Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02270146 1999-04-27
METHOD AND APPARATUS FOR WRAPPING BALES END TO END
This invention relates to a method and apparatus for wrapping bales end to end
in a row.
BACKGROUND OF THE INVENTION
To produce silage from grass, cut grass is often gathered to form bales and
wrapped by plastic strip to ferment the grass.
Unit~;d States Patent No. 4,793,124 issued on December 27, 1988 to Anderson
discloses a bale wrapping machine which wraps bales end to end in a row while
allowing
the machine to move along a ground surface. Bales are received by a bale
receiving
support, and moved into a bale wrapping device by a ram cross bar driven by
two
hydraulic rams moving along the sides of the bale receiving support. The
wrapped bales
are moved down to a ground surface along an inclined support as they are
pushed by the
following bales. Such a bale wrapping machine is also called an "in-line
wrapping
machine" in contrast to a "single wrapping machine" which is dedicated to wrap
a single
bale.
In the bale wrapping field, relatively thin plastic strip ~~ commonly used.
Such
thin plastic strip is economical and easy to handle. However, it tends to be
easily
damages by animals, cut edges of grass sticking out of bales, or other
objects. So as to
avoid exposing wrapped bales to air, the plastic strip is often wrapped around
bales such
that the plastic strip is overlapped to form two or more layers of strip on
the bales.
However, this solution slows down the wrapping operation.
It is known to stretch plastic strip in order to tightly wrap bales. If
conventional
thin plastic strip is stretched too much, it may tear in the hot sun.
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In order to prevent damage from poking or tearing, a thicker plastic strip
could
be used. However, such a thicker plastic strip would be more costly. It would
also
require a more complicated mechanism to produce a force large enough to
stretch the
thicker plastic.
It is known in a single bale wrapping machine to stretch two plastic strips
and
laminate them together before wrapping a single bale, using hydraulic powered
stretchers.
It is difficult to move such hydraulic powered stretchers around a bale. Thus,
the
machine rotates the bale relative to the powered stretcher which is supported
by
stationary arms. In order to tightly wrap the bale in two planes, the machine
also changes
the direction of rotation of the bale.
Therefore, it is desirable to provide an in-line bale wrapping machine which
allows for the use of conventional plastic strip in such a way that the
plastic is not easily
poked or torn.
SUMMARY OF THE INVENTION
The present invention uses a plastic strip stretching device which stretches
multiple plastic strips together in ~ lengthwise direction of the multiple
plastic strips for
carrying around a bale by an in-line bale wrapping device during the bale
wrapping
operation.
In accordance with an aspect of the present invention, there is provided a
bale
wrapping machine for wrapping bales end to end in a row. The bale wrapping
machine
comprises a machine mover for enabling the machine to move along a ground
surface
during the wrapping of bales; a bale receiving support for receiving bales; a
bale
wrapping device adjacent the bale receiving support for carrying a stretching
device and
multiple plastic strips around a bale, the stretching device stretching the
multiple plastic
strips together in a lengthwise direction of the multiple plastic strips
during the operation
of the bale wrapping device; an inclined support adjacent the bale wrapping
device for
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transporting wrapped bales to a ground surface; and a bale mover for moving
bales from
the bale receiving support towards the bale wrapping device.
In accordance with another aspect of the present invention, there is provided
a
bale wrapping machine for wrapping bales end to end in a row, the bale
wrapping
machine comprising: a machine mover for enabling the machine to move along a
ground
surface during the wrapping of bales; a bale receiving support for receiving
bales; a
stretching device having a set of free rotating rollers which receives
multiple plastic
strips; a bale wrapping device adjacent the bale receiving support, the bale
wrapping
device having a rotating hoop for carrying the stretching device and the
multiple plastic
strips around a bale and for stretching multiple plastic strips in a
lengthwise direction of
the multiple plastic strips together by the stretching device during the
operation of the
bale wrapping device; an inclined support adjacent the bale wrapping device
for
transporting wrapped bales to a ground surface; and a bale mover for moving
bales from
the bale receiving support towards the bale wrapping device.
