Vacuum packaging machine

In a vacuum packaging machine having a forming station and an evacuation and sealing station, wherein each station has a chamber made of an upper and a lower part, and each part comprises a base portion (top cover or floor, as the case may be) and four upstanding walls, one or both of said chamber parts is made from material having an appropriate cross-sectional shape, preferably U-shaped, forming the base portion and opposite side walls, the front and rear walls being secured thereto in the form of covers. The cross-sectional shape may be double U-shaped, providing accommodation for connections for chamber supply requirements (vacuum, air, power). Also the cooling plate for the lower part is secured on the under-side of the floor of said part and mounts it on the means for imparting chamber opening and closing movement to the lower part, while the cooling plate for the upper part is inside the chamber, on the under-side of the top cover.

BRIEF SUMMARY 
This invention is concerned with improvements in or relating to vacuum 
packaging machines. 
In a vacuum packaging machine, as e.g. described in U.S. Pat. No. 
3,673,760, depressions for receiving the goods to be packaged are usually 
formed in the one foil, which serves as the lower foil at a forming 
station. Thereafter, with the upper foil laid over the depressions with 
the goods therein, evacuation and sealing together of the foils then takes 
place. Both the process of forming the depressions in the lower foil on 
the one hand and also the evacuation and sealing of the packages on the 
other are effected each in a chamber comprising two parts, viz. an upper 
and a lower part, said parts being movable relative to one another in 
order to effect closure and opening of the chambers. The chambers 
accommodate the requisite devices, e.g. the compartments for forming the 
desired depressions or the sealing devices, as the case may be. 
Furthermore, the necessary connections for the supply requirements of the 
chambers, viz. a vacuum line and a line for air under pressure, an energy 
supply and a cooling system, are provided in the chambers. 
In general the chambers are formed as aluminum castings, the castings each 
being appropriate to the desired size of the packages. Significant 
variations in the size can, however, arise. One or several lines of 
packages can be prepared one beside the other and the length also of the 
packages differs. According to the length of each package, several rows of 
packages are simultaneously prepared, that is to say e.g. formed and then 
evacuated and sealed after insertion of the goods. 
The aluminum castings from which the lower and upper chamber parts are 
formed must be exactly machined, even on those surfaces which do not 
co-operate with other surfaces. The production of the chambers is thus 
costly. Also, the problem frequently arises with a machine which is 
already in operation that, because the packages to be produced undergo 
alterations with regard to their dimensions, the chambers have to be 
exchanged after installation. The production of new chambers which are 
compatible with the new size is then seen to be very time-consuming. 
Furthermore, because of the multiplicity of sizes, it is not generally 
viable to provide tooling in order to reduce the production time, and in 
any event tooling is prohibited because of the cost involved. 
The present invention has for its object to provide a vacuum packaging 
machine having chambers as aforesaid, but in which it is possible to 
reduce significantly both the cost of production and also the production 
time without detriment thereby to the quality of the chambers in question. 
The invention thus provides a vacuum packaging machine comprising chambers 
for forming the packaging foil and for evacuating and sealing the 
packages, each chamber comprising an upper and a lower part, which parts 
are moveable relative to one another and, in an operative position in 
which they are pressed together, clamp marginal portions of the foils 
therebetween, and each chamber part comprising a base portion 
(constituting a top cover of the upper chamber part and a floor of the 
lower chamber part) and four walls arranged in a rectangle and upstanding 
from said base portion, wherein at least one of said chamber parts is made 
from a length of material having an appropriate cross-section profile, to 
which the front and rear walls are secured in the form of covers for the 
ends thereof. 
Various possibilities present themselves for the construction of the 
machine in accordance with the invention. For example, each chamber part 
may consist of a floor or top cover, as the case may be, and four separate 
walls, such chamber thus being an assembly of five component parts. 
Preferably, however, the profile of said material is such that it provides 
not only the floor or top cover, as the case may be, but also opposite 
side walls integral therewith, that is to say the floor or top cover, as 
the case may be, and the two side walls together form a U-shaped extrusion 
shape. In this way such chamber part consists essentially of only three 
component parts, viz. the U-shaped center portion and the two walls 
attached in the manner of covers. 
Furthermore, conveniently the extrusion shape of the upper chamber part may 
have a double U-shape thus providing at the outside of one of the side 
walls a space for accomodating connections for the supply requirements to 
the chamber, which space is U-shaped and open underneath. The connections 
are preferably assembled in a block which can be fitted out away from the 
chamber or chamber part and then be inserted in the space therefor after 
completion. Alternatively in another construction avoiding said U-shaped 
space open underneath, the connections may be assembled in a block which 
is secured to the outside of one of the side walls. 
As is conventional in vacuum packaging machines, the chamber for evacuating 
and sealing is preferably provided with a cooling system, such system 
being required because of the heat produced at that station. In the past, 
various constructions have been available for use. For example high 
intensity cooling has been achieved in the previously used aluminum 
casting by inserting a cooling coil therein, thereby affording a cooling 
effect in the floor or top cover, as the case may be. Alternatively, it 
has been customary to screw a plate in which a cooling channel has been 
machined on to the floor or top cover, as the case may be, sufficiently to 
obtain adequate surface contact therebetween. 
The present invention also provides a novel solution to this problem of 
cooling. Thus in the machine in accordance with the invention the lower 
chamber part is preferably provided with a cooling plate having channels 
for the coolant which are closed on all sides, said plate being e.g. 
arranged beneath the lower chamber part, which part is supported by said 
cooling plate on the means for moving said lower part heightwise. 
Generally, therefore, even for chambers of different dimensions the same 
cooling plate can always be used. In this way, similarly, the production 
of the machine and tooling therefor are simplified. 
If desired, such a cooling plate may also be used with the upper chamber 
part, said plate being inserted into said chamber part on the underside of 
the top cover. This arrangement has the added advantage that in special 
cases, where a cooling effect in the upper part can be dispensed with, it 
is possible readily to accommodate these requirements.

