WO2017187402A1

WO2017187402A1 - Apparatus for processing tubular knitted fabrics

Info

Publication number: WO2017187402A1
Application number: PCT/IB2017/052470
Authority: WO
Inventors: Alessandro ZUCCHI; Stefano LAMPERTI; Leopoldo PETRUZIO
Original assignee: Ferraro S.P.A.
Priority date: 2016-04-28
Filing date: 2017-04-28
Publication date: 2017-11-02
Also published as: ITUA20162970A1

Abstract

The invention relates to an apparatus (100) for treating tubular knitted fabrics, said apparatus (100) comprising: i) a frame (101) that extends in a vertical direction (V) from a base (102); ii) a rope detwisting device (120) mounted in proximity of the top of said frame (101); iii) an inflation device (130) restrained to the frame (101) and comprising a wetting assembly (131) for wetting a tubular fabric (TF) and at least one perforated tube (132) disposed in said base (102) and configured to supply a flow of air towards said tubular fabric (TF), the wetting assembly (131) being arranged under the rope detwisting device (120) in the vertical direction (V) and comprising a duct (131a) that in operation receives therethrough the tubular fabric (TF) in the vertical direction (V); iv) a return roller (103) arranged in the base (102) under said perforated tube (132) in the vertical direction (V); iv) a straightening device (200) mounted on the frame (101) between the wetting assembly (131) and the perforated tube (132) of the inflation device (130). The straightening device (200) comprises a hollow structure (210, 211), e.g. frustoconical shaped, suitable to receive therethrough the tubular fabric (TF) from the wetting assembly (131). The frustoconical structure can be made to rotate about a first axis (A) coinciding with its symmetry axis and can be tilted relative to the vertical direction (V) about a second axis (B) perpendicular to the vertical direction (V).

Description

APPARATUS FOR PROCESSING TUBULAR KNITTED FABRICS

The present invention generally relates to the finishing of knitted fabrics and in particular to an apparatus for processing tubular knitted fabrics, such as e.g. a pre-drying squeezing apparatus.

It is known that tubular knitted fabrics are subjected to dyeing processes after which residues of the liquids employed have to be eliminated in view of the subsequent processing operations. Reference is made in the field to pre-drying by squeezing, which has the purpose of reducing the humidity rate of a fabric from 150-200% to about 50- 70%.

Known squeezing apparatuses for pre-drying tubular knitted fabrics include one or more pairs of counter-rotating cylinders defining one or more corresponding nips through which a wet fabric is made to pass. The counter-rotating cylinders press, i.e. "squeeze", the tubular fabric thereby allowing to eliminate most of the liquids it contains. For this reason, pre-drying apparatuses of this type are also referred to as "squeezing" apparatuses.

A tubular knitted fabric is generally wound or twisted about its axis due to weaving and to the various treatments to which it is subjected, dyeing in particular. Therefore, in order to prevent formation of permanent surface defects such as folds and wrinkles upon passage between the counter-rotating cylinders, squeezing apparatuses typically comprise a rope detwisting device arranged at a certain height from the ground upstream of one or more pairs of counter-rotating cylinders with respect to a feeding direction of the fabric in the vertical direction, more particularly a downward feeding direction. The pairs of counter-rotating cylinder are typically arranged in a base of the squeezing apparatus.

The rope detwisting device receives a tubular fabric and causes it to rotate about its axis in a direction opposite to the winding direction, so as to eliminate folds and wrinkles. In order to facilitate detwisting of a tubular fabric, this is fed to the rope detwisting device from a container arranged on a rotatable rotating platform that is rotated in the same direction of the rope detwisting device.

Known squeezing apparatuses typically also comprise an inflating device for inflating the tubular fabric, which is arranged in the vertical direction between the rope detwisting device and the counter-rotating squeezing cylinders. The inflating device comprises at least one pipe that blows air jets against the outer surface of the tubular fabric while this is moved towards counter-rotating squeezing cylinders. Air enters the tubular fabric through its meshes, thus forming a sort of "balloon" in the vertical direction. Consequently the meshes are stretched, thus allowing to eliminate substantially all residual folds and wrinkles before the fabric is squeezed between the counter-rotating cylinders. Thanks to the vertical arrangement, stretching of the tubular fabric is facilitated by its own weight.

