EP3953513B1

EP3953513B1 - Method and apparatus for producing tubular knitted articles with a closed toe

Info

Publication number: EP3953513B1
Application number: EP20719717.9A
Authority: EP
Inventors: Gianni Conti; Massimo VENNI
Original assignee: Loop Srl
Current assignee: Loop Srl
Priority date: 2019-04-11
Filing date: 2020-03-20
Publication date: 2023-08-23
Anticipated expiration: 2040-03-20
Also published as: TWI865503B; CN113825868B; CN113825868A; WO2020208447A1; TW202041736A; IT201900005636A1; EP3953513C0; EP3953513A1

Description

Technical field

The present invention relates to a method for producing tubular knitted articles with a closed toe, in particular stockings and socks.
The invention also relates to an apparatus that implements this method.

Background art

Various methods and apparatus for producing tubular knitted articles with a closed toe are known, disclosed for example in WO2004035894 , WO2010086708 , WO2014167047 , WO2017/067801 , WO2014167047 , EP0592376 , WO2007135697 , WO2018011076 .
In some of these prior art solutions, there is provided a pick-up device of the textile article that, after knitting of the tubular article on the needle cylinder of a circular knitting machine has been completed, picks up the article with the toe still open and transfers it to a sewing/linking machine where sewing or linking of the toe is performed automatically, to finally obtain a tubular article with a closed toe. In WO2017/067801 the pick-up hooks can have a pivoting movement towards or away from the axis of the pick-up device and a latch can slide to close the hook but not when the pick-up hooks are pivoted. EP0592376 discloses a pick-up device with a hook and a slidable latch to maintain the loop in the hook during an overturning step.
In WO2004035894 there is arranged coaxially to the needle cylinder a pick-up member of the tubular knitted article, provided with axial pick-up elements or tubes that are aligned with the needles of the cylinder. In this way, each needle loop of the last course is transferred onto a respective pick-up element.
The loops are then retained on the pick-up elements by respective latches, so as to be unloaded onto the pick-up member releasing the needle cylinder from the tubular article. The pick-up member is divided into two halves, one of which can carry out a rotation through 180° with respect to the other, aligning the respective tubes with one another, and consequently moving the respective needle loops of the last course of the tubular article toward each other. In this way, it is possible to close the toe of the tubular knitted article outside the circular machine, by means of an external sewing or linking machine, which links or sews the needle loops of the two halves engaged on the tubes. By opening the two halves, the tubular article can be unloaded with the toe closed. A drawback of this method is that of a complex and lengthy linking process and the need to produce a high precision pick-up member, which must be able to engage each needle loop of the last course.
In WO2010086708 the pick-up member is provided with a plurality of fixed pick-up hooks that penetrate the needle loops of the last course of the tubular article, allowing the loops to be unloaded from the needles of the cylinder, retaining the article at the open toe. The pick-up member then transfers the tubular article to an external sewing or linking machine that closes the toe. Also in this case, there is the drawback of complex linking and of the need for high precision of the pick-up member.
In WO2014167047 the pick-up member has a plurality of angularly movable pick-up hooks, arranged according to a circular ring divided into two circular half-rings of hooks, which can be overturned one onto the other. The hooks are configured to engage the tubular knitted article, still loaded on the needles of the circular machine, penetrating between the needles, by means of a rotation movement, so as to pick up the sinker loop present between two adjacent needles and avoid picking up the needle loop. The pick-up member can also comprise angularly fixed latches that close the hooks, after the hooks have engaged the respective sinker loops. After the latches have been closed, the needle loops are unloaded from the needles so that the pick-up member can move releasing the needle cylinder from the tubular article. Subsequently, the two circular half-rings of hooks of the pick-up member are overturned, superimposing two opposite edges of the toe of the tubular article, and allowing a sewing machine to close the toe joining the two edges to each other. This system is much faster and less complex than those mentioned above. However, it still does not allow high quality sewing of the toe to be achieved.
Therefore, there is a need to further improve pick-up devices of the tubular knitted articles to increase the quality of the end product while maintaining simplicity of construction.

