Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
205~139
NETHOD AND APPARATUS FOR FEEDING POUR~BLE MATERIAL INTO AN
INLET OPENING OF A PROCESSING MACHINE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention refers to a method for feeding pourable
material, preferably granulated material, into an inlet
opening of a processing machine, preferably an extruder for
synthetic material, with a storage container provided with a
conveying means for the filling thereof and with a closable
outlet opening at the bottom, and with an intermediate
storage container supported on a weighing means or provided
with a filling level measuring means, said intermediate
storage container being filled with material in
correspondence with its filling weight or the filling level
and provided with a bottom-side outlet opening leading into
the inlet opening.
Description of Prior Art
The correct and troublefree functioning of machines
processing pourable material often depends on said material
being supplied uniformly, i.e. under a substantially constant
pressure. In principle, an extruder for synthetic material
only then works satisfactorily, when the granulated synthetic
materials and, if necessary, materials added thereto are fed
to the extruder at a constant rate. This can for instance be
ensured by the fact that in the feeding hopper or in an
intermediate storage container corresponding to the feeding
hopper or substituting it, a sufficient amount of material is
constantly maintained which ensures a continuous feeding of
the material into the extruder.
On the basis of Fig. 1 and 2 of the drawings, a known method
as well as a known apparatus will be described in the
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following, by means of which granulated material or any other
pourable material can be fed to an extruder for synthetic
material such that it can be uniformly drawn in. Above the
inlet opening 2 of a part of an extruder 1 (only
schematically shown) a lower intermediate storage container 3
being designed as a proportioning weigher is arranged in a
hanging position. Said lower intermediate storage container
3 is carried by a supporting arm 4 which is connected to the
machine frame in the shown manner and which has an
extensometer 5. Above the lower intermediate storage
container 3 designed as a proportioning weigher there is
arranged a further funnel-shaped upper intermediate storage
container 6 with the bottom outlet 7 thereof being provided
with a slide closing means 8 by which the outlet 7 can be
closed and opened. On the cover of said further upper
intermediate storage container 6 there is arranged a storage
container 9 the cover of which carries an extractor 10. The
funnel-shaped outlet 11 of said storage container 9 can be
closed by a pivotally supported flap 12 provided with a
tension spring 13 acting upon said flap in closing direction.
In its upper part the storage container 9 is provided with a
filling level measuring means 14 detecting the upper filling
limit for the suctioned granulated material in the storage
container 9. The granulated material 15 is supplied to the
storage container 9 via a suction pipe 16.
In Fig. 1 there is shown the condition in which the extractor
10 is turned on and the flap 12 closed so that to the storage
container 9 granulated material is supplied via the suction
pipe 16 up to a filling level height predetermined by the
filling level measuring means 14. When the granulated
material reaches at the filling level measuring means 14, the
extractor 10 is turned off by a switch operated by the
filling level measuring means.
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When the storage container 9 has been filled with granulated
material up to the height predetermined by the filling level
measuring means 14 and when then the extractor is turned off,
the flap 12 is pressed open by the weight of the granulated
material stored in the storage container 9, since the closing
spring 13 is designed to have approximately that strength as
to being able to close the flap when there is no filling
pressure or only a minor filling pressure exerted thereon.
During the filling of the storage container 9 the flap 12 is
kept in its closing position due to the negative pressure
existing in the storage container.
During the filling of the storage container 9 with granulated
material, the slide 8 can be pulled open in dependency on the
filling weight detected by the proportioning weigher so that
the granulated material flows from the further intermediate
storage container 6 into the lower storage container 3. The
slide 8 is again brought into its closing position as soon as
the proportioning weigher detects a sufficient filling amount
in the lower intermediate storage container 3. The command
for pulling the slide 8 open comes from a signal derived from
the extensometer 5.
In Fig. 2 there is shown the condition in which the extractor
10 has been turned off after reaching the filling height
detected by the filling level measuring means 14 and the
storage container 9 is discharged into the upper intermediate
storage container 6 by the fact that the flap 12 is pressed
open due to the weight of the filling load. However, when
the upper intermediate storage container 6 is filled in the
manner according to Fig. 2, the flap 12 can no longer be
closed since it is blocked by the material piled up in the
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upper intermediate storage container. The closing spring 13
can only then move the flap 12 again in its closing position
when the upper intermediate storage container 6 has been dis-
charged into the lower intermediate container 3 after pulling
the slide 8 open so that the flap 12 is no longer blocked by
the piled up material.
In the known apparatus described on the basis of Fig. 1
and 2, the extractor 10 is always turned on when the flap 12
is closed. The filling of the storage container 9 is then
terminated by turning off the extractor 10, when the filling
level has reached the level of the filling level measuring
means 14. Independent of the control of the filling of the
storage container 9, the opening movement and closing movement
of the slide 8 is controlled by the proportioning weigher or
the extensometer S such that the slide 8 is opened when a
lower filling level is reached and closed again when an upper
filling level is detected due to the corresponding weight.
