DESCRIPTION

The present invention relates to a special structure of a sinker for a knitting machine, a knitting machine, in particular, but not only, a circular inlay knitting machine with alternating motion of the needle cylinder, a method for producing a knit stitch with said sinker, and a patterned terry knit article produced by a knitting machine that uses said sinker.

A preferred but not exclusive field of application relates to the production of shoe uppers, particularly, but not necessarily, on multi-feed circular inlay machines with a needle cylinder actuated with alternating motion.

As is well known, a sinker is a member in the form of a shaped plate that contributes to the formation of a knit stitch together with the needle.

The use of circular knitting machines of the above-mentioned type is known, but may pose the drawback, especially in the event that they have a small diameter, of limiting the number of models of shoe uppers that can be produced.

The technical task of the present invention, therefore, is to make it possible to produce a wide range of models of a knit article also with a knitting machine of limited size.

Within the scope of this technical task, one object of the invention is to provide a sinker structured in such a way as to produce, also with a knitting machine of limited size, a knit article with different smooth knit areas joined together which can also have a selectable thickened knit area within them, in particular, but not necessarily, a selectable terry knit area.

Another object of the present invention is to provide a sinker that can be used in a multi-feed circular inlay knitting machine having a small diameter and a needle cylinder actuated with alternating motion to produce a shoe upper, in particular a patterned terry shoe upper.

The technical task as well as this and other objects are achieved by a sinker for a knitting machine, characterised in that it has a body with a variable configuration comprising a first shaped plate and a second shaped plate which are coplanar and structurally independent and movable relative to each other, wherein the first plate has a first heel for taking up movement and at least a first knit stitch knock-over surface and the second plate has a second heel for taking up movement and at least a second knit stitch knock-over surface, wherein the first and the second plate have the same maximum thickness and at least one portion with a reduced thickness, wherein the first and second plates intersect in the portion thereof with a reduced thickness, and wherein the sum of the value of the reduced thickness of said first and second plates is not greater than the value of the maximum thickness of said first and second plates.

In one embodiment said portions with a reduced thickness of said first and second plates may have the same thickness.

In one embodiment at least one between the first and second plates has a selection heel.

In one embodiment at least one between the first and second plates has a rest surface for the knit stitch.

In one embodiment said first and second plates have conjugate linear sliding guide portions.

In another embodiment, said first and second plates are reciprocally constrained with a possibility of relative rotary movement or combined linear and rotary movement.

In one embodiment at least one between said first and second plates has a flexible finger for disengageable engagement with a retaining element in a reference position.

In one embodiment said first and second plates are metal plates produced by chemical photoengraving of flat sheets.

The present invention also discloses a knitting machine, provided with such a sinker.

In one embodiment, the knitting machine is circular, the needle cylinder and the crown are coaxial and solidly joined and have an alternating rotary motion, and mounted above the crown with radial slits there is a cover which is oscillatable relative to the crown, about the axis of the crown, said cover having a first track in which the first heel for taking up the radial movement of the first plate engages along the radial slit and a second track in which the second heel for taking up the radial movement of the second plate engages along the same radial slit, and at least one between the first and second tracks has selectable paths.

The paths can also be selected for sinkers individually.

In one embodiment, at least one between the first and second tracks has cams for selecting the path which interact with said at least one selection heel.

The present invention also discloses a process for producing a knit stitch with such a circular inlay knitting machine, wherein the sinker operates on at least two yams and is programmed to selectively form a smooth knit stitch on the first or second knock-over surface by the selective advancement of said first or second plate towards the needle cylinder and a terry knit stitch on the first and second knock- over surfaces by synchronised advancement of said first and second plates towards the needle cylinder.

Additional features and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of the sinker, the knitting machine and the method for producing a knit stitch according to the invention, illustrated by way of non-limiting example in the appended drawings, in which: figure 1 shows a top perspective view of the crown of the sinkers of a four-feed circular inlay machine; figure 2 shows a bottom perspective view of the cover of the crown of the sinkers of figure 1 ; figure 3 shows a vertical sectional view of the crown of the sinkers of figure 1 with the sinker in position for the formation of a smooth knit stitch; figure 4 shows a vertical sectional view of the crown of the sinkers of figure 1 with the sinker in position for the formation of a terry knit stitch; figure 5a shows a side elevation view of the sinker in position for the formation of a smooth knit stitch; figure 5b shows a perspective view of the sinker of figure 5a; figure 5c shows a section of the sinker along the line 5c-5c of figure 5b; figure 6a shows a side elevation view of the sinker in position for the formation of a terry knit stitch; figure 6b shows a perspective view of the sinker of figure 6a; figure 6c shows a section of the sinker along the line 6c-6c of figure 6b.

With reference to the aforementioned figures, they show a sinker 1 that can be used in a knitting machine.

Below we will make reference to a circular inlay knitting machine comprising a rotating needle bed made up of a cylinder 20 circumferentially having axial grooves for guiding the needles, a crown 21, 22, 30 having radial slits in which the sinkers 1 slide, and four feeds, on each of which at least one yam guide (striper) is mounted to feed yam to the needles in the formation of the knit, wherein each feed comprises a system of cams for actuating the needles in the knit, loop or missed stitch position.

