U.S. patent number RE29,446 [Application Number 05/706,672] was granted by the patent office on 1977-10-18 for apparatus for shaping the end of a tube.
This patent grant is currently assigned to Thyssen Plastik Anger. Invention is credited to Johann Gutlhuber, Max Sonnleitner, Karl Hermann Wolf.
United States Patent |
RE29,446 |
Sonnleitner , et
al. |
October 18, 1977 |
**Please see images for:
( Certificate of Correction ) ** |
Apparatus for shaping the end of a tube
Abstract
.Iadd.Apparatus to produce widenings at tube ends with precise
dimension of the inner surfaces of the widened zone which includes
a holding device for the tube to be worked, a variable form core
arranged axially in front of the center of the holding device, a
device for axially displacement of the core, a cylinder axially
movable over the tube for exterior calibration and adaptation of
the tube end to the core, and a device to bring the core to a shape
in which it can be drawn from the formed tube end. .Iaddend.
Inventors: |
Sonnleitner; Max (Oberaltaich,
near Bogen, DT), Wolf; Karl Hermann (Bogen,
DT), Gutlhuber; Johann (Irlbach, near Straubing,
DT) |
Assignee: |
Thyssen Plastik Anger
(DT)
|
Family
ID: |
27512134 |
Appl.
No.: |
05/706,672 |
Filed: |
July 19, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
176179 |
Feb 23, 1962 |
03205535 |
Sep 14, 1965 |
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Foreign Application Priority Data
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Nov 22, 1961 [DT] |
|
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K 45267 |
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Current U.S.
Class: |
425/297;
425/DIG.218; 425/325; 425/379.1; 425/403; 425/378.1; 425/393 |
Current CPC
Class: |
B29C
57/04 (20130101); B29C 67/0003 (20130101); B29C
67/0014 (20130101); B29D 23/18 (20130101); B29L
2023/003 (20130101); B29C 48/09 (20190201); B29C
48/13 (20190201); B29C 2948/92438 (20190201); B29C
2948/926 (20190201); B29C 2948/92647 (20190201) |
Current International
Class: |
B29D
23/18 (20060101); B29C 57/00 (20060101); B29C
57/04 (20060101); B29C 67/00 (20060101); B29C
017/14 () |
Field of
Search: |
;425/297,378R,379R,392,393,DIG.218 ;72/58,59,370 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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563,423 |
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May 1957 |
|
IT |
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798,692 |
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Jul 1958 |
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UK |
|
Primary Examiner: Shore; Ronald J.
Attorney, Agent or Firm: Kane, Dalsimer, Kane, Sullivan and
Kurucz
Claims
What is claimed is:
1. Apparatus for processing a settable material comprising
extrusion means including a core for extruding material to the form
of a hollow tube; means for urging said material through said
extrusion means at a determinable speed; treating means adjacent
said extrusion means to cause material emerging from the latter to
set at least in part; drawing means to engage the material treated
by said treating means and to convey the material away from said
extrusion means at a speed having a determinable relationship to
said determinable speed; control means to regularly and
periodically vary said relationship whereby an accumulation of said
material is effected in successive portions of the extruded hollow
tube, said extrusion means comprising means engaging the hollow
tube thus formed along the outer surface thereof to form the tube
with a constant outer diameter such that the accumulation of
material is formed along the inner surface of the tube at regular
intervals along said tubes; means for severing the tube at the
locations therein whereat there is an accumulation of material to
thereby form a plurality of tubular units having a uniform outer
diameter and at least one end with an increased thickness; means
for receiving the units one by one; and means related to the
extrusion means for deforming the units at the ends of increased
thickness in relation to the magnitude of said increased thickness
to produce units each with widened ends having substantially the
same thickness and the remainder of the unit, said means for
deforming the units comprising a plurality of angular spaced first
core sections distributed about a determinable axis, means
supporting said sections for movement in respective radial planes
related to said axis, said core sections being of wedge-shaped
cross-section, a plurality of second core sections distributed
about said axis, means supporting the second core sections for
movement in radial planes related to said axis, said second core
sections being positioned for interdigitation with the first core
sections to constitute a core, means for radially displacing the
second core sections into and out of positions for engaging with
the first core sections, and means to move the core sections
relatively along said axis into and out of engagement with each
other.
