Method and device for producing tubular knitted articles and for closing their toes

Abstract: According to the method, a tubular article (M) is knitted by a circular needle bed (5) from said starting edge (B1) to a terminal edge (B2) designed to form a closed toe. According to the method, an elastic strip (F1) is formed by the needles along said terminal edge. When the elastic strip (F1) has been formed, the tubular article is fully released from the needles (5) of the circular needle bed and is engaged by means of said elastic strip with a transfer member (21) for transferring the completed tubular article out of the circular needle bed.

Description: Technical field The present invention relates to methods and devices for use in the field of stocking manufacture and generally in the field of knitting tubular articles, such as stockings and socks, which have one end closed to form a toe. In a first aspect, the invention relates to a method and device for removing the tubular article from the circular needle bed of the knitting machine in order to allow the subsequent sewing of the terminal edge to form the closed toe of the article. In a further aspect, the present invention relates to a method for the production, on circular knitting machines, of tubular articles, for example stockings or socks, which can be easily handled at the time of sewing of the toe. State of the art In the production of tubular knitted articles, such as stockings, tights, socks, and others, the article is normally knitted on a circular needle bed, to form a product consisting of a tube of knitted fabric open at the ends. This tube is then sent to sewing machines where the terminal edge is sewn to produce the closed toe of the finished article. The sewing requires a considerable amount of labour, since each tube of knitted fabric has to be picked up manually, and its flaps have to be brought together and tensioned and then inserted into what is known as the guillotine of the sewing machine. It is extremely difficult to automate this operation, since only the human hand is capable of correctly bringing together and tensioning the flaps of the terminal edge of the tube of fabric and inserting them into the sewing machine. Some attempts have been made to achieve the closing of the toe directly on the circular knitting machine. These are described, for example, in EP-A-0592376, EP-A-0635593. Other systems are described in WO-A-9531595, WO-A-9534702, WO-A-9704153. In the last-mentioned, the toe is closed by starting the knitting of the tubular article from the toe itself and finishing with the elastic edge which remains open and forms the opening for putting on the article. EP-A-0679746 describes a device in which, at the end of the knitting of the tubular article, the article is partially released from the circular needle bed and gripped, at two diametrically opposite points of the terminal edge, by a pair of hooks. After the hooks have securely gripped the article, it is released from the needles. The hooks then carry the article to a pair of clamps which again grip the article at diametrically opposite points and tension the article, bringing the flaps of the edge together and then inserting them into the sewing machine. This device has considerable drawbacks, due primarily to the necessity of gripping the article on both a first and a second occasion with mechanical members which may damage the fabric. Moreover, it is not easy to insert the edge of the article into the sewing machine with the mechanical members described in the document. To facilitate the stage of the actual sewing of the toe, methods have been investigated which are based on the production of sequences of rows of knitting formed with threads having particular characteristics and/or particular dimensions of the stitches. Examples of some methods of this type are described in EP-B-0 456186. These methods do not tackle the problem of facilitating the introduction of the terminal edge of the article into what is called the guillotine of the sewing machine, or the problem of enabling this stage of processing to be mechanized. Objects of the invention A first object of the present invention is to provide a method and a device which make it possible to simplify the operations of inserting the terminal edge of the tubular article into what is called the guillotine of the sewing machine, making this operation simple and easily mechanizable. In another aspect, an object of the present invention is to provide a method and a device which make it possible to control more efficiently the edge to be sewn to form the closed toe, when it is inserted into what is called the guillotine of the sewing machine. In yet another aspect, the object of a further development of the present invention is to provide a device and a method which make it possible to mechanize the operations of sewing the toe of a tubular article. Within the scope of this further development, the object of the invention is also to provide a device and a machine which permit the simple and reliable handling of the tubular articles. Summary of the invention According to a first aspect of the present invention, a method is provided for knitting a knitted tubular article with a starting edge and a finishing toe, in which a circular needle bed knits said tubular article from said starting edge to a terminal edge intended to form said toe. According to the invention, an elastic strip, in other words a portion of elasticated fabric, designed to be removed from the article after the toe of the article has been closed by sewing, is characteristically made to be formed along the terminal edge by a suitable selection of needles in the circular needle bed. This elastic strip, having a thickness greater than that of the fabric which forms the article, extends beyond the area which will subsequently be sewn to form the toe. Its function is to make the terminal edge denser and to prevent it from tearing and from becoming excessively elongated during sewing, which would give rise to a seam which was longer than required and consequently of unpleasing appearance, as well as being inconvenient for the person putting on the article. Thus the insertion of the terminal edge into the guillotine of the sewing machine is greatly simplified and can be easily mechanized. This is because, since the final area of the article (now consisting of the elastic strip instead of the terminal edge of the fabric forming the finished article) is not torn and is not folded in a random way, it can easily be engaged by mechanical means which insert it into the sewing machine. Essentially, the elastic strip forms a portion of fabric having a greater density and thickness than the soft thin knitted fabric which forms the tubular article. This strip is formed by a selection of needles and consequently with a number of stitches per row which is smaller than those of the rows which form the article. Additionally, at least one of the threads used for this strip is elastic. This causes the article to have a correct extension at rest in the area in which the sewing is to be carried out to close the toe. When the sewing of the terminal edge has been completed, or during the sewing stage itself, the elastic strip is eliminated by a similar process to that used for the terminal part of the fabric. As a general principle, the sewing of