Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
The invention relates to an apparatus for separating a contaminated
portion of bulk ma~erial from a flow of Plowable bulk material. The
contaminations may include particularly metal particles which do
not contaminate the entire bulk material, but only a portion or
portions. The removal is to ~e accomplished while the flowable
bulk material travels through a movable bulk material flow pipe,
also referred to as a drop pipe arranged for cooperation with a
sensor or detector for the contaminations. An output signal from
the detector controls a drive for moving the drop pipe.
DESCRIPTION OF ~HE PRIOR ART
Flowable products, such as granular synthetic material used for
injection molding p~rposes, may contain undesirable contaminations,
especially metallic contaminations which can cause substantial
damage to the production machinery, thereby leading to undesirable
and costly shut-downs.
In order to avoid the foregoing problems, there are metal separat-
ing devices available in the art which use detectors operating
with inductive or magnetic means for the sensing of the contamina-
~0 tions. These sensors provide a signal in response to the presenceof metallic contaminations in a bulk material flow travelling freely
downwardly in a drop chute or the like. The detector controls
the movement of a flap hinged ln position below the drop chute.
It is also known to provide a fle~ible drop pipe or chuke which
is moved from a normal position into a discharge position in response
to a control signal from the sensor or detector.
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1 Since the sensing of the presence of ~ contamination and the removal
of the contaminated portion must take place during the free fall
motion of the flowable bulk material in the drop chute or pipe,
a substan~ial vertical spacing is required between the detector
and the discharge mechanism for the contaminated material in order
to obtain sufficient time for the proper removal of the contaminated
material. Such time is required due to the electrical and mechan-
ical response characteristics which involve a certain delay between
the sensing and the subsequent material removal. The mentioned
spacing in turn results in a substantial structural height of con-
ventional devices so that their use in connectlon with production
machinery such as injection molding machines is restricted having
regard to the available space or rather height of the room in
which the machinery is to be installed. Further, the above men-
tioned conventional separators cannot be used in connection with
devices in which a column of bulk material is stationary, except
when a portion of bulk material slides down in response to the
use of a respective portion.
OBJECTS OF THE INVENTION
In view of the foregoing it is the aim of the invention to
achieve the following objects singly or in combination:
to provide an apparatus of the type described above
which is improved in that it has a substantially smaller struc-
tural height without impairing its ability to Punction for the
intended purpoYe;
,
1 to construct such a separator short enough in the
vertical direction that it may be directly mounted on top of a
production machine, for example, an injection molding automat,
and
to use detectors capable of sensing the presence of
contaminations other than metal parts, such as glass, rocks, or
the like.
SUMMARY OF THE INVENTION
The apparatus of the invention is characterized in that flow
retarding means such as baffle plates or flow direction changing
elements are installed in the flow or drop pipe for the flowable
bulk material. The drive member is connected with the flow or
drop pipe for moving the flow or drop pipe from a normal position
to a contamination discharge position and back again in response
to a detector control signal. Additionally, means are provided
which close the inlet of the apparatus into the drop or flow pipe
when the latter is in the contamination discharge position. The
closure means are located above the baffle plates or deflection
members.
The invention makes sure that the free fall of the flowable bulk
material is retarded after the bulk material has passed through
the contamination detector~ Thus, the structural height of such
an apparatus can be surprisingly reduced a~ compared to devices
of the prior art.
Another advantage of the in~ention is seen in that the present
apparatus can even be used in connection with stationary
flowable bulk material columns because during the discharge of
a contaminated portion, material cannot pass into a space behind
the closure member, ~or example, in the form of a slide yate to
thereby impede the return movement of the slide gate.
In summary, therefore, the present invenkion may be considered
as providing an appara~us for separating a contaminated portion
of bulk material from a flow of flowable bulk material,
comprising a housing having an inlet and first and second
outlets, a casing movably arranged in said housing, flow pipe
means arranged substantially vertically in said casing and
forming part of a flow passage for normally passing
uncontaminated bulk material from said inlet to one of said
outlets when said flow pipe means interconnect said inlet with
said one outlet, drive means connected to said casing for moving
said flow pipe means between a normal position in which said
flow pipe means can discharge uncontaminated bulk material
through said said one outlet and a further position in which
said flow pipe means can discharge contaminated bulk material
through the other of said outlets, metal detector means arranged
for cooperation with said flow pipe means for providing a drive
control signal in response to the presence of any metal in said
bulk material flowing through said flow pipe means, said flow
pipe means being surrounded by said metal detector means and
operatively connected with said casing, said drive means
comprising a drive member operatively connected to said movable
casing, electronic control means connected to receive said drive
control signal for controlling the operation of said drive
member in response to said drive control signal, said housing
comprising guide means ~or guiding said casing together with
said flow pipe means and said metal detector means when said
casing is driven by said drive means between said normal
position and said further position, a pipe section for storing
a quantity of bulk material in said pipe section, said pipe
section being connected below said casing for communicating
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with said flow pipe meang through ~aid one outlet when said
flow pipe means are in said normal position, means located in
said flow pipe means below said metal detector means for slowing
down a flow of bulk material through said ~low pipe means so
that said metal detector means and sai~ drive means can become
effective if any metal is present in said bulk mat~rial passing
through said flow pipe means, and gate means connected to said
casing to move with the casing for closing said inlet in said
housing when said flow pipe means with its casing is in said
further position and for discharging a contaminated portion of
bulk material through said other outlet.
