Technical Field

This invention relates to a folding apparatus for textile machines, that is to say, an apparatus for folding the fabric so that its longitudinal edges are substantially superposed.

This invention also relates to a sewing machine designed to sew said superposed edges to form a continuous tube.

Background Art

Therefore, the term tube or fabric in the form of a tube refers to a tubular piece of fabric of any length.

The process of folding and/or folding and sewing the edges is a necessary preparatory step for many processing operations in the textile sector.

A prior art fabric folding apparatus, usually integrated in sewing machines, comprises a frame to which an open fabric from a roll or layer is fed. The open fabric enters the machine through two tensioning cylinders then two stretching cylinders which stretch it and immediately adjust its tension. The fabric then passes through a complex centring system consisting of an optical cylinder which continuously electronically detects the centre line of the fabric and a cylinder with controlled mobile lugs. When the fabric moves transversaliy, the system processes the signal and controls the lugs of the cylinder, making them move the opposite way to the movement of the fabric. In this way, the fabric always remains centred relative to the centre line. The fabric is then fed forwards to a folding triangle fixed to the machine frame. In particular, the fabric slides on the folding triangle in a first feed direction, and the triangle diverts the fabric, directing it in a second feed direction which is transversal to the plane in which the triangle lies. In this way, the folding triangle folds the fabric at a fold line.

To obtain this result, the base of the folding triangle is positioned transversally to the fabric first feed direction. The folding triangle is also angled in such a way that as the fabric is fed forwards it reaches first the base and then the tip opposite it. Said tip, also called the folding tip, is also equidistant from two lateral edges of the fabric. In particular, the folding triangle has the shape of an isosceles triangle, so that it folds the fabric into two identical longitudinal parts.

The approaching fabric makes contact with the upper face of the folding triangle, Then the fabric passes beyond the triangle, being wrapped over it and adhering to it at the two oblique sides. The fabric is then folded, and a fold line develops from the folding tip in a direction substantially parallel with the fabric second feed direction.

Once folded, the fabric proceeds in the second feed direction. The fabric then passes at a centring device, comprising two first centring bars, which bring the two longitudinal edges of the fabric towards one another. In particular, the fabric is interposed between the first centring bars. Moreover, the first centring bars may slide relative to each other, in such a way that each bar pulls a respective edge. This allows the two edges of the fabric to be moved in order to compensate for any misalignments,

Once the edges have been brought towards each other, the fabric passes through a pair of second centring bars, like the first bars, but closer together and having a reduced travel relative to one another. These second centring bars are designed to precisely position the edges of the fabric and to press them against each other, for example in preparation for sewing.

If the folding apparatus described is part of a sewing machine, once the edges have been precisely positioned, the fabric passes at a sewing device, which applies a line of stitching parallel with the fold line. The machine also comprises sensors, positioned between the sewing device and the centring device, able to detect any misalignment of the edges of the fabric and to send a signal to a control unit. The control unit processes the signal and adjusts the centring device according to the signal for improved alignment of the edges of the fabric.

The prior art folding apparatus described above is not without disadvantages.

A first disadvantage is its significant construction complexity, due in particular to the presence of the complicated fabric centring system described above and the presence of two pairs of centring bars. Since each pair can be controlled independently, each requires a respective motor and a respective transmission. For these reasons the assembly, disassembly and maintenance of such an apparatus are complex and difficult.

Another disadvantage of the prior art apparatuses, also linked to the presence of the centring system using mobile lugs, is caused by the significant dimensions and weight of the system.

Disclosure of the Invention

In this context, the technical purpose which forms the basis of this invention is to propose a folding apparatus for textile machines that overcomes the above mentioned disadvantages of the prior art.

In particular, this invention has for an aim to provide a folding apparatus which is simple and practical to produce and easy to maintain.

Another aim of this invention is to provide a sewing machine in which a folding apparatus can be integrated and which is, as a whole, simple and practical to produce and easy to maintain.

The stated technical purpose and the aims specified are substantially achieved by a folding apparatus and a machine for sewing the fabric into a tubular shape having the technical features described in the appended claims.

Brief Description of the Drawings

Further features and advantages of this invention are more apparent in the detailed description below, with reference to preferred, non-limiting, embodiments of a folding apparatus and a machine for sewing the fabric into a tubular shape, illustrated in the accompanying drawings, in which: - Figure 1 is a schematic perspective view of a preferred embodiment of a folding apparatus for textile machines made in accordance with this invention;

- Figure 2 is a side view in cross-section, with some parts cut away for clarity, of a detail of the apparatus of Figure 1;

- Figure 3 is a perspective view of the apparatus of Figure 1 with some parts cut away to better illustrate others;

- Figure 4 is a schematic perspective view of a sewing machine equipped with an apparatus according to the previous figures.

