Device and method for sewing the toe of a tubular knitted article

DESCRIPTION FIELD OF THE INVENTION

A device is disclosed for closing, by means of sewing, a toe of a tubular knitted article, such as a sock, a stocking, or a leg of a pantyhose. Also disclosed is a method for closing, by means of sewing, the toe of a tubular knitted article. BACKGROUND ART

In the hosiery industry, it is known to produce tubular knitted articles, such as stockings or socks, on a circular knitting machine, and to unload the complete tubular article, with an open end or toe, intended to be closed by means of sewing in a subsequent processing step. In some cases, the tubular knitted article is a leg of a more complex garment, in particular a pantyhose. The garment can be formed by two legs and by a body that can in some cases be knitted in a single operation on a knitting machine. According to more conventional methods, the garment is produced by joining two legs, formed by respective tubular knitted articles produced separately to one another. In some cases, the toe of the stocking or the toes of the legs of the pantyhose are closed in the same circular knitting machine that produces the garment or part thereof. More frequently, the toes of the tubular knitted articles, whether individual stockings, pantyhose legs or similar garments, are closed by sewing in separate machines, downstream of the knitting process. Sewing machines are used for this purpose, to which the tubular knitted articles are fed after they have been correctly ori- ented.

As the closed toe of the tubular knitted article must adapt to the toe of the foot of the person wearing the garment, it is useful for the seam line to be curved rather than rectilinear and in particular to follow a convex profile, which approximates the curvature of the toes of the foot toes. To this end, devices have been designed, which feed the tubular knitted article to the sewing machine imposing a deformation on the toe of the tubular knitted article such that, by sewing according to a straight line, a curved seam line is obtained. Devices of this type are disclosed in US4,609,419 and in DE2524238.

In these known devices, the area of the tubular knitted article adjacent to the - - toe is clamped between a feed belt and an opposing surface. The belt is an endless belt and defines a closed path. The active branch of the closed path draws the tubular knitted article from an insertion area to a sewing area. In the insertion area, the belt forms a curve corresponding to the profile of the seam line to be formed on the toe. In the sewing area, the belt follows a rectilinear path. Due to the change of curvature of the belt from the insertion area to the sewing area, in the finished article the seam line takes a convex profile, which adapts to the profile of the foot toe.

Due to the way in which the curved profile is formed, in the sewn tubular knitted article wrinkles form at the seam line, which can make the garment somewhat uncomfortable.

Therefore, there is the need to improve the devices for sewing the toes of tubular knitted articles, such as stockings or pantyhose legs, in order to overcome or alleviate the aforesaid problems.

SUMMARY OF THE INVENTION

To completely or partially solve one or more of the problems of the prior art, according to a first aspect a device for sewing a toe of a tubular knitted article is provided, comprising a continuous flexible member, configured and arranged to press with a branch thereof an end portion of the tubular knitted article against an opposing surface and to feed the tubular knitted article along a feed path from an insertion position toward and through a sewing area in which a sewing machine is arranged, for sewing the toe of the tubular knitted article. In the insertion position the branch of the continuous flexible member that presses the tubular article against the opposing surface forms a first curve. In the sewing area, the continuous flexible member co-acts with a convex deflector profile, along which the continuous flexible member is guided, and which imparts to the continuous flexible member a curvature with a convexity facing the same part as the convexity of the first curve of the continuous flexible member.

With this arrangement, a seam is generated according to a curved line, the shape of which is defined by the first curve formed by the continuous flexible member. However, in the area in which the sewing machine acts the fabric of the tubular knitted article is not deformed, or is deformed to a limited extent, due to the deflector profile, and therefore the formation of wrinkles in the sewn article is prevented or reduced. - -

The device can also comprise an inserter, to transfer the tubular knitted article from a first position to the insertion position between the continuous flexible member and the opposing surface. The first curve has a convexity facing in the direction of feed of the tubular knitted article from the first position to the insertion position.