the terminal edge of the article may be carried out separately (in both time and space) from the knitting of the article. For example, the individual open tubular articles, when released from the circular knitting machine, can be collected in carriages or other containers and then transported to a department where the sewing takes place; or they may be transported by continuous pneumatic or mechanical transport systems. Here the sewing machines can still be either operator-controlled or automated. In the first case, the presence of the elastic strip simplifies the work of the operator and therefore reduces the time required for insertion of the article into the sewing machine. In the second case, the elastic strip permits simple and reliable handling by mechanical manipulators which grip the individual articles and insert them into the sewing machine. In both cases, it is possible to arrange for a reference mark or a pair of reference marks to be formed in the elastic strip for the correct orientation of the article during its insertion into the sewing machine. The mark can be identified by the operator or read by a sensor associated with the mechanical manipulators. It can be formed, for example, by using a thread of suitable colour. Unexpectedly, it has now been discovered that the use of this new method having the function of simplifying the insertion of the terminal flap or edge of the article into the sewing machine provides further advantages and makes it possible to develop a particularly efficient method and device for automatically sewing the toes of tubular articles immediately after they have been knitted. This is because the elastic strip formed beyond the terminal edge of the tubular article can be used as a means of engaging the article with a transfer member, particularly a tubular member, which picks up the tubular article from the circular needle bed and transfers it to the sewing machine. Thus it becomes unnecessary to provide a relatively complex operation of mechanical engagement of the tubular article on completion of the knitting, before the article is fully released from the knitting needles. In practice, according to an improvement of the present invention, there is provided a method in which, at the end of the knitting of the tubular article and the elastic strip, the tubular article is fully released from the needles of the circular needle bed and engaged, by means of the elastic strip, with a transfer member for transferring the completed tubular article out of the circular needle bed. Thus the transfer of the article does not require the use of mechanical pick-up members which may damage the fabric and which are particularly complex. This is because the article is picked up simply by positioning the transfer member, which in practice may be a simple tube, with its upper edge at a suitable height, typically a few millimetres above the height of what is called the stitch forming plane, in other words the plane on which the needles and sinkers of the circular machine form the knitted fabric. When the fabric is released from the needles, the elastic strip tightens on to the tubular transfer member and on its exterior, thus retaining the tubular article on this member in a predetermined angular position so that the article can be transferred to the sewing machine. Consequently, in a possible embodiment of the present invention, it is possible to provide a method for use in circular knitting machines for producing garments of the stocking type, to enable a garment, on completion of its fabrication process, to leave the machine which has produced it with the toe already closed by sewing by means of an ordinary sewing machine, to which the garment is transferred automatically, without the necessity for manual intervention by an operator and without interruption of the knitting operations. In a practical embodiment, the method comprises the stages of inserting the transfer member coaxially into the circular needle bed at least up to the height of a stitch forming plane; while the transfer member is inserted into the circular needle bed, sucking the tubular article being formed into the transfer member; on completion of the formation of the elastic strip, releasing the tubular article from the circular needle bed in such a way that the elastic strip formed on the terminal edge of the tubular article is engaged elastically on the outside of the transfer member; and extracting the transfer member from the vacated circular needle bed. To obtain correct tensioning of the tubular article during its knitting and to insert the tubular article into the tubular transfer member, the following stages can be provided: providing a suction tube inside the circular needle bed, the suction tube having a laterally openable portion below the circular needle bed; generating a suction inside the suction tube and starting the formation of the tubular article while sucking the fabric being formed into the suction tube; in an intermediate stage of the formation of said tubular article (for example during the formation of the heel), interrupting the suction and opening the lower portion of the suction tube to insert the transfer member into the suction tube; generating a suction inside the transfer member; raising the transfer member coaxially with the suction tube at least up to the height of the stitch forming plane, sucking the tubular article being formed into it; then engaging the tubular article, by means of said elastic strip, with the transfer member, releasing it from the needles, and extracting the tubular article by means of the transfer member. To obtain a seam on the inner surface of the tubular article, the following further stages may be provided: transferring the transfer member, with the tubular article engaged on it, to the sewing machine which may be located under the circular needle bed or preferably at the side of the circular machine; engaging the tubular article at the position of the elastic strip; turning the tubular article inside out, making it slide on the outer surface of the tubular transfer member, until the elastic strip and the terminal edge of the tubular article are brought below the lower end of the transfer member. In this position, the terminal edge is inserted into the sewing machine and more precisely into the guillotine of said machine. In practice, to facilitate the sewing operations, the following stages can be provided: engaging the tubular article at two diametrically opposite points along the terminal edge at the position of the elastic strip to cause it to be turned inside out; after the tubular article has been turned inside out, tensioning the terminal edge and the elastic strip, thus moving said two diametrically opposite points away from each other and bringing next to each other the portions of the terminal edge and of the elastic strip extending between said two points; inserting the terminal edge into the guillotine of the sewing machine; sewing the terminal edge, forming a closed toe, and removing the elastic strip. Advantageously, the tubular article, when turned inside out, can be made to continue to have at least its starting edge engaged with the outer surface of the transfer member; and, after the sewing of the toe of the article, the article can be turned inside out for a second time, being sucked from above into the tubular