Apparatus for manufacturing plastic bags with connection nipples

A method is disclosed for the continuous manufacture under sterile or at least non-pyrogenous conditions of plastic bags provided with connecting nipples to be used for the storage of blood plasma or serum, milk and other vulnerable liquids. For the welding of connecting nipples to the outer wall of the bag a counter-electrode is employed and is inserted into the bag's interior. Normally the plastic bags are formed out of an extruded plastic tube after it has been flattened and coiled to a spool. The present method starts from a wider flat tube than that used in the prior art and which has a width equal to the length dimension of the bag to be made so the bag is open at its sides. A counter electrode formed as a sliding-block is located in the interior of the tube whose leading end is closed now. The sliding-block is displaced in a direction towards the spool and each time that the welding of the connecting nipples onto a given bag is completed, the sliding-block is passed to the next bag to be treated. The bag just treated is then closed along its sides so that sterile conditions can be maintained. Piercing through said wall portion of the bag can be deferred till the bag is actually taken in use. However, piercing can also be done during manufacture by means of a sharp-pointed needle or plunger being slidable in a bore within the sliding-block. The nipple can have virtually any shape. The most simple form is a length of narrow hose which is to be shut off by a clip. In another form the nipple is of the flange type with the flange serving as a seat for a droplet counter, for instance.

This invention relates to a method and apparatus for the continuous and 
non-pyrogenous manufacture of plastic bags provided with connection 
nipples as well as the article produced thereby. 
A frequently used material for the manufacture of lightweight, transparant 
bags for transfusion and infusion purposes, is polyvinylchloride that 
emanates from the extruder as a relatively small tube and which is then 
wound in a flat condition into a coil. Alternatively, two sheets of 
plastic foil have been used. 
In the prior art method the flat tube was uncoiled and cut into pieces of 
equal length along transverse cutting lines at the leading and trailing 
end of each piece as viewed in the extrusion direction of the flat tube. 
The uncoiled and cut pieces were provided, through several operations, 
with various connecting nipples and with an end weld and a sealing weld at 
their leading end. 
Prior to the provision of the connecting nipples in the cut tube piece, a 
mandrel or core pin had to be inserted through the open trailing end, 
which eventually constitutes the upper end of the bag. The nipples were 
applied near the closed leading end, which eventually constitutes the 
lower end of the bag. Then the core was withdrawn and this had to be done 
through the open upper end. The movement of the core was therefore a 
reciprocal one. Only when short nipples or narrow hose ends were to be 
welded could the welding operation take place from the exterior. 
Thereafter a sealing weld and an end weld were applied at the upper end of 
the bag. Due to the presence of a closing seam on the lower end of the bag 
the nipples could never be arranged at the lowermost end, viz. the middle 
region of the bottom of the bag and therefore could not point entirely 
perpendicularly downwards but instead, extend somewhat sideways from the 
bag in an inclined position. 
Other disadvantages of the known method relate to the necessity of 
splitting open the walls of the tube piece for the insertion of the core 
pins and for the welding of the connecting nipples or hose ends. This 
opening action was very difficult due to the strong adherence of the two 
walls of the extruded tube being in flat, folded condition when coiled on 
a spool. In addition there was a need, in the prior art for the subsequent 
treatment of purifying and sterilizing each bag through rather expensive 
after-controls. The purification includes rinsing the bag with a 
desinfecting liquid. This involves many decades of liters of rinsing 
liquid, rendering said rinsing operation time consuming. 
In the past it has been proposed to start from a wider extruded tube, which 
in a flat, folded condition can have such a width that the bag can be 
taken and made out of the transverse dimension of the tube. Thus, with 
respect to the previous method the tube material, when viewed in the 
extruded direction, is turned 90.degree.. The upper and lower end weld 
then fall in the two original side folds of the tube. As in the previous 
method the leading end, forming one of the bag sides, was sealed and the 
trailing end left open. It was usual that during further processing of 
this wide tube one of its side folds was cut open to facilitate the access 
to the interior of the bags for the insertion and manipulation of the core 
pins to and from the welding areas, where the nipples were affixed. It is 
clear that, utilizing the prior art method, a non-pyrogenous production is 
impossible. 
In the present method the latter process is followed but without it being 
necessary to cut open a side fold. 