In some embodiments, the continuous flexible member forms, between the first curve and the convex deflector profile, a curved segment with a concavity opposite to the concavity of said first curve. In practice, along the active branch thereof, the flexible member follows an undulating profile.

The deflector profile can be formed by an idler wheel, or by a stationary cam. Advantageously, the deflector profile can comprise a maximum point, positioned approximately at the sewing point of the sewing machine.

In advantageous embodiments, the deflector profile is adjustable at least in a direction approximately orthogonal to the feed path of the tubular knitted article. Analogously, the idler and guide members that define the curve or curves of the flex- ible member in the insertion area of the tubular knitted article can also be adjusted. Said members can comprise a plurality of idler wheels and/or of stationary cam profiles, on which the continuous flexible member is guided.

According to a further aspect, a method is provided for sewing a toe of a tubular knitted article, comprising the steps of:

engaging an end of the tubular knitted article between an opposing surface and a continuous flexible member, which forms in the engaging area a curve with a convexity facing the toe of the tubular knitted article;

transferring the tubular knitted article by means of the continuous flexible member along the opposing surface toward a sewing area, imparting to the toe of the tubular knitted article a curvature inverse to the curve of the continuous flexible member in the area of engagement;

sewing the toe of the tubular knitted article by means of a sewing machine while feeding the toe of the tubular knitted article through a sewing area by means of the continuous flexible member, in the sewing area the continuous flexible member being curved according to a curvature having a convexity facing the sewing machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by following the description and accompanying drawing, which shows practical non-limiting embodiments of the inven- tion. More specifically, in the drawing:

Fig. 1 shows an axonometric view of the device, including a sewing machine;

Fig.2 illustrates an axonometric view of the device with parts removed, in which the flexible member and its path are in particular visible;

Fig.3 illustrates a lateral view of the inserter, of the flexible member and of the elements co-acting therewith in a first step of the sewing cycle;

Fig.4 illustrates a plan view of the inserter in the layout of Fig. 3;

Figs. 5 to 12 illustrate views similar to Figs. 3 and 4 in subsequent steps of the operating cycle;

Figs. 13 to 15 show plan views of the sewing operations in subsequent steps of the operating cycle.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.

Reference throughout the specification to "one embodiment" or "an embodi- ment" or "some embodiments" means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

In the following description reference is made to an exemplary embodiment of a device for sewing the toes of tubular knitted articles formed by already assembled pantyhose legs. Each tubular article is thus formed by one of the two legs that, joined to a panty, form a complex garment. Sewing of the toes of the two legs of a pantyhose takes place in sequence. However, as will be apparent to the person skilled in the art from the description below, the device can be easily modified to produce single tubular knitted articles, such as socks or stockings, or legs intended to be joined to each other to form a pantyhose. - -

With initial reference to Figs. 1 and 2, the device, indicated as a whole with 1 , comprises a cluster 3 of members for inserting and feeding tubular knitted articles, and a stitcher or sewing machine 5. The sewing machine 5 can be an overlock sewing machine, of known type. The sewing machine sews the toe of the article and cuts a scrap of fabric, external to the seam line.

The cluster 3 comprises a continuous flexible member 7, which can, for example, be a belt and shall be designated as such hereinafter. The belt 7 defines a closed path with an active branch and a return branch. For this purpose, the belt 7 is guided around two pulleys 9, 10, one of which is motorized, for example the pulley 9. Reference number 11 indicates a gear motor to drive the belt 7. Reference f7 indicates the direction of feed of the belt 7 along the closed path defined thereby. Adjustable idler wheels or pulleys are provided along the active branch of the belt, which impose on the belt 7 a path that forms two curves 7A, 7B. The first curve 7A is positioned between two idler wheels 13, 15. A central idler wheel 17 is positioned in an intermediate position between the idler wheels 13, 15. The belt 7 is guided around the central idler wheel 17 so as to follow, in substance, a curved path with a maximum at the central idler wheel. The second curve 7B is formed between the idler wheel 15 and a further idler wheel 19. A further central idler wheel 21 is positioned between the idler wheels 15, 19.

