US3377823A - Needle cylinder assembly for knitting machines - Google Patents

Description

A ril 16, 1968 'J. J. MCDONOUGH NEEDLE CYLINDER ASSEMBLY FOR KNITTING MACHINES 2 Sheets-Sheet 1 Filed Feb. 16, 1966 F l G.

INVENTOR JOHN J. McDONOUGH Z 7 7 AMA ATTORNEYS April 16, 1968 J. J. MODONOUGH 7 3,

NEEDLE CYLINDER ASSEMBLY FOR KNITTING MACHINES Filed Feb. 16, 1966 2 heets-Sheet 2 FIG. 3. INVENTOR JOHN J. MCDONOUGH ATTORNEYS United States Patent 3.377,823 NEEDLE CYLINDER ASSEMBLY FOR KNITTING MACHINES John J. McDonough, Laconia, N.H., assignor, by mesne assignments, to Scott & Williams, Inc., Laconia, N.H., a corporation of Delaware Filed Feb. 16, N66, Ser. No. 527,993 4 Claims. (Cl. 66115) ABSTRACT OF THE DISCLOSURE Needles are maintained in accurate relationship to each other and to sinkers by a slotted ring located above the upper ends of the needle cylinder slots, and supported against movement in an axial direction by a wear ring and by horizontal projections of the sinkers. The slotted ring is not secured to any other part of the needle cylinder assembly, but its circumferential and radial positions are maintained solely by the locations of the needles in its slots.

This invention relates to a needle cylinder assembly for knitting machines and particularly to the provision of means located at the top of the needle cylinder to provide accurate location of the needles by support thereof at as high a level as possible.

Circular knitting machines for ladies seamless hosiery involve extreme precision in construction to provide corresponding precision in the uniformity of the fabric produced. Typically, such hosiery involves knitting of synthetic monofilament yarns of denier, or corresponding multifilament yarns, having cross-sectional diameters of less than 0.002 inch. Four hundred or more latch needles having thicknesses of 0.013 inch, or less, reciprocate in closely spaced slots in cylinders typically of 3% inch diameter or less. A complementary sinker ring having slots corresponding in number tothe needles provides for spacing of sinkers which are essentially equidistant for adjacent needles.

Very minute deviations in stitch sizes or symmetry adversely aifectvthe appearance of the fabricQWhile the deviation involved in a single stitch might not be noticeable, when a group of corresponding stitches extending walewise in the fabric involve similar deviations, the effect is the production of vertical streaks which are easily noticeable, the effect being that of producing a vertical panel in the fabric having a density differing from that of adjacent portions of the fabric. Many factors may contribute to the production of such streaks. Nonuniformity of needles is one of these, correctible only by precision in needle manufacturing which is attainable despite the minute dimensions involved. Other factors, however, involve various deviations in the relative locations of needles with respect to each other and with respect to associated sinkers. While high precision in the spacing of needle slots may be achieved, one trouble inherent in the usual machines is that due to structural arrangements which are required, particularly for the guidance of sinkers, considerable lengths of the needles project without adequate circumferential guidance above the cylinder slots, and due to the small thicknesses of the needles circumferential deviations of their positions may occur resulting in variations in their relationships to adjacent sinkers. The sinkers themselves are far more rigid than the needles and are guided both exteriorly and interiorly of the needle circle, and the sinkers may be very accurately formed and generally do not in themselves contribute to the irregularities in needle-sinker relationships.

The general object of the invention may be stated to be the provision of proper and accurate support of the upper portions of the needles to maintain them in accurate relationship to each other and to the sinkers. In accordance with the invention, needle guidance is effected through the use of a slotted ring which is floating in the sense that it is not secured to other parts of the needle cylinder assembly. Its dimensions are small and itmay be very accurately slotted for reception of the needles, and its accuracy is not impaired by the application of stresses which would be involved in securing it rigidly to the cylinder assembly. In effect, it is located by the needles themselves, and particularly by the average condition of the total group of needles so that any needle or needles of any small group tending to deviate from the others are forced to positions locating them in proper needle-toneedle relationships.

The achievement of this general object and of other objects relating to details of construction and operation will become apparent from the following description, read in conjunction with the accompanying drawings, in which:

FIGURE 1 is an axial section taken through a needle cylinder assembly and showing a typical needle and associated sinker in positions corresponding to knockover;

FIGURE 2 is a view similar to FIGURE 1 but showing the needle at clear height and the sinker partially withdrawn; and

FIGURE 3 is a plan view partly in section of a segment of the top assembly of the cylinder.

