Segmented barrel extruder feeder device

A segmented barrel extruder device for extrusion and having a plurality of segments enclosing an extruder barrel aligned on an axis. The segments include axially perpendicular rectangular end flanges having exposed sides and a central portion for housing an extruder barrel. The flanges have aligned straight line paths for fluid flow in a plane perpendicular to the axis. Accordingly, the paths each intersect two exposed sides without intersecting the central portion. The segments also include an extruder bore between the flanges. The segments have a housing having straight axial channels which are connected to the paths in the flanges to conduct fluid from points along one path in each path to of points along a corresponding path. The extruder bore also includes a centered portion aligned with the flange central portion and a radial feeder device. The radial feeder device includes a seal and a mount which is adapted to mount the seal without sealing force on the bore. Finally, the device includes an inlet and an outlet for fluid flow.

The present invention relates to an improved segmented barrel extruder 
device, and more particularly to a feeding device for extruders operating 
along a longitudinal axis. More specifically, the invention relates to an 
improvement in the extruder barrel feeder while also providing a seal 
mechanism which substantially improves operational economics and 
efficiencies without harm to the extruder bore. 
BACKGROUND OF THE INVENTION 
Machines for plastic compounding have existed for many years now, and have 
progressed through many generations of development as technology improves 
and as plastic formulations change and place new demands on the 
compounding equipment. During this development, it has become technically 
and economically desirable to operate continuous processes. 
For example, most production from linear low density polyethylene includes 
a continuous extruder machine. Polypropylene and EPDM, PVC (both rigid and 
flexible), thermoplastic rubbers, EVA, PE generally, and specialty 
formulations for video discs and records are other examples of compounding 
successes on continuous extruder machines. 
The most effective continuous extruder designs are those which employ a 
twin screw extruder which is self cleaning and able to provide high 
capacity. The most efficient systems allow for multiple formulations to be 
processed on the same extruder, with the opportunity to customize the twin 
screw alignment for particular needs. Also used in some specific 
situations are single screw extruders, when the chemical and physical 
properties of the product require that treatment. 
As is well known, chemical reactions in general and plastic production 
specifically needs to be controlled so that the reaction rate is maximized 
without adverse side effects. Thus heating and cooling functions are 
required, to maintain the plastics at a maximum efficiency. However, it is 
in this area that machines for continuous extrusion of plastics and the 
like have their most difficulties. 
For example, polyethylene may be extruded at 200.degree. to 250.degree. F., 
while nylon is processed at about 650.degree. F. In both cases, excessive 
heat will cause degradation of the expected properties, while low heat 
will lead to longer reaction times or incomplete reactions. Each chemical 
system has its own needs, as some are strongly exothermic while others 
need heat to be added to drive the reaction. Sometimes, the fillers, 
coloring agents, flame retardants and the like call for special 
temperature considerations. Thus the extruder must meet a wide range of 
operating conditions if it is to be useful over any reasonable range of 
products. 
Heating can be accomplished with electric heaters, steam or hot oil for 
example, while cooling is done with water or air. It is also possible to 
control temperature by controlling the rate of the extruder screws, so 
that faster or slower rates enhance or retard exothermic or endothermic 
conditions as needed. Nevertheless, there presently does not exist an 
extruder system which can accommodate any significant part of the total 
market, particularly where different temperature conditions must be met 
for each varied chemistry. 
Conventional extruder technology is not capable of accommodating the wide 
range of temperature conditions in a single machine. Of course, the 
requirements of any particular chemistry can be designed into a machine 
system, but the likelihood of that machine being usable for other systems 
is small. Thus it would be a great advance in the art if an extruder 
system could be provided which would operate over a wide range of 
temperature ranges, both for heating and cooling. 
Presently, heater bands are wrapped around the segments of an extruder 
system, so that heat can be applied electrically at desired locations. 
These heaters provide a heat for melting, mixing and driving the reaction. 
