ITFI20130035A1 - AUTOMATIC FRAME FOR TRIASSIAL FABRICS WITH VARIOUS TYPES OF CROSSINGS. - Google Patents

Description

DESCRIPTION

AUTOMATIC LOOM FOR TRIAXIAL FABRICS WITH VARIOUS TYPES OF CROSSES.

Technical field

The present invention belongs to the field of automatic looms for the production of triaxial fabrics. In particular, of so-called two-dimensional triaxial fabrics.

State of the art

The automatic loom is a machine used for the production of fabrics by means of the appropriate intertwining of the threads, called weft and warp, usually perpendicular to each other. In the industrial field, said machine is usually integrated with other machines that perform auxiliary functions, such as the feeding of the threads necessary for the formation of the fabric, or of thin strips called tapes, used in place of the threads. The result of the intertwining of the weft and warp threads is a two-dimensional fabric, characterized by two axes which are substantially perpendicular to each other. This arrangement limits both the visual and tactile effects that can be obtained, and the mechanical properties of the fabric.

For the reasons just highlighted, starting from the end of the seventies, the two-dimensional triaxial fabric, composed of a series of warp threads and two different series of weft threads, has been the object of particular attention, mainly for its high characteristics structural and mechanical resistance.

In US 3446251 (A) some variants of triaxial fabric are described. Numerous patent applications, including those citing the aforementioned application, highlight both the different characteristics and the variety of applications of this type of fabric.

Usually in triaxial fabrics both series of weft threads cross a single series of warp threads, forming with the latter an angle close to 60 sexagesimal degrees; the fabric thus obtained offers great stability and uniform resistance to cutting and tearing efforts. However, many other types of fabric can be obtained by varying the crossover modes, angles or other parameters.

An example of a triaxial fabric (1) of the two-dimensional type is shown in Fig. 1. The figure shows the directions of the warp and weft threads.

Machines for the production of triaxial fabric are known which sew or glue superimposed fibers or threads. For example, a two-dimensional fabric with a weft orthogonal to the warp, can be transformed into a two-dimensional fabric with an oblique weft and then sewn with a third thread in order to produce a triaxial fabric. Similar systems are described in numerous patent applications, including application EP 0250044 (A1). However, it is found that the principle of superimposing two layers of threads, one of which is oblique, has been known for some time and is, for example, already described in US 2985941 (A).

These systems show numerous limitations, both from the point of view of the process and the characteristics of the finished product. For example, the glues, powders or films used require special attention during use, as well as being subject to phenomena characterized by high variability. Furthermore, the sewing requires particularly complex and delicate machinery and the weave obtained does not allow the threads to be blocked as it would be preferable.

It follows that the fabric thus obtained is not comparable to that produced by machines that actually cross the threads.

Patent application US 3799209 (A) describes a machine particularly suitable for the production of triaxial fabric, of the type described in the aforementioned application US 3446251 (A). In the weaving machine described in the aforesaid application, the warp yarns are guided by a series of heddles which move them in such a way as to allow them to cross each other. During this movement, openings are formed, otherwise called steps, which are used for the insertion of the weft thread. This machine, developed starting from known principles and mechanisms, is extremely complex and bulky. In fact, the movements of the elements of the machine must be very accurate and the mechanism just described must be repeated for a large number of times in order to obtain a strip of fabric that extends for an appreciable width, so that the repetition of numerous auxiliary handling elements.

The aforementioned problems have remained inherent in the technology up to now, as they have not been resolved by subsequent patent applications. For example, application US 3999578 (A) describes some improvements for the insertion of the weft thread which, however, do not solve the above problems.

Aims and summary of the invention

The present invention intends to respond to the problems highlighted above by reducing both the complexity of the systems used and the overall dimensions of the loom with respect to the width of the fabric formed. These characteristics are obtained thanks to the combined use of an innovative oblique weaving front and a combined system for guiding the warp yarns and feeding the fixed oblique weft yarns.

In this text the weaving front F corresponds to the inserted oblique weft thread direction.

In the loom object of the present invention said weaving front F is oblique, i.e. the direction is incident, but not perpendicular to the direction X of the warp yarns (21). This detail appears clearly in Fig. 2.

