TECHNICAL FIELD

The present invention relates to roving mats made from a continuous textured fiber, as well as to a method and a system for manufacturing thereof.

BACKGROUND

Fiber mats are typically made of thin, relatively short fibers by mechanical carding or air blowing. The mats can be shaped by mechanical needling, water bonding, air bonding, or using a binder that binds the individual fibers of the mat.

For example, EP2602370 discloses a method for producing a fiber mat for use as a sound-deadening insert of a silencer of an exhaust-gas discharge system in an internal-combustion engine of a vehicle, wherein the method comprises the steps of - providing a mattress comprising continuous volumized fibers of sound-deadening material, wound around a winding axis and carrying out one or more needling operations on the mattress within, respectively, one or more pre-set surface strips of the mattress itself in such a way as to compact/interweave the continuous fibers locally to obtain, respectively, one or more compacting lines of compacted fibers, each of which extends along said mattress in a direction transverse to the continuous fibers and keeps the continuous fibers joined together locally to prevent the mattress from opening up.

US2009272600 discloses a method of manufacturing a mat, wherein the fibers are interconnected by a needling operation consisting of pointwise intertwining of the fibers.

EP1055760 discloses a method of making a mat wherein the fibers are interconnected by a needling operation where the fibers are entangled together by a set of needles.

Other methods of bonding loose fibers are also known, such as stitching the fibers with an additional thread or welding the fibers together. SUMMARY OF THE INVENTION

There is a need for further modifications of the processes for manufacturing of roving mats, aiming to improve the manufacturing process and enable the mats to be given new properties.

In one aspect, the invention relates to a method for manufacturing a roving mat, the method comprising arranging a strand of texturized and volumized fibers in a shape of the roving mat. The method is carried out as a continuous process that comprises: arranging the strand of fibers on a moving endless conveyor by means of a reciprocating head that moves at an angle of 45 to 90 degrees with respect to the direction of movement of the endless conveyor, thereby forming a continuous strip of directionally aligned fibers, and bonding together at least some of the fibers within the strip to form the roving mat into a form of a continuous web.

In another aspect, the invention relates to a system for manufacturing a roving mat from a continuous strand of textured and volumized fibers, the system comprising a fiber laying unit and a bonding unit for bonding at least some of the fibers together to form a mat of a predetermined shape. The fiber laying unit comprises an endless conveyor and a reciprocating head located over the endless conveyor, wherein the reciprocating head is movable at an angle of 45 to 90 degrees with respect to the direction of movement of the endless conveyor and configured to arrange the strand of fibers on the endless conveyor to form a continuous strip of directionally aligned fibers. The bonding unit is located after the reciprocating head along the direction of movement of the endless conveyor.

In yet another aspect, the invention relates to a roving mat comprising a continuous strand of texturized fibers, wherein at least some of the fibers are bonded together. The roving mat has a form of a continuous web, wherein the strand of fibers is arranged in a zig-zag manner, wherein at the edges of the continuous web the strand changes its direction, such that it is turned around an axis perpendicular with respect to a main plane of the continuous web.

According to the present invention, the method and system allow manufacturing a mat in the form of a continuous web. This is in contrast to the methods known so far, wherein the mat was formed on frames on which the fibers were wound, which required additional work to transfer the packet from the frame to the bonding unit. Furthermore, in the prior art solutions, it is necessary to use frames of different widths to form roving mats of different sizes. In contrast, according to the invention, the width of the mat can be conveniently adjusted by setting the range of reciprocating movement of the head. It is therefore possible to produce the mat in the form of a continuous web, which can be cut to a desired length by the end user, who can form the mats for customized purposes. The density of the mat may also be conveniently designed by changing the speed of the conveyor and the linear weight of the supplied fiber (according to its TEX parameter).

The mat according to the invention, in addition to having the form of a continuous web and the advantages discussed above, comprises strands of fibers turned around an axis perpendicular to the plane of the main web - due to this, the elastic force of the fibers acts on the fibers in a plane which is parallel to the plane of the main web and the fibers at the edges of the mat tend to expand in a direction parallel to the main plane of the web. Consequently, there is no tendency to thicken the mat at its edges; therefore, the main plane of the mat is more planarly uniform than prior art mats.