Electric heat is effective in most systems but is limited by the specific 
design which is installed on any given unit. By this is meant that 
electric heating might be installed for a particular temperature and heat 
exchange range of conditions, but that unit might not be usable for other 
conditions. 
Under these circumstances, additional heating is provided, usually by steam 
or hot oil. This form of heat requires that there be access to the region 
near the extruder path in order to be effective. To date, no effective 
system has been provide to accommodate this need. 
Cooling in the present generation of extruder machines is done by a number 
of somewhat effective but not perfect designs. Single screw extruders are 
actually thick walled piping, and cooling is applied by wrapping a spiral 
coil around the pipe. Heat transfer is effected in a spiral path, but this 
has been found to be generally acceptable for single screw units. 
Double screw extruders are much more complicated, of course, and spiral 
wrapping of cooling coils has not been nearly as effective in providing 
fast, direct cooling to the product as it is carried, mixed, and reacted 
by the twin screw design. In addition, twin screw or double screw 
extruders achieve substantially greater mixing per unit of length, so that 
both cooling and heating control needs to be faster and more precise. 
Still, the only method used by the prior art is to wrap the double screw 
segments with heater bands. Cooling as also achieved by direct contact 
with the outside of the barrel segment. This does not present an even 
temperature profile to the mixing and extrusion zones. Thus mixing rates, 
reaction conditions and overall process efficiencies are limited more by 
the temperature control than by the capabilities of the extruder itself. 
A major problem in extruder devices, and particularly in those extruder 
devices which are used for extruding formulations which contain fiberglass 
and other abrasive materials is providing access to the pair of bores at a 
location which allows for easy insertion of materials without affecting 
the cooling system. The action of screw extruders at controlled but 
elevated temperatures requires rapid insertion of materials into the 
flight paths without placing stress or other forces on the extruder bore. 
Accordingly, it is an object of the present invention to provide an 
improved feeder assembly for radially introducing material into the 
extruder bore with out interfering with the heating and cooling operation. 
Another object of the present invention is to provide an extruder device 
feeder assembly which can be sealed to protect the extruder process during 
operation. 
Yet another object of the present invention is to provide a mounting means 
for a radial feeder assembly which places substantially no strell or other 
forces on the extruder bore. 
Other objects will appear herein. 
SUMMARY OF THE INVENTION 
It has now been discovered that the above and other objects of the present 
invention may be accomplished in the following manner. Specifically, a new 
segmented barrel extruder device for extrusion along a longitudinal axis 
has been discovered. The device has a plurality of segments enclosing a 
barrel aligned on that axis. 
The segmented barrel extruder device of the present invention is designed 
for extrusion along a longitudinal axis. The device has a plurality of 
segments enclosing an extruder barrel aligned on the longitudinal axis. 
The segments comprise a pair of axially perpendicular rectangular end 
flanges for each segment and having exposed sides and a central portion 
for housing the extruder barrel. Each end flange has a plurality of 
aligned straight line paths for fluid flow into and out of the flange in a 
plane perpendicular to the longitudinal axis. Each straight line path 
intersects two exposed sides without intersecting the central portion. 
Port means provide access for fluid flow to each straight line path from 
at least one of said sides of said flange. 
The device also includes an extruder bore between each of said pair of 
flanges for enclosing an extruder means. An outer housing has a plurality 
of straight axial channels connected to the straight line paths to conduct 
fluid from one path to a corresponding path in the other of said pair. The 
bore is formed as an axially centered portion aligned with said central 
portion of said flanges. 
Feeder means are used to introduce material into said extruder bore in a 
radial direction. The feeder means includes sealing means in sealing 
contact with said bore and means for mounting said sealing means on said 
housing, whereby no sealing force is applied to said barrel insert. 
