U.S. patent application number 12/069887 was filed with the patent office on 2008-08-28 for method and device for connecting plastic tubes end to end.
This patent application is currently assigned to TECHNORD FRANCE SAS. Invention is credited to Michel Foucart, Philippe Lecourt, Jean Ringot, Benjamin Wassmer, Jaouad Zemmouri.
Application Number | 20080202669 12/069887 |
Document ID | / |
Family ID | 38480635 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080202669 |
Kind Code |
A1 |
Zemmouri; Jaouad ; et
al. |
August 28, 2008 |
Method and device for connecting plastic tubes end to end
Abstract
In order to connect two plastic tubes end to end, the
extremities of which are closed by compression and welding or
gluing of the tube wall, the two closed extremities of the tubes
are axially aligned and placed in abutment, the two closed and
abutting extremities of the tubes are heated from a distance and
without contact and the two extremities of the tubes are axially
brought together, so as to splay and weld together the extremities
of the tubes end to end, while constantly maintaining said
extremities in abutment.
Inventors: |
Zemmouri; Jaouad; (Genech,
FR) ; Ringot; Jean; (Mons En Baroeul, FR) ;
Wassmer; Benjamin; (Wattiginies, FR) ; Lecourt;
Philippe; (Rebecq, BE) ; Foucart; Michel;
(Rumillies, BE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
TECHNORD FRANCE SAS
Villeneuve d'Ascq
FR
OPTICAL SYSTEM & RESEARCH FOR INDUSTRY AND SCIENCE OSYRIS
SA
HELLEMMES
FR
|
Family ID: |
38480635 |
Appl. No.: |
12/069887 |
Filed: |
February 12, 2008 |
Current U.S.
Class: |
156/158 ;
156/391 |
Current CPC
Class: |
B29C 65/7802 20130101;
B29C 66/5221 20130101; B29C 66/93441 20130101; B29C 57/10 20130101;
B29C 66/4312 20130101; B29C 65/1425 20130101; B29C 65/1654
20130101; B29C 66/91941 20130101; B29C 65/1629 20130101; B29C
66/91221 20130101; B29C 65/1635 20130101; B29C 65/76 20130101; B29C
65/02 20130101; B29C 66/001 20130101; B29C 66/9141 20130101; B29C
66/71 20130101; B29K 2027/06 20130101; B29L 2023/007 20130101; B29C
66/83221 20130101; B29C 66/8242 20130101; B29C 66/91645 20130101;
B29C 66/857 20130101; B29C 66/0242 20130101; B29C 66/8161 20130101;
B29C 66/8223 20130101; B29C 66/919 20130101; B29C 65/168 20130101;
B29C 2035/0822 20130101; B29C 65/103 20130101; B29K 2101/12
20130101; A61M 39/146 20130101; B29C 66/961 20130101; B29C 66/91445
20130101; B29K 2995/0067 20130101; B29C 65/1412 20130101; B29C
66/522 20130101; B29C 66/91216 20130101; B29C 66/43 20130101; B29C
66/1142 20130101; B29L 2031/7148 20130101; B29C 66/73117 20130101;
B29C 66/73921 20130101; B29C 65/04 20130101; B29C 66/1122 20130101;
B29C 66/939 20130101; B29C 65/72 20130101; B29C 66/91411 20130101;
B29C 66/71 20130101; B29K 2027/06 20130101 |
Class at
Publication: |
156/158 ;
156/391 |
International
Class: |
B65H 69/00 20060101
B65H069/00; B65H 69/08 20060101 B65H069/08; B65H 69/02 20060101
B65H069/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 2007 |
FR |
07/01014 |
Claims
1. A method for connecting two plastic tubes end to end, the
extremities of which are closed by compression and welding or
gluing of the tube wall, wherein the two closed extremities of the
tubes are axially aligned and placed in abutment, the two closed
and abutting extremities of the tubes are heated from a distance
and without contact and the two extremities of the tubes are
axially brought together, so as to splay and weld together the
extremities of the tubes end to end, while constantly maintaining
said extremities in abutment.
2. The method of claim 1, wherein order to heat at a distance and
without contact the two closed and abutting extremities of the
tubes, a laser beam is used.
3. The method of claim 2, wherein the laser beam simultaneously
comes into contact with the two closed and abutting extremities of
the tubes.
4. The method of claim 3, wherein the laser beam is orientated
transversally to the compression plane of the two extremities.
5. The method of claim 4, wherein the laser beam scans the closed
and abutting extremities of the tubes of a direction (T)
transversal to the axis (A) of the tubes.
6. The method of claim 1, wherein order to heat at a distance and
without contact the two closed and abutting extremities of the
tubes, a hot air stream is used.
7. The method of claim 1, wherein order to heat at a distance and
without contact the two closed and abutting extremities of the
tubes, microwave radiation is used.
8. The method of claim 1, wherein order to heat at a distance and
without contact the two closed and abutting extremities of the
tubes, infrared radiation is used.
