The present invention relates to an apparatus and a method for compacting woven and nonwoven fabrics in a planar or tubular configuration.

In the textile industry it is known that due to weaving, bleaching, dyeing and finishing processes fabrics are continuously subjected to stresses that are accumulated inside their fibers and are maintained over time mainly due to friction between the yarns.

Similar problems occur as a result of the manufacturing processes of nonwoven fabrics.

It is known that when a fabric or a finished piece of clothing is washed or is deeply humid, it can easily be deformed and/or shrunk. In fact, the yarns are not dimensionally stable by nature, because they are made of fibers, such as natural fibers, that are deformable both longitudinally and transversely. Water and soap act as a lubricant between the yarns, that thus can move and tend to relax and to return to their original length. This results in a shrinkage of a fabric up to a situation wherein the fibers reach a stable size condition, which causes considerable problems during the various processing steps of a fabric, as well as on finished clothing.

There are several known methods and apparatuses that allow to obtain fabrics having a high degree of dimensional stability, thus minimizing shrinkage and deformation problems.

For instance a controlled compacting method known as "Sanfor" from the name of its inventor is known for many years. The Sanfor method leads to excellent results in terms of dimensional stability of fabrics, in particular of knitted fabrics, shrinkage being lower than 5% in the direction of the weft and warp.

In an apparatus which carries out the Sanfor method a fabric is made to pass through a humidification device supplied with water or steam in order to lubricate the fibers and promote their mobility within the fabric. Generally, the fabric is wetted in such a way as to achieve a water content of about 15% by weight. The fabric is subsequently expanded to a predetermined size by way of a special expansion device and then reaches a portion of the apparatus wherein an endless conveyor belt driven by a motorized roller and supported by a plurality of idle rollers is arranged.

The conveyor belt, typically made of rubber or felt, is squeezed between one of the idle rollers and the motorized roller and is thus stretched proportionally to the applied pressure. The previously wetted fabric is fed into the compression zone by the conveyor belt and is thus pressed therewith in correspondence of the rollers. The fabric is arranged in such a way that the warp yarns are aligned in the feeding direction. Once out of the compression zone the conveyor belt recovers its original size, thereby dragging by friction the fabric arranged thereon. The warp yarns are shortened in the feeding direction, thus bringing the weft yarns closer to each other. After compaction, the fabric is brought into a dryer where the fibers are completely dried and so blocked in their "compacted" condition.

A problem of the apparatuses that carry out the Sanfor compacting method is that the degree of compaction that may be achieved substantially depends on the thickness of the conveyor belt, which is generally comprised between 67 and 70 mm, and on the deformability of the material forming the conveyor belt.

In addition to this, the Sanfor compacting method may be less effective when processing synthetic fabrics, because these are generally more slippery than those made of natural fibers and thus do not easily adhere to the surface of a rubber tape. Highly thick fabrics can also slip in contact with the conveyor belt in their mutual contact portion, thereby reducing the compaction degree, which makes the choice of the material of the conveyor belt, for example an elastomeric material, generally rather difficult.

There are known other methods for compacting fabrics, which employ counter- rotating rollers operated at different angular velocities between which a fabric to be processed is fed.

The international publication WO 2008/052025 discloses an apparatus for the compaction of fabrics comprising a feeding roller and a retarding roller arranged close to the feeding roller, wherein the retarding roller may be rotated in an opposite direction with respect to the feeding roller. The retarding roller rotates at an angular velocity that is lower than the angular velocity of the feeding roller. Between the feeding roller and the retarding roller two mutually opposite blade profiles are arranged. The blade profiles define a transition zone having a calibrated thickness in correspondence of which the fabric in contact with the feeding roller contacts the retarding roller. Since the retarding roller rotates at a lower speed than feeding roller, the fabric slows down at the passage defined by the blade profiles, thus undergoing a compaction in the feeding direction for its whole width.