The present method is characterized in that starting from a flat, folded 
extruded tube, in which is inserted a relatively displaceable 
sliding-block, the leading end of the tube is closed and the connecting 
nipples are affixed on the wall of the bag by thermal or high frequency 
welding. The sliding-block cooperates as low electrode, with an upper 
electrode and, after having moved the sliding-block, upper and lower end 
welds along the side folds and sealing welds and cutting lines along the 
transverse sides are provided. The sliding-block is a core of, for 
example, rectangular shape which, by means of a roller mechanism or smooth 
sliders is retained such that the tube can be moved with respect to the 
core. Because of the shape of the core, the tube assumes a rectangular 
shape, so that the core can be used for welding operations and can serve 
as a carrier, if any of the core pins are movable in the interior of the 
tube. While it is, in principle, possible with such a rectangular 
sliding-block to use any of the six sides faces as a supporting face and 
simultaneously as lower electrode for the welding of connecting nipples, 
the side face engaging the definite bottom of the bag will be employed 
most frequently as the supporting face. For the welding operation it is 
therefore no longer necessary to cut the tube piece open beforehand. On 
the contrary, since it is not necessary to insert a core each time and to 
withdraw it thereafter, the leading end of the flat tube to be uncoiled 
can be closed and if the core has initially been introduced in a sterile 
manner, the sterile conditions can be maintained, although not sterile in 
an absolute sense but at least non-pyrogenous during the welding of the 
connecting nipples, and during the welding of the end welds and sealing 
welds along the four sides, in which of course the core has beforehand 
been pushed backwards in a direction opposite to the conveying direction 
of the tube. All connecting nipples are still closed so that the sterility 
resp. pyrogen freedom is maintained until the moment that the bag is put 
into use and is filled in a sterile manner with sterile liquids, such as 
blood plasma, physiological solutions and similar infusion liquids, with 
mild or other liquid diary products or in general with substances for 
which a pure or chemically pure package is very important. In this 
connection as a further application of the invention the packaging of pain 
or similar liquids in these bags can be considered. The connecting nipples 
can be used both for filling and for tapping purposes. 
The connecting nipples themselves can also be welded on in a sterile 
condition. When, according to the present invention, the connecting 
nipples are taken off from an extruded, endless narrow hose in the form of 
hose pieces of arbitrary length, of which the trailing end is cut by means 
of a high frequency or thermal cut-welding. Each time a certain length of 
hose is cut off the next piece is fused so that the non-pyrogenous 
conditions are maintained continuously. 
If the shape of the connecting nipple does not lend itself to being taken 
off from an endless hose, the nipples should be made separately. With the 
machine according to the present invention a number of nipples can be 
welded simultaneously to a number of bags. 
It is possible to utilize the present invention such that the hose end is 
cut off only shortly before the welding-on operation when it is pressed on 
the welding-core, so that contact with the non-sterile atmosphere is very 
short. Alternatively, the wall of the bag is kept intact till the bag is 
definitely taken in use. With long hose ends this is of course not 
possible and so the first manner has to be chosen. That means pincing 
through just before the welding-on operation. There are various ways to 
convey the core within the interior of the tube such as by gravity, by 
means of vertical rollers, by means of horizontal rollers and by means of 
a core being coated wholly or partly with low friction material, such as 
teflon to keep the friction as low as possible. 
The invention also relates to a sliding block fulfilling the above 
requirements and those to be explained herebelow. 
When pulling-through the tube, the external rollers or sliders and the core 
remain in place so that periodically the tube is drawn over the core, 
irrespective of whether the core is in a horizontal or a vertical 
position. When the core contains magnets, it can be conveyed by external 
magnets, or kept in place while the tube is being displaced. 
In the core block, provision can be made to establish a movement, so that a 
plunger can be moved mechanically or magnetically within the core block. 
The plunger then pierces the part of the bag wall that remains as a 
membrane, if it was after the welding-on of a connecting nipple. 
Advantageously a number of core pins, designed for different bags, can be 
actuated simultaneously by a pressure exerted from the exterior on the 
opposite end of the pin(s). 
Provision is also made for welding of tube connectins or needle connectors 
extending inwardly. This is established by means of a counter matrix or 
counter electrode moving within the sliding block. 
The invention is further related to a machine for carrying out the present 
method. 
The invention relates also to a plastic bag manufactured in accordance with 
the present method. 
Moreover the invention relates to a plastic bag provided with one or more 
connecting nipples welded in the folding line, which is thus in the middle 
of the bottom of the bag.

In FIG. 1, a known method for the manufacture of plastic bags 1 is 
illustrated. The bags are manufactured from a continuous, flat folded 
extruded plastic tube 2 that moves in the direction shown by arrow 3. The 
tube is cut along cutting lines 4, whereby each bag 1 is provided at one 
side or upper end with a sealing weld 6 (FIG. 2). The bag is then still 
open at one end, viz. the opposite or bottom end 7. From the end 7 a core 
or core pins are inserted prior to welding-on connecting nipples 8 (FIG. 
