Title of Invention

A STRAND SHAPING PART FOR CONNECTING AN EXTRUDER TO A GRANULATING SYSTEM, PREFERABLE FOR THERMOPLASTIC MATERIAL AND METHOD FOR STARTING THE SAME

Abstract A strand shaping part for connecting an extruder (1) to a granulating system has a number of supply channels (8) that can be flow-connected to the outlet (5) of the extruder (1). These supply channels lead to gear pumps (21) which have a delivery behaviour that is as constant as possible and with which the flow of melt to channels (11) can be blocked during start up. A single channel (11) leads from each gear pump (21) to a strand die (9) that can be formed by holes of a perforated plate (10) which is connected to a perforated plate head (7) . Several gear pumps (21) are driven by a common shaft (24) . The method for starting a granulating system provided with a strand shaping part of the aforementioned type provides that the extruder (1) is first started until a sufficient pressure is built up at the inlet (27) of each gear pump (21). Once this pressure is reached, each gear pump (21) is started again. In an underwater granulating system, the granulating blades (12) are rotationally driven last.
Full Text Strand Shaping Part And Method For Starting The Same
The invention relates to a strand shaping part for connecting an
extruder to a granulating system, preferably for thermoplastic
material, having at least one supply channel that can be
flow-connected to the extruder for the melt, which leads to a gear
pump with which the flow of melt to a channel that leads to a strand
die can be blocked during start up.
Furthermore, the invention relates to a method for starting a
granulating system provided with a strand shaping part of this
type.
Granulating systems offer the advantage of being able to granulate
very low viscous materials, in particular thermoplastic materials,
preferably for recycling purposes. In an underwater granulating
system, the melt delivered by the extruder directly reaches the
granulator housing through which water flows. The cutting tools
which pass the perforated plate and thereby divide the strands
coming out of the holes of the perforated plate which form the
dies into granulated particles also run underwater. On the other
hand, in a conventional strand granulating system, the strands
coming out of the strand dies are left in a water bath in which
the melt soldifies, after which the strands are removed from the
water bath and conveyed to the granulating blades.
To be able to start systems of this type, the melt must be promptly
supplied to the dies to prevent individual dies from freezing as,

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in particular in underwater granulating systems in which the
perforated plate is in contact with water, the melt cools off
quickly. To ensure the aforementioned prompt supply in a strand
shaping part having the known construction described above, the
part carrying out the blocking is formed by a valve which is opened
as soon as the extruder is brought to a full output. Until then,
the melt material conveyed by the extruder is discharged via a
lateral outlet, primarily onto the ground. Aside from the noted
loss in material, the disadvantage is the fact that irregular
throughputs occur at the dies or the holes of the perforated plate,
which results in irregular properties of the granulated material
produced.
A granulating system is known from US 5,723,082 in which a slide
gate is used to block the flow of melt to the dies. This slide
gate can also be omitted, in which case the gear pump has to assume
the function of the slide gate. The flow of melt to the dies can
also be blocked by switching off the gear pump in a construction
according to EP 0 894 594 A2, also in a construction according
to DE 101 17 913 Al. However, in all of these known constructions,
the disadvantage of irregular throughputs on the dies or holes
of the perforated plate can also not be satisfactorily overcome.
The object of the invention is to avoid these disadvantages and
to improve a construction of the aforementioned type in such a
way that at least an almost uniform throughput is ensured at all
dies. The invention solves this object in that several gear pumps
which each have the same delivery behaviour are driven by a common
shaft, wherein a channel from each gear pump leads to a strand