2. Apparatus for shaping the end of a tube comprising a plurality
of angularly spaced first core sections, distributed about a
determinable axis, means supporting said sections for movement in
respective radial planes related to said axis, said core sections
being of wedge-shaped cross-section, a plurality of second core
sections distributed about said axis, means supporting the second
core sections for movement in radial planes related to said axis,
said second core sections being positioned for interdigitation with
the first core sections to constitute a core, means for radially
displacing the second core sections into and out of positions for
engaging with the first core sections, and means to move the core
sections relatively along said axis into and out of engagement with
each other.
3. Apparatus for shaping the end of a tube comprising a plurality
of angularly spaced first core sections distributed about a
determinable axis, means pivotally supporting said sections for
movement in respective radial planes related to said axis, said
first core sections being of wedge-shaped cross-section, a
plurality of second core sections, means pivotally supporting the
latter for movement in radial planes related to said axis, said
second core sections having a quadrilateral cross-section and being
positioned for interdigitation with the first core sections to
constitute a core, means for pivoting the second core sections into
and out of positions for engaging the first core sections, further
means to move the second core sections into and out of engagement
with the first core sections, means for encircling said core and
forming a die therewith, means for engaging said tube and
positioning the same for engagement by said die, means operatively
positioned to heat said tube prior to the engagement thereof, and
means to cool the tube after the deforming thereof.
4. Apparatus for shaping the end of a tube comprising a first
member constituting a guide for said tube, a device defining an
axis and axially displaceable toward and away from said first
member, a group of angularly spaced first core sections circularly
distributed about said axis and pivoted to said first member for
movement in respective radial planes related to said axis, said
core sections constituting part of a core adapted for shaping said
tube, a second member axially displaceable with respect to said
device, a group of second core sections pivoted on said second
member for movement in radial planes related to said axis, said
second core sections being positioned for interdigitation with the
latter to complete said core, means on said device for engaging the
second core sections and pivoting the same into and out of
positions for engaging with the first core sections, and means to
move the first and second core sections into and out of engagement,
said groups of sections respectively having wedge-shaped and
substantially rectangular cross-sections in a determinable plane
perpendicular to said axis.
5. Apparatus comprising a rod, a first member fixed on said rod and
constituting a guide for a tube, a device axially displaceable on
said rod toward and away from said first member, a bar connected to
said device whereby the latter may be controlled, a plurality of
spaced first core sections peripherally distributed about said rod
and pivoted to said first member for movement in respective radial
planes related to said rod, said first core sections being of
wedge-shaped cross-section, a second member axially displaceable on
said device, a plurality of second core sections pivoted on said
second member for movement in radial planes related to said rod,
said second core sections being of rectangular cross-section and
being positioned for interdigitation with the first core sections
to constitute a core, means for engaging the second core sections
and pivoting the same into and out of positions for engaging with
the first core sections, and means on said device to engage the
second core sections upon movement of said device axially with
respect to said rod to move the second core sections into and out
of engagement with the first core sections.
6. Apparatus comprising an elongated rod having a slot therein, a
member fixed on an end of said rod and adapted for constituting a
guide for a tube, a cylinder axially displaceable on said rod
toward and away from said member, a bar axially displaceable within
said rod, a pin extending through said slot and connecting said bar
and cylinder whereby the latter may be controlled, a plurality of
spaced first core sections peripherally distributed about said rod
and pivoted to said member for movement in respective radial planes
related to said rod, said core sections having outer surfaces
adapted to deform said tube and being of wedge-shaped cross-section
adjacent said surfaces, a second member axially displaceable on
said cylinder, a plurality of second core sections pivoted on said
second member for movement in radial planes related to said rod,
said second core sections including outer surfaces corresponding to
the first said surfaces and being positioned for interdigitation
with the first core sections to constitute a core, means on said
cylinder for engaging the second core sections and pivoting the
same into and out of positions for engaging with the first core
sections, and further means on said cylinder to engage the second
core sections upon movement of said cylinder axially with respect
to said rod to move the second core sections into and out of
engagement with the first core sections.
