Note: Descriptions are shown in the official language in which they were submitted.
l 178761
-- 1 --
This invention consists of a tubular article
made of polyethylene terephthalate or a similar
material having a wall consisting of mostly amorphous
material, with a peripheral groove in the article wall
arranged in such a way that the thickness of the
material at the bottom of the groove is reduced
relative to the rest of the wall.
Canadian Patent Application No. 378,503,
filed May 28, 1981, explains how a tubular blank made
of polyethylene terephthalate or similar material can
be converted into an object consisting either in whole
or in part of monoaxially-oriented material. During
conversion, the transition zones between the amorphous
material and the oriented material are moved in the
axial direction of the blank by means of mechanical
shaping devices consisting of drawing rings that
surround
1.
1 178761 2
the blank and interact during conversion with a mandrel
inserted in the blank.
In an alternative version of the invention described in
the aforesaid Patent Application, conversion starts from
an initiating groove in the wall of the blank~ A blank
in which an initiating groove has been made will hereinaf-
ter be called an article. An article is thus an inter-
mediate product formed during conversion of the blank into
an object.
The aforesaid Patent Application states that the initiating
groove is formed by applying external pressure by means of
mechanical devices to the amorphous material in the blank
in the region where the groove is to be formed while
simultaneously applying stretching forces in the axial
direction which affect the material in this same region.
The mechanical device gradually reduces the thickness of
the material in the aforesaid region, which means that the
axial stretching force per unit of cross-sectional surface
area gradually increases in a cross-section taken through
the region where the material thickness is to be reduced.
The axial stretching forces are adapted to the properties
of the material in such a way that yield occurs in the
material a~ the bottom of the groove when the final stage
of groove formation commences. Moreover, the conversion
of the blank takes place at a temperature close to or
beneath the glass transition temperature of the blallk~
hereinafter abbreviated TG. As a rule, the temperature of
l 1787~
the blank is considerably below TG, and it should
preferably be at room temperature when the formation
of the groove commences. Obviously, the mechanical
work carried out in connection with conversion entails
an increase in the temperature of the material which,
in turn, affects the tendency of the material to yield.
A construction in accordance with the present
invention comprises a tubular article made of poly-
ethylene terephthalate or a similar material produced
from a blank having a wall of a thickness (a) consisting
essentially of amorphous material and provided with a
peripheral groove in the wall. The material in the
bottom of the groove has a thickness corresponding to
the thickness of a panel of the amorphous material
initially of thickness (a) and drawn monoaxially until
it yields at an initial temperature that is lower than
the region of the glass transition temperature (TG) of
the material.
The groove in the article comprises the initiation
region for subsequent axial orientation of the essentially
amorphous material in the article and for axial prolon-
gation of this material to form the object. The thickness
of the material at the bottom of the groove after the
groove is formed corresponds closely to the thickness
which the axially-oriented parts of the object will
acquire. One pre-requisite for providing this material
wall thickness when the article is converted to an
object is thus that the initial positions of the drawing
rings are such that when they are moved in the article's
1 178761 3A
axial direction, they will provide the necessary
material reduction and thus the correct object
material thickness. In a preferred version of
this invention, this is achieved by having the inside
of the bottom of the groove largely flush with the
inside of the adjacent amorphous material, thus making
certain that it will be possible for the drawing rings
to assume the aforesaid initial positions.
I 1 7876 1 4
In an alternat ve version of this invention, the final
forming of the groove is accomplished by having the draw-
ing rings, when being placed in the initial positions,
provide the movement of material in the bottom of the groove
towards the object's axls that is required to achieve .
the position of the material wall set forth in the previous
paragraph.
Application of this invention provides an article with a
peripheral groove arranged in such a way that the thick-
ness of the material in the bottom of the groove is re-
duced relative to the thickness of the adjacent walls.