Similarly to the Sanfor method, the fabric is arranged with the warp yarns aligned in the feeding direction, whereby in the transition area from the feeding roller to the delaying roller compaction is carried out by approaching the weft yarns to one another. In addition to this, as in the Sanfor method also in this case the fabric is subjected to a steam treatment upstream of the feeding roller in order to facilitate sliding of the fibers during the compaction process.

The use of counter-rotating rollers operated at different angular velocities allows to obtain degrees of compaction higher than those obtainable with apparatuses based on the Sanfor method. However, apparatuses employing counter-rotating rollers are affected by a considerable constructive complexity and high costs.

Patent US 2262268 discloses a compacting apparatus wherein after a steaming treatment a fabric to be compacted is received between two conveyor belts supported by a plurality of motorized rollers. The motorized rollers arranged at an inlet and an outlet of a path between the conveyor belts are operated at different angular velocities, which determines a tangential speed of the conveyor belts that is slower and slower in a feeding direction of the fabric. Consequently, the velocity of the fabric between the conveyor belts at the inlet is higher than its velocity at the outlet, thereby causing compaction of fabric fibers.

The existence of several technical solutions for compacting fabrics notwithstanding, a need for improved solutions is still felt, in particular the need to improve the control accuracy of the compaction degree without penalizing manufacturing costs, which is an object of the present invention. Said object is achieved with a compacting apparatus and method whose main features are specified in claims 1 and 11 , respectively, while other features are specified in the remaining claims.

An idea of solution underlying the invention is to make a compacting apparatus provided with at least one pair of compacting units provided with respective conveyor belts and to arrange such compacting units so that their respective conveyor belts face each other and a compacting slit suitable to allow passage of a fabric by dragging is defined between them. The fabric is fed from an inlet to an outlet of the compacting slit of in a longitudinal direction and the moving velocity of the fabric is temporarily increased and subsequently decreased in a portion of the slit which extends between an intermediate position thereof and its outlet.

The local variation of the moving velocity causes a compaction of the fibers at the outlet of the slit.

Compaction is carried out in an extremely precise way by moving the conveyor belts of the compacting units by way of respective chains having an extensible/retractable structure. These chains are supported by respective sets of rollers comprising a pair of motorized rollers arranged consecutively to each other at an intermediate position and at the outlet of the slit. The motorized rollers are operated such that the angular velocity of the roller that precedes in the feeding direction of the fabric, i.e. the compacting direction, is higher than the angular velocity of the roller that follows, which is arranged at the outlet of the slit.

The invention also advantageously provides a step of adjusting the position of a toothed redirecting roller of the sets of rollers which respectively support the chains of the compacting units. By changing the position of the redirecting roller it is possible to compensate for the different lengths the extended/shortened chain has in the portion between the inlet and the outlet of the slit, thereby making it possible to calculate and adjust precisely and accurately the difference between the angular velocities of the consecutive motorized rollers on the basis of the desired compaction degree.

The operation of the compacting units is advantageously controlled automatically by a control system and adjustments of the difference between the angular velocities of the motorized roller that precedes and of the motorized roller that follows of the pair of motorized rollers which carry out compaction of the fabric takes place simultaneously and in a synchronized manner in the two compacting units.

Another advantage offered by the invention is that compaction of the fabrics is carried out by way of a compression process that is purely mechanical and does not require the aid of humidification means, drying means and the like, which allows to achieve treatment velocities higher than those which characterize apparatuses based on the Sanfor method and other compacting apparatuses known in the field.

Further advantages and features of the compacting apparatus and method according to the present invention will become clear to those skilled in the art from the following detailed and non-limiting description of two embodiments thereof with reference to the accompanying drawings wherein:

- Figure 1 is a partially sectional, side view schematically showing a compacting apparatus according to the invention;

- Figures 2a and 2b are a top plan view and a side view, respectively, showing a portion of the dragging chain in a configuration of maximum extension;

- Figures 2c and 2d are a top plan view and side view, respectively, showing a portion of the dragging chain in a configuration of minimum extension;

- Figure 3 is a partially sectional, side view diagrammatically showing the conveyor belt and the dragging chain of a compacting unit of the apparatus of Figure 1 ;

- Figure 4 shows a detail IV of Figure 3.

