Device for the introduction and/or the removal, in an airtight manner of solid bodies across one aperture at least of an enclosure treatment, more particularly under low pressure

A seal permitting wire, rod or the like to fed into a chamber at low prese comprising a Venturi tube constituting in its interior and in succession a convergence a neck and a divergence. The tube has a coaxial sleeve on its convergence side into which the solid to be treated can be introduced. This sleeve is partially engaged inside the Venturi tube over a length determined so as to create a rapid change of section which defines a dynamic joint zone in combination with the pressure, flow and speed of the fluid injected toward the inside of the Venturi tube.

BACKGROUND OF THE INVENTION 
The present invention has for its object a device for the introduction 
and/or the removal, in an airtight manner, of solid bodies across at least 
one aperature of an enclosure treatment, more particularly under low 
pressure. 
The object of the invention pertains more particularly fluid dynamics. 
Many up to date surface treatments are carried out within enclosures in 
which a more or less substantial vacuum is provided. There are such 
treatments which are carried out with a vacuum in the order of 1,333. 
Pascal, for instance the treatments in the vapour stage, or in the order 
of 1,333.10.sup.-1 Pascal, this is for instance the case of the deposits 
of titanium nitride through spraying. 
At the present time, the machines for vacuum treatment are discontinuous. 
In a general manner, they have a series of chambers in which different 
vacuum heads may prevail, said chambers being adapted for scouring, 
treating, drying, cooling, etc. in succession. Each successive step is 
characterized by the simultaneous opening of a plurality of valves which 
separate the enclosures two by two, and by the advancement of the whole of 
the treatment line, equal to the modular length of one enclosure. After 
each valve closing, the vacuum pump assemblies are actuated in order to 
restore the desired pressure. 
Such systems are not suitably adapted for treating products of substantial 
length or continuous, solid products, such as wires or sheet metals. When 
the solid body is travelling between two consecutive enclosures, as the 
pressure differences on either side of the wall are rather small, it is 
possible to do with a single aperture of communication, the discharge of 
the pumps compensating the leakage from an enclosure to the other one. 
However, the problem is different when the solid body is to be passed from 
the outside into the first enclosure, or from the last enclosure towards 
the outside. In this case, the well-known conventional systems are all of 
them burdened with defects, the more often latent ones. 
This is more particularly the case with the following treatment procedures: 
When as small clearance as possible is desired between the wire, or the 
sheet metal, and the outlet aperture, there is a scraping of the product 
against the wall. Although the resulting marks or scratching could 
sometimes be tolerated, prior to the treatment of the product, they occur 
again after the treatment, when the product is leaving the apparatus. 
When it is desired to cause a friction of the product, either a product of 
some length or a continuous product, within the interior of an elastic 
sphincter, there are then further drawbacks to be encountered as soon as 
the pressures are falling below some tens torrs, among which: degassing of 
the product, saturating vapour tension, exposure to heat or cold, 
pollution of the surface of the treated product, etc. 
When it is desired to have the product passed through a duct with a 
clearance of sufficient width to prevent the contact, and when various 
offset portions are provided, each one with suction means, it is then 
necessary to arrange a power rating in excess. Moreover, in the case of a 
continuous product, which is broken inadvertently, the automatic 
re-threading of said product without stopping the line is elaborate and 
rather uneasy. 
The obtention of a sealing, or at least of a sealing in part, by means of 
ferrofluids has also been suggested. However, there is here to be 
encountered either the saturating vapour tension of the liquid part of the 
ferrofluid, or the magnetism of the product; for instance, it is not 
possible to obtain a sealing with ferrofluids subjected to a magnetic 
field when the is on a basis of iron. 
In accordance with the invention, and to overcome these disadvantages, a 
device has been provided in a particularly simple and efficient manner, 
which permits the introduction and/or the removal, in a substantially 
airtight manner, of solid bodies across at least one aperture of a 
treatment enclosure the internal pressure of which is lower than the 
pressure in the immediate surroundings. 
SUMMARY 
For this purpose, the device is remarkable in that it is comprised of a 
venturi tube constituting internally and in succession a convergent, a 
neck and a divergent, said tube being connected, on the side of the 
convergent with a sleeve arranged and equipped to permit the injection of 
a fluid under pressure and the flow thereof toward the interior of the 
venturi tube; said sleeve, capable of being coupled to the enclosure, low 
pressure tank or the like, being provided internally, directly or in an 
inserted manner, with an axial sheath for introduction and communication 
between the aperture of said enclosure or the like and the venturi tube, 
said sheath co-operating with the convergent of the venturi tube 
practically up to the level of the neck, in order to form at this level a 
sudden change in section the effect of which is to define a dynamic 
sealing area in combination with the pressures of the fluid, the solid 
body or bodies being arranged to be introduced on the side of the 
divergent to be engaged without friction within the bore of the 
communication sheath in order to be introduced entirely and completely dry 
within the interior of the enclosure. 
