Note: Descriptions are shown in the official language in which they were submitted.
2033675
STRETCH-WRAP FILM DIS~N~:K
BACKGROUND OF THE l~v~.~lON
This invention relates to the field of stretch-wrap film
packaging, in particular to a tool for dispensing highly
stretchable plastic film for use in packaging.
The development of the stretch film wrap industry has brought
about a need for devices capable of paying out film under variable
tension as it is wrapped around a package or object or group of
objects to be packaged together. Typically, such stretch-wrap film
is supplied in rolls wound around a hollow core, and the film is
unwound from the roll as it is applied. It is necessary as the
film is unwound to apply a degree of tension to the unwinding end
of the film so that the film will be somewhat stretched as it comes
into contact with the object being packaged. For various reasons,
it is desirable that the operator be easily able to control the
degree of tension applied.
A number of such devices are already known. United States
Patents 4,179,081 and 4,248,392 issued December 18, 1979 and
February, 1981, respectively, to John C. Parry disclose devices
with a flexible hand grip that is squeezed to exert a braking force
to the core of a roll of film, whereby the operator may control the
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amount of tension on the film as it unrolls by varying the
magnitude of pressure on the hand grip. These devices work
particularly well with wider film rolls of 10 inches or greater
with one such device at either end of the roll.
Tools for dispensing narrower stretch-wrap films, for example,
those from one to five inches wide have also been made. With such
narrower films, one-handed operation is often possible and more
convenient. The Parry devices disclosed in the above-mentioned
patents may be used for one-handed operation, but it has been found
lo that the twisting torque resulting from one-handed operation may
cause binding between the roll core and the hand grip, and a degree
of loss of control of the tension.
United States Patent 4,722,493 issued February, 1988 to Daniel
J. Parry and John C. Parry discloses a device which uses the type
of hand grip as discussed above and is well suited for one-handed
operation. In this device, the roll core is engaged by a spindle
which is freely rotatable with respect to a cylindrical handle.
The flexible hand grip covers the handle and a collar attached to
the spindle. With free rotation between the spindle and the
handle, binding is avoided because the handle turns with the hand
grip. Braking force is applied by the thumb and forefinger against
the collar. It has been found, however, that in extended use with
this type of arrangement the thumb and forefinger may become
fatigued, resulting in a temporary impairment of ability to control
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the application of tension to the film.
United States Patent 4,834,312 issued May 30, 1989 to Paul K.
Riemenschneider discloses a dispenser wherein a head is affixed to
a roll of film and a spindle extends from the head. A split
cylinder forms a grip surrounding the spindle, and may be squeezed
to exert frictional braking pressure. However, because the braking
force is applied generally along the length of the spindle, this
dispenser also tends to bind as a result of the twisting torque
which results from one-handed operation.
Other more elaborate dispensers have also been made. It is
desirable, however, that such devices be of simple, lightweight and
inexpensive construction. In practice, such tools are easily lost
or destroyed and through extensive use may require relatively
frequent replacement. Lightness of weight is desirable to enable
constant use without unnecessary expenditure of energy and
resultant fatigue.
8UMMARY OF THE lNv~ lON
The present invention is a simplified improvement over the
dispenser disclosed in United States Patent 4,722,493, which may be
constructed of inexpensive lightweight materials, easily
manufactured and assembled. When in use, the subject simplified
dispenser utilizes a drum brake principle similar to that of the
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dispenser of Patent No. 4,722,493. In the dispenser of the
present invention, bearings are used to eliminate the problem of
binding, and such bearings may be arranged so that the radial
force on the drum brake may be applied through the middle
fingers and palm of the hand, avoiding the fatigue resulting if
the force always originates from the thumb and forefinger.
The invention is directed to a dispenser for a roll having
a core around which is wound a quantity of stretch-wrap film.