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die. Therefore, each gear pump is connected by a single channel
with the strand die allocated to it. In this way, it is ensured
that each gear pump doses the flow of melt to the die allocated
to it. Since the gear pumps each have the same delivery behaviour
and are driven by the common shaft, this means that each strand
die supplied by the respective gear pump is uniformly supplied
with a volume of melt per unit of time. Thus, uniform conditions
set in for all holes or strand dies, so that a uniform quality
of the granulated material produced is ensured. The dimensions
of the granulated material are then in a very narrow tolerance
zone.
Furthermore, the advantage is offered that, in addition, every
gear pump mixes the melt supplied to it by the extruder, so that
a further uniformity of the quality of the melt is obtained.
Finally, the advantage is given that, when the gear pump is at
a standstill, a preliminary pressure can be built up at the entrance
of the gear pump by means of the extruder. If the gear pump is
not rotationally driven until said preliminary pressure has been
reached, the full flow of mass sets in immediately in the respective
channel leading to the die, as a result of which it is prevented
that these channels freeze.
To safeguard the advantage that no varying conditions occur at
the die outlets, it is advantageous if, within the scope of an
embodiment of the invention, each gear pump of the strand die in
question is arranged so as to be adjacent, so that the length of
the channels leading from the gear pump outlets to the dies is

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short. In contrast thereto, for the most part, there are large
channel lengths between the shutoff valve or the gear pump and
the strand dies or the holes of the perforated plate in the known
constructions, which results in the noted difficulties. This
channel length, which is kept short in accordance with the
invention, can be easily realized structurally in that the strand
dies are provided on a die carrier which forms a housing for the
gear pump. In this case, it is not necessary to form the strand
dies from separate components, of course, the die carrier can also
be a perforated plate head, whereby the strand dies are formed
by holes of a perforated plate fastened to it.
Moreover, the use of gear pumps offers the advantage that it is
possible to be able to set, optionally, the volume flow by changing
the drive of the gear pumps, perhaps differently for individual
pumps of several gear pumps, so that melt is discharged uniformly
everywhere from the holes.
The method according to the invention for starting a granulating
system which is provided with a strand shaping part according to
the invention and supplied with melt by an extruder, is
characterized in that the extruder is first driven until a
sufficient pressure is built up at the entrance of each gear pump,
and that each gear pump is not driven from its thusfar stillstand
state until this pressure has been attained, whereby, in an
underwater granulating system, the granulating blades are
rotationally driven last. This method ensures the aforementioned
avoidance of the melt freezing in the channels leading to the strand
dies or holes of the perforated plate and ensures the uniform
quality of the granulated material cut from the individual strands.

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Examples of embodiments of a strand shaping part according to the
invention are schematically illustrated in the drawings. Figs.
1 and 2 show the use of the invention on a strand granulating system,
whereby Fig. 1 is a section along the line I - I of Fig. 2 and
Fig. 2 is a section along the line II - II of Fig. 1. Figs. 3
to 5 show the application of the invention to an underwater
granulating system, wherein Fig. 3 shows a longitudinal section
through the system, while Fig. 4 is a section along the line IV
- IV of Fig. 3 and Fig. 5 a section along the line V - V of Fig.
3 .
The strand granulating system shown in Figs. 1 and 2 is supplied
by an extruder with the mass to be granulated, in particular, this
mass is formed by thermoplastic material which is to be granulated
for recycling purposes. The extruder has a worm-gear housing in
which a worm driven rotationally about its axis is mounted. The
extruder conveys the plasticized material in direction of arrow
4 into an outlet of the worm-gear housing to which the inlet 6
of a die carrier 30 is tightly attached. From this inlet 6, several
supply channels 8 convey the melt to the channels 11 which lead
to the strand dies 9 fastened to the die carrier 30.
To improve the starting conditions and to ensure uniform quality
properties of the granulated particles cut off, each supply channel
8 leads to a gear pump 21 situated in the die carrier 30, said
gear pump having a constant delivery bvehaviour for the material
conveyed to it for each specific number of revolutions. The
embodiment shown has four gear pumps 21 and, thus, four supply

