CIRCULAR KNITTING MACHINE FOR THE PRODUCTION OF TUBULAR ARTICLES

Abstract

A circular hosiery knitting machine (1) comprising a needle cylinder (2) that can be driven with a rotary motion about its own axis (2a), arranged vertically, and on whose skirt there is a plurality of axial grooves (3), each housing a needle (4), a tubular body (5) that is arranged internally and coaxially to the needle cylinder (2) and that is adapted to receive the produced article (40) during its formation; the tubular body (5) is supported so that it can slide along an axial direction within the needle cylinder (2) in order to pass from at least an inactive position, in which it is arranged with its upper end at the same level or at a lower level with respect to the upper end of the needle cylinder (2), to at least an active position, in which it protrudes with its upper end from the upper end of the needle cylinder (2).The machine (1) further comprises drive means (10) that act on demand on the tubular body (5) in order to drive its axial movement with respect to the needle cylinder (2), the drive means (10) being associated with means for controlling the speed of the tubular body (5) throughout its axial movement from the inactive position to said at least one active position.

Description

CIRCULAR KNITTING MACHINE FOR HOSIERY PRODUCTION OF TUBULAR ARTICLES The present invention relates to a circular knitting machine for hosiery for the production of tubular articles. In particular, the tubular articles produced are intended to be transferred to a station for sewing or forming loops to close one of the axial ends thereof. In the field of production of knitted articles with circular knitting machines for hosiery or similar, in some cases there is therefore a need to transfer the produced article from the machine used for the production of the article to another production unit in order to perform additional work on the produced article that cannot be done on that machine or that is not economically convenient to do on that machine. In particular, in the field of hosiery production, techniques have been developed in recent years for automatically closing the toe by stitching or looping. Some of these techniques involve removing the finished item from the production machine and transferring it to a separate workstation for further processing. At this workstation, the toe of the hosiery item is closed while the production machine continues to produce another item. These techniques offer the advantage, compared to those that close the toe of the hosiery item directly on the production machine, of not significantly impacting machine productivity. The transfer of the hosiery article, or more generally the tubular article, from the machine used for its production to the station where the closure of an axial end of the produced article has to be carried out, or more generally additional work on the produced article, is generally done by means of a withdrawal device which, by means of withdrawal elements, engages individually with the knitting loops of the produced article from the needles of the machine and holds them during the transfer of the produced article. In some techniques for closing the toe of hosiery articles, the withdrawal device is also used to support the produced article during the execution of the additional work, whereas in other techniques the withdrawal device is only used to perform the transfer of the produced article since, once it reaches the station where the additional work has to be carried out, it releases the knitting loops, previously withdrawn from the needles, to another device that has the function of supporting the produced article during the execution of the additional work, such as, for example, a handling device. This handling device arranges the loops belonging to one half of the knitting path received by the take-up device so that they face the loops belonging to the other half of the same knitting path and supports the two partial knitting paths in a mutually facing position during the operation of a sewing head or loop-forming head that joins the mutually facing pairs of knitting loops. In some known take-up devices used simply to transfer the produced article from the producing machine to a handling device, the coupling between the take-up elements and the needles, for the purpose of transferring the knitting loops from the needles to the take-up elements, is usually achieved by inserting the needle head into a seat formed at the end of the take-up element.For this reason, the withdrawal device usually features an annular withdrawal body, which is designed to face coaxially the end of the needle cylinder from which the needle heads protrude and supports a plurality of withdrawal elements oriented parallel to the axis of the withdrawal body. Such a withdrawal device is described, for example, in document EP0942086. Retraction devices are also known, described, for example, in document EP2250306, comprising an annular retraction body that supports retraction elements that can slide along radial directions relative to the retraction body. The retraction body can be arranged coaxially around the needle cylinder of a circular knitting machine, with each retraction element positioned to face a corresponding needle of the machine laterally.At the additional workstation, there is a handling device with an annular body arranged so that its axis is vertical. The annular body has, on its underside, a plurality of points arranged along an imaginary cylindrical surface whose axis coincides with and extends parallel to the axis. The points are uniformly spaced around the axis by an angular separation corresponding to the separation between the retraction elements of the retraction device.In practice, each withdrawal element is matched to a tip of the handling device and, when the withdrawal device is disposed of at the station for further work, the withdrawal body of the withdrawal device is in a coaxial position with respect to the body of the handling device with the withdrawal elements arranged around the annular arrangement of annular portion of tips and with each withdrawal element radially aligned with a tip. In the transfer of knitting loops from the needles to the gripping elements of the transfer element, there is a perceived need to be able to actuate a movement of the knitting loops along the needles while they are held in a stationary position or when they are moving relative to the