In accordance with another aspect of the present invention, there is provided
a
method for wrapping bales end to end in a row using a bale wrapping machine.
The
method comprises the steps of receiving bales by a bale receiving support of
the bale
wrapping machine; moving the bales into a bale wrapping device of the bale
wrapping
machine; carrying multiple plastic strips around each bale by the bale
wrapping device;
stretching the multiple plastic strips together in a lengthwise direction of
the multiple
plastic strips during the operation of the bale wrapping device; moving
wrapped bales
from the bale wrapping device to an inclined support of the bale wrapping
'machine;
transporting the wrapped bales to a ground surface along the inclined support;
and
allowing the bale wrapping machine to move along a ground surface during the
wrapping
of the bales.
Other advantages, objects and features of the present invention will be
readily
apparent to those skilled in the art from a review of the following detailed
description of
preferred embodiments in conjunction with the accompanying drawings and
claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be further understood from the following description with
reference to the drawings in which:
Figure 1 is a side view of a bale wrapping machine having a stretching device
in
accordance with an embodiment of the present invention;
Figure 2 is a perspective view of a bale wrapping machine having a stretching
device in accordance with another embodiment of the present invention;
Figure 3 is a perspective view of a plastic strip Garner having a stretching
device
in accordance with an embodiment of the present invention;
Figure 4 is a side view of the plastic strip Garner shown in Figure 3;
Figure 5 is a partial perspective view of the plastic strip carrier shown in
Figure 3
as installed on a rotating hoop; and
Figure 6 is a side view of a wrapping !device using two plastic strip
carriers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figure 1, an embodiment of a bale wrapping machine 20 having a
plastic strip stretching device 100 in accordance with the present invention
is described.
The bale wrapping machine 20 is capable of wrapping bales 10 end to end in a
row. The machine 20 has a frame 21, and a machine mover 22 which enables the
machine 20 to move along a ground surface during the wrapping operation of
bales. The
bale wrapping machine 20 also has a bale receiving support 24, a bale wrapping
device
26, an inclined support 28 and a bale mover 30. Bales 10 are received by the
bale
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receiving support 24 and translated into the bale wrapping device 26 along the
bale
receiving support 24 by the bale mover 30. The bale wrapping device 26 carnes
multiple
plastic strips (one strip 31 is shown in Figure 1 ) and the stretching device
100 around the
bale 10. Bales 10 wrapped by the bale wrapping device 26 are pushed down the
inclined
support 28 to a ground surface by the following bales. Thus, bales 10 are
wrapped end
to end in a row, resulting in a row of wrapped bales lying on the ground along
the track
of the machine 20 due to the movement of the machine 20 enabled by the machine
mover 22.
The bale wrapping machine 20 shown in Figure 1 has, as the machine mover 22,
three wheels in each side. The machine mover 22 may be also skis, sleds or any
one or
more mechanisms which allow movement of the machine 20 along the ground
surface
during the bale wrapping operation.
The bale receiving support 24 may have a roller bed 24a comprising multiple
rollers arranged to facilitate the movement of bales 10 along the receiving
support 24.
The inclined support 28 may also have a roller bed 28a comprising multiple
rollers arranged to facilitate the movement of bales 10 along the inclined
support 28. The
tail Pnd 29 of the inclined support 28 may be folded up or folded over the
rest of the
inclined support 28 when the machine 20 is not in use or carned to other
locations.
Figure 2 shows another embodiment of a bale wrapping machine 20'. Similar
elements to those in Figure 1 are shown with the same reference numerals.
The bale wrapping device 26 shown in Figure 2 comprises a rotating hoop 27a
for carrying plastic strips 31 and the stretching device 100 around a bale 10.
The rotating
hoop 27a is rotatably supported by a fixed hoop 27b provided on the frame 21
of the
machine 20. The rotating hoop 27a and the fixed hoop 27b may have different
shapes,
and may be located in different arrangements. For example, instead of the
fixed hoop
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27b, the rotating hoop 27a may be supported by one or more fixed supports of a
different
shape provided on the frame 21.
