WO2001040562A1

WO2001040562A1 - Device for treating sheet material with water jets under pressure

Info

Publication number: WO2001040562A1
Application number: PCT/FR2000/003043
Authority: WO
Inventors: André Vuillaume; Laurent Schmit
Original assignee: Rieter Perfojet
Priority date: 1999-12-01
Filing date: 2000-10-31
Publication date: 2001-06-07
Also published as: FR2801909A1; AU1285401A; FR2801909B1

Abstract

The invention concerns a injector for treating a sheet material with jets/needles of water comprising: a body (1) supplying water under pressure including a supply chamber (2) extending over the whole length of said body, and wherein is brought through a filter (4), water under pressure; a distributing zone, dispensing water under pressure over the whole treated width against a microperforated plate (7) whereof the holes defining needles of water (8) directed against the surface of the material to be treated; clamping jaws (9) for maintaining the microperforated plate (7), and forming between them a longitudinal slot allowing through water jets. The invention is characterised in that it comprises an air-circulating chamber (17) opposite the lower surface (11) of the clamp (9), the wall of said chamber consisting of a plate (14) made from a porous material.

Description

DEVICE FOR TREATING SHEET MATERIALS USING PRESSURIZED WATER HEADS.

Technical Field The present invention relates to an improvement brought to the installations making it possible to treat sheet materials by means of jets of water under pressure, which act on the structure in the manner of needles, used in particular to treat nonwoven structures in in order to give them cohesion and / or modify their appearance.

One such technique, which has been proposed for decades, as is apparent in particular from US Patents 3,214,819 and 3,485,706, consists in subjecting the sheet structure to the action of water jets coming from one or more successive ramps, the tablecloth being supported by a porous or perforated rotating conveyor or cylinder, subjected to a suction source allowing the recovery of water.

One of the essential elements of such installations is the system for forming jets or needles of water, commonly designated by the expression "injector".

The invention relates more particularly to a new type of injector.

Previous techniques

The injectors used today and which, concretely, can be produced in accordance with the teachings of FIG. 42 of US Pat. No. 3,485,706 and corresponding passages of the description of this document, as well as much more detailed concrete embodiments emerging in particular from US Pat. No. 3,613,999 and EP 400,249 (corresponding to US 5,054,349), the latter document describing a type of injector which not only allows a supply of water under very high pressure (greater than 100 bars) has a structure such that it allows the perforated plate to be put in place and removed through which micro-jets are easily made.

FIG. 1 attached illustrates in general, in perspective, the structure of an injector produced in accordance with document EP-A-0 400 249. If we refer to this figure, the injector is therefore in the form of a ramp, continuous, extending transversely to the direction of travel of the sheet material (F) to be treated, nonwoven for example, and the length of which is adapted to the width of said material. This ramp may consist of a single elementary module or a plurality of modules juxtaposed with each other.

Such a ramp consists of a main body (1), making it possible to resist any deformation under water pressure, at the upper part of which is formed a chamber (2), generally of cylindrical shape, supplied with water under pressure through a pipe (3) supplied by a pump (not shown).

Inside the chamber (2), a cartridge (4) is arranged, constituted for example by a perforated cylinder lined with a filter cloth, which not only acts as a filter, but also serves as a distributor.

The pressurized water introduced inside the chamber (2) then flows through cylindrical bores (5), spaced with a regular pitch over the entire width of the injector, a hole whose diameter is generally between 4 mm and

10 mm, the thickness of the wall between two consecutive holes being of the order of 3 to

5 mm.

These cylindrical holes (5), the outlet end of which may optionally be in the form of a shell, then open into a lower chamber (6) at the base of which is positioned a plate (7) provided with micro-perforations, the diameter of which may be between 50 and 500 μm and preferably between 100 and 200 μm, making it possible to form water jets or needles (8) which act directly against the surface of the material (F), nonwoven web for example, treat.

Maintaining the perforated plate (7) against the main body of the injector, is obtained for example in accordance with the teachings of EP 400249 by means of longitudinal jaws (9) subjected to the action of hydraulic cylinders which allow to exert a clamping action by means of a set of spreaders and tie rods arranged along the injector. A seal (not shown) is disposed between the perforated plate (7) and the base of the main body (1).

Such a system for distributing water under pressure against the micro-perforated plate intended to form the needles of water, and which therefore uses holes (5) which open into a lower chamber (6), makes it possible to distribute water correctly over the entire length of the injector, the same water flow passing through each port.

