Note: Descriptions are shown in the official language in which they were submitted.
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A nrethod and an apparatus for ianpro~ing functioning of a
w~appirig anachine
METHOD OF THE INVENTION
The present invention relates to a method for improving the operating
efficiency of a
wrapping machine, in which wrapping method
- at least two plastic film band rolls are placed inside the wrapping machine,
- plastic film band from at least one roll vis v~rrapped about the object to
be wrapped
next,
- after the object has been wrapped up, the plastic film band is seamed and
severed,
whereupon the next object can be wrapped,
- and that the wrapping action can be continued until the plastic film band on
the roll
has been used up.
~5 PRIOR-ART METHOD
According to a prior-art wrapping method, the wrapping machine is stopped when
the
plastic film band on the roll has been used up. After that, the empty roll is
replaced with a
full one either manually or by means of an automatic roll changing mechanism.
However,
changing the roll always involves the waste of a considerable deal of valuable
wrapping
20 time.
In a manual roll changing operation, first the safety screen of the wrapping
machine is
opened and then also the wrapping carriage inside the wrapping machine. The
empty roll
on the wrapping carriage is removed and replaced with a full roll. Finally,
the wrapping
25 carriage and the safety screen of the wrapping machine are closed.
An automatic roll changing operation also takes a long time because even in
this case
the roll changing mechanism must first get the empty roll out of the stopped
wrapping
machine and then bring in a full roll to replace the empty one from outside
the wrapping
3o machine.
APPARATUS OF THE INVENTION
The invention also relates to an apparatus for improving the operating
efficiency of a
wrapping machine, said wrapping machine comprising
35 - at least two wrapping devices, such as wrapping carriages, provided with
plastic film
band rolls to allow plastic film band to be wound about the object to be
wrapped,
- and means for seaming and severing the plastic film band.
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PRIOR-ART APPARATUS
A known solution is to provide the wrapping machine with an automatic device
for
changing the plastic film band roll, by means of which an exhausted plastic
film band roll
can be replaced with a full one. The change of rolls is performed with the
wrapping
machine in a fully inactive state. The changing mechanism extracts the empty
roll from
inside the wrapping machine and moves it out of the machine. After that, the
changing
mechanism takes a full roll onto the wrapping carriage inside the machine.
1o However, the automatic roll changing mechanism is technically complicated
and its
operation takes a relatively long time because the wrapping machine has to be
brought to
a complete standstill for the duration of the roll change. The roll changing
mechanism
must first get the empty roll out of the wrapping machine and then bring in a
full roll from
outside the machine to replace the exhausted one.
OBJECT OF THE INVENTION
The object of the invention is to achieve a method and an apparatus for
improving the
operating efficiency of a wrapping machine which do not have the above-
described
disadvantages.
FEATURES CHARACTERISTIC OF THE METHOD OF THE INVENTION
The method of the invention is characterized in that, after one plastic film
band roll has
been used up, wrapping is continued from another, full plastic film band roll
placed inside
the wrapping machine.
It is obvious that substantially faster operation is achieved if wrapping is
continued from a
roll already at hand than if a new roll has to be brought in from outside the
wrapping
machine.
3o EMBODIMENTS OF THE METHOD OF THE INVENTION
According to a preferred embodiment of the method of the invention,
each plastic film band roll is placed on a separate wrapping device, and that
after the plastic film band roll being used for wrapping has been exhausted,
the
wrapping operation is continued using another wrapping device which contains a
full
plastic film band roll.
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According to a second preferred embodiment of the method of the invention, the
wrapping operation is started or continued using a wrapping device containing
a full
plastic film band roll by gripping the end of the plastic film band coming
from the full
plastic film band roll and locking it in place before starting the wrapping of
the next object
to be wrapped.
FEATURES CHARACTERISTIC OF THE APPARATUS OF THE INVENTION
The apparatus of the invention is characterized in that the wrapping machine
comprises
means for switching the wrapping process from an exhausted plastic film band
roll to a
~o full plastic film band roll.