During the wrapping process, bales 10 are moved from the bale receiving
support
24 into the rotating hoop 27a of the bale wrapping device 26 by the bale mover
30. The
bale wrapping device 26 is located at a gap 25 between the bale receiving
support 24 and
the inclined support 28. Bales may be supported over the gap 25 by the
pressure between
the preceding bales and the bale mover 30. There may be one or more additional
supports provided in the gap 25 between the bale receiving support 24 and the
inclined
support 28.
The rotating hoop 27a of the bale wrapping device 26 is rotated about its axis
by
a rotating driver (not shown).
It is preferable to synchronize the rotation of the rotating hoop 27a and the
movement of the bale mover 30 in such a way that the rotating hoop 27a is
rotated as a
bale 10 is moved through the rotating hoop 27a. Rotation of the hoop 27a is
stopped
when the bale is completely or partially wrapped. The rotational speed of the
hoop 27a
may be varied to adjust the amount of overlap of plastic strips 31 on wrapped
bales.
The bale mover 30 may use any moving mechanism and power source as long as
it can move bales along the receiving support 24 to the bale wrapping device
26. A
hydraulic ram mechanism may be conveniently used. In the embodiments shown in
Figures l and 2, the bale mover 30 comprises a ram cross member 32 and a pair
of
hydraulic rams or ram cylinders 34 extending along the sides of the bale
receiving
support 24. The ram cross member 32 is supported across the pair of rams 34
adjacent
the bale wrapping device 26, and moved by the rams 34 between a bale receiving
position
32a for receiving a bale and a bale pushing position 32b for pushing the bale
towards the
bale wrapping device 26. In the embodiment shown in Figure 1, the rams 34 are
provided in such a way that the ram cross member 32 is positioned at the bale
receiving
position 32a when the rams 34 are extended, and the ram cross member 32 is
positioned
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at the bale pushing position 32b when the rams 34 are retracted. The rams 34
may be
provided in the reverse direction as shown in Figure 2.
In accordance with the present invention, the bale wrapping machine 20 uses
multiple plastic strips 31 which pass through the plastic strip stretching
device 100. The
bale wrapping device 26 carries the plastic strip stretching device 100 and
multiple
plastic strips 31 around a bale 10. During the operation of the bale wrapping
device 26,
the stretching device 100 stretches the multiple plastic strips 31 together in
their
lengthwise direction in cooperation with the bale being wrapped.
Stretching multiple plastic strips together is advantageous because the
resultant
multi-layered strip becomes stronger than a single strip. The in-line bale
wrapping
machines are often used to wrap large round bales end to end in a continuous
manner.
When the wrapped bales are moved along the inclined support, localized forces
may be
generated in the plastic strip wrapping between bales. By using stronger
plastic strips,
the bales are moved without tearing the plastic strips between the bales.
The present invention allows use of relatively thin plastic strips
conventionally
used for wrapping bales. The plastic strip does not have to be overlapped as
much on the
bales.
As a thicker plastic strip is not required to provide sufficient strength in
the
wrapping, the present invention does not require a powered stretcher which
would be
required to stretcr: a thicker plastic strip.
Also, by stretching together, plastic strips tend to stretch more
without.brakeage,
compared to stretching each plastic strip separately. Since mufti-layered
strip can be
stretched more than single layer strip, more bales can be wrapped before the
reels must
be replaced.
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It is preferable to use one or more plastic strips having a tacky surface or
surfaces.
By using tacky plastic strips, multiple plastic strips are laminated when they
are stretched
together and stay laminated on bales. Thus, the resultant multi-layered strip
becomes
even stronger.
Use of multiple plastic strips also allows flexibility in selecting materials
of
plastic strips.
It is preferable to prevent the light from entering into bales, and to prevent
the
plastic from becoming too hot. Conventionally, either a black plastic strip or
a white
plastic strip is used to wrap bales. White plastic strip is advantageous
because it reflects
light and thus stays cooler. However, black plastic strip has the advantage of
letting less
light through to the baler.
Use of multiple plastic strips allows a combination of different plastic
strips. For
example, a combination of a white and black plastic strip may be used to form
an outer
layer on bales with the white plastic strip, and an inner layer on bales with
the black
plastic strip.
