Compaction device for fabrics

Abstract: Perfected compaction device for fabrics, comprising at least an operating unit (11a, 11b) consisting of a heated metallic cylinder (13) and a pressing element with a felt strip (17), the fabric (15) being guided between the cylinder (13) and the felt strip (17) by a lead-in element (16), downstream of the operating unit (11a, 11b) there being included at least a drying assembly (30), the heated metallic cylinder (13) being covered with a sheath or sleeve (20) made of soft material and of the appropriate thickness, the sheath or sleeve (20) being associated, at least upstream of the area of contact with the fabric (15), with a steaming device.

Description: FIELD OF THE INVENTION This invention concerns a perfected compaction device for fabrics as set forth in the main claim. The invention is applied in finishing operations for fabrics to guarantee that the fabric has a high and efficacious stability of size before it is sent for making up, giving the fabric an aesthetic effect and an extremely soft hand. BACKGROUND OF THE INVENTION In finishing operations for fabrics, particularly woollens, the state of the art includes the procedure of compacting the fabric before it is packaged in order to guarantee that the fabric has the necessary stability of size to satisfy the requirements of quality demanded by those making up the fabrics and by the market itself. The machines used to perform this process are basically divided into two categories. The first category consists of compaction machines with a shuttle, where the operational centre is represented by a carpet of very thick natural rubber, as much as 70 mm thick, which works by crushing and subsequently swelling the fabric, coupled with a heated stabilising cylinder. The second and more important category consists of compaction machines with a mesh, where the operating centre is represented by a thick strip of felt combined with a lead-in and supporting element, known as shoe, and with a cylinder of heated steel which acts as a stabiliser. The fabric which is to be compacted is inserted between the felt and the heated cylinder. The working principle on which felt compaction machines are based, both for open mesh fabrics and for tubular fabrics, is the different speed of the fabric between the lead-in zone, where it is brought into contact with the felt, and the stabilisation zone where it is compressed by the felt against the heated cylinder. In the lead-in zone the peripheral speed of the felt is greater than the speed at which the felt and fabric wind together around the heated cylinder. This difference in speed causes the felt to dilate as it winds around the small diameter roller, and then to shrink as soon as the felt begins to wind around the heated cylinder, returning to a direction which can be considered substantially rectilinear. The fabric is brought into contact with the felt when the latter is in its condition of maximum dilatation; during the subsequent segment, the fabric is clamped between the felt and the lead-in element and is therefore obliged to follow the variation in the peripheral speed of the felt, and particularly the slowing down and shrinking of the felt in the area of stabilisation around the heated cylinder, and is then subjected to a forcible lengthwise compaction. The surface of the felt also has a roughness, and therefore a coefficient of friction, which is much greater than that of the surface of the lead-in element; it is therefore the felt, as it shrinks, which causes a similar effect on the fabric. The compaction parameters can be adjusted by acting on the thickness of the felt, on the diameter of the winder roller, on the position of the lead-in element. This type of machine, which is nowadays in standard use, does not make it possible to obtain optimum quality for every type of fabric. To be more exact, winding around the heated metallic cylinder gives the hand of the fabric a crushed effect on the fibres and a shiny effect which has a negative effect on the final quality, particularly for raised fabrics and/or high-quality fabrics and/or particularly delicate fabrics. The final result obtained therefore does not have those characteristics of softness which the compaction process is intended to give, especially in the case of dark-dyed fabrics and mixed fibre fabrics, which accentuate the negative effect of shininess and surface crushing. Various proposals have been made, but they have all been shown to be only partially effective, insufficient to ensure satisfactory results which are consistent under all conditions. EP-A-0.457.273 (preamble of claim 1) discloses an apparatus for compressive shrinking of textile knitwear, on which the knitwear is shrunk in a shrinking channel formed by a shrinking roller and a shrinking cloth partly surrounding this roller. The shrinking roller is covered with a covering elastic such as felt or wool, for improving the roller-facing surface of the knitwear. EP-A-0.295.534 discloses an apparatus for shrinking fabric material comprising means for stretching the material and means for moistening the stretched material. The apparatus further comprises a shrinkage belt which presses one side of the material against a support roller and first and second smoothing and shrinking units. The present Applicant has designed, tested and embodied this invention to overcome the shortcomings of the state of the art, and to obtain further advantages. SUMMARY OF THE INVENTION The invention is set forth and characterised in the main claim, while the dependent claims describe other features of the idea of the main embodiment. The purpose of the invention is to achieve a compaction device for fabrics which will make it possible to eliminate. the problems of shininess and residual crushing of the fibres in the final fabric, optimising the results of the compaction process and obtaining a product characterised by a high degree of softness in the hand, whatever the type and colour of the fabric concerned. The invention is applied to compaction machines using felt of the type described above, using a thick strip of felt combined with