WET GRINDING METHOD FOR TEXTILE MATERIAL AND RELATIVE DEVICE

Abstract: Wet grinding method for textile material, applicable to textile material of cotton, wool, synthetic material, elasticised material and similar, used to give to the touch of the fabric particular aesthetic effects such as the ageing effect, the pre-washed effect, the "peach fuzz" effect, the method providing a preliminary step performed upstream of the grinding step wherein the fabric (11) is wet or dumped, the grinding step being performed by causing the fabric (11), maintained under tension between a drawing element at inlet (18) and a drawing element at outlet (24), to pass around a plurality of rotary grinding cylinders (22) distributed on the circumference of a rotary drum (21) and lined with material having abrasive properties. Wet grinding device for textile material, which can be used on textile material of cotton, wool, synthetic material, elasticised material and similar, used to give to the touch of the fabric particular aesthetic effects such as the ageing effect, the pre-washed effect, the "peach fuzz" effect, the device comprising means to wet or damp the advancing fabric (11) arranged upstream of the grinding assembly (19), the grinding assembly (19) comprising a plurality of rotary grinding cylinders (22) distributed on the circumference of a rotary drum (21), the device comprising at least a drawing element at inlet (18) and a drawing element at outlet (24) of the fabric (11), the grinding cylinders (22) being lined with material having abrasive properties.

Description: "WET GRINDING METHOD FOR TEXTILE MATERIAL AND RELATIVE DEVICE" * * * * * FIELD OF THE INVENTION This invention concerns a wet grinding method for textile material and the relative device as set forth in the respective main claims. The invention is applied in the finishing processing of fabrics and knitwear so as to give the touch of the fabric particular aesthetic effects, for example, the ageing effect, the pre-washed effect or the so-called "peach fuzz" effect . The invention can be applied substantially to any type of textile material, both in the field of cotton and in synthetic fibres, in the field of wool and knitwear. To be more exact, the invention is particularly indicated when applied to knitwear fabrics and/or fabrics which are at least partly elastic or elasticised. BACKGROUND OF THE INVENTION Grinding is well-known in finishing processes; it consists substantially of drawing the textile material around a plurality of rollers whose surfaces are covered with abrasive paper or some other material having abrasive properties . The action of the abrasive material partly removes fibrous material, thus causing the formation of a surface down which is more or less accentuated according to the final result desired or the characteristics of the touch to be obtained. In the state of the art, grinding is normally carried out on dry textile material, making the fabric pass around lined cylinders which are arranged horizontally and vertically. In order to obtain results of a higher quality, it has recently been proposed to carry out the grinding process on fabric which is wet or has at least been dampened before it is sent to the grinding rollers. To this end, the fabric is immersed in an impregnation tank, or subjected to a wetting or damping step using sprays, at a position upstream of the grinding zone. Compared with dry grinding, wet grinding has the characteristic that it causes a less accentuated and therefore more superficial abrasive action, it removes less fibrous material and raises the pile less, which leads to the creation of a short, thick pile. The treated product is extremely soft but no down is formed when the product is touched. Fabric which is wet fluffed is subject to fewer stresses and therefore loses less consistency and resistance. Wet grinding also makes it possible to apply to the fabric, during the impregnation step, particular chemical products, for example softeners, resin-based products or otherwise, so as to obtain the particular desired results in the touch, for example to increase softness, shine, or to give the fabric a fuller appearance. Downstream of the grinding zone there is normally a rinsing zone followed by a possible drying zone. The state of the art includes a wet grinding machine wherein the textile material is first immersed into an impregnation tank containing liquid, possibly with additives, and then sent to a series of rotary grinding cylinders, normally between 3 and 6 in number, arranged in a stationary position substantially on a single horizontal plane and separated by return rollers. The grinding cylinders are covered with abrasive material, for example abrasive paper, diamond-shaped paper or similar, and exert their grinding action in the brief segment wherein they are in contact with the fabric. This machine has a plurality of disadvantages. First of all, the time when the fabric and the grinding cylinder are in contact is very short which, together with the limited number of cylinders, obliges each of the cylinders to perform a very intense and