RAISING OR NAPPING MACHINE

Abstract: A raising-napping machine comprises a drum composed of a plurality of satellite rollers (7) capable of being driven at a peripheral speed that is adjustable about the drum's peripheral speed, said rollers (7) being disposed at regular intervals along the drum's circumference. The outer cylindrical surface of the drum supports the fabric (12) travelling along at least a portion of the rotating drum's circumference. The machine has means driven by a single regulation actuator (13) capable of modifying the radial position of said satellite rollers (7) with respect to the drum's axis for increasing or decreasing the spacing between adjacent satellite rollers (7) along said drum's circumference.

Description: RAISING OR NAPPING MACHINE FIELD OF THE INVENTION The present invention relates to a raising process of a woven or knitted fabric or a napping process of a woven or knitted fabric or of a composite fabric, for example a resinated cloth or similar continuous sheet material, with an improved control of the action performed by raising or napping satellite rollers of a rotating drum and a universal raising-napping machine. BACKGROUND OF THE INVENTION The raising process for lifting the pile of the yarn (woof and warp) of a woven or knitted fabric is known form ancient times and is performed nowadays for producing an extremely vast range of fabrics having peculiar characteristics. Blankets with enhanced thermal characteristics versus weight and so-called "pile" garments of fashionable look are few examples of textile products that are obtained through a raising treatment of a base fabric. However, raising and/or napping treatments of woven and knitted fabrics as well as of composites formed by resin films coupled to a woven fabric to produce artificial leather substitutes, are widely used in many productions in order to confer to the fabric a characteristic felted aspect and/or a certain tactile characteristic, beside conferring for example to a certain fabric improved transpiration, absorption and/or thermal insulation characteristics. Modern universal raising machines are essentially composed of a rotating drum formed by a plurality of satellite or peripheral rollers that are driven in rotation at an adjustable speed in order to vary their peripheral speed by a small fraction above or below the peripheral speed of the drum and therefore of the fabric running over the satellite rollers. The outer cylindrical surface of the satellite rollers is covered with appropriate raising or napping fillets (coverings) chosen in function of the type of treatment to be carried out and of the characteristics of the fabric to be treated. For example, in case of a pile raising treatment of a woven cloth, the satellite rollers are covered with an appropriate raising covering, typically in the form of a tape supporting a plurality of metal needles having their points bent through a certain angle and having a population density and elastic characteristics chosen in function of the particular type of woven or knitted fabric to be treated. The orientation of the bent points of the needles of each raising roller may be such as to determine an angle of incidence functionally opposed to the direction of advancement of the fabric (counterpile action) or in the same direction of advancement of the fabric (pile action). The action of the single raising rollers may be of the same type or of an alternate type, for example of the type: ... pile/counterpile/pile/counterpile/ ... . The needles of few of the peripheral raising rollers may also have a blunt, ball or mushroom-shaped end instead of a point end for exerting a specific felting action of the pile raised by the other rollers of the drum and so forth. In these machines, in an outer satellite position as referred to the rotating drum, there are at least an inlet and an outlet guiding rollers for guiding the fabric to be treated over a certain arc of circumference of the drum, which in the case of a single pair of inlet and outlet rollers, may be of about 270° or even greater. The same (universal) machine, may also be used for slightly different purposes than pile raising and specifically for napping a certain fabric to produce a superficial finish typical of the flesh-side of a natural leather or for conferring to a woven cloth, for example a cotton cloth, a peculiar tactile characteristic. In order to do that, it is generally sufficient to substitute the coverings of needle fillets with abrasive coverings on the outer cylindrical surface of the satellite rollers of the drum. The abrasive coverings may be in the form of an abrasive paper tape of a given granulometry that can be readily wound over the rollers. Clearly the mode of operation of the machine is similar whether the satellite rollers are equipped with needle type, raising fillets or with abrasive napping fillets. In the following description, reference will be made primarily to a machine equipped with pile raising needle fillets, being understood that the same considerations would be valid mutatis mutandis also in the case the needle pile raising fillets be substituted with another kind of fillets, for example with an abrasive tape of a certain granulometry for napping a cloth or a composite fabric, for example an artificial composite leather substitute. These machines are well known and widely used, in different configurations, in the textile industry. The pile raising or napping action exerted by the satellite rollers of the rotating drum of the machine may be such as to produce a certain