Note: Descriptions are shown in the official language in which they were submitted.
~8221S
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TITLE OF TH~ INVENTION
"Pin-barrel extruder having adjustable pins"
5 FIELD O~ THE INVENTION
The present invention relates to a pin-barrel extruder.
More particularly, it relates to an extruder in which the pins are
adjustable.
BAC~GRûUND OF THE INVENTION AND PRIOR M T DISCUSSION
Pin-barrel extruders are known and comprise a screw conveyor
which is rotatable in the hollow interior of a barrel. Disposed
15 along the length of the barrel and projecting radially into the
hollow interior of the barrel are a plurality of pins. These pins
project to adjacent the core of the screw, the flight or flights
on the screw being discontinuous in the region of the pins.
It is desirable if the depth of penetration of the pins into
the barrel is adjustable. Such an arrangement is disclosed in
United States Patent Specification No. 4,178,104. In such
arrangement the pins are screw-fitted in holding members and
are non-rotatably connected thereto by means of lock nuts. The
25 holding fixtures are radially displaceable in guide members mounted
on the extruder cylinder. A gear member is used for adjustment
purposes. One face of the gear faces the holding fixture and is
provided with a cam track. The track engages corresponding
complementary cam-followers on the holding fixtures. The gear
30 member is driven by a pinion, is freely rotatable and is prevented
from axial movement by a collar ring.
However, such an arrangement suffers from numerous dis-
advantages. In setting up such an arrangement, the gear member
35 must firstly be positioned over the extruder barrel. In its end
position, it thèn has to be mounted on a sleeve-like guide means
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which, in turn, has to be screw-connected to the extruder barrel.
Finally, complementary cams and cam tracks have to be provided
laterally on the gear member and in the holding fixtures. This
is time-consuming and costly.
In addition, an extremely elaborate construction is also
required, for the mounting of the drive pinion which engages with
the gear on the extruder cylinder. This adds to the costs
associated with the production of an extruder having such an
adjustment arrangement.
It is also difficult to assemble the adjusting means. Before
a barrel flange connecting member, which is usually provided to
permit barrel portions to be connected together, is welded to one
end of a barrel portion, it is necessary for the sleeve-like guide
member to be slid onto the barrel so as to receive the bearings
for the gear. The gear is then positioned over the cylinder and
brought into its intended position. Only after this has been
done can the guide member be screw-connected to the extruder barrel.
The holding fixture, which is provided with the lateral cam follow-
ers, is then slid onto the extruder barrel into its intended
position. The individual pins are $crewed radially inwardly
through the holding fixture. Only when the assembly of all of
these integers has been completed, can the barrel flange be welded
to the end of the barrel portion.
After a period of time, it is likely that the cam followers
on the holding fixture and the cam track on the gear member will
exhibit signs of wear. To replace them, the above-described
procedure must be reversed. So much work is involved that it is
simpler to replace the entire barrel portion. Moreover, it is
also necessary to extract the screw from the extruder, and to
remove the barrel flange connection. These measures which need
to be taken mean that the extruder is inoperative for long, and
therefore costly, periods of time.
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OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to
provide a pin-barrel extruder in which the pins are
adjustable but in which adjusting means are of a very simple
construction and require little assembly and dismantling.
In particular, it is an object of the present invention to
avoid the necessity for extracting the screw of the extruder
and for disconnecting, by removing the weld, the flanges of
individual barrel portions when it is desired to change or
replace the means for adjusting the pins.
SUMMARY OF THE INVENTION
lS According to the present invention, there is
provided a pin-barrel extruder suitable for processing
rubber, thermoplastics materials and the like, comprising
hollow cylindrical barrel means, said barrel means com-
prising a radial inner surface and a radial outer surface,
screw means rotatable in said hollow cylindrical barrel
means, said screw means comprising a core portion and at
least one flight portion helically disposed around said core
portion, said at least one flight portion being
discontinuous, said barrel means defining radially dlrected
throughbores extending from said radial outer surface to
said radial inner surface, said throughbores being
distributed around the periphery of said barrel at substan-
tially uniform intervals, pin means disposed in said
throughbores, said pin means being directed radially
inwardly towards the longitudinal axis of said core of said
screw means and projecting into said hollow cylindrical
barrel means to adjacent said core through said disconti-
nuous portions of said at least one flight, and adjusting
means for adjusting the depth of penetration of said pin
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means into said hollow cylindrical barrel means, wherein
said adjusting means comprise hydraulic piston-and-cylinder
arrangements, each said arrangement comprising a cylinder
mounted on said radial outer surface of said barrel portion
and piston rod means slidable within each said cylinder,
each said pin means forming an end part of a selected piston
rod means.