The dispenser comprises: a spindle having a substantially
cylindrical shaft and an integral hub at one of the shaft, said
hub being adapted for insertion into the core of the film roll
and having means thereon for preventing relative rotation
between the core and the hub; a first sleeve bearing mounted
coaxially upon the shaft adjacent said hub, and freely rotatable
upon the shaft; a brake drum mounted coaxially upon the shaft
with one end longitudinally adjacent the first sleeve bearing;
means constraining the brake drum to rotate in unison with said
shaft; a second sleeve bearing mounted coaxially upon the shaft
longitudinally adjacent the other end of said brake drum, said
second sleeve bearing being freely rotatable upon the shaft; and
a single flexible hand grip having a tubular portion surrounding
both of said sleeve bearings and said brake drum, said grip,
when relaxed, being out of contact with said brake drum, but
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coming into contact with the brake drum, to resist rotation of
the spindle, when finger pressure is applied to the grip against
the brake drum, but not when finger pressure is applied to the
grip only against the sleeve bearings.
The brake drum may be a hollow cylinder rigidly secured to
the shaft.
The hand grip may comprise means for resisting longitudinal
movement of the hand grip with respect to the spindle.
The outside diameter of the sleeve bearings may be slightly
greater than the outside diameter of the brake drum.
The end portion of the spindle may be a hub of diameter
slightly larger than the inside diameter of the core of the roll
whereby the hub may be forcibly inserted into the core for
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frictional engagement therewith. The hub may have longitudinal
ridges for positive rotational engagement with the core.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a preferred
embodiment of the subject invention.
FIG. 2 is a perspective view of the spindle of the invention
with the brake drum installed thereon.
FIG. 3 is a sectional view of the dispenser of Fig. 1.
FIG. 4 is a perspective view partially cut away of the
lo dispenser shown in FIG. 3 showing the direction of rotation.
FIG. 5 is a partial sectional view of a preferred alternative
embodiment of the invention.
FIG. 6 is a partial sectional view of the dispenser shown in
FIG. 3 showing the result of applying radial force.
FIG. 7 is a perspective view of the dispenser shown in FIG. 3
showing the manner of grasping the dispenser for use.
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FIG. 8 is a partial sectional view of an alternative
embodiment of the invention.
FIG. 9 is a partial sectional view of a further alternative
embodiment of the invention.
DESCRIPTION OF THE PREFERRED ENBODIMENTS
Typically, rolls of stretch-wrap film have a rigid hollow
cylindrical core 20, as shown in FIG. 1. Such core material may be
made of cardboard which is impregnated with glue and then wound
around a removable mandrel. This core material may also be used in
the construction of the simplified dispenser of the invention.
Having reference first to FIG. 1, in the preferred embodiment,
the simplified dispenser for a roll of stretch-wrap film 10 is
constructed of a spindle 12, two bearings 14,16 preferably formed
of cardboard core material, a flexible hand grip 18, and a brake
drum 22 preferably formed of cardboard core material. The spindle
12 is preferably formed of blow molded plastics material, for
example, rigid polyethylene.
The spindle 12 has an end portion 24 and a handle portion 26,
designated generally on FIGS. 1 and 2. The end portion 24 of the
spindle 12 forms a substantially cylindrical hub 28 or plug
appropriately dimensioned for forced insertion by hand into the
fibre or paper core 20 of a roll of film. The hub 28 also has
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protruding longitudinal ridges 30 to positively engage the core 20
and resist relative rotation. For secure attachment to the core 20
of the roll, the outside diameter of the hub 28, including the
protruding ridges 30, is slightly greater than the inside diameter
of the core 20.
FIG. 2 illustrates the spindle 12 having handle portion 26
extending coaxially from the hub 28, with brake drum 22 installed
thereon, to form a middle segment 32 of a diameter suitable for
hand-gripping. A diameter of about 1~ inches has been found to be
suitable. Two other segments of handle portion 26, designated the
outer segment 34 and the inner segment 36 for the purposes of this
description, are axially adjacent to and on either side of the
middle segment 32. The outer and inner segments 34,36 are of
lesser diameter than the middle segment 32 to accommodate the
bearings 14, 16. With respect to the middle segment 32, the outer
segment 34 is on the side of the spindle opposite the roll 10, and
the inner segment 36 is on the side nearest the roll 10.
The handle portion 26 of the spindle 12 is preferably
constructed in the following manner. A cylindrical shaft 38, as
shown in FIG. 1, of substantially uniform diameter is formed as a
unit with the hub 28 or end portion, extending coaxially therefrom.
