Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02539085 2006-03-09
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Device for Division of a Non-Newtonian Liquid Flowing through a Passage
DESCRIPTION
Technical Field
[Para 1] The present invention relates to a device for targeted division of a
non-
Newtonian liquid flowing through a passage.
Background of the Invention
[Para 2] In injection molding, molten synthetic materials (such as
thermoplastic
materials) are passed, for example, through a hot passage manifold system in
which there
are branches at certain points, into which the molten material supplied in one
passage is
divided between two discharge passages. These branchings are predominantly of
T-shaped
configuration.
[Para 31 In the case of a Newtonian liquid flowing through a circular passage,
a
parabolic flow velocity distribution of the liquid, subdivided into imaginary
concentric
hollow cylindrical layers sets In, the flow velocity being a maximum in the
center of the
passage- In such a liquid, the shear between the several imaginary hollow
cylindrical layers
of the liquid is approximately equal.
[Para 4) On the other hand, a non-Newtonian liquid, such as for example (hot)
liquid
plastic, behaves differently. In this case, the viscosity is dependent on the
shear, which is a
maximum near the wall of the circular passage. The less the viscosity, the
greater the
shear. As a result, the viscosity near the wall of the circular passage is at
a minimum. The
viscosity distribution of the melt over the cross section resembles a sharply
flattened
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parabola. In a simplified approximate view, this means that in the central
region of the
passage, the relatively viscous flowing melt behaves like a plug, with a flow
velocity
approximately independent of the radial location, whereas in the peripheral
region the melt
is more fluid, owing to the greater shear, and flows more slowly.
[Para 5] This behavior is illustrated in Figures 1 a - 1 c. Figure 1 a shows a
circular
passage through which a non-Newtonian liquid flows, for example a plastic
melt. Figure 1 b
shows the distribution of the flow velocity "V" over the cross section, and
Figure 1 c shows
that of the shear. The region "d" corresponds more or less to the
aforementioned plug.
(Para 6] If a non-Newtonian liquid flow of the type shown in Figure 1 is
diverted in a
rectangular (T-shaped) branching Ti of the passage and divided into two
separate flows Si
and S2, as shown in Figure 2, then the high-viscosity portion and the fluid
portion of the
liquid will be distributed over the cross section of the passage. The
distribution over the
cross-section is shown in Figures 3a - 3c where area HV represents the liquid
of high
viscosity and the remaining area LV represents the liquid of low viscosity. On
the
coordinate system drawn in Figures 2 to 5, the coordinates x and y lie in the
plane of the
drawing and the coordinate z runs perpendicular to the plane of the drawing.
Thus, the
high-viscosity HV portion of the non-Newtonian liquid will collect
substantially in the lower
portion (in the sense of the drawing) of the passage segments 2a and 2b shown
in Figure 2.
This is easily seen, since the viscous fluid (melt) supplied from the central
region of the
passage segment 1 will advance to the bottom 6 of the Tee, and only then be
deflected to
the left and right in the sense of Figure 2, as indicated by the arrows "a" in
Figure 2, while
the more fluid liquid flowing in the peripheral region of the passage 1 will
be deflected at
the very beginning of the branching of the passage, as indicated by the arrows
"b".
[Para 7] If the passage segments 2a and 2b shown in Figure 2 were very long,
than
gradually the natural distribution shown in Figure 3a would gradually be
reestablished. In
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practice, however, the passage segments are short, so that approximately the
distribution
shown In Figures 3b and 3c would be preserved as far as the next deflection in
a Tee.
[Para 8] If the liquid flowing in the passage segment 2a encounters the Tee
TZ, whose
lengthwise axis runs in y-direction, the distribution shown in Figure 4
establishes itself in
the discharge passages 3a and 3b. The view here is in flow direction of the
discharge
passage in question. In the discharge passages, we see a marked inequality of
viscous and
fluid portions as well as a marked asymmetry of these portions with respect to
the centers
of the passages.
[Para 9] The Tee T3 in Figure 2 has two discharge passages 4a and 4b running
perpendicular to the plane of the drawing (in z-direction). See Figure 2a,
which shows a top
view of this portion of Figure 2. After deflection in this Tee T2, the
separations of viscous
and fluid portions of the liquid as shown in Figures 5a and 5b result. In the
discharge
passage 4b emerging upward from the plane of the drawing in Figure 2, the
distribution
according to Figure Sc is established, and in the passage 4b entering the
plane of the
drawing in Figure 2, the distribution according to Figure 5b is established,
the view being
again defined by the Tee in flow direction of the discharge passage.