7. Apparatus for forming the end of a tube comprising an elongated
rod having a diametral slot therein, a first annular member fixed
on an end of said rod and constituting a guide for said tube, a
cylinder axially displaceable on said rod into and away from
abutting relationship with said annular member, a bar axially
displaceable within said rod, a pin extending through said slot and
connecting said bar and cylinder whereby the latter may be
controlled, a plurality of angularly spaced first core sections
peripherally distributed about said rod and pivoted to said annular
member for movement in respective radial planes related to said
rod, said core sections including bulbous outer portions adapted to
deform said tube and being of wedge-shaped cross-section adjacent
said portions, a second annular member axially displaceable on said
cylinder, a plurality of second core sections pivoted on said
second annular member for movement in radial planes related to said
rod, said second core sections, including bulbous outer portions
corresponding to the first said bulbous portions and being
positioned for interdigitation with the latter to constitute a
core, means on said cylinder for engaging the second core sections
and pivoting the same into and out of positions for engaging with
the first core sections, further means on said cylinder to engage
the second core sections upon movement of said cylinder axially
with respect to said rod to move the second core sections into and
out of engagement with the first core sections, and means for
encircling said core and forming a die therewith.
8. Apparatus for deforming the end of a tube comprising an
elongated rod having a diametral slot therein, a first annular
member fixed on an end of said rod and constituting a guide for
said tube, a cylinder axially displaceable on said rod into and
away from abutting relationship with said annular member, a bar
axially displaceable within said rod, a pin extending through said
slot and connecting said bar and cylinder whereby the latter may be
controlled, a plurality of angularly spaced first core sections
peripherally distributed about said rod and pivoted to said annular
member for movement in respective radial planes related to said
rod, said core sections including bulbous outer portions adapted to
deform said tube and being of wedge-shaped cross-section adjacent
said portions, a second annular member axially displaceable on said
cylinder, a plurality of second core sections pivoted in said
second annular member for movement in radial planes related to said
rod, said second core sections including bulbous outer portions
corresponding to the first said bulbous portions and being
positioned for interdigitation with the latter to constitute a
core, means on said cylinder for engaging the second core sections
and pivoting the same into and out of positions for engaging with
the first core sections, further means on said cylinder to engage
the second core sections upon movement of said cylinder axially
with respect to said rod to move the second core sections into and
out of engagement with the first core sections, means for
encircling said core and forming a die therewith, means for
engaging said tube and positioning the same for engagement by said
die, means operatively positioned to heat said tube prior to the
engagement thereof, and means to cool the tube after the deforming
thereof.
Description
This invention relates to the production of extruded tubes, with
widenings and/or thickenings extending transversely to the
direction of discharge of extruded material from the associated
extruder. The invention also relates to the finishing of said
extruded tubes.
Difficulties arise when connecting tubes, particularly synthetic
plastic tubes, because as a rule one end of each tube fitting must
be widened or, for example, if a thread has to be made in it, a
thickening of the end is necessary. If in the first case the tube
is widened out from its normal diameter to the increased diameter
of a socket for the next tube, and annular corrugations are
furthermore provided in the widened portion to accommodate sealing
rings, then the widened portions have a smaller wall thickness than
tube portions of normal diameter. This is most advantageous, as the
portions with the larger diameter of course require an increased
wall thickness if they are to be subjected to the same pressure as
the unwidened portion of the tube. Attempts have been made to
overcome these difficulties by shrinking an annular tube, before
the widening, over the corresponding tube end in the manner which
is usual in armament production. Such a solution is however very
unsatisfactory, as it is expensive and time-consuming in production
and furthermore very accurate calculation is required if the
stresses arising on the inner and outer tubes are to be uniformly
distributed. As a rule, however, tolerances on synthetic plastic
tubes are so large that the calculated value can certainly not be
maintained.
Attempts have also been made to avoid the difficulty by accepting
the thinner wall thickness at the sleeve ends of the tube and
reducing the maximum pressure accordingly. This procedure, however,
results in a considerable expenditure of material, as the total
length of the tube, which is normally five meters or more, is
overdimensioned.
The defects of the hitherto conventionally extruded tubes, are
obviated in accordance with the invention in an extremely simple
and efficient manner, in that the tube string emerging from the
extruder is upset at the desired distances while still in the
deformable condition, in lengths corresponding to the widenings or
thickening, to form a greater wall thickness, and that if required
the widening and/or further treatment of the thickening is effected
as will be hereinafter described. This enables the existing
difficulties to be overcome almost without any additional
expenditure, as the upsetting can be effected very simply.
With thermoplastic material the thickening of the tube wall is
advantageously effected before the end of complete
polymerization.
In extruding tubes the tube string emerging from the extruder is
advantageously guided by a cooled calibrating collar, in which the
tube string is substantially finally polymerized. In the present
invention the upsetting is advantageously effected in this collar.
