Device for cooling a foil tubing

A device for cooling foil tubing as it issues from an annular nozzle surrounded by an annular air outlet orifice. A first cylindrical chamber is connected in the direction of the course of the foil tubing to the air outlet orifice, and has an iris diaphragm at its upper end. The air flowing into the chamber flows out between the inner rim of the diaphragm and the foil tubing. At least one first additional chamber is connected to the first chamber at the other side of the iris diaphragm. The additional chamber has a first additional iris diaphragm at its upper end which has an adjusting mechanism independent of the iris diaphragm at its upper end of the first chamber. The walls of both chambers are constructed of solid material.

INTRODUCTION 
This invention concerns a device for cooling foil tubing issuing from an 
annular nozzle in which the nozzle is surrounded by an annular air outlet 
orifice, to which a cylindrical chamber is connected in the direction of 
the course of the foil tubing which, on the one hand, is connected with 
the air outlet orifice, and on the other hand, has an iris diaphragm, the 
air flowing into the chamber flowing off between the inner rim of the 
diaphragm and the foil tubing. 
A BRIEF DESCRIPTION OF THE PRIOR ART 
In a known device of this type, the air outlet orifice opens directly into 
the chamber, which has an elastic wall. The cooling air issuing from the 
air outlet orifice flows along the tubing and issues at the iris 
diaphragm. The air current produces negative pressure inside the chamber. 
This negative pressure together with the air current outside the foil 
tubing causes this tubing to expand after leaving the nozzle while 
diffusing the chamber. 
SUMMARY OF THE INVENTION 
It is an object of this invention to construct the device in such a way 
that the diameter of the tubing can be maintained as constant as possible 
while diffusing the cooling device. 
In summary, the invention is a device for cooling foil tubing as its issues 
from an annular nozzle in which the nozzle is surrounded by an annular air 
outlet orifice. A first cylindrical chamber is connected in the direction 
of the course of the foil tubing to the air outlet orifice, and has an 
iris diaphragm. The air flowing into the chamber flows out between the 
inner rim of the diaphragm and the foil tubing. At least one first 
additional chamber is connected to the first chamber at the other side of 
the iris diaphragm. The additional chamber has a first additional iris 
diaphragm which has an adjusting mechanism independent of the one iris 
diaphragm. The walls of both chambers are constructed of solid material.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The tubing, which is in the plastic state, issues from the nozzle 1. It is 
cooled on its outer surface by cooling air which flows from the annular 
air outlet orifice 2' into the chamber 2. An iris diaphram 4 is mounted on 
a flange 3, which is connected to the chamber 2 and surrounds it. The 
laminae 5 of this iris diaphragm 4 can be adjusted by means of an 
adjusting collar 6, arranged with a handle 7, so that the opening of the 
iris diaphragm 4 can be manually adjusted. The iris diaphragm 4 is located 
between the flange 3 and an additional flange 8, whereby sealing rings are 
provided between the flanges 3, 8 and the iris diaphragm 4. 
Flange 8 forms the lower closure of a first chamber 9, whose wall 10 is 
comprised of hard material, preferably acryl glass. A ring flange 11, 
which is connected with the ring flange 8 by means of spacer pins 12, is 
mounted onto this cylindrical wall 10. A further iris diaphragm 4', whose 
construction is identical with the construction of the iris diaphragm 4, 
is mounted onto flange 11. The diameter of the lamellar opening can be 
adjusted by means of a handle 7'. The iris diaphragm 4' is arranged 
between the ring flange 11 and a ring flange 16 which is identical to it, 
which are connected to one another by means of spacer pins 13. Sealing 
rings are, in turn, provided between the ring flanges 11, 16 and the iris 
diaphragm 4'. 
Flange 16 forms the lower closure of a second chamber 14, whose cylindrical 
wall 15 also is comprised of acryl glass. A ring flange 11', which is 
connected with the ring flange 16 by means of spacer pins 12', is mounted 
onto this cylindrical wall 15. Flange 11' is identical to the ring flanges 
11, 16. A third iris diaphragm 4" is placed between this flange 11' and an 
additional ring flange 16' which is identical to it. Sealing rings are, in 
turn, provided between this iris diaphragm 4" and the flanges 11', 16'. 
The diaphragm aperture of the iris diaphragm 4" is adjustable by means of 
a handle 7". The two ring flanges 11', 16' are, in turn, connected to one 
another by means of spacer pins corresponding to the spacer pins 13. 
The cylindrical wall 17 of a third chamber 18 is mounted on the ring flange 
16', the wall 17 of which, in turn, is comprised of acryl glass. A ring 
flange 11", which is connected with flange 16' by means of spacer pins 
12", is mounted on the wall 17. This flange 11", which is identical to the 
flanges 11, 16, has a fourth iris diaphragm 4"'. The diaphragm aperture of 
the latter iris diaphragm can be manually adjusted by means of a handle 
7"'. 
The inside of the tubing issuing from the nozzle 1 is, moreover, cooled by 
an internal cooling device of known construction which is not shown. 
By regulating the amount of air issuing from the air outlet orifice 2 and 
by adjusting the diaphragm openings of the iris diaphragms 4, 4', 4" and 
4"', it is possible to keep the diameter of the tubing passing through the 
device constant to a great extent. The flow of the tubing and thus its 
diameter can be observed by means of the transparent walls 10, 15, 17 of 
the chambers 9, 14, 18. 
As can be seen in the drawing, the chambers 9, 14 and 18 of this embodiment 
of the invention have the same diameter and the same height. Dependent on 
the respective operating parameters, however, it can, in some cases, be 
more advantageous to construct chamber 9 or chambers 9 and 14, at a 
constant diameter, with a smaller height, for example, half the height as 
compared to the remaining chambers. Other additional, similarly 
constructed chambers can be arranged beyond chamber 18. 
For example, in an embodiment the volumes of the additional chambers can be 
about equal. In another embodiment the values of the first additional 
chamber can be approximately half as large as the volume of the other 
additional chambers. In a further embodiment the volume of the third 
additional chamber can be about twice as great as the volume of the other 
additional chamber.