Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FLOW DISTRIBUTOR FOR DIE TOOLING OF PIPE MOLD EOUIPMENT
WITH REMOTE EXTRUDER
FIELD OF THE INVENTION
The present invention relates to equipment
including an extruder and die tooling used in the molding
of plastic pipe.
BACKGROUND OF THE INVENTION
A traditional plastic pipe molding apparatus
includes an extruder which feeds molten plastic directly
to one or more interior passages of die tooling which
leads to a molding region of the extruder. The one or
more die passages can be used to make single or even
ribbed pipe.
The above apparatus suffers from the drawback that
the extruder and the die tooling are fixed in position
relative to one another. This necessitates relative
large die tool which is expensive and which takes a
substantial amount of time to heat. Space saving and
heating benefits can be achieved by locating the extruder
at a location remote from the die tooling and then using
a plastic feed from the extruder to the die tooling.
However, according to known practice, these benefits are
more than offset by the fact that with the current design
i.e., the design of the extruder being fixed relative to
the die tooling the extruder is able to feed directly
into the die passage of the tooling. Accordingly,
distribution of the plastic from the extruder around the
mouth of the die passage is achieved in a relatively
simple manner. The same is not true when working with a
remotely located extruder which will not necessarily
align directly with the mouth of the die passage.
Accordingly, using existing technology it is very
difficult to take advantage of the benefits provided when
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separating an extruder from die tooling equipment of a
pipe molding apparatus because such separation makes it
very difficult to produce an even distribution of molten
plastic from the extruder into the die passage. Without
such even distribution the resulting pipe is produced
with inconsistencies in the wall or walls of the pipe.
SUN~ARY OF THE PRESENT INVENTION
The present invention relates to equipment used in
the molding of plastic pipe which takes advantage of the
benefits achieved by separating an extruder from die
tooling without suffering from the drawbacks of such a
separation.
More particularly, the present invention relates
to equipment used in the molding of a plastic pipe in
which the equipment comprises a plastic supply providing
molten plastic for making the pipe and die tooling which
is located remotely of the plastic supply.
The die tooling has an internal die passage to
carry the molten plastic to a molding region where the
pipe is shaped. It further has an upstream end fitted
with a flow distributor. The die passage has a ring
shaped mouth covered by the .flow distributor at the
upstream end of the die tooling.
The equipment further includes a plastic feed from
the plastic supply to the flow distributor. The flow
distributor is then adjustable to produce an even
distribution of the molten plastic. which it receives from
the plastic supply around the ring shaped mouth of the
die passage.
According to an aspect of the invention the die
tooling has multiple passages and the flow distributor
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has multiple outlets which are adjustable for each of the
die passages.
According to another aspect of the invention the
equipment uses a single extruder which feeds to the
multiple flow outlets of the flow distributor. According
to yet another aspect of the invention the equipment uses
multiple extruders each of which feeds to an individual
one of the flow outlets from the flow distributor.
According to still another aspect of the invention
the equipment uses multiple extruders which can for
example, be used to extrude different types of plastic
materials. Each of the extruders feeds to each of the
flow outlets from the flow distributor. In this aspect of
the invention the equipment further includes valve means
to selectively open and close each of the extruders to
the flow distributor so that one can choose which one of
the extruders is to be used in making the pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
The above as well as other advantages and features
of the present invention will be described in greater
detail according to the preferred embodiments of the
present invention in which;
Figures 1, 2 and 3 are all schematic views of
equipment used in the molding of plastic pipe according
to different embodiments of the present invention;
Figure 4 is a front view of the plastic flow
distributor used in any one of the embodiments of Figures
1, 2 and 3;
Figure 5 is a cross sectional view of the flow
distributor of Figure 4 looking through the side of the
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flow distributor;
Figure 6 is a sectional view through the flow
distributor of Figure 4 when looking from the rear of the
flow distributor;
Figure 7 is a front view of the flow distributor
of Figure 4; and
Figures 8 and 9 are side and rear views
respectively of the flow distributor of Figure 4.
DETAILED DESCRIPTION ACCORDING TO THE PREFERRED
EMBODIMENTS OF THE PRESENT INVENTION IN WHICH:
Figure 1 shows molding equipment generally
indicated at 1 used in a pipe molding operation for
forming plastic pipe. Equipment 1 comprises an extruder
2 which feeds to die tooling generally indicated at 3.
This die tooling receives, as to be described later in
detail, molten plastic from the extruder and delivers it
to a mold region (not shown) in which the plastic pipe is
formed. Typically this mold region is made up of a
plurality of moving mold blocks having profiled faces for
shaping the pipe. Located within the mold region is a
cooling plug 7 against which the interior surface of the
pipe is formed.