9. The method of claim 1, wherein order to heat at a distance and
without contact the two closed and abutting extremities of the
tubes, a laser beam and at least one of the means from the
following list are used: hot air stream, microwave radiation,
infrared radiation.
10. The method of claim 1, wherein the two closed and abutting
extremities of the tubes are heated at a distance and without
contact inside an enclosure.
11. The method of claim 1, wherein the temperature of the
extremities of the tubes is detected and the tubes are brought
closer together in function of this temperature detection.
12. The method of claim 1, wherein the extremities are initially
closed by high-frequency welding.
13. The method of claim 1, wherein subsequent to the connection of
the two tubes, traction is carried out on the connected tubes.
14. The method of claim 1, wherein the tubes are made of PVC.
15. A device for the connection of tubes and comprising abutment
means enabling two tubes to be axially aligned and brought into
abutment, and means of heating without contact, wherein the
abutment means are designed to automatically displace the two
extremities of the two tubes in abutment in a translation movement
one towards the other during the implementation of the heating
means.
16. The device of claim 15, wherein it includes optical temperature
detection means positioned close to the abutment zone of the tubes,
and the abutment means are suitable for causing a translation
movement of the tubes in function of the temperature detection
signal issued by said detection means.
17. The device of claim 15, wherein it includes a heating enclosure
and the abutment means include means for causing a translation
movement of the tubes, which are inside the enclosure.
18. The device of claim 15, wherein the abutment means include two
aligned carriages, which are mobile and guided in translation
movement, each carriage being equipped with a means for temporarily
fixing a tube on the carriage, and with actuating means enabling
the carriages to be brought closer together or further apart.
19. The device of claim 18, wherein the actuating means of the
carriages include an endless screw and a two-way motor coupled to
the screw, allowing the screw to be rotated in one or the other
sense.
20. The device of claim 18, wherein the actuating means of the
carriages include for each carriage at least one linear two-way
actuator of the elevating screw type.
21. The device of claim 18, wherein the actuating means include
elastic means constantly exercising spring forces on the carriages,
pushing them towards one other.
22. The device of claim 15, wherein the heating means without
contact include a laser source.
23. The device of claim 15, wherein the heating means without
contact include at least one hot air blowing nozzle.
24. The device of claim 15, wherein the heating means without
contact include at least a microwave source or an infrared
source.
25. Use of the method of claim 1, for connecting in a sterile
manner the closed tubes of two bags, one of which contains blood
platelets.
26. Use of the device of claim 15 for connecting in a sterile
manner the closed tubes of two bags, one of which contains blood
platelets.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of French patent
application Ser. No. 07/01014, filed Feb. 13, 2007.
FIELD OF THE INVENTION
[0002] The present invention relates to a new method and a new
device for connecting plastic tubes end to end. It is used above
all in the medical field for the sterile connection of plastic
tubes and for instance, but not exclusively, for the sterile
connection of blood bags.
PRIOR ART
[0003] In the medical field, patient treatment sometimes requires
the carrying out of blood transfusions. For this, a large quantity
of human blood platelets may be necessary to treat the patient. In
general, the quantity of blood necessary to treat a patient is much
greater than the quantity of blood contained in a bag from a single
donor. In this case, it is necessary and usual to extract the blood
(the platelets) from several bags of compatible donors and to
transfer it into a single bag of a greater size.
[0004] Each blood bag carries a tube made of thermoplastic,
generally PVC, the extremity of which is closed by squeezing the
tube and high frequency welding of the tube walls. To carry out the
transfer of the blood of the bags of compatible donors into a
single bag of a greater size, the extremities of the tubes of the
blood bags must be opened and the open extremities of these tubes
must be connected to a collector, which will distribute the blood
towards the bag of the greater size. In order to avoid
contamination of the blood and in order not to decrease the storage
life of the blood contained in the bag of the greater size, it is
important that the connection of the extremities of the tube be
carried out in a sterile manner. A sterile connection means that no
foreign body is introduced into the tubes during the connection,
that the properties of the materials used for the tubes remain
unchanged (absence of burnt areas) and in particular that air does
not penetrate inside the tubes. If all these conditions are met,
asepsis is maintained throughout the entire length of the procedure
and there can be no contamination of blood connected to the
procedure.
[0005] In the past, various solutions have been suggested to
connect plastic tubes in a sterile manner.
[0006] For instance, document U.S. Pat. No. 4,369,779 describes a
method and a device for connecting plastic tubes in a sterile
manner by using a hot cutting blade. Said hot cutting blade is
introduced simultaneously and transversally across each tube so
that the closed extremities of the tubes are cut. The tubes are
then axially aligned by sliding along the hot blade. Then, said hot
blade is retracted and the tubes are joined end to end in order to
be connected. Finally, it is necessary to carry out longitudinal
traction on each tube to open the tubes and allow the passage of a
fluid. The main disadvantage of this type of device is the use of a
consumable object, i.e. the blade, which necessarily must be
changed for each connection operation. In addition, sterility is
not guaranteed throughout the entire length of time of the
procedure. In fact, at the moment when the blade is retracted, air
or even plastic chips can penetrate the inside of the tubes and
thus contaminate the inside of these tubes.