These and further characteristics will be apparent from the following 
description.

DETAILED DESCRIPTION 
To make the object of the invention more concrete, this object will be 
described now in a non-limiting manner, with reference to the examples of 
embodiment illustrated in the Figures of the drawing. 
In accordance with the invention, and as shown more particularly in FIGS. 
1, 2 and 3, it has been contemplated to use the principle of the fluid 
horns for a novel application as immaterial seals. In the case of a 
laminar flowing, it is possible to achieve the following pattern: the 
fluid, starting from an initial pressure (P0), from a speed (V0), goes 
through a zero pressure or a practically zero pressure at the level of a 
sudden section widening to rise up again to atmospheric pressure at the 
outlet. For this purpose, the flowing is divided into three parts I, II 
and III respectively. 
In the first part I (FIG. 1), the pressure energy of said fluid is 
transformed into kinetic energy by a convergence (a) which serves for 
putting the fluid in motion. In the part II, which corresponds to a neck 
(b), a sudden change in section occurs; the fluid, initially in the 
section (So), at the speed (V0) and at the pressure (P0), is suddenly 
caused in a section (S1) to pass to a speed (V1) and to a pressure (P1) 
which is practically zero. A loss of energy through impacts is taken into 
consideration. 
In the third part III, the kinetic energy is transformed into a pressure 
potential energy by a divergence (c). From the section (S2) to the section 
(S3), at the outlet of the divergence (c), the fluid is caused to pass 
from the velocity (V2) to the velocity (V3) and from the pressure (P2) to 
the pressure (P3) corresponding approximately to the atmospheric pressure. 
It will be noted that the sudden change in section might occur either at 
the level of the connecting portion of the convergence (a) and of the neck 
(b) (FIG. 1), or ahead of the neck (b) (FIG. 2), or on a portion of the 
length of the neck (b) (FIG. 3). 
In a preferred manner, the sudden change in section is not originated 
within the divergence (c), as this would impair the efficiency. 
At the level of this sudden change in section, there is formed, in 
combination with the fluid flow, an area (2) corresponding to a dynamic 
sealing area. This physical process is particularly important and 
advantageous for promoting the travel of a solid body (a wire for 
instance) from any location at a pressure (P3) into, for instance, an 
enclosure the pressure (Po) of which is lower, and this with a steady and 
complete sealing between the two locations. 
Referring now to FIG. 4, there is shown here an example, which is not 
restrictive in any way, of embodiment of the device on the basis of the 
fundamental principles stated above. 
The device includes essentially a venturi tube (1) which constitutes 
internally and in succession the convergence (a), the neck (b) and the 
divergence (c). This Venturi tube (1) is integral, in a detachable manner 
or not, on the side of the convergence (a), with a coupling sleeve (2) 
configurated externally at (2a) to permit the injection of a fluid under 
pressure and the laminar flowing thereof toward the Venturi tube (1). 
The sleeve (2) is provided internally, directly or in an inserted manner, 
with an axial sheath (2b) for communication between the Venturi tube (1) 
and for instance an enclosure (3) to which the sleeve (2) may be 
connected. The sheath (2b) co-operates with the convergence (a) at the 
level of the neck (b), as stated before, in order to originate at this 
level the sudden change in section. The result of this is therefore the 
dynamic sealing area (Z). 
The external periphery of the sheath (2b), in combination with the inside 
wall (2c) of the sleeve, constitutes an annular space or chamber (2d) 
which communicates with the convergence (a) for the flow and the 
introduction of the fluid into the Venturi tube. 
In an important manner, which is not absolutely necessary, but which is 
strongly advisable, the external section (S) of the end of the sheath (2), 
at the level of the neck (b), as well as the section (S') of said neck (b) 
at right angles with the end of the sheath, must be suitably dimensioned 
in combination with the section (s) of the solid body to be introduced 
(FIG. 5). The effectiveness of the system (S and S') (i.e. without the 
solid body) must be the same as the effectiveness of the system ((S and 
(S'-s)) so that the ratio S/S and S/S'-s will be equivalent in order to 
lead to the same coefficient of pressure drop when the energy is 
transformed. Minimal performance will be set up thereby regardless of the 
conditions. 
As designed, the device is particularly well adapted for the inlet and/or 
the outlet in a completely sealed manner of solid bodies across an 
aperture (c) of a treatment enclosure (3) the pressure (Po) of which is 
lower than the pressure in the immediate surroundings (P3), which may be a 
further enclosure or the atmospheric pressure. 
