U.S. patent number 3,861,529 [Application Number 05/331,701] was granted by the patent office on 1975-01-21 for package and method of making.
This patent grant is currently assigned to Picker Corporation. Invention is credited to Eugene W. Coleman.
United States Patent |
3,861,529 |
Coleman |
January 21, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
PACKAGE AND METHOD OF MAKING
Abstract
A skin package with a plastic base sheet and a method of making
it, the base sheet has projections and recesses therebetween. A
heat-softened cover sheet is forced down over a product and brought
into engagement with the base sheet by establishing a pressure
differential. The projections are partially collapsed inwardly to
form concavities and portions of the cover sheet enter into tight
intimate contact with the concavities. The base sheet is formed by
establishing a pressure differential while the sheet is heat
softened and on a perforated platen of a skin packaging machine.
There the base sheet is inverted so that those portions of the
sheet which have been drawn into the perforations provide the
projections.
Inventors: |
Coleman; Eugene W. (Richmond
Heights, OH) |
Assignee: |
Picker Corporation (Cleveland,
OH)
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Family
ID: |
26769856 |
Appl.
No.: |
05/331,701 |
Filed: |
February 12, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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83891 |
Oct 16, 1970 |
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Current U.S.
Class: |
206/471; 53/427;
53/433; 428/34; 428/14; 428/69 |
Current CPC
Class: |
B29C
51/10 (20130101); B65D 75/305 (20130101); B29C
51/12 (20130101); B29L 2031/712 (20130101); Y10T
428/231 (20150115) |
Current International
Class: |
B29C
51/00 (20060101); B29C 51/12 (20060101); B29C
51/10 (20060101); B65D 75/28 (20060101); B65D
75/30 (20060101); B65d 073/00 (); B32b
003/30 () |
Field of
Search: |
;206/8A,78B,471
;161/130 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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784,503 |
|
Oct 1957 |
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GB |
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550,534 |
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Jan 1943 |
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GB |
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Primary Examiner: Summer; Leonard
Attorney, Agent or Firm: Watts, Hoffmann, Fisher &
Heinke Co.
Parent Case Text
This is a continuation of application Ser. No. 83,891, filed Oct.
26, 1970, now abandoned.
Claims
What is claimed is:
1. A package comprising first and second substantially imperforate
thermoplastic sheets extending into contact in regions around an
object interposed between said sheets, said first sheet having
formations thermoformed from the material of the sheet, extending
out of the plane of the sheet toward and into contact with the
other sheet in regions around said object, and at least some of
said projections of the first sheet being partially collapsed to
form a generally cylindrical upstanding wall portion merging into a
concavity, and said second sheet having thermoformed portions
extending into firm intimate contact with the extending and
partially collapsed portions of the projections of said first sheet
to provide a firm connection between said sheets in regions around
said object.
2. A package as set forth in claim 1 wherein the connection between
said sheets includes a heat seal in a peripheral region about said
object.
3. A package as set forth in claim 1 wherein the said sheets are
thermoplastically bonded in a continuous path around said object,
forming an hermetic seal.
4. A package comprising first and second substantially imperforate
sheets extending into contact in regions around an object
interposed between said sheets, each of said sheets having
formations thermoformed from the material of the sheet and
extending out of the plane of their respective sheet toward and
into mating supporting contact with thermoformed formations on the
other sheet in regions around said object to secure said sheets
together in regions around said object, each of said sheets having
a substantially uniform thickness in regions between said
thermoformed formations, said thermoformed formations of at least
said first sheet having portions of a lesser thickness than their
respective adjacent sheet regions and extending toward the second
sheet, the tips of at least some of said projections of the first
sheet being collapsed and at least some of said thermoformed
formations on said second sheet extend into firm intimate contact
with the extending and the collapsed portions of the projections of
said first sheet to provide a firm connection between said
sheets.
5. A package as set forth in claim 4 wherein the connection between
said sheets includes a heat seal in a peripheral region about said
object.
6. A package as set forth in claim 4 wherein the said sheets are
thermoplastically bonded in a continuous path around said object,
forming an hermetic seal.