The wall thickness in the bottom of the groove shall
thus correspond to the thickness a sheet or panel, made
of the same amorphous material as that adjacent to the
groove and having a thickness corresponding to the
thickness of the material of the article adjacent to the
groove, obtains when having a temperature corresponding to
the temperature which the material at the bottom of the
groove has immediately before the final phase of formulation
of the groove and the sheet or the panel drawn monoaxially
until it yields. The material in the wall at the bottom
of the groove has a crystallization in the range 10-30 %,
preferably in the range 10-17 %.
An article having a region of material at the bottom of
the groove with an orientation and, sometimes, a supple-
mentary thermal crystallization that causes overall
ll78~61 5
crystallization to the extent mentioned in the previous
paragraph is well suited for conversion to an object. As
reduction of the wall thickness of the parts of the ar-
ticle adjacent to the groove continues due to the fact
that its material is caused to yield, one obtains a region
of reduced material thickness consisting of the initial
region formed by the bottom of the groove and the adjacent
areas having reduced material thickness. The material
region thus provided forms, sometimes after supplementary
thermal crystallization, an essentially uniform material
region both mechanically and thermally. In cor.nection with
the production of a bottle, for example, one can permit
this material region to form the neck and mouth of the
bottle, thus making it possible to provide a bottle
having considerably better characteristics with regard
to strength and temperature resistance. Moreover, the
material thickness in the neck and mouth of the bottle
is reduced relative to what is possible with the methods
and devices heretofore known.
One special advantage of the groove is that it makes it
possible to provide regions of reduced-thickness material
arranged symmetrically around the groove. This is impor-
tant because it permits the article to be used in appli-
cations calling for two containers such as bottles ar-
ranged opposite each other and produced in one or more
operations.
In one version of this invention, successive reduction of
i 178761 6
the material thickness is accomplished by a number of
rollers, although only one roller is used in certain
applications. When the groove is formed, the roller or
rollers are moved around the periphery of the blank while
S the distance to the blank axis is gradually reduced and
while the material which contacts the roller or rollers
is exposed to the aforesaid stretching forces.
In a preferred version of this invention, three rollers
are used, and they are brought into contact with the wall
of the blank successively and are then moved gradually
towards the axis of the blank as the groove is formed.
The roller which first contacts the wall of the blank and
commences to form the groove has a relatively narrow con-
tact surface. It is followed by the second roller which
further deepens and widens the groove while simulta-
neously reducing the thickness of the material in the
bottom of the groove to a value which permits the stretch-
ing forces per unit of area to accomplish the aforesaid yield
of the material. This provides relatively symmetrical
streching of the material while it is simultaneously
being thinned, and as a result the inner surface of the
material wall at the bottom of the groove is moved
slightly away from the axis of the blank. The third
roller serves as a shaping roller which moves the ma-
terial wall to a position at which its inner surface is
largely flush with the inner surfaces of the adjacent
parts of the material.
l 178761 7
In an alternative version of this invention, the rollers
are replaced by an extended shaping device having an edge
against which the blank rolls while the distance of the
edge from the axis of the blank is reduced. Preferably, the
device terminates in a part having an edge with a width, a length
and a position which, because of the movement relative to the
blank will affect the material in the bottom of the groove
in roughly the same way as set forth for the third roller
mentioned in the previous paragraph. The extended shaping
device shall preferably be roughly circular and designed
in such a way that the shaping edge is on the inside of
the ring. This simplifies control, guidance and movement
of the blank and also simplifies its movements relative
to the shaping device.
During formation of the groove,
a central mandrel is usually provided inside the '
~lank. The mandrel has a central part which serves as a
support for the wall of the blank in the region where the
groove is to be formed. At the two ends of the blank, the
mandrel is also provided with sections which also serve
as supports for the wall of the blank in order to prevent
the ~lank from being deformed by the fixing devices which
grip the blank in connection with the application of the
aforesaid stretching forces used to form the groove.
Fixing devices are also needed to provide reliable guid-
ance of the blank relative to the shaping device or de-
vices while the groove is being formed.
1178761 8
This invention is intended especially for use in connec-
tion with the production of articles made of thermoplastic
of the polyester or polyamide type. One example of such a
material is polyethylene terephthalate. Other examples are
polyhexamethylene-adipamide, polycaprolactam, polyhexa-
methylene-sebacamide~ polyethylene-2.6- and
1,5-naphthalate, polytetramethylene-1,2-dioxy-
: benzoate and copolymers of ethylene terephthlate, ethy-
lene isophthalate and other similar polymer plastics.