[0007] Document U.S. Pat. No. 4,737,214 describes a method for
connecting plastic tubes in a sterile manner by using means of
heating the tubes via radiation and/or convection. To this effect,
two tubes, the extremities of which are welded, are axially aligned
in such a manner that said extremities are situated at a distance
from one another. The tubes are then crimped perpendicularly to the
welding line, and then heating means without contact are used in
the space situated between the two tube extremities. The combined
action of the heating means and the crimping allows the welding
lines of the tubes to be opened and to confer an essentially
circular shape to the tube extremities. Finally, the heating means
are retracted and the open extremities of the tubes are placed in
contact to carry out the connection of the two tubes. The advantage
of this method in comparison with that described in the previous
document lies in the fact that no foreign body can penetrate into
the inside of the tubes, since there is no cut or contact between
the tube extremities and the heating means. Nevertheless, in this
other example of the connection of plastic tubes, sterility is
still not guaranteed. In fact, the tubes are open before being
welded and even if said tubes are crimped upstream, air can
penetrate through the produced opening and contaminate the inside
of the tubes.
[0008] Document WO 03/063940 describes a laser for welding tubes
used for medical purposes. The laser is in particular used for
connecting plastic tubes. The tubes are initially spaced apart from
one another and their extremities are submitted to the action of
the laser in order to be heated. Once heated, the extremities are
moved closer and connected end to end. A disadvantage of the system
described in this document is that the laser beam must be divided
into two secondary beams, which are deviated in the direction of
the two extremities of the two tubes spaced apart. In addition, as
in the previous documents, sterility is not guaranteed since the
tube extremities are open before being joined end to end, and air
can thus penetrate into the inside of the tubes and contaminate the
latter.
[0009] Document WO 2005/102671 describes a method for connecting
tubes in a sterile manner by the use of a laser. According to the
method described, the laser can weld together the extremities of
the two tubes by joining said extremities end to end on an
absorbent film. To this effect, two tube extremities are arranged
opposite one another, their section extending essentially parallel,
and then a film absorbing the energy of the laser is placed between
the two extremities, so that the tube extremities are thus in
contact with the film. Finally, the laser is directed towards the
film and the extremities that are to be connected. The main
disadvantage of this method is that the absorbent film takes part
in the welding of the two extremities. In fact, a film residue,
which is ripped at the moment that the tubes are opened, is caught
inside the tubes. This method is complicated and delicate to
implement, and the contact between the film and the tubes prior to
the welding, as well as the film residue caught inside the tube,
compromise the sterility of the tubes.
OBJECT OF THE INVENTION
[0010] The main object of the invention is to provide a new
technical solution for the end-to-end connection of two plastic
tubes, the extremities of which are initially closed, without air
and/or foreign bodies being able to penetrate inside the tubes.
SUMMARY OF THE INVENTION
[0011] The invention thus has as a first object a method for
connecting two plastic tubes end to end, the extremities of which
are closed by compression and welding or gluing of the tube
wall.
[0012] According to this method, the two closed extremities of the
tubes are axially aligned and placed in abutment, the two closed
and abutting extremities of the tubes are heated from a distance
and without contact and the two extremities of the tubes are
axially brought together, so as to splay and weld together the
extremities of the tubes end to end, while constantly maintaining
said extremities in abutment.
[0013] Preferably, but optionally according to the invention, the
method according to the invention comprises the following
additional technical features, used individually or in combination:
[0014] to heat at a distance and without contact the two closed and
abutting extremities of the tubes, a laser beam and at least one of
the means from the following list are used: hot air stream,
microwave radiation, infrared radiation; [0015] preferably, if
using a laser beam, the latter is orientated transversally to the
compression plane of the two extremities, and simultaneously comes
into contact with the two closed and abutting extremities of the
tubes; if necessary, the laser beam scans the two closed and
abutting extremities of the tubes according to a direction (T)
transversal to the axis of the tubes; [0016] in one embodiment, the
two closed and abutting extremities of the tubes are heated at a
distance and without contact inside an enclosure; [0017] in another
embodiment, the temperature of the tube extremities is detected and
the tubes are brought closer together in function of this
temperature detection; [0018] subsequent to the connection of the
two tubes, traction is carried out on the connected tubes; [0019]
preferably, although not necessarily, the extremities are initially
closed by high-frequency welding and/or the tubes are made of
PVC.
[0020] A further object of the invention is a device for the
connection of the tubes that allows the implementation of the
method referred to above and comprises abutment means enabling the
two tubes to be axially aligned and brought into abutment, and
means of heating without contact; the abutment means are designed
to automatically displace the two extremities of the two tubes in
abutment in a translation movement one towards the other during the
implementation of the heating means.