In order to allow to form the balloon of tubular fabric and hence to carry out stretching of its meshes, the inflation device of a squeezing apparatus is typically provided with a wetting assembly arranged close to an outlet of the rope detwisting device. By wetting the meshes of the tubular fabric, e.g. by using water, it is possible to create a fluid veil that prevents air to escape substantially along the whole path of the tubular fabric in the vertical direction.

A squeezing apparatus of the type above for pre-drying tubular knitted fabrics is for example described by Italian patent no. 1280947, according to which an inflated balloon-shaped tubular fabric is received and flattened between two counter-rotating cylinders that carry out squeezing.

Also known are squeezing apparatuses wherein the tubular fabric is spread out while as it proceeds vertically from the rope detwisting device by blowing air in the opposite direction from an inflating device arranged coaxially thereto in the vertical direction. Unlike the apparatus described in the Italian patent no. 1280947, wherein the inflation device operates outside the tubular fabric proceeding towards the counter- rotating squeezing cylinders and air is blown radially or transversely to its feeding direction, in this type of apparatus the tubular fabric coming out from the rope detwisting device and inflated by blowing air in counter-current surrounds the inflation device. Hence, in order to allow the tubular fabric to proceed beyond the inflation device in the vertical direction it is necessary to cut it in the direction of the weft.

A squeezing apparatus of this type for tubular fabrics is for example described by

EP 0708195 Al . Cutting of the tubular fabric in the direction of the weft is carried out at a missing weft. In order to identify the missing weft the apparatus is provided with a centering device associated with the counter-current inflating device. The centering device comprises a pair of oscillating arms restrained to a duct of the inflation device, at the free ends of which motor-driven rollers are mounted. The axes of the motor-driven rollers are arranged parallel to the vertical direction, i.e. parallel to the movement direction of the tubular fabric.

The motorized rollers are brought into contact with the inner surface of the inflated tubular fabric while it is moved in the vertical direction, thus allowing to rotate it about its axis so as to cut it at the missing weft. In order to locate the position of the missing weft, the centering device is equipped with an optical viewing system.

Also known are squeezing apparatuses for pre-drying tubular knitted fabrics wherein the counter-rotating squeezing cylinders do not directly receive the balloon- inflated tubular fabric. The fabric is instead flattened and diverted by one or more rollers for further wetting and inflating steps before the squeezing step.

It is known that as a result of weaving a tubular knitted fabric features a spiral structure. The detwisting and stretching operations of the tubular fabric described above, as well as the related devices and apparatuses, effectively eliminate folds and wrinkles, but have no influence on the possible deformations a tubular fabric will be subjected to when its tubular structure is cut in view of subsequent processing of tailoring operations. In order to reduce the risks of deformation, dimensional stabilization apparatuses are typically employed. These apparatuses comprise widening devices and tunnel-shaped drying assemblies provided with heating means. These devices and assemblies receive a tubular fabric from a squeezing apparatus. However, dimensional stabilization apparatuses do not completely eliminate the risks of deformation.

So-called "straightening" devices integrated in pre-drying apparatuses have been developed in order to try to overcome this problem. The function of the straightening devices is to align the meshes of a tubular fabric horizontally in the portion of the vertical path where it is inflated to form a balloon. It is desired to "straighten" the spiral arrangement of the meshes, thereby allowing to carry out pre-drying and the subsequent finishing operations on a structure that is properly set in view of the subsequent tailoring operations.

Known straightening devices include one or more pairs of idle rollers which are brought in contact with the outer surface of the tubular fabric in the portion where it is inflated so as to form a balloon. The axes of the idle rollers are inclined relative to the axis of the tubular fabric. The inclination angle of the idle rollers is opposite to the inclination angle of the spiral structure of the tubular knitted fabric. Due to the inclined arrangement of the rollers, tangential forces are generated by friction on the surface of the balloon, thereby allowing to align the meshes of the tubular fabric horizontally when is it moved vertically towards the counter-rotating squeezing cylinders.

