Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE FOR SEPARATING INDIVIDUAL OR A PLURALITY OF
ROTATIONALLY SYMMETRIC CONTAINERS FROM A STREAM OF
ROTATIONALLY SYMMETRIC CONTAINERS CONVEYED UNDER BACKUP
PRESSURE, AND A CYLINDER HAVING A PISTON EXTENSIBLE IN A
CONTROLLED MANNER
The invention relates to a device for separating
individual or a plurality of rotationally symmetric
containers from a stream of rotationally symmetric
containers conveyed under backup pressure. The device
comprises a first conveyor for the stream of containers
and a second conveyor for removal of the separated
containers, the second conveyor branching off at a
separation point from the first conveyor. The device
further comprises a device for transferring the
containers to be separated from the first conveyor onto
the second conveyor. Since the containers are conveyed
under backup pressure, railings which hold the containers
on the first conveyor are disposed to the right and left
of the first conveyor.
The separation of individual containers from a stream of
such containers conveyed under backup pressure has up
till now been effected exclusively by means of star
wheels.
For separating containers, which are not conveyed under
backL.p pressure and are therefore a mutual distance
apart, many devices are known, e.g. the segmented
separating distributor and the deflection gas nozzles
according to EP-A-0 003 111. Said devices are however not
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suitable for separating containers which are conveyed
under backup pressure.
The present invention enables separation of individual
containers from a stream of such containers conveyed
under backup pressure by means of a reliably operating
device of the simplest possible design, the stream of
containers remaining on the first conveyor, e.g. a
conveyor belt or link chain conveyor.
Accordingly, the present invention provides a device for
separating individual rotationally symmetric containers
from a stream of rotationally symmetric containers
conveyed under backup pressure, comprising
a first conveyor for the stream of containers, the
first conveyor bending at an acute angle at a separation
point;
a second conveyor for removal of the separated
containers) the second conveyor branching off at the
separation point from the first conveyor;
a dividing wedge disposed between the first and the
second conveyor;
a means for determining the speed of the containers
on the first conveyor path upstream of the separation
point;
a first deflection slide, which is disposed at the
separation point next to the first conveyor at the side
of branching of the second conveyor and is extensible
towards the tip of the dividing wedge; and
a second deflection slide, which is disposed at the
separation point next to the first conveyor at the side
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of the bend of the first conveyor and is extensible
towards the tip of the dividing wedge;
wherein, when the first deflection slide (22) is
extended, the containers (10) continue to be conveyed on
the first conveyor (12) and, for separating containers
(11) onto the second conveyor (18), the second deflection
slide (24) is extended and the first deflection slide
(22) is retracted; and
wherein the speed determining means control the
extension speeds of the deflection slides in accordance
with the conveying speed of the containers.
When the first deflection slide is in its extended
position and the second deflection slide is in its
retracted position, the containers are conveyed on the
first, bending conveyor. When a container which is to be
separated arrives at the separation point, its arrival
being detected, for example, by a trigger barrier
situated there, the first deflection slide is retracted
and the second deflection slide is extended so that the
container to be separated is pushed by the containers
following behind onto the branching second conveyor. The
first deflection slide is extended once more immediately
behind the container to be separated and at the same time
the second deflection slide is retracted so that the
containers following behind are once more moved forward
on the first conveyor.
When one or more containers are separated from the
container stream, the gap created is immediately closed
because of the prevailing backup pressure. Closure of the
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gap temporarily gives rise to a sharp acceleration and a
pressure variation which propagates in conveying
direction and counter to conveying direction. To prevent
the jerky movement of the containers causing an error in
the electronic tracking of the individual
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articles, it is advantageous to provide a device for damping said
pressure variation. Such a device may comprise a thin plate,
which is disposed on the first conveyor downstream of the
separation point and by means of which the containers are pushed.
The device according to the invention may be part of a drinks-
decanting installation. Such drinks-decanting installations have
stations, at which the drinks bottles are checked to ensure that
they are flawless, clean and free of foreign bodies. Devices for
inspecting the bases and walls under backup pressure are
described in the simultaneously filed PCT applications "Method
and device for conveying containers past a device for inspecting
the base of the containers" (our reference: 30562/base
inspection) and "method and apparatus for rotating rotationally
symmetrical containers, such as bottles, while transporting them
under backup pressure" (our reference: 30560/auto-rotation). The
fact that both the base inspection and the wall inspection and,
according to the present invention, the separation of individual
containers found to be defective during inspection are effected
under backup pressure means that the entire installation may be
substantially simplified because the filling machines which are
normally used require backup pressure in the intake region. It
is therefore no longer necessary to space out the containers so
that they are a mutual distance apart upstream of the devices for
base and wall inspection or to build up the backup pressure again
afterwards.