2) at some distance above the bottom end 7. Next, the core is pulled out 
of the bag 1 and the lower end 7 is provided with a sealing weld 9 and end 
weld 11. At the same time the upper side or end 6 is provided with a 
sealing weld 12. In the sealing weld 12 at the upper end 6 an opening 13 
is provided so that the bag 1 can be suspended. 
In FIG. 3 the principle of the method according to the present invention is 
illustrated. According to the present invention, bags 21 are not taken out 
of the length but out of the width of a flat tube 22. An example of the 
finished bag 21 is shown in FIG. 4. The upper and lower end welds 24 and 
26 respectively are now arranged in the side folds of the tube 22 so that 
sealing welds can be disposed of. These are now provided transversely to 
the direction of movement shown by arrow 23 of the tube 22 as side sealing 
welds 29 and 31. In the end weld 24 of the upper side fold is also 
provided an opening 33. The connecting nipples 28 are completely arranged 
in the bottom end 27. 
The foregoing construction of the bags 21 can be accomplished with a 
sliding block 34 in the interior of the flat tube 22, as shown in FIG. 5. 
It is shown in FIG. 5 that the tube 22 is wound from a coil 36 and the 
portion of the tube opened by the sliding block 34 is limited by upstream 
and downstream roller mechanisms 37 and 38 respectively. The roller 
mechanisms 37 and 38 are stationary (although rotatable) and cause the 
tube 22 to be pulled over the sliding block 34. 
Instead of rollers smooth sliders 38 could also be used for this purpose, 
as shown in FIG. 6. In the bottom side 41 of the sliding block 34 openings 
42 are provided, through which the tips of the core pins can project. 
In FIG. 7 a portion of a longitudinal section of a sliding block 34 is 
shown, in which holes 43 are provided coaxially with the openings 42. A 
plunger or core pin 44 terminating in a tip 46 which can project through 
the opening 42 is located in the holes 43. There is also provided, 
opposite the side of the pin 44, remote from the pin tip 46, a 
piston-cylinder-system 47 that is arranged outside the bag 21, the system 
47 being located in such a position that the piston stem 48 is already in 
contact with the plunger 44 to thereby locally depress slightly the 
material of the bag 21. 
In front of the pin tip 46 there is a connecting nipple 28 which is to be 
welded-on to the bottom end 27 of the bag 21. The nipple 28 is located in 
an opening in a die 49 with the surface of the die 49 that is adjacently 
opposite the pin tip 46 being generously rounded as designated by the 
reference character 51, whereby the material of the bag 2 and that of the 
nipple 28 fuse smoothly into each other during the welding process. During 
this operation the bottom end 27 of the bag 21 is pinched through by the 
pin tip 46 in the vicinity of the nipple 28 so that this material also 
fuses with the weld being formed. 
In FIG. 8 is shown, on a slightly larger scale, a more complete die 49 and 
also a detail of the pin tip 46 which is also provided with a generously 
rounded shoulder that cooperates with the rounded portion 51 in order to 
facilitate the fusing into each other of the materials to be welded 
together. The die 49 is formed by a metal top plate 52 and a metal bottom 
plate 53, between which insulating material 54 is provided. The plates 52 
and 53 are connected mechanically and, also in a high frequency welding 
current conductive way by bolts 56. 
In FIG. 9 there is schematically shown the manner in which a number of 
piston-cylinder-systems 47 can be simultaneously operated, when the 
sliding block 34 extends over a length of four bags. 
In FIG. 10 is shown a specially formed nipple 58 being welded to a bag 21. 
It will be evident that this particular form does not offer any problem in 
the present method and that virtually each form can be welded with the 
method of this invention. The form deviating from a smooth nipple, such as 
nipple 28, provides that this nipple cannot be cut from a continuous hose, 
but rather each such nipple should be manufactured separately. Putting 
these nipples 58 near the bottom 27 of the bag 21 is, however, effected 
completely automatically by means of a swinging mechanism. The nipples 58 
are slid on a hinged pin 59 that is fixed on a slide 61. By swinging 
around an axis 62, the nipple 58 is brought to the desired position. 
Thereafter, the slide 61 is withdrawn by means of a piston-cylinder-system 
63 with the slide 61 moving along rails 64. By means of dotted lines in 
FIG. 10, it is made clear that this construction is also suitable to 
simultaneously operate a number of pins 59 about axis 62. 