transfer member, with the assistance, if necessary, of external mechanical members, such as shaped wheels. Thus a second turning inside out is achieved and the article is turned the right way round with the seam inside it. The present invention also relates to a device for producing tubular knitted articles with toes, comprising a circular needle bed on which a tubular knitted article is formed and a transfer member which is brought inside the circular needle bed to remove the tubular article from the circular needle bed on completion of the knitting. Characteristically, according to the invention, the needle bed is programmed to form, on completion of the knitting of the tubular article, an elastic strip associated with the terminal edge of the tubular article, said elastic strip being engaged with the transfer member to retain the tubular article on it when the article is fully released from the needles. According to a practical embodiment, the device according to the invention comprises a suction tube coaxial with and inside the circular needle bed, into which the tubular transfer member is inserted. In practice, to enable the transfer member to be inserted into the suction tube and to provide the suction of the article being formed at the stages when this is necessary, the following arrangements are made in a possible embodiment of the device: the suction tube coaxial with the circular needle bed has an upper portion and a lower portion; the lower portion is openable laterally and is connectable below to a source of suction; the transfer member is inserted into the suction tube through the lower portion of the tube. The suction can be provided by means of a suction outlet which can advantageously be movable coaxially with the circular needle bed to follow the movement of the transfer member when this is inserted coaxially into said suction tube. If the toe is sewn outside and to the side of the circular machine where the circular needle bed is located, then, according to a possible embodiment of the present invention, it is possible to provide a movable carriage which can be moved from a position in the vicinity of the circular needle bed to a sewing station, said movable carriage transferring the transfer member from the circular needle bed to said sewing station and vice versa. A transfer member raising and lowering system can be provided on the carriage to raise and lower said transfer member both when it is at the sewing station and when it is in a position coaxial with the circular needle bed. Further possible advantageous characteristics and embodiments of the device according to the invention are described below with reference to an example of embodiment. Brief description of the drawings The invention will be more clearly understood from the description of an embodiment of it which is provided by way of example and without restrictive intent, with reference to the attached drawings. The following are shown in the drawings: Figs. 1 to 5 show longitudinal sections through the circular needle bed, the suction tube and the transfer member at various stages of the knitting of a tubular article; Figs. 6 to 8 are perspective views of the circular knitting machine and the attached sewing station in various positions of the operating members; Figs. 9 to 24 are partial perspective views of the machine as a whole at various stages of operation; Fig. 25 shows a diagram of the fabric forming the elastic strip adjacent to the terminal edge of the tubular article; Figs. 26 to 33 show, at a succession of stages of operation, a device according to the invention in a different embodiment; and Figs. 34 and 35 show modifications of the device of Figs. 26 to 33. Detailed description of the preferred embodiments of the invention With reference to Figs. 1 to 8 in particular, a description will initially be given of the principal members of the assembly which consists of: the circular knitting machine with the circular needle bed; the sewing station; the transfer member; and the accessory parts provided for the transfer, sewing and release of the tubular article. The circular knitting machine is indicated in a general way by the number 1. Its structure may be similar to that of known circular machines and will therefore be described only in relation to the parts necessary for the understanding of the present invention. The number 3 indicates the circular bed of needles, the latter being indicated by the number 5. The needles are slidable in channels formed in the cylinder 6 of the machine. This cylinder is supported by a bearing 8 and is integral with a toothed wheel 7 which receives the motion from a suitable transmission, not shown, driven by the main motor of the machine, to cause the circular bed 3 of needles 5 to rotate. The needles 5 are fed with threads through thread guide plates 9, and a dial 11 carrying needles interacting with the circular needle bed 3 for forming the knitted fabric is located above the circular needle bed 3. The letter P indicates in a general way a geometrical stitch formation plane, in other words the plane in which the stitches formed by the needles 5 are released. For the sake of simplicity in the drawing, the textile machinery members for controlling the needles 5 are omitted; these members are of known types. A fixed suction tube 13, which, as shown in the perspective view in Figs. 6 to 8, is made in two portions, is positioned inside the circular needle bed 3 and coaxially with it. The upper portion 13A extends into the cylinder 6 of the needles 5, coaxially with the circular needle bed 3. The lower portion 13B is made in two parts separated along a plane containing the axis of the suction tube 13. In Figs. 6 to 8, for the sake of clarity, only the needles 5 and the suction tube 13 of the circular machine 1 are shown. The lower end of the suction tube 13 is connected to a suction outlet 15 forming the terminal part of a flexible suction duct 17 connected to a suction device (not shown). When the two parts forming the lower portion 13B of the suction tube 13 are joined together, as shown in Fig. 6, the suction through the flexible suction duct 17 is propagated into the suction tube 13 up to the stitch forming plane P. Consequently, the tubular article M being knitted is sucked into the suction tube 15, as shown in particular in Figs. 1 and 5. In Figs. 1 and 5, the reference B1 indicates the starting edge, normally elastic, from which the knitting of the article M starts and which, in the finished article, forms the opening of the garment. The knitting proceeds from this starting edge B1 to a terminal edge B2 (see also the following figures), beyond which an elastic strip F1 is then formed for the purposes explained above. The elastic strip F1 is designed to be removed after or during the sewing which closes the terminal edge B2 to form the closed toe of the finished article. A tubular transfer member 21, which is used to pick up the article M on completion of knitting, to transfer it to the sewing machine for closing the toe, is inserted into the suction tube 13, in the way which is described below. Figs. 1 to 5 show the successive stages of operation of the knitting of the tubular article M. More particularly, in Fig. 1 the article M has been virtually completed. As shown schematically in the upper part of the figure, the article M has been provided