Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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AUTOMATIC ALIGNMENT APPARATUS AND METHOD
The invention relates to an automatic alignment apparatus and method for flat
polygonal articles. It is particularly suitable for situations where it is
desired that the
article is to be correctly aligned before being cut. This includes devices
such as
sandwich cutters where a substantially square sandwich is cut in half
diagonally.
Prepackaged sandwiches represent a huge commercial market, and a large
proportion of these comprise two substantially square slices of bread
enclosing a
filling. Such sandwiches are often cut in half diagonally and sold in
triangular
prismatic packs. It is therefore advantageous to use a device which cuts these
sandwiches automatically. It is important that these devices align the
sandwiches so
that they are accurately cut from corner to corner.
Automatic cutting devices for sandwiches, particularly those suitable for use
on production lines are known. In one such device sandwiches arranged so as to
have
one corner pointing roughly in the direction of travel, and so forming the
leading
corner of the sandwich, are conveyed towards a precision alignment section
comprising a pair of gates. Each gate is oriented at 45 degrees to the
direction of
travel. When they are closed the gates resemble a funnel in the direction of
travel. As
the sandwich travels along the production line it runs up against the gates
and stops.
The leading corner is guided into the apex of the funnel formed by the gates.
When it
is determined by a sensor that the sandwich is correctly aligned the gates
open to
allow the sandwich to travel down the device to the cutting section. A
disadvantage is
this method is that sandwiches made of bread slices which are not precisely
square
may not be accurately cut from corner to corner.
A second device is known in which the sandwich is conveyed into an
alignment section comprising four fingers. An example of such a device is the
"Sandwich Aligner and Cutter" manufactured by Advanced Food Technology. The
fingers are arranged in two pairs. One pair located downstream contacts the
leading
corner of the sandwich (as referred to above) and another pair located
upstream
aligns the trailing corner of the sandwich. When a sandwich on a passing
conveyor
belt is in position for alignment each pair has one finger either side of the
sandwich,
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on a respective line perpendicular to the direction of travel. The downstream
pair is
roughly aligned with the leading corner of the sandwich and the downstream
pair is
roughly aligned with the trailing corner. A sandwich in position for alignment
is
detected by a photocell. The sandwich is paused briefly and lifted, with the
conveyor
belt, into an alignment position whereupon the fingers of each pair close
together,
perpendicular to the direction of travel, to align the corners of the sandwich
precisely.
When it is determined that the sandwich is correctly aligned, the sandwich is
released
by the fingers and, again with the conveyor belt, drops free of the fingers to
be
conveyed towards the cutting section.
The fingers of each pair can be adjusted using an eccentric cam arrangement
to ensure that when they close, the sandwich is perfectly aligned before
starting the
cutting process.
In any production line it is desirable to provide as large a throughput as
possible. One way in which throughput can be increased is to stack the
sandwiches so
that more than one sandwich is cut for each alignment and cutting cycle.
However, a
problem inherent in both these devices is that the sandwich must pause briefly
during
the alignment process. It is an object of the present invention to solve this
problem.
Accordingly, a first aspect of the present invention provides an automatic
aligning apparatus for aligning a substantially flat article comprising;
conveyance means acting on the bottom of said article to convey said article
through the apparatus,
sensing means to sense when said article is in position for alignment,
alignment means to align said article when said sensing means sense it is in
position,
at least one actuator to move said alignment means so as to align said article
correctly, and
control means to control said at least one actuator;
characterised in that said alignment means is mounted on a carrier, and
in that said carrier moves said alignment means with a velocity substantially
the same as that of said moving article while alignment is carried out.
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A second aspect of the present invention also provides a method of aligning a
substantially flat article moving along a production line comprising the steps
of:
determining whether said article is in position to be aligned,
when it is determined that said article is in position to be aligned, moving a
S carrier, on which is mounted alignment means, with a velocity substantially
the same
as that of said moving article,
effecting the alignment of said article while said carrier is moving, and
returning said carrier to said position when said alignment of said article
has
been carried out.
In this way the present invention allows an article to be aligned without
needing to stop it to carry out the alignment. This gives a greater throughput
increasing production line efficiency.