permanent linear elongation of a fabric and a corresponding shrinking of its width (or height). Therefore, the guiding rollers of the fabric to be treated must be provided with organs for recovering the elongation eventually produced by the raising or napping process. In case of a cloth to be raised, in order to avoid accidental tearing of junction seams of the fabric upon the passage of a seam over the pile raising drum, dedicated mechanisms detect the arrival of a junction seam and automatically revert momentarily the speed or rotation of the satellite raising rollers to the so-called "zero-point" speed, that is to assume a peripheral velocity identical to the peripheral velocity of the drum (and therefore of the fabric running thereon), in order to momentarily interrupt the pulling action exerted by the needles upon the passage over the drum of the seam. The extremely critical character of the regulation of the relative peripheral velocity of the raising rollers as referred to the so-called "zero-point" is well known, as well as the choice of the type of raising fillets (configuration density and elastic characteristics of the needles) in producing a certain result on a fabric in a most satisfactory way. An excessive "grip" (interference) of needles acting in a counterpile mode may excessively weaken or even ruin a cloth, by decisively tending to tear off the pile in an excessive manner, while a too weak "grip" may fail to produce a satisfactory result. Mutatis mutandis, similar considerations may also be made in the case all the raising rollers be exerting a pile-mode action, and also in the case when the action of the raising rollers is of an alternate type, namely: counterpile/pile/counterpile/pile and so forth. Another important aspect of this type of treatments is represented by a more or less disuniform effectiveness of the raising or napping rollers, due to a disuniform tension of the fabric running over the rotating drum. This may depend on a more or less marked engagement of the needles or of the abrasive particles of the raising-napping satellite rollers along the entire arc of engagement of the fabric with the drum, as a consequence of successive elastic tensioning followed by relieving of the fabric occurring along the arc of circumference over which the fabric runs over the drum. This tends to reduce or nullify completely the raising of napping performance of the rollers in certain zones of the arc of contact of the fabric with the drum, with an overall decline of the yield of the process, as referred to the result obtained with a single passage of the fabric over the treatment drum. The observation of these phenomena has led to the development of optimization techniques as the one characterized by engaging the fabric on the drum repeatedly and for shorter arcs of circumference, by employing two or more pairs of guiding (inlet and outlet) rollers and by appropriately modifying the fabric handling mechanisms of the machine. Such an improved process and relative raising machine are described in prior EP-A-0088431-B2, the description of which is herein incorporated by express reference. In case of woven or knitted fabrics with yarn and overall strength characteristics particularly critical if referred to the peculiarity of the raising-napping process described above, the above-noted problems of regulating the action of the raising-napping rollers becomes extremely serious. Often these problems may be overcome or lessened in a significative way only by "subregulating" the raising-napping action of the rollers of the drum and by performing a repeated number of passages of the cloth until a satisfactory raising-napping effect is obtained, without excessively weakening or ruining the base fabric. Of course certain results may be reached only with an accompanying heavy loss of productivity and therefore with a relatively high cost. Also under substantially noncritical conditions, in terms of quality and strength of the base fabric to be treated, it is often difficult to quickly attain an optimum regulation of the relative velocity of the raising-napping rollers and therefore the definitive regulation represents almost invariably a compromise between quality of the result of the treatment and pro¬ ductivity, case-by-case privileging one or the other. These difficulties derive from the fact that for a certain raising or napping fillet fitted over the rollers, the only remaining regulation parameter is that of fixing a certain optimal differential between the speed of the fabric, that is the peripheral velocity of the drum, and the peripheral velocity of the raising or napping rollers. Other important parameters, for example the separation distance (pitch) between adjacent rollers, being practically fixed or difficult to vary from the design ones. SUMMARY OF THE INVENTION It has now been found and represents the object of the present invention a way to overcome such inalterability of the geometric configuration of the raising or napping drum by realizing a machine, the diameter of the drum of which can be adjusted in function of the type of treatment to be done and above-all in function of the type of fabric or material to be treated, by modifying the radial position of all the satellite rollers so as to increase or decrease the separation distance among the roller that is, the distance between adjacent successive points of grip and support of the fabric or similar material over the cylindrical surfaces or more precisely over the fillets fitted over the satellite rollers. The machine of the invention eliminates