EP3754088A1

EP3754088A1 - Apparatus for compacting a continuous textile substrate by means of elastic belt

Info

Publication number: EP3754088A1
Application number: EP20179933.5A
Authority: EP
Inventors: Giulio MANDRUZZATO; Andrea NICOLETTI
Original assignee: Santex Rimar Group SRL
Current assignee: Santex Rimar Group SRL
Priority date: 2019-06-17
Filing date: 2020-06-15
Publication date: 2020-12-23
Anticipated expiration: 2040-06-15
Also published as: JP2020204138A; MX2020006381A; CN112095268A; MA53678A; IT201900009198A1; EA039952B1; EP3754088B1; EA202091249A1

Abstract

The invention relates to an apparatus for compacting a continuous textile substrate (T) by means of elastic belt, comprising: - a heatable rotating cylinder (10); - an endless belt (20) movable along a closed path (P) to support and transport the textile substrate (T) in contact with a side surface portion (11) of said heatable rotating cylinder (10), said belt being elastically deformable in elongation; - a roller system (31, 32, 33, 34, 35) on which said belt (20) is wound in a state of pretensioning in elongation, wherein said roller system comprises a plurality of idle return rollers (33, 34, 35) and a plurality of motorized rollers (31, 32) which may be operated so as to slide said belt (20) along said closed path (PC), imposing on said belt an additional tensional state of elongation at a first section (T1) of said path which extends - with respect to a direction of advancement (X) of the belt - upstream of a second section (T2) of said path in which said belt (20) is kept in contact with the rotating cylinder; means (40) for guiding said textile substrate (T) between said belt (20) and said heatable cylinder (10) along said second section (T2) of said path. The apparatus comprises a system for reducing friction coefficient between the belt (20) and the heatable rotating cylinder (10), said system for reducing friction coefficient comprising one or more interposition tapes (61, 62; 63) between belt and cylinder.

Description

Field of application

The present invention relates to an apparatus for compacting a continuous textile substrate by means of elastic belt.

