EQUIPMENT FOR THE PRESETTABLE CALENDERING OF TUBULAR KNITTED FABRIC

Abstract: Equipment for the calendering of tubular knitted fabric (13) which, in the end step of a processing cycle, allows, by means of a cloth expander device (16), a steaming chamber (18) and a flattening, the width of the tubular fabric to be determined and fixed, besides giving the tubular fabric a commercially valid appearance. The presence of a plurality of calenders (19, 20, 26, 27) in series, suitable to be selectively used in engagement with the tubular knitted fabric (13) allows a finishing treatment to be obtained, which is suitable to the individual type of tubular knitted fabric (13) which is sent to the treatment.

Description: The present invention relates to a device for the presettable calendering of tubular knitted fabric. The calendering of the tubular knitted fabric is a finishing operation which is performed during the end stage of the processing cycle, and which has the purpose of drafting the tubular fabric, in general by means of a steaming and flattening between heated cylinders, after previously expanding and overfeeding it. Such an operation allows the width of the tubular knitted fabric to be brought back to the required value, by determining the dimensions thereof, and allows the same tubular fabric to be given a commercially acceptable appearance and touch. Normally, expander devices for the tubular knitted fabric are used, which are equipped with width adjustment systems, based on principles and elements of mechanical character, which require a manual intervention by the operator, and are, e.g., of the sliding-guide type, with blocking by means of screws; when acting is necessary on the width control device inside the tubular knitted fabric, the textile finishing machine must be stopped. It is evident that such a procedure causes time wastes and production losses, an additional use of manpower, machine stops and cost increases, besides the undoubted difficulty of the intervention. Furthermore, single machines or calenders of various types are used, which are different from each other essentially because of the useable cylinder types, as well as due to the different mechanical action they perform on the tubular knitted fabric. Thus, devices exist, which are equipped with drafting calenders, polishing calenders, friction calenders, and so forth. The selection of the equipment to be used depends both on the type of tubular knitted fabric to be processed, e.g., determined by the different fibrous compositions and interlacing patterns of the knitted fabric, and on the finishing effect to be given, so that, according to the different cases, the sequential use is desired of different calender types, so that the need arises for the calender or equipment being used to be replaced. The above, also as a function of the fact that a so-­ structured equipment is installed as a part of a processing line, downstream machines of different types, as, e.g., a dryer. The case frequently occurs furthermore, in which a same article of tubular knitted fabric must the calendered with two different machines, and, hence, by two sequential passages, e.g., by first using a polishing calender equipped with polished cylinder, and then a drafting calender, equipped with cylinders coated with a textile material. Another problem which occurs frequently with some types of tubular knitted fabric, is that of obtaining the required end width of the flattened tubular fabric by means of only one calendering passage. That, due to the deformations the tubular knitted fabric underwent during preceding wet-treatments, such as the mercerization, the bleaching, and/or the dyeing, which caused an excessive decrease in the original width. In such case, both the expansion and the overfeeding of the tubular knitted fabric must be performed gradually and progressively through at least two sequential passages through the calendering machine. It is evident that a double calendering passage, whatever the reason requiring it may be, and both whether it is carried out on the same calendering machine, or on two different calendering machines, causes a considerable decrease in productivity, higher than 50%, and a corresponding increase in production costs. A purpose of the present invention is that of solving all of these problems of calendering variety, of cylinder replacement and of related times for carrying it, so to reduce the costs of production and of machine engagement. A further purpose is that of having a single, extremely flexible, machine, easily fittable to the different knitted fabric which must be calendered, and to the different calendering treatment to be performed on the same knitted fabric. Furthermore, such an equipment must be suitable to be inserted in a treatment facility, so to reduce the production and machine servicing costs, the operating costs and the dead times deriving from the material transport lags. Still a further purpose of the present invention is that of providing an expander device for tubular knitted fabric, which allows interventions of width control to be performed without stopping the same machine, and which may even act during the processing, in an autonomous and continuous way, to correctly adjust the exact width of the tubular knitted fabric, without any manual interventions onto it being necessary. These and further purposes are achieved, according to the present invention, by providing an equipment for the calendering of tubular knitted fabric of the type comprising, on a support frame, an expander device for the tubular knitted fabric being fed, a device for feeding the same fabric towards a steaming chamber, and at least one couple of calendering cylinders for the same fabric, characterized in that on said support frame a second couple of calendering cylinders