In this case the thickening obtained is on the inside. It may be
produced, for example, by the extruder being temporarily stopped
and the finished tube string being moved back one piece in the
meanwhile. The upsetting can also be effected by the tube string
being drawn off by a draw-off device following the extruder, at
constant speed, and, for a short time during the emergence of the
corresponding string portion from the extruder, the output of the
latter being increased. The upsetting is, however, particularly
advantageously effected by a periodic reduction of the speed of the
draw-off device following the extruder, for the finished tube
string.
If the thickening of the hollow tube string is provided outwardly,
then this is advantageously upset over a calibrating mandrel and
fully polymerized.
During the upsetting in a calibrating collar, an overpressure,
produced for example by compressed air being fed thereto, is
advantageously maintained inside the tube string, which presses the
tube against the calibrating collar. A special device for this is
not necessary, because as a rule, the production of a smooth tube
string is effected with an interior overpressure prevailing at
least in the zone of the calibrating collar.
After the upsetting, the finished tube string can be divided in the
vicinity of the thickenings, after which these are widened in known
manner to the desired diameter and desired sectional profile.
The process according to which the apparatus invention is utilized
is advantageously effected by means of a known device, which
comprises in sequence an extruder, possibly a calibrating device,
preferably a cooling device such as a water-bath connected thereto,
and finally a draw-off device. This draw-off device is provided in
accordance with the invention with an automatically acting device
which periodically reduces the draw-off speed at the desired
distances so that in the calibrating device during the period of
reduced speed, a thickening of the tube string takes place. Said
automatically acting device may be a mechanical one, as it is e.g.
provided with automatic lathes, particularly multi spindle
automatics, or an electrical control circuit. Such devices are
known to one skilled in the art. They are described for example in
"Dubbels Taschenbuch fiir den Maschinebau," vol. 2, page 627
(edited by Dr. ing. F. Sass and Dipl. Ing. Ch. Bouche, Springer
Verlag, Berlin, Gottingen and Heidelberg, 1958). The reduction of
the draw-off speed may also be manually controlled; however, an
automatic control device is preferable.
The calibrating device may advantageously be a water-cooled collar
surrounding the tube string emerging from the extruder.
Advantageously, a pipe for a pressure gas, preferably air, is
provided, through which an overpressure is provided inside the
portion of the tube string located within the collar, pressing this
against the collar.
In the case of synthetic plastic tubes, increases in the internal
diameter are also necessary when the tubes are to be joined
together by means of spigot and socket arrangements, in which case
one tube end is widened out to form a socket in which the unwidened
end of another tube is inserted. The socket must then be provided
with a corrugation which accommodates a sealing ring.
In this case the widenings have hitherto been produced by
introducing the temporarily softened tube end into an outer female
die determining the external form of the widening and a pressure
medium, air for example, being introduced into the tube end, by
which pressure medium the softened tube wall is flexibly adapted to
the inner surface of the die. Certainly in this way the outer form
is very accurately determined, but not the inner form, which
depends on the plastic flow behavior of the tube material. However,
it is important to maintain accurately the inner shape of the
widenings, as the sealing of the male tube end in the socket
depends decisively on the socket diameter and corrugation diameter
and shape being accurately maintained. Furthermore, it is essential
that the wall thickness of the corrugation in the tube does not
decrease too much in relation to the other tube wall thickness.
One object of the invention is therefore to make it possible to
produce widenings, of the kind mentioned above, at tube ends with
the utmost precision of dimension of the inner surfaces of the
widened zone, particularly in connection with the aforesaid tube
connections. This and other problems are solved by the tube end
being drawn in plastic condition on a core which is variable in
form and has the desired internal form of the widenings, the tube
end being fixed over this, after which the core is removed from the
tube end, a deformation of the core taking place, in particular a
collapsing. Obviously, in accordance with the principle of
relativity in mechanics, the core may just as well be inserted in
the tube end, or both parts can be simultaneously moved one upon
the other. Corresponding tests have shown that it is surprisingly
possible to push the tube end, rendered plastic, over the widened
core, substantially without any jamming, while the tube end again
tapers behind the portion of the core again tapering towards the
tube end. There is substantially no upsetting of the plastic tube
end. The very slight upsetting, which may occur under certain
circumstances, may even be desirable, as by this the thinning of
the wall, which occurs as the diameter of the tube end increases,
is partially or wholly compensated.