Summary

Therefore, an object of the invention is to provide a method for producing tubular knitted articles with a closed toe that completely or partly overcomes the drawbacks of the methods of the state of the art. In particular, an object of embodiments disclosed herein is to provide a method capable of reaching maximum precision in the step of sewing/linking the toe, maintaining a simple mechanical structure.
It is also an object of the present invention to provide an apparatus that implements this method.
An object of some embodiments disclosed herein is to provide an apparatus of this type that is less complex than similar apparatus existing on the market.
An object of further embodiments is to provide an apparatus of this type that requires minimum maintenance and provides maximum reliability with respect to existing apparatus.
An object of some embodiments is also to provide a method and related apparatus for producing tubular knitted articles with a closed toe, in which fine gauge linking or sewing of the toe can be implemented.
An object of the invention is to provide an apparatus for picking up tubular knitted articles produced by a circular knitting machine and taking them to a sewing station, implementing this method.
According to the invention, there is provided a method according to claim 1.
With the method described above, it is possible to move each latch portion integrally with the hook portion of the pick-up hook, for example with a rotary or pivoting motion. This makes it possible to maintain control of the loops of the tubular article and, simultaneously, to tension the yarn of which the tubular knitted article is made during some steps of the production process. In particular, it is possible to tension the end loops of the edges of the toe radially outward during the step of sewing or linking. The loops engaged by the hook portions of each pick-up hook remain firmly engaged due to the fact that the heads of the latch portions pivot and rotate together with the hook portions. As will be described below with reference to specific exemplary embodiments, in this way it is possible to obtain a higher quality of the toe sewing.
In the context of the present description and of the appended claims, reference will be made in general to toe closing operations. In general, the toe of the knitted article can be closed by means of linking or sewing. The technique with which the closing operation is carried out is not binding.
In particularly advantageous embodiments, the step of moving each pick-up hook toward the tubular article comprises the step of inserting each pick-up hook between two consecutive needles of the needle bed, to engage a portion di fabric between consecutive needles. In practical embodiments, each pick-up hook engages in this way a sinker loop, i.e., a loop that has been formed by a sinker arranged between consecutive, i.e., adjacent, needles. Therefore, not only the advantages according to the invention are achieved, but also advantages linked to prior art methods, in which the tubular article is picked up at the sinker loops, i.e., between consecutive needles of the circular knitting machine, rather than at the needle loops.
Preferably, the step of rotating each pick-up hook with respect to the pick-up member can comprise the step of rotating each pick-up hook about a rotation axis oriented at 90° with respect to the axis of the pick-up member. This allows the pick-up hook to move radially toward or away from the axis of the pick-up member, respectively in the step of picking up the loop and in the step of tensioning the loop to facilitate sewing/linking.
As mentioned, due to the fact that each latch portion is rotationally constrained to the hook portion, i.e., rotates or pivots integrally therewith, it is possible to rotate the hook portion integrally with the head of the latch portion during the step of closing the toe, i.e., the step of joining the two opposite edges of the toe. The movement is advantageously a radial movement toward the outside, with respect to the axis of the pick-up member. In this way, loop portions forming the opposite edges of the toe to be closed are tensioned radially toward the outside, facilitating sewing or linking and increasing the quality of the end result. In particular, during sewing or linking, by tensioning the last courses of the toe of the tubular knitted article radially toward the outside, it is possible for the sewing or linking yarn to engage a smaller number of courses, for example only the last course. In this way, a thinner seam and, ultimately, an article of better quality, is obtained.
According to the invention, there is also provided a device according to claim 6.
According to the invention, each pick-up hook comprises a latch portion having a stem sliding along the longitudinal axis of the pick-up hook and a head coacting with the hook portion. Moreover, a control device is provided to slide each latch portion along the shank of the respective pick-up hook between a first position, in which the head holds the hook portion open, and a second position, in which the head closes the hook portion to retain the tubular knitted article.
In this way, each latch portion is constrained to the shank and to the hook portion of the pick-up hook so as to participate integrally with the movement in radial direction of the hook portion toward and away from the axis of the pick-up member. At the same time, the latch portion is movable with respect to the hook portion with a movement substantially parallel to the longitudinal axis of the shank of the pick-up hook, so as to be able to move, alternatively, to an open and closed position. In the first open position, the head of the latch portion leaves the hook portion free so that it can engage the tubular knitted article with a radial movement toward the axis of the pick-up member. In the second closed position, the head of the latch portion closes the hook portion, so that the portion of yarn engaged by the hook portion remains constrained thereto, even if the pick-up hook moves radially away from the axis of the pick-up member, for example to tension the loops of the tubular knitted article radially toward the outside.
Each pick-up hook is provided, with respect to the pick-up member, with a radial translation movement. The movement of the pick-up hook, and more in particular of the hook portion, radially toward and away from the axis of the pick-up member is a rotation movement such as to move the hook portion radially toward and away from the axis of the pick-up member, the latch portion moving integrally with the pick-up hook in said rotation movement. The rotation can take place about an axis substantially oriented at 90° with respect to the axis of the pick-up member, around which the pick-up hooks are arranged.
In possible embodiments, the shank of each pick-up hook can have a laminar shape and can have at least one protrusion or one slot, while the stem of the latch portion can have at least one slot in which the protrusion of the shank engages by sliding, or one protrusion that engages in the slot of the shank. With this embodiment, pick-up hooks of limited thickness, and hence adapted to coact with cylinders with very fine needles, are obtained.
In other embodiments, the shank of each pick-up hook can be box-shaped and comprise an internal sliding seat, in which the stem of the corresponding latch portion is housed. In this way, a sturdier structure and better guiding of the latch portion with respect to the shank of the pick-up hook are obtained.
To obtain easier coupling of the pick-up hook to the circular ring, and hence ultimately to the pick-up member, in particularly advantageous embodiments, the shank of each pick-up hook can have a fixing or anchoring portion, to movably constrain the pick-up hook to the pick-up member. The fixing portion can comprise two mutually complementary elements, which form a coupling seat, for example approximately circular in shape. The two elements can be elastically deformable to open and close the seat. To this end, at least one of the two elements, or both these elements, can be produced by means of a portion of elastically flexible plate. The portion of elastically flexible plate can be obtained by means of cutting or shearing from a sheet that forms the shank of the respective pick-up hook.
According to a further aspect, there is described herein a system for producing tubular knitted articles, comprising in combination:

a circular knitting machine with a needle cylinder comprising a circular needle bed;
a pick-up device as defined above;
a machine provided with sewing or linking needles, to close two opposite loop edges of a toe of the tubular article.

According to particularly advantageous embodiments, the pick-up hooks are configured and arranged to each be inserted between two adjacent needles of the circular needle bed and in this way engage the sinker loops of the tubular knitted article produced by the circular needle bed of the knitting machine.
The method has the feature that the pick-up hooks comprise a shank, having a longitudinal axis, terminating with a hook portion and fixed to the pick-up member by means of a fixing portion, and comprise a latch portion having a stem sliding on the hook portion along the longitudinal axis. Preferably, the latch portion has a head located on a same side of the hook portion and a tail on the part opposite the head.
Moreover, it has the feature that the step of engaging the tubular knitted article by means of the plurality of pick-up hooks comprises:

arranging each pick-up hook in a first position, spaced from the tubular knitted article, in said first position the head of the latch portion holding the hook portion open;
moving each pick-up hook, integrally with the latch portion, from the first position toward the tubular knitted article to a second position, in which the hook portion of each pick-up hook engages the tubular knitted article and,
sliding the stem of each latch portion of each pick-up hook along the longitudinal axis of the shank until closing the hook portion, thus preventing the tubular knitted article from being released from the pick-up hooks.