concentrated individual action. The necessary high intensity of activity required by each grinding cylinder causes a more accentuated removal of fibrous material together with a greater raising of down, which gives an aesthetically less appreciable result, as well as a loss of resistance in the textile material treated. Another disadvantage of this machine is that, as the fabric approaches the impregnation tank, and during its immersion therein, and along the whole section when it cooperates with the grinding cylinders, it has long free segments when it is not supported or guided. Considering the fact that the fabric is wet, during the free segments it is subject to accentuated undulations, both longitudinal and transverse, which later, in the zones of contact with the grinding cylinders, cause obvious and unwanted irregularities in the processing. This phenomenon is very accentuated when knitwear fabrics or elasticised fabrics are being treated, and it is substantially impossible to use this machine on this type of fabric if good results are to be obtained in terms of both quality and uniformity. A further disadvantage is that the stationary position of the grinding cylinders does not cause any cooperation between the cylinders and the fabric except that given by the rotation of the cylinder. The stationary position of the grinding cylinder also involves problems concerning the efficacious washing of the surface of the circumferential zone which is not in contact with the fabric; it is therefore necessary to have recourse to particular configurations of the surface of the cylinder in order to have efficient results. The size of the cylinders must necessarily be large, which involves problems of construction, maintenance, assembly, transport, installation and other problems. The present Applicant has designed, tested and embodied this invention to overcome the shortcomings of the state of the art, adopting a solution which is extremely efficient, versatile, functional, adaptable to every type of fabric and able to guarantee results of extremely high quality. SUMMARY OF THE INVENTION The invention is set forth and characterised in the respective main claims, while the dependent claims describe variants of the idea of the main embodiment. The purpose of the invention is to provide a wet grinding process for textile material suitable to ensure high quality and uniform processing substantially of every type of textile material, also and particularly in the case of knitwear fabrics, elasticised fabrics and fine and light fabrics . Another purpose is to obtain the formation on the touch of the fabric of a layer of extremely short and thick down, characterised by great uniformity and regularity without compromising in any way the resistance of the fabric itself, since the grinding process is distributed uniformly over a large number of cylinders, each of which performs an action which is neither very intense nor very accentuated. A further purpose of the invention is to obtain a device which is extremely compact, functional and versatile in that it can be adapted to different types of processing and/or fabric; a device that is suitable to be integrated upstream or downstream with auxiliary devices for drying, rinsing, humidity adjustment or other types. According to the invention, the textile material to be sent for grinding is subjected to wetting or damping before being sent to the grinding cylinders. This wetting or damping treatment can take place, according to a first embodiment, by means of a guided immersion in an impregnation tank located upstream of the grinding zone. According to a variant, the fabric is wet or damped in advance by means of spray systems, shower systems or similar. After the wetting or damping step has been completed, and after a possible squeezing step which serves to regulate the humidity content in the fabric and to eliminate excess water, the fabric is sent to the grinding assembly. According to the invention, the grinding assembly consists of a structure with a rotary drum on the circumference of which are mounted a plurality of rotary cylinders which are small in diameter and lined with abrasive paper or some other desired material with abrasive qualities. The number of rotary grinding cylinders is variable and can be adapted according to the size of the drum and of the device . One embodiment of the invention provides to use at least sixteen grinding cylinders, advantageously between twenty- four and thirty-six. According to the invention, the diameter of the grinding cylinders is between 60 and 120 mm, advantageously around 80 mm. The idea of using grinding cylinders with a small diameter, defining a circular path and mounted on a rotary drum, has many advantages over the solutions known to the - o - art. First of all, the grinding action is distributed much better, as it is performed by a large number of cylinders each of which can exert an action which is not very intense or accentuated. It is thus possible to give the touch of the fabric a high level of uniformity and softness, without irregularities and without the