Taking into account in particular the increasingly high production speeds which cause significant water flow rates, this leads to a phenomenon of formation of water droplets (10) which condense on the underside (11) of the jaws (9 ) from the injector, droplets (10) which are entrained by the jets (8) leading to the production of defects in the product.

Such a phenomenon is particularly important in the case of jaws whose lower face (11) is flat, as illustrated in FIG. 2.

In fact, in such a case, the droplets (10) which therefore form on the underside (11) of the jaw, and which result both from the rebound (R) of the jets (8) on the cylinder (C) (or carpet ) carrying the material to be treated as condensation of the ambient fog, are entrained, at a high speed, in the direction of the jets (8) under the effect of the air currents, shown diagrammatically by the arrow (12), created in this zoned.

The drops (10) tend to get larger as they advance on the underside (11) of the jaw. They detach from the latter as soon as they come as close as possible to the jets (8).

They are then projected against the jets (8), which has the effect of temporarily destroying them, but however causes defects on the treated product and more particularly on light products.

To alleviate this problem, it has been proposed, as is apparent from FIG. 3, to extend the outlet orifice of the jets outside the jaw (9) by a spout (13) which forms a barrier at the end of the lower face (11) of said jaw, a barrier which prevents the entrainment of the droplets at the level of the jets.

Such a solution is however not satisfactory, because the drops (10) still tend to be sucked by the water jets (8).

To more effectively solve this problem, it was then proposed, as shown in FIG. 4, to form a suction box (16) on the underside of the jaw, box subjected to a depression of the order from 50 to 100 millibars, produced in a smooth metal sheet. This box has a slot (15) located slightly behind the jets exit area (8).

In such a case, the droplets therefore form against the external surface of the box. It has been observed that said droplets collect in the form of trickles of water which are very difficult to aspirate.

Statement of the invention

Now we have found, and this is what is the subject of the present invention, an improvement made to this latter type of jaw as illustrated in FIG. 4, which makes it possible to practically perfectly solve the problem of the formation phenomenon. of drops of water at the level of the jaws and completely eliminates the recovery of said drops by the treatment jets, and consequently, the defects that this may cause in the production of the material.

In general, the injector according to the invention therefore allowing the treatment of a sheet material (nonwoven, textile complex, film, paper ...) by means of jets / needles of water consists :

_ a pressurized water supply body comprising a supply chamber extending over the entire length of said body, and inside which water under pressure is brought through a filter ;

_ a distribution zone, distributing the water under pressure over the entire treatment width against a plate provided with micro-perforations, the holes of which define water needles directed against the surface of the material to be treated;

_ clamping jaws ensuring the maintenance of the micro-perforated plate and which form between them a longitudinal slot allowing the passage of the jets. The injector according to the invention is characterized in that it comprises an air circulation chamber, arranged below the underside of the jaws, the wall of said chamber consisting of a continuous plate made of a porous material .

As a porous material used in the production of the lower wall of the chamber, a plate based on a sintered metal is preferably used, of the type described in patent US-A-3,359,622 or the patent FR-A -2,642,984, materials which, to date, are more particularly used in the field of filtration.

Within the meaning of the present invention, the permeability of the porous material constituting the plate is such that the pressure drop created varies from 1 to 5 millibars per millimeter of wall thickness under an air flow rate of 100 liters per hour per square centimeter .

Such a sintered metal, stainless steel or bronze plate can have a thickness of the order of 2 to 3 mm, and, surprisingly, it has been found that it makes it possible to considerably limit the formation of drops at the level of its surface.

This can be explained by the fact that this very rough surface "breaks", said drops (10) when they move.

In a jaw comprising a spout, this plate of porous material is spaced by a distance d_de the end of the spout, a distance generally between 2 and 5 mm.

As said previously, in the chamber formed between this plate and the underside of the jaw, an air circulation is created which can either be a suction or a blowing carried out not only through the space between the end of the beak and the edge of said plate, but also through the thickness of the latter. Brief description of the drawings

The invention and the advantages which it brings will however be better understood thanks to the embodiments given below by way of indication, but not limitation, and which are illustrated by the appended diagrams in which: _ as indicated previously, FIG. 1 illustrates, schematically, a sectional view along its vertical plane of symmetry, the structure of an injector according to the prior art;

_ Figure 2 illustrates, in turn, schematically, the turbulence and the formation of water droplets at the clamping jaws, Figures 3 and 4 illustrating the solutions proposed to date to solve the problems posed by a such training;

_ Figures 5 and 6 illustrate, for their part, the embodiment of an injector according to the invention, the jaws are equipped with means for eliminating the formation of water droplets on its underside and comprising a chamber air circulation can be either a suction (Figure 5) or a blowing (Figure 6).