Finally, the method has the feature that the step of joining includes a step of elongating the loop portions by means of rotation of the pick-up hooks integrally with the latch portions.
This method solves the problem, which occurs in the step of closing the toe, of uncertainty of engagement of the sewing needles. In fact, the integral rotation of pick-up hook and latch widens the loop and allows the sewing needles plenty of space for engagement. This solution was not possible in the prior art, where the latch slides on the pick-up member and not on the pick-up hook, and hence cannot rotate together with the pick-up hook, making the pick-up hook unable to carry out any movement to widen the loop.
Preferably, the step of moving the pick-up member toward the tubular knitted article until the hook portion of each of the pick-up hooks couples the tubular knitted article includes a step of rotating the pick-up hooks integrally with the latch portion into the first position.
In a possible embodiment of the method, a pick-up hook is provided angularly on the pick-up member every two needles of the circular machine, and the pick-up hooks have a front section with cross dimensions greater than the distance between adjacent needles. The pick-up hooks penetrate between pairs of alternate needles, increasing the distance between pairs of needles between which the pick-up hooks penetrate and reducing the distance between pairs of needles between which the pick-up hooks do not penetrate. In this way the step of closing the toe is implemented with fine gauge sewing/linking and with double pitch.
According to another aspect of the invention, there is provided a system according to claim 11.
A system of this type makes it possible to provide the method indicated above, achieving the aforesaid objects.

Brief description of the drawings

Further features and/or advantages of the present invention will be more apparent from the description below of an embodiment thereof, provided by way of non-limiting example, with reference to the accompanying drawings, wherein:

Fig. 1 shows a sectional view according to a vertical plane of a circular knitting machine in a step of completing knitting of a tubular knitted article;
Fig. 1A shows an enlargement of a portion of Fig. 1 illustrating needles, yarn guides with associated yarn, a tubular knitted article, sinkers, a final end edge of the tubular knitted article;
Fig. 1B shows the last courses after the step of knitting has been completed;
Fig. 2 and Fig. 3 show, in a vertical section, the circular knitting machine during steps of lifting of the dial and of the yarn guides from the circular needle bed to leave space for a pick-up member;
Figs. 4 and 5 schematically show the sequence of arrival and arrangement of a pick-up member of the tubular knitted article coaxially to the needle cylinder and over the needle bed;
Fig. 5A shows an enlargement of a portion of Fig. 5 in which a pick-up hook in open configuration is visible;
Figs. 5B and 5C show an enlargement of a practical implementation of the constraint between pick-up hook and pick-up member;
Figs. 6-6D schematically show a possible embodiment of a pick-up hook according to the invention, as in Fig. 5A, respectively in side elevation and open position (Fig. 6), in plan view according to the arrows VIA (Fig. 6A), in side elevation and closed position (Fig. 6B), in its components (Fig. 6C, 6D);
Fig. 7 schematically shows a step of positioning the pick-up member coaxially to the needle cylinder and in a position of engaging with pick-up hooks at the height of the loop;
Fig. 7A shows an enlargement of a portion of Fig. 7 illustrating a pick-up hook arranged close to the knitting members in an open configuration;
Fig. 8 schematically shows the step of picking up after rotation of the pick-up hooks about the respective rotation axes;
Fig. 8A shows an enlargement of a portion of Fig. 8;
Figs. 8B and 8C show, respectively in a sectional and plan view, the position of the pick-up hooks before the step of penetration into the courses of the tubular knitted article;
Fig. 8D shows the step of rotating the pick-up hooks about the respective rotation axis to engage the course;
Fig. 9 shows a step of unloading the loops from the needles after closing the pick-up hooks;
Fig. 9A shows an enlargement of a portion of Fig. 9, with closing of the latch of the hooks;
Figs. 9B and 9C show, respectively in succession, lifting of the needles and the step of unloading the tubular knitted article from the needle cylinder through lowering of the needles;
Fig. 10 schematically shows the step of lifting the tubular knitted article by means of the pick-up member;
Figs. 11 and 11A show, in a front view and a plan view, the rotation movement of the pick-up member about its rotation axis to carry out removal of the tubular knitted article by means of pick-up hooks and positioning in a toe sewing station;
Fig. 12 schematically shows the step of inverting the tubular knitted article by means of a suction duct in the toe sewing station;
Fig. 13 schematically shows the step of overturning one of the half-rings of pick-up hooks so as to superimpose the two opposite edges of the toe of the tubular knitted article on each other;
Figs. 14, 14A, 14B, 14C show, respectively, a sectional view of the apparatus in the toe closing station, a partial plan view and two enlargements of the pick-up member, in the step of joining the opposite edges of the tubular knitted article by means of linking or sewing;
Fig. 14D shows a sectional view of the step of closing the toe with elongation of the loops by the hooks;
Fig. 15 shows a step of completing sewing and disengaging the head of the pick-up hooks from the course;
Fig. 15A shows an enlargement of a portion of Fig. 15 which better illustrates opening of the latch of a half-ring to release the loop;
Figs. 16 shows a step of counter-overturning the half-ring of pick-up hooks and unloading of the tubular knitted article from the pick-up hooks;
Fig. 16A shows an enlargement of a portion of Fig. 16;
Figs. 17, 18, 19 show the sequence relating to unloading and removing the tubular knitted article with closed toe from the pick-up hooks after the step of joining the two opposite edges has been completed;
Figs. 20, 20A, 20B schematically show, in a side elevation view, in a longitudinal section view according to the arrows XXA and in an exploded view, a possible variant of embodiment of a pick-up hook according to the invention;
Figs. 21, 21A, 21B, schematically show, in a side elevation view, in a longitudinal section view according to the arrows XXIA and in an exploded view, another possible variant of a pick-up hook according to the invention;
Figs. 22, 22A schematically show, in a side elevation view and in a cross sectional view according to the arrows XXIIA, a further possible variant of embodiment of a pick-up hook according to the invention;
Figs. 23, 24 show a variant of embodiment of the pick-up hooks described in a step of insertion between the needles;
Figs. 25, 25A, 25B, 25C schematically show, in a side elevation view, in a cut view of the hook portion alone, in a sectional view according to the arrows XXVB and in an exploded view, a possible variant of embodiment of a pick-up hook, according to the variant of Figs. 23 and 24.