Finally, the device includes an inlet and an outlet for transferring fluid 
from selective straight line paths and straight axial channels though the 
port means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, an extruder device generally identified as 10 has a 
drive motor 11, a clutch 13 and a gear system 15 which powers and drives 
the extruder. The particular formulation is fed into the extruder and is 
mixed, reacted and extruded by a pair of extruder screws 17. The extruder 
screws 17 move the formulation through a series of segments 19. 
Segments 19 include a pair of flanges 21 and 23, each being located on one 
end of segment 19. Flange 23, shown in FIG. 2, has a central portion which 
is sized to accommodate a double screw self-wiping extruder. Flange 23 has 
a plurality of straight line paths 27, extending into and out of the 
flange 23 in a plane which is perpendicular to the axis. 
Paths 27 intersect at least three sides of flange 23 and include ports 29 
respectively. Each port 29 provides access to each straight line path 27 
with the corresponding side of the next flange. Having a straight line 
path 27 and having access to the path 27 with a port 29 provides an 
important advantage, whereby cleaning, de-scaling, unplugging and other 
maintenance functions can be performed. This feature provides for a 
segment useful life which is several times greater than other designs. The 
economies are substantial. 
It is possible to provide a fourth side with a port, similar to the other 
ports. This fourth port provides a design in which there are four 
quadrants, so that fluid can flow for heating or cooling through all four 
or through each quadrant separately. 
Channels 25 are positioned adjacent to all sides of the flange 23 are 
aligned radially outward from the center axis. Channels 25 are operably 
connected to flanges 21 and 23 through the extruder barrel housing 31 so 
that they intersect and communicate with paths 27. Channels 25 are 
preferably aligned from a plurality of points on flange 23 to a 
corresponding plurality of points on flange 21. 
Channels 25 not only communicate with paths 27 in each flange 21 and 23 of 
each segment 19, channels 25 can also communicate with channels in 
adjacent segments, so that a wide variety of flow paths are possible. In 
this embodiment, cleaning of the axial channels is also easy, and scale, 
corrosion or sediment can be frequently removed, keeping the heat transfer 
coefficient relatively constant. This, of course, permits more uniform 
production conditions. 
Fluid can be introduced at either the upstream end and flow downstream, or 
the reverse is equally possible. In addition, fluid can be introduced in 
each downstream flange 23 and removed from the corresponding upstream 
flange 21, for example, to permit greater temperature differential between 
the channels 25 and the extruder barrel 31. Flow in the various quadrants 
can be simultaneously counterflowing, or they can all flow in the same 
direction. The flexibility of the present invention is remarkably broad. 
As the fluid travels from flange 23 to flange 21, heat transfer takes place 
with that portion of barrel housing 31 which forms part of segment 19. 
Replacement of the fluid in the next segment will keep the temperature 
differential at a maximum. 
Shown in FIG. 3 is an exploded view of one feed device useful with the 
present invention. FIG. 3 shows the barrel case 31 and the feeder insert 
member 51 [and the standard feeder 53] in an exploded view. Insert 51 is 
placed in hole 45, and the seal is achieved on shoulder 47 by force from 
bolts 57 in holes 59, so that no force is applied to the bore 37. Insert 
51 is seen from along line 3--3 in FIG. 3 as actually being a twin tube 
feeder, because the screws 17 have double flights. 
This feature is particularly important because both wear and sealing 
quality is improved by sealing directly to the bore 37, rather than in 
operating contact with housing 31. At the same time, bolts 57 are mounted 
in holes 59 so that stress from mounting is placed on heavier housing 31, 
not causing stress on the insert 51. 
As is noted in FIG. 4, the insert has two feeder flights so that first and 
second feeder screw paths 61 and 63 provide two holes 65 and 67 for two 
openings 45 in the barrel case 31 so feed can be placed on both flights of 
screw 17 to optimize operation of the system. 
While particular embodiments of the present invention have been illustrated 
and described herein, it is not intended to limit the invention. Changes 
and modifications may be made therein without departing from the following 
claims.