7. A skin package comprising:
a. a base sheet formed of plastic film material;
b. a first cover sheet of plastic film material;
c. a first object interposed between said base and first cover
sheets;
d. said base sheet having a plurality of projections extending
toward and into intimate engagement with said first cover sheet in
an area around said first object such that said first cover sheet
and said projections are in tight intimate contact and said base
and first cover sheets are secured together around said first
object;
e. said first cover sheet having portions extending perimetrically
of said base sheet and projections are formed in said first cover
sheet portions, said first cover sheet projections extending
oppositely from the direction of said base sheet projections;
and
f. a second object is secured to said base sheet by a second cover
sheet overlying said second object and in tight intimate engagement
with said first cover sheet projections.
8. A package comprising:
a. base sheet of substantially imperforate plastic film
material;
b. an object positioned on said base sheet;
c. a cover sheet of plastic film material overlying said object and
overlying portions of said base sheet around said object;
d. a plurality of projections formed on said base sheet extending
toward and into intimate engagement with said cover sheet and
arranged in groups in an area around said object, with smooth areas
free of projections surrounding each of said groups of
projections;
e. at least some of said projections each defining a depression
which is concave away from said cover sheet; and,
f. said cover sheet having portions which extend at least partially
inwardly of at least some of said depressions.
9. A package comprising:
a. a base sheet of substantially imperforate material;
b. a first object positioned on one side of said base sheet;
c. a first cover sheet overlying said first object and portions of
said base sheet;
d. a second object positioned on the other side of said base
sheet;
e. a second cover sheet overlying said second object and portions
of said base sheet;
f. both of said cover sheets having portions which extend
perimetrically of said base sheet;
g. said base sheet having a plurality of projections formed thereon
extending toward and into intimate engagement with at least one of
said cover sheets in an area around its associated object;
h. at least some of said projections defining a depression which is
concave away from said one cover sheet;
i. said one cover sheet having portions which extend at least
partially inwardly of at least some of said depressions;
j. the perimetrically extending portions of one of said cover
sheets having a plurality of projections formed thereon extending
toward and into intimate engagement with at least some of the
perimetrically extending portions of the other of said cover
sheets;
k. at least some of said last-mentioned projections defining
depressions that are concave away from said perimetrically
extending portions of said other cover sheet; and,
l. said perimetrically extending portions of said other cover sheet
having portions which extend at least partially inwardly of said
last-mentioned depressions.
10. A package comprising:
a. a base sheet of substantially imperforate material;
b. a first cover sheet overlying said base sheet;
c. a first object interposed between said first cover sheet and
said base sheet;
d. said base sheet having a plurality of projections formed thereon
extending toward and into intimate engagement with said first cover
sheet in an area around said first object;
e. at least some said projections defining a depression which is
concave away from said first cover sheet;
f. said first cover sheet having portions which extend at least
partially inwardly of some of said depressions;
g. a second cover sheet overlying one of said sheets encompassing
said first object;
h. a second object interposed between said second cover sheet and
said one sheet; and,
i. said second cover sheet having portions which substantially
conform to the configuration of said one sheet in at least some of
said regions of intimate engagement between said sheets
encompassing said first object.
11. The package of claim 10 wherein said second cover sheet
overlies said first cover sheet, and said second cover sheet
portions have portions which extend at least partially inwardly of
the dimples formed in said first cover sheet where said first cover
sheet extends inwardly of said depressions.
12. The package of claim 10 wherein:
a. said second cover sheet overlies said base sheet;
b. both of said cover sheets have portions which extend
perimetrically of said base sheet;
c. the perimetrically extending portions of one of said cover
sheets having a plurality of projections formed thereon extending
toward and into intimate engagement with at least some of the
perimetrically extending portions of the other of said cover
sheets;
d. at least some of said last-mentioned projections defining a
depression which is concave away from said perimetrically extending
portions of said other cover sheet; and
e. said perimetrically extending portions of said other cover sheet
having portions which extend at least partially inwardly of said
depressions.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of securing a body between two
imperforate sheets and more particularly in its preferred form to a
method of skin packaging and a skin package formed by the
method.