[0021] Preferably, but optionally according to the invention, the
device according to the invention comprises the following
additional technical features, used individually or in combination:
[0022] the device comprises optical temperature detection means
positioned close to the abutment joining zone of the tubes, and the
abutment means are suitable for causing a translation movement of
the tubes in function of the temperature detection signal issued by
said detection means: [0023] the device comprises a heating
enclosure and the abutment means include means for causing a
translation movement of the tubes, which are inside the enclosure;
[0024] the abutment means include two aligned carriages, which are
mobile and guided in translation movement, each carriage being
equipped with a means for temporarily fixing a tube on the
carriage, and with actuating means enabling the carriages to be
brought closer together or further apart; [0025] in a first
embodiment, the actuating means of the carriages include an endless
screw and a two-way motor coupled to the screw, allowing the screw
to be rotated in one or the other sense; [0026] in a second
embodiment, the actuating means of the carriages include for each
carriage at least one linear two-way actuator of the elevating
screw type; [0027] in a third embodiment, the actuating means
include elastic means constantly exercising spring forces on the
carriages, pushing them towards one another; [0028] preferably, the
heating means without contact include a laser source and/or at
least one hot air blowing nozzle and/or a microwave source and/or
an infrared source.
[0029] A further object of the invention is the use of the method
or the device referred to above to connect in a sterile manner the
closed tubes of two bags, one of which contains blood platelets or
another fluid requiring the same asepsis conditions.
BRIEF DESCRIPTION OF DRAWINGS
[0030] The invention and its advantages will appear more clearly
upon reading the following description of a non-limiting and
non-exhaustive example and with reference to the accompanying
drawings, in which:
[0031] FIG. 1 shows a diagram of the connection of the blood bags
to a collector used in the medical field of blood transfusion,
[0032] FIG. 2 is a perspective view of an example of a plastic
tube, the extremity of which is closed in an airtight manner, by
compression and welding (or gluing) of the tube wall,
[0033] FIG. 3 is a perspective view of a first embodiment of a
device according to the invention,
[0034] FIG. 4 is a top view of the device of FIG. 3, the hot air
heating means not being represented,
[0035] FIG. 5 is a frontal view of the device of FIG. 3, the hot
air heating means not being represented,
[0036] FIG. 6 is a block diagram of the electronic means enabling
the functioning of the connecting device to be automatically
controlled (control of the laser and the hot air heating means and
control of the movement of the carriages),
[0037] FIGS. 7 and 8 represent two tubes mounted on the device of
FIG. 3 (only the carriages and clamping means are represented) in
an intermediate position of the method (the phase when the
carriages are brought closer together),
[0038] FIGS. 9 and 10 represent two tubes mounted on the device of
FIG. 3 (only the carriages and clamping means are represented) in a
final position of the method,
[0039] FIGS. 11 and 12 represent two tubes that are axially aligned
and in abutment,
[0040] FIGS. 13 and 14 represent two tubes in abutment in the phase
when the carriages of the device of FIG. 3 are being brought closer
together,
[0041] FIGS. 15 and 16 represent two tubes connected end to end,
upon completion of the connecting method according to the
invention,
[0042] FIG. 17A is a perspective view of a second embodiment of a
device according to the invention,
[0043] FIG. 17B is a perspective view of a third embodiment of a
device according to the invention,
[0044] FIGS. 18 to 23 illustrate additional and optional steps for
implementing secondary extremity welds, perfectly calibrated and
controlled, replacing the initial extremity welds.
DETAILED DESCRIPTION
Application Example
Sterile Connection of Bags Containing Blood Platelets (FIGS. 1 and
2)
[0045] One of the preferred, but non-exclusive and non-limiting
applications of the invention can be found in the medical field of
blood transfusion, and consists in the sterile connection of bags
containing concentrates of blood platelets. The degree and
requirement of sterility varies according to the applications
(medical, food processing, . . . ). It is in the medical field of
blood transfusion, however, that the degree and requirements are
the highest. It is thus imperative that asepsis be preserved.
[0046] To treat a patient it is sometimes necessary to carry out
blood transfusions. For this, a large quantity of human blood
platelets may be necessary to treat the patient. In general, the
quantity of platelets necessary to treat a patient is much greater
than the quantity of platelets contained in a bag from a single
donor. In this case, it is necessary and usual to extract the
platelets from several bags of compatible donors and to transfer
them into a single bag of a greater size.
[0047] By way of example, FIG. 1 shows four intermediate bags P1,
P2, P3 and P4, each containing a concentrate of platelets, a bag P5
usually referred to as a collector, and a final bag P6 with a
greater capacity than the intermediate bags P1 to P4. The collector
P5 is connected to the final bag P6, a filter F being preferably
placed between the collector P5 and the final bag P6.
[0048] Each intermediate bag P1 to P4 includes a flexible tube 11
of a thermoplastic material, the extremity 111 of which is closed
in an airtight manner by compression and high-frequency welding of
the wall of the tube 11. The collector P5 includes four flexible
tubes 12 enabling it to be filled. The extremity 121 of each tube
12 is closed in an airtight manner by compression and
high-frequency welding of the wall of the tube 12.