[Para 10] In injection molding, if the injection nozzles connected to an
injection molding
tool (mold) are supplied from passages in which the quantity distribution of
melt
components of different viscosity is unequal (for example Figures 4b and 4c),
and/or in
which the distribution of the melt is no longer rotationally symmetrical with
respect to the
longitudinal axis of the passage (for example Figures 3b and 5b), this may
lead to defects in
the cast injection molding products.
[Para 11] If we assume that a plate Is injected by way of a plurality of
nozzles distributed
over the area of the plate, the following defects may occur,
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[Para 12] If the portion of the fluid melt from the nozzles in the outer
region of the plate
is greater than from the nozzles in the inner region of the plate, then under
the instant
pressure of the entering melt, more melt will be forced into the injection
tool (injection
mold) in the outer region of the plate than in the middle region. This means
that the plate
will be supplied with more material per unit area in the outer region than in
the inner
region, with the result that the cast plate will comprise undular edges. If,
conversely, more
fluid melt is forced Into the injection mold in the inner region, then after
cooling of the
melt, the greater quantity of melt per unit area in the interior will lead to
a bulging of the
plate in the inner region.
[Para 13] Similar situations, though less troublesome, arise if the melt
portions in the
passage segments supplying the nozzle are distributed asymmetrically.
[Para 141 If, for example, each of the several injection nozzles of a hot
passage manifold
system injects a cup, then the unequal quantity distribution of viscous and
fluid melt among
various nozzles has the result that the cups will have different wall
thicknesses. An
asymmetrical distribution of the melt components may lead to that side of the
cup which
contains preferentially fluid melt becoming thicker than the opposed side of
the cup,
resulting in a bulged cup, and/or, where viscous melt enters into the mold, it
does not get
to the bottom of the mold.
Summary of the Invention
[Para 15] An object of the present invention is to develop devices by which
the
asymmetrical and/or unequal quantity distribution of liquid components of
different
viscosity due to the deflections described are minimized or eliminated insofar
as possible,
and/or their occurrence prevented.
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[Para 16] To accomplish this object, a first embodiment of a device for
targeted division
of a non-Newtonian liquid, for example a molten synthetic material flowing
through a
passage (1) is provided. The material has viscosity decreasing outward in
cross section in
flow through a T-shaped passage branching (T) which deflecting and dividing
the liquid
flow. A partition is positioned in the passage branching (T) which divides the
liquid flowing
counter from the supply passage segment (1) into two halves. The angular
position of the
part ition (11) preferably has a setting adapted to the distribution of the
differentially
viscous components of the liquid in the supply passage segment (1). With the
invention, a
division of the liquid between the discharge passages (2a, Zb) of the passage
branching (T)
is accomplished without a significant distribution of the differentially
viscous components
of the liquid.
[Para 17] With this embodiment of the invention, it is brought about that when
in the
supply passage segment of a preferably or substantially T-shaped passage
branching, the
melt components of different viscosity are not rotationally symmetrically
distributed.
Instead, in two discharge passage segments of the passage branches, the
proportion of the
melt components of different viscosity is substantially equal.
(Para 18] In a second embodiment of the invention, a deflector Is provided to
divide the
flow of the material.
[Para 19] In this second form of the device, in the supply passage segment of
a
preferably or substantially T-shaped passage branching, the quantity
distribution of the
melt components of different viscosity is rotationally symmetrical. In the two
discharge
passage segments of the passage branching, essentially the rotationally
symmetrical
distribution is preserved and also the proportion of the melt components of
different
viscosity in the two discharge passages is substantially equal. The
distribution pattern in
the discharge passage segment is thus essentially the same as that in the
supply segment.
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The discharge passages may have the same cross section as the supply passage,
so
that the flow velocity in the discharge passages is reduced to half;
alternatively, however,
they may have smaller cross sections, so that the flow velocity is less
sharply reduced or
not at all.
In a broad aspect, the present invention provides a device for dividing a non-
Newtonian liquid material flowing through a supply passage, the liquid
material having a
flow-conditioned viscosity decreasing outward in cross section in flow through
a
substantially T-shaped passage branching (T) deflecting and dividing the flow
of liquid,
comprising a deflector positioned in said passage branching (T) for dividing a
central
viscous component of the liquid material from the supply passage segment prior
to its
deflection into discharge passages into two components, said two components
being
deflected in the region ahead of the discharge passages and flowing towards
each other
wherein the liquid flowing into the discharge passages has substantially
symmetrical
distribution of differentially viscous components of the liquid.