Prior art

As is known, the compacting process of fabrics or textile substrates is one of the main processes in the field of textile finishing and has the purpose of giving stability to the fabrics before going to the manufacturing step.
Usually the stability and compaction of the fabric is imparted with machinery with consolidated technology which use a change in the curvature of a felt or rubber belt on which the fabric on which to impart the compaction is placed. The change of curvature of the support (felt or rubber belt) then imparts a longitudinal retraction to the fabric which is then pressed against a hot cylinder, which stabilizes the compacting effect ensuring the dimensional stability of the fabric once it leaves the machine.
All fabrics (whether orthogonal or knitted), after being produced, require a stabilization and compaction process which makes them suitable for being cut for sewing. Compacting machines are therefore used extensively in finishing processes. The compaction values obtainable depend on the degree of initial stability of the fabric produced. The degree of initial stability of a fabric in turn depends on the type of material it is made of.
Frequently, it is necessary to carry out several passes of the same fabric through compacting machines in order to obtain the desired compaction result. This is particularly the case if the fabric originally had a high degree of instability. All of this lengthens treatment times and affects production costs.
The need to reduce the times of fabric compaction processes is therefore very felt in the sector, especially in the case of fabrics (for example made of viscose) which are characterized by high degrees of initial instability.
Over time, different alternative technical solutions have been proposed, which aimed to make compaction systems more efficient. However, these solutions have proved to be not completely satisfactory.
In more detail, the compacting (or shrinking) treatment of fabrics is carried out essentially by means of a so-called "compression" technique which is based on the use of a substantially deformable belt, to which the fabric to be compacted is tightly coupled. The deformation of the belt in the longitudinal direction of advancement, by means of mechanical means suitable for the purpose, substantially consists of the succession of a first expansion step and a second contraction step. The fabric, engaged integrally with the deformable surface of the belt, undergoes, in particular during the contraction step, a "compression" in the direction of advancement, that is, a compaction of its structure and, ultimately, a longitudinal shrinking.
The deformability of the belt may be determined by the type and features of the material of which it is made and also by the type of mechanical stress exerted thereon by the mechanical means adapted to deform it. Thus, deformations by pressing of the belt are known which cause the expansion (elongation) thereof followed by a contraction (shortening) to the initial relaxed state; or deformations by variation of peripheral speed of the belt obtained by sliding it on rollers or cylinders with different radius of curvature with an alternately convex and concave path which alternately cause an increase (lengthening) and a decrease (shortening) of peripheral speed; or, finally, deformations by longitudinal traction of the belt (elongation) followed by a release of the traction (shortening) to the initial relaxed state.
GB patent 563 638 describes an apparatus for compacting fabrics which aims to improve the prior art by using an endless elastic belt supported and guided by rollers, one of which rotates at a variable speed and higher than the roller that precedes it. In this way, the portion of the belt comprised between said two rollers is placed in an elongated state, while in the following section, as tension is relaxed, the belt undergoes a longitudinal contraction equal to the previous elongation. The fabric, coupled to the belt at the elongated portion thereof, follows it in the subsequent relaxed portion, in partial winding around a rotating and heated cylinder, also undergoing a corresponding longitudinal contraction or shrinkage.
This technique, however, is not free from drawbacks, the first of which concerns the fact that the elastic belt is rotated between the guide rollers in a completely and naturally relaxed state. Consequently, in the tension release section, subsequent to that in which the longitudinal traction that causes the elongation thereof is applied, the belt returns completely to its naturally relaxed state, without maintaining any minimum residual tension that allows it to transport and effectively guide the fabric during the shrinking step and not even offer any control of its own path around its guide rollers.
A further negative aspect is linked to the fact that the elastic belt, which is therefore extendable in length, subjected to longitudinal traction also deforms transversely with a consequent and uncontrollable decrease in width. When the tensile stress ceases, both dimensions of the belt tend to regain the original size, that is to say, it re-widens and since, as mentioned, it has not maintained any minimum residual tension, its surface tends to flow loosely and not outstretched, transmitting such irregularities to the fabric coupled thereto.
The technical solution proposed in European patent application EP1657340A1 overcomes the drawbacks described above.
More in detail, this solution provides for a pre-tensioning traction to be applied to the elastic belt in such a way that it maintains a minimum residual tension at the end of the release step of the traction which caused the elongation thereof.
More in detail, the fabric compaction apparatus described in EP1657340A1 comprises a heated rotating cylinder around which an elastic belt is partially wound. The elastic belt is moved by a plurality of motorized rollers and idle return rollers according to a predefined closed path.
The roller apparatus is configured in such a way that by operating on the relative position of one of the idle rollers it is possible - during assembly of the belt on the rollers - to pre-tension the belt itself with respect to its relaxed state. During operation of the apparatus, with respect to this basic state of pre-tensioning, the elastic belt is further stretched by elongation before coming into contact with the cylinder. When the belt comes into contact with the fabric in the winding section around the cylinder, the belt is free to contract longitudinally, thereby dragging the fabric with it in a relative movement with respect to the cylinder. In this way, the fabric is dragged by the longitudinal contraction movement of the elastic belt and is thus compacted longitudinally.