2. Prior Art
So-called skin packages have now become well known in the art. With
the typical skin package, a permeable base sheet is provided. With
one form of skin packaging, a surface of the base sheet has been
coated with an adhesive and the adhesive then perforated to provide
a permeable layer.
This sheet is positioned over a vacuum chamber with the adhesive
side up. The product to be packaged is positioned on the
adhesive-treated surface. A film of thermoplastic material is then
heat softened and brought down over the product and the sheet. The
vacuum chamber is operated to establish a pressure differential
such that the thermosoftened sheet is forced down over the product
into an intimate, bonded contact with the adhesive surface of the
base sheet.
In other forms of skin packaging, adhesive is not applied to the
base sheet, but rather a treated film which will become adhesively
secured to the base sheet is utilized. When the film is heat
softened and forced into contact with the sheet through pressure
differential, it bonds to the sheet around the product being
packaged.
There have been proposals for providing selected imperforate areas
in the base sheet. For example, when packaging a soft product, it
has beeen proposed to provide a protective ring around the product
and position the product on an imperforate area. When the plastic
film is forced down against the base sheet, it adheres around the
protective ring but is not drawn down into the ring and against the
soft product. While there have been such proposals, formation of
the package has nonetheless relied upon the permeability of the
base sheet.
SUMMARY OF THE PRESENT INVENTION
The present invention is directed to a novel and improved process
and package in which an imperforate plastic base sheet is used in
skin packaging. The finished package is all plastic, having a
number of advantages, many of which will be described.
It has been discovered that with an imperforate base sheet having
projections and recesses therebetween, a skin package can be
achieved with an otherwise more or less conventional process. The
product is positioned on the formed sheet and a pressure
differential is established. The heat softened film is brought down
over the sheet. Air entrapped between the film and the sheet
escapes through recesses between the projections as the established
pressure differential forces the film into tight intimate contact
with the substrate. It is believed that the escaping, flowing air
serves to maintain the film and base sheet in spaced relationship
while, at the same time, assisting in permitting the establishment
of an appropriate pressure differential.
With the present invention, the base sheet is formed so that it has
a series of projections and recesses therebetween. Preferably, the
forming of the base sheet is achieved by thermoforming. This
thermoforming of the base sheet can be accomplished with a standard
skin packaging machine set up in a manner akin to the manner
utilized when blister packages are formed. Specifically, a mold may
be formed with air holes drilled through it. A plastic sheet is
placed over the mold and heat softened. A pressure differential is
then established to draw the plastic sheet against the mold and to
cause it to achieve the contour of the mold.
In its simplest and preferred form, a "dimpled" base sheet is
formed by placing a plastic film on the platen of a skin packaging
machine. The film is heat softened and vacuum is applied so that
the platen itself serves as the mold. After formation, the base
sheet is inverted and used as a base sheet for forming a skin
package.
In addition to the many characteristics which make the packages
made in accordance with this invention superior packages for many
applications, there are considerable economic advantages over
conventional skin packages. These include:
1. The plastic film used as the base film is less expensive than
permeable card stock conventionally employed. It especially has
economic advantages over coated and perforated card stock commonly
used in making skin packages;
2. Any good-quality polyethylene film, or similar plastic material,
can be employed. Specially-treated films are not required for this
package. Thus, the plastic film used for both the base and the
covering of the package is less expensive than the base and the
film used in conventional packages; and,
3. Inventory requirements are reduced since the same material is
used for both the base and the covering sheets.
As previously suggested, the package has a number of advantages
over prior packages. One advantage is achieved when the base film
is used in its simplest form; that is, the desired form where the
film is simply formed by using the platen of a conventional skin
packaging machine. This one advantage is that the projecting
dimples on the base sheet tend to retain circular and spherical
products in place. That is, the dimples inhibit rolling when
circular products are positioned on the base sheet for
packaging.