[0049] The compressed and welded extremities 111, 121 of the tubes
11, 12 are shown in more detail in FIG. 2. In this FIG. 2, and in
the continuation of the description, the compression plane of the
extremities 111, 121 is shown by reference (P), and the extremity
welds of the tubes 11 and 12 are referenced as 112 and 122,
respectively. These zones 112, 122, flattened and welded to the
extremity of the tubes 11, 12, extend over a width (I) in the axial
direction (A) of the tube, along a length (L) and with a very
limited thickness, which is sufficient for hermetically sealing the
extremity of the tube.
[0050] To carry out the transfer of the concentrates of platelets
from the intermediate bags P1 to P4 to the bag P6 with the greater
capacity, the intermediate bags P1 to P4 must be connected to the
collector P5. To connect one intermediate bag P1, P2, P3 or P4 to
the collector P5, the closed extremity 111 of the tube 11 of this
intermediate bag must be opened, as well as the closed extremity
121 of one of the tubes 12 of the collector P5, and the open
extremities of these two tubes 11 and 12 must be connected end to
end. In FIG. 1, the tube 11 of the bag P3 is connected end to end
with one of the tubes 12 of the collector P5.
[0051] In order to avoid contamination of the blood platelets
transferred to the bag with the greater capacity P6 and in order
not to decrease their storage life, it is important that the
connection of the extremities of the tubes 11, 12 be carried out in
a sterile manner. A sterile connection means that no foreign body
is introduced into the tubes 11, 12 during the connection, that the
properties of the material of the tubes 11, 12 remain unchanged
(absence of burnt areas) and in particular that air does not
penetrate inside the tubes 11, 12. If all these conditions are met,
asepsis is maintained throughout the entire length of the procedure
and there can be no contamination of the blood platelets.
Device for Connecting the Tubes
Structure--First Embodiment (FIGS. 3 to 6)
[0052] FIGS. 3 to 6 show a first embodiment of a device 1 of the
invention, designed to be used to carry out the end-to-end
connection of closed tubes 11, 12. This device 1, the structure and
functioning of which will be described in more detail hereafter,
advantageously enables this connection operation of the tubes 11,
12 to be carried out in a sterile manner, in a short time and
without requiring the use of consumable tools, in particular for
the opening of the tubes 11, 12.
[0053] This device 1 is advantageously used in the medical field of
blood transfusion for the connection of tubes 11, 12 of bags during
a previously mentioned transfer operation of blood platelets.
[0054] More generally, the device of the invention can be used in
any application where it is necessary to connect two plastic, and
more particularly thermoplastic, tubes end to end, the respective
extremities 111 and 121 of which are initially closed by
compression and welding or gluing of the wall of the tube. The
invention is not limited to tubes closed by HF welding, but can
also be applied to any plastic tube with an extremity closed by
compression and welding or gluing of the wall of the tube, and able
to be opened by heating.
[0055] With reference to FIGS. 3 to 6, the tube connection device 1
comprises two mobile carriages 6 and 7, means of heating via a hot
air stream 3, a laser source 3' [FIG. 6] suitable for producing a
laser beam FL, a pyrometer 2 and means for actuating the carriages
6, 7 including in particular electronic control means 8 [FIG. 6].
On FIGS. 3 and 4, the laser source is not represented, and only the
laser beam FL produced by means of this laser source has been
represented. The laser source FL is designed to be applied to the
extremity welds 112, 122 of the two tubes 11 and 12, in order to
heat said welds and in particular to enable the extremities 111,
121 of the tubes to be opened. This laser beam FL is orientated
transversally to the compression plane (P) of the two extremities
111, 121 and simultaneously comes into contact with the two
extremities 111, 121 of the tubes 11, 12, which are closed and
placed in abutment. The wavelength of the laser radiation is chosen
in function of the type of material constituting the tubes 11, 12,
so that the energy supplied by the laser beam FL is absorbed in an
efficient manner by the walls of the tubes 11, 12. The power of the
laser will be chosen in particular in function of the desired speed
of action for the laser.
[0056] The diameter of the laser beam FL is preferably inferior or
equal to the width (I) of the welds (for instance 1 mm), but
generally inferior to the length (L) of the welds 112, 122. In this
case, it is preferable that the laser beam FL scans the welds 112,
122 of the tubes 11, 12 according to their length (L), namely with
reference to FIG. 5 in the direction T transversal to the axis A of
the tubes 11, 12. This scanning is carried out over all or part of
the length L. The laser fitted to the device 1 displays for
instance a scanning frequency of the welds 112, 122 of 0.5 Hz,
namely the laser beam FL carries out a return scan on the welds
112, 122 in two seconds.
[0057] The two carriages 6 and 7 are mounted on an endless screw 13
and are translationally movable along this endless screw. This
endless screw 13 is driven to rotate on itself by a motor. The
rotation of the endless screw 13 in one sense triggers the coming
together of the two carriages 6, 7 and the rotation of the endless
screw in the other sense triggers the spacing apart of the two
carriages 6, 7 at a speed depending in particular on the speed of
rotation of the endless screw 13. The carriages 6, 7 are equipped
with clamping means 61, 71, which enable the extremities of the
tubes 11, 12 to be temporarily fastened onto the carriages and, if
necessary, liquid contained inside the extremities 111, 121 of the
tubes 11, 12 to be removed prior to the connection operations. The
two carriages 6, 7 and their clamping means 61, 71 are aligned so
as to enable the tubes 11 and 12, which are to be connected, to be
axially aligned.
