Single-bed Circular Knitting Machines
Besides the needles, during the stitch formation cycle special components called "sinkers" also operate that are positioned perpendicularly to the needles. Sinkers play two fundamental roles: they hold the already formed fabric down when the needles rise to knit the new course and support the fabric when the previous course is knocked over.
The sinker, which has a particular shape, has two main parts: the nose (upper section) and the breast (lower section) which can move forward and backward horizontally driven by special cams.
Stitch Formation Cycle on Single-bed Knitting Machines
As shown in picture 107, the course in its starting position (Step A) lies on the breast of the sinker; when the sinker moves forward (Step B), according to the stitch formation movement, the fabric reaches the zone under the sinker nose called "throat"; when the needle rises, the previous stitches, retained by the sinkers, open the needle latches (Step C).
When the needle, after having reached its highest position (Step C) starts lowering, a new thread is fed (Step D): during this step, the sinkers retain the previous stitches in the sinker throat.
The needles continue their downstroke (Step E), the sinkers draw back and the previous stitches close the latch so that the new thread is retained inside the needle hook.
Finally (Step F) the needles reach their lowest position, the previous stitches slip over the closed hook and knock over at the bottom of the new stitch.
Picture 106 - A sinker
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