knitting loops. The known machines have, internally and coaxially to the needle cylinder, a tubular body (also known as a chalice) designed to receive the product during its formation. The upper end of the tubular body is preferably widened like an inverted cone. The tubular body emerges from a lower region of the needle cylinder and can be connected, in a manner known to itself, to a suction device in order to aspirate the product during its formation. The tubular body is supported so that it can slide along its axis, which coincides with the axis of the needle cylinder, by the machine's support structure, and there are drive means that act on demand on the tubular body in order to drive its axial movement with respect to the needle cylinder. The tubular body can be moved, in particular, on demand along its axis which coincides with the axis of the needle cylinder from an inactive position, in which it is arranged with its upper end at the same level or a lower level with respect to the upper end of the needle cylinder, to at least an active position, in which it protrudes with its upper end from the upper end of the needle cylinder. In currently known solutions, the drive means that act on demand on the tubular body in order to drive its axial movement from the inactive position to one or more active positions are conveniently constituted by at least one fluid-driven cylinder with a vertical axis, which is mounted on a support element and acts with the rod of its piston on a flange that is integral with the tubular body. The solution described above, although widely used, is not without its drawbacks. In particular, the movement of the tubular body by means of a fluid-driven cylinder causes an extremely rapid rise of the produced article along the needles, which can cause, in some methods of operation, a less than perfect mutual arrangement between the needles and the loops in the stage for preparation for transfer, with consequent defects in the produced article. In particular, the extremely rapid rise of the produced article can, in some situations and with certain types of yarn, cause an incorrect mutual arrangement between the loops and the transfer elements, effectively jeopardizing the transfer of the produced article. The purpose of the present invention is to provide a circular knitting machine for hosiery for the production of tubular articles that can improve the prior art in one or more of the aspects mentioned above. Within this purpose, one objective of the invention is to provide a circular knitting machine for hosiery for the production of tubular articles that allows managing the rise of the tubular body according to the type of product and the yarn used. Another objective of the invention is to provide a circular knitting machine for hosiery for the production of tubular articles that is highly reliable, relatively easy to provide, and cost-competitive. This purpose and these and other objectives that will be made clearer below in this document are achieved by means of a circular knitting machine for hosiery for the production of tubular articles according to claim 1, optionally provided with one or more of the features of the dependent claims. The additional features and advantages of the invention will become clearer from the description of a preferred, but not exclusive, embodiment of the circular hosiery knitting machine for the production of tubular articles according to the invention, illustrated by way of non-limiting example in the accompanying drawings, in which: Figure 1 is a schematic axial sectional view of the tubular body and its drive means of the machine according to the present invention; Figure 2 is a side elevation view of the machine portion of Figure 1; Figure 3 is an enlarged scale view of a detail of the upper end of the needle cylinder of the machine according to the invention in an operating state; Figures 4 to 6 are views of the same detail as Figure 3 in another operating state. With reference to the figures, the machine according to the invention, generally designated by reference number 1, comprises, in a manner known in itself, a needle cylinder 2, which can be driven with a rotary motion around its own axis 2a, which is vertical, and on whose skirt there is a plurality of axial grooves 3, each of which houses a needle 4 which can be driven along the corresponding axial groove 3 in order to produce knitting. Internally or coaxially with respect to the needle cylinder 2, there is a tubular body 5 designed to receive the produced article 40 during its formation. The upper end of the tubular body 5 is preferably wider like an inverted cone. The tubular body 5 exits in a lower region of the needle cylinder 2 and can be connected, in a manner known in itself, to a suction device in order to aspirate the produced article 40 during its formation. The tubular body 5 is supported, so that it can slide along its axis which coincides with axis 2a, by the machine support structure and there are first drive means 10 that act on demand on the tubular body 5 in order to drive its axial movement with respect to the needle cylinder 2. The tubular body 5 can be moved on demand along its axis which coincides with axis 2a, with respect to the needle cylinder 2, from an inactive position, in which it is arranged with its upper end at the same level or a lower level with respect to the upper end of the needle cylinder 2, as shown in Figure 3, to at least an active position, in which it protrudes with its upper end from the upper end of the needle cylinder 2, as shown in Figures 4, 5 and 6. Preferably, the tubular body 5 can be moved on demand from the inactive position to multiple active positions, in which it protrudes with its upper end from the upper end of the needle cylinder at mutually different degrees. As an example, Figure 4 shows a first active position of loaded mesh, Figure 5 shows a second active position of dropped mesh, and Figure 6 shows a third active position of heel deviation. More particularly, around a lower part of the tubular body 5 that is arranged below the needle cylinder 2 there is a support element 11 that is integral with the machine's support structure, at least with respect to its translation along axis 2a, and is traversed by a cylindrical seat lia, with an axis coinciding with axis 2a, which supports, to allow sliding along its own axis, the tubular body 5. The drive means 10 are associated with means for controlling the speed of the tubular