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channels 8 and four channels 11. The two gears 22 of each gear
pump 21 are rotationally driven in direction of arrow 23. For
this purpose, each gear 22 of each gear pump 21 is mounted so as
to be secured against rotation on a shaft 24 (Fig. 2) which is
driven by a motor 25. The other gear 25 of the respective gear
pump 21 is taken along by the actuated gear via the gearing. The
gear pumps are driven by a common shaft 24.
A single channel 11 is connected to the outlet 26 of each gear
pump 21, as Figs. 1 and 2 show. This channel 11 leads from the
outlet of the respective gear pump 21 to a strand die 9 which is
inserted in the die carrier 3 0 which forms a housing for the gear
pump 21.
The outlet of each strand die 9 is directed downward, so that the
extruded melt strand 31 coming out of it falls into a strand cooling
bath 32 which is filled with water 33. The solidified strands
31 are again removed from this strand cooling bath 32 and conveyed
to a granulator 34 (only shown schematically) from which the cut
granulated particles fall downward in direction of arrow 35.
As Figs. 1 and 2 show, the gear pumps 32 are arranged relatively
close to the dies 9. The advantage of this is that the channels
11 leading from the outlets of the gear pumps 21 to the dies 9
are short, which substantially contributes to the fact that the
melt in these channels 11 is prevented from freezing.
As Fig. 2 shows, the gears 22 of each gear pump 21 are mounted
in bores 28 of the perforated plate head 7 and held in the respective

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axial position in the bore 28 by bushings 29. The shafts 24 pass
through these bushings or engage in them. After the shafts have
been detached from the motors 25, the gears 22, together with the
bushings, can be pulled out of the bores 2 8 or reinserted into
the bores 28 in the opposite direction.
As Figs. 3 to 5 show, the invention can of course also be applied
to underwater granulating systems. As Fig. 3 shows, a system of
this type is supplied by an extruder 1 with the mass to be granulated.
The extruder 1 has a worm-gear housing 2 in which a worm 3 is
mounted which is rotationally driven about its axis. The extruder
conveys the plasticized material in direction of arrow 4 into an
outlet 5 of the worm-gear housing 2 to which the inlet 6 of a
perforated plate head 7 forming a die carrier 3 0 is tightly
connected. From this inlet 6, several supply channels 8 convey
the melt to channels 11 which lead to the holes forming the strand
dies 9 of a perforated plate 10 fastened to the perforated plate
head 7. Granulating blades 12 pass over these holes, said
granulating blades 12 being fastened on a star-shaped blade carrier
13 which is rotationally driven by a motor 15 via a shaft 14, so
that the granulating blades 12 divide the strands exiting the holes
into granulated material. The granulating blades 12, the blade
carrier 13 and the shaft 14 are situated inside a granulating
housing 16 into which water is continuously let in via an inlet
17 in direction of arrow 18, so that the granulating blades 12
and the perforated plate 10 are continuously rinsed by water.
The water runs out of the granulating housing 16 again via an outlet
19 in direction of arrow 20 and thereby takes along the granulated
particles cut off by the granualting blades 12.

- 8 -
Each melt channel 8 leads to several gear pumps 21 which are
arranged in the perforated plate head 7, each gear pump having
a constant delivery behaviour for the material supplied to it for
each specific number of rotations. The embodiment shown has four
gear pumps 21 which are driven in a similar manner and mounted
on drive shafts 24, as was described in association with the
embodiment according to Figs. 1 and 2.
A single channel 11 leads from the outlet 2 6 of each gear pump
21 to a strand die 9 formed by a hole on the perforated plate 10
(Fig. 5). As can be seen, these strand dies 9 are distributed
over the surface of the perforated plate 10, a gear pump 21 being
allocated to each of these holes 9. In the embodiment shown, four
strand die holes 9 are provided on the perforated plate 10,
practical embodiments may have one to twelve holes 9 and,
accordingly, a corresponding number of gear pumps 21. As a result,
the necessary material flow can be ensured by varying the number
of gear pumps 21 and strand dies 9. As Fig. 3 shows, in this
embodiment also, the gear pumps 21 are arranged relatively close
to the holes 9 of the perforated plate 10, so that the channels
11 leading from the outlets 26 of the gear pumps 21 to the holes
9 of the perforated plate 10 are short, which results in the already
noted advantage that the melt in the channels 11 is prevented from
freezing.
When starting a system of this type, whether it be an underwater
granulating system or a strand granulating system, one proceeds
in such a way that the gear pumps 21 are first stopped and,