in its upper part with an elastic strip F1, whose textile structure will be described subsequently with reference to Fig. 25. The lower part of Fig. 1 shows the upper end of the tubular transfer member 21, which has been aligned axially with the suction tube 13 and with the circular needle bed 3. A vacuum is generated inside the tubular transfer member 21, by connecting (in the way which will be described subsequently) the lower end of the transfer member to the outlet 15. Thus, when the tubular transfer member 21 is raised as shown by the arrow f21 (Fig. 1) towards the stitch forming plane P, the article M is sucked into the tubular transfer member 21. In fact, the transfer member 21 can be raised towards the plane P even before the elastic strip F1 has been formed. As it rises upwards, the transfer member 21, owing to the suction through it, draws into itself the whole of the fabric of the tubular article M which has been formed by the needles 5 up to this point, as shown in Fig. 2. The upward travel of the transfer member 21 continues until its upper edge is brought slightly above the stitch forming plane P (Fig. 3), raising the dial 11 if necessary. At this point, the tubular article M which has been completed and provided with the elastic strip F1 is entirely released from the needles 5. The elastic strip F1, having been freed from the needles, tightens around the outer surface of the tubular transfer member 21, as shown in Fig. 4. To maintain the correct angular position of the tubular article M with respect to the transfer member 21, during the last part of the rotation of the circular needle bed the transfer member 21 may be made to rotate together with the needle bed, in other words to follow its rotary movement. This enables the tubular article M to be placed in a precise angular position on the transfer member 21. On completion of the operation of releasing the tubular article M from the needles 5, the transfer member 21 can be moved back downwards, leaving the space for the start of the formation of a new tubular article, as shown in the configuration in Fig. 5, where the new article is indicated by M2. In this way, the stage of extraction of the article M partially overlaps the stage of knitting the next article M2, thus reducing the time required for the knitting and removal of each tubular article from the circular needle bed. As may be noted from the foregoing description, when an elastic strip F1 is formed by means of the circular needle bed 3 on the terminal edge of the article M, the tubular article can be picked up and transferred out of the circular machine 1 without the need for complex mechanical devices for gripping and clamping the fabric which would entail the risk of damaging the fabric. The elastic strip F1 enables the formed tubular article to be entirely released and then to be engaged with the transfer member by means of the elastic force of the elastic strip F1. When the configuration of Fig. 5 has been reached, the transfer member 21 is used to carry the tubular article M out of the circular machine 1 to a sewing station where the article M is turned inside out, sewn along the elastic strip F1 which is removed during or after sewing, and then turned the right way round. The members used to transfer the article M towards the sewing machine and for the operations of turning the article inside out, sewing it and turning it inside out again (in other words, turning it the right way round) will be described with reference to Figs. 6 to 24. The operating cycle relating to the sewing of the toe of the article will then be described in detail with reference to the same figures. On a fixed supporting structure 31 there is placed a horizontal guide 33, along which there runs a carriage 35, movable from a position adjacent to the circular machine 1 (Figs. 8-10) to a position remote from it, at a sewing station indicated in a general way by 37 (Figs. 6-7). A further vertical guide 39, along which a slide 41 runs, is placed inside the carriage 35. The vertical guide 39 and the slide 41 are shown in detail in Figs. 12 to 14, where the outer part of the carriage 35 has been removed for greater clarity in the drawing. The slide 41 carries a jaw 43 which serves to engage with the suction outlet 15. Above the jaw 43 there is a connector 45 for pneumatically connecting the tubular transfer member 21 to the suction outlet 15. The connector 45 is supported in a seat 47 which permits a controlled rotation of the connector 45 and consequently of the tubular transfer member 21 about the axis of the transfer member 21. The rotation is provided by means of an actuator 49. Figs. 6 to 11 show the movement of inserting, raising, lowering and extracting the transfer member 21 with respect to the circular machine 1. More particularly, Fig. 6 shows the stage at which the suction tube 13 is closed, with the two parts 13B delimiting the lower portion of the tube joined together to form a single duct with the upper portion 13A, the duct being pneumatically connected to the flexible suction duct 17 through the suction outlet 15. The tubular transfer member 21 is located at the sewing station 37. When the knitting of the article inside the circular machine 1 has reached a point at which the suction through the suction tube 13 can be interrupted, particularly during the knitting of the heel in the case in which the article M is a sock or a stocking, the two parts 13B forming the lower portion of the suction tube 13 can be opened (Fig. 7) to permit the insertion of the tubular transfer member 21. By a movement of the carriage 35, which moves from the position of Fig. 7 to the position of Fig. 8, the tubular transfer member 21 is brought to a position coaxial with the needle bed 3 of the circular machine 1 and with the suction tube 13. In the last-mentioned position, the jaw 43 engages with the suction outlet 15 and makes it integral with the slide 41 and consequently with the connector 45 and therefore also with the tubular transfer member 21. As described with reference to Figs. 1 to 5, the transfer member 21 has to be raised until its upper end is level with or slightly above the stitch forming plane shown by the line P, while suction is maintained inside said transfer member 21 to introduce the article M being formed into it. This movement is obtained by making the slide 41 run along the vertical guide 39 located on the carriage 33. During this movement, since the suction outlet 15 is engaged by the jaw 43, it remains pneumatically connected to the transfer member 21, the interior of which is therefore in communication with the flexible suction duct 17. The movement of raising the transfer member 21 is shown in Figs. 8, 9 and 10. In Figs. 9 and 10, the transfer member is located in the position of maximum elevation: in position 9, the elastic strip F1 is still joined, along the whole of its circumferential extension, to the needles 5 of the circular bed 3, while in Fig. 10 the fabric has been completely released from the needles and the elastic strip F1 is tightened around the upper part of the transfer member 21 on the outside of this member. Fig. 11 shows an enlargement in the form of a sectional perspective view of the suction tube 13 (or more precisely its upper part 13A) of the transfer member 21, of the circular needle bed 3 and of the tubular article M inserted into the