The solid body or bodies, for instance wires, could be introduced on the 
side of the divergence (c), i.e. at the pressure level (P3), to be engaged 
without friction within the bore of the sheath (2) in order to be 
introduced through the aperture (o) into the enclosure (3) at the pressure 
(Po) to be subjected to various treatments in accordance with the desired 
specific applications. The dynamic sealing area which has been originated 
will prevent the enclosure (3) to be polluted either by the device or by 
the surroundings. 
Moreover, it will be observed, in a particularly important manner, that the 
solid body or bodies introduced into the device and/or the divergence (c) 
arrive into the processing tank entirely dry and dust free, considerable 
advantages being of course obtained thereby. 
Depending on the cases of application, the device (D) may for instance be 
mounted as indicated, on one side only of the enclosure (3) (FIG. 6), the 
solid bodies being introduced (manually, automatically) or by any 
appropriate means, on the same side of the divergence (C). 
Conversely, for a continuous processing of the solid bodies, the enclosure 
may be provided with two devices in accordance with the invention, and 
situated on the same axial alignment (FIG. 7), one of the devices 
corresponding to the inlet of the solid bodies, the other one 
corresponding to the outlet thereof. The sleeve (2), opposite to the 
divergence (c), is still located on the low pressure side (for instance 
enclosure). 
It is obvious that in accordance with the laws of dynamics of the fluid, 
the various parameters are calculated so that there will be no possible 
creeping of the fluid from the outside toward the interior of the 
enclosure. 
The injected fluid may be water, oil or the like. 
Likewise, the sleeve (2) may be provided internally with various 
arrangements, for instance to make adjustable in the linear position the 
communication sheath, to permit the solid bodies to be guided, etc. 
As such, the invention may be used in a particularly advantageous manner 
for the vacuum treatments, as well as for the chemical or electrochemical 
surface treatment of solid bodies having a substantial length, such as 
wires, section irons, sheet metals, etc. 
In the latter specific case of use concerning the chemical or 
electrochemical treatments, important advantages are offered by the device 
relative to the well-known procedures which are presently in use. 
Generally, and as shown quite schematically in FIG. 8, the wire (F) to be 
processed was to follow a special path to pass from a tank (A) to the 
other tank, in order to be subjected to the various necessary treatments 
(degreasing, pre-rinsing, rinsing, depassivation, galvanic deposit). 
With the device in accordance with the invention, it is possible, more 
particularly, to suppress this complex path of the wire and to enhance the 
processing in a relatively important manner, as in accordance with the 
prior art, and as an indication, it was possible to carry out the 
treatment quite approximately under 1A/dm2, whereas the application of the 
device, with a very intensive agitation, makes it possible to carry out 
the processus up to 5 to 10 A/dm2. 
Referring now to FIG. 9, there is shown here, as an example which is not 
restrictive in any way, an installation for the application of the device 
to a chemical or electrochemical treatment. 
The installation includes obviously a plurality of processing tanks, which 
are denoted generally at (B). 
At the inlet of the first tank (B1), there is mounted the device (D) 
connected on the sides of the convergent to a low pressure enclosure (E) 
the calibrated inlet aperture of which serves for load drops. Between each 
one of the following tanks are mounted in an opposite manner two venturi 
tubes (1)-sheath (2) assemblies, the convergences of each one of said 
assemblies being coupled by means of a low pressure common chamber (E1). 
It is pointed out that the low pressure chamber (E1) may be provided with 
an electrovalve shell and control means for the balance leakages of the 
vapour pressures. 
The last tank (B2), at the outlet thereof, and like the first tank (B1) at 
the inlet thereof, is provided with a Venturi tube (1)-sheath (2) 
assembly, the convergent of which is connected to a low pressure enclosure 
(E2). The convergences of each one of the Venturi (1)-sheath (2) 
assemblies are conveniently coupled to pumping means (P) related to each 
one of the corresponding tanks. 
The wire or other solid body to be processed may therefore be introduced, 
treated and removed from the first tank to the last one in an entirely 
linear manner, contrary to the well-known systems. 
The association and combination of several devices in accordance with the 
invention are also contemplated in order to make the system more effective 
still, thanks to the accumulation of the advantages of each one of the 
devices taken separately. 
This association may be effected either by combining n devices mounted in 
series, or with n groups of two devices mounted opposite. 
The advantages are clearly apparent from the description, and the following 
is to be more particularly pointed out: 
the simplicity of the device; 
the steady and complete sealing provided between the surroundings and the 
treatment enclosure; 
the products introduced into the device on the side of divergent arrive 
into the low pressure tank entirely dry, making it possible thereby to 
avoid the use of expensive and complex auxiliary means. 
The invention is not limited in any way to the use nor to the form of 
embodiment of the various parts thereof which have been more particularly 
described, and any alternative form of embodiment remains within the scope 
of the invention.