Another advantage of all forms of the invention is that, unlike
card stock, the flexible base sheet conforms to the platen before
pressure is applied. Thus, the base sheet does not tend to be drawn
out of shape when the vacuum system is placed in operation.
In many applications, it is desirable that the base sheet not be
dimpled across its entire surface. For example, if one wishes to be
able to see the part clearly from either side of the package, it
may be desirable to have a flat, non-dimpled area in the base
sheet. This is conveniently accomplished by placing flat inserts at
various locations on the platen before the base sheet is formed.
When heat-softened film is forced down against the platen, a small
pocket is formed at each insert location. Preferably, these flat
metal inserts will be magnetic so that they will remain where
positioned on the platen and a series of identical base sheets can
be formed.
If metal inserts are made to the contour of parts to be packaged,
the formation of a base sheet for such applications as a kit for
repair parts is greatly facilitated. The person placing the parts
on the base sheet before the package is formed can make sure that a
part of the contour of each formed pocket is placed in each pocket.
Thus, formation of a complete kit and inspection to be sure that a
given kit is complete, is greatly facilitated.
If an insert, such as a thin metal sheet having evenly spaced
holes, for example about one-half inch in diameter, is used other
advantages can be achieved. When a base sheet is formed over such
an insert, it will have a series of circular dimpled areas of
one-half inch diameter. These provide selective areas of cover film
to base sheet adherence and also provide cushioning over a part for
protection of the part. Obviously, an insert with spaced one-half
inch holes is only by way of example. Such an insert between a base
sheet and the platen can take any of many varied forms.
Another advantage of the present invention is that multiple-layered
skin packages can be formed. After a first product has been skin
packaged in place, one may simply place a second product on top of
the first and then apply another layer of film. This second layer
of covering film will adhere to the first, because the first has
taken on a dimpled contour of the base sheet in that area where
they are bonded together.
Another manner of making multiple parts packages is to use a small
base sheet and package a first part with a covering film that
extends beyond the small base sheet. The covering film is then
trimmed to dimensions slightly larger than the base sheet and the
package inverted for packaging of a second part.
The band of film from the first package projecting beyond the base
sheet becomes a base sheet for a second covering film once the
package is inverted. This can be repeated any number of times, with
the package becoming slightly larger in width and height as well as
thickness each time a part is added.
In another form of the invention, if the insert extends to an edge
of the base sheet, and in fact is again used on top of the base
sheet after it has been formed and inverted, the base sheet and
film can be adhered together around three edges. This leaves the
fourth edge open to provide an inexpensive, but functional
envelope.
Another advantage of skin packages made in accordance with this
invention is the finished package is quite flexible. Accordingly, a
package containing a number of parts can be rolled and, for
example, inserted in a mailing tube for shipment or storage.
The same technique and equipment can be used to form blister
packages. One simply places inserts on the platen to the shape of
the blisters which are to be formed and then thermoforms plastic
sheet material, as distinguished from film, onto the platen. The
formed blisters can be easily closed with a skin packaging
technique or by bonding a suitable closure to them.
Other objects and a fuller understanding of the invention may be
had by referring to the following description and claims taken in
conjunction with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a skin packaging machine with
portions thereof broken away and with a base sheet positioned to be
formed;
FIG. 2 is a similar schematic view of a skin packaging machine with
portions thereof broken away and showing a formed base sheet
positioned for forming a package, a product in place, and a
covering film held by a drape frame;
FIG. 3 is an enlarged fragmentary sectional view of the finished
package;
FIG. 4 is a plan view of a package;
FIG. 5 is an enlarged fragmentary sectional view of one form of
multiple parts package where the parts are packaged sequentially
rather than simultaneously;
FIG. 6 is an enlarged, fragmentary view of another form of package
with multiple parts that have been sequentially packaged; and,
FIG. 7 is a fragmentary plan view of a package in which projections
have been formed in spaced selected areas.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings and to FIGS. 1 and 2 in particular, a
skin packaging machine is shown schematically at 10. Since the skin
packaging machine itself is conventional, it is shown only
schematically. A suitable, commercially-available skin packaging
machine for performing the process and making the package of this
invention is a Model 200 series vacuum packaging machine sold under
the trademarks AMPAK and PORT-A-VAC by American Packaging
Corporation of Hudson, Ohio.