A preferred embodiment of the invention will now be described, by way of
example only, with reference to the accompanying drawings in which:-
1S Figure I is a side elevation of the embodiment;
Figure 2 is a cross section through one pair of pneumatic actuators;
Figure 3a is a plan view of the alignment section of the embodiment, prior to
aligning
the article; and
Figure 3b is a plan view of the alignment section of the embodiment, after
aligning
the article.
Figure 1 shows the overall arrangement of the apparatus: A belt 1 runs for the
entire length of the apparatus, it includes an entry end and an exit end, and
is used to
convey through the apparatus the sandwich 4 to be cut. The sandwich 4 to be
cut is
placed on the belt I at the entry end so that one (leading) corner is pointing
roughly
2S towards the exit end of the belt, leading the rest of the sandwich. The
sandwich is
then conveyed by the belt I into an alignment section 2 which positions the
sandwich
so that both the leading and the trailing corners are correctly aligned with
the cutting
blade S of the cutting section 3. A detailed description of the action of the
alignment
section is given below. As the sandwich leaves the alignment section 2 it
enters the
cutting section 3. The cutting section 3 cuts the sandwich in half from corner
to
corner. Finally, the cut sandwich leaves the apparatus via the exit end of the
belt 1
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(on the right of Figure 1) ready for packaging in a further section of the
production
line (not illustrated).
The construction and operation of the alignment section 2 will now be
described in detail. As shown in Figure 3a, the sandwich 4 arrives in the
alignment
section roughly aligned with a leading corner at its front. The movement of
four
cylindrical fingers 7 then causes the sandwich 4 to be aligned as shown in
Figure 3b.
The fingers 7 are connected to a carrier 6 and extend vertically with respect
to
the plane of the belt 1. They are pivotally connected to the carrier 6
allowing them to
move in a plane normal to their axis. The external surface of each finger is
enclosed
by a freely rotatable sleeve. The fingers are arranged in two pairs. Each pair
has one
finger at either side of the belt 1 on a respective line perpendicular to the
direction of
travel 16. The two pairs are spaced apart by approximately the side dimension
of the
sandwich 4.. Movement of the fingers 7 is actuated by a pneumatic ram 8 via an
air
supply 10. Each finger 7 has a bolt (not shown) Which allows adjustment
relative to
its respective pneumatic ram 8. Although a pneumatic ram 8 has been used as an
actuator in this embodiment, the person skilled in the art will appreciate
that other
actuators, for example a gearing system, could also be used.
Figure 2 illustrates the arrangement of one pair of fingers 7a,7c either side
of
the belt. Each forger is moved by the pneumatic ram 8a and 8c respectively.
Figure 2
shows two of the positions that can be adopted by the pair of fingers 7a and
7c. Solid
lines indicate the position in which they are far apart. Dashed lines indicate
the
position in which they are close together.
The carrier 6 is mounted using a motorised gearing system onto the rack 12.
This allows the carrier 6, the attached fingers 7 and actuators 8 to move
along the belt
in a controlled manner with substantially the same direction and speed as a
sandwich
on the belt. The distance 15 that the carrier can move along the direction of
travel 16
is typically 75 mm. Although rack system 12 is used to move the carrier 6 in
this
embodiment, the person skilled in the art will appreciate that an alternative
system
could also be used.
A stainless steel shelf 11 supports the sandwich as it travels through the
alignment section. A photoelectric sensor 9 is provided on the side of the
carrier 6
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facing the belt 1 to detect when a sandwich 4 has entered the aligning
section.
The operation of the alignment section 2 will now be described with reference
to Figures 3a and 3b. Before a sandwich 4 is conveyed into the alignment
section 2,
the earner 6 is positioned at the entry end of the rack 12 so that it can move
along the
rack 12 together with the sandwich 4 during the aligning process. (This is the
position shown in Figure l.) The fingers 7 are positioned as follows (Figure
3a): the
fingers 7a and 7c towards the exit end of the apparatus are spaced so as to
intercept
the leading corner of the sandwich 4. The fingers 7b and 7d towards the entry
end of
the apparatus are spaced apart by a great enough distance to ensure that the
sandwich
4 can pass between them without being obstructed by these fingers.