In the exemplary embodiment shown, five idler wheels 13, 15, 17, 19, 21 are provided, as the device is configured to handle pantyhose and therefore to process two legs simultaneously, each of which defines a respective tubular knitted article. In other embodiments, if the device is configured to handle single tubular knitted articles only, such as socks or stockings, it is sufficient to arrange a single curve in the closed path formed by the belt 7.

The curves 7A and 7B are arranged with a concavity facing the area from which the tubular knitted articles arrive and a convexity facing the toe of the tubular knitted article, after it has been inserted in the device 1, as explained below. The tubular knitted articles are inserted under the belt 7 by an inserter, described below.

Reference F indicates the direction of feed of the tubular knitted articles toward the sewing machine 5 along the path defined by the belt 7. In practice, the active segment of the belt 7 defines, in a system of Cartesian axes, of which F is the abscissa, an undulating line with two maxima, at the two central idler wheels 17, 21.

In advantageous embodiments, the idler wheels 13, 15, 17, 19, 21 can be sup- - - ported idle and rotate about respective axes as a result of the movement imparted to the belt 7 by the gear motor 11. In some embodiments, one, some or all of the idler wheels 13, 15, 17, 19, 21 can be adjustable. For example, the position of their respective rotation axes can be adjustable, independently from one another, orthogonally to arrow F. In some embodiments, alternatively or in addition to the adjustment orthogonally to the arrow F, an adjustment in a direction parallel to the arrow F can also be provided. By means of the adjustment of the position of the rotation axes of the idler wheels it is possible to modify the shape of each curve 7A, 7B according to necessity. For example, it is possible to modify the two curves 7A, 7B so that each curve is not symmetrical, but the two curves are symmetrical to each other with respect to a line orthogonal to the arrow F and containing the axis of the intermediate idler wheel 15. In this way, as will be apparent below, seam lines can be made on two legs of a pantyhose, which have symmetrical shapes instead of being the same for the toes of the two legs.

A convex deflector profile 25 is provided between the idler wheel 19 and the idler pulley 10, along the path of the active branch of the belt 7. In the embodiment illustrated, the convex deflector profile 25 is a stationary profile, formed in the manner of a cam. The belt 7 is guided around the convex deflector profile 25 and slides thereon. It would also be possible to replace the stationary convex deflector profile 25 with a deflector wheel, for example mounted idle, around which the belt 7 is guided.

The convex deflector profile 25 has a convexity oriented in the same direction as the convexity of the curves 7A, 7B formed by the belt. In substance, as shown in the figures, the convexities of the curves 7A, 7B and of the deflector profile 25 are all oriented in the direction indicated by the arrow C. Consequently, when guided around the idler wheels 17 and 21 the belt is deflected to form a curve that has the convexity oriented in the same direction as the convexity imparted to the same belt 7 when it follows the convex deflector profile 25.

The convex deflector profile 25 follows a curve with a maximum point 25m. The maximum point 25m can be advantageously positioned in the sewing area of the sewing machine 5, i.e. in the area in which the sewing needles of the sewing machine 5 act, area indicated with 27 in the drawing. The needles are not shown in the drawing.

In other embodiments, not shown, the idler wheels 17 and 21 can be replaced - - by cam deflector profiles, similar to the deflector profile 25. In some embodiments, the idler wheels 13, 15, 19 can be completely or partially replaced by stationary cam profiles. In general, both the convex deflector profile 25, and any profiles in substitution of one or more of the idler wheels 13-19 can be made of materials with a low coefficient of friction, to facilitate sliding of the belt 7.