Manner of Carrying Out the Invention

Referring to FIGS. 5 and 6 appended, and using the same references for the common elements as those used to describe the state of the art illustrated by FIGS. 1 and 3, the injector according to the invention is made up, similarly to this state of the art, a main body (1) made of steel, having a length of 3500 mm, a total width of 200 mm, and a height of 200 mm.

At the base of the main body (1), is fixed a perforated micro-plate (7), fixing obtained by means of lateral jaws (9).

The micro-perforated plate (7) can be produced from a steel strip 1 mm thick, 25 mm wide and comprising at least one row of orifices, the diameter of which is preferably between 100 and 200 μm and which are spaced apart by a distance generally between 0.6 and 1.2 mm.

Seals are of course provided between the base of the upper body and the surface of the micro-perforated plate. Conventionally, the water jets (8) produced are directed against the surface of a cylinder (C) (or mat) supporting the material to be treated, and flow below the plate (7) at the inside a continuous slot formed by the two opposite faces of the jaws (9) fitted at their base with a spout (13)).

According to the invention, an air circulation chamber (17) is formed opposite the underside (11) of the jaw (9), the wall of this chamber being constituted by a plate (14) made of a material. porous, preferably sintered metal.

This plate (14) is spaced at a distance of approximately 5 to 10 mm from the underside (11) of the jaw, and is also spaced at a distance d, of the order of 2 to 3 mm, relative to the rear of the spout (13).

This porous plate made of rough sintered metal can be produced, for example, from a material sold under the name "Poral" by the company Sintertech and which, to date, is used essentially in the field of filtration.

In the two illustrated embodiments, this plate (14) of sintered material has a width of 6 cm and extends over the entire length of the injector.

It can be mounted either at the outlet of a suction assembly (16) (Figure 5) or at the outlet of an air blowing assembly, also referenced (16) (Figure 6).

When a suction is carried out, the vacuum produced is of the order of 200 to 300 mm from a column of water.

In the case of a blowing as illustrated in FIG. 5, the air pressure is advantageously between 200 and 300 millibars.

In the case of suction, the water or vapor which condenses on the plate (14) flows not only through the slot (15) between the end of the plate (14) and the rear part of the spout (13), but also through said plate (14).

In the case of a blowing, the air current tends to push the condensed water out of the area of action of the jets (8).

Thanks to such a design, it has been found that the total elimination of micro-drops of water was caused at the base of the injector, with the consequence of improving the quality of the articles produced.

Of course, the invention is not limited to the concrete example given above, but it covers all the variants produced in the same spirit.

Thus, the plate intended to form the air circulation chamber could be based on another porous material than a sintered metal, and be constituted for example by a micro-perforated sheet, or even a metallic fabric.

Claims

1 / Injector for treating a sheet material by means of water jets / needles comprising: _ a body (1) for supplying pressurized water comprising a supply chamber (2) extending over the whole the length of said body, and inside which water, under pressure, is brought through a filter (4);

_ a distribution zone, distributing the water under pressure over the entire treatment width against a plate (7) provided with micro-perforations, the holes of which define water needles (8) directed against the surface of the material to be treat;

_ clamping jaws (9) ensuring the maintenance of the micro-perforated plate

(7) and which form between them a longitudinal slot allowing the passage of the jets; characterized in that it comprises a chamber (17) for air circulation opposite the underside (11) of the jaw (9), the wall of this chamber being constituted by a plate (14) made of a porous material .

2 / Injector according to claim 1, characterized in that the plate of porous material (14) is made of sintered metal.

3 / injector according to one of claims 1 and 2, characterized in that the end of the plate of porous material (14) delimiting the chamber (17) of air circulation is spaced from the spout (13) of the clamping jaw so as to define a slot (15) for the passage of air.

4 / Injector according to claim 3, characterized in that the width of the slot (15) is between 2 and 5 mm.

5 / Injector according to one of claims 1 to 4, characterized in that the plate (14) of porous material is based on a sintered metal in stainless steel or bronze, said plate having a thickness of the order of 2 at 3 mm.