The squeezing apparatuses having straightening devices can be improved as far as alignment of the meshes of a tubular fabric so as to correct its spiral structure is concerned, which is an object of the present invention. Said object is achieved by a squeezing apparatus whose main features are specified in the first claim, while other features are specified in the remaining claims.

An idea of solution underlying the invention is to make a squeezing apparatus of the above type wherein the straightening device comprises a hollow, axially symmetric structure, for example having a frustoconical shape, adapted to receive through it the balloon-inflated tubular fabric. The hollow, axially symmetric structure is rotatable about a first axis that is its axis of symmetry and is generally parallel to the vertical direction. The hollow, axially symmetric structure is also configured to be inclined relative to the vertical direction by rotating about a second axis perpendicular to the first axis.

Unlike the straightening devices of prior art squeezing apparatuses, which comprise inclined rollers and contact the outer surface of a tubular knitted fabric in the vertical direction only, the straightening device of the squeezing apparatus according to the invention can align the tubular fabric both in the vertical direction and in the circumferential direction thanks to the combination between a rotation of the hollow structure about the first axis and a rotation of the same structure about the second axis, which is perpendicular to the first axis. The resulting straightening effect is therefore much greater than the straightening effect that can be obtained by employing prior art straightening devices with rollers, thus allowing to minimize the risks of deformation of the fabric during the subsequent tailoring operations.

The straightening device of the squeezing apparatus is preferably arranged at the outlet of the wetting assembly, which advantageously allows to carry out horizontal alignment of the meshes of the tubular fabric when this is in the maximum spread out condition and the meshes can be moved more easily relative to one another thanks to the lubricating effect of the water that wets them. This arrangement of the straightening device is advantageous also because it exploits the upstream portion of the fabric structure, which can be rotated or detwisted without distortions due to the fact that it wound like a rope.

According to an embodiment of the invention, the hollow structure has a frustoconical shape comprising a frame and a plurality of arms that are restrained to the frame and extend radially outwards forming an acute angle with the axis of the hollow structure. Each arm comprises a plurality of idle rollers whose respective axes are perpendicular to the axis of the frustoconical hollow structure. The rollers are intended to contact the balloon-inflated tubular fabric. Thanks to this configuration, the hollow structure contacts the tubular fabric at portions having a rather limited surface area. Hence, the meshes may be moved without being damaged by friction.

According to an embodiment of the invention the idle rollers include grooves and ridges that stretch out in circumferential direction and define a corrugated profile that further reduces the contact surface between the rollers and the tubular fabric so as to minimize wear problems caused by friction.

According to a further aspect of the invention, the assembly made up of the inflation device and the straightening device can be applied not only to a squeezing apparatus, but more generally to other apparatuses for processing tubular knitted fabrics such as washing and mercerizing apparatuses, which require straightening operations but not squeezing operations as it is well known in the art.

Further advantages and features of the present invention will be clear to those skilled in the art from the following detailed and non-limiting description of embodiments thereof with reference to the accompanying drawings in which:

- Figure 1 is a side view showing an operating condition of an apparatus according to the invention for processing tubular knitted fabrics; - Figure 2 is a perspective view of a straightening device of the apparatus according to the invention;

- Figures 3, 4 and 5 are a top plan view, a front view and a side view, respectively, of the straightening device of the apparatus according to the invention;

- Figure 6 is a cross-sectional view of the straightening device taken along a plane passing through line VI- VI of Figure 4;

- Figure 7 is a side view showing an operating condition of the straightening device of the apparatus according to the invention.

Referring to figure 1, an apparatus according to the invention for the treatment of tubular knitted fabrics is generally indicated by the reference numeral 100. In the following, reference will be made to a squeezing apparatus for pre-drying a tubular knitted fabric. However, it will be appreciated that the invention is not limited to this particular type of apparatus, but may also be applied to apparatuses for the treatment of tubular knitted fabrics of a different type, such as washing and mercerizing apparatuses, which require straightening operations but not squeezing operations.