Most of the structure involved in connection with the invention is conventional. The needle cylinder 2 may be rotary or stationary, though for consistency of description it may be considered rotary as is usual in modern machines. Walls 4 are inserted in slots 6 in the needle cylinder to define slots in which the needles 8 reciprocate vertically. The formation of a slotted needle cylinder by the insertion of walls is well known and leads to high precision in the indexing of the needle slots. In the final formation of the cylinder the accuracy of the slots may be checked and uniformity may be achieved by slight deviations of the walls. The needles are held in the slots by one or more spring bands indicated at 10 with location of the lower ends of the needles from a radial standpoint by the cam assembly acting on their usual butts (not shown). The needles are provided with the usual hooks 12 with which cooperate the latches 14 pivoted to the needle shank structures at 16.

Because of the sinker-supporting structures involved the inserted walls must terminate at a level typically as at 18. FIGURE 1 shows a needle in What is ordinarily its lowermost knockover position, and it will be seen that even in this position a considerable portion of the needle extends above the level at 18. The condition of non-support of the needle is much worse when it is in cleared position as indicated in FIGURE 2. It will be evident that v if the lateral support of the needle terminated at 18 a needle which was bent could well have its critical portion deviating quite considerably from what would be proper and achieved by a straight needle. The most critical portion of a needle from the standpoint of stitch shape or location is the portion running from the hook down to the position of the open latch, though even the portion of the shank below an open latch may contribute to irregularity in the formation of stitches.

Continuing the matter of the structural assembly involved, a sinker ring 20 is provided, mounted on portions of the inserted walls 4. The sinker ring is accurately slotted radially at 22 to provide support and guidance for the outer ends of the sinkers 24 which are provided with actuating butts 26 operated on by conventional cams. The sinkers themselves may be of many forms for dilferent purposes as Well known in the art, typically involving nebs 28 which extend inwardly over ledges 30 over which stitches are ordinarily drawn and retained, "though the drawing of stitches may be, as is known, over or behind sinker nebs. A so-called cylinder top is provided at 32, and this has a flange portion 33 to be secured adjustably and accurately to the top of the needle cylinder through the medium of screws inserted in tapped holes 35 and through slots 37. Such type of attachment is well known and serves for fine adjustment of the cylinder top both circumferentially and angularly, the adjustment being essentially of a universal type. Slots 34 in this cylinder top receive the inner portions of the sinkers 24 and serve to align them uniformly circumferentially.

The vertical positions of the sinkers in the vicinity of the needles must be accurately maintained, and for this purpose it has been customary to secure to the cylinder top a wear ring 38 of hardened steel or some other very hard wear-resisting material. This ring actually has two functions: that of maintaining the vertical positions of the sinkers, and that of maintaining the upper ends of the needles in definite radial positions. The first function is performed by the horizontal, unslotted surface 38 of the ring, this surface providing a platform on which the edges 42 of the sinkers may slide, the edges 42 being provided by the upper boundaries of the notches 40 in the inner ends of the sinkers. The surface 38 is slightly above the bottoms of the slots 34 in the cylinder top. The sinker edges 42 are accurately straight in the arrangement shown and are accurately related to the sinker ledges 30 to define the level over which loops are drawn.

The cylindrical outer surface 39 of the ring 36 provides a backing for the needles locating their upper ends radially.

The lower boundaries 44 of the notches 40 in the sinkers are horizontal and accurately related to the edges 42. These edges 44 clear the upper surface bounding the groove 46 in the cylinder top. No provision need be made to prevent the sinkers from rocking upwardly because they are held downwardly by the fabric during knitting, their vertical position being then determined solely by the surface 38 of the wear ring.

The construction so far described is conventional, but it will be evident that it does not provide lateral (circumferential) restraint on the needles above the upper ends 18 of the inserted cylinder walls. It has been proposed to provide the wear ring 36 with radially extending slots in which the needles are guided (Patent 2,154,384). This expedient, however, has not been satisfactory for several reasons: the wear ring 36 must be tightly secured to the cylinder top and its slots provided as just mentioned must be very accurately related to the slots 34 in the cylinder top. In view of the large number of slots required, it is not practical to maintain accurate relationship throughout the circumference, and in some region it is substantially inevitable that there would not be undesired deviations from a proper relationship; secondly, it will be evident that the pivot of the latch and the portion of the needle slotted for movement of the latch would be obliged to move within the slots in the wear ring during operation as indicated in FIGURE 1. Since this region of the needle is very difficult to hold to a close dimensional tolerance the slots would necessarily be sufliciently wide to provide smooth and free movement for the thickest needle which would be involved, the result being that for some needles there would be substantial play.