a heated metallic cylinder. According to the invention, the heated metallic cylinder around which the fabric is pressed by the felt is covered by a sheath or sleeve made of soft material and of the appropriate thickness. The sleeve is subjected, at least at a position upstream of the area of contact with the fabric, to a steaming treatment carried out by an appropriate steaming device. In a first embodiment, the sleeve is steamed by means of a steaming device which acts from outside, advantageously positioned at a position immediately upstream of the area where the fabric is introduced. According to a variant, the sleeve is steamed by introducing the steam inside the heated cylinder, which has in this case a perforated surface to allow the steam to emerge from the cylinder and towards the sleeve. According to a variant of this embodiment, inside the perforated cylinder there is a shutter element which allows the steam introduced inside the cylinder to be conveyed only into the area which is in direct contact with the fabric. The fact that there is a soft surface in contact with the fabric, and that this surface is dampened, before and/or after it comes into contact with the fabric, ensures that an extremely soft finish is obtained, which drastically reduces the shiny effect and the crushed effect on the surface of the fabric, and gives a soft and full hand, both visually and to the touch. According to a further variant, the sleeve is subjected to a localised heat treatment, achieved by an outside source of heat, which serves to prepare the surface of the sleeve before the steaming process, thus further improving the efficaciousness of the surface finish on the fabric. In a further embodiment of the invention, the compacted fabric emerging from the heated cylinder is subjected to a further steaming treatment before it is subjected to the usual cooling step. This steaming treatment serves to swell the fabric immediately after it has been compacted, thus removing all the residual shiny effect and crushed effect caused by the compaction operation carried out upstream. According to a further variant, the cooling step and final drying step of the fabric is carried out using air which, before being sent onto the fabric, is subjected to an appropriate conditioning, achieved by the heat exchange group supplied for this purpose. BRIEF DESCRIPTION OF THE DRAWINGS The attached Figures are given as a non-restrictive example, and show some preferential embodiments of the invention as follows: Fig. 1 shows in diagram form a perfected compaction device for fabrics according to the invention; Fig. 2 shows a variant of Fig. 1, with an enlarged detail; Fig. 3 shows a variant of Fig. 2; Fig. 4 shows a variant of Fig. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The compaction device 10 shown in Fig. 1 comprises two operating units 11a and 11b, for the treatment in sequence of both sides of the fabric 15, and a drying and discharge assembly 12 located downstream. Each operating unit 11a and 11b comprises a metallic cylinder 13, of a substantially known type, the surface of which is heated also in a known manner. Upstream of the first operating unit 11a there is a steaming assembly, in this case of the type with a steam bath 14, which serves to dampen the fabric 15 before it is sent to the first compaction step. At inlet to the first operating unit 11a there is a lead-in element 16, or shoe, which guides the fabric 15 between the surface of the heated cylinder 13 and a strip of compacting felt 17. The felt 17 is wound, in a known manner, in a closed ring between three return rollers 18. The fabric 15 emerging from the first operating unit 11a is sent by return and tensioning rollers 19 to the second operating unit 11b for the other side of the fabric 15 to be treated. In this case, only the operating unit 11b has the innovative characteristics according to the invention, but it is within the scope of the invention that the first operating unit 11a may also be equipped with the same devices as the operating unit 11b. To be more exact, in this case the heated metallic cylinder 13 of the operating unit 11b is lined with a sleeve 20 of soft material, for example felt, which is of a suitable thickness to ensure the desired softness. The fabric 15 is guided by the lead-in element 16 and is then compressed between two soft surfaces, the felt 17 and the sleeve 20, so that the risk of causing a shiny and crushed effect on the fabric 15 during the compaction step is reduced to a minimum. In the case shown in Fig. 1, moreover, the sleeve 20 is dampened, upstream of the area where the fabric 15 is introduced, by means of a steam pipe 21 associated with a direction screen 22, which sprays the steam against the surface of the sleeve 20 from outside. The surface of the sleeve 20, at the moment when it comes into contact with the fabric 15 and also during the compression step, is therefore appropriately damp so that the softening effect is further increased. In the variant shown in Fig. 2, to further optimise the result, upstream of the steam pipe 21 there is a radiance heating assembly 23, in this case of the type using infrared lamps, which heats the surface of the sleeve 20 before it is subjected to steaming. This surface heating improves the capacity of the sleeve 20 to absorb the humidity generated by the steam pipe 21 and therefore improves the performance and the final quality obtained after the fabric 15 has passed through the second operating unit 11b. In the embodiment shown in Figs. 3 and 4, the sleeve 20 which lines the heated metallic cylinder 13 is steamed by introducing the steam inside the cylinder 13 through one of its extremities, and causing the steam to emerge through its surface, which is suitably perforated. The sleeve 20 is thus lapped by the steam around its whole circumference and is thus suitably dampened for the whole arc of contact with the fabric 15. According to the variant shown in Fig. 4, part of the inner circumference of the heated metallic cylinder 13 is screened by a shutter element 24 which prevents the steam inside the cylinder 13 from emerging into the area