is furthermore provided, installed sequentially to said at least one couple of calendering cylinders. Preferably, on said support frame, a first and a second calendering units are provided sequentially to each other, with both said first calendering unit and said second calendering unit being provided with said second couple of calendering cylinders installed sequentially to said at least one couple of calendering cylinders. Preferably, said expander device for tubular knitted fabric is of the type comprising one couple of side expander elements provided on related support bars sliding relatively to each other, and adjustable in position, with an elastic thrust element being interposed between said expander elements, and is characterized in that said elastic element is a gas spring hinged onto the two ends of said two support bars, between said two support bars guide means being furthermore provided for said couple of side expander elements during their mutual motion transversal to said tubular knitted fabric. Characteristics and advantages of a calendering device according to the present invention will be better understood from the following exemplifying and non-­ limitative disclosure, which refers to the attached schematic drawings, wherein: Figure 1 is a schematic elevation view of a device according to the invention; Figure 2 is a schematic elevation view of a further device according to the invention; Figure 3 shows an elevation view of an expander device according to the invention, and Figure 4 shows a sectional top view according to path IV-­ IV of Figure 3. As it can be seen from Figure 1, a calendering device comprises a support frame 11, suitable to be inserted, e.g., in a processing facility for tubular knitted fabric 13 which must be calendered, and is fed in a whatever way, e.g., from a dryer outlet (not shown). On said support frame 11 an expander device 16 is installed in a vertical position, for expanding the tubular knitted fabric 13 which is then fed by a feeding device 17 towards a steaming chamber 18. Downstream said steaming chamber 18, wherein also the expander device 16 ends, there are provided, in sequence, a first couple of calendering cylinders 19, e.g., of the type with polished surface, and a second couple of calendering cylinders 20, e.g., of the type provided with a coat of a textile material. On frame 11 at least one return roller 21 is positioned, so to lead the tubular knitted fabric 13 towards the device outlet, towards a whatever collecting unit, or towards a stacking machine. In the just disclosed example of the Figure, the first couple of calendering cylinders 19 used is provided with polished surface in engagement with the tubular knitted fabric exactly as a function of the treated fabric type and of the calendering characteristics to be given. When, either due to a different type of processed fabric, or due to different end characteristics to be possibly given the fabric, intervening on the equipment is necessary, it is enough to disengage the first couple of calendering cylinders 19 with polished surfaces, and subsequently engage the second couple of calendering cylinders 20 having surfaces with a coating of a textile material, or the like. According to the further practical embodiment shown in Figure 2, on a support frame 11 a bobbin 12 is positioned, of a tubular knitted fabric 13 which has to be calendered, so to be made ready for marketing and sale; alternatively, said fabric is supplied from a stack provided on a bench. On said support frame 11 there are provided, vertically, and substantially parallel to each other, both a first calendering unit, generally indicated with 14, and at all similar to that shown in Figure 1, and a second calendering unit, indicated with 15. In Figure 2, in particular the element which constitute the first calendering unit are indicated with the same reference numerals as of Figure 1. A set of return rollers 21, and a compensator element 22, e.g., of the swinging type, and which controls the tension of the tubular knitted fabric 13, are provided on the frame 11, so to feed the tubular knitted fabric 13 to the second calendering unit 15. Said second calendering unit 15 is essentially composed by a set of components at all similar to those of the first calendering unit 14. In fact, downstream the compensator element 22 a further expanding device 23 is provided, which is active on the tubular knitted fabric 13 during its passage through both a further feeding device 24, and a further steaming chamber 25. In sequence, a further first couple of calendering cylinders 26 and a further second couple of calendering cylinders 27, which in this case can respectively be, e.g.: the first couple, with a textile-material coat, and the second couple, with a polished surface; are then provided. The tubular knitted fabric, after passing over a further return roller 28, is subsequently finally extracted through an outlet wind-up cylinder 29, which allows, and cooperates with, the winding up of the same fabric on a wind-up bobbin 30, or delivers it towards a stacking unit. As it appears from the Figure, in the just-disclosed example the first couple of calendering cylinders 19 and the further couple of calendering cylinders 27 used are both of the polished-surface type. This however does not exclude that the various couples of calendering cylinders can be made act on the tubular knitted fabric according to a series of different combinations, so that different characteristics may be obtained in the calendered fabric, e.g., by using both of said couples with cylinders of the type coated with a textile material, and/or selectively using first a couple with polished surfaces, and subsequently a couple with surfaces coated with textile material, and/or vice-versa. This full range of combinations, together