BRIEF DESCRIPTION OF THE D~AWINGS
In order that the invention may be clearly understood, it will
now be described, by way of example, with reference to the
accompanying drawings, wherein:
Fig. 1 is a somewhat schematic side ~iew of the
apparatus according to the invention;
Fig. 2 is a sectional view through the movable flow or
drop pipe according to the invention using baffle plates for
retarding the free fall of the bulk material;
Fig. 3 is a sectional view similar to that of Fig. 2,
but showing a modified flow pipe with a knee pipe section for
retarding the material flow; and
Fig. 4 is a block diagram illustrating the control
mechanism for the movement of the flow pipe back and forth
between its normal position and its contamination discharge
position.
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12658/LCM:sd
1 DETAILED D~SCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND
OF THE BEST MODE OF THE INVENTION
The present apparatus separates con~aminated portions of flowahle
bulk material from the flow of such bulk material. Especially
magnetic and non-magnetic metal particles are detected and that
portion containing these particles is removed. For this purpose
the separating mechanism 1 comprises a flow or drop pipe section 2
in the form of a block or casing having a passage 2' therethrough.
~he casing 2 is arranged in a housing 9 having an inlet 17 connected
to a funnel or hopper 28 for introducing the flowable bulk material
as indicated by the arrow A. The housing 9 has two outlets 17'
and 7. The outlet 17' registers with the inlet 17 through the
flow or drop passage 2' for discharging uncontaminated bulk material
in the direction of the arrow B. The second outlet 7 is located
to the left of the first outlet 17' and serves for discharging
contaminated bulk material in the direction of the arrow C when
the casing 2 and thus the flow or drop passage 2' has been moved in
the direction of the arrow D to the left in Fig. 1, as will be
described below.
The casing 2 contains a sensor or detector 12, baffle plates 3
and 4 which are slanted relative to the vertical flow direction,
drive means such as a piston cylinder device 13, and an electronic
signal processing and evaluating circuit shown in block form in
Fig. 4 for providing a control signal for the piston cylinder
device 13 in response to the detection of a contamination passing
through the detector 12. The housing 9 compriseR two guide rails
10 on which the casing 2 i slidably mounted for a horizontal back
and forth movement. ~hus, the gulde rail~ 10 engage guide grooves 10'
) 8 ~ 8 6
1 in the casing 2 as best seen in Eig. 2. The piston cylinder
device 13 may be operated pneumatically or hydraulically through
a respective source of pressure not shown. The supply of fluid
under pressure to one or the other end of the piston cylinder de-
vice 13 is controlled by an electro-magnetic valve shown in Fig. 4.
A ring or collar 11, for example of synthetic material t surrounds
the lower end of the funnel 28 to properly guide flowable bulk
material into a drop pipe 5 in the casing 2 surrounded by the
detector 12. The drop pipe 5 extends vertically and forms part
of the flow passage 2', the lat~er extending entirely thruugh the
casing 2. A vertical pipe section 15 is connected to the first
outlet 17' and may serve to store a portion of bulk material that
has passed through the flow or drop passage 2'. The lower end of
the pipe section 15 may be directly connected to a production
machine, not shown, for example, by means of a flange 6.
The lower open end 2" of the casing 2 will come to register with
the second outlet 7 when the piston cylinder device 13 has moved
the casing 2 into the left-hand position in the housing 9 of Fig. 1.
In order to stop the further flow of material when the casing 2
is in the left-hand position in Fig. 1, a slide gate member 8
is connected to move with the casing 2 to thereby close the lower
end of the funnell80r inlet 17. The slide member 8 is so dimensioned
that it properly closes the inlet 17 when the casing is in the
left-hand position, but opens the inlet when the casing 2 is in
the right-hand position as shown in Fig. 1
Fig. 2 shows the separating apparatus 1 in more detail. The right-
hand guide rail 10 of the housing 9 i9 provided with an elongated
slot 19 also seen in Fig. 1 for the insertion oE an electrical
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1 conductor cable into a plug-in socket 18 for connecting the
detector 12 with its sensor coils 14 to the circuit of Fig. 4.
A flexible cable is used so that the cable may move back and forth
with the casing 2. The baffle plates 3 and 4 are vertically spaced
~rom each other and arranged approximately diametrically opposite
each oth~r with a slant relative to the vertical flow direction
of the bulk material. The plates 3 and 4 slant in opposite direc-
tions downwardly just sufficient so as to retard the flow of
material for a time of sufficient duration for compensating any
response delays. Pre~erably, the lo~er ends of the baffle plates
slightly overlap each other to prevent a free fall of bulk material.