Description of some embodiments

Fig. 1 shows, in a partial section on a vertical plane, a system according to an embodiment of the invention, comprising a circular knitting machine 200 in a step of completing knitting of a tubular knitted article 10.
In a known manner, the machine 200 carries out a knitting process of the tubular article 10 starting from the formation of the edge 20, normally using an elastic yarn, and ending with the formation of the last course 30.
In the aims of the present invention, the last course 30, and some of the courses formed immediately before the last course, for example the second last, the third last and the fourth last, form a final end edge 31 of the tubular knitted article 10, which must be sewn or linked to form a closed toe, such as the toe of the foot of a stocking or of a sock.
Just as in the prior art, the circular machine 200 comprises jacks 230, a needle cylinder 220, in which needles 210 of a circular needle bed slidingly engage, control cams 215 and actuators 240 to carry out a reciprocating vertical movement of the needles 210.
Moreover, the circular machine 200 coacts with a dial 250, coaxial to the rotation axis 201 of the needle cylinder 220, and with yarn guides 400, of which one is more visible in Fig. 1A, which feed the needles 210 with yarn 410 to knit the tubular knitted article 10.
Between the needles 210 sinkers 225 are arranged, consisting of a plurality of thin shaped plates destined to coact with the needles 210 in forming the loops of the tubular knitted article 10. Again, as shown in Fig. 1, after circular knitting has been completed, the last course 30 of the tubular knitted article 10 is engaged on the circular needle bed 210 of the needle cylinder 220, while the dial 250 has started to rise with respect to the circular needle bed 210. These devices and their operation are not described in further detail, being know to those skilled in the art.
Fig. 1B, by way of example, represents in a top view a portion of the final end edge 31 of the tubular knitted article 10 after knitting has been completed, in a step in which the needles 210 are still engaged in the last course of loops 30. The loops 30 are called herein needle loops, while adjacent pairs of needle loops 30 are joined by a respective sinker loop, formed by the portion or loop of yarn that joins the needle loops engaged with consecutive needles 210, i.e., adjacent to one another in the circular needle bed.
After knitting of the tubular article 10 has been completed, the yarn guides 400 are raised in the direction indicated by the arrow 401 as shown in Fig. 2 and Fig. 3, which show further raising of the dial 250 in the direction indicated by arrow 251, to create space and allow (see Fig. 4) raising of the tubular knitted article 10 on the needles 210, for example by means of a tube 205 arranged inside the needle cylinder 220 and movable coaxially with respect thereto. In this step, the needle loops 30 remain engaged with the respective needles 210 and are not unloaded. To protect the tubular knitted article 10, preventing it from catching in the knitting members and in particular in the needles 210 and in the sinkers 225, the tube 205 is positioned coaxially to the cylinder 220 and comprises a flared upper edge 206. The tube 205 is then raised, taking its upper edge 206 above the ring di sinkers 225. In order for the tube 205 to be raised beyond the sinkers 225, grooves, not shown, can be provided on the upper edge 206 of the tube 205 for passage on the sinkers 225.
In particular, as shown in Fig. 4, an embodiment of the apparatus according to the invention comprises a pick-up member 300, described in greater detail below. In Fig. 4 the pick-up member 300 is sectioned in a different vertical plane to that of the yarn guides 400. The pick-up member 300 is part of a pick-up device 318 that can rotate in a cantilever fashion about an axis 301 between at least two positions opposite each other, as described below.
As shown in Fig. 5, while the needles 210 of the circular needle bed are still in the raised position to retain, in this position, the tubular knitted article 10, the pick-up member 300 is rotated about the axis 301 and taken to a position coaxial to the needle cylinder 220 and to the tubular knitted article 10. This movement is made possible by means of rotation (arrow 304) of the whole pick-up device 318 about the axis 301 until the pick-up member 300 is taken to a coaxial position over the needle cylinder 220, inside the space left free by the dial 250, previously raised.
In particular, the rotation according to the arrow 304 of the pick-up member 300 about the axis 301 is made possible by drive members 350 which, besides allowing the aforesaid rotation about the axis 301, are also able to cause an axial lifting or lowering of a shaft 354, as described below.
The pick-up member 300 comprises a circular support 310 divided into two half-supports, which form two circular half- rings 310a, 310b of pick-up hooks 100. The two circular half- rings 310a, 310b can be overturned one onto the other about a pivot 305. The two half- rings 310a, 310b, when arranged approximately coplanar to form the circular support, are concentric with respect to an axis 315 of the pick-up member 300. The pivot 305 defines a tipping axis substantially orthogonal to the axis 315 of the pick-up member 300, about which axis the pick-up hooks 100, visible in the enlargement of Fig. 5A, are distributed. Each pick-up hook 100 is constrained, by means of a fixing portion 104, to a corresponding connection member 308 with which each pick-up hook 100 is fixed to the pick-up member 300. The constraint between pick-up hook 100 and pick-up member 300 is such as to allow each pick-up hook 100 to rotate with respect to a rotation axis 302 (see Fig. 8A, in particular) oriented substantially at 90° with respect to the axis 315 of the pick-up member 300. In particular, the rotation axis of the pick-up hook 100 of Fig. 5A is substantially orthogonal to the plane of Fig. 5A. Each pick-up hook 100 has its own horizontal rotation axis 302, different from the axes of the other pick-up hooks 100. Said rotation axes 302 are formed by straight lines tangent to a circumference coaxial to the pick-up member 300.
The constraint between each pick-up hook 100 and the respective circular half- ring 310a, 310b can be obtained in a manner known, from WO2017067801 , for instance. Figs. 5B and 5C show the implementation details of an embodiment. Along the semicircular extension of each half- ring 310a, 310b grooves 311 are provided along radial planes, i.e., planes containing the axis 315 of the pick-up member 300. Each circular half- ring 310a, 310b is provided with a semi-annular recess 312 (Fig. 5B) which extends about the axis 315 of the pick-up member 300. The position of the above-mentioned grooves in relation to the axis 315 are those taken when the circular half- rings 310a, 310b are positioned coplanar (Figs. 4 and 5). Assembly of the pick-up hooks 100 takes place by inserting a wire or coil spring with a circular section (indicated with 308 in Fig. 5C) into the recess 312 and then coupling each pick-up hook 100 with its fixing portions 104 to the wire or coil spring 308.
An embodiment of a pick-up hook 100 according to the invention is illustrated in Figs. 6, 6A, 6B, 6C, 6D. The pick-up hook 100 comprises a shank 101, having a longitudinal axis 102 and terminating with a hook portion 103.
The shank 101 comprises the fixing portion 104, for example by means of snap fitting in the connection portion 308 of the pick-up member 300 of Fig. 5A, i.e., through snap coupling to the wire or spring with circular section housed in the recess 312 (Figs. 5B, 5C). In particular, the fixing portion 104 can be formed by two opposite halves 104a, 104b elastically connected in a cantilever fashion to the shank 101. This facilitates insertion and removal of the pick-up hook 100 on and from the connection portion 308, for example formed by the spring or wire of Fig. 5C, of the pick-up member 300, in the event of maintenance or replacement operations, while at the same time ensuring minimum rotation friction about the connection portion 308.
The pick-up hook 100 further comprises a latch portion 105 having a stem 106 constrained through a prismatic pair, i.e., a sliding pair to the shank 101 so as to be able to slide with respect thereto along the longitudinal axis 102, i.e., parallel to the longitudinal axis 102. The latch portion 105 can have at one end a tail or butt 107 and at the opposite end a head 108 located on the same side as the hook portion 103 and configured to close the hook portion 103 so as to block loop portions on the pick-up hook 100, as described below. In other embodiments, the tail or butt 107 can be arranged in an intermediate position along the longitudinal extension of the stem 106 and have a shape different than the one shown in Figs. 6-6D.