body 5 along its axial movement from said inactive position to said at least one active position. In particular, the drive means 10 comprise motor means 12 adapted to drive in a controlled manner the axial movement of the tubular body 5 from the inactive position to said at least one active position. Conveniently, the control means are adapted to control the speed of the tubular body 5 throughout its axial movement from the inactive position to said active position as a function of the corresponding rotational speed of the cylinder during the needle-raising stage. According to one possible practical implementation, the control means are associated with programming means. The control means may also be associated with sensor means associated with the needle cylinder 2 and adapted to control the motor means 12 based on the position of the needles 4. According to one practical embodiment, the motor means 12 comprise an electric motor having an output shaft 12a consisting of a worm gear that meshes with a block 13 that is integral with the tubular body 5. Different means of connection can be provided between the motor means 12 and the tubular body 11, which are adapted in any case to allow a controlled movement of the tubular body 5 from the inactive position to at least one active position. The operation of the machine according to the invention, with respect to the movement of the tubular body 5, is as follows. During normal operation of the machine, the tubular body 5 is in the idle position, shown in Figure 3, i.e., with its upper end arranged substantially at the same level or a lower level with respect to the level of the upper end of the needle cylinder 2. When it is desired to exert on the produced article 40 an action that is directed upwards to cause its ascent along the needle 4, such as, for example, when it is desired to transfer the loops arranged on the needles 4 from the needles 4 to the gripping elements of a transfer element, as described above, it is possible to actuate the motor means 12, which cause the tubular body 5 to rise at a controlled speed and in the desired amount. Figures 4 to 6 show three different degrees of rise of the tubular body 5 with respect to the needle cylinder 2. When it is desired to return the tubular body 5 to the inactive position, it is sufficient to operate the drive means in the opposite direction. By way of example, with reference to the type of machine shown in the figures, at the end of the knitting of the produced article 40 all the needles 4 are in the so-called floating mesh or under platen position (figure 3) and the tubular body 5 is in its lowest position, the one used during the knitting of the produced tubular article 40. This position is substantially common to all types of machines that perform procedures intended to perform a closed toe with withdrawal for sewing on devices external to said machine. At this point, a cam reaches the active position and begins to raise the needles 4, taking them to the loaded mesh position (Figure 4). According to the present invention, the drive means 10 are actuated, in a controlled manner, in order to raise the tubular body 5 to maintain the loops in a safe state. In fact, if the loops are too low at this stage there is a risk that they may end up under the tongue, while if they are too high they may slip off the head of the respective needle 4. Once the leveling is completed in the loaded mesh position, another cam is actuated and moves needles 4 to the dropped mesh position (Figure 5). During this stage, the tubular body 5 continues its movement at a controlled speed in order to maintain the knitting loops in the state described above. Once the leveling in the dropped mesh position has been completed, it is possible to provide for the activation of another cam in order to move needles 4 to the heel deflection position (Figure 6). If the heel deflection position is actually provided, the tubular body 5 is further actuated in order to perform an upward movement at a controlled speed to maintain the knitting loops in the state described above. When all 4 needles are in the heel deflection position, the intervention of the tubular body 5 necessary to maintain the knitting loops in the transfer position is completed. The sequence of needle movements 4 described above is merely an example, although most machines 1 that provide tubular product transfer perform substantially the same sequence except, in some cases, for the movement in the heel deflection position. Although the machine according to the invention has been conceived, in particular, to simplify and increase the speed of operations for the automated transfer of a product from the circular knitting machine that produces it to a machine that can perform the stitching or looping to close an axial end of said product, particularly for the production of hosiery articles, it can in any case be used advantageously in any situation that requires a movement of the product along the needles with which it is hooked. In practice, it has been found that the machine according to the invention fully achieves the intended purpose and objectives, since, by allowing the produced article to be moved along the shaft of the needles to which the produced article is attached, it simplifies and increases the speed of the operations for the automated transfer of the produced article from the knitting machine to a transfer element that is to be used to perform, externally with respect to said machine, the sewing and looping operation to close an axial end of said produced article. The invention conceived in this way is susceptible to numerous modifications and variations, all of them within the scope of the attached claims; moreover, all details can be replaced by other technically equivalent elements. In practice, the materials used, provided they are compatible with the specific use, as well as the contingent shapes and dimensions, can be any according to the requirements and the state of the art. The descriptions in Italian Patent Application No. 102020000006142 from which this application claims priority are incorporated herein by reference. When technical features are mentioned in any claim followed by reference signs, these have been included for the sole purpose of increasing the intelligibility of the claims and therefore such reference signs have no limiting effect on the interpretation of each element identified by way of example through such reference signs.