The mat according to the invention may have various applications, for example as a sound-absorbing element in car mufflers, as a filtering element, or as a material for the construction of composite materials.

The fibers can be of various materials, such as glass fibers (E-glass, ECR-glass, S-glass, S2-glass), polypropylene, polyester, carbon fiber, and basalt fiber.

The strands of fibers are subjected to a process of texturization and volumization. For example, this may include air texturization (to form air-texturized yarn - ATY) or mechanical texturization (as known from the manufacturing of stacked fibers on carding machines (manufacturing of sleeves)).

The continuous web can be wound on a roll or cut into rectangular mats of a predetermined length. Preferably, according to the invention, the system comprises a roll for winding up the mat, which is formed as a continuous web.

The fibers within the strip can be bonded by any known method - mechanical bonding (for example, by stitching or needling), water needling, air bonding, or by means of a binder (organic or inorganic), wherein the fibers can be bonded pointwise or along a line.

At least two layers of fiber strands can be laid on the moving endless conveyor, wherein the first layer is laid using a first head, and the second layer is laid using a second head located after the first head along the direction of conveyor movement. The fiber strand in the first layer can be laid at a first angle relative to the direction of movement of the conveyor, and the fiber strand in the second layer can be laid at a second angle which is equal to or different from the first angle.

The system according to the invention may comprise at least two movable heads, wherein the second head is located after the first head along the direction of movement of the conveyor and is configured to lay the layer of fibers on the layer of fibers laid by the first head. The first head can be movable transversely to the direction of movement of the conveyor at a first angle relative to the direction of movement of the conveyor, and the second head can be movable transversely to the direction of movement of the conveyor at a second angle that is equal to or different from the first angle.

The mat according to the invention may comprise at least two zig-zag-shaped strands of fibers, each of which forms a separate layer. Said at least two strands of fibers may extend at the same or different angles with respect to the longitudinal direction of the web.

Thus, the method and the system make it possible to manufacture layered mats with at least two layers of fibers that may be aligned at different angles, increasing the mat’s total strength. Fibers of different materials, thicknesses, or densities can be used to form the mat as required.

In addition, a layer of additional material supplied from a third feeder can be placed between the first fiber layer and the second fiber layer. Between the first head and the second head, there can be a device for feeding the material from the feeder.

Different materials may be used as the additional middle layer, such as glass nonwovens, needled mats, nets, glass, or synthetic fabrics, which can provide additional properties.

These and other features, aspects, and advantages of the invention will become better understood with reference to the following drawings, descriptions, and claims.

BRIEF DESCRIPTION OF DRAWINGS

Various embodiments are herein described, by way of example only, with reference to the accompanying drawings, wherein:

Fig. 1A shows schematically a system for manufacturing a roving mat made of a continuous textured fiber according to a first embodiment, in a side view, Fig. 1 B shows schematically a fragment of the system according to the first embodiment in a top view,

Fig. 2A shows schematically the system for manufacturing the mat according to a second embodiment, in a side view,

Fig. 2B shows schematically a fragment of the system according to the second embodiment in a top view,

Figs. 3A-3D show examples of end products in a top view.

DETAILED DESCRIPTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense but is made merely to illustrate the general principles of the invention.

First embodiment of a system

Figs. 1A and 1 B show schematically a first embodiment of a system for manufacturing a roving mat from a continuous textured fiber according to the invention, wherein Fig. 1 B shows a fragment of the system between a head 23 and a bonding unit 24 for bonding the fibers.

A strand 11 of fibers subjected to a process of texturizing and volumizing is supplied from a feeder 21 to a reciprocating head 23. The head 23 moves reciprocally (indicated by a horizontal arrow in Fig. 1 B), transversally to the direction of movement (along the vertical arrow in Fig. 1 B) of an endless conveyor 22, which is a belt conveyor. In this way, the strand 11 of fibers is arranged in a zigzag manner, forming a strip 12. At the edges of the strip 12, the strand 11 changes its direction, turning around an axis perpendicular to the main plane of the strip 12. The fibers aligned in successive rows may overlap, but they are not connected to each other, so the strip 12 can retain its shape. The strip 12 is then supplied to a bonding unit 24 that is configured to bond the fibers using a known method, such as a needling unit that forms continuous bond lines as shown in Fig. 3A. The continuous web 13 thus formed is then fed further by a conveyor belt 26 and wound onto a roll 25. Second embodiment of a system

Figs. 2A and 2B show schematically a second embodiment of the system for manufacturing a mat according to the invention, wherein Fig. 2B shows a fragment of the system between a first head 45 and a bonding unit 47.