In Figs. 5 and 5A, the latch portion 105 of a pick-up hook 100 is shown in a first position, in which the head 108 is spaced from the hooked end of the hook portion 103 and holds said hook portion 103 open. Moreover, each pick-up hook 100 is in a divergent position, i.e., with the head 108 of the latch portion 105 and with the hook portion 103 spaced radially with respect to the axis 315 of the pick-up member 300. In this way, the pick-up hooks 100 prepare the approach toward the tubular knitted article 10, in the manner shown in Figs. 7 and 7A, where the pick-up member 300, once positioned coaxially to the rotation axis 201 of the needle cylinder 220, moves vertically downward according to the arrow 365 toward the tubular knitted article 10 raised on the needles 210.
In some embodiments, such as the one shown in the enlargement of Fig. 7A, the pick-up member 300 can comprise a tubular element 320, mounted on the circular support 310, to align the loops of the last course of the tubular knitted article 10 on a plane substantially orthogonal to the rotation axis 201 (Fig. 7) of the needle cylinder 220 of the circular machine 200. This makes capture of the tubular knitted article 10 by the pick-up hooks 100 easier.
As shown in Figs. 8, 8A, after the tubular knitted article 10 has been approached, the pick-up hooks 100 are rotated about their respective rotation axes 302 by means of an actuator 331, which is part of a drive assembly 330 and which moves in the direction of the arrow 335.
In particular, the pick-up hooks 100 rotate each about its own rotation axis 302 and move the hook portion 103 (lower end portion) starting from the first position, radially farthest from the axis 315 of the pick-up member (Fig. 8C), toward the rotation axis 201 (Fig. 8D) of the needle cylinder 220 and towards the axis 315 of the pick-up member according to a rotation indicated by the arrow 216 (Fig. 8D), to thus reach a second position, radially closer to the axis 315 of the pick-up member, shown in Fig. 8A, in which each hook portion 103 engages the tubular knitted article 10.
As can be seen in Fig. 8B, the pick-up hooks 100 of the pick-up member 300 are angularly staggered with respect to the needles 210 of the needle cylinder 220. In this way, rotating according to the arrow 216 (Fig. 8D) about the respective rotation axes 302 (Fig. 8A), each pick-up hook 100 is inserted between two adjacent, i.e., consecutive, needles 210 and each hook portion 103 engages the edge 31 (Fig. 8B). In particular, the hook portion 103 engages the loop portion 32 visible in Fig. 8B, i.e., the sinker loop, which is located between two adjacent needles 210. The latch portion 105 is constrained to the remaining part of the pick-up hook 100 so as to rotate integrally therewith about the rotation axis 302. In substance, the two components, which are slidable with respect to each other in the direction of the longitudinal axis 102, are constrained to rotate together with one another about the longitudinal axis 102.
As shown in Figs. 9 and 9A, to block the loop engaged by the hook portion 103 of each pick-up hook 100, the latch portion 105 is pushed by an actuator 340 (Fig. 9A), which is mounted on the pick-up member 300, in the direction indicated by the arrow 336, so that the shank 106 of the latch portion 105 slides parallel to the axis 102 (see also Fig. 6B). In this way, the head 108 of each latch portion 105 closes the hook portion 103, trapping therein the loop portion 32 that was engaged thereby (Fig. 9A). The sliding movement of the latch portion 105 along the axis 102 of the pick-up hook is controlled by the actuator 340 acting on the butt 107.
At this point, starting from the position of Figs. 9 and 9A, as shown in Figs. 9B and 9C, each needle loop (needle stitch) is unloaded by each respective needle 210 that has formed the needle loop. To this end, in a known manner, each needle 210 first travels upward as indicated by the arrow 217 of Fig. 9B, until the needle latch 211 of the needle 210 moves beyond the respective loop of the last course 30, and then travels downward, as indicated by the arrow 218 of Fig. 9C, so that the needle latch 211 pivots upward resting on the hook of the needle 210 and closes it, allowing the needle to be withdrawn downwardly from the last stitch formed. By carrying out this operation for each of the needles 210 the last course of stitches is completely unloaded from the needles 210 and transferred onto the pick-up hooks 100. In this way, the tubular knitted article 10 remains engaged only to the pick-up member 300 by means of each pick-up hook 100.
The aforesaid movements of rotation of the pick-up hooks 100 of Fig. 8D, of closing of the latch 105 of Fig. 9A, and of unloading of the loop or stitch of Figs. 9B and 9C, take place by means of progressive and synchronous indexing rotation of the circular machine 200 about the axis 201 and of the pick-up member 300 about the axis 315 (Fig. 9).
In other embodiments it is also possible for these movements to take place simultaneously.
As shown in Fig. 10, once the tubular knitted article 10 has been engaged by the two half- rings 310a, 310b of pick-up hooks 100, the pick-up member 300 is raised along with tubular knitted article 10 according to the arrow 303 by the drive assembly 350.
Next, as shown in Figs. 11, 11A, the pick-up member 300 rotates in a cantilever fashion about the axis 301 by an angle 304 (for example comprised between 120° and 180°), removing the tubular knitted article 10 from the needle cylinder 220 completely.
In a possible embodiment, a suction duct 360 is arranged over the pick-up member 300, so that, by means of air suction 361, the tubular knitted article 10 is drawn upward (Fig. 12) and everted carrying the elastic edge 20 upward, while at the bottom the end edge 31 is retained by the pick-up hooks 100.
Again with reference to Fig. 12, by advancing an actuator 332 of the drive assembly 330, the pick-up hooks 100 are rotated once again into a spread apart position, carrying out the reverse movement with respect to Fig. 8D, but maintaining the latches 105 (which rotate integrally with the hook portion 103 of each pick-up hook 100) in the closed position of Fig. 9A. Rotation always takes place about the fixing portion 104 and the rotation axes 302 (Fig. 8A), so that the hooked end portion 103 of each pick-up hook 100 moves away from the axis 315 of the pick-up member 300, thus widening the edge 31 to facilitate sewing as described below. The aforesaid rotation movements of the pick-up hooks 100 take place in sequence according to a corresponding indexing movement of the pick-up member 300 about the axis 315.
Next, as shown in Fig. 13, to perform sewing or linking (or more generally closing) of the toe, the half-ring 310a of pick-up hooks 100 is overturned by 180° by means of rotation on the pivot 305, which for example can be a motorized pivot, until it is superimposed on the half-ring 310b. In this way, the half- rings 310a and 310b of pick-up hooks 100 are opposite to one another; the respective loop portions 32, and the edge stitches 31 are maintained elongated by the rotation described above of the pick-up hooks 100, by means of which the hook portions 103 have been moved away in radial direction from the axis of the pick-up member 300.
According to one of the aspects of the invention, following the integral rotation movement into the position spread apart of the pick-up hooks 100 and of the latch portions 105, it is possible to maintain the edge loops or stitches 31 widened and the hook portions closed, so that the loops or stitches remain engaged in the pick-up hooks 100. Providing latch portions 105 that remain integral with the hooks 100, rotating therewith about the rotation axes 302, is therefore particularly advantageous with respect to the prior art. In fact, by rotating the pick-up hooks 100 to elongate the loop portions 32, the quality of the sewing to close the toe of the tubular knitted article 10 is greatly improved, as clarified below. In prior art solutions in which the article is picked up by closing the pick-up hooks with other members, this rotation would not be possible, since the hook portions would lose the loop or stitch.
Closing of the toe is thus possible as shown in Figs. 14, 14A, 14B, 14C, where a closing device 500, for example a linking or sewing device, provided with curved needles 505, is placed adjacent to the two half- rings 310a, 310b of pick-up hooks 100 positioned opposite each other. The curved needles 505 thus perform sewing/linking while the pick-up member 300 carries out synchronous indexing rotations about its axis 315.