A series of longitudinal ridges or knurls 40 are formed at about
the midpoint of the shaft. A brake drum 22 of cardboard core
material is pushed onto the shaft to form the middle segment 32,
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shown in FIG. 2. The brake drum 22 has an inside diameter
substantially equal to the outside diameter of the shaft 38, or
very slightly greater, so that when the brake drum 22 is forced
onto the knurls 40 of the shaft 38, it remains in fixed coaxial
engagement with the shaft 38. Frictional forces resist
longitudinal movement of the brake drum 22 once installed on the
shaft 38.
The length of the cylindrical shaft 38 is suitable to form a
handle. About 3~ to 3~ inches has been found to be appropriate.
The middle segment 32 occupies the middle of the shaft 38, leaving
two approximately equal unoccupied segments of the shaft, adjacent
the middle segment 32, to form the outer and inner segments 34,36.
The outer and inner segments 34,36 are of lesser diameter than the
diameter of the middle segment 32, and are therefore able to accept
outer and inner bearing means 14,16 having an outside diameter
suitable for hand-gripping.
Referring now to FIGS. 1 and 3, outer and inner bearings 14,16
are formed of hollow rigid cylinders of cardboard core material,
having an inside diameter just slightly larger than the diameter of
the cylindrical shaft 38 of the handle portion 26 of the spindle
12. The outer and inner bearings 14,16 are inserted coaxially on
the shaft 38 to engage the outer and inner segments 34,36,
respectively, of the shaft 38, and rotate freely with respect to
the shaft 38. In assembling the dispenser, the inner bearing 16 is
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installed before the brake drum 22 forming the middle segment 32 is
installed.
There is a degree of choice in selecting the dimensions of the
hollow cylinders of the bearings 14, 16 and the brake drum 22.
With respect to the length of the brake drum 22 and of the inner
and outer segments 34,36 and bearings the 14,16, the length of the
brake drum 22 determines how much braking surface is available for
application of radial braking force by an operator's hand. It has
been found that in the case of high-strength three-inch wide
stretch film, a suitable ratio of braking surface to non-braking
surface is obtained, if the brake drum 22 is in the range of 11/2 to
2 inches, and the length of each of the outer and inner bearings
14,16 is in the range of ~ to 1 inch, but the dimensions of these
hollow cylinders are not limited to the aforesaid ranges. The
length of braking surface will depend upon, inter alia, the length
of the roll of stretch film and the strength of the film itself.
It is an advantage of the present, simplified construction
that whatever ratio of braking surface to non-braking surface is
chosen at the time of manufacture may subsequently be modified by
replacement of the bearings 14,16 and the brake drum 22 forming the
middle segment 32. Thus, to obtain a greater or lesser ratio of
braking surface, one may simply remove and replace the aforesaid
three hollow cylinders with differently dimensioned ones. The
selection of a preferred ratio of braking surface may depend on
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such factors as the hand strength of the operator and the width of
the film being used. Similarly, the relative lengths of the outer
and inner bearings 14,16 (and corresponding outer and inner
segments 34,36) need not be equal, but may be selected according to
the preference of the operator.
With respect to the diametrical dimensions, it is required
that the inside dimensions of the bearings 14,16 be such that the
bearings rotate freely on the shaft 38, and further that the
outside diameters of the bearings 14,16 and brake drum 22 be
lo suitable for hand-gripping. Apart from these requirements, there
is a range of latitude. It is possible, for ease of manufacture,
that the same core material be used for the bearings 14,16 and the
brake drum 22. The inner bearing 16 is forced over and beyond the
knurls 40 so as to be able to rotate freely. The hollow cylinder
22 which forms the middle segment 32 is forced onto the knurls 40
which then hold the cylinder 22 rigidly in place. The outer
bearing 14 does not pass over the knurls 40 but remains on the end
of the shaft 38 where it may rotate freely. In this arrangement,
the outside diameters of the bearings 14,16 and the brake drum 22
are equal.
In a preferred alternative arrangement, as shown in FIG. 5,
the inner bearing 16A is formed of a hollow rigid cylinder of
slightly larger inside and outside diameters than those of the
other hollow cylinders 14,22. Having a larger inside diameter
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facilitates inserting the inner bearing 16A over the knurls 40, and
similarly removing the inner bearing 16A if desired for
replacement. Having a larger outside diameter provides an improved
shoulder or seating to retain the flexible hand grip 18, as
described below. Again, operator preference may also dictate an
alternative combination of diameters.