The field of application obviously also extends to a circular machine with a double needle bed and one or more feeds, or a rectilinear knitting machine.

The crown 21, 22, 30 is mounted fixed on the head of the needle cylinder 20 and comprises a crown element 21 outside the cylinder, a crown element 22 inside the cylinder, and a lower ring 30 locked in position by specific brackets 31.

The crown 21, 22, 30 for the sinkers 1 is coaxial and solidly joined with the cylinder 20 in alternating rotation.

The sinkers 1 are radially slidable, one for each slit in the crown 21 , 22 and, as is well known, each cooperates with a corresponding needle for the formation and knock-over of the knit stitch.

A cover 23 of the sinkers 1 is mounted above the crown 21, 22, 30.

The cover 23 is oscillatable relative to the crown 21, 22, 30 about the rotation axis of the crown 21, 22, 30 and of the needle cylinder 20. The alternating oscillation of the cover 23 relative to the crown 21, 22, 30, as we shall see, serves to bring about the radial movement of the sinkers 1 from and towards the needle cylinder 20 in proximity to the working positions, depending on whether in one rotation direction of the needle cylinder 20 or in the opposite one. The sinker 1 has a body with a variable configuration comprising a first shaped plate (2) and a second shaped plate (3) which are coplanar and movable independently from each other.

The first plate 2 has a first heel 4 for taking up movement and at least a first knit stitch knock-over surface 5.

The second plate 3 has a second heel 6 for taking up movement and at least a second knit stitch knock-over surface 7.

The first plate 2 and respectively the second plate 3 have the same maximum thickness and at least one portion 2a and respectively 3a with a reduced thickness. The first plate 2 and the second plate 3 intersect in the portion thereof with a reduced thickness 2a, 3a.

The sum of the value of the reduced thickness of the first plate 2 and the second plate 3 is not greater than the value of the maximum thickness of the first plate 2 and the second plate 3.

The maximum thickness of the sinker 1 is equal to the maximum thickness of the first plate 2 and the second plate 3.

The portions with a reduced thickness 2a, 3a of the first plate 2 and second plate 3 can have the same thickness.

At least one between the first plate 2 and second plate 3, in particular the second plate 3, has a selection heel 8. In the specific case the first plate 2 does not have a selection heel because, as we shall see, in the preferred application it is always selected, whereas the second sinker 3 may or may not be selected.

It is not ruled out that in other applications the first plate 2 as well may comprise a selection heel.

At least one between the first plate 2 and second plate 3 has a rest surface 9 for the knit stitch.

In the case shown, only the first plate 2 has a rest surface 9 for the knit stitch, but it is not ruled out that in other applications the second plate 3 as well may comprise a rest surface per the knit stitch.

The knit stitch created, by means of a selective movement of the first plate 2 relative to the needle, can be moved from the first knock-over surface 5 to the rest surface 9, wherein the tension thereof is at least partially released.

The first plate 2 and the second plate 3 can have conjugate portions 10, 11 which act as a guide for the reciprocal linear sliding.

The first plate 2 and the second plate 3 further have perimeter edges that extend longitudinally in a radial direction and slidingly engage specific walls 27 of the crown 21, 22, 30 which ensure that the sinker 1 is guided in a radial direction.

At least the selectable plate 3 has a flexible finger 24 provided with a terminal 25 for disengageable engagement with a retaining element 26 in a deselected condition.

The retaining element 26, obtained from a notch in the ring 30, assures, as we shall see, that there is no undesired selection of the second plate 3.

The flexible finger 24, in addition to an engagement and braking function, also has the function of a sliding guide for the plate 3 in the radial slit of the crown of the sinkers.

The first plate 2 and second plate 3 are advantageously metal plates produced by chemical photoengraving of flat sheets.

This process makes it possible to obtain sinkers with a very precise contour and very small thickness, especially in the zones with a reduced thickness.

The cover 23 has a first track 28 in which the first heel 4 for taking up the radial movement of the first plate 2 engages along the radial slit of the crown and a second track 29 in which the second heel 6 for taking up the radial movement of the second plate 3 engages along the same radial slit.

At least one track between the first track 28 and the second track 29 has selectable paths.

In the case illustrated, only the second track 29 has two selectable paths 29a, 29b. The second track 29, which has selectable paths 29a, 29b, is provided with cams 32 for selecting the path.

There are two selection cams 32, one operating for each direction of oscillation of the cover 23.

The two selection cams 32 are adapted to selectively interact, during an oscillation of the cover in one direction or the other, with the second heel for taking up movement 6 comprised by the second plate 3.

The cover 23 is moved in the two oscillation directions by a pneumatic piston 34 which actuates an oscillating lever 35 operatively connected to the cover 23.

For the selection of one of the two paths 29a or 29b of the second track 29, the selection heel 8 of the second plate 3 interacts with a selector device 36 of a traditional type provided for each of the four feeds.