The apparatus explained on the basis of Fig. 1 and 2
does not only have a considerable overall height due to the
arrangement of the three containers one on top of the other,
but due to the two control means being operated independently
of each other for filling and discharging the three containers
it is also of a relatively high technical expenditure.
Summary of the Invention
Therefore it is the ob~ect of the invention to provide
a method and an apparatus which enable a storage container
arrangement of a lower overall height and with a simpler con-
trol.
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According to the invention this problem is solved for a
method of the kind mentioned hereinbefore in that the storage
container is discharged completely or partially in dependency
on the filling ratio of the intermediate storage container
thereinto by opening of its outlet opening, and after closing
the outlet opening, the storage container is again filled up
with granulated material with a predetermined filling ratio.
The method according to the invention enables the constant
supply of material to a processing machine with only one
storage container and one intermediate container, the closing
means of the storage container and the conveying means
filling it only being controlled in dependency on the filling
weight or the filling ratio of the lower intermediate storage
container. In addition, the conveying means filling the
upper storage container are controlled by its upper filling
level, which provides an upper threshold for stopping the
converging means. Thus, the apparatus operating according to
the inventive method consists of only two containers and one
control means controlling the filling as well as the opening
action for discharging and the closing of the upper storage
container.
The filling ratio of the intermediate storage container is
the filling weight relating to the upper and lower
thresholds. When the weight reaches the lower threshold, the
gate is opened when the filling weight reaches the upper
threshold, the gate is closed.
An apparatus for carrying out the method according to the
invention is characterized according to the invention in that
the closing means of the outlet opening are provided with a
switch means turning on the conveying means during or after
the closing of the outlet opening, and that the weighing or
filling level measuring means generates a signal after
.
205~3139
reaching the predetermined filling ratio, said signal turning
off the conveying means.
The conveying means filling the storage container with
material can be a suction conveying means.
Advantageously, a conveying pipe leads into the upper portion
of the portion of the storage container, the storage
container being closed by a cover provided with an extractor
fan.
In an alternative embodiment, the filling levels may be used
to trigger opening and closing of the gate, but the filling
weight is preferred.
The intermediate storage container can be carried by a
supporting arm connected with the machine frame, which can be
provided with at least one extensometer for the detection of
the filling weight. Thus the intermediate storage container
has the function of a proportioning weigher, the closing
means of the storage container being opened and closed in
correspondence with the filling weight by signals generated
by the proportioning weigher.
one embodiment of the invention will now be described in the
following with reference to Fig. 3 of the drawing.
Detailed DescriPtion of Preferred Embodiment
The structure and the mounting of the lower intermediate
container 3' correspond to the structure and the mounting of
the lower intermediate container 3 according to Fig. 1 and 2.
The lower intermediate container 3' has a funnel-like form in
its lower section and is provided with an outlet leading into
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the inlet opening 2' of the extruder 1'. The lower
intermediate container 3' is connected with the machine frame
by a supporting arm 4' provided with at least one
extensometer 5', so that it shows the function of a
proportioning weigher.
Above the lower intermediate container 3' there is arranged
an upper storage container 9' of greater volume than the
lower intermediate container 3' and with its lower outlet 7'
being closable by a slide or gate 8'. Into the upper section
of the storage container 9' there leads a conveying pipe
designed as a suction pipe 16'. The cover of the storage
container 9' is provided with an extractor lo' by the
operation of which granulated material can be suctioned in
through the suction pipe 16'. The storage container 9' is
provided with a filling level measuring means 14' which
detects the maximum admissible filling level height in the
storage container 9'.
In the operating state as shown in Fig. 3, the slide 8' is
opened so that granulated material can flow into the lower
intermediate container 3' constituting a proportioning
weigher. By opening the slide 8' there is simultaneously
produced a signal which prevents the extractor 10' from being
turned on. The slide 8' is closed as soon as a signal
derived from the extensometer 5' indicates that in the lower ^~
intermediate storage container 3' there is a sufficient
weight of material or that the filling ratio of the lower
intermediate storage container 3' is not increasing. On
closing the slide 8' there is directly produced a signal
which turns on the extractor 10'. The extractor 10' remains
turned on until by the suction pipe 16' such an amount of
granulated material has been suctioned into the intermediate
storage container 9' that the filling level measuring means
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14' is activated by the increasing filling level. As soon as
the filling level measuring means 14' detects the upper
filling level in the container 9', the extractor 10' is
turned off. Discharging and filling of the lower
intermediate storage container 3' and of the storage
container 9' is carried out during operation in the described
manner.
In an alternative embodiment the closing of the slide 8' can
be triggered by the filling level in the lower intermediate
container 3'.
A further inventive embodiment is the subject of independent
claim 6.
In contrast to the apparatus described on the basis of Fig. 1
and 2, the apparatus according to the invention shows the
advantage that the overall height of the filling apparatus is
reduced by approximately 1/3 and that the control of the
apparatus is considerably simplified.