The description of this invention is related, for the most
part, to polyethylene terephthalate, hereinafter often
abbreviated to PET. However, this invention is not limited
to the use of this material or any other of the previously
mentioned materials. It is applicable for many other
thermoplastic materials as well.
The crystallization percentages mentioned previously in
connection with PET and which will be mentioned again in
connection with PET, are related to the theory set forth
in the publication entitled "Die Makromolekulare Chemie"
176, 2459-2465 (1975).
This invention is described in greater detail in connec-
tion with the following illustrations:
Fig. 1 a-d illustrates the general cycle used to form
an article from a tubular blan~.
I 1 7876 1 9
Fig. 2 a, b illustrates in detail the final formulation
of the groove in the article.
Fig. 3 presents a perspective view of one version
of the invention.
Fig. 4 presents a perspective view of an alternative
: version of the invention.
Fig. 5a, b presents a cross section and axial section
showing details of the version of the inven-
tion shown in Fig. 3, particularly the ar-
rangement of the shaping rollers.
Fig. 6 presents an axial section showing details
of a fixing device and drawing device used
in either of the versions of this invention
shown in Fig. 3 and Fig. 4.
15 Fig. 1 a-d illustrates the principles of this invention
as follows. A blank 10 consisting ~ssentially of amorphous
material is provided with a peripheral groove 12 through-
out a shaping cycle, sometimes called a conversion cycle,
in which a number of shaping rollers 31-33 are success-
ively brought to bear against the blank and simultaneous-
ly moved peripherally around the blank and also towards
the blank axis. Reference number 17 indicates a blank in
which the formation of the groove has commenced. Reference
number 18 indicates a blank in which the material in the
7~
bottom of the groove has yielded. Reference number 19
indicates an article made from blank 10 in which groove
12 has obtained its final form. The letter b at lower
right in Fig. ld indicates half of the prolongation of
the blank which occurs during conversion to article 19.
A mandrel 20 is provided inside the blank, and it has a
: central part 22 and outer parts 21 a, 21 b. The mandrel
also has an axis 23 along which the outer parts of the
mandrel can be moved. Springs (not shown in the illustra-
tions) tend to keep the outer parts of the mandrel 21 at
the positions shown in Fig. 1 a. Moreover, fixing ~evices
34 a, 34 b are arranged to hold the outer parts of the
blank by clamping them between the fixing device and the
outer parts of the mandrel 21 a, 21 b. The fixing devices
are also arranged so that they can be moved in the axial
direction of the blank while simultaneously holding the
blank securely by means of the aforesaid clamping arrange-
ment. This movement is indicated by arrow H which also in-
dicates the directions of the axial stretching forces
which are applied to the material via the fixing devices.
In connection with the application of this invention,
blank 10 i5 threaded over the mandrel until it strikes a
stopping surface 35 on fixing device 34 a. This provides
accurate axial positioning of the blank on the mandrel.
The fixing devices grip the ends of the blank, after
which the fixing devices are asted on by a driving device
to provide stretching forces in the axial direction.
~ 178761 ll
Rollers 31-33 are then brought to bear successively on the
wall of the blank, and they are moved around the blank's
periphery while simultaneously being moved gradually to-
wards the blank axis. Roller 31, which contacts the wall
of the blank first and commences to form the groove has
a relatively narrow contact surface. It is followed by
roller 32, which is brought into contact with the material
in such a way as to widen and deepen the shallow groove
formed by the first roller. The second roller deepens
the groove while simultaneously reducing the thickness
of the material in the bottom of the groove to a value
which permits the stretching forces applied to the ma-
terial 15 in the bottom of the groove to cause the ma-
terial to yield. The material is thus thinned, while its
inner surface simultaneously moves slightly away from
the central part of the mandrel 22. The third roller 33
which has a shape adap~ed to the desired final shape of
the groove that is intended to be formed then moves the material
15 in the bottom of the groove into contact with the
central part of the mandrel 22, whereupon the inner sur-
face of material 15 in the bottom of the groove assumes
a position that is largely flush with the adjacent inner
surfaces of the article that is formed 19. When the forming
of the groove commences, the material is at a temperature
which is considerably below its glass transition tempera-
ture (TG).