formation of zones subject to treatments which are more or less accentuated. Moreover, the fabric is much less subject to points of maximum stress, so that its resistance is less compromised. Another advantage is that the fabric can be correctly accompanied and guided along its whole path starting from the impregnation zone and for the whole grinding zone; this prevents the formation of undulations and irregularities, both longitudinal and transverse, caused by the drawing action exerted on the wet fabric, which would have a negative effect on the uniformity of the processing. A further advantage is that the grinding effect is accentuated by the combined effect of the rotary grinding cylinders and the beating effect of the drum, which is also rotating. According to the invention, the fabric is unaccompanied, throughout the whole grinding path, for a maximum section of not more than three centimetres. The grinding device according to the invention provides means to draw the fabric arranged at inlet and outlet of the rotary drum and equipped with systems to regulate the drawing action so that the latter is adapted to the different characteristics of the fabric and to the different working conditions . According to a variant, the systems to regulate the drawing action comprise load cells. Upstream and/or downstream of the rotary drum there are squeezing systems which serve to regulate the humidity of the fabric both at the inlet to the grinding assembly and at the outlet thereof . According to a variant, the squeezing system at the outlet of the grinding assembly is associated with a rinsing tank. The device according to the invention comprises means to clean and wash the surface of the grinding cylinders in the zone where they come into contact with the fabric . In a first embodiment, the washing and cleaning means comprise spray elements oriented towards the cylinders and associated with means to feed the water under pressure. According to a variant, the washing and cleaning means comprise an impregnation tank wherein the grinding cylinders, rotating with the drum, are at least partly immersed. According to a variant, the rotary drum comprises means to make the grinding cylinders rotate also during the step when they are not in contact with the fabric, thus ensuring the maximum efficiency, over their whole circumference, of the washing and cleaning operation. In one embodiment, the rotation means comprise at least a belt or a chain, closed in a ring around the axes of the grinding cylinders and cooperating with the main drive chain which acts on the cylinders only during the section when they are in contact with the fabric. According to a variant, the impregnation tank wherein the fabric is immersed is associated with heating means. According to another variant, the means to wash and clean the grinding cylinders are associated with means to heat the washing liquid. According to a further variant, the device is equipped with a cover which can be opened so that dry fabric can also be processed, by creating a circulation of air by means of an air-intake tank cooperating with the rotary drum and through the aperture defined by the cover, since the boxlike structure containing the rotary drum is connected at its lower part to an electric aspirator. The rotary drum, like the grinding cylinders, can be equipped with rotation in both a clockwise and an anticlockwise direction, thus achieving all possible combinations . Moreover, the grinding cylinders, according to a variant, can be sub-divided into two groups with alternating cylinders for pile and counter-pile, for example the odd and even cylinders, associated with different and independent movement systems so as to achieve the desired combinations of movement in the same direction or in the opposite direction of one group of cylinders and the other. However, it is possible to achieve all the combinations desired, for example by making two adjacent cylinders rotate in one direction and a third in the opposite direction or otherwise. 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 a first embodiment of the grinding device according to the invention; Fig. 2 is a small scale view of a variant of Fig. 1; Fig. 3 is a diagrammatic view of the system to move the grinding cylinders on the rotary drum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The attached Figures 1 and 2 show two embodiments of the grinding device 10 for wet fabrics 11 according to the invention. The fabric 11, guided through an opportune accompanying and guiding system 12, which is shown diagrammatically here, is sent to an impregnation tank 13 wherein it is immersed to be wet . According to a variant which is not shown here, the wetting step can be carried out by a spray or shower system, or by some other similar system. In this case, there is a first change-of-direction roller 14 which stretches the fabric 11 and accompanies it to a return roller 15, from which the fabric 11 is then transferred to a second change-of-direction roller 16, completely immersed in the liquid of the impregnation tank 13 and from here to a second return