transfer member 21 with the elastic strip F1 tightened around the upper edge of the transfer member 21. As shown in particular in Fig. 11, the transfer member 21 has in its lower part a profile 21A which reproduces the fabric pocket of the toe of the tubular article M, to facilitate the handling of the article during the closing of the toe, as will be explained subsequently. This profile 21 A fills the interior of the fabric in the toe area, where the fabric is more extensive, and this facilitates the operation of inserting the fabric into the guillotine 53 of the sewing machine. When the article M has been entirely released from the needles 5 and then secured to the transfer member 21 by means of the elastic strip F1, the transfer member 21 is again lowered and moved away from the circular machine 1 with an inverse movement of the slide 41 and of the carriage 33. The transfer member again comes to be placed in the position of Fig. 7, but with the tubular article M inserted into it and fixed on it by means of the elastic strip F1. At the sewing station 37, there are various members which are removed in some of the figures for greater clarity of the drawing. Figs. 7 and 8 show in an overall view and Figs. 19 to 23 show in detail views essentially all the members located at this station. The station comprises a sewing machine 51 associated with a guillotine 53 (see Figs. 20 to 22 in particular), into which the fabric of the terminal edge of the article M is inserted, as will be explained subsequently, to carry out the closing of the toe. The guillotine 53 is associated with a bearing strip 55 with which a presser 57 interacts. The presser 57 is driven by actuators 59 carried by a bracket 61 fixed to an arm 62 of the fixed structure 31, to which is also fixed a horizontal guide 63 on which runs a slide 65 which carries the sewing machine 51. The arm 62 carries a second horizontal guide 67, shown in particular in Fig. 22 and omitted for clarity in the other figures, along which a second slide 69 runs. Two grippers 71, which can move towards and away from each other, being driven in this movement by actuators 73 (see again Fig. 22) are mounted on the slide 69. On the structure 31 there is fixed a further vertical guide 81 along which runs a slide 83 which carries a jaw-shaped pick-up member 85 capable of engaging with the upper portion of the tubular transfer member 21 during the sewing of the tubular article M, in the way and for the purposes described below. The inlet of a pneumatic conveyor 87, which is used to suck up and remove the tubular article after the closing of the toe, is placed above the pick-up members 85. A unit 91 carrying a pair of shaped wheels 93, each of which is powered by an actuator 95, is positioned below the pick-up members 85. A cylinder and piston actuator 97 acts on two levers 99 which are angularly fixed to the supports of the wheels 93 and actuators 95 to cause a movement of the two shaped wheels 93 towards and away from each other. The operation of the members described above in the sewing station 37 is as follows and is illustrated in its temporal sequence in Figs. 12 to 24. The tubular transfer member 21 is brought, as mentioned above, into the position shown in Fig. 7, with the tubular article M inside it. The elastic strip F1 is turned over on to the outside of the transfer member 21 and is tightened on it, as shown in Fig. 12. In this position, the tubular member 21 is aligned axially with the inlet of the pneumatic conveyor 87. By a vertical movement of the slide 41 (as shown by the arrow f41 in Fig. 12), the tubular transfer member 21 is raised until its upper end is brought to the height of the grippers 71. These are brought together until they grip the elastic strip F1 turned over on to the outside of the transfer member 21. The grippers 71 grip the elastic strip F1 of the tubular article M at two diametrically opposite points. A movement of the grippers 71 away from each other causes the tensioning of the elastic strip F1, as shown in Fig. 13. In a possible improvement of the invention, the angular orientation of the transfer member 21 and therefore of the tubular article can be made controllable at this stage, so that the article is gripped by means of the grippers 71 in the correct position to obtain the proper orientation of the subsequent seam formed on it. For this purpose, it is possible to arrange for one or more reference marks to be made during the knitting on the edge or preferably on the elastic strip F1, for example by means of a suitably coloured thread. A photocell or other equivalent means, suitably positioned, reads the angular position of the article carried by the tubular transfer member 21 before it is gripped by the grippers 41. The tubular transfer member 21 and the article positioned on it can be rotated by means of the actuator 49 until the desired angular position is reached. When the configuration of Fig. 13 is reached, the slide 41 continues its upward movement, while the elastic strip F1 is held by the grippers 71. Consequently, as shown in Fig. 14, the tubular article M is gradually extracted from the transfer member 21 and turned inside out, sliding along the upper edge of the transfer member 21 and along its outer surface towards the lower edge. The downward sliding of the tubular article M which has been turned inside out is continued by bringing the shaped wheels 93 to bear on the tubular transfer member 21 and making them rotate, to cause, as a result of the friction between the shaped wheels 93 and the fabric forming the article M on the one hand and the slip between said fabric and the outer surface of the transfer member 21 on the other hand, the accumulation of the tubular article M towards the lower area of the transfer member. This configuration is shown in Fig. 15. Thus the upper portion of the tubular transfer member 21 is freed, and this can be gripped by the pick-up member 85 (Fig. 16). The pick-up member 85 is raised by the sliding of the slide 83 along the vertical guide 81 as shown by the arrow f85 (Figs. 17, 18), bringing the upper end of the transfer member towards the inlet of the pneumatic conveyor 87. The shaped wheels 93 push the fabric of the tubular article M further downwards along the outer surface of the transfer member 21. The elastic strip F1 and the edge B2 designed to be sewn to form the closed toe of the article are now located under the lower end of the tubular transfer member 21 and still in a configuration in which they are tensioned by the grippers 21, as shown in Figs. 18 and 19. The article is also tensioned longitudinally by means of the shaped wheels 93 which are made to rotate in the reverse direction. At this point, the slide 65 carrying the sewing machine 51 and the guillotine 53 is moved as shown by the arrow f65 (Figs. 19, 20) in such a way that the tensioned fabric of the tubular article M penetrates into the guillotine. The presence of the elastic strip F1, which has a greater thickness and consistency than the knitted fabric forming the rest of the tubular article, ensures that the terminal area of the article remains well stretched and does not curl up in the area between the two grippers 71. This facilitates the insertion of the fabric into the guillotine 53. The insertion of the fabric into the guillotine 53 and the subsequent sewing are also facilitated by the