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By making the pins form part of the piston rods, an extremely
simple and effective arrangement is achieved for adjusting the
pins. The depth of penetration of the pins into the hollow
interior of the barrel may be varied simply by moving the respective
piston rods in the individual hydraulic cylinders either radially
inwardly or radially outwardly.
The piston rods in the hydraulic piston and cylinder arrange-
ments mounted on the extruder barrel may be moved simultaneously
or merely all of the pins in a particular radial plane or in a
particular extruder barrel portion may be moved simultaneously, or
even individual piston rods may be moved. This permits a highly
individual adaptation to the specific temperature requirements or
viscosities of the materials being treated can be achieved within
the barrel portions.
Moreover, even if the screw needs to be extracted for cleaning
or any other purpose, the pins can be extracted from the extrusion
chamber extremely quickly, so that the screw can be extracted
easily.
Preferably, each said piston rod means comprises a piston rod
and a pin member detachably affixed to said piston rod.
Alternatively, each said piston rod means comprises a piston
rod and a pin member integrally formed with said piston rod.
Advantageously, each said piston rod means comprises a
further end part remote from said pin means, said further end part
projecting from said cylinder in a direction opposite said pin
means, said projecting further end part carrying indicia means.
BRIEF DESCRIPTION OF THE DRAWINGS
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35 - One embodiment of a pin-barrel extruder in accordance with
the present invention will be further described, by way of example,
with reference to the accompanying drawings, in which:
B;2;2~
Fig 1 is a longitudinal sectional view through a portion
of a pin barrel extruder in accordance with the present invention;
and
Fig. 2 is a cross-sectional view taken along the line II-II
5 of Fig. 1.
DESCRIPTION OF PREFERRED EMBODIMENTS
In Fig. 1, there is shown a pin-barrel extruder in which, in
a conventional manner, a screw 2 rotates in an extruder barrel
portion 1. Material to be extruded such as rubber or thermo-
plastics materials are fed into the barrel 1 and are conveyed
therealong by means of one or more helically extending flights 3
provided around the periphery of the screw 2. Pin members 4
15 provided along the length of the barrel portion 1 and project
radially inwardly into the interior 5 of the barrel portion 1.
The flights 3 are discontinuous in the regions where the pins 4
project into the interior 5 of the barrel portion 1.
To permit adjustment of the pins 4, hydraulic piston and
cylinder arrangements 6 are moùnted on the exterior surface of the
barrel portion 1. These arrangements are so designed that each
pin is integrally formed with, or is affixable to, a respective
one of the piston rods of the piston and cylinder arrangements.
The hydraulic piston and cylinder arrangements 6 are controlled
by means of one or more check valves (not shown). Depending upon
the intended purpose of the apparatus, the piston and cylinder
arrangements may be controlled in groups or all together.
By simply operating such a check valve or valves, it is
therefore possible to move the pins 4 into and out of the interior
5 of the barrel portion in a matter of seconds. Accordingly, the
apparatus can rapidly be adapted to cope with the viscosity and/or
35 temperature sensitivity of almost any material requiring extrusion.
22lS
The piston rods of the hydraulic cylinders may be continuous
so that one end thereof forms one of the homogenising pins 4
and the other ends, which projects from the hydraulic cylinder,
can also serve as a visible control means if it is provided ~ith
appropriate markings because it denotes the depth of penetration
of the pin end 4 into the interior 5 of the barrel portion 1.
Alternatively, the pins 4 may be separate integers which are
screw-threadedly affixed into the piston rods of the hydraulic
cylinders. Accordingly, if wear phenomena appear on the pins 4,
it is possible to replace the pins 4 in an economic and rapid
manner.