Detailed Description of the Preferred Embodiments of the Invention

With reference to the accompanying drawings, the numeral 1 denotes in its entirety a fabric folding apparatus made according to this invention.

The apparatus 1 comprises a main frame 3 whose upper part supports a plurality of rollers, labelled 4 as a whole and only partly illustrated, for inserting, tensioning and feeding a fabric 6, and able to feed the fabric 6 arriving from a storage element, not illustrated, such as a roll or layers laid one on top of another.

The above-mentioned rollers are designed to feed the fabric 6 in a first feed direction A.

The apparatus 1 comprises a folding device 9 connected to the main frame 3. The folding device 9 acts on two longitudinal lateral edges 6b of the fabric 6, drawing them near each other and folding the fabric 6 along a fold line 6c. To obtain this result, the folding device 9 diverts the fabric 6 from the first feed direction A to a second feed direction B, which is set at an angle to the first feed direction. In particular, the second feed direction B for the fabric 6 is substantially parallel with the fold line 6c and preferably transversal to the first feed direction A.

Moreover, the folding device 9 can oscillate relative to the main frame 3. In particular, the angular position of the folding device 9 relative to the main frame 3 is adjustable, in such a way as to align the edges 6b of the fabric 6. In the embodiment described, as Figures 2 and 3 also show, the folding device 9 comprises a supporting frame 12, or secondary frame, and a folding triangle 5, which is supported by the secondary frame 12 so that it preferably lies in a plane containing the first feed direction A.

The folding triangle 5 comprises a base 5a opposite a folding tip 5b, the base being positioned transversally to the fabric 6 first feed direction A.

The folding triangle 5 also comprises two edges 5c, and the folding tip 5b is positioned away from the rollers 4 whilst the base 5a is towards the rollers.

In particular, the sides 5c of the triangle 5 meet at the folding tip 5b.

It should be noticed that the edges 5c of the folding triangle 5 each form a respective diverting portion 9a of the folding device 9. In particular, the edges 5 c of the folding triangle 5 are designed to divert the fabric 6 from the first feed direction A to the second feed direction B, The edges 5c are the oblique sides of the folding triangle 5 and, preferably, meet at the folding tip

5b.

In this way, the folding tip 5b corresponds to an end 9b shared by both of the diverting portions 9a. Said shared end 9b is preferably connected to the secondaiy frame 12 at a pin 10, In more detail, the edges 5c form an acute angle at the folding tip 5b,

The folding triangle 5 preferably has the shape of an isosceles triangle, so that it folds the fabric 6 into two identical strips 6a,

In other words, the fabric 6 is folded in half by the folding triangle 5, in such a way that the two lateral edges 6b, also called selvedges, make contact with each other. In this way, the strips 6a of fabric 6 are superposed.

In order to be able to rotate relative to the frame 3 and more particularly relative to the supporting frame 12, the folding triangle 5 is connected to the pin 10 at the folding tip 5b. Moreover, each edge 5c comprises an additional end 9c, preferably formed by the base 5a of the folding triangle 5. In particular, each end 9c of the folding device 9 can slide on the frame 12, preferably at a beam 11, shown with a dashed line, transparently, in Figure 3. Said beam 1 1 is substantially parallel with the axes of the rollers 4, and is positioned transversally to the fabric 6 first feed direction A.

To support the folding triangle 5, the secondary frame 12 comprises a plate 13.

In the embodiment described, as illustrated in the accompanying drawings, the folding triangle 5 is supported by the plate 13 which is in turn supported by the secondary frame 12, the latter being fixed to the main frame 3.

In particular, the supporting plate 13 preferably projects cantilever- style from the beam 11.

The plate 13 of the frame 12 substantially has the shape of a triangle, and it is preferably smaller than the folding triangle 5. The pin 10 is designed to allow the folding triangle 5 to oscillate at least partially relative to the supporting frame 12.

Figure 3 illustrates, with a dashed line, different positions adopted by the folding triangle 5 during its oscillation relative to the frame 12, about the pin 10.

During its oscillation, the folding triangle 5, resting on its lower face 5d, therefore slides on the above-mentioned plate 13 of the supporting frame 12.

As already indicated, the folding triangle 5 is preferably angled in such a way that the fabric 6, as it is fed forwards, reaches first the base 5a and then the edges 5c.

During operation of the apparatus 1, the fabric 6 makes contact with an upper face 5e of the folding triangle 5. Then the fabric 6 passes beyond the triangle 5, being at least partly wrapped over it and adhering to it at the edges 5c, The fabric 6 is then folded, and the fold line 6c extends from the folding tip 5b in a direction substantially parallel with the fabric 6 second feed direction B.

