Installations for the treatment of strip material in a gaseous medium

The invention relates to installations for the treatment in a gaseous medium of a strip material passing over rollers (6). Each roller (6) is driven in rotation by an endless belt (10) serving also for the embarkment of the strip, this endless belt passing over drive pulleys (15) which drive the corresponding roller (6) by coupling means (101) ensuring a "free wheel" function and a "coupler" function. The installation is useful for the heat treatment, especially the drying of a strip material.

The invention relates to installations for the treatment in a gaseous 
medium, notably for heat treatment, of a strip material. 
Such an installation comprises a plurality of treatment zones in which the 
strip material is supported by the aerodynamic effect of several gas 
discharges coming from holes in opposite walls of caissons arranged on 
each side of the treatment zone. 
These treatment zones are generally arranged parallel to one another and in 
a horizontal arrangement thus forming treatment zone stages. 
In any case, return rollers are provided to support the strip material 
during its travel between the treatment zones; the strip hence passes from 
the exit of one treatment zone to the entrance of the following treatment 
zone, these passages being effected in the form of a half-turn around a 
return roller if the treatment zones are arranged in stages. 
When the installation is in operation, the strip material is extracted from 
the installation by an extractor mechanism generally constituted by two 
pressure rollers between which the strip material passes, at least one of 
these pressure rollers being driven in rotation by drive means. 
When putting the installation into operation, it is necessary, 
on the one hand to guide and route the strip material from its entry into 
the first treatment zone up to its exit from the last treatment zone where 
said strip is then taken over by the extractor mechanism, 
and on the other hand, to drive in rotation the return rollers in order 
that this driving should not be through the strip material in the course 
of its introduction into the installation. 
The guidance and routing of the strip material on starting up the operation 
of the installation is effected through at least one endless belt set in 
motion by drive means and drawing the strip by means of a gripping device 
fixed to this endless belt to catch (before the first treatment zone) and 
release (after the last treatment zone) the end of the strip. 
The driving in rotation of the return rollers on the setting in operation 
of the installation is effected through as many driving pulleys, of the 
same initial diameter as the return rollers and over which the endless 
belt passes, as there are return rollers to be driven, coupling means 
being interposed between each drive pulley and the corresponding return 
roller. 
It is known that in such installations, problems are encountered in the 
realization of these coupling means. 
In fact, during the period of setting the installation in operation, 
problems of two types are met: 
on the one hand, the strip material may undergo a longitudinal shrinkage 
during its travel through the installation, notably where heat treatment 
is concerned; failing special precautions, the strip runs the risk of 
being torn more particularly when it passes over the return rollers, 
and, on the other hand, the endless belt must, at the moment of starting it 
up, drive all of the return rollers; failing special precautions, one is 
then led to provide oversized drive means to ensure the starting up of the 
endless belt, as well as a cross-section of this endless belt which 
withstands the traction imposed on it by the opposing torque at the moment 
of starting up. 
It is an object of the present invention to overcome the drawbacks 
resulting from these two problems. 
It is an object of the invention to provide an installation in which the 
design of the coupling means enables, 
on the one hand, any risk of tearing of the strip material when there is 
longitudinal shrinkage to be avoided, 
and on the other hand, recourse to endless belt entraining drive means 
which are much smaller and capable of reducing to a very considerable 
extent the traction forces undergone by the endless belt, and hence its 
cross-section. 
According to the invention, these coupling means, interposed between each 
drive pulley and the corresponding return roller, are arranged to ensure 
"free wheel" operation (so that each roller can rotate faster than the 
corresponding drive pulley) and a "coupling function" (so that each roller 
is driven progressively by the corresponding drive pulley). 
Preferably, the "coupling" function is ensured adjustably, so that the time 
of setting up the speed of each return roller is adapted to the location 
of the return roller concerned in the installation, that is to say adapted 
to the time interval which separates the moment when the gripping device 
has fastened the end of the strip material to the moment when the gripping 
device passes over the roller concerned. 
In a first embodiment, the coupling means are constituted by the 
association of a free wheel device and a coupler device. 
This free wheel device and this coupler device may be arranged so that, 
between the drive pulley and the return roller concerned, 
either, the free wheel and then the coupler device are successively 
encountered, 
or, the coupler device and then the free wheel device are successively 
encountered. 
In another embodiment, the coupling means are constituted by a single 
mechanical assembly enclosing a free wheel and a coupler of which certain 
parts may be combined. 
This mechanical assembly can be arranged so that the transmission between 
the drive pulley and the corresponding return roller is effected, 
either, by first encountering the free wheel and then the coupler, 
or, by first encountering the coupler and then the free wheel. 