The selector device 36 has a group of selection levers 37 which oscillate independently, each engageable with the selection heel 8 of the second plate 3 of a corresponding sinker 1 positioned in a radial slit of the crown 21, 22, 30.

The consecutive sinkers 1 in the crown 21, 22, 30 differ from one another in the position, in height, on the second plate 3, of the selection heels 8, which form a diagonal, as illustrated in figure 1 , to enable the electronic selection of the sinkers 1.

Four oscillating levers 37 intended to actuate the second plates 3 of four consecutive sinkers 1 are shown by way of example.

The first track 28 has a single path comprising a section shaped like a cam 28’ having a variable radial distance from the axis of the cover 23 and a section shaped like a circumferential arc 28” centred on the axis of the cover 23.

The first plate 2 remains radially immobile when the first heel 4 for taking up movement passes over the arc 28” and shifts radially when the first heel 4 for taking up movement passes over the cam 28’.

The first path 29a of the second track 29 comprises a section shaped like a cam 29a’ having a variable radial distance from the axis of the cover 23 and a section shaped like a circumferential arc 29a” centred on the axis of the cover 23.

The second plate 3 remains radially immobile when the second heel 6 for taking up movement passes over the arc 29a” and shifts radially when the second heel 6 for taking up movement passes over the cam 29a’.

The second path 29b of the second track 29 comprises only a section shaped like a circumferential arc 29b’ centred on the axis of the cover 23. The second plate 3 remains radially immobile when the second heel 6 for taking up movement passes over the arc 29b’.

The oscillating lever 37 has a rest position and a working position.

In the rest position the oscillating lever 37 does not move the selection heel 8. In this circumstance the second heel 6 for taking up movement remains in the second path 29b of the track 29, in which the second plate 3 is not selected.

In the working position the oscillating lever 37 slightly shifts the selection heel 8. In this new circumstance the fixed cam 32, when it intercepts the second heel 6 for taking up movement, deviates it towards the first path 29a of the track 29, in which the second plate 3 is selected.

Advantageously, with the sinker 1 it is possible to conveniently form a smooth knit stitch or a terry knit stitch with two yarns A and B and consequently with the knitting machine described above one can produce a knit article, in particular, but not only, a patterned terry shoe upper.

In fact, during the production of a same row knit with the two yams A and B the sinker 1 can selectively form a smooth knit stitch or a terry knit stitch.

The formation of the smooth knit stitch with the two yams A and B takes place in the following manner.

The cover 23 is made to oscillate in one direction relative to the crown 21, 22, 30. The selector 36 is programmed to not actuate the selection lever 37, which remains in the rest position.

The second plate 3 is consequently not selected and remains radially immobile, since the second heel 6 for taking up movement passes over the second path 29b. The retention of the second plate 3 in the unselected state is assured by the engagement of the terminal 25 of the flexible finger 24 with the retaining element 26.

The first plate 2, by contrast, carries out a radial movement towards and from the needle cylinder 20 due to the sliding of the first heel for taking up movement 4 along the cam 28’ of the first track 28.

The smooth knit stitch is created with two yams A and B on the first knock-over surface 5 and is then moved into the rest position on the rest surface 9 positioned at a lower level by means of the movement of the first plate 2.

The formation of the terry knit stitch with the two yams A and B takes place in the following manner.

The cover 23 is made to oscillate in one direction relative to the crown 21, 22, 30. The selector 36 is programmed to actuate the selection lever 37, which goes into the working position.

The second plate 3 is consequently selected and, on being disengaged from the retaining element 26, carries out a radial movement towards and from the needle cylinder 20 due to the sliding of the second heel for taking up movement 6 along the cam 29a’ of the second path 29a of the second track 29.

The first plate 2, always selected, also carries out a radial movement towards and from the needle cylinder 20 due to the sliding of the first heel for taking up movement 4 along the cam 28’ of the first track 28.

The radial movement of the first plate 2 and the second plate 3 is synchronised since the cam 29a’ and the cam 28’ are aligned in the same angular position.

The terry knit stitch is created with the yam A on the first knock-over surface 5 and the second yam B on the second knock-over surface 7. Once the work has been completed, the second plate 3 is automatically deselected pending its reselection in a next row of knit formation or on the return row or on other feeds.

Advantageously, during the process on the feeds the formation of the smooth or terry knit stitch takes place in both a clockwise and anticlockwise direction on all the feeds envisaged by the circular inlay machine.

Advantageously, the sinker 1 enters into a single slit of the crown 21, 22, 30, but with the possibility for the two plates 2, 3 to slide independently in the formation of the knit and this contributes to increasing the models of shoe uppers or another knit article which can be produced with a circular inlay machine with a small diameter.

The sinker for producing a knit stitch in a knitting machine thus conceived is susceptible of numerous modifications and variants, all falling within the scope of the inventive concept; moreover, all of the details may be replaced by technically equivalent elements.

The materials used, as well as the dimensions, may in practice be any whatsoever according to needs and the state of the art.