The packaging machine 10 includes a platen 11. The platen 11
typically is a perforated sheet of steel having uniformly disposed
perforations. Typically, the perforations may be of the order of
one thirty-second inch in diameter and they will be spaced of the
order of one-eighth inch from center to center. There will be of
the order of 75 holes per square inch.
The machine 10 includes a vacuum chamber 12 below the platen 11.
The vacuum chamber 12 is evacuated by a suitable vacuum source such
as a vacuum pump 13. An oven is above the platen 11 and is
represented by a schematic showing at 15 of a heater element.
The commercial machine is slightly modified in that a bleed line
and bleed valve 14 are provided. The valve is adjusted to draw air
through the line as well as through the platen 11 when it is
desired to reduce the platen vacuum.
A drape frame is shown at 16. The drape frame holds a covering film
adjacent the heat 15 until the film is heat softened. The drape
frame is then lowered to position the film for formation of a
package.
Referring now to FIG. 1, a sheet of plastic film to be formed into
a base sheet is shown at 19. An insert 20 is mounted on the platen
so that an area 21 will be free of dimples in the finished base
sheet 19. As has been suggested previously, in its simplest form,
the insert 20 is not employed. Conversely, where desired, a series
of inserts 20 may be used but for clarity of illustration, only one
is shown in FIG. 1. Similarly, for clarity of illustration, the
thickness of the insert 20 and of the plastic film 19 is greatly
exaggerated in the drawings.
When the base sheet is formed, the drape frame need not contain a
film. The oven, represented by the heater 15, is energized to
thermosoften the base film 19. The vacuum pump 13 is then operated
to draw the film tightly down against the insert 20 and the platen
11. A smooth pocket is formed over the insert 21. The vacuum draws
portions of the film 19 in a dimpled area 22 into the holes in the
platen. The vacuum preferably is not sufficiently high to cause the
film to rupture as it is forced into the platen apertures. For this
purpose, the vacuum may be adjusted by adjusting the bleed valve
14.
When film in the dimpled area 22 is drawn against the platen, a
series of projections or dimples are formed by the portions drawn
into the platen perforations. The spaces between these dimples or
projections are smooth surfaces where the film has been drawn
against the platen. These smooth surfaces form recesses between the
projections.
After the base sheet has been formed in the manner shown and
described in connection with FIG. 1, it is stripped from the platen
and inverted so that the projections extend upwardly as depicted in
FIG. 2. A body 24, which may be a part or other object such as a
washer, is positioned on the pocket 21 of the inverted base sheet
19.
A covering film 25 is positioned in the drape frame and adjacent
the heater 15 for thermosoftening. After the covering film 25 has
been thermosoftened, the drape frame 16 is lowered to a position
near the platen 11. The vacuum pump 13 is then operated to
establish a pressure differential. Since the base film 19 is
imperforate, the vacuum pump 13 serves to establish a volume of
reduced pressure between the base film 19 and the covering film 25
by withdrawing air from around the perimeter of the base film
19.
It should also be noted that many plastic films are not truly
imperforate. Moreover, the small projections may rupture when
burned but the holes thus formed are small and do not adversely
affect the formation of the novel package. As used here, the term
"imperforate" as applied to the substrate or base sheet 19, is
intended to mean sufficiently imperforate to a flow of air at the
pressure differentials which are established in skin packaging when
a vacuum system is operating so that the package is formed
primarily by withdrawing air from around the perimeter of the base
sheet rather than through it.
Establishment of the described volume of reduced pressure between
the base and covering films 19, 25 establishes a pressure
differential on the covering film 25. This forces the heat softened
covering film 25 down over the body 24 and against the base film
19. As the covering film 25 approaches the base film, entrapped air
moves radially outwardly from the center of the package in all
directions. This establishes a flow of air around the projections
and through the recesses defined by the projections in the base
film 19. This flow of air apparently keeps the two films apart
until the air is exhausted adequately to achieve a tight physical
contact and a mechanical bond, i.e., a mating or nesting of film
portions with like contours in intimate contact, in the dimpled
area 22.
