This invention concerns, in general, the field of the circular knitting machine for hosiery and knitwear using the needles on the dial, and, in particular, relates to the disposition of the devices for the control of the formation of the stitches by the needles on the dial.

Some single cylinder circular machines for hosiery and/or knitwear comprise a rotating cylinder, that carries a plurality of needles which are arranged and vertically movable on its periphery, and a dial positioned above the cylinder, rotating with it and carrying in turn a series of operating members, which are arranged horizontally and movable in radial grooves provided in the body of the dial on directrixes passing between the vertical needles of the cylinder.

The operating members mounted on the dial are usually in the form of hooks or needles when stitches have to be carried out; or else they are usually in the form of sinkers for terry knitting.

However it has been found that in some knitting processes with needles on the dial, difficulties and drawbacks may arise when casting off the relative stitches, creating unacceptable defects in the resulting knitting. This, in particular, when the needles on the dial have to create stitches separately from the needles of the cylinder and more particularly when different yarns are used from those made of synthetic elastomeric fibre known as Lycra or also Elastane. Furthermore, document EP0683257A discloses a knitting machine according to the preamble of claim 1.

This invention has been conceived to avoid these difficulties and drawbacks and correspondently it proposes to provide the dial needles of a hosiery and/or knitwear circular machine with auxiliary elements to facilitate the casting of the stitches from said needles independently from the type of thread being used from time to time and also, for example, to facilitate where required, the transfer of the stitches between the needles on the dial and those on the cylinder.

The objective of the invention is reached by associating each one of at least a part of the needles on the dial, with a sinker configured to interact with the hook of the respective needle during the formation and casting of each stitch, according to the features of claim 1.

The sinker may be placed alongside the respective needle, directly in the guide groove of the latter either on its left or right side. Or the sinker can be positioned separately from the respective needle, in a proper radial guide groove provided between the grooves of two consecutive needles.

In each case, then, each sinker is susceptible to oscillations in a vertical plane relatively to the associated needle between two initial and final extreme work positions and is provided with means for causing said oscillations, said means being provided to interact with cam tracks defined by the body of the dial and by a ring/cover located above the latter.

More details of the invention will however become more evident in the following description made in reference to the enclosed indicative and not limiting drawings, in which:

• Fig. 1 shows a side view of a sinker;
• Fig. 2 shows an enlarged detail of the head of the sinker, circled in Fig. 1;
• Fig. 3 shows a side view of a needle of the dial;
• Fig. 4 shows an first arrangement of the paired needles and sinkers on the body of the dial;
• Fig. 5 shows a second arrangement of the needles and sinkers on the body of the dial;
• Fig. 6 shows an inner side view of the ring/cover of the dial provided with guide and control tracks for the sinkers;
• Fig. 7 shows a sinker, and its oscillating movements, located between body and ring/cover of the dial;
• Figs. 8, 9 and 10 show as many views in cross-section respectively according to arrows "A", "B" and "C" of the whole of the dial with needles and sinkers;
• Figs. from 11 to 17 show a sequence of positions of a sinker with respect to a relative needle during the construction and casting of each stitch (the needle being reproduced frontally and overlapping the relative sinker); and
• Fig. 14a shows an enlarged part of Fig. 14.

As shown, the dial for a monocylinder circular machine for hosiery and knitwear is indicated basically by number 11. Said dial 11 carries a plurality of needles 12 and a plurality of casting-off sinkers 13, each disposed radially and horizontally and which can be equal or different in number, for example equal to half, with respect to the vertical needles on the machine cylinder and alternating with them.

The dial 11 is composed of a dial body 14 mounted and controlled, besides in a known way, to turn on a vertical axis 15 and an overlooking ring or cover 16, stationary compared to said dial body. The dial body 14 is provided with a plurality of radial grooves 17 each of which designed to receive and guide a needle 12, having a needle head 12' facing towards the periphery of the dial and comprising a hook 18 and a latch 19 for opening and closing the hook (Fig. 3). The needles 12 on the dial are susceptible to radial operating movements between two advanced and retracted extreme positions in which its head 12' is protruding and respectively retracted with respect to the periphery of the dial body. To cause these movements, each needle 12 is provided with a needle heel 20 which is engaged and compelled to move in an appropriate cam track 21 (Figs. 6 - 8) provided on the internal face of the stationary ring or cover 16 of the dial.

A needle 12 corresponds to each sinker 13. It can be placed directly in the same guide groove 17 of the needle 12 which it is associated with and at the side of the latter, as shown in Fig. 4. As an alternative, the sinker 13 can be separated from the respective needle 12 and placed in this case in an additional radial groove 17' provided in the space between the guide grooves 17 for two consecutive needles 12 as shown in Fig. 5.