such a hardly modifiable design choice by allowing a quick adjustment of this parameter that in the case of treatments carried out on fabrics or materials having a marked difference in weight may become extremely critical or anyhow difficult to compensate through the adjustment solely of other parameters. According to a preferred embodiment of the invention, each satellite roller is rotatably and mounted on two "eccentric" hubs or bushes, respectively installed in dedicated coaxial holes of the two support flanges (commonly referred to as "stars") of the satellite rollers that form the drum. By "eccentric" hub or bush is herein intended a rotatably mounted element having a hole or a recess housing a ball or roller bearing for rotatably supporting one end of a satellite roller that is offset with respect to the axis of rotation of the element. Each bush can be rotated within the hole of the "star" flange and is provided with a toothing that engages with the toothing of an idle or free stepped gear wheel mounted on the shaft of the drum. Each idle stepped gear wheel is provided by at least another toothing that engages with a gear of a regulation shaft. The regulation shaft is rotatably sustained in a support, solidly mounted on the shaft of the drum, and may be driven by an electric motor or by any other equivalent actuator. By rotating the regulation shaft, all the eccentric bushes that support the satellite rollers may be rotated synchronously and the eccentricity of the axis of the bearings of each raising roller determines a radial shift of the axis of all the satellite rollers. In other words, by rotating the bushes in one direction or in the opposite direction an expansion or a contraction of the effective drum's diameter and a corresponding increase or decrease of the distance between adjacent roller, along the drum's circumference are obtained. The separation distance between adjacent rollers may be varied between about 5 nm and about 30 nm, thus permitting a sensible modification (optimization ) of the napping raising action. BRIEF DESCRIPTION OF THE DRA WINGS The various aspects and advantages of the this invention will become even clearer through the following detailed description of an important embodiment of the invention and by referring to the annexed drawings, wherein: Figure 1 is a schematic cross sectional view of the drum of a raising- napping machine, made according to the present invention; Figure 2 is a simplified schematic, partially sectioned plan view of the machine's drum. DESCRIPTION OF A PREFERRED EMBODIMENT With reference to the figures that show for purely illustrative purposes one of many possible forms of realization of the invention, the drum of a raising-napping machine is indicated as a whole with 1. The drum is constituted by a hollow shaft 2 horizontally supported on the bearings 3 and 4. Two flanges or stars members, respectively 5 and 6, support a plurality of raising-napping rollers 7 mounted on ball bearings 8 and 9 that, according to the invention, are set in respective eccentric bushes B1 , B2, ..., B3, B4, which are rotatably installed in holes or housings distributed along a peripheral circumference of the two flanges 5 and 6. The drum may be rotated by a belt transmission employing a drive pulley or through a demultiplied electric motor (gearmotor) 11, while each satellite roller 7 (raising or napping roller depending on the fillet used) is provided with its own drive pulley 10. As may be observed in the cross section of Fig. 1, the fabric or the continuous ribbon of tape material to be treated 12 is guided over the revolving drum 1 by a pair of guide rollers, namely: an inlet 28 and outlet roller 29, respectively. Some machines are able to reverse the direction of motion. By referring hereinbelow for simplicity of description to the case of a raising treatment performed on a cloth, the arc of circumference of the drum that is engaged by the running fabric may also be different (smaller) than the one shown in the example of Fig. 1 , where it is approximately equal to 270°. Two rotating brushes, respectively 30 and 31, are fitted in a zone of the revolving drum that is not engaged by the fabric 12. The two rotary brushes strip the residues of pile that are inevitably teared off by the needles of the raising rollers. The pile residues are continuously sucked into the mouth of a vacuum hood or conduit of pile fragments a suction system (not shown in the figures). As it is well known to a skilled person, by acting on the belt transmission that drives to rotation the various raising rollers 7, their peripheral speed may be varied above or below the speed of the fabric 12, that is, the tangential peripheral speed of the drum 1 (a reference condition commonly referred to as "zero-point" condition), in order to exert a raising or a buffing action on the fabric. In implementation of the invention, the machine is equipped in such a way to allow to synchronously vary the radial position of all the raising rollers 7 through a single control actuator. The eccentric bushes B1, B2 B3, B4, that house the ball bearings 8 and 9, have the rotation axis Ac of the respective roller 7 offset in respect to the rotation axis Ab of the two supporting bushes. Because of this, by rotating the supporting bushes, the radial position as referred to the drum's axis of the rotation axis Ac of the raising rollers 7 increases or decreases. The relative distance between the two axes Ac and Ab (eccentricity) determines the variation range of the radial position of the axes of the satellite rollers, as