In accordance with the present invention needle guidance is provided by a ring 48 provided with slots 50 in which the needle move, the ring 48 being located below the wear ring 36 with a vertical clearance 52 between it and the Wear ring and with a circumferential clearance 54 between it and the cylinder top. The ring 48 is supported on the edges 44 of the sinkers.

So far as this relationship to elements rigidly connected to the cylinder is concern ill? ring 48 is float ing, i.e., it is completely unrestrained by these, and in the absence of needles would have free circumferential and radial movements. Thus there exists no placement in dependence on the parts mentioned and, in particular, no stresses are imparted thereto by connections, which stresses might involve some asymmetry of its shape. The ring, having small thickness, may have its slots very accurately indexed about its circumference. From FIG- URE 1 it will be noted that the top of the ring 48 is at all times below the latch pivot 16 of a needle, and therefore located within the slots 56 are only portions Of needles which may be held accurately to thickness dimensions. The slots 50 may, therefore, be larger than the needle thickness only by a small dimension involving the minimum clearance for free sliding movement.

While the ring 4-8 is floating with respect to the parts secured to the needle cylinder, its position is nevertheless maintained very accurately by the needles themselves. Assuming that the majority of the needles are properly spaced, when the assembly is made, the slots 50 being accurately indexed, it will be evident that those needles which might ordinarily deviate from proper angular relationship will be sprung into a uniform angular relationship. The condition which maintains the position of the ring 48 is thus dependent on what might be considered the majority of the needles. While there is a clearance 54 and merely viewing FIGURE 1 it might seem that the ring 48 could move to the right or left as viewed in the plane of that figure, giving consideration to a group of needles spaced from that shown it will be evident that such group of needles will prevent the possibility of the movement just referred to, i.e., it could not occur except with flexure of a large number of needles which, being reasonably guided by the cylinder walls are not free to flex to any appreciable extent. In summary, the ring 48 is thus quite fixedly, though theoretically flexibly, maintained in definite position, with its primary achievement being the maintenance of all of the needles in accurate circumferential relationship to each other. It is this relationship to each other and uniform relationship to the sinkers which is important. While elforts are ordinarily made to insure, particularly by adjustment of the sinker top, that the sinkers are uniformly spaced from the needles which flank them, this is actually not highly important. Even if all of the sinkers, evenly spaced from each other, were shifted slightly relative to the needles so that they were closer to a needle on one side than to the needle on the other side, this circumferential asymmetry would affect all stitches in the same fashion, and while the stitches might be slightly asymmetrical, there would be no difference in stitch sizes along the circumference and streaks would not be noticeable in the fabric. This implies, of course, that the spacings between the sinkers and needles are always such as to avoid pinching of yarn, rubbing of latches, and the like.

The fact that guidance of the needles is substantially above the level 18 prevents lateral deflections, being particularly effective when the needles are in the most critical position of knockover which corresponds to the measuring of the drawn loops. Uniformity of fabric is thus achieved with a minimizing of highly critical adjustments, there being, of course, none required as between the floating ring 48 and the needle slots of the cylinder.

It will be evident that various changes in details of construction may be made without departing from the invention as defined in the following claims.

What is claimed is:

1. A needle cylinder assembly for a fine gauge circular knitting machine comprising a plurality of independently movable needles circumferentially arranged, latches on said needles, pivots pivoting said latches on said needles, a needle cylinder providing slots for the guidance of shanks of said needles, means retaining the needles in said cylinder slots, a plurality of sinkers, means fixed to the needle cylinder and slotted for the radial guidance of said sinkers, a slotted floating ring unrestrained by any fixed connection to the needle cylinder or sinker guiding means, the slots in said ring being radial and arranged to receive the upper portions of the needles guided in the cylinder slots, and means supporting said ring against movement in an axial direction and at a level at which the upper ends of its slots are approximately at the level attained by said pivots of the needle latches during knockover, the circumferential and radial positions of said ring being maintained solely by the locations of the needles in its slots.

2. An assembly according to claim 1 in which the slots References Cited UNITED STATES PATENTS 8/1937 Lawson eta1.

4/ 1939 Richter 66-107 ROBERT R. MACKEY, Primary Examiner.

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