The apparatus 1 also comprises a pair of contact bars 14 acting on the fabric 6 and positioned so that they operate downstream of the folding device 9. The contact bars 14 are parallel with each other and are positioned transversally to the fabric 6 second feed direction B. Moreover, each contact bar 14 is in contact with a respective face of the fabric 6. In the preferred embodiment, the contact bars 14 are always in a horizontal position relative to the frame 3 but their height can be adjusted.

The contact bars 14 are designed to bring the strips 6a of the fabric 6 towards each other, for example in preparation for a subsequent sewing step.

In the embodiment described and illustrated, the folding apparatus 1 also comprises two elements 15 for smoothing the fabric 6, each acting on a respective strip 6a. Said smoothing elements 15 are preferably positioned downstream of the folding triangle 5, and are preferably located upstream of the contact bars 14. The smoothing elements 15 are designed to tension the edges 6b of the fabric 6 and prevent them from curling. In the embodiment described, each smoothing element 15 is in the form of a cylindrical bar positioned transversally to the fabric 6. In particular, each smoothing element 15 comprises a threaded surface 15a so that, when it grips the fabric 6, it can tension a respective edge 6b of the fabric and prevent it from curling. The smoothing elements 15 also rotate in opposite directions.

Advantageously, both of the smoothing elements 15 are driven by a single motor 8 so that they rotate at the same speed.

As illustrated in Figure 4, the folding apparatus 1 is incorporated in a sewing machine which therefore comprises a sewing device 16, fixed to the main frame 3 and preferably located downstream of the contact bars 14. The sewing device 16 acts on the edges 6b of the fabric 6, sewing them to form a tubular piece of fabric 6. The sewing device 16 is of the substantially known type, and therefore is not described in detail herein.

As already indicated, according to this invention, the angular position of the folding device 9, or rather the folding triangle 5, relative to the secondary frame 12 can be adjusted, in order to align the edges 6b of the fabric 6, thus obtaining two perfectly superposed strips 6a of fabric.

In the example embodiment of a sewing machine, said alignment of the edges 6b of the fabric must be achieved at the sewing device 16.

To control the movements of the folding device 9 triangle 5 and check the alignment of the edges 6b of the fabric, the machine 1 comprises an adjusting system, not illustrated.

In detail, the adjusting system comprises an optical sensor, also not illustrated, located downstream of the folding device 9. Said sensor is able to detect, instant by instant, any misalignment of the edges 6b of the fabric 6. In other words, the optical sensor operates on the fabric 6 in such a way as to detect a reciprocal position of the edges 6b of the fabric.

The above-mentioned adjusting system, not illustrated, also comprises a control unit (not illustrated). The control unit receives a first signal from the above-mentioned optical sensor and processes it. The control unit then sends a second signal to the folding device 9 so as to align the edges 6b of the fabric 6, In other words, the first signal represents the position of the edges 6b of the fabric relative to each other, whilst the second signal represents a correction of the position of the edges 6b of the fabric relative to each other. Moreover, the second signal is proportional to the first signal.

In the preferred embodiment, the control unit operates on an actuator (schematically illustrated with a block 19 in Figure 3) of the folding device 9 which is designed to make the folding triangle 5 oscillate relative to the secondary frame 12. In the preferred embodiment, the actuator 19 comprises a motor (not illustrated) supported by the secondary frame 12. In the preferred embodiment, the motor is an electric rotary motor.

In an alternative embodiment, the actuator 19 may be a linear actuator, for example a cylinder.

In more detail, the actuator 19 also comprises a transmission element (not illustrated) operating between the motor and the base 5a. By way of example, the transmission element comprises a male screw (not illustrated), connected to the motor and a female screw (not illustrated), driven by the male screw and stably connected to the folding triangle 5 at its base 5 a, preferably by means of an articulated joint (not illustrated). The male screw is positioned substantially parallel with the base 5a and is inserted in the female screw. The rotation of the motor is transmitted to the male screw, which is coupled to the female screw.

According to alternative embodiments of this invention not illustrated, the folding triangle comprises not a continuous triangular surface, but a triangular frame, for example comprising bars or tubular elements which respectively form its base and its two sides. The invention achieves the preset aims.

The fabric folding apparatus and the sewing machine in which it is integrated, made according to this invention, are practical and inexpensive to make and easy to maintain, since the mobile folding device makes the centring bars and the centring system using mobile lugs superfluous, thus reducing the components of which the apparatus consists and simplifying its construction, assembly and disassembly.

The apparatus is also very compact, since the mobile centring device allows errors in the positioning of the edges of the fabric to be compensated for without the need for centring bars.