The loom for triaxial fabric (1) object of the present invention can produce fabrics starting from textile materials in different forms, such as, by way of example but not limited to, threads, tapes, multi-filament threads. In order to adapt the operation to the various materials and to the needs of industrial automation, the feeding group (2) of the series of warp yarns can assume different shapes, for example it can consist of one or two beams (22) or of one or more creels.

The warp yarns are moved, by means of the traction exerted by the piece, by a feeding unit (3). In fact, the dragging of the warp takes place, preferably, by means of the traction exerted by the already formed piece of fabric (1) which winds on the motorized reel (31).

Advantageously, said advancement unit (3) can comprise one or more motorized cylinders whose lateral surfaces exert an auxiliary action of dragging by friction on the already formed piece of fabric (1).

Alternatively, said one or more motorized cylinders can exert a traction sufficient for the traction of the piece and / or the dragging of the warp yarns. In addition, advantageously, said one or more motorized cylinders can also be placed before the weaving front F so as to facilitate unthreading from the creel or unwinding from the beam or beams.

In the event that one or more motorized cylinders are present both upstream and downstream of the weaving front F, the former carry out a function of unwinding or pulling out the warp yarns (21), the latter pulling the piece of triaxial fabric (1), both also act on the tensions that occur on the wires. The size of the latter responds to different needs that arise in the various areas of the frame. For example, said tensions can facilitate the passage of the cursor on the weaving front or prevent the piece from being placed in a state that could cause it to break or fold.

As will be better described later, also the group (4) for inserting the thread (41) of oblique fixed weft contributes to the control of the tensions.

The unit (2) for feeding the warp yarns (21) arranges said yarns on a single plane or on two planes, using suitable transmission means or devices known in the field.

To facilitate the subsequent insertion of the inserted oblique weft yarn (51), the warp yarns (21) can be kept spaced from the oblique fixed weft yarn (41) by means of a board (8). If the warp yarns are fed on two different planes, a table (8a, 8b) is conveniently adopted for each feeding plane.

Conveniently, said boards (8a, 8b) can be suitably shaped so as to modify the tensions generated in the warp yarns and / or the directions of said warp yarns.

The assembly (4) for inserting the oblique fixed weft thread (41) comprises means for moving said oblique fixed weft thread just arranged. Said handling means transport the previously positioned oblique fixed weft thread along the X direction, after having been unwound from a feeding bobbin.

The oblique fixed weft yarn (41) is positioned with the use of devices known in the field, for example by means of a weft feeder slider (46) which slides on a guide parallel to the weft already positioned and which is fed by a reel placed on cylinders (44, 45) on which it rotates, thus unwinding without causing the yarn to twist.

Conveniently, said means for moving the oblique fixed weft can comprise two lateral dragging tracks (42, 43) which can have guide elements for said yarn (41). Said two lateral tracks (42, 43) can be replaced by equivalent devices, such as chains or belts. Advantageously, the external lateral surface of each of said lateral tracks (42, 43) can have a plurality of reliefs (421, 431), around which said thread (41) of oblique fixed weft is returned. In a preferred form, said reliefs (421, 431) have a substantially cylindrical shape. Said lateral tracks (42, 43) can, however, be operated independently, in order to distribute the tensions differently or facilitate the insertion of the inserted oblique weft thread (51) or to obtain compacting effects of the fabric (1 ) already formed. As mentioned above, the action of said tracks (42, 43) can be coordinated with that of one or more of the possible motorized cylinders of the advancement group (3).

Furthermore, said lateral tracks (42, 43) may not be parallel to each other in order to limit the tensions that the yarn guide elements (7) or the spreaders (10) generate on the yarns.

Moreover, the tension of the oblique fixed weft yarn (41) arranged between the lateral tracks (42, 43) is also controlled by means of the said weft feeder slider (46).

Said feeding unit (4) allows to arrange on the weaving front F the oblique fixed weft thread (41) oriented in an incident direction with respect to the direction X of the warp threads.