The apparatus 100 comprises a frame 101 extending from a base 102 in a vertical direction V perpendicular to the ground. The apparatus 100 further comprises a rotatable platform 110, that is adapted to receive a container C containing a tubular fabric TF from to be processed, and a rope detwi sting device 120 mounted close to the top of the frame 101 and configured to receive and detwist the tubular fabric TF. To this aim, the rope detwisting device 120 comprises in a known way a motorized cylinder 121 provided with a plurality of fins inside its mantle in order to allow the tubular fabric TF to rotate about its axis so as to be detwisted. The rope detwisting 120 also comprises a guide roller 122 that receives tubular fabric TF from the motorized cylinder 121 and directs it to an inflation device 130 of the apparatus 100.

The inflation device 130 is restrained to the frame 101 and comprises in a known manner a wetting assembly 131 configured to receive through it the tubular fabric TF coming out from the rope detwisting device 120 in the vertical direction V after the fabric has been detwisted and to wet it so as to allow to inflate it the form of a balloon. To this aim the wetting assembly 131 comprises a duct 131a extending in the vertical direction V and at least one nozzle 131b for feeding a liquid such as e.g. water from a remote source into the duct 131a. The duct 13 la is closed at the bottom by a diaphragm- shaped seal (not shown) allowing passage of the tubular fabric TF while simultaneously preventing leakage of the liquid used to wet the fabric surface.

With reference to the vertical direction V, the wetting assembly 131 is arranged underneath the rope detwisting device 120 close to the guide roller 122.

The inflation device 130 also comprises at least one perforated tube 132 configured to blow air into the tubular fabric TF. The perforated tube 132 is spaced away from the duct 131a in the vertical direction V and is arranged in the base 102 of the apparatus 100 close to a return roller 103 which directs the tubular fabric TF toward at least one pair of squeezing cylinders 104, 105 that are housed in base 102 as well.

The perforated tube 132 blows air from the outside through the meshes of the tubular fabric TF. The wet tubular fabric is thus spread out forming a balloon extending vertically from an outlet of the duct 131a of the wetting assembly 131 to the roller 103 arranged in the base 102, as shown in figure 1.

As a result of contact with the roller 103, the tubular fabric TF is flattened and proceeds in this configuration towards the squeezing cylinders 104, 105.

In the illustrated embodiment, the tubular fabric TF guided by the roller 103 is drawn to the bottom of the base 102 where it passes through a further wetting assembly and a further inflation device before being received between the squeezing cylinders 104, 105. It will be appreciated that this is not a limiting feature of the invention.

Following the passage between the squeezing cylinders 104, 105, the tubular fabric TF exits from the base 102 along a slide 106 and enters a treatment unit 107 of the apparatus 100, wherein it is further processed with washing liquids, made to pass through a widening device 108, dried and finally received into a folding device 109 which drives it into a container or onto a platform.

According to the invention, apparatus 100 further comprises a straightening device configured to modify or correct the spiral arrangement of the meshes of the tubular fabric resulting from its manufacturing process.

Still with reference to figure 1, the straightening device, generally designated by the reference numeral 200, is mounted on the frame 101 at the outlet of the duct 13 la of the wetting assembly 131 with respect to the vertical direction V. Now referring to figures 2 to 7, the straightening device 200 comprises a hollow structure, for example having a frustoconical shape, adapted to receive through it the tubular fabric TF leaving the duct 131a of the wetting assembly 131. The hollow structure is arranged coaxially to the duct 131a of the wetting assembly 131, thus facilitating passage of the tubular fabric TF through the hollow structure.

As mentioned above, the hollow structure has for example a frustoconical shape widening in the vertical direction V towards the base 102 of the apparatus 100 and comprises e.g. a frame 210 on which a plurality of arms 211 extending radially outwards are mounted.

The widening angle of the hollow, frustoconical structure is such to allow to receive without contact the balloon-shaped tubular fabric TF inflated by the perforated tube 132 of the inflation device 130. Such an widening angle may be a fixed angle, e.g.in the order of 40° as in the illustrated embodiment, or a variable angle obtained by pivoting the arms 211 on the frame 210.

A plurality of idle rollers 212 suitable to contact the balloon-inflated tubular fabric

TF are mounted on each arm 211. The axes of the rollers are perpendicular to the vertical direction V.

The idle rollers 212 have a barrel shape that reduces the contact area with the tubular fabric TF in order to minimize the risk of wear by rubbing during operation of the straightening device 200.