The assignment of the result of a base inspection or a wall
inspection to the individual containers is effected by means of
a FIFO shift register, the content of which is progressively
clocked in accordance with the further movement of the containers
on the first conveyor until the relevant container arrives at a
light barrier disposed immediately upstream of the separation
point. The further movement of the containers on the first
conveyor may be determined by means of a star wheel, which is in
engagement with the stream of containers, a CCD line scanning
camera, an array of photodiodes or through speed measurement by
means of the Doppler effect or the like. Said manner of
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assignment of the test result to the individual containers is
known from installations where the articles are conveyed a mutual
distance apart from one another.
Preferably, the dividing wedge is divided in a longitudinal
direction and the two parts are displaceable in each case in the
direction of their outside edges towards the first and second
deflection slide respectively. The respective part of the
dividing wedge and the deflection slide meet approximately in the
middle of the first or second conveyor. A more precise
separation of containers and a higher container throughput rate
is therefore possible.
Operation of the separating device at a higher container
throughput rate is also enabled by providing, immediately
upstream of the deflection slides, swivelling flaps in the
railing of the first conveyor which already impart to each
container a momentum in the direction of the bending part of the
first conveyor or in the direction of the branching second
conveyor, with the result that the change in direction when the
containers encounter the first or second deflection slide is less
abrupt.
A further possibility of improving separation is to pivotally
support the dividing wedge at its broad, downstream end so that
the tip of the dividing wedge is capable of swivelling and so,
once more, the change in the direction of motion of the
individual containers is smaller.
The two deflection slides are advantageously extended by means
of pneumatic cylinders. The speed of their extension corresponds
approximately to the speed of the containers running past. It
is therefore advantageous to be able to control the extension
speed of the pneumatic pistons. This is preferably effected by
using double-action pistons, the flow resistance of the air
exiting from the chamber in front of the piston upon extension
of the piston being controllable by means of adjustable
throttles. The extension and retraction speed of the piston may
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alternatively be controlled by providing a plurality of vent
ports, which are distributed over the length of the cylinder and
are controlled in each case by a valve. When the piston is acted
upon at one end by compressed air and the ports at the other end
5 of the piston are successively opened, the piston is displaced
in steps in each case as far as the port which has just opened.
By said means, the travel distance and also the travel speed of
the piston may be controlled. Such cylinders are also suitable
for other applications where the extension speed or extension
distance is to be variable.
There follows a description of embodiments of the invention with
reference to the drawings. The drawings show:
Fig.1 an embodiment of the device according to the invention
having two deflection slides;
Fig.2 an embodiment of the device according to the invention
having two deflection slides and additionally a
dividing wedge divided in longitudinal direction, each
of the parts being displaceable;
Fig.3 an embodiment of the device according to the invention
having two deflection slides and additionally two
deflection flaps;
Fig.4 an embodiment of the device according to the invention
having two deflection slides and additionally a
swivelling dividing wedge;
Fig.5 a plan view of a star wheel which, for determining the
conveying speed of the containers, is disposed next to
the first conveyor;
Fig.6 the device according to the invention combined with a
line scanning camera for determining the conveying
speed of the containers as well as with a device for
damping pressure impulses;
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Fig.7 the line scanning camera for determining the conveying
speed of the containers in a section at right angles
to the conveying direction;
Fig.8 a diagrammatic view of a cylinder with a gradually
extensible piston, and
Fig.9 a diagrammatic view of a cylinder, in which the
extension speed of the piston is controllable.
According to Fig.1, empty bottles 10 are conveyed under backup
pressure on a first conveyor 12 which may be, for example, a
conveyor belt or a link chain conveyor. The empty bottles 10 are
guided on the first conveyor 12 by means of railings 14. The
distance between the two railings 14 is 1 to 10 mm greater than
the diameter of the empty bottles 10. At a separation point 16,
the first conveyor 12 bends at an angle of around 30° towards one
side, in Fig.1 to the right, and a second conveyor 18 branches
off likewise at an angle of around 30° towards the other side,
in Fig.1 to the left. In so doing, a dividing wedge 20 is formed
between both conveyors 12, 18.
In practice, such an arrangement may be realized by using a
conveyor belt or a link chain conveyor with a width which is
approximately 3 or 4 times the diameter of the empty bottles 10.
The empty bottles 10 are guided by the railings 14 on the link
chain conveyor. In the case of the bend, the link chain conveyor
runs straight on and only the railing 14 is bent. The empty
bottles 10 therefore run in the region of the bend slightly
obliquely relative to the direction of movement of the link chain
conveyor. Similarly, the empty bottles on the branching second
conveyor 18 are displaced by the railing 14 obliquely on the link
chain conveyor. Advantageously, three parallel-running link
chain conveyors overlap at the separation point, the empty
bottles 10 being brought up on the middle link chain conveyor and
being displaced by the bending railing 14 onto the link chain
conveyor running alongside on the right, while they are displaced
by the railing, which branches off in the other direction, onto
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the link chain conveyor running alongside on the left. It is
also possible to guide the containers standing centrally on two
link chain conveyors up to the separation point and move them
there by means of the device according to the invention onto one
of the two conveyors 12, 18. The second conveyor 18 need not be
a linear conveyor and may alternatively be a rotary table.
