Package making – Methods – Applying a partial cover
Reexamination Certificate
2001-11-02
2003-04-22
Sipos, John (Department: 3721)
Package making
Methods
Applying a partial cover
C053S438000, C053S529000, C053S587000
Reexamination Certificate
active
06550222
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wrapping a load with packaging material, and more particularly, to stabilizing the load while the load is wrapped with packaging material.
2. Description of the Related Art
Various packaging techniques have been used to build a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, and protection and waterproofing. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch wrap packaging material around a load. Stretch wrapping can be performed as an inline automated packaging technique which dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by turntable, rotating arm, or rotating ring typically covers the four vertical sides of the load with a stretchable film such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and a packaging material dispenser to wrap packaging material about the sides of the load.
Wrapping packaging material about the sides of the load typically unitizes and stabilizes the load. However, such side wrapping by itself generally does not secure the load to the pallet in a manner which would promote increased stability. Due to the structure of a typical stretch wrap apparatus, it is difficult to stabilize the load during wrapping and to secure the load to the pallet in a stable manner.
To increase stability to the load during the wrapping cycle, top platens are used.
FIG. 2
illustrates how a conventional top platen
101
typically provides stability to a load
102
being wrapped. In
FIG. 2
, a load
102
is “column stacked.” In a column stacked configuration, boxes
110
(or whatever is stacked to comprise the load
102
) are not interlocked with layers above or below, rather, box walls are flush.
This is the most unstable type of load. Without a top platen
101
or other type of support, rotation often leads to column tilt
124
, shown in phantom in
FIG. 2
, and sometimes to collapse. The top platen
101
provides stability in at least two ways. First, a vertical compressive force
104
is applied to the load
102
and to the turntable plate, forcing the faces of the boxes to square themselves vertically
123
. Second, the applied force
104
makes use of friction between a platen pad
105
and the load
102
to create a restrictive force
125
, which keeps the boxes
110
from sliding away from a center of rotation
140
of the load
102
.
There are at least two problems common to all wrapping devices which use a conventional top platen. The first, illustrated in
FIG. 4A
, is that the top platen arm frame
111
, shaft
112
, or platen mast or frame
113
can be manufactured out of square or can flex, causing the rotational axis
149
of the platen pad
105
to be out of square and thus misaligned or unaligned with the center of rotation
140
of the load
102
. The second and more serious problem, illustrated in
FIG. 4B
, is that the rotational axis
149
of the top platen pad
105
is fixed, passing through the geometric center or longitudinal axis of the shaft and platen pad of the top platen. Almost always, this means that the rotational axis
149
of the platen pad
105
is in a different location than the center of rotation
140
of the top of the load
102
. The top platen pad
105
can be adjusted so its rotational axis
149
will closely match the load center of rotation
140
at some vertical position. But as shown in
FIG. 10
, the center of rotation
140
of the top of load
102
may be at a different position with respect to the rotational axis
149
of the top platen
105
for loads of different heights as seen at points A, B, and C. Wear or tolerance in the manufacturing of the turntable
122
may result in an uneven turntable surface, thus affecting the location of the center of rotation of the turntable and ultimately the center of rotation
140
of the load
102
. Thus, when the vertical position of the top of the load changes, i.e., a short load is wrapped after a tall load is wrapped, the rotational axis
149
of the platen pad
105
may not be aligned with the center of rotation
140
of the top of the load
102
.
These problems exist with all conventional top platens, regardless of whether the load or the wrapping device rotates. The problem involving the center of rotation
140
of the top of the load
102
and the rotational axis
149
of the platen pad
105
can create several undesirable effects. One of the more serious effects is that as the top of the load rotates about a different center
140
than the platen pad's rotational axis
149
, the platen pad
105
and the load
102
will grind against each other. This grinding may cause wrapping material
103
placed between the load
102
and the platen pad
105
to rip, tear, or be ground away. Additionally, the load
102
itself may be affected. Loads comprised of tightly packed together units such as bricks or boxes
110
, for example, may shift and move as a result of the grinding. The shifted units
110
may create open spaces in what was a tightly packed load. If the rotational axis
149
of the platen pad
105
and the rotational center of the load
140
are sufficiently misaligned, units
110
may shift and fall off of the load
102
. If the rotational axis
149
of the platen pad
105
is not aligned with the center of rotation
140
of the top of the load
102
, the platen device
101
may make the load
102
more unstable instead of providing stability to the load
102
due to grinding, wobbling, or pushing the load
102
out during rotation caused by misalignment.
As shown in
FIG. 10
, in conventional stretch wrapping devices with turntables
122
, when the rotational axis
149
of the platen pad
105
and the center of rotation
140
of the turntable
122
are out of alignment, the amount of misalignment between the rotational axis
149
of the platen pad
105
and the center of rotation
140
of the top of the load
102
depends on the height of the load, where more misalignment is found with taller loads. For example, when a 90 inch high load with a center of rotation
140
of the turntable
122
is {fraction (1/16)} of an inch misaligned from the rotational axis
149
of the platen pad
105
, the rotational axis
149
of the platen pad
105
and the center of rotation
140
of the top of the load
102
may be misaligned by as much as ⅝ inch. Similarly 1° of misalignment at the bottom of the load
102
may create a misalignment of 3 or 4 inches at the top of the load
102
. A misalignment of ½ inch is enough to create unwanted grinding between the load
102
and the platen pad
105
.
Conventionally, alignment techniques such as the use of a plumb bob may permit alignment of rotational axis
149
of the platen pad
105
and the center of rotation
140
of a load
102
of a given height. However, this and other similar alignment techniques are cumbersome and take time. The alignment of the rotational axis
149
of platen pad
105
and center of rotation
140
of load
102
must be recalibrated each time a load of a different height is used. Even when the same height of load is used, periodic recalibration is required due mechanical wear and flexing of machine parts.
SUMMARY OF THE INVENTION
In light of these problems, it is desirable to provide a top platen capable of aligning its center of rotation with a center of rotation of the top of a load in order to stabilize the load during wrapping.
The advantages and purpose of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
To achieve the advantages and in accordance with the purposes of th
Lantech Management Corp.
Sipos John
LandOfFree
Method and apparatus for stretch wrapping a load, including... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for stretch wrapping a load, including..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for stretch wrapping a load, including... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3022888