[0058] The hot air heating means 3 include two blowing nozzles 30,
which are supplied with hot air. These nozzles 30 open in the
proximity of the connection zone of the tubes 11, 12. This stream
of hot air enables the heating of the extremities 111, 121 of the
tubes 11, 12 to be accelerated and thus the time of the tube
connection cycle to be reduced.
[0059] The pyrometer 2 is a captor enabling the temperature of the
tubes to be detected without contact and in an optical manner
(generally via infrared detection). Preferably, the pyrometer 2
used in the device 1 is compact and mounted in proximity to the
connection zone of the tubes 11, 12. The temperature detected by
this pyrometer is an average temperature taken in the field of
vision of the pyrometer, the walls of the extremities 111, 121 of
the tubes 11, 12 being comprised in the field of vision.
[0060] With reference to FIG. 6, the electronic control means 8 of
the device 1 receive the incoming temperature detection signal 2a
supplied by the pyrometer 2 and enable the heating means to be
controlled (laser source 3' and supply of hot air from the blowing
nozzles 30 of the hot air heating means 3, as well as the motor (M)
enabling the endless screw 13 to be rotated in one or the other
sense (for the translational movement of the carriages 6, 7). These
electronic control means 8 include a programmable control unit
(implemented for instance by means of a microprocessor), designed
to carry out automatically a control programme stored in its
memory. The automatic carrying out of this control programme
enables the control means 8 to command the heating means (laser and
hot air supply from the blowing nozzles 30) and the movement of the
carriages 6, 7 in function of the temperature detected by the
pyrometer 2. An example of a control programme is detailed
hereafter.
Implementation and Functioning of Connection Device
[0061] A particular example of the implementation and functioning
of the above connection device 1 for connecting two tubes 11, 12
end to end will be detailed with reference to FIGS. 3 to 16. FIGS.
11 to 16 represent the principal stages of the connection method,
but only the tubes 11 and 12 are represented in order to improve
the clarity and understanding of the method.
[0062] To connect two closed tubes 11, 12 end to end, by means of
the device 1, the following steps are carried out:
1.sup.st Step
[0063] Each tube 11, 12 is positioned on a carriage 6, 7 and
temporarily fastened to the carriage via clamping means 61, 71. As
shown on FIGS. 3 to 5 and FIGS. 11 and 12, the two tubes 11 and 12
are axially aligned and abutting, their closed extremities 111 and
121 in contact one with the other. To accelerate the procedure,
prior to this step or during this step, the hot air heating means
can be started.
2.sup.nd Step
[0064] The laser and the hot air heating means 3 are started (hot
air supply from the blowing nozzles 30), enabling the triggering of
a heating without contact of the closed and abutting extremities
111, 121 of the two tubes 11, 12 with, if necessary, a scanning by
the laser of the extremity welds 112, 122 of the two tubes 11,
12.
[0065] This first heating step is continued until the temperature
measured by the pyrometer 2 reaches a first predefined temperature
threshold (T1).
3.sup.rd Step
[0066] When the temperature measured by the pyrometer 2 reaches the
first temperature threshold T1, the control means 8 command the
motor (M) driving the endless screw 13 so as to bring the two
carriages 6, 7 closer to one another at a predefined speed V1.
[0067] This heating step is continued until the temperature
measured by the pyrometer 2 reaches a second predefined temperature
threshold T2 (T2>T1).
4.sup.th Step
[0068] When the temperature measured by the pyrometer 2 reaches the
second temperature threshold T2, the control means 8 command the
motor (M) driving the endless screw 13 so as to bring the two
carriages 6, 7 closer to one another at a predefined speed V2,
superior to the above speed V1.
[0069] This heating step is continued until the temperature
measured by the pyrometer 2 reaches a third predefined temperature
threshold T3 (T3>T2).
5.sup.th Step
[0070] When the temperature measured by the pyrometer 2 reaches the
third temperature threshold T3, the control means 8 stop the motor
(M) (immobilisation of the carriages 6 and 7), stop the laser and
cut the hot air supply from the blowing nozzles 30.
[0071] During the above heating steps, the closed and abutting
extremities 111, 121 of the two tubes 11, 12 are heated until the
glass transition temperature of the material is reached, for
instance between 130.degree. C. and 150.degree. C. for PVC. The
glass transition temperature corresponds to an augmentation in
viscosity of the tube, which nevertheless enables the shape of the
tube to be maintained.
[0072] The localised heating by laser and hot air stream of the
abutting extremities 111, 121 of the two tubes 11, 12 alters the
two extremity welds 112, 122 and triggers the softening of the
material at the level of the extremities of the tubes 11, 12.