At the separation point 16, i.e. at the start of the forking of
the two conveyors 12, 18, a first deflection slide 22 and a
second deflection slide 24 are disposed on opposite sides of the
first conveyor 12. Each of the two deflection slides 22, 24
comprises a displaceably supported rod 26, which is tapered at
the front and may be extended and retracted by means of a
pneumatic cylinder 28. The first deflection slide 22 is disposed
at the side of the incoming first conveyor 12 towards which the
second conveyor 18 branches off, and the second deflection slide
24 is disposed at the side of the incoming first conveyor 12
towards which the first conveyor 12 bends. In their retracted
position, the deflection slides 22, 24 are situated outside of
the first and second conveyors 12, 18. The two deflection slides
22, 24 are extensible towards the dividing wedge 20 and extend
in their extended position over at least half the width of the
second and first conveyor 18, 12 respectively. Particularly in
the case of the second deflection slide 24, it is generally
sufficient for it to be extensible only as far as approximately
the middle of the width of the first conveyor 12. The first
deflection slide 22 in its extended position bridges the gap
arising in the railing 14 as a result of the branching of the
second conveyor 18 so that, when the first deflection slide 22
is extended, all of the empty bottles 10 continue to be conveyed
on the first conveyor 12. When a defective empty bottle 11 which
is to be separated arrives at the separation point 16, the second
deflection slide 24 extends immediately after the last preceding
good bottle so that the defective empty bottle 11 is prevented
from moving along on the first conveyor 12. At the same time,
the first deflection slide 22 is retracted so that the empty
bottle 11 to be separated is pushed onto the second conveyor by
the backup pressure exerted by the empty bottles 10 following
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behind. If the next empty bottle is likewise to be separated,
the first deflection slide 22 remains in its retracted position
and the second deflection slide 24 remains in its extended
position. If, on the other hand, the next empty bottle is good
and is to be conveyed further on the first conveyor 12, the first
deflection slide 22 is extended once more immediately behind the
separated empty bottle 11 and the second deflection slide 24 is
retracted, thereby clearing the path again on the first conveyor
12.
In the embodiment shown in Fig.2, instead of a rigid dividing
wedge 20, a dividing wedge 20 comprising two movable tips 30, 32
is used. The tips 30, 32 are displaceable by means of pneumatic
cylinders 34, 36 towards the first and second deflection slide
22, 24 respectively, thereby shortening the extension distance
of the deflection slides 22, 24. The tips 30, 32 are
displaceable as far as the middle of the first and second
conveyor 12, 18 respectively so that the travel distance of the
deflection slides 22, 24 is halved. The travel time is therefore
reduced, with the result that a higher bottle throughput rate is
possible.
In the embodiment of Fig.3, a first and second deflection flap
38, 40 are disposed laterally next to the first conveyor 12
immediately upstream of or at the separation point 16. The
deflection flaps 38, 40 are pivotally supported at their rear
end, and their front end directed in conveying direction may be
swivelled by means of pneumatic cylinders 42, 44. Shortly before
or at the same time as a deflection slide 22, 24 is extended, the
deflection flap 38 or 40 situated immediately behind at the same
side of the first conveyor 12 is activated by the associated
cylinder 42 or 44 in such a way that it imparts to the next
bottle a momentum away from the tip of the deflection slide 22,
24, thereby creating room for the extending deflection slide 22,
24. There is therefore a greater time window for the extension
instant of a deflection slide 22, 24. Since, for example, a
container 11 which is to be separated has already been given a
momentum in the direction of the second conveyor 18 by the second
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deflection flap 40, the second deflection slide 24 may even be
extended relatively late without there being a risk of the second
deflection slide 24 encountering an empty bottle 10.
In the embodiment of Fig.4, the dividing wedge 20 is supported
at its front broad end so as to be capable of swivelling about
an axis 46. Swivelling is effected by means of a pneumatic
cylinder 48. Provided no empty bottle is being diverted onto the
second conveyor 18, the dividing wedge 20 is situated in a
position in which it is swivelled slightly towards the second
conveyor 18, so that the empty bottles 10 may continue to be
conveyed past the dividing wedge 20 on the first conveyor 12.
When an empty bottle 11 to be separated enters the separation
point 16, the dividing wedge 20 is swivelled away from the second
conveyor 18 and towards the first conveyor 12 so that the
extension distance for the second deflection slide 24 is slightly
shortened. This is a further possible way of increasing the
throughput rate of the empty bottles.