Thus, the bulk material first impinges on the baffle plate 3 and
then on the baffle plate 4.
The detector 12 comprises, for example, induction coils 14 sur-
rounding on the one hand the drop or flow pipe 5 and surrounded
on the other hand by an electrical and magnetic screen 16. The
coil 14 comprises a coupling coil section and an oscillating cir-
cuit coil section connected to the circuit shown in Fig. 4. ~he
screen 16 may be provided in the form of a focussing ring. Metallic
particles travelling through the flow or drop pipe 5 cause a change
in the output voltage of the coil portion forming part of the
oscillating circuit. As a result, the oscillator output voltage
is also changed and the output signal passes through a differentiating
circuit and through an amplifier circuit including a threshold
compensating circuit component for evaluating the signal and thereby
controlling a relay. The relay in turn activates the control valve
for the drive piston cylinder davice 13. ~hus, the detector, or
rather its coils 14, are 80 arranged that the metallic particles
passing through the high requency vibration field of these coils
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1 control the above mentioned relay through the control circuit of
Fig. 4 to thereby admit fluid under pressure to the right-hand
end of the cylinder, thereby driving a piston and piston rod to
the left for moving the casing 2 into the left-hand position in
the direction of the arrow D shown in Fig. 1.
The circuit of Fig. 4 produces, after an adjustable time delay,
a signal for admitting fluid under pressure to the left-hand end
of the cylinder 13 to thereby move the casing 2 back into the
right-hand position, thereby opening the slide gate 8 again. As
long as there are no contaminations in the flowing bulk material,
the piston cylinder device 13 will tend to hold the casing 2 in
the normal or right-hand position of Fig. 1. Thus, the material
will ~low in the direction o~ the arrow B to any machine that uses
the material, for example an injection molding machine.
As mentioned above, as long as the casing 2 is in the left-hand
position the slide gate 8 closes the hopper 28. However, if the
casing 2 should have a sufficiently large dimension, the gate 8
might not be necessary, because then the upper side of the casing 2
may close the hopper 28.
The pipe section 15 is secured to the housing 9 and hence stationary.
It may collect any bulk material that might still fall down prior
to the complete closing of the inlet 17 by the gate 8.
Fig. ~ shows a modified embodiment in which the baffle plates 3
and 4 have been replaced by a knee plpe section 20 forming a slanted
channel which is slanted to such an extent that its lower outlet 20'
is horlzontally displaced relative to its upper inlet 22'. The
slanted pipe section 20 has a diameter "b" and the horizontal
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1 displacement "c" is a~ least as large as the diameter "b". Prefer-
ably, the displacement "c" is larger than the diameter "b" by a
spacing "a" as best seen in Fig. 3 to make sure that flowing bulk
material must always impinge on the lower wall portion 20a of the
slanted knee pipe section 20. The embodiment of Fig. 3 functions
in the same manner as the embodiment of Fig. 2. The elongated
slot 19 and the plug-in socket 18 is not shown in Fig~ 3 for
simplicity's sake. However~ the embodiment of Fig. 3 also has
such a plug-in socket 18' for the connection to a flexible electrical
conductor cable.
Rather than using a hydraulic or pneumatic piston cylinder device 13,
it is conceivable to use an electromagnetic solenoid with a high
response characteristic for moving the casing 2 back and forth
to minimize the delay times. It is also possible to move the
casing 2 around a vertical axis in a rotational movement rather
than in the described li~ear movement.
It is also possible to use more than two baffle plates depending
on the retardation of the free flow that is required for any par-
ticular type of material. Similarly, the knee pipe section 20
could have several bends rather than only two.
The type o~ detector will depend on the type of material to be
removed. For example, a detector could be used that responds to
density differences between the contaminating material and the
flowable bulk material. Thus, other materials could be removed,
not only metal, such a~ glass, rocks, or the like.
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1 Although the invention has been described with reference to
specific example embodiments, it will be appreciated, that
it is intended to cover all modifications and equivalents
within the scope of the appended claims.
Fig. 4 shows a block diayram illustrating the control mechanism
for the movement of the flow pipe between its normal position
and its contamination discharye position. An osciallator is
conneted witp a selfmonitoring devlce, a trigger, a driver and
a timer. The sensibility for discharglng can be adjusted by a
sensibility device. To adjust the separation duration a device
is connected with the timer. The timer is connected with an
electropneumatic valve. Thia valve has a first po~ition for the
flow forth of the cylinder device 13 and a second position for
the flow back of the cylinder device 13. Controlling of the valve
i9 ef~ected by a control adjusting device. Compressed air is
regulated by a pres~ure regulator valve and pres~ure can be
inspected by a manometer. A pipe line connects the pressure regu-
lator valve with the electropneumatic valve. The cylinder device
and the electropneumatic valve are connected by two pipe line~
for the movement of the ~iston and therewith the flow pipe forth
and back.