[0073] The bringing together of the carriages 6 and 7 during the
course of the above 3.sup.rd and 4.sup.th steps enables in a first
instance the shrinkage of the material ensuing from the softening
of the material to be compensated for, and the tubes 11, 12 to
remain constantly abutting (FIGS. 7, 8 and FIGS. 13, 14); in a
second instance, the bringing together of the carriages 6 and 7
enables the two tubes 11, 12 to be brought sufficiently close to
one another by exercising a pressure enabling a connection 9
between the tubes 11 and 12 to be formed (FIGS. 9, 10 and FIGS. 15,
16). The pressure exercised during this bringing together of the
two tubes 11, 12 enables the two abutting extremities 111, 121 of
the two tubes 11, 12 to be splayed and thus plays a part in the
opening of the tubes 11, 12 (loosening of the extremity welds).
[0074] Generally, upon completion of the above 5.sup.th step, the
two tubes 11, 12 connected end to end communicate together,
enabling the passage of a fluid inside the tubes 11, 12.
Nevertheless, in certain cases, owing to the initial compression of
the extremities 111, 121 of the tubes 11 and 12, it can happen that
a fine film is created at the level of the connection 9 during the
opening of the tubes 11, 12, thus blocking said tubes 11, 12. To
remedy this problem, the procedure can include an additional step
subsequent to the welding of the two tubes in which the abutment
means are in action, via actuating means on the carriages 6, 7 so
that the carriages 6, 7 are slightly moved apart. This moving apart
has the effect of exercising traction on the two tubes 11, 12
connected end to end, said traction being sufficient to tear said
film and thus freeing up the passage for a fluid, without
disconnecting the two tubes.
[0075] Upon completion of the procedure, the two tubes 11 and 12
are connected end to end, as illustrated in FIGS. 15 and 16, and
communicate together, enabling a fluid to pass from one tube to the
other.
[0076] The temperature thresholds T1, T2, T3 and the speeds of
movement of the carriages V1 and V2 are determined on a
case-by-case basis by the person skilled in the art, such as to
obtain the end-to-end connection of the tubes 11, 12 by maintaining
the two extremities 111, 121 of the tubes 11, 12 in constant
abutment. This maintaining of the abutment is important, since it
enables a contamination of the inside of the tubes 11, 12 to be
avoided, in particular with air from outside the bags, and
contributes to maintaining the sterility and asepsis of the tubes
11 and 12.
[0077] By way of a non-limiting example of the invention, in a
specific embodiment, the connection device 1 has been used to
connect end to end tubes 11, 12, identical to those shown in FIG.
2. The tubes 11 and 12 were made of PVC; the external diameter (D)
of the tubes 11, 12 measured approximately 4 mm and the internal
diameter (d) of the tubes measured approximately 3 mm. The HF welds
112, 122 at the extremity of the tubes 11, 12 were carried out in a
zone extending across a width (I) of 1 mm in the axial direction of
the tube, along a length (L) of 8 mm, and with a depth measuring
0.5 mm.
[0078] The laser fitted to the device 1 was designed to emit the
range of wavelengths between 1.5 and 2.1 .mu.m, with a power of 2 W
to 3 W. The hot air blown by the nozzles 30 was brought up to a
temperature comprised between 400.degree. C. and 650.degree. C.
[0079] The pyrometer 2 used was the infrared captor without contact
marketed by the company CALEX with the reference EL21 and was
suitable for detecting temperatures superior to 15.degree. C. with
a precision of +/-1.degree. C. and with a rapid response time at
the rate of 200 ms. The pyrometer 2 was situated at approximately 5
cm from the connection zone of the tubes 11, 12, between the two
carriages 6, 7 and the diameter of the temperature measurement zone
measured 35.5 mm.
[0080] The temperature thresholds T1, T2 and T3 measured 31.degree.
C., 40.degree. C. and 43.degree. C., respectively. The set speeds
V1 and V2 measured 150 .mu.m/s and 200 .mu.m/s, respectively.
[0081] The implementation of a heating by laser advantageously
enables a localised heating of the extremity welds 112, 122 of the
tubes to be obtained, acting directly on the centre of the
material, enabling a more efficient and more rapid destruction
through heating of the welds 112, 122. The injection of a hot air
stream in combination with the laser enables the procedure to be
accelerated, in particular to obtain the end-to-end welding of the
tubes.
[0082] Nevertheless, the invention is not limited to the
implementation of a laser combined with a hot air stream. It can be
envisaged to use for instance a laser only or hot air only. More
generally, any known means of heating can be used (by radiation, in
particular microwave or infrared radiation and/or convection),
enabling the extremities of the tubes to be heated at a distance
and without contact.
[0083] FIG. 17A shows a further embodiment of a device according to
the invention, different from the above embodiment of FIGS. 3 to 5,
due to the implementation of an enclosure E and heating means 30a,
30b of the inside volume of the enclosure. The driving means
(carriages 6, 7) of the tubes are located inside this enclosure E.