The compaction apparatus described above allows the compaction process to be improved by virtue of the belt pre-tensioning, but the results obtained are however not completely satisfactory.
The owner of the present patent application has been able to note, in particular, that the compaction of the textile substrate is disturbed by tensions induced on the belt in a non-homogeneous way by the direct contact between the belt and the heated cylinder.
More in detail, in the compaction apparatus the contact area (direct or indirect) between the hot cylinder and the elastic belt is an area of high instability because at it the elastic deformability features of the belt meet the rigidity of the hot cylinder steel surface.
As already mentioned, in this area of the compaction apparatus the elastic belt exerts its compacting action on the textile substrate transmitting to the substrate its own contraction and return movement to the original (pretensioned) length.
In this area of the apparatus, the elastic belt slides on the surface of the hot cylinder because the belt and the hot cylinder, although moving in the same direction, could never have identical speeds.
In fact, it should be noted that the shortening effect of the elastic belt due to the relaxation of the tension generates an apparent negative speed resulting in a slowing down effect of the belt with respect to the hot cylinder.
This effect adds to the slowing down of the belt caused by the frictions generated by the direct contact between the belt and the cylinder.
In more detail, the heated cylinder and the elastic belt are sized in such a way that their height is greater than the heights of the textile substrates which are normally subjected to compaction. Therefore, during use it is unavoidable that the elastic belt comes into direct contact with the heated cylinder at two strips located laterally to the textile substrate which slides interposed between the elastic belt and the cylinder.
At these two side strips, due to the high coefficient of friction between the material of the elastic belt and the metal of the cylinder, sliding and friction occur which oppose the relaxation of the belt, thereby locally raising the temperature. This localized braking effect on the side strips also tends to deform the belt differently than the central strip in which, on the other hand, the elastic belt does not come into direct contact with the side surface of the heated cylinder due to the presence of the textile substrate being treated. In the central strip, in fact, the latter slides directly on the cylinder by virtue of a low friction coefficient.
Such localized deformations create tension on the whole belt and disturb the shrinkage thereof. This adversely affects the compaction of the textile substrate being treated, which therefore loses efficiency.
Furthermore, the non-homogeneous sliding of the belt generates waves along the height extension of the belt itself. These waves, in addition to mechanically stressing the belt, reducing its operating life, are transmitted to the textile substrate being treated, causing undesired creases and tensions therein.
Finally, over time the thermal stresses caused by slipping and friction contribute to an early wear of the elastic belt, with a consequent reduction in its operating life.
The owner of the present patent application has therefore found that the phenomena described above negatively affect the efficiency of the compaction process.
The present invention therefore aims to address the problems linked to these phenomena, meeting a general need in the sector, that is to make the compaction of the textile substrate more efficient, possibly also increasing the operating life of the elastic belt.

Disclosure of the invention

Therefore, the object of the present invention is to eliminate in whole or in part the drawbacks of the prior art cited above, by providing an apparatus for compacting textile substrates by means of elastic belt which allows the compaction of the textile substrate to be made more efficient and the operating life of the elastic belt to be increased.
A further object of the present invention is to provide an apparatus for compacting fabrics by means of elastic belt which allows the stresses imposed on the elastic belt to be reduced during the contraction step in contact with the heatable cylinder.
A further object of the present invention is to provide an apparatus for compacting fabrics by means of elastic belt which is simple and cost-effective to manufacture.
A further object of the present invention is to provide an apparatus for compacting fabrics by means of elastic belt which may be managed in an operationally simple manner.

Brief description of the drawings

The technical features of the invention, according to the aforesaid aims, may clearly be seen in the content of the claims below, and its advantages will become more readily apparent in the detailed description that follows, made with reference to the accompanying drawings, which illustrate one or more purely exemplary and non-limiting embodiments thereof, in which:

Figure 1 shows a schematic side view of an apparatus for compacting textile substrates by means of elastic belt according to a first embodiment of the present invention;
Figure 2 shows an enlarged view of a detail of the diagram of Figure 1 relating to the compaction zone of the textile substrate, in which the elastic belt partially wraps the heated cylinder;
Figure 3 shows a perspective top view of the portion of the compacting apparatus illustrated in Figure 2;
Figure 4 shows an orthogonal side view of the portion of the compacting apparatus illustrated in Figure 2 according to the arrow IV shown therein;
Figure 5 shows a schematic side view of an apparatus for compacting textile substrates by means of elastic belt according to an alternative embodiment of the present invention;
Figure 6 shows an enlarged view of a detail of the diagram of Figure 5 relating to the compaction zone of the textile substrate, in which the elastic belt partially wraps the heated cylinder;
Figure 7 shows a perspective top view of the portion of the compacting apparatus illustrated in Figure 6;
Figure 8 shows an orthogonal side view of the portion of the compacting apparatus illustrated in Figure 6 according to the arrow VIII shown therein.