shown in Fig. 1. As illustrated in Fig. 1, the "expansion" or "contraction" of the drum's circumference determines a "getting closer" or a "getting farther apart" of the satellite rollers. As a consequence, the leaning points (lines of contact) of the fabric 12 over the rotating drum may become closer or be more spaced apart by varying the spacing between adjacent rollers 7. In practice the leaning configuration of the fabric over the raising rollers may be considered represented by polygonal line, the segment length of which can be reduced or increased. This has a marked influence on the "engagement" between the raising-napping fillet set on the cylindrical surface of the satellite rollers 7 and the cloth 12. Relatively lightweight fabrics are easier to treat by reducing the distance (the length of the segment of the ideal polygonal line) between the points of engagement with the fillets of adjacent satellite rollers 7, whereas in the case of relatively heavy fabrics, the raising or napping action may be accentuated by expanding the drum's circumference that is, by increasing the distance among the leaning lines (engagement) with the fillets of adjacent satellite rollers. The synchronous rotation of all the eccentric bushes B1, B2, ..., Bn-1, Bn is actuated by a single device that as shown in the illustrated embodiment may be an electric gearmotor 13 mounted on an appropriate support 14 that is fixedly assembled on the drum's shaft 2. The motor 13 may be drivable through a multiwire cable passing inside the hollow shaft 2 of the drum and suitably connected through a plurality of electric brushes 15 to an external command console. The motor 13 drives a shaft 16, having two gears 17 and 18, respectively, that engage with the toothing 19 and 20 of the two idle stepped gear wheels 21 and 22, mounted on bearings 23 and 24 on the drum's shaft 2. The two idle stepped gear wheels 21 and 22 have a toothing, 25 and 26 that engages with the toothing 27 of each bush B1 , B2, .... B3, B4, ... . In this way, through the command of the gearmotor 13, all the eccentric bushes that carry the bearings of the satellite rollers 7 may be rotated in one direction or in the opposite direction simultaneously, for expanding or contracting the drum, as depicted in Fig. 1. The idling rollers, not shown, that normally maintain a correct tension of the running fabric 12, are naturally capable of automatically maintaining a correct constant tension of the running fabric 12 following either a contraction or an expansion of the effective diameter of the rotating drum. Conversely, as schematically shown in Fig. 1 , the radial position of the two rotary brushes 30 and 31 , must be adapted to the eventual expansion or contraction of the drum's effective diameter in order to perform an effective cleaning action on the fillets of the satellite rollers 7. Such a "tracking" of the position of the rotary brushes rollers 30 and 31 may be implemented through any automatic positioning device, whose realization does not involve any difficulty for any ordinarily skilled technician. Although a particularly preferred embodiment of the invention, involving the use of "eccentric" bushes and a regulation transmission of the radial position of the satellite rollers employing a pair of idle stepped gear wheels has been described, it is evident that other regulation means, using a mechanical or pneumatic transmission can be satisfactorily employed in an alternative embodiment of the invention.

Claims: C L A I M S 1. A raising-napping machine comprising a drum composed of a plurality of satellite rollers capable of being driven to a peripheral speed that is adjustable about the drum's peripheral speed, said rollers being disposed at regular intervals along the drum's circumference and on the outer cylindrical surface of which leans the fabric travelling along at least a portion of the rotating drum's circumference, characterized in that it comprises means driven by a single regulation actuator capable of modifying the radial position of said satellite rollers in respect to the drum's axis for increasing or decreasing the spacing between adjacent satellite rollers along said drum's circumference. 2. The machine according to claim 1 , characterized in that each of said satellite rollers is rotatably supported on bearings set in two bushes, mounted respectively in two flanges of said drum, said bearings being set in an eccentric position in respect to the rotation axis of said bushes; each of said bushes having a toothing geared to an idle stepped gear wheel mounted on the shaft of said drum and having a second toothing engaged with a gear of a regulation shaft rotatably mounted on a support fixed on said shaft of the rotating drum and driven by said single actuator. 3. The machine according to claim 2, characterized in that said single actuator is an electric gearmotor. 4. The machine according to claim 1 , characterized in that the separation distance between the outer cylindrical surfaces of adjacent satellite rollers may be adjusted between approximately 5 millimeters and approximately 30 millimeters. 5. The machine according to claim 1, characterized in that it comprises means capable of adjusting the radial position of at least a rotary brush used for cleaning the outer surfaces or fillets of said satellite rollers in function of the variation of the radial position of said satellite rollers.

Inventors: LAMPERTI ANTONIO, LAMPERTI, ANTONIO
Applicants: LAMPERTI ANTONIO, LAMPERTI, ANTONIO
Application year: 1996
Main classification: D06C11
IPC codes: D06C11