Unlike what happens in machines that simply superimpose the fixed weft threads on the warp threads, in the loom object of the present patent application, when the warp threads (21) are arranged on two planes, the thread (41 ) of fixed oblique weft is woven between the warp threads of one plane and the warp threads of the other plane.

The division of the warp yarns on two different planes can be obtained, indifferently, starting from one or more beams (22), if the said feeding system (2) uses a plurality of beams.

The triaxial fabric (1) is formed when the insertion unit (5) provides for the positioning of the inserted oblique weft thread (51). Said thread (51) of inserted oblique weft is guided between the warp threads by means of suitable systems usually used in the sector, such as systems with slider (9) and lance, or projectile or air systems or others.

The warp threads, with a fixed oblique weft and an oblique inserted weft, therefore follow three different directions which, in a particularly convenient embodiment of the invention, can form angles of sixty degrees.

As highlighted in the description of the state of the art, in the absence of interlacing, the presence of threads directed along three directions is not sufficient to form a triaxial fabric (1) proper.

In the invention which is the subject of the present application, the guiding elements (7) of the individual warp threads (21) raise some of them and lower the remaining ones, so as to form a space, aligned according to the weaving front F. At the same time, the weft thread inserted obliquely is made to slide transversely to the piece so as to form the weave.

In particular, the weaving does not concern only the inserted oblique weft yarn (51) and the warp yarns (21), but also the oblique fixed weft yarn (41). This last thread (41) moves towards the feed unit (3) in a coordinated way with the transversal crossing of the piece by the inserted oblique weft thread (51).

Thanks to said yarn guide elements, the inserted oblique weft yarn (51) passes alternately above and below each warp yarn.

The structure of the triaxial fabric (1) can be varied by acting on numerous mechanisms, some classics in the sector, others specific to this invention. A simple example of a classic variation is represented by the use of a variety of warp threads (21).

Specific effects of this invention can be obtained by acting both on the thread guide elements (7) and on the unit (4) for inserting the thread (41) of oblique fixed weft. In particular, by varying the arrangement of the yarn guide elements, numerous combinations of crossing and, therefore, of fabric can be obtained. For example, instead of placing the wire guide elements (7) alternately downwards and upwards, it is possible to alternatively provide several elements towards the top and only one towards the bottom, or vice versa. What has just been described allows to obtain multiple crossover combinations which involve the inserted weft yarn (51).

Furthermore, the yarn guide elements can be reduced or increased in number, also varying the spacing of the warp yarns (21).

Similarly, and possibly in a way coordinated with the variations just described, it is possible to act on the positioning of the yarn (41) with a fixed oblique weft, increasing or reducing the spacing between two parallel elements with a fixed oblique weft.

By coordinating the different groups of the invention object of the present application it is therefore possible to obtain different combinations of triaxial fabric (1).

The weaving can be further favored by the presence of some spreaders (10), which stabilize the position of the oblique fixed weft yarn (41). Said spreaders (10) are characterized by a substantially vertical reciprocating motion, coordinated with the sequence of crossing of the weaving front by the inserted oblique weft yarn (51).

The structure of the fabric obtained does not vary exclusively in reference to the interlacing and angles between the threads, but also on the basis of classical parameters in the field of automatic looms, such as the distance between the threads or their tensioning.

Said different structures can be obtained by acting on various mechanisms. For example, it is possible to vary the shape of the yarn guide elements, the speed of the belts of the insertion group (4) of the fixed oblique weft yarns, also providing for the independent actuation of the two sides. Furthermore, it is possible to act on the distance between the two tracks in order to also take into account the effects of the intertwining in the tensioning of the threads.

Brief description of the drawings

Fig. 1 shows an example of a triaxial fabric. At the center of the figure it is possible to observe the effect obtained while, at the edges, some threads have been removed in order to facilitate the identification of the warp threads and the oblique weft threads, both fixed and inserted.

The figure shows the X, Y and F axes representing the three directions of the triaxial fabric (1).

Fig. 2 shows an axonometric view of an embodiment of the frame object of the present patent application.