roller 17. From the second return roller 17 the fabric 11 is sent to an inlet drawing roller 18 which sends it to the grinding assembly 19 itself. The configuration of the feed path achieved by the rollers 15, 16, 17 and 18 is such that the fabric 11, from the first section wherein it begins to be wet or damped - and therefore is more subject to tensions or undulations if subjected to a drawing action - has very limited free sections where it is not accompanied and guided, not more than 3 cm, advantageously not more than 2 cm. This ensures that, during the drawing step, no irregularities or deformations are formed in the fabric 11, either longitudinally or transversely, which would then have a negative effect on the uniformity and continuity of the grinding treatment carried out downstream. In this case, the impregnation tank 13 includes heating means 35 to adjust the temperature of the wetting liquid; this temperature can vary according to the invention in a range of between 15° and 98°C. According to a variant, the impregnation tank 13 includes means to add and measure out additives such as softeners, resin-based substances or otherwise so as to achieve particular treatments and effects on the fabric 11. In this case, the second return roller 17 cooperates with a squeezer roller 20 to perform a compression action on the fabric 11 as it enters the grinding assembly 19 so as to regulate the degree of humidity to a desired value, eliminating any excess liquid if necessary. The squeezer roller 20 can be adjusted at least in a direction radial to the mating second return roller 17 in order to grade the level of humidity within a range, according to the invention, of between 20 and 200%. The grinding assembly 19 comprises a drum 21 rotating around a central axis 23; on the circumference there is mounted a plurality, in this case twenty-four, of grinding cylinders 22 with a small diameter, for example of about 80 mm, covered with abrasive material, such as abrasive paper, diamond-shaped paper or similar. The fabric 11 winds round the grinding cylinders 22 for a substantial part of the circumference of the rotary drum 21, defined between the inlet drawing roller 18 and the outlet drawing roller 24. The drawing rollers, inlet 18 and outlet 24, are associated with systems to regulate the drawing action which are not shown here, for example load cells, so as to ensure the desired and correct tension of the fabric 11 around the grinding cylinders 22. Thanks to the combined action of the grinding cylinders 22, the grinding action on the fabric 11 is extremely uniform over a very wide zone, so that the action of the individual cylinder 22 can be made less accentuated and intense. This solution also allows to keep the fabric always accompanied, even during the actual grinding step, thus ensuring a minimal deformation of the fabric subjected to drawing and a minimal deterioration of the resistance of the fabric . The fabric 11 emerging from the grinding assembly 19 and picked up by the inlet drawing roller 24 is sent, in the case shown in Fig. 1, to a rinsing tank 25 wherein it is accompanied by return and change-of-direction rollers 115, 116 and 117 identical to those seen with reference to the impregnation tank 13. The rinsing tank 25, in an embodiment which is not shown here, can be replaced by spray or shower rinsing devices. It may also cooperate with heating devices and/or devices to add the desired softeners and/or processing substances. In this case, in cooperation with the rinsing tank 25 there is a shower unit 34 for washing the fabric and a unit to regulate the humidity comprising a squeezer roller 120 cooperating with the return roller 117. The humidity of the fabric 11 at outlet can be regulated to values within a range of between 20 and 200%. In the variant show in Fig. 2, the rinsing tank 25 is not included and the fabric 11 is sent immediately to the compression and humidity regulation unit comprising a squeezer roller 120, which also has the function of drawing and extracting the fabric 11 from the grinding assembly 19. Downstream of the humidity regulation unit there is, as shown in Fig. 1, a drying unit 26 of the radiant type. The fabric 11 is then sent, by means of a discharge system 27, to the appropriate collection and accumulation zones, which are not shown here. In this case, the grinding assembly 19 comprises a washing and cleaning system 28 for the surface of the grinding cylinders 22 in the area where they are not in contact with the fabric 11. In the case shown in Fig. 1, the washing and cleaning system 28 comprises a directed or directable spray system 29 associated with means to feed the washing liquid which acts on the surface of the grinding cylinders 22. In the embodiment shown in Fig. 3, the grinding cylinders 22 cooperate with a movement system which includes a main belt 30 connected to a driving pulley 31 which takes them into rotation during the step when they are in contact with the fabric 11, and a pair of second belts, 32a on the right side and 32b on the left side, closed in a ring which take into rotation the respective