U.S. patent number 3,597,897 [Application Number 04/868,065] was granted by the patent office on 1971-08-10 for method of and apparatus for vacuum sealing packs.
This patent grant is currently assigned to W. R. Grace & Co.. Invention is credited to Alain Gerard.
United States Patent |
3,597,897 |
Gerard |
August 10, 1971 |
METHOD OF AND APPARATUS FOR VACUUM SEALING PACKS
Abstract
This invention relates to a method of and apparatus for vacuum
sealing packs. Primarily, there is provided a cover movable in a
first direction from a position adjacent a first sealing station to
a position adjacent a second sealing station, and then in a second
direction substantially perpendicular to the first direction to
form a closed vacuum sealing chamber at the second station whereat
a vacuum sealing operation is conducted. Preferably an
electromagnetic arrangement is provided so that the cover can be
precisely positioned adjacent the sealing station at the end of
movement in the first direction.
Inventors: |
Gerard; Alain (Saint-Coud,
FR) |
Assignee: |
W. R. Grace & Co. (New
York, NY)
|
Family
ID: |
25351007 |
Appl.
No.: |
04/868,065 |
Filed: |
October 21, 1969 |
Current U.S.
Class: |
53/84; 53/85;
53/512; 53/86 |
Current CPC
Class: |
B65B
31/024 (20130101); B29C 66/1122 (20130101); B29L
2031/7128 (20130101); B29C 66/00145 (20130101); B29C
65/224 (20130101); B29C 66/8324 (20130101); B29C
66/849 (20130101); B29C 66/43121 (20130101); B29C
65/222 (20130101); B29C 65/7451 (20130101); B29C
66/82421 (20130101) |
Current International
Class: |
B65B
31/02 (20060101); B65b 031/02 () |
Field of
Search: |
;53/86,84,85,79,93,112B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGehee; Travis S.
Claims
I claim:
1. Apparatus for vacuum-sealing packs, such apparatus
comprising:
a. a plurality of sealing stations;
b. a plurality of vacuum-applying means, one of said
vacuum-applying means being provided at each sealing station;
c. cover means, said cover means being movable between the sealing
stations to provide a closed vacuum sealing chamber sequentially at
each station;
d. first means for positioning the cover means in a first direction
above one sealing station; and
e. second means for moving the cover means in a second direction
substantially perpendicular to the said first direction to form a
closed vacuum-sealing chamber at the respective sealing
stations.
2. Apparatus according to claim 1 in which the said first means
includes a guide arrangement for guiding the cover in the said
first direction.
3. Apparatus according to claim 1 in which the said second means
includes a jack arrangement for moving the cover means in the said
second direction.
4. Apparatus according to claim 3 in which the said second means
includes a counterbalance device, said counterbalance device being
adapted to cooperate with the jack arrangement during movement of
the cover means in the said second direction.
5. Apparatus according to claim 1 wherein said first means includes
a plurality devices for temporary linking and coupling, one of said
temporary linking and coupling devices being associated with each
sealing station for positioning the cover means in a precisely
defined position above each sealing station at the end of its
movement in the said first direction.
6. Apparatus according to claim 5 in which each temporary linking
and coupling device includes a fixed linking and coupling member,
which in a linked and coupled position of the cover member apply
electrical power to electrical units carried by the cover
member.
7. Apparatus according to claim 5 in which each temporary linking
and coupling device comprises a stationary member, a first
transformer half-circuit including a primary winding, said first
transformer half-circuit being mounted on the fixed member and a
second transformer half-circuit including a secondary winding, said
second transformer half-circuit being mounted on the cover means,
the cover means and the fixed member being so arranged that the
first and second half-circuits are held engaged and linked by
induced magnetic flux in said precisely defined position.
8. Apparatus according to claim 1 including sealing members at each
sealing station and in which the cover means has a positioning
device for bringing the portion of a pack to be sealed, positioned
at a sealing station, into engagement with the sealing members of
the sealing station to allow sealing to take place.