This enclosure E is preferably but not necessarily closed in an
airtight manner, with the exception of the two opposite openings
enabling the passage of tubes 11, 12. The heating means of the
enclosure include a blowing nozzle 30a supplied with hot air and a
sucking nozzle 30b. These nozzles 30a and 30b open into the inside
of the enclosure E opposite one another and in proximity of the
abutment zone of the extremities 111, 121 of the tubes 11, 12. The
blowing nozzle 30a, when supplied with hot air, enables hot air to
be introduced inside the enclosure E, and the sucking nozzle 30b
enables the air contained inside the enclosure E to be recycled
towards the outside of the enclosure E. When operating, these
nozzles 30a, 30b enable a hot air stream to be created in the
abutment zone of the tubes inside the enclosure E, and to increase
the air temperature inside the enclosure E. The enclosure E also
includes a window F, transparent for the laser beam FL (for
instance a quartz window).
[0084] In an advantageous manner according to the invention, the
inside volume of the enclosure can be preheated by the injection of
a hot air stream by means of nozzles 30a, 30b and before the
introduction into the enclosure E of the two tubes 11, 12 to be
connected. This preheating ensures not only the elimination of all
the bacteria that may be found inside the enclosure E, but also the
reduction in length of time of a connection cycle of the two tubes
11, 12.
[0085] In the embodiments that have just been described, the
actuating of the carriages 6, 7 is controlled in function of a
temperature measured by means of a pyrometer 2. On the one hand,
this pyrometer 2 can be replaced by any other known equivalent
temperature measuring device, for instance by a thermal camera
connected to the control means 8.
[0086] In addition, the implementation of a temperature control by
means of a thermal captor 2 is preferable but nevertheless not
indispensable. In a further embodiment, the control means 8 can for
instance be programmed to control the movement of the carriages
with predefined cycle times. For instance, the length of time of
the 2.sup.nd, 3.sup.rd and 4.sup.th steps can be predefined. In
this case, the use of a temperature captor 2 is not necessary.
[0087] The abutment means of the two tubes do not necessarily
include two carriages 6, 7 that are movable in translation, said
carriages 6, 7 being able to be replaced by any equivalent means
enabling two tubes to be abutting and these two tubes to be moved
in translation, one towards the other, while maintaining the two
tubes in abutment.
[0088] The means of translationally moving the carriages (endless
screw 13, motor M) can be replaced by any other means enabling the
two carriages 6, 7 to be brought together or moved apart.
[0089] In particular, the movement of the carriages 6, 7 can be
commanded by the control means 8 by means of any linear two-way
actuator. For instance, with reference to FIG. 17B, in a further
embodiment the two carriages 6, 7 are mounted and slide in
translation on a fixed guiding shaft 4, and the two carriages 6, 7
can be moved along this shaft 14 by means of two-way electric
elevating screws 15. These elevating screws 15 are commanded by
electronic control means 8.
[0090] In a further, simpler embodiment, the device does not
necessarily include electronic control means 8 and the movement of
the carriages 6, 7 is controlled in a purely mechanical manner. For
instance, the two carriages 6, 7 can be guided in translation by
being mounted on a non-rising spindle or equivalent, and the
actuating means of the carriages include elastic means (for
instance restoring springs) exerting constant spring forces on the
carriages 6, 7, pushing them towards one another. In this case,
during the softening of the material resulting from the heating of
the abutting extremities 111, 121 of the two tubes 11, 12, the
springs mechanically push the two tubes 11, 12 towards one another,
while maintaining them constantly abutting.
[0091] In certain cases, the welds 112, 122 at the extremity of the
tubes 11, 12 can be carried out in too strong a manner (too great a
welding depth and/or too great a welding surface (I.times.L)),
which in a prejudicial manner can slow down the connection
procedure, with the length of duration of heating of the welds
needing to be increased.
[0092] To offset this problem, in one embodiment of the invention,
prior to the above 1.sup.st step, the following additional
operations can be carried out, which will be described with
reference to FIGS. 18 to 23.
[0093] Firstly, two secondary HF welds 112', 122' (FIGS. 20 and 21)
are carried out on the two tubes 11, 12, which are closed by
extremity welds 112, 122 (FIGS. 18 and 19). These two welds 112',
122' are carried out in a perfectly controlled manner, and in a
less strong manner than the original welds 112, 122, sp as to
reduce the requirement of an ulterior unwelding. Obviously, these
secondary welds 112', 122' must nevertheless be sufficient to
ensure an airtight closing of the tubes 11, 12.
[0094] Once the secondary welds 112', 122' have been carried out,
the extremities of each tube 11, 12 are cut, for instance by means
of a cutting blade or a laser, at the level of the secondary welds
112' and 122', and the extremity portions 113 and 123 of the two
tubes 11, 12 including the original welds 112, 122 are removed.
[0095] Then the above steps of the method of the invention can be
implemented as described above (1.sup.st step, 2.sup.nd step, . . .
) on the tubes 11 and 12 closed by extremity welds 112', 122'.
[0096] If necessary, prior to carrying out the secondary welds
112', 122', it may be necessary to clamp the tubes 11 and 12 with
the aim of removing liquid contained in the extremities of the
tubes 11 and 12.
* * * * *