groups of cylinders 22, the pile and counter-pile cylinders, in the section where they are not in contact with the fabric 11. The simultaneous rotation of the cylinders 22, including the section where they are not in contact, and of the rotary drum 21, ensures that the jet emitted by the spray system 29 affects the entire circumference of the cylinders 22 during the step when they are not in contact with the fabric 11. This washing and cleaning is necessary in the processing of wet fabrics for the removal of down and fibres which adhere to the surface of the cylinder 22 and which must be removed before the cylinder is taken back into contact with the fabric 11 in order to perform a new grinding action. In the variant shown in Fig. 2, the washing and cleaning is carried out by partly immersing the section of the cylinders 22 where they are not in contact into an impregnation tank 33. The speed of rotation of the drum 21, the speed of free rotation of the cylinders 22 and the size of the tank 33 can be regulated so that the passage of the cylinders 22 in correspondence with the tank 33 causes the whole circumferential surface of each cylinder to be cleaned. The tank 33 may include heating means 135 and/or may cooperate with means to introduce additives and cleaning substances . The rotary drum 21 may be equipped with both clockwise and anti-clockwise rotation with a number of revolutions in a range of between 1 and 150 rpm. The grinding cylinders 22 may also be equipped with clockwise or anti-clockwise rotation, achieving the desired combinations between the two groups of cylinders, the pile cylinders and the counter-pile cylinders, which may rotate in the same direction as each other or in the opposite direction from each other. The speed of rotation of the cylinders is advantageously included in a range of between 0 and 1500 rpm. The rotary drum 21 is housed, in this case, inside a boxlike structure 36 defining a lower in-take zone 38, which also functions as a collection tank for the excess water when working with wet fabric, and closed at the upper part by a cover which can be opened 37. In this case, the lower in-take zone 38 is connected to a water drain 41. The grinding device 10 according to the invention may also be used to process dry fabrics, eliminating the impregnation or damping step. In this case, the path may be that shown with a line of dashes in Figs. 1 and 2, wherein the fabric 11 passes directly from the roller 14 to the roller 17 and then to the inlet drawing roller 18. In the case of dry processing, the upper cover 37 is taken to the open position 37a (shown in Fig. 2 with a line of dashes) to allow the air to circulate, and the lower in-take zone 38 is connected to a conduit 39 connected with an electric aspirator, which is not shown here, in such a way as to create a circulation of air. The variant shown in Fig. 2 also provides to use, at outlet, a dandy roller 40 to grade and regulate the outlet drawing action on the fabric 11 between the drawing and squeezing unit consisting of the cylinders 24 and 120 and the discharge unit 27.

Claims: CLAIMS 1 - Wet grinding method for textile material, applicable to textile material of cotton, wool, synthetic material, elasticised material and similar, used to give to the touch of the fabric particular aesthetic effects such as the ageing effect, the pre-washed effect, the "peach fuzz" effect, the method being characterised in that it provides a preliminary wetting or damping step of the fabric (11) performed upstream of the grinding step, the grinding step being performed by causing the fabric (11) , maintained under tension between a drawing element at inlet (18) and a drawing element at outlet (24), to pass around a plurality of rotary grinding cylinders (22) distributed on the circumference of a rotary drum (21) and lined with material having abrasive properties . 2 - Method as in Claim 1, characterised in that, as it advances from the step when it is sent for wetting or damping to the grinding step, the fabric (11) includes unaccompanied or unguided sections of not more than 3 cm. 3 - Method as in Claim 1 or 2 , characterised in that the wetting or damping step is performed by means of immersion in an impregnation tank (13) . 4 - Method as in Claim 1 or 2 , characterised in that the wetting or damping step is performed by means of spraying liquid on the fabric (11) passing through. 5 - Method as in any claim hereinbefore, characterised in that between the wetting or damping step and the grinding step there is a step to regulate the humidity and/or to eliminate the excess water. 6 - Method as in any claim hereinbefore, characterised in that the wetting or damping step is carried out with liquid at a controlled temperature. 7 - Method as in any claim hereinbefore, characterised in that it includes a step to clean and wash the grinding cylinders (22) in their section which is not in contact with the fabric (11) . 8 - Method as in Claim 7, characterised in that the washing and cleaning step is carried out by means of spraying cleaning liquid directed towards the surface of the grinding cylinders (22 ) . 