of no-contact with the fabric 15. This gives a more intense dampening of the affected area of the sleeve 20 or, alternatively, a saving of energy in generating the steam. When the compaction step is finished, the fabric 15 emerging from the second operating unit 11b is sent to a drying assembly 30 consisting of an intake and/or cooling assembly, and is then discharged. In this area the compacted fabric 15, which is still warm, rests on a conveyor belt 25 which winds between a driven cylinder 26 and a return cylinder 27, the whole being supported by a structure 31. The conveyor belt 25, according to the invention, is made of hard-wearing plastic material, for example polyester, and the surface is perforated to allow the air to pass through. The speed of the conveyor belt 25 is suitably controlled and is synchronised to the speed at which the fabric 15 emerges from the operating unit 11b by means of a dandy roll 28. Between the outlet of the second operating unit 11b and the drying assembly 30, in this case there is a steaming assembly 29, with the function of swelling the fabric 15 which has just been compacted, before its hand is definitively stabilised by cooling and drying. In this case, the steaming assembly 29 is located inside the conveyor belt 25 and the steam is transmitted to the fabric 15 through the holes on the conveyor belt 25 itself. During this step it is extremely important that the dandy roll 28 should prevent any longitudinal tension being generated on the fabric 15, which is in a substantially plastic condition due to the effect of the steam. This further steaming treatment, carried out in line, therefore ensures optimum conditions of softness of the hand of the fabric 15, conditions which are then stabilised by the drying step performed immediately downstream. In this case, the drying assembly 30 comprises (Fig. 1) an air-water exchange group 32 by means of which the natural air fed by the fan 33 and conveyed through the box 34 is cooled before being sent onto the fabric 15 which is passing over the conveyor belt 25. The exchange group 32 comprises pipes 35 for the circulation of water which, according to a variant which is not shown here, are connected to a cooling circuit which makes possible to obtain a thermal leap and therefore a much more intense and efficient cooling effect. This system to condition the drying air further improves the overall performance of the compaction device, both in terms of the final quality of the fabric 15 and in terms of the speed of the entire processing cycle.

Claims: Compaction device for fabrics, comprising at least an operating unit (11a, 11b) consisting of a heated metallic cylinder (13) and a pressing element with a felt strip (17), the fabric (15) being guided between the cylinder (13) and the felt strip (17) by a lead-in element (16), downstream of the operating unit (11a, 11b) there being included at least a drying assembly (30), wherein the heated metallic cylinder (13) is lined with a sheath or sleeve (20) made of soft material and of appropriate thickness, characterised in that said sheath or sleeve (20) is subjected to a steaming treatment carried out by a steaming device associated with said sheath or sleeve (20). Device as in Claim 1, characterised in that the steaming device comprises a steam pipe (21) arranged outside the sleeve (20) in a position upstream of the area of contact between the fabric (15) and the sleeve (20). Device as in Claim 2, characterised in that the steam pipe (21) is associated with means (22) to direct the steam against the surface of the sleeve (20). Device as in Claim 1, characterised in that the steaming device comprises means to introduce the steam inside the heated metallic cylinder (13), the surface of the heated metallic cylinder (13) being at least partly perforated to allow the steam to pass from the inside to the outside towards the sleeve (20). Device as in Claim 4, characterised in that at least the arc of the inner circumference of the heated metallic cylinder (13) corresponding to the area of no-contact with the fabric (15) is screened by a shutter element (24) which prevents the steam from emerging from inside the cylinder (13) to the outside. Device as in any claim hereinbefore, characterised in that it comprises a radiance heating assembly (23) arranged in cooperation with the surface of the sleeve (20) upstream of the area of contact with the fabric (15). Device as in Claims 2 and 6, characterised in that the radiance heating assembly (23) is located upstream of the steam pipe (21). Device as in any claim hereinbefore, characterised in that it comprises at least two operating units (11a, 11b) to compact both sides of the fabric (15) in sequence. Device as in any claim hereinbefore, characterised in that there is a steaming assembly (29) between the last operating unit (11b) and the drying assembly (30). Device as in any claim hereinbefore, characterised in that it comprises a conveyor belt (25) to support the fabric (15) between the last operating unit (11b) and the drying assembly (30), the conveyor belt (25) being made of hard-wearing plastic material and having an at least partly perforated surface. Device as in Claims 9 and 10, characterised in that the steaming assembly (29) is located inside the conveyor belt (25) below the surface supporting the fabric (15). Device as in Claim 1, characterised in that the drying assembly (30) comprises means (33) to send air onto the fabric (15) and means (32) to condition the air before it comes into contact with the fabric (15). Device as in Claim 12, characterised in that the means to condition the air consist of a group (32) of air-water heat exchange. Device as in Claim 12, characterised in that the heat exchange group (32) is connected to a cooling circuit. Device as in any claim hereinbefore, characterised in that between the last operating unit (11b) and the conveyor belt (25) there is a synchronisation element (28) to adjust the longitudinal tension of the fabric (15).

Inventors: SCORTEGAGNA BRUNO, SCORTEGAGNA, BRUNO
Applicants: LAFER SPA
Application year: 1999
Main classification: D06C21
IPC codes: D06C21