The device 1 comprises an opposing surface that can be formed, completely or partially, by a supporting surface 31. The supporting surface 31 can extend along the active portion of the path defined by the belt 7, at least in the section thereof where the belt 7 forms the curves 7A, 7B and the curve around the convex deflector profile 25. In some embodiments, the supporting surface 31 is at least partially formed by a moving plate 33, provided with a substantially vertical movement, in the example, orthogonal to the direction of feed F of the tubular articles. The movement of the moving plate 33 is indicated by the double arrow f33 and can be controlled by an actuator 35, for example a piston-cylinder actuator, or by an electric motor or oth- er suitable actuator.

In the embodiment illustrated, the moving plate 33 co-acts with a moving presser 37, positioned above the supporting surface 31 and provided with a movement parallel to the movement of the moving plate 33, indicated with the double arrow f37. Reference number 39 indicates an actuator that controls the movement ac- cording to the double arrow f37. The moving plate 33 and the moving presser 37 are positioned one in front of the other to pinch there between the toe of the tubular knitted article to be sewn, as will be described below with reference to the sequence of Figs. 3-15, which show the operating cycle of the device.

In the embodiment illustrated, the device 1 also comprises an inserter 41, which is configured and arranged to insert pairs of legs to be sewn transferring them from a first position to a second position, indicated hereinafter as insertion position, in which the toes of the legs are between the moving plate 33 and the active branch of the belt 7. The insertion movement of the tubular articles performed by the inserter 41 is indicated by the arrow f41. In the embodiment illustrated the inserter 41 is con- figured to simultaneously insert two legs Gl , G2 of a pantyhose Co between the belt 7 and the supporting surface 31 and therefore has a double configuration. In other embodiments, in particular if the tubular knitted articles to be sewn are not legs Gl , G2 of a pantyhose Co, but single stockings, for example, the inserter 41 can be single, i.e., configured to insert tubular knitted articles one at a time between the belt 7 - - and the supporting surface 31.

In the example illustrated the inserter 41 comprises two tubular members 43 A, 43B, on each of which one of the two legs Gl, G2 is inserted. A pair of wings, 45A, 45A and 45B, 45B respectively, can be housed inside each of the two tubular members 43A, 43B. The wings can be movable axially, i.e., parallel to the axis of the respective tubular member 43A, 43B, and transverse to said axis, to extract the respective leg Gl , G2 removing it partially from the tubular member 43 A, 43B, taking it between the belt 7 and the underlying supporting surface 31 , with a movement described below.

Each tubular knitted article formed by the leg Gl or G2 can have, at the end of the toe to be sewn, an edge B that is removed by cutting after or during sewing of the toe. The seam line is located inside the edge B, so that this latter can be cut and removed from the finished article, leaving intact the seam that closes the respective toe of the leg Gl or G2, respectively.

Operation of the device described above will now be illustrated in detail with reference to the sequence of Figs. 3 to 15. Figs. 3 and 4 show an initial step of positioning the pantyhose Co and in particular the two legs Gl, G2. The wings 45 A, 45 A and 45B, 45B have been extracted transversely from the respective tubular members 43A 34B and the respective legs are stretched orthogonally to their longitudinal ex- tension.

In the subsequent step illustrated in Figs. 5 and 6 the wings 45A, 45A and 45B, 45B are extracted longitudinally from the respective tubular members 43 A, 43B and, as a result of the friction between wings and fabric of the legs Gl, G2, these latter are drawn by the wings until the respective toes and edges B are taken below and beyond the belt 7, between it and the underlying moving plate 33, carrying out a movement according to the arrow f41. In practice, each tubular knitted article formed by the leg Gl or G2 has in this way been translated from a first position (Fig. 3) to an insertion position (Fig. 5). The respective convexities of the curves 7A, 7B of the belt 7 are facing the edges B of the two tubular knitted articles Gl, G2, which are on the opposite part of the belt with respect to the initial position.

In the subsequent step (Figs. 7, 8), the moving plate 33 and the moving press- er 37 are moved toward each other (arrows f33, f37 in Fig.7) to pinch the two tubular knitted articles Gl, G2 against the wings 45 A, 45A and 45B, 45B. Preferably, the stroke of the moving plate 33 and of the moving presser 37 is such that the total - - bending stress applied on the wings 45A, 45A and 45B, 45B is substantially zero, thereby avoiding bending strain of the wings.