Detailed description

With reference to the accompanying drawings, reference numeral 1 indicates as a whole an apparatus for compacting a continuous textile substrate by means of an elastic belt according to the invention.
Advantageously, the textile substrate T may be of any type; in particular it may be an orthogonal (shuttle) fabric or a knitted fabric. The textile substrate may be formed by any type of fiber used for shuttle and knitted fabrics.
As schematically illustrated in Figures 1 and 4, the compacting apparatus 1 comprises:

a heatable rotating cylinder 10;
an endless belt 20 which is elastically deformable in elongation and is movable along a closed path to support and transport a textile substrate T in contact with a side surface portion 10a of said heatable rotating cylinder 10;
a roller system 31, 32, 33, 34, 35 on which the belt 20 is wound in an elongation pre-tensioning state.

In turn, such a roller system comprises a plurality of idle return rollers 33, 34, 35 and a plurality of motorized rollers 31, 32.
The motorized rollers 31, 32 may be operated so as to make the belt 20 slide along the aforementioned closed path, imposing an additional tensional state of elongation on the belt with respect to the pretensioning one at a first section T1 of said path which extends - with respect to a direction of advancement X of the belt - upstream of a second section T2 of such a path in which said belt 20 is kept in contact with the rotating cylinder.
The compacting apparatus 1 further comprises means 40 for guiding a textile substrate T between the belt 20 and the heatable cylinder 10 along the second section T2 of such a closed path.
Operationally, the compacting action on the textile substrate T takes place along the aforementioned second section T2 of the closed path. At such a second section T2, the elastic belt contracts elastically, passing from the additional tensional state of elongation, which was imposed thereon upstream in the first section T1, to a state close to that of pretensioning. The textile substrate T, which in the second section T2, by virtue of the frictional forces, moves integrally with the belt 20, undergoes the contraction of the belt itself, and in turn contracts longitudinally, compacting itself.
As illustrated in the accompanying figures, the compacting apparatus 1 comprises a system for reducing the friction coefficient between the belt 20 and the heatable rotating cylinder 10.
Such a friction reduction system in turn comprises one or more interposition tapes 61, 62 or 63 which are guided in partial winding around the cylinder 10 and in direct contact with its side surface 10a to interpose itself/themselves between the belt 20 and the side surface 10a of the cylinder 10 along the aforesaid second section T2 of the closed path of the belt.
The interposition between belt and cylinder of such one or more interposition tapes 61, 62 or 63 takes place at least at two axial end strips 11, 12 of the side surface 10a of the cylinder 10 which are in axially opposite positions with respect to the axis of rotation Y of the cylinder itself.
Said one or more interposition tape 61, 62 or 63 are made of a material that is suitable to generate with the side surface of the cylinder 10 a friction coefficient lower than that generated with the belt 20.
Operationally, the friction coefficient reduction system intervenes, therefore, at least at the two axial end tapes of the side surface 10a of the cylinder 10 which in use are generally left uncovered by the textile substrate T being treated.
In other words, the friction coefficient reduction system is configured to avoid direct contact between elastic belt 20 and side surface 10a of cylinder 10.
Operationally, the invention exploits the physical phenomena related to the friction between different materials: elastic belt material; interposition tape material; metal of the heatable cylinder.
Between elastic belt and textile material, frictional forces are generated that are higher than those generated between textile material and the metal surface of the heatable cylinder.
Preferably, the interposition tapes are made of a material which generates the lowest possible frictional forces with the metal surface of the cylinder.
It follows that the aforementioned one or more interposition tapes tend to move integrally with the elastic belt and follow its contraction movements, while said one or more tapes tend to slide freely on the metal surface of the cylinder. The interposition tapes therefore act as a sort of solid lubricant.
In this way, at the aforementioned axial end strips of the cylinder - due to the interposition of said one or more tapes between the belt and the cylinder - operating conditions similar to those which are in use in the central strip occupied by the textile substrate T being treated, which is interposed between the belt and the cylinder, are substantially recreated.
This creates a homogeneous friction reduction system between belt and cylinder, with beneficial effects in terms of:

reduction of the heat generated on the elastic belt;
reduction of the mechanical stresses on the elastic belt generated by localized tensions due to different sliding speeds on the cylinder of the different portions of the belt itself;
reduction of the disturbing phenomena of the contraction/shrinking movements of the elastic belt. Consequently, thanks to the invention we have:
increase in the operating life of the elastic belt; and
greater efficiency of the compaction process.