presence of the profiling 21 A on the transfer member 21, which keeps the fabric forming the toe pocket stretched and tensioned. At this stage, the carriage 33 is removed in a suitable way from the sewing area so that it does not impede the operations of closing the toe of the article. When the fabric has been inserted into the guillotine 53, it is pressed by the presser 57 against the bearing strip 55 in such a way that the grippers 71 can be moved aside (Fig. 21). The sewing machine 51 is then brought under the presser 57 to sew the edge B2, reaching the position shown in Fig. 22. During this movement, the residual textile material consisting of the elastic strip F1 which is eliminated, is cut, in addition to the sewing of the edge B2. The sewing machine 51 then returns to the original position and the presser 57 moves away from the bearing strip 55, thus releasing the sewn terminal edge B2, which now forms the closed toe of the tubular article M (Fig. 23). At the same time, or at a subsequent stage, the upper end of the tubular transfer member 21 is brought to bear on the inlet of the pneumatic conveyor 87 (also shown in Fig. 23). The suction provided by means of the pneumatic conveyor 87 makes the fabric of the article M which is located under the lower edge of the transfer member 21 penetrate into the transfer member. By rotating the shaped wheels 93 again, the article is made to slide downwards so that it is sucked entirely into the tubular transfer member 21, being turned inside out a second time along the lower edge of the transfer member. Fig. 24 shows one instant of this stage of the turning inside out and suction of the tubular article M towards the pneumatic conveyor 87. At the end of this stage, the tubular article M will be discharged at the opposite end of the pneumatic conveyor 87 in a sewn form and turned the right way round, having been turned inside out twice, first along the upper edge and then along the lower edge of the transfer member. At this point, the transfer member can be lowered again, reconnected to the connector 45 located on the slide 41 and brought back to the circular machine 1 to carry out a new operation. As will be seen in the figures described above, with particular reference to the profiling 21A of the transfer member 21, the angular position of the tubular article M can be modified in a controlled way during the transfer from the circular machine 1 to the sewing station 37 by means of the rotation of the connector 45 about its own axis. Fig. 25 shows schematically the fabric of the elastic strip F1. The elastic strip F1 can extend over a small number of rows, for example approximately ten rows of knitting. It is formed by rows consisting of alternating elastic threads FE and double cotton threads FD, knitted as shown in Fig. 25. As can be seen in Fig. 25, each row of stitches is formed with a number of needles equal to half the number of stitches of the last row which forms the tubular article (row R). This is achieved by a 1:1 selection of needles. As a result of this and the presence of an elastic thread, the strip F1 tends to assume a dimension smaller than the dimension of the fabric which forms the remaining part of the article. Figs. 26 to 33 show, in a simplified way and in a succession of stages of operation, a different embodiment of the device according to the invention. Elements identical or corresponding in their function to those of the preceding example of embodiment are indicated by the same reference numbers increased by 200. In these figures, the circular knitting machine is indicated by 201 and the circular needle bed is indicated globally by 203. The number 206 indicates the cylinder in which the channels for the sliding of the needles of the bed 203 are formed. The cylinder 206 is rotated by a belt (not shown) running around a toothed wheel 207 and is supported by supports 208 on a fixed structure (not shown). Within the circular needle bed 203 and the cylinder 206 there is a tube 213 which is integral with the cylinder 206 and rotates with it, and which is supported by bearings 210. The wall of the tube 213 is perforated at least in the portion lying between the bearings 210. This perforated portion of the tube 213 is surrounded by a fixed sleeve 214 which forms an annular suction chamber, connected to a suction duct 216 (see Fig. 27 in particular). The annular suction chamber and the lower end of the tube 213 are closed by a movable shutter 218 (shown in the closed position in Fig. 26 and in the open position in Fig. 27). Thus the suction through the duct 216 produces a vacuum inside the tube 213 when the shutter 218 is in the closed position. Under the cylinder 206 there is a tubular transfer member 221 made in two portions 221A and 221B which are fitted together axially. The lower portion 221 B is connected to a flexible suction duct 217 and is carried by a slide 241 running on a fixed vertical guide 239. A pair of shaped wheels 293 with a horizontal axis, powered by motors which are not shown, interacts with the tubular transfer member 221. It can also be engaged, for the purposes and in the way described below, by a pair of jaws 283 operated by actuators which are not shown. The shaped wheels 293 and the gripping jaws 283 are also shown in the cross sections in Figs. 26A and 27B, taken along the lines A-A in Fig. 26 and B-B in Fig. 27. Two grippers 271 for engaging the elastic strip of the tubular article knitted on the machine 201 are placed above the jaws 283 and are set at an angle of 90° to them. The operating cycle of the machine described up to this point is as follows (see Figs. 26 to 33). The tubular article M is knitted on the needle bed 203, starting from the elastic edge B1 and continuing to the rows which will form the closed toe of the article. While the article is being knitted (Fig. 26), it is sucked into the tube 213 which rotates with the cylinder 206. The suction through the lateral holes in the lower end part of the tube 213 causes the article to accumulate, adhering to the final part of the inner surface of the cylindrical wall of the tube as shown in Fig. 26. This makes it unnecessary to make the tube 213 excessively long, and leaves ample free space below the needle cylinder. During a suitable stage of operation, for example during the knitting of the heel of the article M, the shutter 218 is opened and the tubular transfer member 221 is raised by a vertical movement of the slide 241 along the guide 239 until it enters the tube 213 and reaches the stitch forming plane. When the knitting of the article M is finished and the elastic strip F1 has also been formed on it, the tubular transfer member 221 is raised above the stitch forming plane (Fig. 27) and the fabric can be released from all the needles of the needle bed 203. Thus the article is engaged by means of the elastic strip F1 on the outer surface of the tubular transfer member 221 in the proximity of its upper edge in a similar way to what is shown in Fig. 4 where the tubular transfer member is indicated by 21. A successive descending movement of the slide 241 carries the tubular transfer member 221 out of the needle cylinder 206, until the elastic strip F1 is positioned next to the grippers 271. These grip the elastic strip F1 and put it under tension (Fig. 28). At the same time, since the tubular transfer member has been fully