9. Apparatus according to claim 8, in which the positioning device
includes a member for engaging the pack, an expandable envelope for
moving the member toward and away from the sealing members of the
sealing station in dependence of the relationship of the pressure
in the envelope and the pressure in the sealing station, and a
three-way valve, said three-way valve connecting the interior of
the envelope with either the atmosphere or the interior of the
cover during movement in the first direction.
Description
THIS INVENTION relates to a method of, and apparatus for
vacuum-sealing packs.
Machines are known for vacuum-sealing packs. These machines
generally comprise on a fixed plate two stations which are each
provided with a supporting element, a port connected to a vacuum
pump, and a sealing device the mobile portion of which cooperates
with a pressing jaw. These machines also comprise a single mobile
cover intended to cover one station and now the other, to isolate
it from the exterior whilst a relative vacuum is established
therein and the sealing of the pack is carried out.
The aforesaid cover is connected to the fixed plate in such a
manner as to be manually displaceable from one station to the other
without touching the packed products arranged on the said stations.
For this purpose, the connection of the cover with the plate is
effected at each side by means of two pivoting links which are
parallel to one another and of equal length. By means of this
device, a circular translational movement of the cover is obtained
which permits the cover, in moving parallel to itself, to be raised
so as not to encounter the packed goods.
A first disadvantage of this type of machine resides in the fact
that the lateral walls of the cover have to be inclined
considerably, especially if the packed goods are relatively high,
if one wishes to avoid the covers striking the said goods during
the circular translational movement. As a result, the internal
volume of the cover is larger than would be sufficient for it
simply to cover the product; consequently a considerable amount of
energy has to be used in order to provide a vacuum and more
especially the vacuum-establishing operation takes longer.
Furthermore, the pivoting movement of the cover-carrying link is
difficult to start manually since it is conducive to lifting the
said cover. The operator is needlessly fatigued as a result. Also
it is not possible to reduce the fatigue since in order to reduce
the inclination of the lateral walls of the cover and the general
bulk of the machine, it is necessary to choose links of limited
length.
The known machines are arranged so that in their operating cycle,
the operations of onloading and off-loading the products are
carried out manually or automatically. But, in the latter case,
automatic conveyors are used which comprise independent parts which
constitute the supporting elements situated at the two machine
stations. These automatic devices are expensive and they consume
energy, and their control in relation to time with that of the
other operations requires excessive complication of the machine and
a loss of time at high working rates.
Furthermore, the control of the sealing devices used in these known
machines is triggered by a time switch, that is to say with a
certain amount of delay relatively to the instant when the vacuum
standard is reached in the cover. Finally, these known machines
comprise hanging electric cables for the supply of the elements
carried by the cover, these cables of course constituting a
hindrance to the operator's work and a source of faults.
According to one aspect of the present invention there is provided
apparatus for vacuum-sealing packs, such apparatus comprising a
plurality of sealing stations each being provided with
vacuum-applying means and a cover movable between the sealing
stations to provide a closed vacuum-sealing chamber sequentially at
each station, the cover being mounted for movement in a first
direction between a position adjacent one sealing station and a
position adjacent a second sealing station and in a second
direction substantially perpendicular to the said first direction
to form the closed vacuum chamber at the respective sealing
stations.
Preferably, the apparatus includes a temporary linking and coupling
device associated with each sealing station for positioning the
cover in a precisely defined position adjacent each sealing station
at the end of its movement in the said first direction.
Each temporary linking and coupling device may include a relatively
fixed linking and coupling member, which in the linked and coupled
position of the cover supplies electrical power to electrical units
carried by the cover member.
Further, each temporary linking and coupling device may comprise a
first transformer half circuit including a primary winding mounted
on the fixed member and a second transformer half circuit including
a secondary winding mounted on the cover member, the cover and the
fixed member being so arranged that the first and second half
circuits engage and are held in linked engagement by induced
magnetic flux in the precisely defined position.