Referring to Figure 1, a compacting apparatus according to the invention is generally indicated by reference numeral 100 and comprises two compacting units 200, 300 arranged in a mirror fashion with respect to a longitudinal direction L, which represents the direction along which a fabric F to be processed is moved throughout the apparatus 100. The path of the fabric F is schematically indicated by a dashed line.

The compacting units 200, 300 are spaced apart in a vertical direction V perpendicular to the longitudinal direction L and define between them a compacting slit 400 through which a fabric F to be processed is received and made to pass. In an operative condition of the apparatus 100, the fabric F is fed in the longitudinal direction L from an inlet 401 to an outlet 402 of the slit 400 undergoing a compaction process as it will be described in detail hereinafter.

The height of the slit 400 is adjusted according to the thickness of the fabric F to be processed and for this purpose the apparatus 100 comprises suitable linear actuators restrained between frames 201, 301 of the compacting units 200, 300. In the embodiment shown in Figure 1, two linear actuators 101, 102 mounted on the frame 201 of the compacting unit 200 are e.g. shown, the actuators being respectively restrained to the frame 301 of the compacting unit 300.

In order to allow passage of a fabric F through the slit 400, each compacting unit 200, 300 comprises a conveyor belt 210, 310 supported by a plurality of rollers which together define an endless closed path. The conveyor belt 210, 310 of each compacting unit 200, 300 is made of a compressible material in the longitudinal direction, such as e.g. rubber or felt, or may be formed by an air chamber. Depending on the type of woven or nonwoven fabric to be treated combinations of conveyor belts made of different materials may be foreseen.

The closed endless paths have respective flat portions between the inlet 401 and the outlet 402 of the slit 400 and respective diverging portions beyond the outlet 402, which allow to release a processed fabric F so that it may be collected from the apparatus 100 or proceed to further treatment units.

As shown by the arrows in the figure, the conveyor belts 210, 310 circulate along their respective endless paths in opposite rotation directions, thus allowing to drag a fabric to be treated along the slit 400 from the inlet 401 to the outlet 402.

According to the invention, the conveyor belts 210, 310 are dragged by respective chains 220, 320 of the compacting units 200, 300 arranged beneath them, that mate the faces of the conveyor belts opposite to the face intended to contact a fabric F to be treated.

As shown in Figure 1, similarly to the conveyor belts 210, 310, the chains 220,

320 are supported by a plurality of rollers, some of which are motorized rollers and others are idle rollers, forming a closed endless path which overlaps at least partially with the path of the conveyor belts 210, 310. In the illustrated embodiment the rollers that support the chains are also supporting rollers of the conveyor belts, as it will be described in greater detail hereinafter.

As shown in the illustrated embodiment, the overlapping portion between the two closed endless paths is at least the flat portion of the slit 400 comprised between the inlet 401 and the outlet 402. Preferably, the overlapping portion between the endless paths of the conveyor belts 210, 310 and chains 220, 320 also comprises a part of the diverging portions beyond the outlet 402.

Each chain comprises a plurality of pivots arranged parallel to each other in the longitudinal direction L, and a plurality of links assembled on the pivots and arranged parallel to each other in a transverse direction T perpendicular to the longitudinal direction L and to the vertical direction V. The links are restrained to the pivots in the transverse direction T by known means, for example by way of cotter pins located at the ends of the pivots.

The chains can be made of metal, plastic or composite materials and combinations thereof.

Figures 2a to 2d show in particular the chain 220 of the compacting unit 200, the axes of which are indicated with reference number 221 and whose links are indicated with reference numbers 222.

The links of the chains 220, 320 comprise gripping surfaces (not shown), for example knurled, intended to mate the respective conveyor belt 210, 310 in order to allow dragging.

