Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STATIC MIXING ASSEMBLY
BACKGROUND OF THE~ INVENTION
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1. FIELD OF THE INVENTION
This invention relates to an assembly for mixing and
dispensing two liquid components.
2. DESCRIPTION OF THE REL_TED ART
Static mixing assemblies are in widespread use for
storing, mixing and dispensing two liquid components such
as two-part curable resins. For example, some assemblies
resemble a syringe having side-by-side barrels for storing
different liquid materials, and the syringe includes a
detachable exit conduit having a static mixer located
downstream of the harrels. ~s a piston assembly is
advanced in the syringe, liquid materials discharged from
the barrels are mixed in the static mixer and dispensed
through an outlet of the exit conduit.
A troublesome problem that has been noted in
connection with dispensing of certain material from static
mixer assemblies is the drippage or drooling of the
materials from the exit conduit after the intended end of a
dispensing operation. Users of hand-held static mixer
assemblies may remove the assembly from the work area to
avoid dripping additional mixed materials on the workpiece
and place the end of the exit conduit over a disposable cup
to catch drips. However, such a procedure represents an
annoyance and a waste of materials. Some users have
attempted to pull back the handles of the pistons in an
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attempt to avoid such problems, but it is often observed
that relief of pressure in the barrels does not completely
stop the drooling of material from the end of the static
mixer.
The problem of dripping from static mixers is
particularly noticeable when the mixer is part o~ a
stationary dispensing assembly that has an upright
orientation. Stationary mixers are often used in automated
manufacturing processes, and in these instances care must
be taken to insure that the workpiece does not remain
beneath the outlet of the static mixer once sufficient
amounts of mixed materials have been dispensed. Again such
drippage represents a nuisance and an expense that would
preferably be avoided.
SUMMARY OF THE INVENTIQN
The present invention relates to a static mixing
assembly that comprises a container having a first barrel
with an exit port, and a second barrel with an exit port.
The assembly includes a first piston movable in the first
barrel and a second piston movahle in the second barrel
simultaneously with movement of the first piston, for
ejection of materials from the first and second barrels
through respective exit ports. The assembly further has an
exit conduit with an inlet end, an outlet and means for
detachably connecting the inlet end to the exit ports of
the first and second barrels. The conduit includes a
static mixer located between the inlet end and the outlet
for mixing materials ejected from the first and second
barrels. Advantageously, the conduit includes a check
valve located between the static mixer and the outlet for
substantially preventing drippage of mixed materials from
the outlet after movèment of the pistons has ceased. As
such, the check valve may be discarded with the exit
conduit once the exit conduit is detached from the exit
ports.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a top, right and front side perspective view
of an assembly according to the invention with parts broken
away in section;
Fig. 2 is an enlarged, front, vertical sectional view
of a check valve of the assembly shown in Fig. l; and
Fig. 3 is an enlarged, front, vertical sectional view
of a check valve of an assembly according to another
embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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A static mixing assembly 10 is illustrated in Fig. 1
and includes an upright s~pport 12 that is secured to a
workpiece-holding table 14. A horizontally-extending arm
16 is fixed to an upper portion of the support 12. A
generally C-shaped holder 18 is connected to an outer end
of the arm 16 remote from the support 12.
The assembly 10 also includes a container 20 that has
a rectangular flange 22 which slidably fits into the holder
18. The container 20 includes a first elongated,
cylindrical barrel 24 and a second elongated, cylindrical
barrel 26 that is integrally molded with the first barrel
24 in side-by-side, parallel relationship. The container
20 is made of a synthetic resinous material, and is
normally supplied to the end user with different liquid
components in the barrels 24, 26. The slidable
interconnection between the flange 22 and the holder 18
enables the user to dispose of the container 20 once the
barrels 24, 26 are emptied, and thereafter install another
container in the holder 18.
The first barrel 24 has an exit port 28 adjacent its
lower end, and the second barrel 26 has an exit port 30
adjacent its ]ower end. Both of the ports 28, 30
communicate with separated, juxtaposed channels (not shown)
formed within a cylindrical, depending, threaded neck 32 of
the container 20.
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The assembly 10 further includes an elongated, tubular
exit conduit 34 with an upper frustoconical inlet end 36.
A means for detachably connecting the inlet end 36 to the
neck 32 of the container 20 comprises a collar 38 having
internal threads that mate with the threads of the neck 32.
The collar 38 is loose and, when rotated relative to the
exit conduit 34 while engaging the threaded neck 32, fixes
the inlet end 36 against the bottom of the neck 32.
Rotation of the collar 38 in the opposite direction enables
the collar 38 along with the exit conduit 34 to be detached
from the container 20 when desired.
A static mixer 40 is positioned within the exit
conduit 3~ between the inlet end 36 and a lower outlet 42
of the conduit 3g. The static mixer 40 comprises a
sequence of oppositely oriented mixing blades to thoroughly
blend the passing materials. As shown in Fig. 1, the exit
conduit 34 also carries a check valve 44 which is located
between the static mixer 40 and the outlet 42.
The check valve 44 is shown in more detail in Fig. 2
and includes a housing 46 having an upper end that contacts
the lower end of the static mixer 40, and a lower end that
is retained in place by a necked-down wall that form~ the
outlet 42. The housing 46 has an internal passageway 48
which receives a valve stem 50 having a head 52. The upper
end of the stem 50 is secured to a bracket 56 that, in
turn, retains a coiled compression spring 58 in place
within the passageway 48 and around the stem 50. The lower
end of the spring 58 rests against a shoulder formed in the
housing 46, and biases the stem upwardly such that the head
52 is urged toward a position of sealing contact with a
valve seat 60 formed in the hnusing 46.