The means for switching the wrapping process from one roll to another are
technically
simple and therefore reliable in operation.
~5 EMBODIMENTS OF THE APPARATUS OF THE INVENTION
A preferred embodiment of the apparatus of the invention is characterized in
that
- the wrapping machine comprises at least two separate wrapping devices, such
as
wrapping carriages, containing a plastic film band roll, and that
- the wrapping machine is provided with a switch-over gripper for gripping the
end of
2o the plastic film band coming from a full plastic film band roll.
A second preferred embodiment of the apparatus of the invention is
characterized in that
- the switch-over gripper can be moved to a position near the end of the
plastic film
band coming from the plastic film band roll and in a direction away from said
plastic
25 film band end, and that
a seaming gripper is placed near the path of the switch-over gripper, and that
the seaming gripper has been arranged to grip the plastic film band drawn out
from
the plastic film band roll by the switch-over gripper.
3o A third preferred embodiment of the device of the invention is
characterized in that the
wrapping device, such as wrapping carriage, containing a plastic film band
roll is provided
with a holder in which the end of the plastic film band is set so that it can
be gripped by
the switch-over gripper.
35 EXAMPLES OF EMBODIMENTS
In the following, the invention will be described by the aid of a few examples
with
reference to the attached drawings, wherein
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LIST OF DRAWINGS
Fig. 1 presents a diagrammatic side view of a wrapping machine with two
wrapping
carriages.
Fig. 2-4 present the wrapping machine of Fig. 1 at different stages of a roll
change
operation.
Fig. 5 presents the wrapping machine of Fig. 1 at the start of a wrapping
operation.
Fig. 6 presents the wrapping machine of Fig. 1 in diagrammatic top view.
~o DESCRIPTION OF THE DRAWINGS
Fig. 1 presents a side view of a wrapping machine 10 for winding a plastic
film band 32
about an object 60 to be wrapped, which is placed on a conveyor track 61. In
this
example, the wrapping machine 10 is a ring-type wrapping machine with a
hoisting frame
20 vertically movable along vertical rails 21. Supported by support rollers 23
on the
~5 hoisting frame 20 is the rotating ring 22 of the wrapping machine 10,
carrying two
wrapping carriages 30a and 30b. Attached to the hoisting frame 20 is a seaming
unit 40
provided with a gripper 41 for gripping the plastic film band as well as means
for seaming
and severing the plastic film band.
2o Each wrapping carriage 30a and 30b carries a roll 31a, 31b of plastic film
band 32a, 32b
to be wound about the object to be wrapped 60. In the wrapping carriages 30a
and 30b,
the ends 33a and 33b of the plastic film bands are placed in holders 34a and
34b. The
wrapping machine 10 further comprises a switch-over gripper unit 50, which
moves
horizontally on a slide 52. The switch-over gripper unit 50 is provided with
gripper jaws 51
2s which can grip the plastic film band ends 33a and 33b in the holders 34a
and 34b on the
wrapping carriages 30a and 30b. In a roll change situation, the rotating ring
22 of the
wrapping machine 10 is turned to a position such that the holder 34a of the a
plastic film
band end 33a on one of the wrapping carriages, in Fig. 1 wrapping carriage
30a, is
aligned with the gripper jaws 51 of the switch-over gripper unit 50.
Fig. 2 illustrates the initial stage of a roll change operation in the
wrapping machine 10. At
this point, the switch-over gripper unit 50 has been raised so that the
gripper jaws 51 are
at the level of the plastic film band ends 33a and 33b in the holders 34a and
34b of the
wrapping carriages 30a and 30b. While the switch-over gripper unit 50 is
moving
horizontally on the slide 52, in Fig. 2 to the left, the gripper jaws 51 are
opened.
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In Fig. 3 the gripper jaws 51 of the switch-over gripper unit 50 of the
wrapping machine
have gripped the end 33a of the plastic film band. After that, the switch-over
gripper
unit 50 has moved to the right in Fig. 3 along the slide 52, so that the
plastic film band
end 33a has been released from the holder 34a. The jaws 51 of the switch-over
gripper
5 unit 50 have pulled the plastic film band end 33a and the plastic film band
32a off the roll
31 a so that the plastic film band 32a has now reached the gripper 41 of the
seaming unit
40.