A further advantage over prior art solutions lies in the fact that the heatable cylinder 10 no longer requires particular and expensive surface treatments to reduce the friction coefficient with the belt 20, but a normal surface treatment is sufficient to obtain a roughness compatible with the material of the interposition tapes to obtain reduced friction coefficients. This may be achieved with low cost surface coatings, obtained for example by nitriding, chrome plating, deep/strong chrome plating.
Preferably, the side surface 10a of the cylinder 10 has a roughness Ra of between 10 microns and 40 microns.
In other words, unlike prior art solutions, the roughness of the side surface 10a of cylinder 10 is no longer a fundamental parameter, since direct contact between belt 10 and cylinder 20 is no longer provided.
Advantageously, due to the fact that said one or more interposition tapes slide without friction on the side surface of the cylinder, remaining integral with the elastic belt, they are substantially not subject to significant sliding phenomena, nor to significant overheating phenomena. The operating life of these tapes is therefore high. This leads to reduced operational maintenance needs.
Preferably, said one or more interposition tapes 61, 62 or 63 are made of fabric or non-woven fabric.
In this way, the interposition tapes have mechanical features comparable to those of the textile substrates T which are treated by the compacting apparatus 1.
In particular, the choice of a fabric or a non-woven fabric makes the interposition tapes more capable of following the contraction movements of the belt 20, due to intrinsic deformability properties. The risk that the interposing tapes may disturb the movements of the belt 20 is therefore reduced.
According to a first embodiment, said one or more interposition tapes may be made of a fabric of natural textile fibers, preferably selected from the group consisting of cotton, wool, cellulose.
According to an alternative embodiment, said one or more interposition tapes are made of a fabric or a non-woven fabric of synthetic fibers, preferably selected from the group consisting of polyester and nylon.
Said one or more interposition tapes may be made of a mixed fabric of natural fibers and synthetic fibers.
According to a particularly preferred embodiment, the aforementioned fabric or non-woven fabric comprises elastomeric fibers. Preferably, the aforementioned one or more interposition tapes are made of a fabric defined by a mixture of polyester-elastane and/or nylon-elastane fibers.
Preferably, said fabric or said non-woven fabric has a basis weight of not less than 50g/m2. In fact, it has been found that there are improvement effects in terms of increasing compaction efficiency compared to the use of fabrics or non-woven fabrics with weights lower than 50 g/m2.
According to an embodiment not shown in the accompanying drawings, the compacting apparatus 1 comprises means for wetting with an aqueous solution, preferably only water, said one or more interposition tapes 61, 62 or 63.
Preferably, the wetting of the interposition tapes is provided in the case in which such tapes are made of woven fabric or non-woven fabric. It has been found that the wetting of the tapes facilitates their sliding on the surface of the cylinder and has beneficial effects on the compaction process of the textile substrate T to be treated.
According to a preferred embodiment, illustrated in Figures 5 to 8, the aforementioned friction coefficient reduction system comprises two distinct interposition tapes 61, 62.
As may be seen in particular in Figures 7 and 8, these two distinct tapes 61 and 62 are guided in partial winding around the cylinder 10 and in direct contact with its side surface to interpose itself between the belt 20 and the side surface 10a of the cylinder 10 along the aforesaid second section T2 of the closed path of the belt.
More in detail, a first interposition tape 61 is guided at a first axial end strip 11 of the side surface 10a of the cylinder 10 and a second interposition tape 62 is guided at a second axial end strip 12 of the side surface 10a of the cylinder 10.
These two interposition tapes 61, 62 leave uncovered a central strip 13 of the side surface 10a of the cylinder 10 to allow in use a textile substrate T to be treated to slide in direct contact with the cylinder 10.
Preferably, the axial winding position of both or at least one of said two interposition tapes 61, 62 around the cylinder 10 is adjustable so as to vary the width in the axial direction (height) of the uncovered central strip 13.
This adjustment of the axial position is made as a function of the height H of the textile substrate T to be treated.
Preferably, since the compacting apparatus 1 may have to treat textile substrates T having different heights H, during the design step the interposition tapes are dimensioned in terms of height H1 and H2 with the maximum hypothetical value according to the minimum height Hmin that the textile substrate may have.
More in detail, the two tapes 61 and 62 should have a total height H1 + H2 as a whole such as to cover the two end strips 11 and 12, in case the apparatus 1 processes a textile substrate with a minimum height Hmin. In other words, if the axial extension of the belt 10 is equal to Hn (it could be equal to or less than the axial extension of the cylinder Hc), (H1 + H2 + Hmin) should be equal to or greater than Hn.
In other words, the heights H1 and H2 of the two tapes 61 and 62 should be sized so that the two end strips 11 and 12 left uncovered by the textile substrate T may always be covered by the two interposition tapes 61 and 62.
Operatively, it is allowed that the interposition tapes 61 and 62 may axially protrude with respect to the belt 20 or to the cylinder 10.
According to an alternative embodiment, illustrated in Figures 1 to 4, the aforementioned friction coefficient reduction system may comprise a single interposition tape 63 which is guided in partial winding around the cylinder 10 and in direct contact with its side surface 10a for interposing itself between the belt 20 and the side surface of the cylinder 10 along said second section T2 of the closed path of the belt.
As may be seen in particular in Figures 3 and 4, said single interposition tape 63 has an axial extension H3 at least equal to the axial extension Hn of said belt 20.
In use, said single interposition tape 63 therefore interposes also between the textile substrate T to be treated and the side surface 10a of the cylinder 10.
In this case, the textile substrate T to be treated does not come into contact with the cylinder 10, but with the interposition tape 63.
Due to the friction that forms between the textile substrate T and the interposition tape 63 (in particular when it is made of woven fabric or non-woven fabric), the interposition tape 63 will tend to follow the textile substrate T integrally and to slide freely with respect to the cylinder 10 surface. There will therefore be no slipping between textile substrate T and interposition tape 63. The textile substrate T will therefore not be disturbed by the interposition tape and may therefore follow the contraction movements of the belt 20, to the benefit of a correct performance of the compaction process.
Compared to the case of two distinct interposition tapes 61 and 62, the use of a single tape 63 avoids the need to adjust the winding position around the cylinder 10.
However, the embodiment with two distinct tapes 61 and 62 adjustable in position is preferred since in this way the tape 20 substantially does not encounter thickness discontinuities in its winding around the cylinder 10. On the other hand, in the case of a single tape 63, at the side edges of the textile substrate T, the tape 20 encounters a reduction in thickness, which could disturb it.
Advantageously, as illustrated in the accompanying figures, each of said one or more interposition tapes 61, 62 and 63 forms an endless belt which is wound around the cylinder 10 and a guide system comprising one or more return rollers 71, 72.
Preferably, the two distinct interposition tapes 61, 62 are both guided by the same guide system.
Advantageously, the friction reduction system described above is applicable in any compacting apparatus with elastic belt, which provides for the pretensioning of the belt itself.
Preferably, as illustrated in the accompanying figures, the friction reduction system according to the invention is applied to a compacting apparatus as described below.
The above roller system on which the belt 20 is wound in an elongation pre-tensioning state comprises:

a motorized drive roller 31;
a motorized brake roller 32;
a first idle return roller 33, which is arranged between the motorized brake roller 31 and the motorized brake roller 32; and
a second idle return roller 34.