Subsequently (Figs. 9, 10) the wings 45 A, 45 A and 45B, 45B are retracted, while the two tubular knitted articles Gl and G2 remain pinched between the moving plate 33 and the moving presser 37. In practice, the friction between the fabric of the legs and the elements 33, 37 is greater than the friction between fabric and wings, so that the wings are removed from the inside of the legs, which remain blocked between the moving presser 37 and the moving plate 33.

Once the wings have been retracted, the moving presser 37 and the moving plate 33 are raised until the moving plate 33 is presses against the lower edge of the belt 7. In this way the two toes of the two tubular knitted articles Gl , G2 are pinched between the moving plate 33 and the lower edge of the belt 7. The moving presser 37 can be moved to a non-operating position, i.e., a raised position not in contact with the underlying tubular articles Gl, G2. This new position is represented in Figs. 11 and 12.

During the operations described above the belt 7 is stationary. After reaching the position of the Figs.11 and 12, the belt 7 can start moving according to arrow f7, to feed the two tubular knitted articles Gl, G2 toward the sewing area. Each tubular knitted article Gl, G2 is engaged along a curve defined by the belt 7, between this latter and the moving plate 33. When the belt 7 starts moving according to arrow f7 (Fig.13), it draws each tubular knitted article Gl, G2 by friction, according to the arrow F, along the supporting surface 31 toward the sewing area, where the sewing machine 5 is located.

As a result of the curvature imparted to the belt 7 by the idler wheels, when each tubular knitted article Gl and G2 follows the path of the belt 7, adhering by friction to the lower edge of the belt 7, it is deformed. The line of contact between tubular knitted article Gl, G2 and belt 7 is deformed and, as a consequence of this, the edge B of the tubular knitted article Gl, G2 takes a concave shape.

Continuing the feed toward the sewing area, the tubular article Gl, G2 re- mains in contact without sliding with the belt 7 and therefore follows the curvature of the convex deflector profile 25. While it is being fed, at the maximum point 25m of the curve defined by the convex deflector profile 25, the tubular knitted article Gl, G2 is sewn by the sewing machine 5, as represented schematically in the plan view of Fig. 14. This figure shows an intermediate step of the operation to sew the leg Gl . - -

Reference L indicates the seam line that has been made on half of the toe of the leg Gl by the needle (not shown) of the sewing machine 5 that acts in the point 27. The edge B of the toe of the tubular knitted article Gl has been cut along the area involved by the seam L, while it still remains in the area that has not reached the point 27 in which sewing takes place.

In Fig 15 a pantyhose Co has been completely sewn: the toes of the two tubular knitted articles represented by the two legs Gl, G2 have been sewn along curved and convex seam lines L, which approximately follow the profile of the toe of the foot. The subsequent pantyhose, indicated here with CI, is being sewn: the first leg Gl of the pantyhose CI has been sewn, the second leg G2 is being sewn. A third pantyhose C3 is standing by to be inserted into the operating position.

Due to the presence of the convex deflector profile 25, in the point 27 in which sewing takes place the fabric of the tubular knitted article Gl, G2 is forced to follow the convex deflector profile 25 which locally annuls the deformation imposed on the knitted fabric by the movement imparted by the belt 7 in the previous section of the feed path, between the curves 7A or 7B and the idler wheel 15 or 19. As the convexity of the curve 7A or 7B and the convexity of the deflector profile 25 are oriented in the same direction (arrow C), in the sewing area (point 27) in substance the fabric of the tubular knitted article is in a practically unde formed condition. Consequently, as the resulting seam line L is curved, due to the sum of the effects of the curves 7A or 7B and of the convex deflector profile 25 on the knitted fabric of the tubular knitted article Gl, G2, the fabric is sewn substantially without wrinkles.