Automatic vacuum packaging apparatus

An automatic vacuum packaging apparatus which is defined by a closable frame having upper and lower sections, the lower section including a heatable platen configured with one of several patterns of transversing channels through which air can be evacuated through two separate conduits drawn into one vacuum chamber located beneath the lower platen. The upper section is closable over the lower section and has a separate variable heating element and separate peripheral attachment to the vacuum. Plastic sheets may be placed on the upper and lower frames, and an object placed between them. Then, through the electronically controlled interaction of the vacuum, heating elements, channels and closure of the frames the object may be vacuum sealed between the plastic sheets. The patterns of channels allow for the improved removal of air as the channels vary in length thus increasing the ability of the vacuum to efficiently remove over 97% of the air by concentrating the pull of the vacuum in smaller areas.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to vacuum packaging systems. In 
particular, this invention relates to an improved automatic method and 
apparatus for the vacuum packaging of products between two sheets of 
plastic film through the use of transverse channels and side ventilation 
panels. 
2. Description of the Prior Art 
Vacuum packaging systems are well known in the art. Early vacuum packaging 
systems such as U.S. Pat. Nos. 2,778,173; 3,255,567; 3,311,517; and 
3,216,172 each allow for vacuum sealing of an object sandwiched between 
two heated sheets of plastic material. There are drawbacks to the air 
evacuation methods of each of these patents since an opening in the vacuum 
seal is left after air is removed which opening must be separately closed 
by a subsequent operation. As a result, the vacuum closure can never be 
absolute, and there is a risk of introduction of foreign matter after the 
vacuum process has been completed. 
A U.S. Pat. No. 2,778,173 (1957) issued to Taunton discloses a vacuum 
packaging method wherein two pieces of packaging film sandwiched an 
article therebetween. One or both of the films are placed on heated dies 
which create projections on the films. The object is placed between the 
two films with the projections facing each other. A vacuum is then drawn 
through an exhausting hole extending through one film and surrounded by 
projections, thereby removing the air between the object and the two 
plastic sheets. The sheets can then be heat sealed to close the exhausting 
hole. 
U.S. Pat. Nos. 3,255,567 (1966) and 3,311,517 (1967) to Keslar et al., 
disclose a bag comprised of two 2-ply layers of plastic material which 
sandwiches the object to be sealed. The inner ply of each of the two sides 
of the bag is embossed with a grid of protuberances which provide grooves 
through which air can escape. Three sides of the bag are sealed and the 
object is placed between the two layers. The air is then removed through 
an evacuation apparatus through the open side of the bag. Once the 
evacuation is completed the open side is heat sealed. 
The Piazze invention, U.S. Pat. No. 3,216,172 (1965) shows a method and 
apparatus for sealing a vacuum packaging bag. The lower side of the bag 
has an air evacuating opening. A stiff patch is then placed over the 
opening. 
Refinements to the earlier patents described above are disclosed in U.S. 
Pat. Nos. 3,828,520 and 3,945,172. Both of these patents were based on the 
use of ridges on a lower platen (or preformed lower plastic sheet) which 
created additional channels through which is evacuated. U.S. Pat. No. 
3,828,520 issued to Merritt in 1974 discloses a method of producing an 
airtight sealed package through the use of a lower platen with raised 
protuberances which allowed for the removal of air through the channels 
created by the protuberances. In U.S. Pat. No. 3,945,172 (1975) issued to 
Johnson, this method was improved upon through the use of a preformed 
bottom plastic sheet. The preformed bottom plastic sheet provided 
transverse channels through which air was drawn to assure complete 
exhaustion of air between the top and bottom sheets. Despite the 
introduction and use of the additional channels in the lower platen or 
sheet, these inventions only resulted in an air evacuation rate of between 
50% and 60% percent. 
SUMMARY OF THE INVENTION 
The present invention improves on the prior art by introducing an automatic 
vacuum sealing apparatus having either two or four side ventilation panels 
through which air is evacuated thereby creating a much improved vacuum 
seal around an object. The present invention provides an air evacuation 
rate between 97-99% through the use of a minimum of 23-30 Hg of vacuum 
power. In one embodiment of the present invention, a special 4-sectioned 
platen (see FIG. 4) is provided having grooves, channels and openings 
therein (as well as four air troughs along its sides) which provides for 
extremely efficient air evacuation from around an object. 