In order to facilitate the understanding of the figure, some elements have been removed. On the right side of the image is shown the unit (2) for feeding the warp threads (21); then the group (3) for feeding the warp threads (21), the group (4) for inserting the yarn (41) of oblique fixed weft and the group (5) for inserting the yarn (51) of the oblique weft insert. Furthermore, the guiding elements (7) of the warp threads (21) are visible. The figure shows the axes X, Y and F representing, respectively, the direction of the warp threads (21), the oblique fixed weft thread (41) and the weaving front.

Fig. 3 shows an axonometric view of a further embodiment of the loom, in which the warp threads are arranged on a single plane.

Fig. 4 shows a detail of the loom, where the yarn guide elements (7) of the warp yarns (21) are highlighted. The yarn guides (7) are aligned along the weaving front F and are installed on the boards (8a, 8b).

Fig. 5 shows a detail where the passage of the cursor (9) is highlighted, which drags the oblique weft thread (51) inserted along the weaving front F, from one part of the piece to the other, so as to form the triaxial fabric (1).

Fig. 6 shows the detail consisting of two yarn guide elements (7a, 7b) of two of the warp yarns (21a and 21b) and of the inserted oblique weft yarn (51) positioned by the cursor (9).

Fig. 7 shows a single thread guide element (7) of the type for webbing. The arrow inside the figure indicates the direction of advancement of the warp threads (21).

Fig. 8 shows a detail where the passage of the cursor (9) is highlighted, which drags the oblique weft thread (51) inserted along the weaving front F so as to form the triaxial fabric (1) according to a point of view different from that of Fig. 5 so as to highlight the function of the yarn guide elements (7).

Fig. 9a shows a detail of the frame where the expanders (10) are visible in the rest position.

Fig. 9b shows a detail of the frame where the expanders (10) are visible in the working position.

Fig. 10 shows an axonometric view of an embodiment of the assembly (4) for inserting the oblique fixed weft yarn (41).

Fig. 11 shows a detail of an embodiment of the unit (2) for feeding the warp yarns in the case that this comprises two beams (22a, 22b).

Detailed description of an embodiment of the invention

In a preferred embodiment, the frame object of the present application comprises:

a unit (2) for feeding the warp yarns (21) according to two planes, comprising a beam from which the two series of yarns arranged on said planes are generated; a group (3) for advancing the warp yarns (21); a unit (4) for inserting the oblique fixed weft yarn (41) where the latter is oblique with respect to the direction X of feeding the warp yarns; an assembly (5) for inserting the thread (51) of the inserted oblique weft arranged according to a weaving front F oblique both with respect to the direction X of feeding the warp yarns and with respect to the direction Y of insertion of the fixed oblique weft yarns.

In said loom the passage of the oblique weft thread (51) inserted from one part of the piece to the other, in the direction of the weaving front F, takes place by means of a cursor (9). Said passage is coordinated both with the movement imposed by the group (3) for feeding the warp yarns, and with the movement of the oblique fixed weft yarn (41) by means of the assembly (4) for inserting said yarn.

The warp threads (21) are pulled along the X direction by the feed unit (3) by means of the traction action exerted by the reel (31) on which the already formed piece of fabric (1) is wound. Advantageously, the advancement unit (3) comprises two motorized cylinders which perform an auxiliary dragging action on the already formed piece.

In the embodiment described here there are two boards (8a, 8b) between each plane containing the warp threads (21) and the oblique fixed weft thread (41).

Said boards (8a, 8b) are initially parallel to the horizontal planes on which the warp yarns (21) are located, initially arranged by the feeding unit (2) and then tapering so as to favor the change of direction imposed by the yarn guide elements (7 ) of the warp threads (21).

In fact, said loom comprises a plurality of guiding elements (7) of the warp yarns (21), aligned according to said weaving front F and such as to punctually raise or lower the warp yarns to facilitate the insertion of the yarn ( 51) of inserted oblique weft.

The geometry of the boards (8a, 8b) also makes it possible to vary the direction of the tensions on the warp threads (21) in proximity to the guiding elements (7).

Conveniently, said yarn guide elements (7) are supported by the two boards (8a, 8b) and consist of static elements suitably shaped to distance the warp yarns (21) arranged on the first plane from the warp yarns (21) arranged on the second plane . In particular, the yarn guide elements (7) have a slightly arched shape so as to punctually raise or lower the warp yarns to facilitate the insertion of the inserted oblique weft yarn (51).