With reference to the direction of advancement X of the belt 20 along the closed path, the motorized drive roller 31 is the roller placed immediately upstream of the heatable cylinder 10, while the second idle return roller 34 is the roller placed immediately downstream of the heatable cylinder 10.
The first section T1 of the aforementioned closed path (at which the belt 20 is in use elastically elongated, receiving an additional tensional state of elongation with respect to the pretensioning one) extends between the motorized brake roller 32 and the motorized drive roller 31, passing in partial winding around the first idle return roller 33.
The second section T2 of path (at which the belt 20 in use contracts itself, losing the additional tensional state of elongation to return to the pretensioning state) extends between the motorized drive roller 31 and the second idle return roller 34.
The above closed path is completed by a third section T3 of path extending between the second idle return roller 34 and the motorized brake roller 32. In use, along such a third section T3 of path, the belt 20 is in a relaxed tension state with respect to the first section T1 of path, substantially corresponding to the pretensioning state.
The "closed path" corresponds to the total extension of the belt 20 when mounted in pretension on the roller system. The closed path is not affected by local contractions and local elongations of the belt.
Thanks to this particular configuration of the roller system, a section of path - distinct from that of contraction in contact with the cylinder - is provided in the closed path, in which the belt is free to progressively return to the pretensioning state, without being subject to an additional elongation state.
On the other hand, in the prior art solutions which provide for the pretensioning of the belt, but with a different configuration of the roller system, referring to the tensional state of the belt, the closed path of the belt is divided into only two sections:

a first "elongation" section, which extends from a brake roller arranged immediately downstream of the heatable cylinder to a drive roller arranged immediately upstream of the heatable cylinder; and
a second "contraction" section, which extends from the drive roller to the brake roller, partially winding the heatable cylinder.

According to the prior art, the belt is therefore continuously stressed in elongation or contraction, without actually being able to remain in the pretensioning state, that is in the state of minimum elongation, which may be considered the rest state. In fact, already immediately downstream of the brake roller, the belt begins to undergo the elongation action exerted by the drive roller.
Conversely, thanks to the aforementioned configuration of the roller system, the aforementioned third section T3 has been introduced in the closed path, in which the belt - after having contracted in the second section T2 - is free to remain in the pretensioning state. In other words, the third section T3 may be considered a rest section for the belt, as opposed to the first elongation section T1 and the second contraction section T2.
This has a number of advantages:

the tensional elongation action exerted on the belt is concentrated on a shorter section of path (being equal the extension of the closed path and the second section T2); in this way, by acting on the speeds of the motorized drive and brake rollers, it is possible to control more precisely the elongation imposed on the belt, with consequent better control on the compacting action of the textile substrate;
the belt is less mechanically stressed, since, after having contracted, it is free to reach the rest state and remain so for a certain section; the reduction of stress on the belt allows the useful life of the belt itself to be extended.

These advantages are enhanced by the adoption of the friction reduction system according to the present invention.
Preferably, the motorized drive 31 and brake 32 rollers, the idle return rollers 33, 34, 35, as well as the heatable cylinder 10 are made of metal, preferably steel.
According to a particularly preferred embodiment of the invention, as illustrated in the accompanying figures, the motorized brake roller 32 and the motorized drive roller 31 are both provided with a rubber coating 36 which covers the respective cylindrical side surfaces intended to contact the belt 20.
By virtue of the rubber coating 36 of the motorized rollers, the friction coefficient between the motorized rollers and the belt is increased with respect to the case of contact of the belt on the bare surface of the cylinder, typically smooth metal.
Operatively, the increase in the friction coefficient reduces the risk of slipping between the belt and the rollers. This contributes to improving the control over the elongation action of the belt and therefore to increasing the efficiency of the compaction process of the textile substrate.
Preferably, both the first idle return roller 33 and the second idle return roller 34, unlike the two motorized rollers 31 and 32, are not rubber-coated. In other words, both the first idle return roller 33 and the second idle return roller 34 are provided with a cylindrical side surface, preferably made of metal material, intended to come into direct contact with the belt 20 without the interposition of a rubber coating covering such a cylindrical side surface.
Operatively, since the idle return rollers 33 and 34 are not rubber-coated and the elastic belt 20 comes into direct contact with their metal side surface, the friction between the belt and the idle rollers is reduced. In this way, by virtue of the reduction of friction, the belt encounters fewer obstacles in its elastic extension and subsequent contraction.
Operationally, the additional tensional state of elongation is imposed on the belt 20 by acting on the speeds of the motorized drive roller 31 and the motorized brake roller 32, so as to create a difference between the tangential speeds of the side surfaces of the two rollers (intended to contact the belt). The tensional state of elongation (measurable for example by percentage of elongation with respect to the pretensioning state) increases as the difference in these speeds increases.
Advantageously, the apparatus 1 may comprise a control unit 50, preferably electronic, configured to control the rotation of the motorized drive roller 31 and of the motorized brake roller 32 so that said two motorized rollers 31, 32 rotate in the same direction and so that the tangential speed Vt of the motorized drive roller 31 is higher than the tangential speed Vf of the motorized brake roller 32 according to a predefined ratio Vf/Vt.
Advantageously, such a predefined ratio Vf/Vt between the tangential speed of the motorized brake roller 32 and the tangential speed of the motorized drive roller 31 is adjustable as a function of the extent of additional longitudinal elongation to be imposed on the belt at the first section of path T1.
Preferably, said predefined ratio Vf/Vt is between 0.5 and 0.9, and preferably equal to 0.7.
Preferably, the heatable rotating cylinder 10 is motorized. By "heatable cylinder" it is meant in particular a cylinder provided with or associated to heating means. The heating means can be of any type suitable for the purpose, i.e. heating the surface of the rotating cylinder.
Advantageously, the control unit 50 is configured to control the rotation of the heatable cylinder so that its tangential speed (referred to the side surface 10a) - is as close as possible to and preferably equal to the tangential speed of the motorized drive roller 31.
It was possible to verify that in these conditions the best results are obtained in terms of compaction of the textile substrate. In other words, under these conditions, the efficiency of the compaction process is increased.
Preferably, the motorized drive roller 31, the motorized brake roller 32 and the first idle return roller 33 are positioned in relation to each other such that the above first section T1 of the closed path has a length extension not exceeding 35% of the entire closed path, and preferably not lower than 10%.
Advantageously, as schematically shown in Figure 1, the motorized drive roller 31, the motorized brake roller 32 and the first idle return roller 33 are positioned in relation to each other so as to assume a compact configuration. Compact configuration refers to a configuration in which said three rollers 31, 32, and 33 are in close proximity to each other when compared with the other rollers 34 and 35 of the roller system.
The "compact configuration" is essentially aimed at reducing as much as possible the extension of the first section T1 of the path in favor of the third section T3 of the path.
In particular, said three rollers 31, 32, and 33 may be arranged to form a triad of rollers with aligned centers of rotations. This choice is preferred from a constructive point of view as it allows a reduction in the overall dimensions and simplifies the support structure of the rollers themselves. However, configurations of the triad of rollers may be provided in which the rollers are not aligned with each other.
Preferably, the motorized drive roller 31, the motorized brake roller 32 and the first idle return roller 33 are positioned in relation to each other such that the winding angle of said belt 20 around the motorized drive roller 31 and the motorized brake roller 32 is not lower than 90°.
In particular, as shown schematically in Figure 1, the belt is installed on the triad of rollers so as to follow an S-path between the three rollers. In particular, the two motorized rollers 31 and 32 contact the belt on its inner surface, while the first idle return roller 33 contacts the belt on its outer surface. The first idle return roller 33, interposed between the two motorized rollers 31 and 32, may thus push the belt against them, favoring the winding of the belt. The "push" action of the return roller and therefore the effect in terms of winding may be calibrated by operating on the nominal diameters of the rollers and/or on the relative position of the centers of rotation.
Operatively, the higher the winding angle of the belt on the drive roller 31 and the brake roller 32, the greater the friction that is generated between the motorized rollers and the belt and therefore the more efficient the dragging action of the rollers on the belt, with reduction of the phenomena of slippage between roller and belt.
This contributes to improving the control over the elongation action of the belt and therefore to increasing the efficiency of the compaction process of the textile substrate.
As already mentioned above, with reference to the direction of advancement X of the belt 20 along the closed path, the motorized drive roller 31 is the roller placed immediately upstream of the heatable cylinder 10, while the second idle return roller 34 is the roller placed immediately downstream of the heatable cylinder 10.
Preferably, the motorized drive roller 31 and the second idle return roller 34 are positioned with respect to the cylinder 10 so that:

the distance D1 between the side surface 31a of the motorized drive roller 31 and the side surface 10a of the cylinder 10 is equal to or less than the thickness S of the belt 20; and
the distance D2 between the side surface 10a of the cylinder 10 and the side surface 34a of the second idle return roller 34 is equal to or greater than the thickness S of the belt 20.

Preferably, the aforesaid distance D1 is less than the thickness S of the belt 20 by a value of between about 0% and about 50%; the aforementioned distance D2 is greater than the thickness S of the belt 20 by a value of between about 0% and about 100%.
Advantageously, the aforesaid second idle return roller 34 is movable with respect to the other rollers 31, 32, 33 to vary their relative position and allow:

assembly and disassembly of the belt on said roller system;
belt maintenance operations; and
pretensioning of the belt 20.

According to a particularly preferred embodiment, shown in Figure 1, the second idle return roller 34 is movable with respect to the other rollers 31, 32, 33 along an arc of circumference concentric to the axis of rotation of the cylinder 10 between a position of maximum winding of the belt around the cylinder and a position of minimum winding around the cylinder.
For this purpose, the second idle return roller 34 is slidably engaged at both its axial ends to a guide (not shown in the accompanying Figures) shaped according to said arc of circumference.
Advantageously, the second idle return roller 34 is lockable both in the aforementioned two extreme positions of the aforementioned arc of circumference, and in one or more intermediate positions, so as to adjust the extension of said second section T2 of the closed path and therefore the degree for winding the belt around the cylinder 10. In this way it is possible to calibrate the compaction effect on the textile substrate according to the requests dictated by the type of fiber and the result to be obtained. In this way, it is also possible to improve and decrease the friction effect of the belt on the hot cylinder precisely due to the decrease in the winding angle. This has a benefit on the result of the compaction process.
The locking of the second idle return roller 34 along the aforesaid shaped guide may be carried out by means of brackets which also include the bearings suitable for rotating the pin of the roller and which may be fixed, for example, by means of screws to the support structure of the apparatus. In particular, the fixing of the roller takes place at shoulders suitably perforated in advance along said guide in predefined angular positions corresponding to the adjustment positions to be provided.
Preferably, as shown in Figure 1, the arc of circumference has an extension of 90°. Arcs of circumference with smaller width may be provided according to operational needs.
The adjustment of the position of the second idle return roller 34 with respect to the cylinder 10 modifies the tensioning state of the belt.
Preferably, as illustrated in Figure 1, the apparatus 1 comprises a third idle return roller 34 which engages the belt at the third section T3 of the path and is movable with respect to the other rollers 31, 32, 33 to compensate for the position variations of the second idle return roller 34.
Similarly to what is provided for the second idle return roller 34, also the third idle return roller 35 is slidably engaged at both its axial ends to a suitably shaped guide (not shown in the accompanying Figures). The third idle roller 35 may also be fixed and stopped also in intermediate positions between two maximum and minimum compensation positions. The fixing may take place by means of brackets which include the roller bearings and which will be fixed by screws at the shoulders of the apparatus suitably perforated at the predefined positions.
Preferably, like the first and second idle return rollers 33 and 34, also the third idle return roller 35 is not rubber-coated. In other words, also the third idle return roller 35 is provided with a cylindrical side surface, preferably made of metal material, intended to come into direct contact with the belt 20 without the interposition of a rubber coating covering such a cylindrical side surface.
Operationally, as already mentioned in relation to the idle return rollers 33 and 34, also for the third idle return roller 35, by virtue of the absence of rubber-coating and therefore of the fact that the elastic belt 20 comes into direct contact with the metal side surface of such a third idle roller 35, the friction between the belt and the idle roller is reduced. In this way, by virtue of the reduction of friction, the belt encounters fewer obstacles in its sliding, avoiding localized tensions due to friction.
Preferably, the above belt 10 is elastically deformable in elongation for a percentage between 5% and 100% of its length in the relaxed state before pre-tensioning and, preferably in its pre-tensioning state, for a percentage between 30% and 50% with respect to its relaxed length.
Preferably, the belt 20 has a thickness S comprised between about 4.0 mm and about 16.0 mm and, preferably, of about 10 mm.
The belt 20 may be made of a substantially extensible and elastic material, in particular of natural or synthetic rubber, or combinations thereof. Advantageously, the material may contain additives suitable for improving the mechanical and heat resistance features thereof.
The invention allows several advantages to be achieved, some of them already described.
The apparatus for compacting textile substrates by means of elastic belt according to the invention allows making the compaction of the textile substrate more efficient and increasing the operating life of the elastic belt due to a reduction of the frictions between the belt and the cylinder.
The apparatus for compacting textile substrates by means of elastic belt according to the invention allows the stresses imposed on the elastic belt during use to be reduced, and in particular in the contraction zone around the heatable cylinder.
The apparatus for compacting textile substrates by means of elastic belt according to the invention is simple and cost-effective to manufacture.
The apparatus for compacting textile substrates by means of elastic belt according to the invention may be managed in an operationally simple way.
The apparatus for compacting textile substrates by means of elastic belt according to the invention allows in particular - due to a specific configuration of the roller system - the tension of the elastic belt to be controlled more precisely so as to make the fabric compacting process more efficient.
The apparatus for compacting textile substrates by means of an elastic belt according to the invention allows reducing the stresses imposed on the elastic belt during use, as a whole and not only at the contraction zone.
Further advantages obtainable with the compacting apparatus according to the invention are listed below:

High precision of belt elongation thanks to the use of rubber rollers;
Perfect drive guarantee without belt slippage on the drive and brake rollers thanks to the wide winding angle on the rollers themselves (given by the interposed idle roller)
High process speed, high productivity
High compaction efficiency, high compaction value for all fabrics
It does not require having to go over the same fabric several times in the apparatus to obtain a correct compaction value (process carried out in one step)
Possibility to treat both orthogonal (shuttle) and knitted fabrics
Possibility to treat all types of fiber used for shuttle and knitted fabrics
Excellent compaction results at high speed even with viscose fiber fabrics
Excellent results of compaction at high speeds even with cotton fiber and denim-like fabrics

Obviously, it may take, in its practical embodiment, also shapes and configurations other than the above without departing from the present scope of protection.
Furthermore, all details may be replaced with technically equivalent elements and dimensions, shapes and materials used may be any according to the needs.

Claims

An apparatus for compacting a continuous textile substrate (T) by means of elastic belt, comprising:
- a heatable rotating cylinder (10);

- an endless belt (20) movable along a closed path (P) to support and transport the textile substrate (T) in contact with a side surface portion (11) of said heatable rotating cylinder (10), said belt being elastically deformable in elongation;

- a roller system (31, 32, 33, 34, 35) on which said belt (20) is wound in an elongation pretensioning state, wherein said roller system comprises a plurality of idle return rollers (33, 34, 35) and a plurality of motorized rollers (31, 32) operable so as to make said belt (20) to slide along said closed path (PC) imposing on said belt an additional elongation tension state at a first section (T1) of said path extending - with respect to a direction of advancement (X) of the belt - upstream of a second section (T2) of said path in which said belt (20) is maintained in contact with the rotating cylinder;

- means (40) for guiding said textile substrate (T) between said belt (20) and said heatable cylinder (10) along said second section (T2) of said path,
characterized in that it comprises a system for reducing friction coefficient between the belt (20) and the heatable rotating cylinder (10), said system for reducing friction coefficient comprising one or more interposition tapes (61, 62; 63) that:
- are guided in partial winding around said cylinder (10) and in direct contact with its side surface (10a) to interpose themselves between said belt (20) and the side surface (10a) of said cylinder (10) along said second section (T2) of the closed path of the belt at least at two axial end strips (11, 12) of the side surface of said cylinder (10) that are in axially opposite positions with respect to the axis of rotation (Y) of said cylinder; and

