Compound Needle Two-Stage Blade Positioning
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Solution Overview
Problem
The existing compound needles for flatbed knitting machines have blades that are undesirably long in the front-rear direction, making accurate coupling and positioning of the opening/closing body and base body challenging, and there is a risk of decoupling due to bending moments when the blades are moved relative to the needle body.
Innovation Solution
A compound needle design with an opening/closing body having a rear portion formed into two stages, where the upper stage extends over the lower stage, and the base body has a coupling groove on its side surface, allowing easy positioning and reducing the force applied to the coupling portion, with the upper stage providing sliding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blades are made long in the front-rear direction to ensure proper opening and closing function, then the opening/closing function is improved, but the coupling precision deteriorates and the risk of decoupling increases
Solution Approach 1:
The blade is divided into two distinct stages: a lower stage that extends rearward and an upper stage that extends forward. This segmentation allows the lower stage to provide coupling engagement with the base body while the upper stage provides the necessary opening/closing function, resolving the contradiction between operational effectiveness and coupling precision.
Solution Approach 2:
The blade transitions from a single-dimensional linear structure to a two-dimensional configuration with vertical stacking. The lower stage and upper stage are positioned at different vertical levels, allowing independent functional optimization: the lower stage engages with the base body in the horizontal plane while the upper stage performs the opening/closing action, thereby improving both coupling precision and operational function.
2Ease of operation
If the blades are made long to ensure proper opening and closing, then the opening/closing function is improved, but the structural strength deteriorates due to increased bending moments
Solution Approach 1:
By segmenting the blade into lower and upper stages, the structural load is distributed across two separate structural elements rather than one long continuous blade. The lower stage provides structural support and coupling engagement, while the upper stage provides the opening/closing function, reducing the bending moment on any single component.
Solution Approach 2:
The upper stage is positioned above and partially overhangs the lower stage, creating a nested configuration. This nesting arrangement allows the lower stage to bear the primary structural load and coupling forces, while the upper stage provides the necessary functional overhang for opening/closing, thereby improving overall structural strength while maintaining operational function.
3Ease of operation
If additional components are added to provide sliding resistance, then the sliding resistance function is improved, but the device complexity increases
Solution Approach 1:
The lower stage of the blade serves multiple functions simultaneously: it provides coupling engagement with the base body, supports the upper stage structurally, and generates sliding resistance through its interaction with the needle groove. This multi-functionality eliminates the need for separate dedicated sliding resistance components, thereby improving operational performance while maintaining structural simplicity.
Solution Approach 2:
The coupling function and sliding resistance function are merged into a single integrated structure - the lower stage of the blade. The lower stage's engagement with the base body and interaction with the needle groove simultaneously provides coupling precision and sliding resistance, eliminating the need for separate components and reducing overall device complexity.
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 facilitates easy and accurate coupling of the opening/closing body and base body, reduces the risk of decoupling, and simplifies the structure by eliminating the need for additional sliding resistance components, while maintaining strength and accuracy.
Implementation Method 1
the upper stage having a resistance portion which makes slide contact with a side wall of the needle groove and generates sliding resistance
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
[Problem to be solved] The present invention provides a compound needle for a flatbed knitting machine in which positioning of an opening/closing body and a base body is easily made when the opening/closing body and the base body are coupled to each other and a large force is hardly applied to the coupling portion. [Solution] A coupling portion 16 between blades 13, 14 as an opening/closing body 12 of a slider 11 and a base body 15 is positioned in the front-rear direction by providing a coupling groove 15b formed so as to correspond to the lengths of upper stages 13e, 14e on one side face of the base body 15, fitting the upper stages 13e, 14e into the coupling groove 15b, and making rear ends of the connecting portions 13d, 14d have in contact with an contacting portion 15c. Rear portions of the blades 13, 14 are divided into the upper stages 13e, 14e and lower stages 13c, 14c so that the lengths of the blades 13, 14 can be shortened in the front-rear direction. A force required for positioning the coupling portion 16 in the vertical direction can be made to act from the lower side easily. The lower stages 13c, 14c sag and absorb a force received by front portions of the blades 13, 14 from the bottom of the slider groove 17d so that the force is hardly applied to the coupling portion 16.