extracted from the tube 213, the shutter 228 can be reclosed. A vacuum is created again above the shutter, making it possible to tension and suck vertically downwards a new article M1 which is beginning to be formed on the circular needle bed 203 (Fig. 28). While the new article M1 is being formed on the circular needle bed 203, the article M is drawn downwards by the grippers 271, which for this purpose are carried by slides or other equivalent members, not shown, which are suitably guided in the vertical travel along the tubular transfer member 221. The grippers 271 are lowered until the elastic strip F1 is brought slightly below the area of joining of the portions 221 A, 221B of the tubular transfer member 221 (Fig. 29). The sliding movement of the article is assisted by the rotation in the appropriate direction of the shaped wheels 293. When this position is reached, the shaped wheels 293 continue to rotate, finishing the extraction of the article M, including its elastic edge B1, from the inside of the tubular transfer member 221 and completing the process of turning the article inside out. The fabric of the article M accumulates between the shaped wheels 293 and the grippers 271 (Fig. 30). When this condition is reached, or even before the article has been turned completely inside out, the lower portion 221 B of the tubular transfer member 221 is axially disengaged from the upper portion 221A by a downward movement of the slide 241, while the upper portion 221A is gripped and retained by the jaws 283 (Fig. 31). The movement of the shaped wheels 293 is reversed to tension the article longitudinally between the wheels and the grippers 271, while the guillotine 253 of a sewing machine (not shown but similar to the machine 51) is brought up to the article (arrow f253, Fig. 32), causing the lower edge of the article, tensioned by the grippers 271, to be introduced into the guillotine, with the elastic strip F1 below the guillotine (Fig. 32). In this way the sewing of the edge forming the closed toe and the removal of elastic strip F1 are carried out. The sewn article is removed by joining a suction duct 287 to the upper end of the portion 221A of the tubular transfer member 221, as shown in Fig. 33. The shaped wheels 293 reverse their direction of rotation, pushing the article towards the lower edge of the portion 221A of the tubular transfer member 221 and enabling it to be turned inside out for a second time inside the tubular member and then to be sucked up from above and removed. The machine can then start a new cycle for the removal, sewing and discharge of the article M1. Fig. 34 shows an alternative embodiment of the final stage of the cycle described above. In this embodiment, the guillotine 253 of the sewing machine is not moved (or is only moved slightly) towards the tubular transfer member 221 and the grippers 271, while the upper portion 221A of the tubular transfer member 221 oscillates (by means of the jaws 283, for example) towards the guillotine. This solution may be suitable when there is insufficient space for bringing the sewing machine to the article. Fig. 35 shows another variant embodiment, in which the guillotine 253 and the tubular article to be sewn are brought together by moving the upper portion 221A of the tubular transfer member 221 towards the guillotine 253 and the sewing machine (not shown) as before, but this time by a traversing movement rather than an oscillatory movement. For this purpose, the jaws 283 and the grippers 271 are mounted on suitable slides (not shown) and the shaped wheels 293 can move apart, for example in the way described above with reference to the preceding example of embodiment. In these examples of embodiment also, the tubular transfer member 221 can have a profiled portion similar to the portion 21A, which in this case will be located in the proximity of the area of the joint between the upper and lower portions 221A and 221 B. It is to be understood that the drawing shows only a practical embodiment of the invention, which can be varied in its forms and arrangements without departure from the basic concept of the invention. The presence of any reference numbers in the attached claims has the purpose of facilitating the reading of the claims in the light of the preceding description and of the attached drawings, and does not in any way limit the scope of protection.

Claims: Method for knitting a tubular knitted article (M) with a starting edge (B1) and a terminal toe, in which the tubular article is knitted on a circular needle bed (3) from the starting edge to a terminal edge (B2) designed to form the toe of the article, characterized in that : an elastic strip (F1) is formed by said needles (5) along the terminal edge; and, on completion of the formation of said elastic strip, the tubular article is released completely from the needles of said circular bed and is engaged by means of the elastic strip with a transfer member (21) for transferring the completed tubular article out of the circular needle bed. Method according to Claim 1, characterized in that said elastic strip is knitted by a selection of the needles of the circular bed, and using at least one elastic thread (FE). Method according to Claim 2, characterized by the following steps: inserting the transfer member (21) coaxially into the circular needle bed (3) at least up to the height of a stitch forming plane defined by said needles (5); while said transfer member is inside the circular needle bed, sucking the tubular article being formed on said needles into said transfer member; on completion of the formation of said elastic strip, releasing the tubular article from the circular needle bed in such a way that the elastic strip (F1) formed on the terminal edge (B2) of the tubular article (M) is engaged elastically with the transfer member; extracting the transfer member, with the article engaged on it, from the circular needle bed. Method according to one or more of Claims 1 to 3, characterized in that said transfer member is a tubular member. Method according to one or more of Claims 1 to 4, characterized in that the knitting of a new tubular article on said circular needle bed is started when said transfer member is removed from the circular needle bed. Method according to one or more of Claims 1 to 5, characterized by the steps of: placing a suction tube (13) inside said circular needle bed (3), said suction tube having an openable portion below the circular needle bed; generating a suction inside said suction tube; starting the formation of said tubular article by said circular needle bed, while the fabric being formed is sucked into said suction tube; in an intermediate stage of the formation of said tubular article, opening said lower portion of the suction tube and inserting said transfer member into the suction tube; generating a suction inside the transfer member; raising said transfer member coaxially with said suction tube at least up to the height of the stitch forming plane, and sucking the tubular article being formed into the transfer member; engaging said tubular article, by means of said elastic strip, with the transfer member; extracting said tubular article from the circular needle bed by means of said transfer member. Method according to Claim 6, characterized in that said transfer member, after it has been inserted up to the stitch forming