According to a further aspect of the present invention there is
provided a method of vacuum-sealing packs comprising moving a cover
member from a position adjacent a first sealing station in a first
direction to a position adjacent a second sealing station and then
moving the cover member in a second direction substantially
perpendicular to the first direction to form a closed
vacuum-sealing chamber at the second sealing station and vacuum
sealing a pack positioned at the second sealing station .
An illustrative embodiment of the invention will now be described
with reference to the accompanying drawings, in which:
FIG. 1 is a simplified perspective view of one form of
apparatus;
FIG. 2 shows a vertical sectional view taken on a larger scale of
the line II-II of FIG. 1 and shows more particularly the device for
actuating in the ascending and descending sense the mobile assembly
in which the cover is integrated.
FIGS. 3 and 4 are simplified sectional view taken on a larger scale
on the lines III-III and IV-IV respectively of FIG. 1 illustrating
the pressing jaw accommodated in the cover and the device for
causing inclination of each supporting element, and
FIG. 5 is a pneumatic and electrical diagram showing the control of
the various parts of the apparatus.
Referring now to FIG. 1 there is shown apparatus comprising a rigid
frame 1 having a plate 2 mounted thereon. On the top plate 2 there
are provided two working stations 3 and 4 each of which is adapted
to be covered selectively by a mobile cover 5 to form a closed
chamber in which a motor-pump assembly 6 can establish a sufficient
vacuum for vacuum-sealing.
Provided at each of the stations 3 and 4 (FIGS. 1 and 3) is a fixed
insulating bar 7 on which are mounted a heating strip 8 for the
sealing of the packs and a cutting wire 9 for cutting-off excess
packaging material, this strip and wire are connected to an
electrical current source.
At each of the stations 3 and 4 there is also provided a supporting
element generally indicated by the reference numeral 10 and
constituted by an inclinable roller table. In the example
illustrated in FIGS. 1 and 4, this table comprises two flat bars 11
connected to one another by parallel rods 12 on which wheels or
sleeves 13 are freely mounted. This table is simply positioned on
the plate 2 and is articulated at one side of the apparatus about
fixed shafts 14 extending through the ends of the bars 11, and
through brackets 15 fixed to the plate 2. Consequently, when the
table 10 is lifted at its unsecured end it will pivot about the
shafts 14 and is inclined so that it presents a descending slope
from the front towards the rear of the apparatus. Consequently,
packed goods that have been vacuum sealed in the apparatus can be
transported to a discharge table 16 by merely pivoting the table 10
upwardly. The table 16 is mounted rearwardly of the plate 2 by
butterfly nuts 17, which are adjustable so that the inclination of
the table 16 may be regulated. In practice a discharge conveyor
cooperates with the table 16 thus enabling sealed packs to be
transported away from the apparatus.
The cover 5 is guided along a horizontal slideway which comprises
(FIG. 1 and 2), two parallel cylindrical bars 18, which are rigidly
connected at their free ends to angled cross members 19 and 20. The
bars 18 are located above the cover 5 and extend through apertures
in projecting portions 21 of the cover 5. Conveniently these
apertures are provided with bushings, ball bearing sleeves or other
guide elements, thus enabling the cover to be easily displaced
manually in a horizontal direction by means of a handle 22.
The assembly constituted by the horizontal slideway and the cover 5
is movable vertically relative to the frame 1. For this purpose,
the cross member 19 is secured to two columns 23 extending through
a boss 24 of the plate 2, the boss 24 is provided with guide
elements such as bushings, or ball bearing sleeves. In a similar
manner, the crossmember 20 is secured with column 25 extending
through a boss 26 in a similar manner to the columns 23. All these
columns project within the frame 1 and are connected to one another
rigidly at a sufficiently low level, in order to constitute with
the horizontal slideway and the cover a vertically mobile assembly.
For example, the columns 25 are connected by a lower crossmember 27
and the columns 23 by another lower crossmember, these two
crossmembers 27 being themselves connected by a connecting bar 28
extending parallel to the horizontal slideway 18.