Brief Description of the Drawings
In the following, the invention will be illustrated in terms of embodiments by
way
of example and in terms of additional figures.
Figures 1 a - 1 c show the flow situation of a non-Newtonian liquid in a
cylindrical
passage.
Figure 2 shows a passage manifold system having three T-shaped passage
branchings.
Figure 2a shows a portion of Figure 2, in top view.
Figures 3a - 3c show the distribution of the at first symmetrical distribution
of the
viscous and fluid liquid components behind a first channel branching Ti.
Figures 4a - 4c show the distribution to which the melt continuing to flow on
from
the first passage branching Ti is subjected by a passage branching T2 in the
same plane as
the passage branching Ti previously passed.
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Figures 5a - 5c show the corresponding distribution as in Figure 4 at a
subsequent
passage branching T3 lying in a plane perpendicular to the passage branching
Ti
previously passed.
Figures 6a and 6b illustrate a first embodiment of the invention by way of
example
having in principle the structure of the first form of a device.
Figure 7 shows a practical example of the first type of embodiment of a device
according to Figure 6, built into a T-shaped passage branching.
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[Para 301 Figures 8a and 8b, in perspective representation, show a practical
example of
an embodiment of the partition plug employed in Figure 7,
[Para 31] Figures 9a and 9b, in perspective representation, show a practical
example of
the second type of embodiment of a device according to the invention, built
into a T-
shaped passage branching, in two sections at right angles to each other.
[Para 32] Figures 1 Oa and 1 Ob show a practical example of an embodiment of
the
deflector in Figures 9a and 9b in two views at right angles to each other, to
an enlarged
scale, supplemented by a fastening part.
[Para 33] Figure 11 shows a deflector according to Figure 10 as installed in a
Tee.
Description of the Preferred Embodiments
[Para 341 Figures 6a and 6b show an embodiment by way of example having the
structure. in principle, of a first type of device according to the invention.
In the passage
branching, a partition 11 directed at the supply melt is so installed that it
divides the flow of
melt coming from the supply passage segment 1. Here, the partition 11 is
placed at such
an angle of rotation that it parts the approaching melt, in which the liquid
components of
different viscosity are not distributed rotationally symmetrical with respect
to the
longitudinal axis of the passage, In such manner that the two partial flows
contain equal
quantities of liquid components of different viscosity.
[Para 35] If it is assumed that in the absence of the partition 11, the melt
would
distribute itself between the discharge passages in correspondence to the line
"t" shown in
Figure 6a, then a partition 11 placed in the angular position shown in Figure
6b can part the
approaching melt in such manner that the same proportion of viscous and fluid
liquid is
supplied to the two discharge passages. The partition 11 may be arranged in
the passage
branching In suitable manner with fixedly adjusted or adjustable angular
position.
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[Para 361 A practical embodiment of such a device according to the invention
is shown in
Figures 7 and 8, by way of example. In Figure 7, starting from the bottom 6 of
the T-
shaped passage branching, a bore 12 is made in the Tee. Into this bore 12, a
partition plug
to which a partition 11 is rigidly attached, is pressed in as far as the
middle of the
discharge passage segments 22a, 22b. Here, the partition plug, for example by
means of a
hexagonal socket 13, is rotated into the desired angular position, as was
illustrated by
Figure 6b. To prevent the plug 10 from being pushed out under pressure in
service, it is
fixed in its axial position by a screw plug 14, which may be screwed into the
bore 12 for
example by means of a hexagonal socket 15. The plug 10 is preferably a solid
body, having
a dome-shaped recess 16 at its end near the partition 11, in which the
partition 11 is rigidly
fixed in any manner by its side facing away from the supply passage segment 1.
The
requisite angular position of the partition 11 is determined by the rotational
position with
which the partition plug 10 is inserted in the bore 12. The retention of this
angular position
is achieved in any conventional manner, such as by a press fit, or by any
other additional
suitable rotational security,
[Para 37] Expediently, after the plug as previously described has been
installed in the
passage branching, the partition plug 10 starting from the discharge passages
22a and 22b
is bored to the diameter of the discharge passages in the region of the dome-
shaped recess
16, forming the (in projection) semicircular flow openings 17. Of course,
these flow
openings might instead be provided prior to installation on the partition
plug.