The invention consists, apart from the features which have just been 
considered, of certain other features which are utilized preferably at the 
same time and which will be more explicitly considered below.

The installation, as shown in FIGS. 1 and 2, is an installation for the 
heat treatment (notably the drying) of a strip material. 
This installation includes a plurality of treatment zones 1, parallel to 
one another and in which the strip material 2 is supported by the 
aerodynamic effect of several discharges of hot gas emerging from holes 3 
formed in the opposed walls 4 of caissons 5 arranged on both sides of each 
of said treatment zones 1. 
These treatment zones 1 are generally arranged horizontally and thus form 
treatment zone stages. 
In any case, the return rollers 6 are provided to support the strip 
material 2 during its routing between the treatment zones 1; the strip 2 
hence passes from the exit of one treatment zone 1 to the entrance of the 
following treatment zone 1, these passages being effected in the form of a 
half-turn around a return roller 6 if the said treatment zones are 
arranged in stages. 
When the installation is in operation, the strip material is extracted from 
the installation by an extractor mechanism generally constituted by two 
presser rollers 7 and 8 between which the abovesaid strip 2 passes, one at 
least of these presser rollers, for example the presser roller 7, being 
driven in rotation by drive means 9. 
For placing the installation in operation, it is necessary, 
on the one hand, to guide and route the strip material 2 from its entrance 
E into the first treatment zone 1 up to the exit S from the last treatment 
zone 1 where said strip 2 is then taken over by the extractor mechanism 7, 
8 driven by the drive means 9, 
and on the other hand, to drive in rotation the return rollers 6 in order 
that this driving should not be done through the strip material 2 in the 
course of introduction into the installation. 
The guiding and routing of the strip material 2 on the placing of operation 
of the installation is effected through an endless belt 10, set in motion 
by drive means 13 synchronized with drive means 9, so that after its 
setting up at speed the endless belt 10 has the same peripheral speed as 
the presser roller 7 of the extractor mechanism. These drive means 13 draw 
the strip 2 by means of a gripping device 12 fixed to this endless belt 10 
to engage (before the first treatment zone 1) and disengage (after the 
last treatment zone 1) the end of the strip 2. 
The driving in rotation of the return rollers 6 on the placing of the 
installation in operation is effected through as many drive pulleys 15 
over which the endless belt 10 passes as there are return rollers 6 to be 
driven, coupling means 101 being interposed between each drive pulley 15 
and the corresponding return rollers 6; of course, these drive pulleys 15 
have the same initial diameter as the return rollers 6 (FIGS. 3 and 4). 
These coupling means 101, interposed between each drive pulley 15 and the 
corresponding return roller 6, are arranged to ensure a double function, 
namely, 
a "free wheel" function giving the possibility to each return roller 6 of 
being able to rotate faster than the corresponding drive pulley 15, which 
permits the peripheral speed of each return roller 6 to be equal to the 
passing speed of the endless belt 10, whilst permitting this peripheral 
speed of each return roller 6 to become greater than the passing speed of 
the endless belt 10 under the effect of longitudinal shrinkage of the 
strip 2, 
and a "coupler" function giving the possibility to each return roller 6 of 
being able to be driven progressively by the corresponding drive pulley 
15, which permits the size of the drive means 13 placing the endless belt 
10 in motion to be reduced and the cross-section of the endless belt 10 to 
be reduced since the traction imposed on it by the opposing torque at the 
moment of starting up is found to be considerably reduced by the slippage 
permitted by this "coupler" function. 
Preferably, the "coupler" function is ensured adjustably, so that the time 
of setting up the speed of each return roller 6 is adapted to the position 
of the return roller 6 concerned in the installation. 
In other words, the "coupler" function may be adapted to the time interval 
which separates the moment when the gripping device 12 has engaged the end 
of the strip 2 from the moment when the gripping device 12 passes over the 
roller concerned. 
In practice, this result is achieved by a relatively limited number of 
different adjustments. 
For example, the adjustment of the "coupler" function of the coupling means 
101 of the first return roller 6 (marked a) may be such that the 
establishment of the speed of said return roller is ensured in about two 
seconds, if it needs more than two seconds for the gripping device 12 to 
reach this roller 6a from its starting position. 
For the second return roller 6 (marked b), the adjustment of the "coupler" 
function of the coupling means 101 of said return roller could then be 
such that the establishment of the speed of this return roller is ensured 
in about 20 seconds if it needs more than 20 seconds for the gripping 
device 12 to reach this roller 6b from its starting position. 