Claims

1. A circular hosiery knitting machine (1) comprising a needle cylinder (2) that can be driven with a rotary motion about its own axis (2a), arranged vertically, and on whose skirt there is a plurality of axial grooves (3), each housing a needle (4), a tubular body (5) that is arranged internally and coaxially to said needle cylinder (2) and that is adapted to receive a produced article (40) during its formation, said tubular body (5) being supported so that it can slide along an axial direction within said needle cylinder (2) in order to pass from at least an inactive position, in which it is arranged with its upper end at the same level or at a lower level with respect to the upper end of the needle cylinder (2), to at least an active position, in which it protrudes with its upper end from the upper end of the needle cylinder (2),Accelerating means (10) are provided that act on demand on said tubular body (5) in order to actuate its axial movement with respect to said needle cylinder (2), characterized in that said actuating means (10) are associated with means for controlling the speed of said tubular body (5) throughout its axial movement from said inactive position to said at least one active position.

2. Circular machine (1) according to claim 1, characterized in that said drive means (10) comprise motor means (12) adapted to drive in a controlled manner the axial movement of said tubular body (5) from said inactive position to said at least one active position.

3. Circular machine (1) according to one or more of the preceding claims, characterized in that said control means are adapted to control the speed of said tubular body (5) throughout its axial movement from said inactive position to said at least one active position as a function of the corresponding rotation speed of the needle cylinder (2) during the needle raising stages (4).

4. Circular machine (1) according to one or more of the preceding claims, characterized in that said control means are associated with programming means.

5. Circular machine (1) according to one or more of the preceding claims, characterized in that said control means are associated with sensor means associated with said needle cylinder (2) and adapted to control said motors (12) according to the position of said needles (4).

6. Circular machine (1) according to one or more of the preceding claims, characterized in that it comprises means for transferring said produced tubular article (40) to a station for sewing or forming loops to close one of the axial ends thereof.

7. Circular machine (1) according to one or more of the preceding claims, characterized in that said at least one active position comprises a first active position of loaded mesh and a second active position of dropped mesh.

8. Circular machine (1) according to one or more of the preceding claims, characterized in that said motor means (12) comprise an electric motor having an output shaft (12a) comprising a worm gear that meshes with a block (13) that is integral with said tubular body (5).

Images