When the photoelectric cell 9 indicates that a sandwich has entered the
alignment section 2 and that one of its leading edges is in contact with
either the
finger 7a or 7e, the control system 14 operates to move the carrier 6 along
the
direction of travel 16 of the belt, at the same speed as the belt, towards the
exit end of
the apparatus. While the carrier 6 is in motion the control system sends a
signal to the
pneumatic rams 8 to cause them to move fingers 7b and 7d together. As fingers
7b
and 7d move together one of them will come into contact with a trailing edge
of the
sandwich 4 and cause it to rotate on the belt 1. This will also cause rotation
between
the sandwich 4 and the fingers 7, which is accommodated by the rotatable
sleeve.
When the motion of fingers 7b and 7d is complete the sandwich 4 has been
rotated so that both of its corners are in alignment with the cutting blade 5
as shown
in Figure 3b. The control system determines when the motion of the fingers
7b,7d is
complete and the sandwich 4 is aligned correctly.
If the sandwich had already been aligned it would have been contacted
simultaneously by the forger 7b and finger 7d and would not have been moved by
them.
The control system 14 then sends a signal to the pneumatic rams 8 to cause
them to stop moving fingers 7b and 7d together and instead move fingers 7a and
7c
apart. Fingers 7a and 7c are moved far enough apart to ensure that the
sandwich can
pass through them unobstructed. When the control system 14 determines that
fingers
7a and 7c are far enough apart, it sends a signal to the pneumatic rams 8 to
stop all
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motion of the fingers 7.
The control system 14 then stops the motion of the carrier 6 towards the exit
end of the apparatus and sends a signal to make it move towards the entry end
of the
apparatus back to its starting position. As the carrier travels back to the
starting
position the control system 14 determines from the photoelectric sensor 9 when
the
sandwich 4 is no longer located between the angers 7. It then instructs the
pneumatic
rams 8 to move the forgers 7 so that forgers 7b and 7d are apart and fingers
7a and 7c
are together as positioned at the start of the process.
The control system 14 stops the movement of the carrier 6 when it has
travelled as far towards the entry end of the apparatus as the rack 12 allows
it. The
alignment process can then be repeated for the next sandwich which the belt 1
carries
into the alignment section 2.
Although a certain pattern of operation of the fingers to align the sandwich
has been described in this embodiment, the person skilled in the art will
appreciate
I5 that other systems of moving the fingers will also achieve the same effect.
The
person skilled in the art will also appreciate that alternative alignment
systems, for
example one based on the gate system identified in the prior art, could also
be
mounted on the carrier instead of the finger system.
The construction and operation of the cutting section 3 will now be described.
The cutting section 3 includes an extra belt 13, which presses on top of the
sandwich
to ensure that the sandwich 4 remains in the correct alignment throughout the
cutting
process. The belt 13 moves in the same direction at the same velocity as belt
I.
Preferably, belt 13 is adjustable in height to accommodate the height of the
sandwich
4 to be cut. If this is the case, the height adjustment also allows the
cutting section 3
to cut a stack of more than one sandwich at a time, further increasing
throughput.
Some distance along the cutting section 3 there is located a vertical blade 5.
The blade 5 is located in the centre of the belts 1 and 13 with its cutting
edge facing
towards the oncoming sandwich 4. The cutting edge may be designed to minimise'
the spreading of the sandwich fillings. For example, in this embodiment, the
blade 5
is typically 0.5 mm thick. This allows the blade 5 to cut the sandwich 4 with
minimal disturbance to the sandwich filling.
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The blade 5 moves with a vertical reciprocating motion so as to cut the
sandwich. To allow the blade 5 to operate without obstruction each of the
belts 1, 13
are split 1 a, lb in a longitudinal direction to allow the blade 5 free
motion.
After the belts 1,13 have conveyed the sandwich 4 through the cutting section
it exits the apparatus with a perfectly aligned corner-to-corner cut.
The present invention therefore achieves correct alignment of sandwiches
with no need to pause the motion of the sandwich. The applicant has discovered
that
this allows a signif cant increase in the throughput of a cutting production
Line from
typically 45 cycles per minute to typically 60 cycles per minute in the
present
invention.
Although the above described embodiment has related specifically to
sandwiches, the person skilled in the art will realise that it could easily be
adapted to
cut any similar flat article from corner-to-corner. Likewise, although the
alignment of
a square item has been considered the invention could equally be applied to
rectangular items, or indeed any item which requires aligning and then being
cut.