Fig. 2 a, b presents an enlarged, detailed illustration
of the final phase of the forming of the groove. In addi-
1 178761 12
tion to the reference numbers and letters used in Fig. 1a-d, the original thickness of the material wall is indi-
cated by the letter a, and the thickness of the material
in the bottom of the groove is indicated by the letter d.
Fig. 3 presents one version of a device used to apply
this invention in which shaping rollers are used as shap-
: ing devices. A frame 40 is arranged with a central drive
shaft 41 on which are attached a number of holders 43 a-d.
A stepping motor 42 serv~s as the driving device for the
central drive shaft and moves the conversion stations to
the positions marked I-IV in the illustration. The holders
support the devices which form the conversion stations in
which the blank is converted to an article. In this illus-
tration, and also in Fig. 4, the devices used in the con-
version stations are indicated by reference numbers to
which the letters a, b, c and d have been appended to
indicate that the device in question belongs to a parti-
cular conversion station.
~ supporting shaft 44 is attached to each holder and
supports a first fixing device 67 which, at positions I
and IV, is moved by driving device 72 out to the exposed
end of supporting shaft 44. Another driving device 74 is
connected via lever 78 to this first fixing device 67 in
order to secure one end of the blank 10 that is to be
converted into article 19. A second fixing device is
contained in holder 43. Another driving device 75 is
connected via a lever 79 to secure the other end of the
1 178761 13
blank. A first and second pressure sleeve 97, 98 are
provided between the two fixing devices in such a way
that they straddle a sleeve 56 which contains shaping
rollers 31-33. The illustration also shows driving device
46 which, via levers 47, provides the aforesaid movement
of the shaping rollers perpendicular to the axis of the
blank. Driving device 76, via a link system and eccentrics
95, moves pressure sleeves 97, 98 in the axial direction
of the blank. Each conversion station is also provided
with its own driving device 45 which rotates mandrel 20
and thus the blank which is secured to the mandrel by
means of fixing devices 67, 68.
Fig. 3 also shows a feed device for blanks 10. This device
feeds the blanks into the first fixing device 67 when the
conversion station is at position I. Feed wheels 65, in
combination with blank carrier 64 and a feed/discharge
device 66 are all a part of the feed device.
Fig. 4 shows an alternative version of a device used for
the application of this invention in which the shaping
rollers are replaced by an extended shaping device 60 with
an edge 61. This edge forms a roughly circular limiting
surface which has a varying width and varying distance
fro~ the centre of rotation. A part of the limiting sur-
face must have a length corresponding to at least the
circumferance of the blank. Moreover, this part of the
limiting surface must have a shape which corresponds to
the shape which the groove is to have when conversion into
1 1787~b~ 14
an article is completed.
Shaping device 60 is arranged as a roughly circular hol-
der 59. The driving device (not shown in the illustration)
can rotate the shaping device around its axis.
Frame 63 is arranged on base 62. The frame has a centrally
located hole 58. Feed wheels 65, blank carrier 64 and
feed/discharge device 66 are arranged relative to the hole
in accordance with the description of Fig. 3.
A number of supporting arms 69 (four in this illustration)
are arranged relative to frame 33 and on sliding shafts 70
by means of a bearing 71 in such a way that the supporting
arms can be moved from one position adjacent to frame 63
to another position close to shaping device 60 and back
again to the first position. At the other end, each sup-
porting arm is provided with a first fixing device 67
which corresponds to the first fixing device mentioned
in the description of Fig. 3. Sliding shaft 70 is also
carried on bearing 77 in frame 63 so that, by means of
driving device 73, it can be turned between one position
in which the first fixing device 67 is located at the
centre of hole 58 and a second position that corresponds
approximately to the position of edge 61 on shaping device 60.