By appropriate selection of films and temperature control, the
mechanical bond can be enhanced by a physical bonding to produce a
hermetically sealed package. If the bond is only mechanical,
obviously the package is readily openable by simply separating the
films near the perimeter and pulling. With a physical bond or
so-called heat seal, caused by heat softening and forcing the two
films together, complete hermetic protection is obtainable.
As an example of how to obtain a bond which is primarily, if not
exclusively, only mechanical, it has been found that one may use
polyethylene film of 4 to 10 mils thickness for both the base and
covering film or sheets. When the package is formed, the
temperature and length of time vacuum is applied is relatively
short.
Where a physical bond as well as a mechanical bond is used, it has
been found that a simple elevation in covering film temperature of
a few degrees and maintaining vacuum for longer times will
accomplish the desired result.
The temperatures and vacuum time durations vary according to films
being used. One simply increases the heat and vacuum cycles if a
mechanical bond is being obtained and a physical bond is desired
and vice versa.
Referring now to FIG. 3, an enlarged fragmentary sectional view is
shown of a package. There the plastic thickness is greatly
exaggerated for clarity. An examination of FIG. 3 will show that
after package formation, dimple top 27A has become concave and the
covering film 25 has been drawn down snugly over the product and,
in addition, into tight intimate physical contact with and into the
dimples 27. The cover sheet remains spaced from the recesses 28
between the dimples.
In FIG. 4, a sample parts kit package has been shown at 30. For
simplicity of illustration, the parts kit has been shown as a nut
and bolt 31, 32 and a washer 33. A hex-shaped insert was used to
provide a pocket for the nut 31, a T-shaped insert for the bolt 32,
and a circular insert for the washer 33.
It can be seen that the balance of the package around each of these
three parts is dimpled and the covering film has been brought into
tight contact and connection with the base sheet.
In FIG. 5, a base sheet 35 was first formed. A product 36 was then
packaged to the base sheet by a first covering sheet 37. The first
covering sheet 37 extends perimetrally outwardly from the base
sheet 35 and dimples have been formed in a perimetral portion 39.
The package was then inverted and this perimetral portion 39 became
the base sheet for a second part 40 and a second covering sheet 41.
The second covering sheet 41 includes a perimetral part 42 which
may serve as the base sheet for a third part if that is desired.
Thus, one may simply invert the package of FIG. 5, place yet
another part on top of the first base sheet 37 and form a package
by drawing another covering sheet, this time into engagement with
the perimetral base part 42.
The projections in the perimetral base part 42 are dome shaped.
That is, each projection includes a frustoconical side wall 43 and
a convex top 45. By contrast, the tops of other projections in the
drawings are accurately shown as convex. The reason is that the
initially concave projections become concave at the time when
pressure is applied to connect a cover sheet to a base sheet.
It will also be seen that the walls of the projections 42 taper
from a relatively thick base adjacent recesses 46 to the apex of
the top 45.
In FIG. 6 a second covering sheet 50 secures a second part 51 to a
package like the package of FIG. 3 but for a small difference in
the base sheet 19'. The difference is that no insert was used in
forming the base sheet 19' and the projections are under the object
24. The projections are shown without tops as may occur in their
formation. The package of FIG. 6 was formed simply by positioning
the second product 51 on the package of FIG. 3 while it is on the
platen 11 and then establishing a pressure differential to draw the
thermosoftened second cover sheet 50 into place.
In FIG. 7, the projections are arranged in groups 47. The groups 47
are surrounded by flat areas 48. The covering sheet is drawn into
tight intimate contact with the flat areas 48 of the base
sheet.
Although the invention has been described in its preferred form
with a certain degree of particularity, it is understood that the
present disclosure of the preferred form has been made by way of
example and that numerous changes in the details of construction
and the combination and arrangement of parts may be resorted to
without departing from the spirit and the scope of the invention as
hereinafter claimed.
* * * * *