It is therefore a primary object of the present invention to provide an 
improved automatic vacuum packaging and sealing method and apparatus which 
allows for the removal of substantially all air around a packaged object 
by means of a bottom platen having side rail air evacuation channels which 
eliminate the need for a subsequent operation. 
It is another important object of the present invention to provide an 
improved method for creating an airtight package comprised of two sheets 
of mutually exclusive.sup.1 self-adhering nonporous plastic film utilizing 
an improved lower platen which provides for the removal of air through a 
bottom platen and side rail channels. 
FNT .sup.1 The sheets will only adhere to themselves and not to any other 
object including the object being packaged. 
Another object of the invention is to provide an improved heated vacuum 
platen that is capable of removing air from its upper surface as heat is 
applied thereto in order to deform a sheet of plastic film into the shape 
of the platen while also removing air from the sides of the deformed sheet 
in order to seal an object. 
Another object of the invention is to provide an improved heated vacuum 
platen having a pattern of four triangular sections thereon and four 
corresponding air-removal troughs for efficiently removing air from within 
the plastic film around an object. 
Another object of the invention is to provide a Programmable Logic 
Controller which adjusts the heat, vacuum force and timing of the sealing 
operation to allow for variance in these elements in order to respond to 
varying thicknesses of plastic employed and the size of the object sealed. 
Another object of this invention is to create a superior durable, speedy 
and efficient automatic vacuum packaging apparatus which is not labor 
intensive and is simple to operate. 
Other and further objects of the invention will become apparent through the 
following descriptions and accompanying drawings. 
It has been found that the foregoing objects may be attained through the 
use of an automatically controlled closable frame having upper and lower 
sections, the lower section including a heatable platen configured with 
one of several patterns of transversing channels through which air can be 
evacuated through two separate conduits drawn into one vacuum chamber 
located beneath the lower platen, the upper section being closable over 
the lower section and having a separate variable heating means and 
separate peripheral attachment to the vacuum. The lower platen is 
comprised of a heatable pattern of ridges and openings (blades) which 
create channels through which air can be drawn into a chamber below the 
lower platen connected to a vacuum pump. The configuration of the blades 
allows for the improved removal of air as the channels vary in length thus 
increasing the ability of the vacuum to efficiently remove air by 
concentrating the pull of the vacuum in smaller areas. In addition to the 
channels created by the blades, separate side channels are also a feature 
of the lower platen. These side channels lead to a separate conduit 
through which air is also removed by means of the vacuum located beneath 
the lower platen. Both the upper and lower platen have their own automated 
heating elements. 
In order to seal an object, two separate sheets of self-adhering plastic 
are used. The first sheet is loaded onto the underneath the movable upper 
mounting frame and held in place by activation of the peripheral vacuum. 
Thereafter, the upper heating element is activated causing the plastic to 
bow downwards in the middle (see FIG. 7A). A second plastic sheet is 
placed on the lower platen and the lower heating element is activated in 
order to make the second plastic sheet deformable. The lower vacuum is 
then activated pulling air through the holes in the lower platen, causing 
the second plastic sheet to deform into the pattern of the lower platen. 
The product to be sealed is placed on top of the deformed second plastic 
sheet. The upper frame is then lowered over the lower platen so that the 
bowed portion of the first plastic sheet comes into contact with the 
object being packaged. The side air channels located in the lower platen 
are then activated causing air to be removed through the deformed channels 
in the lower plastic sheet from all four sides of the lower platen. This 
causes the first (upper) plastic sheet to be pulled down tightly over the 
object. The side suction is shunted at increasing timed intervals in order 
to remove as much air as possible. Finally, the peripheral vacuum to the 
upper platen is turned off, freeing the heated first sheet of plastic so 
that its edges may be adhered to the edges of the second sheet of plastic. 
Those portions of the upper sheet of plastic which are not in contact with 
the object adhere to the tops of the ridges of the deformed lower sheet. 
As the last air is removed, the two plastic sheets adhere to each other, 
sealing the object between. Thereafter, all vacuum suction is turned off 
and the upper vacuum frame is lifted away from the lower platen revealing 
the product in a completely airtight plastic package.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring to the drawings wherein like reference characters designate like 
or corresponding parts throughout the several views, and referring 
particularly to FIG. 1, it is seen that the invention includes a hollow 
overhead rectangular frame 12 attached by conduit 16 to vacuum chamber 30. 