In this embodiment, said thread guide elements (7) are arranged alternately upwards or downwards, so that each pair formed by successive elements forms an "X" in the side views.

The unit (4) for inserting the oblique fixed weft thread (41) comprises a weft-feeding slider (46) which conveniently arranges said thread on the lateral tracks (42, 43) of said group (4). Said weft-feeding slider (46) slides on a guide parallel to the weft already positioned and is fed by a reel placed on cylinders (44, 45) on which it rotates, thus unwinding without causing the yarn to twist.

The lateral tracks (42, 43) drag along the X direction the oblique fixed weft yarn (41) thus arranged, ie directed along the Y direction, which generates a non-right angle with the X direction.

Said lateral tracks (42, 43), which can advantageously be activated independently by means of two distinct actuation units, have, along the external lateral surface, a plurality of projections (421, 431). Around said reliefs (421, 431), which have a substantially cylindrical shape, the oblique fixed weft thread (41) is returned.

Advantageously, the loom is equipped with a plurality of spreaders arranged in proximity to the weaving front F which, by means of an alternating movement coordinated with the passage of the cursor (9), favor the weaving, since they further stabilize the yarn ( 41) with a fixed oblique weft.

Claims (13)

CLAIMS 1. Triaxial fabric frame (1) comprising: a unit (2) for feeding the warp yarns (21) according to one or two planes; a group (3) for advancing the warp yarns (21); a unit (4) for inserting the oblique fixed weft yarn (41) where the latter is oblique with respect to the direction X of feeding the warp yarns; characterized in that it comprises an assembly (5) for inserting the thread (51) of the inserted oblique weft arranged according to an oblique weaving front F both with respect to the direction X of feeding the warp yarns and with respect to the direction Y of insertion of the yarns of fixed oblique weft. 2. Loom as per the preceding claim, characterized in that the advancement of the fixed oblique weft is coordinated with the passage along the weaving front F of the thread (51) of the inserted oblique weft. 3. Loom as per one or more of the preceding claims, characterized in that it comprises a plurality of guiding elements (7) of the warp threads (21), aligned according to said weaving front F and such as to punctually raise or lower the warp threads to facilitate the insertion of the inserted oblique weft thread (51). 4. Loom as per the preceding claim, characterized in that said yarn guide elements (7) consist of static elements suitably shaped to distance the warp yarns (21) arranged on the first plane from the warp yarns (21) arranged on the second plane. 5. Loom as per one or more of the preceding claims, characterized by the fact that each feed plane of the warp yarns is defined by a board (8) suitably shaped so as to vary the direction of the tensions on the warp yarns (21 ) near the guide elements (7). 6. Frame according to one or more of the preceding claims, characterized in that it comprises a plurality of expanders (10). 7. Loom as per the preceding claim, characterized in that said plurality of expanders (10) develops an alternating movement coordinated with the passage along the weaving front F of the inserted oblique weft thread (51). 8. Frame as per one or more of the preceding claims, characterized in that said system (4) for inserting the oblique fixed weft yarn (41) comprises two lateral tracks (42, 43) for dragging said yarn (41) fixed oblique weft. 9. Frame according to the preceding claim characterized in that each of said lateral tracks (42, 43) can be operated independently, in order to obtain compacting effects of the fabric (1). 10. Frame according to one or more of the preceding claims, characterized in that the external lateral surface of each of said lateral tracks (42, 43) has a plurality of reliefs (421, 431), around which the wire is directed (41) of oblique fixed weft. 11. Loom as per one or more of the preceding claims, characterized in that said advancement unit (3) uses the traction action exerted by the winding of the already formed piece of fabric (1). 12. Loom as per one or more of the preceding claims, characterized in that said advancement unit (3) comprises one or more motorized cylinders which facilitate the unrolling or unrolling of said warp yarns (21). 13. Loom as per one or more of the preceding claims, characterized in that said advancement unit (3) comprises one or more motorized cylinders which drive the already formed piece of fabric (1).