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consequently, the material flow between the extruder 1 and the
dies 9 is completely blocked. The extruder 1 is then started and
conveys the plastic material to be processed into the inlet 6 of
the die carrier 3 0 which simultaneously forms a housing for the
gear pumps 21. As a result, a pressure in the plastic material
supplied builds up at the inlet 27 of each gear pump 21. As soon
as this pressure has reached a preset value, which can be monitored
by pressure sensors (not shown), all gear pumps 21 are promptly
started and thus convey the plastic material supplied to them with
constant delivery behaviour into the channels 11 to the dies/dies
9.
Throughput capacities of 20 to 60 kg per hour and per hole of the
perforated plate can be obtained with a granulating system designed
according to the invention, which signifies an increase of the
maximum throughput capacity in comparison to known constructions.

- 10 -
Patent Claims
A strand shaping part for connecting an extruder (1) to a
granulating system, preferably for thermoplastic material,
having at least one supply channel (8) for the melt that can
be flow-connected with the extruder (1) which leads to a gear
pump (21) with which the flow of melt to a channel (11) , which
leads to a strand die (9), can be blocked during start up,
characterized in that several gear pumps (21) that each have
the same delivery behaviour are driven by a common shaft (24) ,
wherein a channel (11) leads from each gear pump (21) to a
strand die (9).
The strand shaping part according to claim 1, characterized
in that each gear pump (21) is arranged adjacent to the
respective strand die (9) , so that the length of the channels
(11) is as short as possible.
The strand shaping part according to claim 1 or 2,
characterized in that the strand dies (9) are provided on
a die carrier (3 0) which forms a housing for the gear pumps
(21) .
The strand shaping part according to claim 3, characterized
in that the die carrier (30) is a perforated plate head and
the strand dies (9) are formed by holes of a perforated plate
fastened to it.

- 11 -
The strand shaping part according to claim 3 or 4,
characterized in that the gears (22) of each gear pump (21)
are situated in bores (28) of the die carrier (30) and are
each secured in their axial position in the respective bore
(2 8) by means of at least one bushing (29) , wherein at least
one bushing (29) is passed through by a drive shaft (24) for
the gears (22) .
A method for starting a granulating system provided with a
strand shaping part according to any one of the claims 1 to
5 which is supplied with melt by an extruder (1),
characterized in that the extruder (1) is first driven until
a sufficient pressure is built up at the inlet (27) of each
gear pump (21) and that each gear pump (21) is not driven
from its stillstand state until this pressure has been
attained, whereby, in an underwater granulating system, the
granulating blades (12) are rotationally driven last.

A strand shaping part for connecting an extruder (1) to a
granulating system has a number of supply channels (8) that can
be flow-connected to the outlet (5) of the extruder (1). These
supply channels lead to gear pumps (21) which have a delivery
behaviour that is as constant as possible and with which the flow
of melt to channels (11) can be blocked during start up. A single
channel (11) leads from each gear pump (21) to a strand die (9)
that can be formed by holes of a perforated plate (10) which is
connected to a perforated plate head (7) . Several gear pumps (21)
are driven by a common shaft (24) .
The method for starting a granulating system provided with a strand
shaping part of the aforementioned type provides that the extruder
(1) is first started until a sufficient pressure is built up at
the inlet (27) of each gear pump (21). Once this pressure is reached,
each gear pump (21) is started again. In an underwater granulating
system, the granulating blades (12) are rotationally driven last.

Documents:

02000-kolnp-2007-abstract.pdf

02000-kolnp-2007-claims.pdf

02000-kolnp-2007-correspondence others 1.1.pdf

02000-kolnp-2007-correspondence others 1.2.pdf

02000-kolnp-2007-correspondence others 1.3.pdf

02000-kolnp-2007-correspondence others.pdf

02000-kolnp-2007-description complete.pdf

02000-kolnp-2007-drawings.pdf

02000-kolnp-2007-form 1.pdf

02000-kolnp-2007-form 18.pdf

02000-kolnp-2007-form 2.pdf

02000-kolnp-2007-form 3.pdf

02000-kolnp-2007-form 5.pdf

02000-kolnp-2007-international publication.pdf

02000-kolnp-2007-international search report.pdf

02000-kolnp-2007-others pct form.pdf

02000-kolnp-2007-others.pdf

02000-kolnp-2007-pct request form.pdf

02000-kolnp-2007-priority document 1.1.pdf

02000-kolnp-2007-priority document.pdf

2000-KOLNP-2007-(02-01-2012)-CORRESPONDENCE.pdf

2000-KOLNP-2007-(02-01-2012)-PA-CERTIFIED COPIES.pdf

2000-kolnp-2007-abstract 1.1.pdf

2000-KOLNP-2007-ABSTRACT.pdf

2000-KOLNP-2007-AMANDED CLAIMS 1.1.pdf

2000-KOLNP-2007-AMANDED CLAIMS.pdf

2000-KOLNP-2007-AMANDED PAGES OF SPECIFICATION.pdf

2000-KOLNP-2007-CANCELLED PAGES.pdf

2000-KOLNP-2007-CORRESPONDENCE 1.1.pdf

2000-KOLNP-2007-CORRESPONDENCE OTHERS 1.4.pdf

2000-KOLNP-2007-CORRESPONDENCE OTHERS-1.4.pdf

2000-kolnp-2007-correspondence.pdf

2000-KOLNP-2007-DESCRIPTION (COMPLETE) 1.1.pdf

2000-KOLNP-2007-DESCRIPTION (COMPLETE).pdf

2000-KOLNP-2007-DRAWINGS 1.1.pdf

2000-KOLNP-2007-DRAWINGS.pdf

2000-kolnp-2007-examination report.pdf

2000-KOLNP-2007-FORM 1 1.1.pdf

2000-KOLNP-2007-FORM 1.pdf

2000-kolnp-2007-form 18.pdf

2000-KOLNP-2007-FORM 2 1.1.pdf

2000-KOLNP-2007-FORM 2.pdf

2000-kolnp-2007-form 26.pdf

2000-KOLNP-2007-FORM 3 1.1.pdf

2000-kolnp-2007-form 3.2.pdf

2000-KOLNP-2007-FORM 3.pdf

2000-kolnp-2007-form 5.1.pdf

2000-KOLNP-2007-FORM 5.pdf

2000-KOLNP-2007-FORM-27.pdf

2000-kolnp-2007-granted-abstract.pdf

2000-kolnp-2007-granted-claims.pdf

2000-kolnp-2007-granted-description (complete).pdf

2000-kolnp-2007-granted-drawings.pdf

2000-kolnp-2007-granted-form 1.pdf

2000-kolnp-2007-granted-form 2.pdf

2000-kolnp-2007-granted-specification.pdf

2000-KOLNP-2007-INTERNATIONAL EXM REPORT.pdf

2000-KOLNP-2007-OTHERS 1.1.pdf

2000-kolnp-2007-others.pdf

2000-KOLNP-2007-PA.pdf

2000-KOLNP-2007-PETITION UNDER RULE 137.pdf

2000-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

2000-kolnp-2007-reply to examination report1.1.pdf

abstract-02000-kolnp-2007.jpg


Patent Number 248189
Indian Patent Application Number 2000/KOLNP/2007
PG Journal Number 26/2011
Publication Date 01-Jul-2011
Grant Date 27-Jun-2011
Date of Filing 04-Jun-2007
Name of Patentee EREMA ENGINEERING RECYCLING MASCHINEN UND ANLAGEN GESELLSCHAFT M.B.H.
Applicant Address UNTERFELDSTRASSE 3, FREINDORF, A-4052 ANSFELDEN
Inventors:
# Inventor's Name Inventor's Address
1 HELMUT BACHER SCHMIDBERGERWEG 6, A-4490 ST, FLORIAN
2 GEORG WENDELIN WALDBOTHENWEG 84, A-4033 LINZ
3 HELMUTH SCHULZ HIRSCHGASSE 16/12, A-4020 LINZ
PCT International Classification Number B29B 9/06
PCT International Application Number PCT/AT2006/000013
PCT International Filing date 2006-01-12
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 A 78/2005 2005-01-18 Austria