Transfer Needle with Tapered Spring Tip and Longitudinal Slot
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Solution Overview
Problem
Existing transfer needles with hanging springs experience increased friction and potential stitch catching due to outwardly bent spring tips and manufacturing tolerances, leading to clamping effects and wear when retracted into needle channels.
Innovation Solution
The transfer needle features laterally bent transfer springs with tapered front ends guided in a longitudinal slot of the needle body, preventing outward spreading and direct contact with the channel walls, allowing smooth retraction without clamping and reducing frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the needle is pulled back into the needle channel, then the transfer needle can be retracted, but the outwardly bent spring tips cause increased friction and clamping effects
Solution Approach 1:
The longitudinal slot acts as an intermediary structure that guides the spring tips during retraction. The slot walls prevent the spring tips from contacting the needle channel walls directly, thereby mediating the interaction between the spring tips and the channel to eliminate friction and clamping effects.
Solution Approach 2:
The spring tips are given a different local quality through tapering (reduced thickness) compared to the rest of the spring body. This localized modification allows the tips to slide smoothly within the longitudinal slot without causing friction or catching stitches, while the rest of the spring maintains its structural integrity.
2Ease of manufacture
If the transfer springs protrude beyond the needle thickness, then they can function properly, but half stitches can get caught on the tips
Solution Approach 1:
The spring tips are modified with a different local quality through tapering, reducing their thickness to 50% or less of the spring width. This localized change allows the tips to pass through the longitudinal slot smoothly without catching stitches, while the broader spring body maintains sufficient protrusion for proper functionality.
Solution Approach 2:
The longitudinal slot serves as an intermediary guide that constrains the spring tips to a specific path. This prevents the tips from protruding beyond the needle boundaries in a way that would catch stitches, while still allowing the springs to maintain their necessary protrusion for function.
3Productivity
If the hanging springs are bent laterally outward, then they can transfer stitches effectively, but they spread outwards when compressed in the needle channel
Solution Approach 1:
The longitudinal slot acts as a guiding intermediary that constrains the spring tips to move only in the longitudinal direction. This prevents the tips from spreading outwards when the spring is compressed in the needle channel, while still allowing the lateral bending necessary for stitch transfer functionality.
Solution Approach 2:
The spring design incorporates a parameter change in the tip region through tapering, reducing the thickness to 50% or less of the spring width. This parameter modification allows the tips to slide smoothly within the longitudinal slot without spreading outwards during compression, while maintaining the lateral bending capability for stitch transfer.
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 design enables the transfer needle to be pulled back into the needle channel without excessive wear or friction, ensuring smooth stitch transfer and reduced force required for spring compression, preventing stitch catching and damage.
Implementation Method 1
The walls of the needle channel can compress the outwardly bent portions of the overhang spring. The resulting stretching of the hanging spring in the longitudinal direction causes the front ends of the hanging spring to be able to slide somewhat in the longitudinal slot.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The needle (1) has a longitudinal needle body (5) and a transfer spring (8) with an end permanently connected to the needle body and projecting laterally beyond the needle body and another end seated in a longitudinal slit of the needle body. The longitudinal slit includes an inlet that is open toward the fixed end of the transfer spring, where the needle body includes an elongated form with a hook (6) on its one end, and the longitudinal slit is open on a side facing away from the hook.