9 - Method as in Claim 7, characterised in that the washing and cleaning step is carried out by means of partial immersion of the grinding cylinders (22) in an impregnation tank (33) . 10 - Method as in any claim hereinbefore, characterised in that downstream of the grinding step there is a rinsing step. 11 - Method as in any claim hereinbefore, characterised in that downstream of the grinding step there is at least a step to regulate the humidity of the fabric (11) . 12 - Method as in any claim hereinbefore, characterised in that in cooperation with the step to regulate the humidity of the fabric emerging from the grinding step there is at least a drying step. 13 - Wet grinding device for textile material, which can be used on textile material of cotton, wool, synthetic material, elasticised material and similar, used to give to the touch of the fabric particular aesthetic effects such as the ageing effect, the pre-washed effect, the "peach fuzz" effect, the device being characterised in that it comprises means to wet or damp the advancing fabric (11) and arranged upstream of the grinding assembly (19), the grinding assembly (19) comprising a plurality of rotary grinding cylinders (22) distributed on the circumference of a rotary drum (21) , the device comprising at least a drawing element at inlet (18) and a drawing element at outlet (24) of the fabric (11), the grinding cylinders (22) being lined with material having abrasive properties. 14 - Device as in Claim 13 , characterised in that the grinding assembly (19) comprises at least sixteen grinding cylinders (22) distributed on the circumference of the rotary drum (21) . 15 - Device as in Claim 13 or 14, characterised in that the grinding cylinders (22) have a diameter of between 60 and 120 mm. 16 - Device as in any Claim from 13 to 15 inclusive, characterised in that the wetting or damping means comprise an impregnation tank (13) associated with return rollers (15, 17) and/or change-of-direction rollers (16) defining an immersion path for the fabric (11) inside the impregnation tank (13) . 17 - Device as in any Claim from 13 to 16 inclusive, characterised in that it comprises at least a unit to regulate the humidity placed upstream of the grinding assembly (19) and comprising at least a squeezer roller (20) with adjustable positioning. 18 - Device as in any Claim from 13 to 17 inclusive, characterised in that the impregnation tank (13) includes heating means (35) . 19 - Device as in any Claim from 13 to 18 inclusive, characterised in that it comprises means to regulate the drawing action on the fabric (11) associated with the inlet drawing element (18) and/or the outlet drawing element (24) . 20 - Device as in Claim 19, characterised in that the means to regulate the drawing action are load cells. 21 - Device as in any Claim from 13 to 20 inclusive, characterised in that it comprises a rinsing tank (25) arranged at the outlet of the grinding assembly (19) . 22 - Device as in Claim 21, characterised in that it comprises a unit to regulate the humidity, with at least a squeezer roller (120), arranged downstream of the rinsing tank (25) . 23 - Device as in Claim 21 or 22, characterised in that it comprises drying means (26) arranged downstream of the rinsing tank (25) . 24 - Device as in Claim 21, characterised in that the rinsing tank (25) comprises a fabric washing unit (34) . 25 - Device as in any Claim from 13 to 24 inclusive, characterised in that it comprises a washing and cleaning system (28) located outside the rotary drum (21) and cooperating with the surface of the grinding cylinders (22) when they are not in contact with the fabric (11) . 26 - Device as in Claim 25, characterised in that the washing and cleaning system (28) comprises at least a spray element (29) directed and/or directable against the surface of the grinding cylinders (22) . 27 - Device as in Claim 25, characterised in that the washing and cleaning system (28) comprises an impregnation tank (33) in which the section of the grinding cylinders (22) which is not in contact with the fabric (11) is partly immersed. 28 - Device as in any Claim from 13 to 27 inclusive, characterised in that it comprises means to take the grinding cylinders (22) into rotation when they are not in contact with the fabric (11) . 29 - Device as in Claim 28, characterised in that the means comprise at least a chain (32a, 32b) closed in a ring on the circumference defined by the axes of the grinding cylinders (22). 30 - Device as in any Claim from 13 to 29 inclusive, characterised in that it comprises a box-like structure (36) enclosing the rotary drum (21) and including at its upper part a cover (37) and at its lower part an in-take zone (38) connected with an electric aspirator. 31 - Device as in Claim 30, characterised in that the cover (37) has at least an open working position (37a) adopted during the dry grinding step of the fabric (11) .

Inventors: SCORTEGAGNA BRUNO, SCORTEGAGNA, BRUNO
Applicants: LAFER SPA, SCORTEGAGNA BRUNO, LAFER S.P.A., SCORTEGAGNA, BRUNO
Application year: 1998
Main classification: D06C11
IPC codes: D06C11