In the example shown, the sinkers 13 are not movable radially on the dial, but each of them is susceptible to oscillating movements, that is balancing, in a vertical plane. Moreover each sinker 13 has a sinker head 13' facing towards, and designed to interact with, the needle head 12' of the needle 12 it is paired with.

To prevent its radial movements, each sinker 13 has a foot 22 which is radially confined but, all the same moving vertically, in a slot or recess 23 on the bottom of the guide grooves 17 or 17' in which it is housed. For its operating oscillation movements, each sinker 13 has a an intermediate oscillating fulcrum 24 and at least one control sinker heel, or better two sinker heels near their opposite ends: a first sinker heel 25 at the sinker head 13' and a second sinker heel at the tail of the sinker itself (Fig. 1).

The oscillating fulcrum 24 can be on the lower edge of the sinker 13 and find support on the bottom of the guide grove17 or 17', whereas the control sinker heels 25, 26 can be on the upper edge of the sinker 13, facing upwards and made to follow correlated cam tracks 27, 28, respectively, provided on the internal face of the stationary ring or cover 16 on the dial body 14. In order to cause effectively the oscillating movements of the sinker, the cam tracks 27, 28 have opposite courses so as to apply a vertical thrust alternatively on the first and second control sinker heels without engaging the other. In other words, where the first cam track 27 has a depression 27', the second cam track 28 has a hump 28'; on the contrary where the first cam track has a hump 27" the second cam track has a depression 28" (Figs. 6-10). This is provided so as to lower and raise the sinker head13' in order to be able to conveniently position it near or away from the needle head 12'.

As regards to the head 13'of the sinker, on its lower side (Fig. 2) it can have a thread beater plane 29 and a thread retainer nose 30 whose functions will become evident in the description that follows. On an upper plane of the dial body, along its peripheral margin, where necessary, a lowering 14' to allow the oscillating movements of the head of the sinker can also be provided.

In Figs. 11-17 is illustrated, also with the indication of the respective arrows F, G, a sequence of the oscillating movements of a casting-off sinker 13, in particular of its head 13', in relation to a respective needle 12 on the dial during a formation cycle of each stitch 31 by a thread 32 fed by a thread guide 33.

In particular, in Fig. 11 the needle 12 is in a retracted position; its hook 18, that has picked up the thread 32 for the formation of a new stitch 31, is closed by the respective latch 19; the sinker head 13' is lowered towards the head 12' of the needle 12, with its beater mechanism 29 that rests on a previously formed stitch, while its retainer nose 30 engages and retains the thread 32 in order to prevent said thread from moving away from the needle head..

In Fig. 12 the needle 12 is partially advanced from the retracted position, whereas the sinker head 13' remains lowered practically as before so that its retainer nose 30 continues to retain the thread 32 in the same way.

In Fig. 13 the needle 12 is in an extreme advanced position, in which the needle latch 19 is opened by the new stitch 31 that passes towards the back of the needle12; the sinker head 13' remains lowered always retaining the thread 32 as before, until the new stitch 31 has fully moved over the needle latch 19 and dropped behind the latter, on the shaft of the needle; the hook 18 of the needle, now open, is in the condition to pick up a new length of thread 32 for the formation of a subsequent stitch 31'.

In Fig. 14, respectively 14a, the needle begins to retract towards the download position of the new stitch 31; the head 13' of the sinker is always lowered to hold the thread 32 with its sinker nose 30; following the retraction of the needle, the stitch previously cast on the shaft of the needle, causes the latch 19 to rotate towards the hook 18 of the needle 12; and the hook of the needle has picked up the new length of thread 32 for the formation of a subsequent stitch 31'.

In Fig. 15 the needle is retracted even further in a position in which the needle latch 19 closes the hook 18 of the needle; the new stitch 31 now has to pass over the closed latch 19, falling on a previous stitch; the hook of the needle picks up and drags with it the new length of thread, forming the next stitch 31'.

In Fig. 16 the needle continues to retract, completing the dropping of the new stitch 31 on the new length of thread 32 taken from the hook of the needle, while the head 13' of the sinker 13 rises upwards disengaging the thread 32.

In Fig. 17 the needle completes its retreating movement; the retainer nose 30 of the head of the sinker 13' is on such a level as to retain the stitch 31 just dropped in position so that it does not follow the new length of thread that is picked up by the hook of the needle for the formation of the subsequent stitch 31'.

At this stage the formation cycle of a stitch 31 using the needles on the dial is completed and the operating sequence of the sinker just described will then be repeated for each subsequent stitch.