Supporting devices 69 are attached to the frame 63. Devices 69
have each a first fixing device 67, which interacts with a second
l1~876~ 15
fixing device 68 arranged adjacent to two pressure
sleeves 98, 97. The second fixing device and the press-
ure sleeves, together with the first fixing device form
a conversion station for blank lO when the first fixing
device 67 is moved to a position adjacent to shaping de-
vice 60. Driving devices 74-76 with their link system are
provided for fixing devices 67, 68 and for pressure
sleeves 97, 98 in the same way as shown in Fig. 3. The
reference numbers for these link systems are the same as
the reference numbers used in Fig. 3. Reference number 78
indicates a lever for the first fixing device 67. Refer-
ence number 79 indicates a lever for the second fixing
device 68.
In Fig. 5 a, b, Fig. 5 b shows section 5b-5b in Fig. 5 a,
i.e. a section taken along blank lO's axis in a device
like the one shown in Fig. 4. Fig. 5 a, b illustrates the
structure of a shaping device that consists of shaping
rollers. Circular housing 50 contains supporting device
48 on which lever 47 is attached. The supporting device
can rotate in housing 50. A number of guide rollers 49 are
carried on supporting device 48 and follow it when it
moves. Shaping rollers 31-33 are carried in roller holder
51. The roller holder has a guide surface 52 against which
each of guide rollers 49 roll. The roller holders can
rotate around pivot point 53. A spring 54 returns the
roller holders to their initial positions so that blank lO
can be fed in between the rollers. Roller holders 51 are
mounted on a ring 55 which is attached to circular housing 50.
l 178761 16
Fig. 6 presents a section taken in the axial direction
of blank lO through the part of the conversion station
which secures one of the ends of the blank. In this -
illustration, the blank has been threaded onto the mandrel.
Reference number 25 indicates an extension of the mandrel
axis 23. This extension is carried in bearing 99. In a
version of this invention in which shaping rollers are
used, extension 99 is connected to driving device 45,
while in an alternative version where shaping is carried
out by means of an extended shaping device, the mandrel
runs freely in bearing 99. Reference number 81 indicates
a fixed sleeve in which bearing 99 and the other devices
located adjacent to the fixing devices and stretching
devices used for blank lO are mounted.
The aforesaid lever 79, is attached to transmission device
82. When the lever moves, transmission device 82 is
screwed into threaded member 83 and simultaneously pulls
tapered device 94 in and over fixing jaws 85. As a result,
the blank is securely clamped between the fixing jaws and
the outer part of mandrel 21. The fixing jaws are arranged
in a holder 38. Bearings 87, 84 permit holder 38 and the
tapered device 94 to rotate when b]ank 10 rotates.
The aforesaid lever 88 is attached to actuator 89 which,
when the lever moves, is screwed out of holder 90 and
moves a pressure sleeve 91 against part 83 which, in turn,
moves into the fixed sleeve. This exerts a pulling force
1 178761 17
on blank 10 via fixing jaws 85~ Part 83 is prevented from
rotating by stop pin 93.
When a blank 10 is converted into an article 19 by means
of the version of the invention shown in Fig. 3, blank 10
is fed by means of feed wheels 65, blank carrier 64 and
feed/discharge device 66, whereupon the feeding operation
is terminated by a shoulder in the first fixing device
67 a. Driving device 74 actuates the fixing device so that
the blank is secured firmly by the first fixing device.
Simultaneously, the first fixing device is actuated by
driving device 72 a in such a way that it moves into con-
tact with the first pressure sleeve 97. Also simultaneous-
ly, the blank is inserted between shaping rollers 31-33
(see Fig. 5 a, b). Also simultaneously, the other end of
the blank is moved against stopping surface 35 in the
second fixing device 68 a (hidden in the illustration).
Driving device 75 then actuates the second fixing device
so that it secures the other end of the blank.
When driving device 46 a, which provides movement of the
shaping rollers towards the axis of the blanks is actuated,
the shaping rollers are moved as described above in
connection with Fig. 5 a, b in order to form groove 12.