plane, is raised further with respect to said plane, to bring its upper edge above the stitch forming plane before the tubular article is released from the needles. Method according to one or more of Claims 1 to 7, characterized in that said transfer member, with the tubular article engaged on it, is transferred to a sewing machine (51); the tubular article is engaged at the position of said elastic strip; the tubular article is turned inside out, being made to slide on the outer surface of the tubular transfer member, until said elastic strip and the terminal edge of the tubular article are brought below the lower end of the transfer member. Method according to Claim 8, characterized in that : the tubular article is engaged at two diametrically opposite points along the terminal edge at the position of the elastic strip to cause it to be turned inside out; after the tubular article has been turned inside out, the terminal edge and the elastic strip are tensioned, by moving said two diametrically opposite points away from each other, to bring the portions of the terminal edge and of the elastic strip extending between said two points next to each other; the terminal edge is inserted into said sewing machine; the terminal edge is sewn, forming a closed toe with a seam; the elastic strip is removed. Method according to Claim 9, characterized in that : when it has been turned inside out, the tubular article continues to have at least its starting edge engaged with the outer surface of the transfer member; after the sewing of the toe of the article, the article is turned inside out for a second time, being sucked into the tubular transfer member. Method according to Claim 6, characterized in that the suction tube (13) is integral with the circular needle bed and rotates with it, and in that said tubular article is temporarily made to adhere to the inner surface of said tube by the suction inside said tube. Device for producing tubular knitted articles (M) with terminal toes, comprising a circular needle bed (3) on which a tubular knitted article is formed, and a transfer member (21) which is brought inside the circular needle bed to remove the tubular article from the circular needle bed on completion of the knitting, characterized in that said needle bed is programmed to form, on completion of the knitting of the tubular article, an elastic strip (F1) beyond the terminal edge (B2) of the tubular article, said elastic strip being engaged with the transfer member to retain the tubular article on said transfer member when said article is fully released from the needles (5). Device according to Claim 12, characterized in that said transfer member is tubular. Device according to Claim 12 or 13, characterized in that it comprises a suction tube (13) coaxial with and inside the circular needle bed, said transfer member being inserted coaxially into the suction tube. Device according to Claim 14, characterized in that : said suction tube coaxial with the circular needle bed has a lower openable portion and is connectable below to a source of suction; said transfer member is inserted into said suction tube through the lower portion of the tube. Device according to Claim 15, characterized in that it comprises a suction outlet (15) connectable to said transfer member. Device according to Claim 16, characterized in that said suction outlet (15) is movable coaxially with said circular needle bed to follow the movement of the transfer member when this member is inserted in said circular needle bed. Device according to one or more of Claims 12 to 17, characterized by tensioning members (71) for engaging said tubular article at the position of said elastic strip (F1) and for turning said tubular article inside out, making it slide along the outer surface of the transfer member (21), means being provided to cause a relative movement between said tensioning members and said transfer member in a direction parallel to the axis of said transfer member. Device according to Claim 18, characterized in that said tensioning members comprise two opposing gripping means (71), which grip said tubular article at two approximately diametrically opposite points, said gripping means being movable towards and away from each other. Device according to one or more of Claims 12 to 19, characterized by a jaw (85) for engaging the transfer member. Device according to Claim 20, characterized in that said jaw is vertically movable to move said transfer member towards a pneumatic conveyor (87). Device according to one or more of Claims 12 to 21, characterized by shaped wheels (93) which engage with the outer surface of the transfer member, enabling the tubular article to pass between said outer surface and said shaped wheels. Device according to one or more of Claims 12 to 22, characterized by a sewing machine (51) with a guillotine (53) into which the terminal edge of the tubular article is inserted. Device according to one or more of Claims 12 to 23, characterized by a pneumatic conveyor (87) which is connected to the upper end of the transfer member to cause the suction of the tubular article after the sewing of the toe. Device according to Claim 16 or 17, characterized in that said outlet (15) is connectable alternatively to said transfer member (21) and to said lower portion of the suction tube (13). Device according to one or more of Claims 12 to 25, characterized by a carriage (35) which can be moved from a position in the vicinity of the circular needle bed (3) to a sewing station (31); said movable carriage transferring the transfer member from the circular needle bed to said sewing station and vice versa. Device according to Claim 26, characterized in that said carriage carries a system (39, 41) for raising and lowering the transfer member. Device according to Claim 25 and 26, or 25 and 27, characterized in that said carriage (35) carries an element (43) for engaging the suction outlet, to connect said suction outlet (15) to said transfer member. Device according to Claim 28, characterized in that said carriage carries a tubular connector (45) between said suction outlet (15) and said transfer member (21). Device according to one or more of Claims 14 to 24, characterized in that said suction tube (13) rotates integrally with the circular needle bed (3) and is provided with suction holes in its lower portion, and in that its lower end has closing means. Device according to one or more of Claims 12 to 30, characterized in that said transfer member (221) is made in an upper portion (221A) and a lower portion (221B), which can be joined and separated axially. Device according to Claim 31, characterized in that it comprises a system (283) for moving the upper portion from a position of axial alignment with said circular needle bed to a position in which it is adjacent to a sewing machine (253). Device according to Claim 32, characterized in that said movement system causes a traversing or oscillation of the upper portion of the transfer member. Device according to one or more of Claims 12 to 33, characterized in that it comprises means for reading the angular position of the transfer member and an actuator (49) for the angular positioning of said transfer member.

Inventors: CONTI PAOLO, CONTI, PAOLO
Applicants: GOLDEN LADY SPA, GOLDEN LADY S.P.A.
Application year: 2000
Main classification: D04B9
IPC codes: D04B9