Referring again to FIG. 1, the flexible hand grip 18 is
similar to that described in United States Patent 4,722,493. The
hand grip 18 is formed of resilient plastics material, for example,
lo polyvinyl chloride, and resembles a motorcycle hand grip. The hand
grip 18 has a sleeve 42 which is closed at one end by an end cap 44
and open at the opposite end 46. At the open end 46 is an
outwardly projecting circumferential flange 48 to protect the
operator's hand from contacting the roll, and an inwardly
projecting circumferential ridge 50.
The hand grip 18 covers the handle portion 26 of the spindle
12, the brake drum 22, and the outer and inner bearings 14,16. The
ridge 50 causes a constriction in the opening 46 of the hand grip,
which ridge 50 engages the leading or inner edge of the inner
bearing 16. This engagement resists longitudinal movement of the
hand grip 18 with respect to the spindle 12, and therefore prevents
the hand grip 18 from sliding off the handle portion 26 and
bearings 14,16. The end cap 44 prevents the outer bearing 14 from
sliding off the shaft 38.
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The ridge 50 thus functions to prevent the dispenser from
inadvertently disassembling during use. However, the ridge 50 is
not so pronounced as to prevent the hand grip 18 from being
manually installed onto and removed from the dispenser by way of
assembly and disassembly. The ridge 50 is thus dimensioned with
respect to the outside dimensions of the bearings 14,16 and brake
drum 22 so that the hand grip 18 may be installed and removed with
the application of manual force. A preferred arrangement, as shown
in FIG. 5, is that the outside diameter of the inner bearing 16A be
lo slightly greater than that of the brake drum 22 and the outer
bearing 14 to maximize the degree of positive engagement between
the ridge 50 and the inner bearing 16A without requiring
application of significant force for installation and removal of
the hand grip 18. An important advantage of the invention is that
the dispenser may be used in an upside down position i.e. with the
roll oriented downward without the dispenser disassembling.
The hand grip 18 is provided with a plurality of internal
spaced longitudinal ribs 52, so that only the tips of the ribs
engage the surface of the brake drum 22. The hand grip 18 is
dimensioned to fit somewhat loosely at least over the brake drum 22
so that the spindle 12 rotates freely with respect to the hand grip
18 as long as no radial hand pressure is applied at the surface of
the brake drum 22. If radial hand pressure is exerted on the hand
grip 18 at the surface of the brake drum 22 as shown by arrows in
FIG. 6, the ribs 52 are forced into contact with that surface.
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In use, the dispenser is securely attached to the hollow core
20 of a roll of stretch-wrap film 10 by the hub being forcibly
inserted into the core. The hub 28 is retained by frictional
forces, while the longitudinal ridges 30 dig into and positively
engage the core material and resist relative rotation. The leading
edge of the film 54 is held against or attached to the objects
being wrapped and the dispenser is moved around the objects while
the film unwinds from the roll and is transferred to the objects.
The dispenser may alternatively be held stationary and the objects
lo rotated.
As the film unwinds, the spindle 12 rotates along with the
roll 10, as shown in FIG. 4. As long as no radial hand pressure is
applied to the hand grip 18 at the surface of brake drum 22, the
spindle 12 rotates freely with respect to the hand grip 18 by
virtue of the inner and outer bearings 14,16 and the loose fit
between the hand grip 18 and the brake drum 22 of the spindle 12,
and the film unwinds easily. In this way, the film is dispensed
substantially without any linear tension on the film, and the film
does not stretch appreciably.
In order to form a secure packaging, the film is stretched
during application by applying tension on the unwinding end 54. In
order to provide such tension, the operator grips the hand grip 18
as shown in FIG. 7, and applies radial hand pressure on the hand
grip 18 at the surface of the brake drum 22 of the spindle 12. The
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~03~S7~
radial hand pressure causes the hand grip 18 to deform, as shown in
FIG. 6, and the longitudinal ribs 52 are pressed into contact with
the surface of the brake drum 22 creating frictional braking
torque, that is, tangential frictional force between the ribs 52
and inner surface of the hand grip and the surface of the middle
segment 32 which resists rotation of the spindle 12. This braking
torque is transmitted through the spindle 12 to the roll of
stretch-wrap film 10 resulting in a tangential counter force
applied at the edge of the roll of film to the unwinding end 54 of
lo the film.