The invention is advantageously carried out in such a way that the
widening zones of the tube tapering towards the tube end, are
flexibly adapted to the core and/or are calibrated by means of an
outwardly engaging device. In this way it is further possible to
make any desired correction to the wall thickness. Furthermore, the
end face of the tube can be conjointly formed, so that it lies
accurately in a plane normal to the axis of the tube. It may be
given any desired profile and, for example, may be rounded.
The tube end is advantageously pushed onto the core with the use of
a lubricant such as, preferably, oil.
The core is advantageously heated before the tube end is pushed on,
in order to prevent any premature solidification of the tube
end.
The invention makes it possible to produce connecting sockets for
tube ends with a degree of accuracy in measurement and shape not
hitherto known.
The invention also contemplates the provision of a device for
carrying out the widening operation. The device is characterized by
the inclusion of a holding device for the tube to be worked, a
variable-form core arranged axially in front of the center of this
holding device, a device for axial displacement of the core and
also a device to bring the core to a shape in which it can be drawn
from the formed tube end.
There is advantageously provided, for exterior calibration and/or
flexible adaptation of the tube end to the core, a cylinder which
is axially movable over the tube end and is given a profile
corresponding to it.
Advantageously hydraulic moving devices are provided for the tube
holding device, the profiled cylinder and the deforming of the
core.
The core advantageously comprises, at least in the zone of the
widening or widenings narrowing towards the tube end, a
multiplicity of segments, which are axially and radially movable in
relation to one another. The segments advantageously consist of two
groups of segments, which intermesh in the manner of gear teeth, in
which connection, viewed in a plane normal to the axis of the core,
the segments of one group taper towards the axis, while those of
the other group remain uniform at least from the exterior to the
interior and preferably in width.
There is advantageously mounted on a rod which can be introduced in
the tube and carries the core, a thickening possibly conforming
with the tube widening, on which thickening the segments tapering
towards the axis are arranged with their ends turned away from the
tube end movable in radial planes of the axis, preferably
swivelably articulated.
The segments not narrowing in width towards the axis are
advantageously arranged on a core member conjointly forming, if
necessary, the tube widenings, and are displaceable axially to the
thickening, and movable in radial planes, preferably swivelably by
being articulated.
Stops are advantageously provided preferably at the thickening and
the core member which restrict the mobility of the segments
outwards.
There is advantageously provided inside the core, and preferably
.[.displacably.]. .Iadd.displaceably .Iaddend.on the rod, an
axially displaceable segment control and holding member. In the
moved-in position in the core, the control and holding member
presses, by corresponding surfaces, the segments into their
radially extreme position, while in the moved-out position, it
leaves the segments free for inward movements.
The control and holding member is advantageously provided with
stops, which swivel the segments at the core member inwards during
the outward travel of the core.
The control and holding member is advantageously provided with
stops, preferably engaging the segments of the core member, which
stops entrain the core member during outward travel.
A member, preferably a bar arranged in the rod, is advantageously
provided co-axially with the rod, for moving the control and
holding member.
The bar is advantageously connected with the control and holding
member by means of fingers engaging through recesses of the
rod.
The said thickening is advantageously a body widening the tube to
form the socket, which is externally complemented by the segments
sitting on it, while the totality of the segments have an annular
beading extending over their periphery, which produces a peripheral
corrugation in the sleeve.
The profiled cylinder is advantageously displaceable axially on the
rod.
A cooling device for the widened tube end, preferably a trickle
device, is advantageously provided surrounding the core at a
distance from it.
A heating device for heating the synthetic plastic material to the
softening temperature is advantageously provided.
Specific embodiments of the invention will now be described by way
of example with reference to the accompanying diagrammatic
drawings, in which:
FIG. 1 illustrates the upsetting of a tube string,
FIG. 2 shows on a larger scale the portion of the tube string
located in the calibrating collar during the thickening
process,
FIGS. 3 and 4 are exaggerated representations, showing in the upper
half (FIG. 3) the socket end of a synthetic plastic tube as known
in the art, and in the lower half (FIG. 7) a socket end produced in
accordance with the present invention,
FIG. 5 shows a section similar to FIG. 9, but with the core
collapsed so that the tube end can be withdrawn from the core,
FIG. 6 shows a device, partly in section, in accordance with the
invention for widening tube ends, after the widening of the tube
end and before the disengagement of the core and tube end,
FIG. 7 shows a section on line VII--VII in FIG. 6,
FIG. 8 shows the device of FIG. 6 after the disengagement of the
core and tube end,
FIG. 9 shows on enlarged scale a longitudinal section through the
core of the device shown in FIGS. 6 to 8, located in the finished
widened tube end, in which connection the calibrating and flexible
adaptation cylinder is still mounted over the tube end, this
section corresponding to section line IV--IV of FIG. 10, and
FIG. 10 shows a section taken on line X--X in FIG. 9.