Referring again to ~ig. 1, a dual acting piston and
cylinder assembly 62 is mounted atop the arm 16 and is
connected by shafts to a first piston 64 and a second
piston 66 that moves simultaneously with movement of the
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first piston 64. As air pressure is introduced to the top
of the piston and cylinder assembly 62 via tubing 68, the
piston of the assembly 62 descends and causes the first and
second pistons 64, 66 to move downwardly at the same time
in the respective barrels 24, 26.
Each of the barrels 24, 26 is adapted to contain
different liquid components. As the pistons 64, 66
descend, a portion of the liquid components are discharged
through the ports 28, 30, through neck 32 and into the
inlet end 36 of the exit conduit 34. As the pistons 64, 66
continue to move downwardly, the components are admixed
during movement through the conduit 34 and arrive at the
check valve 44 in a thoroughly mixed condition.
As long as pressure is exerted by the pistons 64, 66
on the liquid materials within the barrels 24, 26, the
materials will flow thLough the exit conduit 34 and enter
the passageway 48 of the check valve 44. As a result,
pressure of the descending, mixed liquids is exerted on the
stem 50 which shifts lonyitudinally in a downwardly
direction against the bias presented by the spring 58 to
unseat the head 52 and enable the mixed liquid materials to
flow past the check va:Lve 44 and through the outlet 42
toward a workpiece or other object.
Once air pressure on the tubing 68 is relieved,
pressure of the pistons 64, 66 on the liquid materials
within the barrels 24, 26 is also relieved which in turn
decreases the pressure of liquid materials in the vicinity
of the static mixer 40. At such time, the spring 58, in
contact with the bracket 56, pushes the stem 50 upwardly to
close the check valve 44 by engaging the top of the head 5.2
against the valve seat 60. Consequently, the check valve
44 substantially prevents unintentional drippage of the
mixed materials from the exit conduit 34 once pressure is
no longer exerted by the pistons 64, 66.
Typically, only a portion of the liquid materials
within the barrels 24, 26 is discharged into the exit
conduit 34 at the end of a day's operation or other,
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relatively long work interruption. In such situations, the
mixed components within the conduit 34 will cure or harden
to such a condition that subsequent ejection of mixed
materials through the outlet 42 is substantially difficult
if not impossible. Conse~uently, it is desirable for the
user to ~iscard the filled exit conduit 34 by rotation of
the collar 38 until the conduit 34 is completely separated
from the container 20. At that time, the user may simply
install a new exit conduit in its place.
Importantly, the check valve 44 is carried within the
conduit 34 and thus does not have to be cleaned at the end
of a dispensing operation. Instead, the check valve 44,
being of relatively inexpensive construction, can simply be
discarded along with remaining components of the exit
conduit 34 as soon as the liquid materials therein have
hardened to such a condition that further discharge of the
latter through the outlet 42 is rendered difficult.
Once the liquid materials within the barrels 24, 26
are exhausted, air pressure may be directed through a
second tube 70 which is connected to a lower portion of the
piston and cylinder assembly 62 in order to force the
piston of the latter in an upwardly direction, thereby
raising the pistons 64, 66 out of the container 20. The
user may then detach the container 20 from the arm 16 by
sliding the flange 22 out of the holder 18.
A presently preferred embodiment of the invention is
shown in Fig. 3 and includes a check valve 144 that is
received in a lower end of a disposable, detachable exit
conduit 134 of a static mixing assembly 110. The assembly
110 with the exception of the check valve 144 is similar to
the assembly 10 described in connection with Figs. 1 and 2.
The check valve 144 includes a cylindrical plastic
housing 146 having an internal, central, longitudinal
passageway 148. A spherical valve ball 151 located in the
passageway 148 is urged by a compression spring 158 toward
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a conical valve seat 160 formed in the housing 146. The
major extent of the spring 158 is of a constant outer
diameter smaller than the internal diameter of adjacent
portions of the passageway 148, but a lowermost end coil
159 of the spring 158 is larger than the internal diameter
of the passageway 148.
During construction of the static mixing assembly 110,
the check valve 144 is inserted into the entrance of the
exit conduit 134 with the end coil 159 protruding in front
of the housing 146. The check valve 144 is advanced toward
the outlet of the exit conduit 134 until one side of the
end coil 159 engages a radial shoulder 135 formed in the
housing 146 while the forward end of the housing 146 is in
contact with the opposite side of the end coil 159. In
this manner, the spring 158 is captured and a separate
fastener or the like is not needed.
The check valve 144 is believed to provide higher flow
rates of material through the passageway 148 in comparison
to the check valve 44 for a given amoun~ of pressure
exerted on the material. Moreover, it is believed that the
check valve 144 provides a faster, more positive shut-off
of materials flowing through the exit conduit 134 than the
check valve 44. Also noteworthy is the reduced overall
length of the check valve 144 in comparison to the check
valve 44, which enables a greater length of static mixer
(such as mixer 40) to be received in a given length of exit
conduit 13g.
In either of the embodiments, the check valve 44, 144
is advantageous because it is constructed in cartridge-like
fashion and can be used with conventional exit conduits
without fasteners. Generally, the snugness of fit between
the static mixer and the exit conduit is sufficient to hold
both the static mixer and the check valve in place in the
exit conduit even when the exit conduit is inverted from
the position shown in the drawings.