The extension speed of the two deflection slides 22, 24
corresponds approximately to the speed of the empty bottles 10
so that the tip of the deflection slides 22, 24, upon extension,
slides between the empty bottles 10 while, as it were, moving
along with said empty bottles. Since the speed of the empty
bottles 10 when being conveyed under backup pressure may vary
dramatically and is lower than the speed at which the first
conveyor 12 is driven, it is advantageous to acquire the speed
at which the empty bottles 10 are moving. To said end, according
to Fig.5, a star wheel 50 may be disposed upstream of the
separation point 16 next to the first conveyor 12, which star
wheel engages with its teeth between the empty bottles 10 and is
driven by the empty bottles 10 as they run past. It is then
possible from the rotational speed of the star wheel 50 to
determine the speed of the empty bottles 10 and control the
extension speed of the first and second deflection slides 22, 24
accordingly. At the same time, it is possible to derive from the
rotation of the star wheel 50 clock pulses for the further
clocking of the result of a base or wall inspection in a FIFO
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shift register, so that in each case the control signal
pertaining to a specific empty bottle and containing the
inspection result is present when the relevant empty bottle
travels through a light barrier, which is disposed immediately
5 upstream of the separation point 16 and by means of which a
separation process is initiated if said empty bottle 10 has been
recognized as defective during the base or wall inspection.
An alternative possibility of measuring the conveying speed of
10 the bottles is by means of a line scanning camera 101 instead of
the star wheel. The line scanning camera is disposed at bottle
mouth height laterally on the conveying device opposite a light
source 100. The conveying speed is calculated from the sequence
of signals of the camera by means of a microprocessor circuit
(Figs.6 and 7). The container stream may be sharply accelerated
in the event of separation of containers owing to the fluctuating
pressure conditions. Incorrect measurements may possibly occur
as a result. It is possible to counteract said behaviour by
setting up a slight mechanical resistance to the container stream
in the form of a damping element in the region between line
scanning camera and separation point. Said damping element may
be realized, for example, by a thin plate 102, which is disposed
on the conveyor and over which the containers glide (Fig.6).
Fig.8 is a diagrammatic view of a pneumatic cylinder 60 having
a plurality of ports 0, 1, 2 ...n distributed over its length.
Each port is connected to a separate control valve 62. A piston
64 with a piston rod 66 is displaceable in the cylinder 60. When
the piston 64 in Fig.8 is to be displaced from its left end
position into its right end position, the port 0 is connected by
its control valve 62 to a compressed-air source, while the
control valves 62 of the other ports are closed. The piston 64
is then unable to travel because air cannot escape at the piston
rod end. The port 1 is then vented via its control valve 62,
with the result that the piston 64 moves to the right until it
closes the opening of the port 1. The control valve 62 for the
port 1 may then be closed. Since the piston has already closed
the opening of the port 1 , control of the control valve 62 is not
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time-critical. By opening the subsequent ports 2, 3, 4 ...n, the
piston 64 may be moved gradually to the right. By closing port
0 and connecting port n to compressed air, the piston 64 may then
be moved gradually to the left by graded-time venting of the
valves n-1 to 1 in reverse order. It is therefore evident that
the piston 64 may also be held in an intermediate position.
Another possible way of controlling the piston speed is shown in
Fig.9, in which a piston 74 with a piston rod 76 moves inside a
cylinder 70. The left end of the cylinder is connectable by a
control valve 72 to a compressed-air source, while the right end
of the cylinder 70 is throttled at the waste gas side by means
of a series of adjustable throttle check valves 78. Each of the
throttle check valves 78 may be bridged by means of a control
valve 80 and a bypass line. When the piston rod is to be
extended at maximum speed, the air is let out through the least
throttled valve. The extension speed may be slowed down by using
more extremely throttled valves 78 to let the air out. The
possibility also exists of using, instead of a plurality of
throttle check valves 78 which may be switched over, one throttle
valve which is adjusted by means of an actuator. Said adjustment
may be effected by means of a stepping motor.
The previously described cylinders 60, 70 are particularly
suitable for controlling the extension speed of the deflection
slides 22, 24, the extension distance also being adjustable by
means of the cylinder 60. Such cylinders may also be used for
purposes other than driving the deflection slides 22, 24 of a
separating device.
By virtue of the cylinders shown in Figs.8 and 9 it is possible
to extend the deflection slides 22, 24 initially at an increased
speed and then, as the tip of the deflection slide 22, 24
approaches the middle of the conveyor belt and there is a risk
of the tip of the deflection slide 22, 24 more or less radially
encountering a container 10 and possibly breaking the latter,
reduce the extension speed approximately to the conveying speed
of the containers 10.