There will now be described in connection with FIGS. 1 to 3, the
first step of the production of synthetic plastic tubes with ends
widened to form a socket, the tube wall being thickened before the
widening.
In FIG. 1 is diagrammatically represented the end face of an
extruder 71 having an aperture in which there is located a core 72
so that out of the aperture there is pressed a round synthetic
plastic tube 79 consisting of, for example, polyvinyl chloride. The
wall thickness of the tube 79 is determined by the difference in
diameter between the extruder aperture and the core 72. To the
extruder is connected a hollow calibrating collar 73, in which cool
water circulates.
At a distance from the calibrating collar 73 is provided a cooling
water bath 74 which cools the finished tube emerging from the
calibrating collar 73 so that this tube can be gripped, without
being damaged, by a draw-off device which operates at the same
speed as that at which the tube is pressed out of the extruder. The
draw-off device consists, in the embodiment shown, of radially
spaced rollers 75, which advance the tube. According to the
invention there is provided a conventional drive 76, for the
draw-off device, including an automatic control device of
conventional type, which decreases the speed of the draw-off
intermittently.
At predetermined time, the draw-off speed is reduced by the control
device by a given percentage such as, for example 20%. However, the
quantity of the synthetic plastic material emerging from the
extruder is not decreased and thereby during operation at reduced
drawn-off speed there is produced, by the heaping up of material
(upsetting) directly following the discharge aperture of the
extruder, a tubular section with a correspondingly increased wall
thickness, as is more clearly shown in FIG. 2. If the draw-off
device now begins to run at normal speed again, there then follows,
adjacent the tubular section with increased wall thickness, a tube
portion of normal wall thickness.
In the vicinity of the calibrating collar 73, there may be provided
a device which, for example by means of compressed air fed through
the core 72, maintains an overpressure inside the tube string
produced.
To show an example of the above method of operation, the following
data is given.
A tube of polyvinyl chloride with an external diameter of 100
millimeters (mm.) and an internal diameter of 80 mm. is to be
extruded. The polyvinyl chloride has a tensile strength of 5 to 5.5
kilogram per square millimeter. The wall thickness of the tube,
normally 10 mm. shall after 6 meters be increased to 20 mm. for a
length of 0.5 meters. The thickening of the wall shall be on the
inside of the tube wall. The extrusion speed and the draw-off speed
are 1.5 meters per minute during the extrusion of the normal tube
length. The extruder aperture is the usual one for extruding tubes
of the above mentioned dimensions. The temperature at the extruding
aperture is also usual, preferably being between 120 and
140.degree. C. After the extruding of 6 meters of tube length, the
draw-off speed of the draw-off device is reduced to 0.844 meters
per minute without changing the extrusion speed. Now the extruder
will deliver a portion of tube string with an external diameter of
still 100 mm. The internal diameter of this portion however will be
60 mm. After extrusion of a length of 0.5 meters of a so walled
tube the draw-off speed again is increased to 1.5 meters per
minute. Now the thickly walled part of the tube string will again
be followed by a normally walled part and so on.
Generally is to be mentioned, that the relation between the
cross-section areas and the draw-off speeds is given by the
formula: ##EQU1##
In this formula v is the draw-off speed and a the cross-section
area.
It is of importance in the process in accordance with the invention
that in treating the synthetic plastic material the production of
the zone of increased wall thickness be effected before the
synthetic plastic material, for example polyvinyl chloride,
polyethylene or other thermoplastic material, has been completely
polymerized. If the upsetting is effected after final
polymerization with a renewed heating of the corresponding tube
portion, this has the disadvantage that, with the subsequent
heating, the upset portion has a tendency to assume again the shape
which it had before the upsetting.
The tube string produced in the manner described above is now cut
into individual tube components each having a thickening at the
end. The upset ends are then brought into a female die, heat being
applied, if for example they are to be widened to socket ends of
increased diameter, in which female die they are widened in known
manner to the desired diameter and the desired form. In this way
there can be produced widened socket ends into which tube ends of
normal diameter can be inserted. In the course of the widening
process there may be produced during the same operational sequence
an annular groove in the socket end, which groove accommodates a
sealing ring. A socket end 77 thus produced is represented in FIG.