FIG. 11 shows the application of a flanged nipple 68 for the mounting of a 
droplet-counter 69. For this purpose an adaptor 71 is inserted into the 
nipple 68 and the droplet-counter 69 comes to rest on a flange 72 and is 
supported with the plunger-like lower part 73 of the droplet-counter 69 in 
the nipple 68. The lower face 74 of the plunger 73 extends to a position 
near and in opposition to a membrane 76 present in the nipple 68. The 
upper part 77 of the adaptor 71 a tapered plug-like member 78 with a 
droplet needle 79 and a feed tube 81 are arranged whereby the sharp point 
82 of the droplet needle 79 pierces through the membrane 76. By means of 
dotted lines in FIG. 11 a prior construction of a nipple is indicated, 
whereby the injection needle 89 was not guided and supported during the 
piercing of the wall so that it can easily pierce through a spot of the 
wall of the bag 21, situated beyond the nipple 88 causing damage to the 
bag 21. 
In FIG. 12 a sliding block 94 is shown, whereby in a bote 96 thereof a 
displaceable counter-matrix 97 is placed to supply counter pressure during 
welding of a flanged nipple 98 to the inner side of the bottom end 27 of 
the plastic bag 21. The nipple 98 extends into the interior through an 
opening in the bottom end 27. The bore 96 is fored as a groove so that, 
during periodic displacement, the sliding block 94 can slide with respect 
to the bag 21. 
FIG. 13 shows an electric welding schematic that a variable capacitor 102, 
a high frequency transformer 103, a first capacitor 104, a second 
capacitor plate 106, between which plates, through the plastic material of 
the bag 21, a capacitive coupling exists. The second capacitor plate 106 
lies on and contacts the sliding block 34 and is coupled by means of 
metallic conductors 107 and 108, capacitively through the material of the 
bag 21, with the die 49 for the welding on a connecting nipple. The die 49 
is connected through a metallic conductor 109 with ground 101, and also 
with the capacitor 102, thus closing the circuit. 
FIG. 14 schematically illustrates a complete machine for carrying out the 
method according to the present invention in which the various phases of 
the periodic, intermittent cycle are represented. A supply coil 36, 
disposed near the trailing end of a conveyor 111, continuously delivers a 
flat tube 22 onto the upper carrying surface 112 of an endless belt 
defining a conveyor 111. First the flat tube 22, which contains a sliding 
block 34 having a length sufficient for the simultaneous welding of a 
number of connecting nipples 28 (in the example shown, three bags), passes 
a first welding zone I, at the beginning and the end of which sliding 
rollers 37 and 38 are arranged. Rollers 37 are not shown in FIG. 14 for 
purposes of clarity but may be seen in FIG. 5. In zone I the connecting 
nipples 28 are welded into the bags 21, the long side face 41 functioning 
as a supporting face-counter electrode for welding the connecting nipples 
28 in cooperation with an outer die 49. Next, the tube 22 passes a zone II 
where, by means of a welding unit 113 composed of three parts, the welds 
are made on the edges, etc. Finally, the tube 22 passes through a zone 
III, wherein there is located the periodic driving mechanism in the form 
of clamping beams 114. In zone III there is also provided a hot punching 
device 116 for cutting and severing the individual bags from the plastic 
webs. Since therewith the integrity of the original tube is lost, the 
clamping beams 114 must be positioned before the not punching device 116. 
At the beginning of the production, when the leading end of the flat tube 
22 has been decoiled sufficiently that it arrives at the first welding 
zone I, the sliding block 34 is first inserted into the tube 22 and the 
rollers 37 and 38 or the means 39 are placed in their position s shown in 
FIGS. 5 and 14. Then the tube 22 is advanced over the stationary sliding 
block 34 until the leading end of the tube 22 enters into the welding zone 
II. There the leading end is sealed-off, permitting subsequent work to be 
carried out under entirely non-pyrogenous conditions. The tube 22 is 
advanced farther until it is engaged by the clamping beams 114. Thereafter 
the production proper starts. 
Sideways of the conveyor 111 in the welding zone I the continuous supply of 
connecting nipples takes place from a striplike narrow hose 117 which is 
wound on a supply coil 118. The hose 117 is periodically advanced by 
clamps 121 that are coupled via a transmission means (not-shown) with the 
actuation device of the clamping means 114. When the leading end of the 
hose 117 is inserted by means of the clamps 121 into the outer die 49, the 
hose 117 is cut through by means of a cutting means 122 and at the same 
time the trailing of the hose piece just cut is sealed off. Thus, a 
non-pyrogenous supply of the hose lengths is guaranteed. These two 
operations can be conducted by a combined welding-cutting device. The hose 
length thus cut is welded as a connecting nipple 28 during the stand-still 
(laydown) period of the intermittent movement of the bottom of the various 
bags 21 (for example, two nipples per bag), with the bottom of the bags 21 
facing the supporting face 41 of the sliding block 34. In this way a 
non-pyrogenous adhesion of the connecting nipples 28 to the bags 21 is 
obtained.