This vertical movement capability provides precise positioning for each needle height without requiring complex mechanical structures, as the movement is achieved through the simplified sliding mechanism guided by the slot cam.
Data Source
AI summary
The needle-threading device includes a needle-threading shaft that is parallel to a vertically-moving needle bar and that is vertically movable and rotatable, a control lever that lowers and rotates the needle-threading shaft, a needle-threading end section provided at a lower end of the needle-threading shaft and having a needle-threading hook, and a needle-threading stopper provided at the needle bar and defining a lowered stoppage position of the needle-threading shaft. The needle-threading end section lowered by operating the control lever rotates at the lowered stoppage position and causes the needle-threading hook to be inserted through a needle hole of one needle of a plurality of needles provided at the needle bar. The needle-threading end section includes a sliding body that vertically moves relative to the needle-threading shaft, a positioning body slidable relative to the sliding body, and an interlocking mechanism that vertically moves the sliding body.