FLUID-DRIVEN APPARATUS FOR FEEDING A FABRIC IN A PROCESS TUMBLER

Abstract

A fluid-driven apparatus continuously feeds fabric in open-width form. The apparatus is associated in combination with a tumbler processing the fabric. The apparatus includes a tubular duct, with a substantially rectangular transversal cross section, has boundary walls which delimit an internal cavity inside the duct. A manifold supplies gaseous fluid into the duct through an opening formed in the top or bottom wall of the duct. Ports for the fluid extend in a direction longitudinal to the duct, into and out of the cavity. The manifold abuts the opening to divide the duct into two distinct stretches delimited by the manifold and by the ports. The manifold includes a diverter for selectively directing the fluid towards one of the stretches of the duct. A portion of one of the duct stretches is divergent in shape, with a transversal cross section increasing from the manifold to the respective end port.

Claims

1. A fluid-driven apparatus for feeding a fabric in open-width form and continuously, the apparatus being associated in combination with a tumbler processing the fabric, the apparatus comprising: a tubular duct with substantially rectangular transversal cross section, having boundary walls which delimit an internal cavity inside the duct; a manifold for supplying gaseous fluid into the duct through at least one opening formed in a top wall or a bottom wall of the duct; ports for passage of the fluid in a direction longitudinal to the duct, into and out of the cavity; the manifold being abutted against the at least one opening, at a position to divide the duct into two distinct stretches delimited by the manifold and by one of the ports, respectively; the manifold being equipped with diverting means for selectively directing the fluid towards one or the other of the stretches of the duct; wherein at least one portion of at least one of the stretches of the duct is divergent in shape, with a transversal cross section which increases in size from the manifold to the respective end port.

2. The apparatus according to claim 1, wherein divergence of said portion of at least one of the stretches is obtained by inclining only the top wall relative to the bottom wall.

3. The apparatus according to claim 1, wherein at least one of the stretches is entirely divergent in shape, with increasing transversal cross section.

4. The apparatus according to claim 3, wherein both the stretches are entirely divergent in shape, with increasing transversal cross section.

5. The apparatus according to claim 1, wherein the divergent shape has an angle of divergence not greater than three sexagesimal degrees.

6. The apparatus according to, claim 1, wherein the fluid is thermally conditioned.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the drawings:

[0015] FIG. 1 is a schematic longitudinal cross section of a fabric feed apparatus known to operators in the industry;

[0016] FIG. 2 schematically represents the typical operation of the apparatus of FIG. 1;

[0017] FIG. 3 is a schematic longitudinal cross section of an apparatus made according to this invention;

[0018] FIG. 4 schematically represents the typical operation of the apparatus of FIG. 3 in a scaled-up longitudinal cross section.

EMBODIMENTS OF THE INVENTION

[0019] With reference to the accompanying drawings, FIGS. 1 and 2 illustrate a prior art pneumatic apparatus for feeding a fabric in a tumblernot illustratedwhich processes fabrics in open-width form and continuously.

[0020] FIG. 3 shows a fluid-driven apparatus 1 of the kind shown in FIGS. 1 and 2, for feeding a fabric 7 and which essentially comprises: a tubular duct 2; a manifold 14 for supplying flows 3,4 of gaseous fluid into the tubular duct 2; and flow diverting means, embodied in this case by two flap valves 8 associated with the manifold 14 and contained therein.

[0021] More specifically, the duct 2 has a tubular profile with a substantially rectangular cross section and is provided with boundary walls at the top and bottom (11a,11b) and sides (not illustrated) delimiting an internal cavity 12 inside the duct.

[0022] At opposite open ends of it, the duct is also provided with ports 9 and 10 for the passage of the fluid in the form of flows 5,6 directed longitudinally, one into and the other out of the duct 2.

[0023] Half way along it, the tubular duct 2 is provided with four further openings 13 formed in opposite pairs, passing through the top and bottom walls 11a,11b, of the duct 2. Connected to the openings 13 of the duct 2 is the manifold 14 which, thanks to its positionsubstantially half way along the duct 2divides the latter into two component stretches 15a,15b of equal length, one of which is delimited by the manifold 14 and the port 9 and the other by the manifold 14 and the port 10.

[0024] According to the invention, at least one of the two stretches 15a,15bor preferably both of themis divergent in shape, with a transversal cross section which increases in size from the manifold 14 to the port 9 or 10 associated with the stretch 15a or 15b of the duct 2.

[0025] Small angles of divergence 16 have been found to be surprisingly optimal. Angles not greater than three sexagesimal degrees are preferable.

[0026] In FIGS. 3 and 4, the divergence of the stretches 15a,15b of the duct 2 is advantageously obtained by inclining only the top wall 11a relative to the bottom wall 11b. This solution has proved surprisingly more effective than the solution in which the divergence is obtained by inclining the bottom wall 11b and keeping the top wall 11a horizontal or by inclining both of the walls 11a,11b at an angle to the horizontal. In a further embodiment, each of the two stretches 15a,15b of the duct 2 has a constant cross section in a first portion of it adjacent to the manifold 14 and a divergent shape with increasing cross section in the second portion of it.

[0027] In use, the operation of the apparatus 1 may be described with reference to FIG. 4. As may be inferred from FIG. 4, the two air flows 3 and 4if necessary, thermally conditioned and coming from a central preparation plantcome through the manifold 14 from different directions normal to the duct 2. Inside the manifold 14, the two air flows 5 and 6 are intercepted by the flap valves 8 and are diverted into the cavity 12 of the duct 2, one above the fabric 7 and the other below it, so as to flow through one of the two stretches in the same direction: in the case illustrated, the stretch 15b of the duct 2. By effect of the two flows 6, the fabric 7 downstream of the manifold 14 is pushed by the two fluid flows 6. The pushing action causes the fabric 7 to be curled and creased, whilst upstream of the manifold 14 in the stretch 15a, it is pulled and sucked into the cavity 12 together with the gaseous fluidoutside the duct 2through the port 9 associated with the other stretch 15a of the duct 2.

[0028] It should be noted that the divergence of the stretches 15a and 15b, although only slight, produces a plurality of highly synergic, useful effects which allow the fabric 7 to be pneumatically supported and fed along the duct 2.

[0029] In effect, as is clear from FIG. 4, the fabric 7 just downstream of the manifold 14, although it starts curling, does not obstruct the flows 6 of gaseous fluid needed to move it. On the contrary, a virtuous circle is created in this zone of the apparatus 1, because: thanks to the divergence, the air flow 6 is kept relatively constant and able to support the fabric 7; consequently, the fabric becomes less curled and moves more rapidly than it does in conventional apparatuses, where the stretches of duct are provided with equidistant walls. Reduced curling has the further advantage of leaving a wider and more useful gap between the fabric 7 and the walls 11a,11b. This wider useful gap has a twofold benefit. On the one hand, it gives the flow of gaseous fluid a greater capacity to support and carry the fabric; and on the other, by coming between the fabric 7 and the walls 11a,11b, it prevents the fabric 7 from coming into contact therewith, thus limiting friction and allowing it to move forward with much less resistance.

[0030] In other words, therefore, the divergence of the duct 2all other conditions being equalallows the fabric 7 to be fed much more effectively and under much more favourable conditions of resistance which are particularly useful with coated fabrics or resin-impregnated fabrics with high surface adhesiveness.

[0031] From FIGS. 3 and 4, it may be noted that the apparatus 1 is perfectly reversible, which means that what has been said in relation to the stretch 15b of the duct 2 applies also to the other stretch 15a, obviously if the operation of the process tumbler, that is, if the direction of movement of the fabric 7 therein, is reversed.