Device for charging injection molding and extruding machines and having a funnel provided with pins passing through clearances in a feed worm

The problem of insufficient friction along the wall of a rotating funnel feeding viscous material to an extruder or injection molding machine so that the material sweeps past the conveying screw and prevents the conveying screw from continuously feeding that mass to the outlet of the funnel, is solved by providing pins which project inwardly from the rotating funnel wall and engage in interruptions in the flight of the conveying screw. The funnel wall can also be provided with pockets or grooves.

FIELD OF THE INVENTION 
The present invention relates to a device for charging with a plastifiable 
or plastic mass, generally a viscous mass or a mass of flowable powder or 
comminuted materials or mixtures thereof, injection molding machines and 
extruders. More particularly, the invention relates to an apparatus for 
charging injection molding and extruder units having a feedworm in the 
case of an extruder or a piston feed chamber in the case of an injection 
molding machine, with viscous materials, especially glass-fiber charged 
plastics, e.g. polyesters and polypropylene, utilizing a filling funnel 
and a worm which lies along an inner wall of that funnel and is rotatable 
so that its flight will advance the flowable mass from the wide mouth of 
the funnel toward the narrow outlet communicating with the extruder or 
injection molder chamber. 
BACKGROUND OF THE INVENTION 
An apparatus of the type described is illustrated, for example, in the 
commonly owned German Patent 37 12 828 and German Open Application DE-OS 
40 24 994 A1. In both of these systems, a funnel is provided which can be 
rotated about the axis of the frustocone, which axis forms an acute angle 
with the axis of the conveyor screw lying along the wall of the funnel and 
forcing the mass into a passage communicating with an injection molding 
machine or extruder unit. 
In terms of prior art, mention can also be made of German Patent Document 
137 813 which describes a meat chopper having a worm whose flight is 
interrupted to cooperate with pins projecting toward the worm in the 
regions of such interruption. The interaction of the worm and the pins 
serves to comminute the meat. A screw vent is described in U.S. Pat. No. 
4,117,548 which has a pin extending into a region in which a flight is 
interrupted and in German Published Application DE-AS 1 003 947, the cross 
section of an extruder worm is serrated or fluted to promote the shearing 
action. Finally, mention may be made of DE-AS 1 529 803 which provides a 
pocket in the worm chamber of an extruder also to cooperate with the worm 
in the advance of the flowable mass therealong. 
However, in systems of the type described in German Patent DE 37 12 828 and 
DE-OS 40 24 994, in which the wall of the frustoconical funnel is 
relatively smooth and, as is customary, may be chromium coated to reduce 
wear, with long operating intervals with materials which are relatively 
abrasive, for example, recycled plastics, fillers, glass fibers, ceramics 
and the like, the materials processed additionally smooth and polish the 
inner surface so that it tends to lose all of its original surface 
roughness. 
As a consequence, material can slip past the feeder conveyor so that the 
conveyor, while continuously operating, does not continuously feed the 
mass and hence the output of the apparatus is reduced. 
When an attempt was made to solve this problem by providing worms or screws 
with teeth, the improvement was minimal. 
OBJECTS OF THE INVENTION 
It is the principal object of the present invention to provide an improved 
apparatus of the type described, i.e. a feeder for an injection molding 
machine or extruder which will increase the feeding rate to the apparatus 
and reliably insure continuity of feed of the material introduced into the 
funnel. 
Another object of this invention is to provide a device or apparatus, i.e. 
a feeder for an injection molding machine or extruder, which will overcome 
the drawbacks of earlier devices for this purpose. 
SUMMARY OF THE INVENTION 
These objects and others which will become more readily apparent 
hereinafter are attained, in accordance with the invention by providing 
the inner surface of the frustoconical rotating funnel with at least one 
formation, i.e. projections and/or recesses, and to provide the worm or 
screw with a recess or cutout to allow free passage of the projections on 
the rotating frustoconical funnel wall. 
The feeder of the invention is intended for a shaping machine for a viscous 
mass, i.e. an injection molding machine or an extruder, and can thus 
comprise: 
a frustoconical filling funnel rotatable about an axis and having a wide 
mouth at one end and a narrow outlet at an opposite end communicating with 
the receiving chamber of the shaping machine; 
a rotatable conveyor screw extending along an inner wall of the funnel 
parallel to a generatrix thereof and formed with a screw flight for 
displacing the viscous plastic mass toward the outlet; and 
at least one formation on the inner wall forming a discontinuity in a 
rectilinear path therealong between the mouth and the outlet and in a 
region of the flight, the screw being provided with a recess to clear any 
portion of the formation projecting toward the screw upon rotation of the 
formation with the funnel past the screw. 
The feeder supplies a metering worm in the case of an extruder or a piston 
prechamber in the case of a piston type injection-molding machine with a 
viscous material, especially a glass fiber charged plastic like a 
polyester or polypropylene. 
With the apparatus, relatively thick, high filler sheet molding compound 
(SMC) can be processed and in the case of bulk molding (BMC) masses, the 
feed rate can be doubled or the time in which a given amount of material 
is supplied to the extruder or injection molding machine through a given 
apparatus can be reduced by half. 
Thermoplastic scrap materials and recycled plastics can also be processed 
without difficulty with the apparatus of the present invention with a high 
degree of reliability. The apparatus has also been found to be effective 
with thermoset resins, for example, phenolic resins and to be effective 
with rubber scrap, for example, scrap tires. 
According to a feature of the invention, the formations include at least 
one pin projecting inwardly from the inner wall and a multiplicity of such 
pins, the recess in the conveyor screw being an interruption in the worm 
flight for clearing the pin. 
When a multiplicity of pins are provided, they are provided in one or more 
rows along the inner wall. Means can be provided for adjusting the height 
to which the pin extends in the funnel. Furthermore, the discontinuities 
in the wall can include pockets or grooves formed therein.

SPECIFIC DESCRIPTION 
FIG. 1 shows an extruder 8 forming part of an injection molding machine 21 
whose piston 20 can displace the worm 8a of the extruder in the direction 
of the arrow 22. The worm 8a is the feed worm for the plastifying portion 
of the extruder which communicates with an injection molding mold in the 
usual manner. The piston 20 can be driven by a motor 23 to rotate the worm 
or screw 8a in the usual manner. 
Above the machine 8, 21, a filling funnel 2 is provided, the funnel being 
rotated by a drive 3 about an axis A inclined at an acute angle to the 
axis of the screw 8. Along a generatrix of the inner wall 4 of the funnel 
2 a conveyor worm or screw 6 is driven by a motor 5 and extends through 
the funnel from its wide mouth to its narrow outlet end, feeding the mass 
to an outlet connected by a pipe section 7 in the form of an elbow to the 
metering screw 8a of the extruder. 
The inner surface 4 of the funnel is provided with two rows of pins 9 which 
project inwardly from the inner wall 2 and sweep through recesses 10 
formed in the screw 6 as interruptions of the flight. FIG. 2 shows that 
the pin 9 has a screwthread 11 which is clamped by the nut 12 to the 
funnel 2. The screw can be adjusted in the funnel wall and locked by the 
nut 12. 
In the embodiment of FIG. 3, the pin 9 is formed with a sleeve 13 threaded 
onto the screw 11 which can be threaded into the wall of the funnel and 
locked by the nut 12 and the lock washer 14, the sleeve 13 being adjusted 
on the screw 11 and held in place by a set screw 15. 
The inner wall 4 of the funnel is provided not only with the pins 9 
previously described but also with grooves or pockets 16 which likewise 
form discontinuities in the rectilinear path along the wall of the funnel 
from its wide mouth to its narrow inlet.