In this step the actuators 332 and 333 maintain the spread apart angular position of the pick-up hooks 100 about the rotation axis 302, widening the loop portions 32 retained by the respective half- rings 310a, 310b as much as possible, to obtain complete sewing/linking of the two loop edges to each other along the semi-circumference of the two opposite half- rings 310a, 310b of pick-up hooks 100.
In this step, the pick-up hooks 100 can have been opened in the previous step, before closing of the two opposite half- rings 310a, 310b of pick-up hooks 100, or can be closed after closing of the two half-rings, according to two possible alternative variants of embodiment.
In the second case, by means of the action of the actuators 332 and 333, the pick-up hooks 100 carry out a pivoting opening and closing movement (see Fig. 14D) along a vertical plane, synchronized with a sewing movement of the needles 505, about a rotation axis 506 (Fig. 14B), to allow closing of the toe of the tubular knitted article along the arc defined by the by the half-rings of hooks.
It must be stressed that in both cases there is no risk of the elongated loop escaping from the pick-up hook 100 in the step of sewing/linking the toe, due to closing of each hook portion 103 by the latch portion 105, guaranteed by the fact that during rotation of each pick-up hook 100 about the respective fixing portion 104 and the rotation axis 302, the respective latch portion 105 also rotates about the rotation axis 302 integrally with the respective pick-up hook 100.
After closing, for example by sewing or linking, of the toe of the tubular article 10 has been completed, the two half- rings 310a, 310b are still opposite each other and the tubular knitted article 10 is held upward by means of air suction 361. In order for the tubular article 10 with closed toe to be released from the pick-up member 300 and be able to be drawn upward by suction, the pick-up hooks 100 carry out two consecutive operations to release the loop, described below.
A first operation shown in Figs. 15 and 15A, involves the action of actuators 343 that, by means of a cam 344, push the butts 107 of the pick-up hooks 100 of the single half-ring 310b thus raising the head 108 of the latch 105. Unloading of the tubular knitted article 10 with the closed toe is thus unloaded from the pick-up hooks 100 of the half-ring 310b of pick-up hooks 100. This operation is carried out with a simultaneous indexing movement of the support 310 about the axis 315.
Then, as shown in Fig. 16, the two half- rings 310a, 310b of pick-up hooks 100 return to coplanar position through a reverse rotation, according to the angle 306 of 180°, by rotating the pivot 305. Then, as the half-ring 310b of pick-up hooks 100 has been released from the loops or stitches (Fig. 15A), while the half-ring 310a of pick-up hooks 100 still has the latches 105 in closed position, the closed edge 31 of the tubular knitted article 10 follows the half-ring 310a of pick-up hooks 100.
To release the tubular knitted article 10 from the half-ring 310a of pick-up hooks 100, as shown in Fig. 16A, by means of the cam 344, an actuator 343 selectively pushes the butt 107 of the latches 105 of the single half-ring 310a upward according to the arrow 343, in this way causing raising of the head 108 of the latch 105, obtaining unloading of the tubular knitted article 10 with the closed toe from the pick-up hooks 100 for the half-ring 310a. This operation is also carried out with a simultaneous indexing movement of the support 310 about the axis 315.
The indexing rotation of the pick-up member 300 about the axis 315 is made possible, for example, by the drive members 350 that rotate the shaft 354, neither of which are shown in this figure, about a pivot 355 mounted on which is a toothed pulley 356, adapted to drive a belt 357 connected to the pick-up member 300 (Fig. 16).
Figs. 17-19 show a sequence of possible steps for unloading the tubular knitted article 10 with closed toe obtained by means of lowering of the suction duct 360 which, being positioned coaxially to the tubular knitted article 10 and having a smaller outer diameter, penetrates into it and moves close to the outer surface of the pick-up member 300. Following air suction 361, the sewn toe is first raised, creating a cusp due to the difference in pressure inside and outside the suction duct until the tubular knitted article 10 exiting from the suction duct 360 is completely overturned.
Figs. 20, 20A, 20B illustrate a further embodiment of the pick-up hook 100. In this case, analogously to what was described for the pick-up hook 100 of Figs. 6-6D, it comprises a shank 101, having a longitudinal axis 102 and terminating with a hook portion 103. The shank 101 comprises the fixing portion 104 with which the pick-up hook 100 is fixed to the half- ring 310a, 310b, with the possibility of rotating about the respective rotation axis 302. In particular, the fixing portion 104 can be formed by two opposite halves 104a, 104b elastically connected in a cantilever fashion to the shank 101. The pick-up hook 100 further comprises a latch portion 105 having a stem 106 sliding on the hook portion 103 along the longitudinal axis 102. The latch portion 105 can have a butt 107 at one end and a head 108 at the opposite end, located on the same side as the hook portion 103 and configured to close the hook portion 103 so as to block loop or stitch portions in the pick-up hook 100. In this embodiment, the shank 101 can have a laminar shape with protruding portions 101b, for example produced by means of drawing, configured to slidingly engage slotted portions 106b of the stem 106. Just as in the embodiment described previously, also in this case the connection between the two components of the pick-up hook 100 is such that the latch portion 105 rotates integrally with the shank 101 and the hook portion 103, but is able to slide with respect thereto parallel to the longitudinal axis 102 of the pick-up hook 101.
Figs. 21, 21A, 21B illustrate yet another embodiment of the pick-up hook 100 analogous to the one of Figs. 20-20B. The reference 101c indicates protruding portions configured to slidingly engage slotted portions 106c of the stem 106, produced by means of punching and bending the sheet forming the element 101.
Figs. 22-22A illustrate a further embodiment of pick-up hook 100 in which the shank 101 can be box-shaped and comprises an inner sliding seat 101a for the stem 106 of the latch portion 105. This solution, although less thin than the previous ones, has the advantage of protecting the latch 105 inside the shank 101.
Figs. 23 and 24 show a modified embodiment of the invention, in which the hook portions 103 of the pick-up hooks 100 have a front area, facing the axis 315 of the pick-up member 310. The front area has a tapered shape with a maximum transverse dimension 224 greater than the distance 226 between adjacent needles. The figures show, in particular, two sequences of steps of moving the pick-up hooks 100 toward the needles 210 and of insertion therebetween. In particular, the pick-up hooks 100, penetrating between adjacent pairs of needles 210, reduce the distance 226, in this way making it possible, in the linking or sewing step, to obtain finer gauge sewing and with a double pitch. This variant has the advantage of having less pick-up hooks than needles, and hence greater simplicity of construction.
Figs. 25-25C show an embodiment of a pick-up hook 100 adapted to obtain sewing or linking like the one described in Figs. 23-24. In this case, analogously to what was described for the pick-up hook 100 of Figs. 6-6D, it comprises a shank 101, having a longitudinal axis 102 and terminating with a hook portion 103, wherein the shank 101 comprises the fixing portion 104. In particular, the fixing portion 104 can be formed by two opposite halves 104a, 104b elastically connected in a cantilever fashion to the shank 101. The pick-up hook 100 further comprises a latch portion 105 having a stem 106 sliding on the hook portion 103 along the longitudinal axis 102. The latch portion 105 can have a tail or butt 107 at one end and a head 108 at the other end located on the same side as the hook portion 103 and configured to close the hook portion 103 so as to block loop or stitch portions on the pick-up hook 100. The section of Fig. 25B shows the greater dimension 224 of the pick-up hook 100 and the section with tapered geometry of the hook portion 103 to facilitate entry between the needles 210.
While the invention has been described in terms of various specific embodiments, it will be apparent to those skilled in the art that modifications, changes and omissions are possible without departing from the scope of the claims.