The mobile assembly thus constituted is adapted to be displaced
vertically by an actuating device generally indicated by the
numeral 29 and which may be of any desired type. However, in the
example illustrated in FIG. 2, the device 29 comprises a jack 30
interposed between the fixed portion of the frame 1 and the central
portion of the bar 28 of the mobile assembly. However, since the
apparatus comprises a motor-pump arrangement 6 the jack 30 is
conveniently of a vacuum type. Furthermore, the jack is preferably
the single-acting type and controls the upward movement of the
mobile assembly, while the downward movement can be effected
automatically by gravitational force. The cylinder 31 of the jack
30 can then be fixed on the bar 28 and the piston rod 32
articulated below the plate 2. In this case, the upper connecting
pipe 33 of the jack cylinder is connected permanently to the
atmosphere whereas its lower connecting pipe 34 is adapted to be
connected by means described hereinafter either to the vacuum
generator 6 or to the atmosphere.
The actuating device 29 can be constituted solely by the jack 30
which, under these conditions, is of a relatively large diameter in
order to develop a force at least equal to the total weight of the
mobile assembly. However a smaller jack may be employed if a
counterpoise arrangement is provided for the mobile assembly. Such
a counterpoise device, may, for instance, comprise a spring 35
interposed between a fixed portion of the frame 1 and the mobile
assembly. However, since the preload of the spring will vary in
accordance with its elongation, the load on the jack 30 will not be
constant. In order to remedy this, a correcting cam 36 is
provided.
In the example illustrated in FIG. 2, the cam 36 and a sprocket 37
are mounted on a shaft 38 mounted freely in a bearing 39 and fitted
below the plate 2. A chain 40 is attached by its lower end to a
central member 41 of the bar 28. This chain 40 is in part wound
over the sprocket 37 and is fixed thereto by its upper end link.
Another chain 42 applied to the correcting profile of the cam 36 is
fixed at one of its ends to the cam and attached at its other end
to the spring 35. The spring 35 is a tension spring and is attached
at its free end to a support 43 mounted on the frame 1. The spring
35 tends to lift the mobile assembly by applying thereto, through
the agency of the chain 40, a force which is directed upwards and
is substantially constant, by means of the action of the profile of
the cam 36. In practice this force is less than the weight of the
assembly, which has the result of relieving the action of the jack
30.
It will be seen from the foregoing that by subjecting the jack 30
to negative pressure the upward movement of the mobile assembly
and, more particularly, the cover 5, is achieved. This upward
movement is strictly vertical since the coupling means described
hereinafter are provided between the cover and the crossmember 19
or the crossmember 20. Consequently, the vacuum-packed products
located on the table 10 at the station 4 are not damaged by the
cover during its upward movement. When cover 5 is in the upper
position after completing a sealing operation at the station 4, all
the operator has to do is to displace the cover manually along the
guide bars 18 to bring it above the station 3 and couple it to the
crossmember 19. By connecting the jack 30 to the atmosphere, the
mobile assembly will descend by gravitational force over a pack to
be sealed without damaging the pack.
The two bars 7 for sealing and cutting at the stations 3 and 4
cooperate with a single jaw 44 (FIG. 3) accommodated in the cover
5. This jaw is vertically movable in the cover by means of a jack
arrangement.
In the example illustrated in FIG. 3, the actuation and, if
appropriate, the guiding of the jaw 44 are effected by means of a
jack in the form of a tubular envelope 45 made of elastic material
which is carried by the cover and connected to the jaw. This
envelope is adapted to be connected either to the chamber within
the cover or to the atmosphere by an element described hereinafter.
If the pressures prevailing in the envelope 45 and in the cover 5
are balanced, either by ambient pressure or the lower pressure
produced by the vacuum pump, the envelope is in a position of rest
(FIG. 3) wherein the jaw 44 is spaced from the electrodes 8 and 9,
even if the cover 5 is applied against plate 2. On the other hand,
if the pressure prevailing in the envelope 45 is the ambient
atmospheric pressure and the cover is subjected to vacuum, the
envelope is inflated and applies the jaw 44 with sufficient force
against the electrodes 8 and 9, pressing the two walls of a pack
arranged between them. Of course, it does not matter much whether
the pack in question is a bag containing a bulky product such as an
entire ham, or whether it is a small packet containing a product
which is not very bulky, such as slices of ham.