As shown in Figures 2b and 2d of the links of the chains 220, 320 comprise a hole at one of its ends wherein a pivot is fitted and at the opposite end a slot wherein the pivot of a link consecutive is slidably fitted. This configuration provides the chains 220, 320 with a variable length depending on the position of the pivots in the slots of the respective links.

By varying the angular velocities of two motorized rollers arranged consecutively, it is therefore possible to cause localized changes of the length of the chains, particularly a localized shortening of the chains in the longitudinal direction L, which is exploited in the straight portions of the endless paths of the conveyor belts in order to compact the fabric in the longitudinal direction L.

For simplicity's sake, only the compacting unit 200 will be described in detail hereinafter, the compacting unit 300 being completely identical thereto as far as the object of the invention is concerned.

Still with reference to Figures 2a to 2d, 3 and 3a, the chain 220 is supported by a set of rollers some of which are motorized rollers and others are idle rollers.

In the embodiment shown in Figure 3 seven rollers are e.g. shown, three of which are indicated with reference numbers 231, 232 and 233 and are aligned in the longitudinal direction L between the inlet 401 and the outlet 402 of the compacting slit 400, while the other four are indicated with reference numbers 234, 235, 236 and 237 and are arranged so as to define with the first three rollers an endless path which allows recirculation of the chain 220.

The motorized rollers are e.g. roller 232, roller 236 and roller 233. The first two rollers 232 and 236 are provided with teeth adapted to engage the pivots 221 of the chain 220, while roller 233 has a smooth surface covered with a friction material.

Rollers 234 and 235 are redirecting idle rollers with smooth surfaces. A tensioning device, such as e.g. a hydraulic jack, is preferably associated with one of these rollers, roller 235 in particular.

Rollers 237 and 231 are redirecting idle rollers too, but, unlike rollers 234 and

235, they have teeth adapted to engage the pivots of the chain 220 for reasons that will be explained hereinafter.

As mentioned above, in order to carry out compaction of a fabric in the longitudinal direction L, two consecutive rollers that are respectively arranged at an intermediate position of the slit 400 and at its outlet 402 are operated at different angular velocities.

With reference to the illustrated embodiment, these consecutive rollers are for example roller 232 and roller 233. Roller 232, which precedes, is operated at an angular velocity co ₂ higher than the angular velocity co ₃ of the roller 233 that follows, the latter determining proportionally to its diameter the nominal velocity or line velocity of the conveyor belt 210, whereby the pivots 221 that progressively come in the portion of the chain 220 comprised between the two rollers are subjected to an acceleration towards roller 233 and slow down at this roller thus returning to the nominal moving velocity as determined by its angular velocity ω ₃ and its diameter. Since the links 222 of the chain 220 have slots, this localized variation of the moving velocity causes the pivots 221 of the chain 220 to approach each other thereby dragging the links 222, which results in a progressive thickening of the chain structure.

Consequently, the portion of the conveyor belt 210 which contacts the chain 220 in the portion comprised between the rollers 232 and 233 is compacted in the longitudinal direction L together with the fabric carried thereon.

Operation of the compacting unit 300 is exactly the same as the compacting unit 200 and the two units 200, 300 are controlled such that a fabric F which travels through the slit 400 is simultaneously subjected to the compacting action described above on its two faces.

The rubber coating and the absence of teeth of roller 233 contribute to the braking action it performs so as to allow to bring the pivots 221 of the chain 220 closer to each other, which are accelerated in the longitudinal direction L from the roller 232 that precedes.

Along the redirecting path on rollers 234, 235 the chain 220 with the pivots 221 so brought closer to each other proceeds at the nominal moving speed towards the motorized roller 236, which is made to rotate at the same angular velocity of the roller 233 and whose teeth engage the pivots 221.

The chain 220 then proceeds at a constant velocity toward the motorized roller

232 passing on the idle redirecting rollers 237 and 231, which have teeth like rollers 232 and 236.