Claims

A method for producing tubular knitted articles (10) on a circular knitting machine (200) comprising a needle cylinder (220) with a circular needle bed (210); wherein the method comprises the following steps:
knitting a tubular knitted article (10) starting from an edge and ending with an open toe;

arranging coaxially to the needle cylinder (220) a pick-up member (300), provided with a plurality of pick-up hooks (100) arranged according to a circular ring (310) about an axis (315) of the pick-up member (300), the circular ring (310) being divided into two circular half-rings (310a, 310b) of pick-up hooks (100) overturnable one onto the other, wherein each pick-up hook (100) comprises: a shank (101) movably constrained to the pick-up member (300), having a longitudinal axis (102) and ending with a hook portion (103); and a latch portion (105) having a stem (106), slidingly constrained to the shank (101) of the hook portion (103) along the longitudinal axis (102) of the shank (101), and a head (108) configured to co-act with the hook portion (103); wherein each latch portion (105) is constrained to the shank (101) of the hook portion (103) of the respective pick-up hook (100), such that each latch portion (105) participates integrally with the movement in radial direction of the hook portion (103) toward and away from the axis (315) of the pick-up member (300), and each latch portion (105) is movable with respect to the respective hook portion (103) with a movement substantially parallel to the longitudinal axis (102) of the shank (101) of the pick-up hook (100), so as to be able to move, alternatively, to an open position and a closed position;

arranging each pick-up hook (100) in a first position, spaced from the tubular knitted article (10), wherein in said first position the head (108) of the latch portion holds the hook portion (103) open;

pivoting each pick-up hook (100), integrally with the latch portion (105), from the first position toward the tubular knitted article (10) to a second position, in which the hook portion (103) of each pick-up hook (100) engages the tubular knitted article (10) and sliding the stem (106) of each latch portion (105) of each pick-up hook (100) along the longitudinal axis (102) of the shank (101) until closing the hook portion (103), thus preventing the tubular knitted article (10) from being released from the pick-up hooks (100);