A corresponding lower rectangular frame 28 is provided immediately below 
overhead frame 12. A heatable platen 10 is provided on said lower frame 
28, one embodiment of which includes a plurality of longitudinal parallel 
transverse channels 11 in the shape of alternating ridges 13 and valleys 
which form the top surface of the lower platen (see also FIG. 3 and FIG. 
5). The other platen embodiment is shown in FIGS. 4 and 6. An electronic 
control mechanism 44 is provided which operates apparatus by controlling 
the application of the vacuum, controlling the heating elements, opening 
and closing the frame, etc. 
A pair of troughs 23, 24 are provided on two opposite sides of lower frame 
28. Channels 11 are defined by the valleys between the ridges 13, and 
begin at the inside edge of side trough 24 and end at the inside edge of 
opposite side trough 23. Each of said channels 11 includes a plurality of 
openings 26 in the valleys thereof along the entire length of each channel 
(see FIGS. 2B and 2C). These openings 26 allow vacuum conduit 17 to draw 
air into the collection chamber 29 directly below lower platen 10 as shown 
in FIG. 2A. 
Side troughs 23, 24 are perpendicular to the transverse channels 11 and 
form a border to platen 10 through which air is drawn into the side vacuum 
collection chamber 21 through a separate conduit 22. Vacuum 30 provides 
vacuum suction to upper frame 12 through conduit 23, to platen 10 through 
conduit 17, and to side troughs 23 and 24 through conduit 22. 
An alternative four-sided embodiment of the lower platen 10 is described in 
FIGS. 4, 4A, and 6. This embodiment includes four troughs, one along each 
side, 23, 23a, 24 and 24a. The surface of the platen itself is in the 
shape of four triangles, the sides of which are defined by the diagonals 
between the opposing corners of the platen. All of the channels 11 of this 
embodiment include one right angle at the diagonal. The triangular shape 
of the four sections of this embodiment provide for a more efficient and 
complete removal of air through all four troughs. 
Referring now specifically to FIGS. 1, 7A and 7B, the operation of 
packaging an object 34 and the employment of the platens and troughs will 
be described. A first sheet of plastic 32 is loaded into the upper vacuum 
frame 12. By opening air gate 36 to conduit 16, air will be evacuated 
around the perimeter of sheet 32 through upper frame 12. Heating element 
34 contained in upper frame 12 is then activated. At the same time, a 
second sheet of plastic 20 is placed on the lower platen 10, and the lower 
heating element (not shown) is activated. The two heating elements cause 
the first and second sheets of plastic, 32 and 20, to become deformable. 
Sheet 32 sags or bows in the middle as a result (see FIG. 7A). By opening 
air gate 18 to conduit 17, air will be evacuated through collection 
chamber 29 which in turn will pull and shape the second plastic sheet 20 
through openings 26 to fit precisely against the contours of the ridges 13 
and channels 11 of the lower platen 10. 
The object to be sealed 33 is placed on top of deformed lower plastic sheet 
20. The upper vacuum frame 12 is then lowered into position over lower 
frame 28 causing the first sheet 32 to come into contact with object 33. 
As frame 12 continues downward, air gate 31 to conduit 22 is opened 
causing air to be evacuated through side troughs 23 and 24 by means of 
side venturi 27 and 25 (see FIGS. 7A and 7B). When the upper frame has 
come all the way down (see FIG. 7B), air gate 18 to conduit 17 is shunted 
at increasing timed intervals causing the upper plastic sheet 19 to be 
pulled and shaped to fit precisely the contours of the object 33 and 
channels 11. Finally, air gate 36 to conduit 16 is closed, dislodging 
plastic sheet 32 from the upper frame 12, allowing the edges of the two 
plastic sheets 20 and 32 to adhere to each other, creating an airtight 
hermetically sealed package. 
It is to be understood that variations and modifications of the present 
invention may be made without departing from the scope thereof. It is also 
to be understood that the present invention is not to be limited by the 
specific embodiments disclosed herein, but only in accordance with the 
appended claims when read in light of the foregoing specification.