4, while its upper half shows a similar socket end 78 of known
type.
In a similar way the tube end can also be widened for example in a
female die provided with a female thread, so that the tube end has
a reinforced end with a male thread. The dimension given to the
upset portion and the die must be such that after the working in
the die the bore of the tube in the vicinity of the thickened end
is substantially equal to the normal diameter of the tube.
In a similar way it is also possible to thread a widened tube end
by inserting it in an inner male die.
The upsetting process described is particularly suitable for
working synthetic plastic material like polyvinylchloride or
polyethylene.
The widening of a tube end for an insert socket will now be
described with reference to FIGS. 6 to 10.
In FIGS. 6 to 8 is shown a holding device 1 for a tube to be
widened at its end, and also a core 2, a calibrating and
flexible-adaptation cylinder 3 and a movement device 4 for the core
and the cylinder.
The holding device comprises chucking jaws 6, axially movable and
supported on rods 5, which chucking jaws can grip the tube 8 under
the control of a hydraulically actuated chucking cylinder 7. The
two chucking jaws 6 are supported by plates 9 and 10, which are
pivoted on the spindle 11. For axial displacement of the chucking
jaws and the tube held thereby, there is provided a hydraulic
cylinder 12 which engages the plates 9 of the chucking jaws by
means of rod 13.
A rod 15 fixed to the device frame 14 carries the core 2. For
collapsing the core 2 there is used a hydraulic cylinder 18, which
by means of a bar guided inside the rod 15, collapses the core, in
a manner which will be hereinafter described, to such an extent
that the widened tube end can be drawn off the core. The
calibrating and flexible adaptation cylinder 3 is guided on the rod
15 and is moved axially by the hydraulic cylinder 16. For this
purpose there is mounted on the thrust rod 17 of the hydraulic
cylinder 16 a disc 19, which engages via two rods 20 with the
calibrating and flexible adaptation cylinder 3.
In the embodiment shown, the tube end is to be widened to form a
socket which has an annular corrugation 21 (FIG. 11). For this
purpose the device is first brought into a position in which the
core 2 is closed, while the cylinder 3 however has travelled to the
left into the position shown in FIG. 8. The tube 8 to be widened is
chucked in the chucking device after its end is first heated by the
heating device 22, which has been only indicated diagrammatically,
to the thermoplastic softening temperature of the tube 8. The core
is previously externally lubricated with a lubricant, for example
oil. The tube is now moved on the core, the end of the tube, whose
wall thickness has already been thickened, being pushed over the
core. As the plastic material of the tube end has a certain amount
of elasticity, it passes over the annular beading 23 of the core
and flexibly adapts itself to the core 2, narrowing to the left of
the annular beading. The cylinder 3 is now moved onto the tube end
in such a way that it fits with its correspondingly formed inner
surface into the portion of the tube located to the left of the
corrugation 21 produced in the tube end, and flexibly adapts itself
to the core. This flexible adaptation primarily insures that the
zone of the internal surface of the socket, indicated in FIG. 11 by
x, is itself in a markedly curved form, accurately and flexibly
adapted to the core.
When the tube end has received the desired widening and profiling
operation, then by means of the diagrammatically indicated cooling
device 24 (FIG. 8) consisting of a trickle installation, the
portion of the formed tube end not covered by the cylinder 3 is
sprayed and further solidified by the resulting cooling. Then the
cylinder 3 is moved to the left and the part of the tube end
hitherto covered by the cylinder is likewise solidifed by the
spraying. Finally, by means of the hydraulic cylinder 18 the core
is collapsed in a manner hereinafter described so that the tube can
be drawn from the core by means of the hydraulic cylinder 12. Then
the next tube end can be widened and profiled in the same
manner.
In the following, the construction and mode of operation of the
core will be described in connection with FIGS. 9 to 11.
In FIG. 9 is shown the cylinder 3, in order that its interior may
be better understood. It is provided with threaded holes 25, in
which the rods 20 are engaged.
