GB2078265A

GB2078265A - Circular Knitting Machines

Info

Publication number: GB2078265A
Application number: GB8114271A
Authority: GB
Original assignee: BREMATEX SpA
Current assignee: BREMATEX SpA
Priority date: 1980-05-12
Filing date: 1981-05-11
Publication date: 1982-01-06
Also published as: IT1133568B; DE3117883A1; CS251063B2; GB2078265B; JPS575952A; IT8009430A0

Abstract

A circular knitting machine has means for knitting a heel or toe pocket with an alternating motion of the needle cylinder. On the two sides of a yarn feed, selection means 14A, 14B act on the butts 7F of jacks situated below the needles, for the selective control of the needles themselves in such a way as to effect a variation, either as an increase or decrease, in the number of operative needles. Means 10 for raising the operative needles and symmetrical means 1A, 1B for lowering the needles are used for the formation of a pocket, with rows of stitches of variable length. A single yarn guide is moved alternately between two positions 4A, 4B at each reversal of the needle cylinder. <IMAGE>

Description

SPECIFICATION Circular Knitting Machines The present invention relates to circular knitting machines and more particularly to machines for producing hoisery such as stockings or socks with a pocket for the heel and toe or the like, with alternating motion of the needle cylinder.

Heel pockets produced with alternating motion of the needle cylinder are usually made with the use of so-called pickers which are oscillating elements able to collect the first or the first two butts of jacks or operative needles to make them inoperative and, respectively, to make them operative again. This arrangement requires the use of rings for the protection of the latches of the needles raised into an inoperative position by projecting upwards relative to the area of operation of the needles. The presence of the pickers usually requires the speed to be reduced, in order to limit the breakage of the needles and pickers, and also because of the danger of breaking of the needles protruding into the operative area.The arrangement also necessitates substantial space around the operative area of the needles, and therefore causes difficulties in access for inspection, maintenance and replacement of parts. Also, difficulties arise when working with more yarn feeds.

Although the previously proposed system does have disadvantages as discussed above, a fabric having pockets knitted with alternating motion of the needle cylinder is considerably better than that knitted with a continuous rotational motion of the needle cylinder.

According to the invention, there is provided in a circular knitting machine of the type having a needle cylinder which operates with alternating motion, needles carried by the needle cylinder, selection butts, a yarn feed, a yarn guide at said yarn feed, and means for forming a heel or toe pocket, said means comprising, on two sides of said feed, selection means acting on said selection butts for the selective control of the needles in such a manner as to bring about a variation in the number of needles in operation, means for raising the operative needles, symmetrical means for lowering the needles for forming a pocket with rows of stitches of variable length, and means for moving said yarn guide into a respective one of two positions at each reversal in the direction of movement of the needle cylinder.

The variation in the number of operative needles can either be an increase or a decrease.

The selection means and the butts upon which said means act may be substantially symmetrical relative to a central position.

The means for lowering the needles for the formation of the stitch-which are symmetrical relative to a central position to which the two positions reached by the yarn guide are also symmetrical-preferably exhibit an intermediate horizontal stepped portion in each of the operative lowering profiles. The two positions of the yarn guide correspond to such stepped portions.

In one embodiment, the selection means comprise rocking jacks and push-type selection blades, with the butts of the jacks being at several levels. At each level provision is made for an arc without butts, of an amplitude different from that of the arcs of the other levels.

In another embodiment, the selection means comprise lifting jacks, the selection jacks of which cooperate with radial blades. Provision may be made for butts of several lengths and blades with several insertion positions.

The means for forming the heel and toe pockets can be disposed at one or more yarn feeds.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows the development of a cam assembly facing a yarn feed, for the control of the needles for the formation of a pocket for a heel or the like; Figure 2 is an enlarged view of a portion of the development of Figure 1, to show the conditions existing during movement of the needle cylinder in one direction; Figure 3 is a vertical section showing a rocking jack and a corresponding needle; Figure 4 shows part of the development of Figure 2 to show the conditions existing during movement of the needle cylinder in the reverse direction; and Figures 5 and 6 shows a system for controlling the yarn guides.

As illustrated in the drawings, A-A denotes a line of symmetry corresponding to a yarn feed, facing which are means for controlling the formation of the pocket, as described hereinafter.

1 A and 1 B denote two cams which are symmetrical and abut the line A-A for lowering the needles and countercams 2A and 2B are associated with the cams 1 A and 1 B respectively.

The operative profiles of the two cams 1 A and 1 B include stepped sections 3A and 3B. 4 denotes a yarn guide which may be moved between two symmetrical positions 4A and 4B on opposite sides of the line A-A and which corresponds to the two stepped portions 3A and 3B.