Radial hand pressure applied to the hand grip 18 at the outer
and inner bearings 14,16 may cause deformation of the hand grip 18,
but no frictional force will be created because of the operation of
the bearings. As a result, a strong grasp can be applied in
retaining and using the dispenser, if required, independently of
the amount of braking force applied. Furthermore, non-braking
grasp may be applied at both ends of the hand grip, so that a
strong grasp may be applied as required to resist a significant
twisting torque without thereby increasing the braking force to an
excessive magnitude. This prevents significant binding as was
encountered in many prior art devices.
In the preferred embodiment of the invention, the braking
surface of the dispenser is at the middle of the hand grip 18. In
order to apply braking force, the operator applies radial hand
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pressure at that surface, which typically is the surface beneath
the middle two or three fingers. Braking force is thus applied
through the middle part of the hand which resists fatigue.
The central location of the braking surface provides other
options for resisting operator fatigue. Braking force may be
increased, when required, by increasing the magnitude of pressure
applied by each finger over the braking surface, or by increasing
the number of fingers over the braking surface and thereby the area
through which the braking force is applied. The operator has a
degree of latitude in arranging his grasp on the hand grip, and by
altering his grasp periodically may avoid fatiguing one particular
finger or another.
The operator also has the option of disassembling the handle
portion 26 of the spindle 12 and installing a different arrangement
of bearings and braking surface. This option may enable a
particular operator to "set" the dispenser at an optimal
arrangement for personal use, and/or to adjust the dispenser during
a pause in use to alleviate fatigue.
Alternative embodiments of the simplified dispenser may be
constructed. In one alternative embodiment, as shown in FIG. 8,
the inner bearing may be eliminated for even greater simplicity of
manufacture and construction. There is thus only a first segment
100 of the handle portion of the spindle, which forms the braking
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surface, and a second segment 102 for coaxial engagement with a
bearing means 104. The construction is otherwise similar to the
embodiment with two bearings as described earlier. In use, the
braking force is applied through the thumb and forefinger, while no
braking force is applied by the rest of the hand because of the
relative location of the bearing.
In a further alternative embodiment shown in FIG. 9, the outer
bearing has been eliminated. This alternative embodiment of the
subject dispenser comprises inner bearing 110 and braking cylinder
112. It should be appreciated, however, that the alternative
lo embodiments shown in FIG. 8 and FIG. 9, having a single bearing,
may not necessarily function as well as the preferred embodiment of
the subject dispenser having two bearings, especially during one-
handed operation.
In other embodiments (not illustrated), different types of
bearing means may be used, for example, roller bearings, or very
thin-walled hollow cylinders formed of a slippery material such as
teflon. Bearings of this latter type may be formed integrally with
the flexible hand grip.
Variations may be introduced in the mode of construction of
the dispenser described above without departing from the principle
of the invention. For example, the spindle 12 may be constructed
initially in the shape in which it appears in FIG. 2. Thus, the
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middle segment 32 of the handle portion 26 of the spindle 12 which
provides the braking surface may be formed by an enlarged, integral
part of the spindle rather than by insertion of a hollow cylinder
onto a cylindrical shaft of uniform diameter, as described above
with reference to FIG. 1 and FIG. 2. With such construction,
different methods which are known in the art such as a split ring
construction will be used to provide an inner bearing means to
engage the inner segment of the spindle. Other substitutions of
materials and of methods of construction are known and may be
lo employed.
While this dispenser has been developed primarily for
dispensing stretch-wrap film, it may equally have other uses
without departing from the principle of the invention, for example,
for dispensing adhesive tape or other web materials.
Further, while this dispenser is designed primarily for one-
handed operation with small rolls of stretch film, it can also be
used in conjunction with longer rolls of stretch film by placing
one dispenser in each end of the core of the longer roll. In such
two-handed applications, the brake drum of the subject dispenser
would normally be made longer in order to apply greater tension to
the wider film, depending upon the strength of the film. In the
case of weaker films, the braking surface should be reduced, to
prevent the film from breaking under braking force.
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203~675
Other modifications in the construction or use of the
simplified dispenser will readily occur to persons skilled in the
art. The above description is illustrative of the invention, and
a variety of modifications are possible without departing from the
scope and spirit of the following claims.
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