removing the tubular knitted article (10) from the needle cylinder (220) by means of said pick-up member (300) and said pick-up hooks (100) engaged to the tubular knitted article (10);

overturning the two circular half-rings (310a, 310b) of the pick-up hooks (100) one onto the other, thus superimposing the two opposite edges of the open toe of the tubular knitted article (10) on each other;

joining the two opposite edges to each other forming a closed toe;

unloading the tubular knitted article (10) with the closed toe.
The method of claim 1, wherein the step of moving each pick-up hook (100) toward the tubular knitted article (10) comprises the step of inserting each pick-up hook (100) between two needles (210) of the needle bed to engage a portion of tubular knitted article (10) between consecutive needles (210).
The method of claim 1 or 2, wherein the step of moving each pick-up hook (100) toward the tubular knitted article (10) comprises the step of rotating each pick-up hook (100), integrally with the latch portion (105), with respect to the pick-up member (300), about a respective rotation axis (302) oriented at an angle of approximately 90° with respect to the axis (315) of the pick-up member (300), moving the hook portion (103) of each pick-up hook (100) toward the axis of the pick-up member (300).
The method of one or more of the preceding claims, wherein the step of joining the two opposite edges of the open toe of the tubular knitted article (10) to each other comprises the step of radially tensioning loop portions (32) outward, with respect to the axis (315) of the pick-up member (300), by means of a radial outward movement of the hook portions (103) of said pick-up hooks (100) integrally with the corresponding latch portions (105).
The method of one or more of the preceding claims, wherein on the pick-up member (300) a pick-up hook (100) every two needles (210) is provided, and the hook portions (103) of the pick-up hooks (100) are tapered in a front area facing the axis (315) of the pick-up member (300) and have a maximum transverse dimension (224) greater than the distance (226) between adjacent needles (210), the pick-up hooks (100) penetrating between alternate pairs of needles (210) increasing the distance (226) between pairs of adjacent needles (210) between which the pick-up hooks (100) penetrate and reducing the distance (226) between pairs of adjacent needles (210) between which the pick-up hooks (100) do not penetrate, making it possible to obtain stitch courses that are closer together with respect to the pitch of the needles (201) to perform fine gauge linking or sewing.
A pick-up device (318) for picking up tubular knitted articles (10) from a circular knitting machine (200), comprising a needle cylinder (220) with a circular needle bed; the device comprising:
a pick-up member (300) provided with a plurality of pick-up hooks (100) arranged according to a circular ring (310) about an axis (315) of the pick-up member (300), the circular ring (310) being divided into two circular half-rings (310a, 310b) of pick-up hooks (100) overturnable one onto the other, wherein each pick-up hook comprises a shank (101), having a longitudinal axis (102) terminating with a hook portion (103) movably constrained to the pick-up member (300);

a handling device (350) configured to move the pick-up member (300) between at least two operating positions;

an overturning device (305), for overturning the circular half-rings (310a, 310b) of pick-up hooks (100) one onto the other;

a drive device (330) of the pick-up hooks (100) for moving each pick-up hook (100) with respect to the axis of the pick-up member (300), wherein each pick-up hook (100) comprises a latch portion (105) having a stem (106) slidingly movable along the longitudinal axis (102) of the shank (101) and a head (108) coacting with the hook portion (103); characterized in that each latch portion (105) is constrained to the shank (101) and to the hook portion (103) of the respective pick-up hook (100), such that each latch portion (105) participates integrally with a movement in radial direction of the hook portion (103) toward and away from the axis (315) of the pick-up member (300), and each latch portion (105) is movable with respect to the respective hook portion (103) with a movement substantially parallel to the longitudinal axis (102) of the shank (101) of the pick-up hook (100), so as to be able to move, alternatively, to an open position and a closed position; and wherein a control device is provided to slide each latch portion (105) along the shank (101) of the respective pick-up hook (100) between a first position, in which the head (108) holds the hook portion (103) open, and a second position, in which the head (108) closes the hook portion (103) to retain the tubular knitted article (10).
The pick-up device of the claim 6, wherein each pick-up hook (100) is provided, with respect to the pick-up member (300), with a pivoting movement so as to move the hook portion (103) radially toward and away from the axis of the pick-up member (300), the latch portion (105) moving integrally with the pick-up hook (100) in said rotation movement.
The pick-up device of claim 7, wherein the shank (101) of each pick-up hook (100) has a shape selected from:
a laminar shape having at least one protrusion (101b), the stem (106) of the latch portion (105) having at least one slot (106b) in which the protrusion (101b) of the shank is slidingly engaged;

a laminar shape having at least one slot (106c) and the stem (106) of each latch portion (105) having at least one protrusion (101c) that is slidingly engaged in the respective slot (106c);

a box shape comprising an inner sliding seat (101a) in which the stem (106) of the corresponding latch portion (105) is housed.
The pick-up device of one or more of claims 6 to 8, wherein the shank (101) of each pick-up hook (100) has a fixing portion (104) to constrain the pick-up hook (100) in a movable manner to the pick-up member (300).
The pick-up device of claim 9, wherein the fixing portion (104) is formed by two opposite halves (104a, 104b) at least one of which is connected in a cantilever fashion to the shank (101).
A system for producing tubular knitted articles (10), comprising:
a circular knitting machine (200) with a needle cylinder (220) comprising a circular needle bed;

a pick-up device (318) as claimed in one or more of claims 6 to 10;

a closing device (500) provided with sewing needles (505) to close two opposite edges of a toe of the tubular knitted article (10).
The system of claim 11, wherein the pick-up hooks (100) are adapted to be inserted each between two adjacent needles (210) of the circular needle bed (210).
The system of claim 11 or 12, wherein on the pick-up member (300) a pick-up hook (100) is provided every two needles of the circular needle bed, and wherein the pick-up hooks (100) have a hook portion (103) whose front section facing the axis (315) of the pick-up member (300) has a maximum transverse dimension (224) greater than a distance (226) between adjacent needles (210) of the circular needle bed (210).
The system of claim 11, 12 or 13, wherein the pick-up hooks (100) have a tapered shape configured to penetrate between pairs of adjacent needles (210).