5 denotes the needles and 7 the jacks which are used for controlling the lifting of the needles by means of selection devices to be described.

The lowering of the needles is effected by means of needle butts 5A which cooperate with the cams 1A and 1 B.

In the embodiment described, the jacks 7 are of the rocking type which rock about a point 7A on the bottom of the associated longitudinal groove formed in the needle cylinder. 7B shows a jack lowering butt cooperating with a lowering cam profile 9 which has two symmetrical ramps 9A and 9B. 7C denotes a jack lifting butt 7, with a slightly inclined profile, which is able to cooperate with a cam profile 10 and in particular with lifting ramps 1 OA and 1 OB thereof when the relevant jack has been selected to operate. 1 2A and 1 2B denote two pusher cams, intended to act on the rear of a tail piece 7E of the rocking jacks 7 to push the lower part of the relevant jack outwards and therefore towards the cam profile 1 0. By this means there is produced the lifting of the jack and therefore of the needle, unless there occurs a jack exclusion action brought about by one or the other of a plurality of selection butts 7F which may be removed according to the arrangement required by the necessary selection pattern for the needles. The butts 7F are disposed in a plurality of rows and can be engaged by latches of one or other of two symmetrical groups 1 4A and 1 4B of radially movable selector latches or blades.When a latch 14 pushes an incoming jack 7 (after the latter has been made to protrude by the appropriate cam 12) this jack is excluded from the possibility of being lifted by the action of the cam 10 on the butt 7C, and therefore the corresponding needle is excluded from lifting.

In the right-hand section when locking at Figure 1 of the drawing, there is shown an arrangement of butts 7F on various levels to obtain a pocket for the heel or for the toe in a stocking fabric; it will be noted from this arrangement that the rows of butts at the various levels exhibit missing butt arcs which differ one from the other, with an arrangement on the cylinder which is substantially symmetrical relative to an axis Al-Al to obtain the formation of the pocket by means of rows of stitches of a length corresponding to the missing butt arcs.

With this arrangement a selection control is operated by the selector latches 1 4A and 1 4B which operate alternately in the two directions of the oscillation of the needle cylinder, to control the butts 7F and therefore to select the jacks and the needles. In this way there is obtained a deliberate distribution of the rows of stitches of various lengths and the formation of the pocket, through an alternating movement of the needle cylinder.

During the movement of the needle cylinder in one direction, indicated by the arrow F2 of Figure 2, cams 1 2A, 1 4A, 1 OA, 1 A, 3A, and 2A cause the needles to follow a path shown by the line TA of Figure 2, the yarn guide 4 being in position 4A.

During the movement of the needle cylinder in the reverse direction, shown by arrow F2 of Figure 4, cams 1 2B, 1 4B, 1 OB, 1 B-3B and 2B cause the needles to follow a path indicated by line TB of Figure 4, the yarn guide 4 being in position 4B.

The yarn guide 4 may be moved by any suitable control means synchronised with the reversal in the movement of the needle cylinder.

For example, it is possible to use the angular displacement undergone by a cover of plates 20 or each reversal of the movement of the needle cylinder. For example, it is possible to provide two rollers 22 fixed on the cover 20 to move the yarn guide 4 between position 4A and position 4B, the yarn guide being hinged at 24 for example on a plate 26 which bears a latch-opener plate 28.

With the knitting machine particularly described, heel or toe pockets for socks and women's stockings, can be obtained with particular simplicity and reliability of operation and also with high operating speed, despite the use of an alternating motion of the needle cylinder to knit the pocket.

Claims

1. A circular knitting machine comprising a needle cylinder which operates with alternating motion, needles carried by the needle cylinder, selection butts, a yarn feed, a yarn guide at said yarn feed, and means for forming a heel or toe pocket, said means comprising, on two sides of said feed, selection means acting on said selection butts for the selective control of the needles in such a manner as to bring about a variation in the number of needles in operation, means for raising the operative needles, symmetrical means for lowering the needles for forming a pocket with rows of stitches of variable length, and means for moving said yarn guide into a respective one of two positions at each reversal in the direction of movement of the needle cylinder.

2. A circular knitting machine according to claim 1, wherein the selection means are substantially symmetrical about a central position.

3. A circular knitting machine according to claim 1 or claim 2, wherein the butts are substantially symmetrical about a central position.

4. A circular knitting machine according to any one of claims 1 to 3, wherein the means for lowering the needles for formation of the stitches comprise lowering profiles symmetrical about a central position, each lower profile having means defining a stepped horizontal intermediate portion, the two positions of the yarn guide corresponding to said stepped portions.

5. A circular knitting machine substantially as hereinbefore described with reference to the accompanying drawings.