- are made of a material that is suitable to generate with the side surface of the cylinder (10) a friction coefficient lower than that generated with the belt (20).
Apparatus according to claim 1, wherein said system for reducing friction coefficient comprises two distinct interposition tapes (61, 62) that are guided in partial winding around said cylinder (10) and in direct contact with its side surface to interpose themselves between said belt (20) and the side surface of said cylinder (10) along said second section (T2) of the closed path of the belt and wherein a first interposition tape (61) is guided at a first axial end strip (11) of the side surface (10a) of said cylinder (10) and a second interposition tape (62) is guided at a second axial end strip (12) of the side surface (10a) of said cylinder (10), said two interposition tapes (61, 62) leaving uncovered a central strip (13) of the side surface (10a) of the cylinder (10) to allow in use a textile substrate (T) to be treated to slide in direct contact with the cylinder (10).
Apparatus according to claim 2, wherein the axial winding position of both or at least one of said interposition tapes (61, 62) around said cylinder (10) is adjustable so as to vary the width in the axial direction (height) of said uncovered central strip (13).
Apparatus according to claim 1, wherein system for reducing friction coefficient comprises a single interposition tape (63) that is guided in partial winding around said cylinder (10) and in direct contact with its side surface to interpose itself between said belt (20) and the side surface of said cylinder (10) along said second section (T2) of the closed path of the belt and wherein said single interposition tape (63) has an axial extension (H3) at least equal to the axial extension (Hn) of the belt (20), in use said single interposition tape (63) interposing itself between the textile substrate (T) to be treated and the side surface of said cylinder (10).
Apparatus according to one or more of the preceding claims wherein each of said one or more interposition tapes forms an endless belt that is wound around said cylinder and around a guide system comprising one or more return rollers (71, 72).
Apparatus according to claim 2 or 3 and claim 5, wherein said two distinct interposition tapes (61, 62) are both guided by the same guide system.
Apparatus according to one or more of the preceding claims, wherein said one or more interposition tapes are made of fabric or non-woven fabric.
Apparatus according to one or more of the preceding claims, wherein said one or more interposition tapes are made of a fabric of natural textile fibers, preferably selected from the group consisting of cotton, wool, cellulose.
Apparatus according to one or more of the preceding claims, wherein said one or more interposition tapes are made of a fabric or a non-woven fabric of synthetic fibers, preferably selected from the group consisting of polyester and nylon.
Apparatus according to one or more of the preceding claims, wherein said one or more interposition tapes are made of a mixed fabric of natural fibers and synthetic fibers.
Apparatus according to any one of claims 7 to 10, wherein said fabric or said non-woven fabric comprises elastomeric fibers.
Apparatus according to one or more of claims 7 to 11, wherein said fabric or said non-woven fabric has a weight not lower than 50g/m2.
Apparatus according to one or more of the preceding claims, wherein said roller system comprises a motorized drive roller (31), a motorized brake roller (32), a first idle return roller (33), which is arranged between said motorized drive roller and said motorized brake roller, and a second idle return roller (34),
and wherein the first section (T1) of said path extends between said motorized brake roller (32) and said motorized drive roller (31), passing in partial winding around said first idle return roller (33), while said second section (T2) of path extends between said motorized drive roller (31) and said second idle return roller (34), wherein said closed path is completed by a third section (T3) extending between said second idle return roller (34) and said motorized brake roller (32), in use along said third section (T3) of path said belt (20) being in a relaxed tension state with respect to the first section (T1) of path.
Apparatus according to claim 13, wherein said motorized brake roller (32) and said motorized drive roller (31) are both provided with a rubber coating covering the respective cylindrical side surfaces intended to come into contact with said belt (20).
Apparatus according to claim 14, wherein said first idle return roller (33) is provided with a cylindrical side surface made of metal material, intended to come into direct contact with said belt (20) without the interposition of a rubber coating covering said cylindrical side surface.
Apparatus according to any of the claims 13, 14 or 15, wherein said second idle return roller (34) is provided with a cylindrical side surface made of metal material, intended to come into direct contact with said belt (20) without the interposition of a rubber coating covering said cylindrical side surface.
Apparatus according to any of claims 13 to 16, wherein said motorized drive roller (31), said motorized brake roller (32) and said first idle return roller (33) are positioned in relation to each other such that said first section (T1) of the closed path has a length extension not exceeding 35% of the entire closed path, and preferably not lower than 10%.
Apparatus according to any of claims 13 to 17, wherein said motorized drive roller (31), said motorized brake roller (32) and said first idle return roller (33) are positioned in relation to each other such that the winding angle of said belt (20) around said motorized drive roller (31) and around said motorized brake roller (32) is not lower than 90°.
Apparatus according to any of claims 13 to 18, comprising a control unit (50) configured to control the rotation of said motorized drive roller (31) and said motorized brake roller (32) so that said two motorized rollers (31, 32) rotate in the same direction and so that the tangential speed (Vt) of said motorized drive roller (31) is higher than the tangential speed (Vf) of said motorized brake roller (32) according to a predefined ratio (Vf/Vt).
Apparatus according to claim 19, wherein said predefined ratio (Vf/Vt) between the tangential speed of said motorized brake roller (32) and the tangential speed of said motorized drive roller (31) is adjustable as a function of the extent of longitudinal elongation to be imposed on said belt at said first section (T1) of said path.
Apparatus according to claim 20, wherein said predefined ratio (Vf/Vt) is between 0.5 and 0.9, and preferably equal to 0.7.
Apparatus according to any of the preceding claims, wherein the heatable cylinder (10) is motorized.
Apparatus according to any of the claims 19, 20 or 21 and claim 22, wherein said control unit (50) is configured to control the rotation of said heatable cylinder (10) so that its tangential speed - referred to its side surface (10a) - is as close as possible to and preferably equal to the tangential speed of the motorized drive roller (31).
Apparatus according to any of claims 13 to 23, wherein said second idle return roller (34) is movable with respect to the other rollers (31, 32, 33) to vary its relative position and allow the assembly and pretensioning of said belt (20) on said roller system.
Apparatus according to any of claims 13 to 24, wherein said second idle return roller (34) is movable with respect to the other rollers (31, 32, 33) along an arc of circumference concentric to the rotation axis of the cylinder (10) between a maximum winding position of the belt around said cylinder and a minimum winding position around said cylinder and is lockable in one or more intermediate positions between said two positions to adjust the extension of said second section (T2) of the closed path
and wherein said apparatus (1) comprises a third idle return roller (34) that engages said belt at said third section (T3) of the path and is movable with respect to the other rollers (31, 32, 33) to compensate for the position variations of said second idle return roller (34) and thus maintain the pretension of said belt.
Apparatus according to claim 25, wherein said first idle return roller (34) is provided with a cylindrical side surface made of metal material, intended to come into direct contact with said belt (20) without the interposition of a rubber coating covering said cylindrical side surface.
Apparatus according to any of the preceding claims, comprising means for wetting with an aqueous solution, preferably only with water, said one or more interposition tapes (61, 62; 63).