with the possibility of variation of all of the other operating parameters, i.e., increase in operating speed of the feeding devices 17, 24 with over-feed, variation in steam amount in chamber 18, 25, allow many calendering effects to be obtained, such to fit to a wide variety of fibres and of weaving interlacing patterns. It should not be neglected that these interventions for functional changes on the equipment of Figure 1, as well on that of Figure 2, are simply performed by means of the shifting, and the consequent engagement and disengagement of the various couples of cylinders, with extremely short operating times, if not nearly zero times, which allow the production costs to be considerably reduced. A further, surely very favourable advantage, in that on one single calendering equipment only, it is possible to perform at least two different calendering operations by means of one passage only. A further advantage is the elimination of cylinder replacements, or of the necessary presence of a plurality of different cylinder machines selectively insertable on line according to the requirements. The positioning inside the equipment, in the reverse sequence, first of cylinders with surfaces coated with a textile material, and then of cylinders with polished surfaces, shapes of course an equipment which is inside the protection scope of the present invention. A calendering equipment according to the present invention as shown in Figure 2 is, i.e., endowed with the advantageous characteristics of allowing, on one single operating line, a double expansion and a double feed or progressive overfeed of the tubular knitted fabric to be obtained. Such an innovative operating concept enables hence the textile finisher to comply with the many needs he must confront with, and to solve at the same time the production and financial problems arising from the need for a plurality of sequential calendering passages. Preferably, an expander device for tubular knitted fabric indicated with 16 or 23 in Figures 1 and 2 can be advantageously accomplished as shown in Figures 3 and 4. Said device is generally indicated with 111 and is generally positioned on a support frame 112 of a textile finishing machine (not shown), supported between feed devices 113, e.g., motor-driven rollers, on which a tubular knitted fabric, schematically shown in 114, runs. The expander device 111 is constituted by two side expander elements 115, each constrained to a related support bar 116, with the two support bars 116 being sliding relatively to each other. Each support bar 116 has, on its side opposite to the other bar, a couple of guide grooves 117 provided inside the thickness thereof, within which related guide rollers 118 are engaged, which are always positioned fixed on the opposite end portion of the other bar 116. The two bars 116 can thus slide on each other, up to come to a mutually superimposed position, as shown by the position, in chain in Figure 3, of the right-hand expander element 115. Due to such a movement, the two side expander elements 115, in their position of maximum width as indicated by La , can approach each other up to the position of minimum width, as indicated by Lc , the relevant stroke length being indicated by C . An elastic element 119, such as a gas spring, has its ends hinged in 120 and 121 onto respectively the two bars 116. The gas spring 119, of known type, is constituted by a small cylinder 122 containing a pressurized gas, and a stem 123 which enters one of the two base ends of the cylinder. The two free and opposite ends of the cylinder 122 and of stem 123 are each fastened, as said, to its own bar 116, respectively in 120 and 121. Each side expander element 115 bears two return wheels 124, slightly protruding from it outwards, on which a belt element 125 winds round, which is used for accompanying the tubular knitted fabric. Furthermore, in correspondence of a lower inlet portion 126 of each side expander element 115, which has a shape convergent towards the interior of the device, two wheels 127 are furthermore provided, which cooperate to accompany the tubular knitted fabric 114 during the step of slipping thereof on the expander device 111 inbetween the motor-­ driven wheels 113. It should be observed that on the support frame 112 slots 128 may be provided, inside which the drive shafts 129 for the motor-driven rollers 113 can slide, so to allow the distance between the centres of the same rollers to be modified, to fit to varying widths of the tubular knitted fabric 114. The operating way of such an expander device 111 can be easily understood. In its working position, the expander device for the tubular knitted fabric is housed between the motor-driven wheels 113 of the finishing machine, in such a way that each of them comes to respectively adhere to the lower wheel 124 and to the upper wheel 127 close to said motor-­ driven wheels 113 of each expander element 115. Such motor-driven wheels 113 have furthermore the possibity of performing a lateral or transversal movement, so to be able to approach each other, or to get spaced apart from each other, by sliding inside the slots 128. When the two side expander elements 115 of the expander device are in their position of maximum width La , the stem 123 of the gas-spring 119 is in its extracted position from the cylinder 122, and the gas inside the same cylinder exerts on it a thrust force Fa which makes the two side expander elements 115 to adhere to the motor-driven wheels 113. Due to the transversal movement of the two motor-­ driven wheels 113, the side expander elements 115 of the expander device approach progressively each other, making the two bars 116 slide on each other, by being guided by the guide rollers 118, and thus compress the gas spring 119 due to stem 123 entering the cylinder 