Compound Needle Slider Cam Face Design for Flatbed Knitting
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Solution Overview
Problem
In flatbed knitting machines, the slider of the compound needle tends to move backward due to increased component forces when dealing with double stitches or thick yarns, especially at higher driving speeds, which can lead to malfunction during yarn catching and loop formation.
Innovation Solution
The compound needle features a slider groove with a continuous cam face including a rising slope and a flat face, where the contacting portion on the bottom of the slider has a circular arc shape for point contact, preventing backward movement by generating forces perpendicular to the flat face, thus stabilizing the slider's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rising slope of the slider groove is used to close the hook, then the hook closing function is achieved, but the slider moves backward due to increased component forces when dealing with double stitches or thick yarns
Solution Approach 1:
The cam face is segmented into three distinct functional zones: a rising slope for initiating tongue movement, a flat face for stabilizing the slider during yarn catching, and a declining slope for completing the hook closing action. This segmentation allows each zone to perform its specific function without interfering with others, preventing backward slider movement while maintaining reliable hook closing.
Solution Approach 2:
The flat face is positioned on the cam face to act in advance during the yarn catching phase, stabilizing the slider before the hook closing operation begins. This preliminary stabilization prevents the slider from moving backward when component forces increase during subsequent thick yarn or double stitch operations.
2Productivity
If the driving speed is increased to improve productivity, then the knitting speed increases, but the slider is more likely to move backward due to increased component forces
Solution Approach 1:
The cam face design dynamically adapts to different operating conditions including varying driving speeds. The flat face provides continuous stabilization during the yarn catching phase regardless of speed, while the rising and declining slopes efficiently transfer motion during hook closing. This dynamic design maintains slider stability across a range of driving speeds, enabling high productivity without sacrificing reliability.
3Adaptability or versatility
If thick yarns or double stitches are processed, then fabric variety is improved, but the component forces increase causing the slider to move backward
Solution Approach 1:
The design converts the harmful backward force generated during thick yarn or double stitch processing into a beneficial stabilizing mechanism. The flat face on the cam face is specifically positioned to receive and neutralize these increased component forces during the yarn catching phase, transforming what would be a destabilizing force into a controlled interaction that maintains slider position stability while enabling processing of diverse fabric types.
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 ensures the slider remains stable and prevents backward movement, even under increased pulling forces, ensuring reliable loop formation and yarn catching, especially with thick yarns and higher speeds.
Implementation Method 1
a bottom face of the slider groove acting on a bottom portion of the slider has a rising slope and a flat face which are formed as a continuous cam face
Implementation Method 2
a contacting portion which has a circular arc shape and makes point contact with the flat face
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
[Abstract] [Problem to be solved] There is provided a compound needle for a flatbed knitting machine, which can make a slider hard to move backward owing to a pulling force to a downward of a needle bed gap, which acts on an old loop, even if a state where a tongue rises relatively is temporarily held, when the tongue is moved relatively so as to close a hook. [Solution] A bottom portion of a tongue 6, there formed a step portion 6e between a slide contact portion 6c and an contacting portion 6d, has a shape concaved to the upper side in comparison with a conventional shape 6f. A stitch held on an upper edge 6a receives a pulling force to a downward of a needle bed gap 8. A direction that the pulling force acts on the stitch is almost identical to a direction that the contacting portion 6d contacts a flat face 4b. Therefore, since a component force in the direction along the flat face 4b is hardly generated, a slider 5 is made hard to move backward. If the contacting portion 6d has a circular arc shape, only a component force in the direction constantly perpendicular to the flat face 4b is generated and a component force in the direction along the flat face 4b is not generated, so that the slider 5 can be made further hard to move backward.