For the other return rollers 6 (marked c, d, etc.) one may continue to 
increase the time of establishing the speed of the latter by adjustment of 
the "coupler" function of their coupling means 101 insofar as this time is 
still less than the time taken by the gripping device 12 to reach said 
rollers. 
Although it is possible, as indicated previously, to constitute the 
coupling means 101 by the association of a free wheel device and a coupler 
device, it seems that there is reason to give preference to the embodiment 
illustrated in FIGS. 3 and 4 which relate, the one, (FIG. 3), to an 
installation with lateral introduction, and, the other (FIG. 4), to an 
installation with central introduction. 
According to this embodiment, these coupling means 101 are constituted by a 
single mechanical assembly 102 enclosing a free wheel 103 and a coupler 
104. 
Generally, the coupling means 101 may be arranged so that the transmission 
between the drive pulley 15 and the corresponding return roller 6 is 
effected, 
either, by encountering first the free wheel 103 (or the free wheel 
device), and then the coupler 104 (or the coupler device), 
or, by encountering first the coupler 104 (or the coupler device, and then 
the free wheel 103 (or the free wheel device). 
The mechanical assembly 102 may advantageously be constructed so that 
certain parts of the free wheel 103 are combined with certain parts of the 
coupler 104. On this subject, it is possible to resort to the embodiment 
illustrated in FIGS. 3 and 4 and according to which reliance is placed on 
a free wheel 103 with a roll or with a roller and with a friction coupler 
104. 
The mechanical assembly 102 is then constructed so that the transmission is 
effected first through the coupler 104 and then through the free wheel 
103. 
The coupler 104 includes a driving plate 105, friction linings 106 and a 
driven plate 107. 
The free wheel 103 may then include rolls or rollers 108 inserted between a 
driven plate 109 and a driving plate which may be constituted by the 
driven plate 107 of the coupler 104. 
It would also be possible to resort to a mechanical assembly 102 
constituted by a free wheel clutch device such as that described in French 
Pat. No. 1,285,989 and its First Certificate of Addition No. 81,683, filed 
respectively on Jan. 17, 1961 and May 21, 1962, by Madame NICOT, nee 
Georgette VOILLOT, for "Free wheel clutch". 
As regards the installation as a whole, it may be indicated that it is 
particularly advantageous to resort to single drive means replacing the 
drive means 9 of the extractor mechanism and the drive means 13 of the 
endless belt 10. 
The single drive means (not shown) would then include a clutch device 
enabling the driving of the endless belt 10 from its placing in operation 
by the introduction of the strip material, whilst they would drive the 
extractor mechanism constantly, the assembly then being designed so that 
after its setting up in speed through the clutch the endless belt 10 has 
the same peripheral speed as the presser roller 7 of the extractor 
mechanism. 
As for the rest of the installation, it may advantageously be constructed 
as indicated in French Pat. No. 1,598,722, filed Dec. 24, 1968 by the 
TUNZINI AMELIORAIR Company for "Improvements in or to installations for 
the treatment in a gaseous medium of strip materials" and assigned to 
Applicant. 
Accordingly and whatever the embodiment adopted, there is provided an 
installation which has a certain number of advantages which are summarized 
below: 
the assembly of the coupling means ensuring the "free wheel" function and 
the "coupler" function enables the transmission of an adjustable constant 
torque to the return rollers; 
on the starting-up of the endless belt, this adjustable constant torque 
enables the progressive placing in rotation of the assembly of return 
rollers until synchronization is reached between the passage speed of the 
endless belt and the peripheral speed of each return roller, this 
synchronization being reached in a time which depends on the adjustment of 
the "coupler" function and of the inertia of the return roller driven; 
moreover, after the synchronization between the return roller and the 
endless belt is reached, each return roller may, due to its "free wheel" 
function, be driven freely at an over-speed with respect to the endless 
belt as soon as the return roller is pulled at its periphery by tension of 
the strip material caused by shrinkage; 
lastly, each return roller may be driven freely by the strip material, once 
the introduction of this strip material is effected, that is to say, once 
that the endless belt, and hence the included drive pulleys, is stopped. 
This group of advantages enables, with respect to known devices, the 
realization of the introduction of the material with single drive means of 
much lower power. 
It enables also a considerable reduction in the size and the strength 
required in the endless introduction belt, due to the considerable 
reduction in the forces imposed on the latter during the operation of 
introduction. 
Consequently, it enables the speeds of introduction and the width of the 
latter to be considerably increased. 
As is self-evident, and as emerges already from the foregoing, the 
invention is in no way limited to those of its methods of application and 
embodiments which have been more particularly envisaged; it encompasses, 
on the contrary, all modifications.