In the embodiment shown, die tooling 3 includes
first and second die passages 4 and 9 respectively. Die
passage 4 has a passage outlet 5 and die passage 9 has a
passage outlet 11. These two passages which extend
longitudinally of the die equipment have a ring like
configuration with passage 9 being located outwardly
around passage 4. Each of the passages has a ring shaped
mouth at the upstream end of the die tooling 3 which is
covered by a plastic flow distributor generally indicated
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at 25. This plastic flow distributor is in the form of a
plate also to be described later in detail.
As can be seen in Figure 1 of the drawings
extruder 2 is located remotely of die tooling 3. This
achieves a number of benefits. Firstly, the die tooling
itself is substantially shorter in length than
conventional die tooling using an onboard extruder, e.g.
the die tooling is probably half the length or less of
conventional die tooling. With this arrangement there
are substantial savings with respect to the actual die
tooling and furthermore the die tooling is much more
easily and quickly heated than conventional die tooling.
In addition, the remote location of the extruder 2
relative to die tooling 3 does not require at a single
location the large space necessitated by die tooling
having an onboard extruder. In contrast, the die tooling
itself can be placed in one location with relatively
small space requirements and the extruder can be placed
in another location.
According to the present invention a plastic feed
generally indicated at 15 extends from extruder 2 to flow
distributor 25. In order to do so the product feed
comprises an individual conduit 17 feeding directly off
of extruder 2. Conduit 17 eventually leads to branch
feed lines 21 and 23 with a connecting branch between
branches 21 and 23. A metering device generally
indicated at 19 is provided at the mouth of branch 20
where this connecting extends from branch line 21 to
branch line 23.
The plate construction of flow distributor 25
comprises a first plate portion 27 having outlets 29
which align with the mouth of die passage 9. Branch line
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21 connects with the flow distributor so as to feed
through the outlets 29 of plate portion 27 into die
passage 9.
The plate construction of the flow distributor
further includes plate portion 31 having outlets 33 which
align with the mouth of die passage 4 at the upstream end
of the die tooling. Branch line 23 connects with plate
portion 31 so as to feed through flow distributor outlets
33 into die passage 4.
By way of example only, Figure 4 shows the rear
surface of flow distributor 25. Here it will be seen that
the outlets from the two plate portions are not localized
but rather are distributed around the mouths of the two
die passages. This is highlighted by the solid line flow
path markings of Figure 4. Further features of the flow
distributor will be later described with respect to
Figures 5 through 9 of the drawings.
Returning to Figure 1 the plastic from extruder 2
flows along conduit 17 as far as meter 19. This flow
meter which is adjustable for flow distribution purposes
will set the amount of molten plastic to flow along line
21 and along connecting line 20 to line 23. Line 21
feeding through flow distributor 25 is used to carry
plastic to die passage 9 feeding into the mold tunnel
through passage outlet 11 in forming part of the pipe
wall while line 23 feeds plastic through the flow
distributor into passage 4 and out outlet 5 in forming
another part of the pipe wall.
Figure 2 shows a further embodiment of the
invention in which the equipment uses two extruders 2a
and 2b rather than the single extruder shown in Figure 1.
This setup uses the same die tooling 3 and same flow
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distributor 25. It additionally uses the same branch or
feed lines 21 and 23.
What differs between the Figure 1 and Figure 2
embodiments is that in Figure 2, individual conduits 17a
and 17b extend from the two extruders 2a and 2b.
Conduits 17a feeds directly to branch line 21 which in
turn feeds directly to die passage 9. Conduit 17b feeds
directly to branch line 23 which then feeds to die
passage 4. There is no connecting passage between the
branches 21 and 23. Accordingly in this embodiment one
part of the pipe wall i..s formed from the plastic of one
of the extruders and another part of the pipe wall is
formed from the plastic of the other extruder.
Another feature of the present invention which is
used in both the embodiment of Figure 1 and the
embodiment of Figure 2 is the provision of ball
connectors 18 in each of the supply lines. These ball
connectors, which regardless of the position in which
they are set keep the plastic feed system in a closed
condition allowing different positionings of the
extruders relative to the die tooling.
Figure 3 shows another embodiment of the invention
once again using the same die tooling 3 fitted with a
flow distributor 25 at the upstream end of the die
tooling. The function and fitting of flow distributor 25
relative to the die tooling is identical to that
described with respect to Figures 1 and 2 of the
drawings.
In this particular embodiment the equipment
includes extruders 2c and 2d. These extruders can be
used to extrude different types of plastic materials to
the die tooling. They may also be used for extruding the
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same type of material. Furthermore, they can be used
simultaneously with one another or they can be used
independently of one another.