Any form of plastic strips may be used as long as they are suitable for
wrapping
bales. Reels of plastic strips may be conveniently used.
The stretching device 100 may be supported by a plastic strip carrier frame
102
together with reels of plastic strips 31. The carrier frame 102 is in turn
supported by the
bale wrapping device 26 and carned around a bale 10.
Figures 3 to 6 show a preferred embodiment of the stretching device 100
together
with a plastic strip carrier 200 for carrying two reels of plastic strips 31
a, 31 b. The
stretching device 100 and the plastic strips 31 a, 31 b are supported by a
carrier frame 102.
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The stretching device 100 comprises a set of rollers having three free
rotating
rollers 104a, 104b and 104c.
The present invention allows use of free rotating rollers because there is no
need
to actively control tension applied to the plastic strips. When wrapping bales
end to end,
there is no need to wrap ends of bales which are covered by neighbouring
bales. Hence,
the surfaces of bales to be wrapped are generally located at the same position
within the
wrapping device. Accordingly, the wrapping device can wrap each bale
substantially in
the same condition. Therefore, there is no need to use powered stretchers to
provide a
constant tension applied to the plastic strips. By contrast, a single wrapping
apparatus
needs a powered stretcher because it is required to wrap different surfaces
having
different shapes of bales.
The first roller 104a receives the plastic strips 31 a and 31 b together. The
plastic
strips 31 a and 31 b are passed through between the first and second rollers
104a and 104b,
and between the second and third rollers 104b and 104c. During the wrapping
operation
of the bale wrapping device, the plastic strips 31a and 31b are stretched
together by
friction of the rollers 104a, 104b,104c in cooperation with the bale wrapping
device, i.e.
a tension caused in the plastic strips by the bale which is being wrapped.
The first roller 104a is preferably positioned at a position close to the
second
roller 104b. Thus, the plastic strips 31a, 31b can be applied with stronger
friction and
stretched more. Also, when the plastic strips 31 a and 31 b pass between these
two rollers
104a, 104b, they are brought into contact with each other. When at least one
of the
contacting surfaces of the plastic strips 31a, 31b is tacky, the strips 31a
and 31b are
laminated together.
It is preferable that the first roller 104a is movable away from the second
roller
104b. When the strips 31 a, 31 b are installed, by moving the first roller
104a away from
the second roller 104b, free ends of the strips 31 a, 31 b are easily passed
through between
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the first and second rollers 104a,104b. In order to move the first roller
104a, a pivotable
lever 106 is provided in the stretching device 100.
The carrier frame 102 is provided with recesses 108a, 108b for receiving the
reels
of plastic strips 31 a, 31 b.
In order to prevent intrusion of broken grass or dirt between contacting
surfaces
of the plastic strips 31a, 31b, it is preferable to provide a shield 110 to
cover at least
exposed parts of the contacting surfaces of the plastic strips 31a, 31b.
In use, one end 102a of the earner frame 102 is attached to the rotating hoop
27a,
as shown in Figure 5.
In this embodiment, the rotating hoop 27a rotates in the direction shown by an
arrow 112. Using three rollers 104a, 104b, 104c, the plastic strip 31 a
becomes an outer
layer on the bale. It is preferable to use a white strip as the plastic strip
31 a, and a black
strip as the plastic strip 31 b.
As shown in Figure 6, it is preferable to provide two sets of the stretching
device
100 and the plastic strip carrier 200 at the opposite sides of the rotating
hoop 27a. More
than two sets of the stretching device and the plastic strip earner may be
also used. By
using multiple sets, the wrapping may be earned out efficiently.
While particular embodiments of the present invention have been shown and
described, changes and modifications may be made to such embodiments without
departing from the true scope of the invention. For example, the rams may be
provided
in the other direction, or a single ram or more than two rams may be used for
the bale
receiving support. The number of hoops used, the design, the rotating
direction of the
bale wrapping device may be also modified. In the stretching device, the
number of
rollers and arrangement of the rollers may be changed. The number of plastic
strips used
and arrangement of them may be also changed.
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