Textiles: knitting – Needle cooperating elements – Sinkers or web holders
Reexamination Certificate
1999-05-27
2001-01-23
Worrell, Danny (Department: 3741)
Textiles: knitting
Needle cooperating elements
Sinkers or web holders
C066S104000, C066S115000
Reexamination Certificate
active
06176107
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to circular knitting machines and their sinkers. In particular, the invention relates to controlling the vertical motion of radially reciprocating sinkers of circular knitting machines.
BACKGROUND OF THE INVENTION
Circular knitting machines are widely used to produce knitted fabric, such as knitted fabric that is tubular. A conventional circular knitting machine includes a vertically extending cylinder, and multiple sinkers and latch needles that extend around and move relative to the upper end of the cylinder. The sinkers reciprocate radially and the latch needles reciprocate vertically in a cooperative fashion to produce knitted fabric. For example, U.S. Pat. Nos. 4,459,830; 4,765,155; 5,182,927; 5,477,707; 5,577,401 and 5,609,044 disclose circular knitting machines, and each of those patents is incorporated herein by reference.
It is important to control accurately the vertical movement of the sinkers of a circular knitting machine. For example, U.S. Pat. Nos. 1,684,682; 2,120,796; 3,230,742; 3,377,823; 4,519,221; 4,665,718 and 5,564,291 discloses circular knitting machine cylinders having annular ledges that at least partially define the paths of associated sinkers. The sinkers have upper and lower arms that bear upon opposite surfaces of the ledges.
Notwithstanding past improvements to circular knitting machines, at least some modern circular knitting machines experience problems when sinkers encounter deposits of lint, dirt, or the like, on an upper surface of the circular knitting machine cylinder upon which the sinkers slide. Accumulations on the cylinder upper surface can cause the sinkers to ride upward, resulting in “sinker lines” in the knitted fabric. The presence of sinker lines is a defect that knitters wish to avoid. Efforts have been made to avoid this problem by trying to keep the upper regions of the cylinder clean by forcing air in and around the vertically and radially extending slots in which the sinkers at least partially reside. Whereas this approach works fairly well, it is not an infallible solution, and this approach requires extra parts such as fans, compressors, ducting, filters and so forth.
Downward motion of the sinkers is also undesirable because it may lead to sinker lines or problems such as smashing of sinker parts and other parts of the circular knitting machine. In machines that have been run for some time, downward motion of the sinkers can occur due to wear between the sinkers and the cylinder upper surface. Over time, this wear causes grooves to form in the upper surface of the cylinder, and the sinkers may ride downwardly into grooves. Whereas it is known in the art to harden the upper surface of the cylinder, or a portion thereof, so as to reduce the wearing and resulting grooves, such hardening can be expensive, and can in some cases cause warping and tolerance problems.
Accordingly, there is a need for an improved mechanism for restricting vertical movement of sinkers.
SUMMARY OF THE INVENTION
The present invention restricts undesirable vertical movement of sinkers, and provides other advantages, while simultaneously avoiding problems with binding or excessive friction. More specifically, at least one readily replaceable restricting member is carried by a cylindrical portion of a circular knitting machine and is operative to restrict at least upward or downward movement of the sinkers. For a circular knitting machine having a cylinder with a cylinder top ring, the cylindrical portion to which the restricting member is mounted is preferably the cylinder top ring. For a circular knitting machine in which the cylinder is not equipped with a cylinder top ring, the cylindrical portion to which the restricting member is mounted is preferably the upper portion of the cylinder.
In accordance with one aspect of the present invention, the restricting member is biasingly engaged to the cylindrical portion such that the biased restricting member extends at least partially around the cylindrical axis of the cylindrical portion. The sinkers are operative for reciprocating radially relative to the cylindrical portion and the biased restricting member such that sliding contact is defined between the sinkers and one or more bearing-like surfaces of the biased restricting member.
In accordance with one aspect of the present invention, the biased restricting member is manually bent and thereafter released so that the bias of the biased restricting member causes it to become biasingly engaged to the cylindrical portion. Most preferably, the biased restricting member is released so that the biased restricting member becomes biasingly engaged within a receiving channel that is defined by the cylindrical portion and encircles the cylindrical axis of the cylindrical portion. It is preferable for the biased restricting member to remain stationary within the receiving channel during the reciprocating of the sinkers.
In accordance with one aspect of the present invention, the cylindrical portion comprises a plurality of spaced-apart, radially extending protrusions, and a plurality of radially extending slots are defined between the protrusions. The slots are operative for at least partially receiving the reciprocating sinkers, and the protrusions at least partially define the receiving channel such that the receiving channel and the biased restricting member at least partially bisect the slots.
In accordance with some of the embodiments of the present invention, an interior surface of the cylindrical portion defines an opening to the receiving channel. In accordance with other embodiments of the present invention, an exterior surface of the cylindrical portion defines an opening to the receiving channel. Both types of openings to the receiving channel extend at least partially around the cylindrical axis of the cylindrical portion so that the biased restricting member can be readily introduced into and removed from the receiving channel, whereby the biased restricting member is readily replaceable.
In accordance with one aspect of the present invention, the biased restricting member may be biased toward a substantially straight configuration, in which case the biased restricting member has opposite ends. The opposite ends of the biased restricting member may abut in an end-to-end manner when the biased restricting member is properly positioned within the receiving channel. Alternatively, the opposite ends of the biased restricting member may not abut in an end-to-end manner when the biased restricting member is properly positioned within the receiving channel, in which case the biased restricting member can be characterized as having a discontinuous circumference.
In accordance with another aspect of the present invention, the biased restricting member defines a relaxed diameter while the biased restricting member is separate from the cylindrical portion. As one example, the biased restricting member may be in the form of a hoop. Such a hoop may be formed, for example, by joining the opposite ends of a biased restricting member, such that the opposite ends define an end-to-end arrangement. As another example, the opposite ends of a biased restricting member are not joined, but the biased restricting member at least partially defines an arcuate configuration while separate from the cylindrical portion and relaxed, and the arcuate configuration defines the relaxed diameter. When the receiving channel has an outwardly facing opening, the relaxed diameter is preferably smaller than the diameter of the receiving channel. When the receiving channel has an inwardly facing opening, the relaxed diameter is preferably larger than the diameter of the channel.
When the biased restricting member is not in the form of a hoop, or the like, it may be preferred for the length of the biased restricting member to be greater than the circumference of the receiving channel, so as to maximize the overlapping of the biased restricting member within the receiving channel. Further, it may be preferred to have two or more separate biased r
Gutschmit Alan
Pernick Bruce M.
Renda Philip
Alston & Bird LLP
Monarch Knitting Machinery Corp.
Worrell Danny
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