It will be seen that extruder 2c feeds from a
conduit 17c out of that particular extruder. Extruder 2d
feeds from a conduit 17d. A valve 41 is located in
conduit 17c and a valve 43 is located in conduit 17d.
Branch lines 21 and 23 feed to flow distributor 25
in the same manner as shown in Figures 1 and 2 of the
drawings. A connecting branch 22 connects across the
upstream ends of branches 21 and 23. A valve 45 is
located in connecting branch 22.
By closing valve 45 in connecting branch 22 and by
having valves 41 and 43 open the equipment of Figure 3
operates in the same manner as the equipment shown in
Figure 2, i.e., conduit 41 feeds along branch 21 to the
flow distributor. Conduit 43 feeds along branch 23 to
the flow distributor. No plastic is allowed to flow
across connecting branch 22. Accordingly, the plastic
from extruder 2c is used to make the part of the pipe
wall emanating from die passage 9 while extruder 2d is
used to make the part of the pipe wall emanating from die
passage 4.
In order to make the pipe entirely from the
plastic of extruder 2c valves 41 and 45 are opened.
Valve 43 is closed. In this configuration the plastic
will flow along conduit 17c past valve 41 and down branch
line 21. The plastic will additionally flow along branch
line 22 past valve 45 and down branch line 23. The
plastic cannot flow past the closed valve 43.
If it is desired to make the pipe entirely from
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the plastic of extruder 2d valves 43 and 22 are opened
and valve 41 is closed. Under these conditions the
plastic from extruder 2d flows along conduit 17d past
valve 43 and down branch line 21. The plastic
additionally flows along branch line 22 where it is
diverted by the closed valve 41 into branch line 21.
It will be seen from the description above that
even though much of the setup for each of the individual
embodiments is consistent from one embodiment to another
the equipment itself is extremely adaptive to use a
single extruder, multiple extruders and multiple
extruders extruding different types of plastic materials.
In each of these embodiments the die tooling is the same
as is the flow distributor used at the upstream end of
the die tooling.
One of the key features to the present invention
lies in the fact that the flow distributor and in
particular the two plate portions 27 and 31 are
adjustable at different locations around each of the
plate portions for the most efficient flow of plastic to
the die tooling. In Figures 3 and 4 of the drawings it
will be seen that the flow distributor 25 includes
numerous different adjustment members 51 and 53 which can
either be tightened or loosened to adjust the flow to the
outlets of the two plate portions relative to the die
passage mouths. Note that the adjustments of the plate
portions are done independently of one another.
For example, the flow of plastic to the flow
distributor from each of the extruders will be strongest
at the localized location where the plastic enters the
flow distributor. However, the plastic must be evenly
distributed or spread completely around the ring like
mouth of each of the die passages. Therefore the
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adjustment means must be setup to decrease the plastic
flow at or near the location where the plastic enters the
flow distributor and to cause the plastic to flow more
evenly to the weaker flow areas at the passage mouth
farther away from the source of plastic. The provision
of multiple adjustment points around the periphery of the
two plate portions of the flow distributor enables the
required adjustments at each of the plate portions so as
to provide consistent wall thickness around the pipe
produced using the equipment.
More specific details with respect to the flow
distributor are shown in Figures 5 through 9 of the
drawings. For example, Figure 5 clearly shows that the
two plate portions 27 and 31 of the flow distributor are
integral with one another. Branch line 21 feeds through
plate portion 27 along passages 22 which outlet at the
openings 29 to the upstream side of the distributor
plate. As can be seen in Figure 5 these passages
penetrate through both the plate portion 27 and the plate
portion 31. Adjustment screws 53 are used to open and
close passages 22 to control plastic flow distribution to
the inner pipe wall through plate outlet openings 29.
Plastic flow branch 23 feeds through passages 24
directly into plate portion 31 bypassing plate portion
27. Passages 24 outlet at openings 33 which feed the
plastic for the formation of the outer pipe wall.
Adjustment screws 51 are provided in the flow passages 24
to adjust plastic distribution around the distributor for
the outer pipe wall. Note that even though adjustment
members 51 penetrate through pipe portion 27 to plate
portion 31 the adjustment of these members does not
affect the flow of plastic through passages 22.
Figures 8 and 9 show that the adjustment members
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51 and 53 are easily accessible from the rear of the flow
distributor plate.
Although various preferred embodiments of the
present invention have been described in detail, it will
be appreciated by those skilled in the art that
variations may be made without departing from the spirit
of the invention or. the scope of the appended claims.