In Fig. 4, the gripper 41 of the seaming unit 40 of the wrapping machine 10
has engaged
1o the plastic film band 32a and the gripper jaws 51 of the switch-over
gripper unit 50 have
been opened. This situation corresponds to a situation in a prior-art wrapping
machine
where the end of the plastic film band to be used for wrapping has been set
info the
gripper of a seaming unit to allow the wrapping to be started or continued
from a new, full
roll.
In Fig. 5, the gripper 41 of the seaming unit 40 of the wrapping machine 10
has turned
into a horizontal position in a known manner and the ring 22 with the wrapping
carriages
30a and 30b has started to rotate, so the wrapping of the object 60 with
plastic film band
32a has begun. At the same time, the switch-over gripper unit 50 has returned
to its initial
2o position, i.e. to the low position so that it is out of the way of the
circulating wrapping
carriages 30a and 30b.
In Fig. 5, the object 60 is being wrapped with plastic film band 32a obtained
from a roll
31 a on wrapping carriage 30a. The roll 31 b on the other wrapping carriage
30b attached
to the rotating ring 22 is circulating with the ring but only as a stand-by
roll ready for use
when roll 31a is exhausted. When roll 31a runs out of plastic film band, the
wrapping is
continued using the roll 31 b on the other wrapping carriage 30b. Roll 31 b is
put into
active use by steps identical with those for roll 31a as illustrated in Fig. 2-
4. However,
since both rolls 31 a and 31 b are already within the wrapping machine 10, the
roll change
so can be performed substantially faster and more effectively than in prior-
art wrapping
machines, in which the new roll is always brought in from outside the machine.
Fig. 6 presents a simplified top view of the wrapping machine 10 in Fig. 1. As
shown in
the figure, the rotating ring 22 of the wrapping machine 10 is provided with
two wrapping
carriages 30a and 30b, each carrying a plastic film band roll 31 a, 31 b. The
end of the
plastic film band 32a, 32b on each roll 31 a, 31 b is placed in a holder 34a,
34b attached to
the wrapping carriage 30a, 30b.
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Fig. 6 illustrates an initial situation in which each wrapping carriage 30a,
30b of the
wrapping machine 10 is provided with a full plastic film band roll 31a, 31b.
In preparation
for the start of the wrapping action, the rotating ring 22 has been turned to
an initial
s position such that the end 33a of the plastic film band 32a in the band
holder 34a of the
first wrapping carriage 30a is aligned with the jaws 51 of the switch-over
gripper unit 50.
Next, the switch-over gripper unit 50 moves to the left in Fig. 6 and the
gripper jaws 51
grip the end 33a of the plastic film band 32a in holder 34a, as is also shown
in Fig. 2.
After that, the gripper jaws 51 pull the end 33a of the plastic film band 32a
to the right in
Fig. 6 so that the plastic film band 32a extends across the gripper 41 of the
seaming unit
40. This situation is also illustrated in Fig. 3. The gripper 41 now engages
the plastic film
band 32a and the jaws 51 of the switch-over gripper unit 50 are opened, as is
also shown
in Fig. 4. After the switch-over gripper unit 50 has moved down to be out of
the way of the
wrapping carriages 30a and 30b, the machine can start wrapping the object 60
on the
conveyor track 61 from the roll 31 a on wrapping carriage 30a.
ADDITIONAL REMARKS
It is obvious to the person skilled in the art that different embodiments of
the invention
2o may be varied within the scope of the claims presented below. Thus, the
invention is not
limited to the ring-type wrapping machine presented in the drawings. In a
corresponding
manner, other types of wrapping machine can equally well be provided with two
or more
wrapping carriages or similar wrapping devices for winding a plastic film
band, so that a
substantially more effective roll change can be achieved.