Driving device 76 a, when i~ is actuated, exposes the ma-
terial to stretching forces in the same way as described
previously. Then, when the thickness of the material in
the bottom of the groove reaches a predetermined value,
it will yield. As a result, the blank is stretched. Con-
1 1787~ 18
version to an article is then concluded when shaping
roller 33 moves the material in the bottom of the groove
into contact with the mandrel thus determining the final
shape of the groove. Relative movement between the shaping
rollers on the one hand and the blank on the other is
provided by driving device 45 a, after the two ends of the
blank have been secured in the first and second fixing de-
vices by that the driving device 45 a rotates the mandrel
and thus rotates the blank itself.
While the cycle described above is being carried out,
stepping motor 42 moves the conversion station step by
step from position I to position IV, as shown in the il-
lustration.
At position IV, the shaping rollers are returned to their
initial positions, and the second fixing device releases
the blank. Thereafter, driving device 72 a moves the first
fixing device 67 a back to its initial position. Driving
device 74 a returns to its initial position and releases
the end of the article, after which a new blank 10 can be
moved in the axial direction into the first fixing device
while article 19 a is simultaneously discharged.
The above paragraphs have explained how a conversion sta-
tion is used to convert a blank to an article. Each of the
conversion stations converts one blank in the same manner
as set forth above. Even though the illustration shows
four conversion stations, it is posslble to arrange a de-
l 17876~ 19
vice like the one shown in Fig. 3 with more or fewer con-
version stations.
Moreover, the description refers to the use of three
shaping rollers which successively shape the groove. De-
pending upon the way in which, for example, the width and
shape of the groove are to be formed, it is possible
: within the scope of this invention to use either more or
fewer shaping rollers.
When converting a blank 10 into an article 19 using the
version of this invention shown in Fig. 4, blank 10 is
fed in the same way as described in connection with Fig.
3, after which the first fixing device 67 a is moved by
driving device 73 a to the position shown by the broken
lines in Fig. 3. Driving device 72 a then moves the fixing
device to a position adjacent to the extended shaping de-
vice 60 where, together with the second fixing device 68 a
and the intermediate devices such as actuator 89 and hol-
der 90, it forms the composite device used to secure the
blank while it is being converted to an article.
Now, the other end of the blank is secured in the same
way as described in connection with Fig. 6, whereupon the
material in the region where the groove is to be formed
is exposed to axial stretching forces.
The driving devices rotate the extended shaping device 60
which, when the blank was moved to the aforesaid position
1 17~7~1 2~
assumed a position at which edge 61 did not obstruct axial
movement of the blank. As rotation proceeds, edge 61 is
gradually moved closer to the centre of the blank, where-
with the blank rolls against the edge while the groove is
being formed. In the same way as described previously,
the material at the bottom of the groove yields after a
certain time interval. The final shape of the groove is
then determined by having the material in the bottom of
the groove contact an edge shaped and located in such a
way that the material wall is pressed against the central
part of the mandrel throughout at least one full revolu-
tion of the blank. This procedure provides the final shape
of the groove.
As the rotation of the extended shaping device continues,
edge 61 moves away from the material in the newly-formed
article, and the second fixing device releases the ar-
ticle, after which the first fixing device is moved to
its initial position. The article is then released and a
new blank is moved axially into the first fixing device
while the article that was formed is simultaneously dis-
charged.
In this version of the invention, it is also possible to
provide more or fewer conversion stations than shown in
the illustration.
The material in the bottom of the groove becomes crystal-
lized to a maximum of approximately 17~, which through
l 1 787~ 1 21
supplementary thermal crystallization can provide a maxi-
mum of approximately 30% without causing problems when the
article is subsequently shaped into new products.
This invention is intended especially for application in
connection with the production of articles made of thermo-
plastic of the polyester or polyamide types. Examples of
such materials were presented in the introductory part of
this description.
In addition to the above specification, the invention is
also described in the following Patent Claims.
This application is a division of application Serial
No. 378,540 filed May 28, 1981.
1981-05-15
MG/Fgi