According to the embodiment of the invention shown in the drawings, the idle rollers 212 advantageously include grooves and ridges that develop in a circumferential direction thus defining a corrugated profile. This configuration of the idle rollers 212 further reduces the contact area with the tubular fabric TF, thus contributing to minimize the risk of wear by rubbing.

It will be appreciated that the frustoconical shape of the hollow structure is not a limiting feature of the invention and that it might have other shapes suitable to receive the tubular fabric TF, such as a cylindrical shape having a fixed or variable diameter.

The hollow structure is restrained to a supporting structure 220 of the straightening device 200 and is rotatable about a first axis A that coincides with its own symmetry axis. A motor 230, for example an electric motor, operatively connected to the frame 210, is mounted on the supporting structure 220 so as to cause the frame 210 to rotate about the first axis A. Driving is e.g. carried out by way of a pair of pulleys and a toothed belt, that are respectively shown in the longitudinal and transverse sections of figures 4 and 6.

The supporting structure 220 together with the hollow structure, which in this case is made up of the frame 210 and the arms 211 with the respective rollers 212, can be inclined relative to the frame 101 of the apparatus 100 about a second axis B perpendicular to the vertical direction V, i.e. a horizontal axis parallel to the frame 101. The straightening device 200 further comprises driving means configured to adjust the inclination of the supporting structure 220 relative to the frame 101, i.e. the angle between the first axis A of the frustoconical frame 210 and the vertical direction V.

As shown in figure 5, the driving means may for example comprise a linear actuator 240.

In the illustrated embodiment, the supporting structure 220 is pivoted at the outlet of the duct 131a, for example by way of a frame consisting of two pairs of brackets 131c having a triangular shape fixed to the duct 131a diametrically opposite to each other. Perforated appendages 13 Id are respectively fixed to the brackets 131c. Perforated appendages 220a of the supporting structure 220 are respectively bolted on the perforated appendages 13 Id.

It will be appreciated that this is not a limiting feature of the invention and that the supporting structure 220 might alternatively be pivoted directly on the frame 101 with an equivalent frame and that the linear actuator 240 might be secured between the frame and the supporting structure 220. However, the embodiment shown in the drawings is preferred because it facilitates maneuvering and controlling of the position of the supporting structure 220, as it will be explained in more detail in the following.

During operation of the squeezing apparatus 100, the tubular fabric TF leaving the wetting assembly 131 is received into the straightening device 200 and made to pass through its hollow structure at which it is spread out and assumes the typical balloon shape.

The motor 230 is driven so as to cause the hollow structure to rotate about the first axis A, i.e. around its axis of symmetry. The linear actuator 240 is simultaneously operated so as to cause the hollow structure to rotate about the second axis B, i.e. to tilt it relative to the vertical direction V. The inclination angle may for example be in the order of 5°. Figure 7 shows the above-described operating configuration, wherein the frustoconical structure, more particularly the idle rollers 212 contact the tubular fabric TF.

By rotating together with their respective arms 211 and the frame 210 about the first axis A, the rollers 212 of the hollow structure so inclined relative to the vertical direction V generate on the balloon-inflated tubular fabric TF a plurality of forces displacing its meshes by friction so as to align them in the horizontal direction H while they are moved in the vertical direction V through the straightening device 200. More generally, displacement of the meshes of the tubular fabric TF is caused by the contact in rotation and according to an inclined arrangement with the inner surface of the hollow structure, its shape notwithstanding.

It will be appreciated that the rotation direction of the hollow structure may vary depending on the winding direction of the meshes of the tubular fabric TF, as well as depending on the positive or negative inclination angle between the first axis A and the vertical direction V.

The magnitude and turning direction of the inclination angle can be determined automatically by means of a control system (not shown) of the apparatus 100, for example based on an optical detection of the winding direction of the tubular fabric TF fed into the rope detwisting device 120, which is necessary to adjust the rotation direction of the motorized cylinder 121.