The core, as already explained above, is carried by the rod 15. At
the end of the rod 15, a core thickening 27 is fixed and secured
against rotation by means of a key 26. This core thickening is held
by a nut 28 on a tapered portion 29 of the rod 15. The thickening
27 consists of a base body 30, on which a collar 32 is fixed by
means of screws 31. The collar 32 projects with its annular collar
33, surrounding the nut 28, into the zone of the tube 8 which is
not to be widened, collar 33 serving for guide purposes. The tube 8
is shown in FIGS. 9 to 11 in the finished widened condition. The
base body 30 has on its periphery, regularly distributed at a
distance apart from one another, six release or tripping devices 34
(FIG. 10) in which segments 35 are supported so as to be able to
swivel around spindles 36. These segments 35 have, as can be seen
in FIG. 10, wedge-shaped profiles in planes normal to the axis of
the cores. In particular they only have this profile in the zone in
which they come into contact with the segments 37. In their portion
further to the right in FIGS. 9 and 10 for production reasons they
have rectangular profiles, which facilitates their bearing on the
release devices 34 of the base body 30.
A control and holding cylinder 41 provided with release devices 39
and 40 associated with each of the six segments 37 is supported
axially displaceably on the rod 15 by means of the bar 16. The
connection of the bar 16 with the control and holding cylinder 41
is effected by means of a pin 42 which projects through elongated
slots 43 in the rod 15. By means of its surfaces 44, the cylinder
41 holds the segments 35 in their extreme position shown in FIGS. 9
and 10. This position is outwardly restricted by the stop surfaces
46 of an annular core member 47, which is applied against the
corresponding surfaces of the segments 35 as the core moves
together. The core member 47 consists of an annular body 48, which
partly projects by an outer collar 49 in relation to a second
annular body 50 likewise associated with the core member. The
annular bodies 48 and 50 are connected by screws 51. The annular
body 50 has six release devices 52. In each of these release
devices a segment 37 is supported so as to swivel around the
spindle 53. The segment 37, as can be seen in FIG. 9, has lateral
surfaces 54 extending parallel to one another, so that they can
still be swiveled inwards while they are between the segments 35.
Their extreme position is determined by the application of their
surfaces 35 to the corresponding surfaces of the control and
holding member and also by application of their surfaces 56 to
corresponding surfaces of the base body 30. The segments 37 are
provided with fingers 58, which can cooperate with corresponding
surfaces 59 of the release devices 39 of the control and holding
cylinder 41.
There will now be described the movement of the core between the
position shown in FIG. 9 and the position shown in FIG. 11. For
this purpose the bar 16 and the control and holding cylinder 41
connected with it are moved to the left, as far as is permitted by
the axial slots 43 in the rod 15. With this movement the surface 59
first abuts against the finger 58 of the segment 37 and swings this
finger inwards into the position shown in FIG. 11. As the member 41
slides to the left the surfaces of the segments 37 cooperating with
the surfaces 56 finally come into engagement with the surfaces 60
of the release devices 40 in the position shown in FIG. 11. Then
the member 41 also entrains, by engaging against the segments 37,
the core member 47 which is supported so as to be able to move
freely and axially on the periphery of the control and holding
cylinder 41. The segments 37 swiveled inwards, as described above,
no longer project into corrugation 21 so that they can be withdrawn
from the tube end. With the travel to the left of the control and
holding cylinder 41 the swiveling inwards has uncovered its surface
44 to free the segments 35, so that these, when the tube is
withdrawn from the core, can be swiveled inwardly under the
influence of the tube wall, into the position shown in FIG. 10, as
the tube is withdrawn.
After the tube is drawn off, the control and holding member 41 is
again moved, by means of the bar 16, to the right whereby it moves
the segments 35 back again to their outward positions. With further
displacement of the member 41 towards the right, the surfaces 65 of
the release devices 40 pivot the segments 37 such that surfaces 55
slide on the surfaces 66. Since the control and holding member,
when the core sections have moved together, presses with ring 67
against the annular body 48, the whole core is firmly held
together.
Attention is invited to the fact that elements 35 and 37
cooperatively constitute a male die having a continuous surface.
This male die is, further, collapsible. This feature is
advantageously effected by interdigitating elements 35 and 37 and
pivoting them on different pivots while providing the elements 35
with a wedge-shaped cross-section and the elements 37 with a
rectangular cross-section. As a result, it is possible firstly to
withdraw elements 37 from between the elements 35 after which the
latter can be collapsed.
It should be noted in further accordance with the invention that
the core can be heated before the application of the tube end, in
order to prevent a premature setting of the latter.
The invention is not restricted to the examples described, but is
in fact susceptible of variation within the scope of the following
claims.
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