122. When the position of minimum width Lc is reached, the gas inside the cylinder 122 applies to the stem 123 a thrust force Fc , which keeps the side expanders 115 always adhering to the motor-driven wheels 113 and allows them to follow them, in case of a contrary transversal movement, in the direction of opening of the tubular knitted fabric expander device. The transversal movement of the motor-driven wheels 113 is electrically controlled by the operator attending the finishing machine, in accordance with the different fabric widths, thus causing the continuous and progressive opening and/or closure of the expander device 111, without any need for stopping the finishing machine, or for any manual interventions. As compared to the width control devices known from the prior art, accomplished, e.g., by means of spiral springs or pneumatic pistons, a so-structured expander device is endowed with advantageous innovative and inventive characteristics, which can be summarized as follows: - possibility of supplying an initial preload Fa , when the gas spring is in its released position, determined by the initial pressure of the gas contained inside the cylinder, with thereby in no way being the useful length of stroke C affected; - very long useful stroke "C" of the gas spring, which reaches values as high as 40% of the length of the gas spring when this is in its released position, without causing any excessive increases in the thrust force, generally indicated with F ; - change in thrust force between the released position ( Fa ) and the compressed position ( Fc ) of the gas spring limited to only 15-20%, which guarantees uniformity in the gas spring response, in any, even extreme, or intermediate positions thereof; great structural, operative and application simpleness, with no need for connection to external power supplies, such. as, e.g., compressed air.

Claims: 1. Equipment for the calendering of tubular knitted fabric of the type comprising, on a support frame (11), an expander device (16, 111) for the tubular knitted fabric (13, 114) being fed, a device (17) for feeding the same fabric towards a steaming chamber (18), and at least one couple of calendering cylinders (19) for the same fabric, characterized in that on said support frame (11) a second couple of calendering cylinders (20) are furthermore provided, installed sequentially to said at least one couple of calendering cylinders (19). 2. Calendering equipment according to claim 1, characterized in that said at least one couple of calendering cylinders (19) are of the type with polished surface, and said second couple of calendering cylinders (20) are of the type with a coat of textile material. 3. Calendering equipment according to claim 1, characterized in that said at least one couple of calendering cylinders (19) are of the type with a coat of textile material, and said second couple of calendering cylinders (20) are of the type with polished surface. 4. Calendering equipment according to claim 1, characterized in that on said support frame (11) a first (14) and a second (15) calendering units are installed, sequentially to each other, with both of said first and said second calendering units (14, 15) comprising said at least one couple of calendering cylinders and said second couple of calendering cylinders (19, 20, 26, 27). 5. Calendering equipment according to claim 4, characterized in that said first and second calendering units (14, 15) are arranged on said support frame (11) vertically and parallelly to each other, between said two groups (14, 15) return rollers (21) being provided, besides a compensator element (22). 6. Calendering equipment according to claim 4, characterized in that downstream said second calendering unit (15) at least one wind-up cylinder (29) is provided, which cooperates for the purpose of winding up again said tubular knitted fabric (13) on a related wind-up bobbin (20), or of delivering the fabric towards a stacking equipment. 7. Expander device for tubular knitted fabric, in particular for a calendering equipment, suitable to be inserted inside a tubular knitted fabric (13, 114) of the type comprising a couple of side expander elements (115) installed on related support bars (116) sliding relatively to each other and adjustable in position, with an elastic thrust element (119) being interposed between said expander elements (115), characterized in that said elastic element (119) is a gas spring hinged at its two ends (120, 121) onto said two support bars (116), with between said two support bars (116) guide means (117) being furthermore provided, for the purpose of guiding said couple of side expander elements during their mutual movement crosswise to said tubular knitted fabric. 8. Expander device according to claim 7, characterized in that said guide means for said side expander elements (115) are respectively a couple of guide slots (117) provided on mutually opposite sides of said support bars (116), inside which guide rollers (118) enter slidingly, which are constrained to the end of the opposite bar. 9. Expander device according to claim 7, characterized in that each of said side expander elements (115) bears two return wheels (124) on which a belt element (125) winds round, said return wheels (124) and said belt element (125) being slightly protruding from said side expander elements (115) outwards. 10. Expander device according to claim 7, characterized in that each of said side expander elements (115) has, in a lower entrance portion thereof, a shape converging towards the interior of said device, and supports two wheels (127) which cooperate to accompany said tubular knitted fabric during the inserting step thereof.

Inventors: DALLA VECCHIA, GINO
Applicants: SPEROTTO-RIMAR S.P.A.
Application year: 1987
Main classification: D06C5
IPC codes: D06C5