A first strand 31 of fibers subjected to a process of texturizing and volumizing is supplied from a first feeder 41 to the first head 45. The first head 45 moves reciprocally (indicated in Fig. 2B by an arrow inclined at the angle a1 ), transversally to the direction of movement (along the vertical arrow in Fig. 2B) of an endless conveyor 44, which is a belt conveyor. In this way, the first strand 31 of fibers is arranged in a zig-zag manner to create a strip that forms a first layer 34. From the second feeder 43, a second strand 33 of texturized and volumized fibers is fed to the second head 46, located downstream of the first head 45. The second head 46 moves reciprocally (indicated in Fig. 2B by an arrow inclined at the angle a2), transverse to the direction of movement (along the vertical arrow in Fig. 2B) of the endless conveyor 44. This way, the second strand 33 of fibers is arranged in a zig-zag manner over the first layer 34 to form a second (top) layer 36. Optionally, an additional strip 32 of material, such as nonwoven fabric, may be supplied from a third feeder 42 to be placed between the first layer 34 and the second layer 36 of the zig-zag fiber strands to form a middle layer 35 (wherein the addition of material 32 is not shown in Fig. 1 B for the sake of clarity). The mat thus formed has two zig-zag-shaped strands of fibers aligned at different angles to each other and, optionally a middle layer of additional material therebetween. The multilayer strip is fed to a bonding unit 47 that bonds the strip by a known method, for example, to a needling unit that forms continuous bond lines, as shown in Fig. 3A. The continuous web 37 thus formed is then fed further on a belt conveyor 49 and wound onto a roll 48.

First example of a method

According to this first example, a single-layer mat is formed using the system according to the first embodiment shown in Figs. 1A and 1 B. The strand 11 of fibers can contain fibers having a thickness of 10 microns (wherein it is generally preferred to use 3 to 30 microns, 100TEX to 40000TEX) that have been subject to a texturizing and volumizing process. The head 23 can be moved at 550mm/s, and the endless conveyor 22 can be moved at 800mm/min. A 600mm wide strip can be formed (although strips as wide as 1000mm can also be formed). The fibers of the strip thus formed are then bonded by the bonding unit 24 by needling to form continuous bond lines. A mat with a density of 90 g/l can be produced (whereas, generally, a mat with a density of 50 g/l to 10,000 g/l can be produced).

Second example of a method

According to the second example of the method, a three-layer mat can be formed by the system according to the second embodiment shown in Figs. 2A and 2B. The first strand 31 of texturized and volumized fibers, the second strand 33 of texturized and volumized fibers, and the nonwoven material 32 are supplied. The first head 45 can move with a speed of 500mm/s at an angle a1 equal to 45 degrees, the second head 46 can move with a speed of 500mm/s at an angle a2 equal to -45 degrees, and the endless conveyor 44 can move at a speed of 1 m/min. A strip with a width of 600 mm can be thus formed. The fibers of the strip thus formed are then bonded using the bonding unit 47 by needling to form continuous bond lines. A mat with a density of 100 g/l can be produced (whereas, generally, a mat with a density of 50 g/l to 10,000 g/l can be produced).

Embodiments of the mat

Fig. 3A shows schematically in a top view an outline of a single-layer mat in a form of a continuous web 13 with continuous bond lines 51 extending along the length of the mat. Individual fibers are not shown for clarity.

Fig. 3B shows schematically in top view an outline of a three-layer mat in a form of a continuous web 37 with dashed bond lines 52 extending along the length of the mat.

Fig. 3C shows schematically in a top view an outline of a three-layer mat in a form of a continuous web 37 with dashed bond lines 53 extending diagonally to the longitudinal direction of the mat.

Fig. 3D shows schematically in a top view an outline of a single-layer continuous web 13 with pointwise bonds 54.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications, and other applications of the invention may be made. Therefore, the claimed invention, as recited in the claims that follow is not limited to the embodiments described herein.