In light of the above, it will be appreciated that unlike the straightening devices of the squeezing apparatuses according to prior art, which employ inclined rollers that contact the tubular fabric TF in the vertical direction V only, the straightening device 200 of the squeezing apparatus 100 according to the invention exerts a contact action not only in the vertical direction V but also circumferentially thanks to the rotation of the hollow structure about the first axis A, as well as thanks to its inclination relative to the vertical direction V by rotating about the second axis B. The resulting aligning effect of the meshes of the tubular fabric TF in the horizontal direction is much greater than what can be obtained by employing known straightening devices having inclined rollers.

Furthermore, compared to the straightening devices of known squeezing apparatuses using inclined rollers, the straightening device 200 of the apparatus 100 according to the invention is arranged at the outlet of the wetting assembly, thereby allowing to carry out alignment of the meshes of the tubular fabric when this is fully stretched and the meshes are more easily movable relative to each other thanks to the lubricating effect of the water that soaks them. As mentioned above, this arrangement is further advantageous because it allows to exploit the upstream portion of the fabric which, being wound in a rope manner, can be rotated without being warped.

The invention has been herein disclosed with reference to preferred embodiments thereof. It will be appreciated that there may be other embodiments relating to the same inventive idea, as defined by the scope of the protection of the claims set forth below.

Claims

1. An apparatus (100) for treating tubular knitted fabrics, said apparatus (100) comprising:

i) a frame (101) that extends in a vertical direction (V) from a base (102); ii) a rope detwisting device (120) mounted close to a top portion of said frame (101);

iii) an inflation device (130) restrained to the frame (101) and arranged under said rope detwisting device (120) in the vertical direction (V), said inflation device (130) comprising a wetting assembly (131) in turn comprising a duct (131a) that in operation receives a tubular fabric (TF) therethrough in the vertical direction (V) and at least one perforated tube (132) arranged in said base (102) and configured to blow a flow of air towards said tubular fabric (TF);

iv) a return roller (103) arranged in the base (102) below said perforated tube (132) in the vertical direction (V);

v) a straightening device (200) mounted on the frame (101) between the wetting assembly (131) and the perforated tube (132) of the inflation device (130), characterized in that said straightening device (200) comprises a hollow structure

(210, 211) arranged coaxially to the duct (131a) of the wetting assembly (131)

and in that said hollow structure (210, 211) is restrained to a supporting structure (220) rotatably about a first axis (A) coinciding with the symmetry axis of the hollow structure, said supporting structure (220) being restrained to the frame (101) about a second axis (B) perpendicular to the vertical direction (V), the straightening device (200) also comprising a motor (230) mounted on the supporting structure (220) and operably connected to the hollow structure (210, 211) so as to allow to rotate it about said first axis (A), and a linear actuator (240) operably connected between the supporting structure (220) and the frame (101) so as to rotate the supporting structure (220) about said second axis (B).

2. An apparatus (100) according to claim 1, wherein the supporting structure (220) is hinged about the second axis (B) at an outlet of the duct (131a) of the wetting assembly (131) and wherein the linear actuator (240) is operably connected between the supporting structure (220) and the duct (131a) of the wetting assembly (131).

3. An apparatus (100) according to claim 2, wherein the hollow structure (210, 211) has a frustoconical shape and comprises a frame (210) and a plurality of arms (211) restrained to said frame (210), said arms (211) extending radially outwards from the frame (210).

4. An apparatus (100) according to claim 3, wherein each arm (211) comprises a plurality of idle rollers (212) the axes of which are perpendicular to the axis (A) of the frustoconical hollow structure.

5. An apparatus (100) according to claim 4, wherein said idle rollers (212) have a barrel shape.

6. An apparatus (100) according to claim 5, wherein said idle rollers (212) comprise grooves and ridges that extend in the circumferential direction and define a corrugated profile.

7. An apparatus (100) according to any one of claims 1 to 6, further comprising a control system operably connected to the motor (230) and to the linear actuator (240) of the straightening device (200) and configured to adjust the rotation direction of the hollow structure (210, 211) about the first axis (A), as well as the angle and the inclination direction of the hollow structure (210, 211) about the second axis (B).

8. An apparatus (100) according to any one of claims 1 to 7, further comprising at least one pair of counter-rotating squeezing cylinders (104, 105), said squeezing cylinders (104, 105) being housed in the base (102) close to the return roller (103).