The motorized rollers 233 and 236, which operate at the same angular velocity o ₃ as explained above, may advantageously be restrained to one another for example by way of a transmission belt, as shown in the illustrated embodiment. The motorized roller is the toothed roller 236 and roller 233 is thus a driven roller. In this way, the structure of the compacting unit 200 is simplified and cheaper, thus ensuring in simple and cost effective manner maintenance of the nominal moving velocity of the chain 220.

In order to allow approaching of the chain pivots 221 between the consecutive motorized rollers 232, 233 it is necessary that the chain 220 can be shortened when it reaches the motorized roller 232, which is driven at a higher angular velocity, namely that the links 222 have the possibility to move relative to the pivots 221. As explained above, it will be appreciated that shortening degree of the chain, and hence the compaction degree of a treated fabric, depends on the position of the pivots 221 within the slots of the links 222.

This position can be adjusted by varying the length of the path of the chain 220 between the motorized toothed roller 236, which determines the moving nominal or line velocity, and the motorized roller 232, which accelerates the links 222 towards roller

233 that rotates the same angular velocity of roller 236. To this aim, one of the redirecting rollers arranged between the motorized toothed roller 236, which is operated at the nominal angular velocity, and the motorized roller 232, which is operated at a higher angular velocity, is movable relative to the other rollers of the set of rollers by way of a linear actuator 240. In the illustrated embodiment the movable roller is in particular the idle toothed roller 237.

In a configuration wherein the endless closed path has a maximum length, the chain 220 is fully extended as shown in Figures 2a and 2b, and the pivots 221 are located in an end stroke position in their respective slots of the links 222. Therefore, they cannot be moved in the longitudinal direction L and in this configuration no compaction of a treated fabric may be carried out.

On the contrary, in a configuration wherein the endless closed path has a minimum length, such as the configuration shown in Figures 2c and 2d, the pivots 221 of the chain 220 may travel the whole distance along their respective slots of the links 222, thus allowing to obtain the maximum possible level of compaction of the treated fabric.

Intermediate lengths of the endless closed path of the chain 220 define intermediate compaction degrees of the treated fabric. Figure 3 schematically shows in dotted lines a possible intermediate position of the idle roller 237 and the resulting arrangement of the portions of the chain 220.

The provision of toothed rollers in the redirecting path of the chain and the position of the toothed roller 237 relative to the other toothed rollers of the set of rollers allow to define the extension degree of the chain 220 geometrically precisely and thus the compaction degree that may be achieved, based on which the angular velocity difference between the accelerating roller 232 and roller 233, driven at the angular velocity that determines the nominal movement velocity of the conveyor belt 210, is established.

In the embodiment of the invention shown in the figures, the closed endless path of the conveyor belt 210 is wider than that of the chain 220 which moves it, and to this aim it comprises a plurality of idle redirecting rollers 211, 212, 213, at least one of which, for example roller 212, is associated with a tensioning device. Such a device can for example comprise a tiltable arm restrained to a hydraulic actuator in correspondence to its free end.

This configuration of the compacting unit 220 is preferred because it allows to obtain an extension of the fabric path beyond the outlet 402 of the compacting slit 400, which facilitates collection of the fabric and/or its prosecution to further treatment units.

According to a further aspect of the invention, depending on the desired degree of compaction, the apparatus 100 may comprise two or more pairs of compacting units, altogether similar to the units 200, 300 described above and arranged in series.

Moreover, the pair or pairs of compacting units may be arranged in free environment such as inside an industrial building, or housed in heated tunnel structures supplied with steam or configured for spraying water or impregnating additives.

Humidification and/or impregnation units may also be associated with the individual compacting units close to or in correspondence with the inlet 401 of the compacting slit.

Depending on of the fabric, more in general of the material, to be treated it is possible to combine the compacting method according to the invention with special environmental conditions that can influence the final compaction degree.

The present invention has hereto been disclosed with reference to preferred embodiments thereof. It is to be understood that there may be other embodiments relating to the same inventive idea, as defined by the scope of protection of the claims set out below.