DETAILED DESCRIPTION 
Referring to FIGS. 1 and 2, the first illustrative embodiment has a chamber 
the upper part generally designated 11 (FIG. 1) of which is formed as a 
double U-shape. The side walls 9, 10 are formed integral with the top 
cover 6, and on the outside of said walls are provided the spaces 12, 13, 
which are U-shaped and open underneath. The spaces 12, 13 are bounded at 
their outside by the walls 18, 19. These various component parts 6, 9, 10, 
18, 19 of the upper part of the chamber thus have a cross-sectional 
profile and can be provided from material having such a profile. 
The invention thus departs from the previous method of production from 
aluminum castings which are subsequently machined, and turns to production 
from material having an appropriate cross-sectional profile, which is of 
course produced in large quantities. This material is generally prepared 
by an extrusion process and it has been found that by this production 
method on the one hand manufacturing tolerances can be adequately achieved 
and on the other hand the surfaces are sufficiently smooth so that 
subsequent machining on the outer surfaces of the material are by and 
large unnecessary. 
Thus, when a chamber of given dimensions is to be made the corresponding 
length is cut from the material for the particular chamber part and it is 
then necessary only to machine the under-side 20 of the walls 9, 10 and 
the end surfaces, i.e. the cut faces, so that the attached covers which 
constitute the forward and rearward walls 1, 2, will form an adequate seal 
therewith. 
Since the material having the appropriate cross-sectional profile can be 
used in practically every case, no problems arise in jigging the material 
and clearly in this way not only are production costs reduced because the 
number of surfaces to be machined is low, but especially the production 
time is greatly reduced also. 
Furthermore, since it is possible for the outer dimensions of the chamber 
for the forming station and of that for the evacuation and sealing station 
to be compatible with each other, the invention requires only material of 
said profile for the upper part or the lower part, as the case may be. 
As already mentioned, the front and rear sides of the component parts 6, 9, 
10, 18, 19 are covered by the walls 1, 2 in the form of covers. These are 
secured by means of screws 21, with suitable sealing means interposed. 
Of the spaces 12, 13 which are open underneath in the form of an inverted 
U, the space 12 receives the block 14. In the block 14 the necessary 
connections are accommodated, namely for the cold water inlet and outlet, 
the supply of air under pressure and the vacuum. Corresponding bores in 
the wall 9, leading to the inside of the chamber, then connect to the 
block 14. 
Inside the chamber the cooling plate 17 is secured to the under-side of the 
top cover 6 and the guide bolts 22 serve to locate the pressure plate 24, 
which is moveable under the action of the pressure cushion 25, which can 
be pressurised by air under pressure. The springs 23 return the pressure 
plate upwardly when the pressure cushion is evacuated. The pressure plate 
24 carries the surface heater or sealing frame 26 which co-operates with 
the sealing rubber seal 27 on the lower part generally designated 16 of 
the chamber. An insulating layer 28 is also provided between the pressure 
cushion 25 and the pressure plate 24. 
The lower part 16 of the chamber comprises the floor 5 and the walls 7, 8 
unitarily connected therewith. At the forward and rearward ends are 
provided the walls 3,4 which, similarly as with the upper part, are 
secured by screws 21 to the U-shape. 
Beneath the floor 5 is provided the cooling plate 15, by means of which the 
lower part of the chamber is supported on the means (not shown) for moving 
said lower part heightwise. 
As is known per se in a cycle of operation of the machine the lower part 16 
of the chamber is moved up and down in the direction of the arrow 29, so 
that the lower foil 30 with the cup-like depressions 31 can be introduced 
into the chamber. After evacuation, the upper foil 32 is welded to the 
lower foil and the chamber is then opened. The drive means for moving the 
upper part of the chamber engage on the fixings 33. 
Referring now to FIGS. 3 and 4, the components built into the space 36 of 
the second illustrative embodiment are not shown in detail, since they are 
conventional and known per se. The upper part 11' of the chamber in this 
embodiment is constructed from a top cover 6', which has a plate-like 
shape and on which the walls 1', 2', 9', 10' are mounted. The connection 
between the top cover and walls is thus made by screws 21'. On the outside 
of the side wall 9' is screwed the block 14' into which the connections 34 
are inserted for the various actuating means of the chamber. Bores 35 are 
provided in the wall 9' and enable the inside chamber 36 to be connected 
up. O-rings 38 set into the block 14' provide a seal for the 
interconnection of the connections 34 with the bores 35. The block 14' is 
secured by screws schematically shown at 39. 
A further block 37 is secured on the other wall 10' in the same manner as 
the block 14' on the wall 9'. This block 37 has only the fixing means 33', 
which are also provided on the block 14'. The fixing means serve to 
connect the chamber with the other parts of the machine. 
The foils between the two chamber parts 11', 16' are designated 30' and 
32'.