(Para 381 In Figure 7, for clarity, the partition 1 1 is represented in an
angular position
perpendicular to the plane of the drawing, and the openings 17 formed by the
boring are
represented as lying in the plane of the drawing. it will be understood that
in reality these
flow openings 17 lie rotated 90 , while the angular position of the partition
11 assumes an
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angular position in relation to the plane of the drawing, as shown in Figure
6b, adapted to
the distribution of the liquid components of different viscosity in the supply
passage 1.
[Para 39] In Figure 7, the bottom 6 of the passage branching is shown with a
reinforcement 18. This is required only when a commercial Tee, or the wall of
a hot
passage manifold block in which the flow passages are worked has an
insufficiently thick
wall.
[Para 40] Figures 8a and 8b show two perspective representations of the
previously
described example of the solid partition plug 10 with partition 11. Figure 8a
shows the
plug 10 before boring the dome-shaped recess 16, with indication of the rear
hexagonal
socket 13. Figure 8b shows the plug with the bores to be expediently made
after
installation and the resulting flow openings 17.
[Para 41) In a second embodiment of a device according to the present
invention, the aim
pursued is so to divide and deflect a flow of liquid with symmetrical
distribution of the
liquid components of different viscosity according to Figure 3a in a passage
branching that
this distribution is substantially preserved in the discharge passages of the
passage
branching.
[Para 42) If in Figure 9b it is assumed that the liquid in the supply passage
segment 21 is
distributed according to Figure 3a, then the distribution in the discharge
passage segments
22a and 22b will correspond to Figures 3b and 3c without more. But if one were
to supply
an equal flow of liquid to that supplied by the pipe 21 to the passage
branching from above
in the sense of the drawing, and additionally from below as well, it is easily
seen that the
viscous liquid component forced aside in Figure 9b into the passages 22a and
22b would be
shifted by the supposed additional liquid flow towards the center of the
passages 22a and
22b.
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[Para 43] This effect is realized by the second type of device according to
the invention
with an ordinary passage branching, In the second type of a device according
to the
invention, the viscous liquid component flowing in the center of the supply
passage
segment is divided, and the two components are deflected to meet each
substantially at
right angles at the entrances of the discharge passage segments, their
direction of flow at
this encounter being essentially perpendicular to the longitudinal direction
of the discharge
passages.
[Para 44] To accomplish this, in the passage branching there is a deflector
23, so
fashioned that it enters into the supply passage segment 21 with a blade 24,
and essentially
splits the viscous liquid component flowing in the center of the passage
segment 21 into
two components, one continuing to flow on the left and the other on the right
side of the
deflector 23. These components are deflected so they meet each other insofar
as possible
at right angles at the bottom end 7. In the sense of the drawing, of the
passage branching.
[Para 45] The web 27 on whose sides the two components of the viscous
component
impinge serves only for mechanical attachment of the deflector 23 in the
passage branch.
For the effect according to the invention, it is not required. The actual
deflector 23
preferably touches the passage segment 21 nowhere on its entire periphery.
(Para 46] Figures 1 Oa and 1 Ob show a practical embodiment of the deflector
23. The
said web 27 is adjoined by a cylindrical segment 31 which may continue in a
cylindrical
segment 32 of enlarged diameter. With said segment 31, the deflector is thrust
as far as
the position shown in Figures 9a and 9b and sealingly fastened, through a bore
in the
bottom of the passage branching.
[Para 471 In principle, any kind of fastening of the deflector 23 in the
passage branching
will suffice, for example by means of the struts 28 shown dotted in Figure 9a,
although this
might be difficult with passages of small diameters,
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[Para 48] The deflector 23 with web 27 and cylindrical segment 31 may be made
out of a
continuous cylindrical body, provided at its anterior end with the blade 24
and at its
posterior end with a constriction forming the web 27 by notches on both sides,
opposed to
each other and parallel to the blade 24. The opposed -sides 25 of the
deflector preferably lie
on circularly or similarly curved surfaces extending from the blade 24 to the
web 27 and
making a transition into surfaces of the original cylinder 31.
[Para 491 Figure 11 shows a deflector of the type of Figure 11 as installed in
a T-shaped
passage branching, Insofar as the reference numerals in Figure 11 correspond
to those in
Figures 9 and 10, they designate the same objects as in those figures.
[Para 501 Further details, benefits and features of the present invention will
become
available from the following description when taken in connection with the
accompanying
drawings.
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