In order to control the jack 30 and hence the upward or downward
movement of the cover 5, the control of the element which regulates
the connection to the motor-pump arrangement 6 of the station to be
subjected to vacuum (which is selected by the cover 5) and the
control of the element which controls the connection of the
envelope 45 carried by the cover, either to the latter or to the
atmosphere, various means may be used and, for example, an
electrical or pneumatic program control device which trips the
aforesaid controls in timed manner.
A preferred form of control device is shown very diagrammatically
in FIG. 5.
Referring now to FIG. 5 there is shown a control device comprising
two three-way electromagnetic valves 46 and 47, connected
respectively by a conduit 48 to the vacuum pump of the arrangement
6, to the atmosphere by connecting pipe 49 or 50 and to a port 51
or 52 provided in the plate 2 at the location of the station 3 or 4
respectively. In the condition of rest, that is to say when control
windings 53 and 54 of the electromagnetic valves 46 and 47 are not
energized, these electromagnetic valves connect the ports 51 and 52
to the connecting pipes 49 and 50 connected with the atmosphere. On
the other hand, when the winding 53 or 54 is energized, the
corresponding electromagnetic valve 46 or 47 connects the port 51
or 52 to the vacuum pump of the arrangement 6. A microcontact 55 is
mounted on the crossmember 19 opposite a pushbutton 56 carried by
the cover 5. This microcontact, by means of a branch line 57 of the
main electrical line 58 supplying the motor of the arrangement 6,
controls the energization of the winding of a relay 59 whose
contact itself controls the connection of the control winding 53 of
the electromagnetic valve 56 to a branch 60 of the line 58. In a
similar manner a microcontact 61 is mounted on the crossmember 20
opposite a control push member 62 carried by the cover 5. This
microcontact is connected to a branch 63 of the line 58 provided
for the energization of the winding of a relay 64 whose contact is
connected to another branch 65 of the line, supplying the control
winding 54 of the electromagnetic valve 47.
The control device shown in FIG. 5 further includes another
three-way electromagnetic valve 66 which is connected by a conduit
67 to the vacuum pump of the arrangement 6, to the atmosphere by a
connecting pipe 68 and by a conduit 69 to the lower connecting pipe
34 of the jack 30 for actuating the mobile assembly 5-19-20. As in
the previous case, the control winding 70 of the electromagnetic
valve 66 is connected in series to a branch 71 of the line 58 and
under the control of a relay 72. The energization winding of this
relay is itself connected in series to another branch 73 of the
line and under the control of either a microcontact 74 carried by
the crossmember 20 or a microcontact 75 carried by the crossmember
19. For this purpose, these microcontacts 74 and 75, which are also
controlled by push members 76 and 77 of the cover 5, are connected
by means of conductors 78 in parallel to one another and in series
to the branch 73.
The electromagnetic valves 46, 47 and 66 are fixed and accommodated
in the frame 1. The device shown in FIG. 5 comprises another
three-way electromagnetic valve 79 which is mounted in the cover 5.
The electromagnetic valve 79 opens through a connecting pipe 80
into the cover, is connected through a connecting pipe 81 to the
inflatable envelope 45 acting on the pressing jaw 44, and is
connected to the atmosphere by a conduit 82. To control the
electromagnetic valve 79 use is preferably, but not necessarily,
made of two devices for temporarily connecting the mobile assembly
to a coupling element at both of the stations 3 and 4 for
positioning the cover in position and for supplying electrical
energy to elements arranged in the cover. In practice these two
devices permit not only the controlling of the electromagnetic
valve 79 (and, where appropriate, supplying other electrical
components carried by the cover 5) but also of temporarily coupling
the cover either to the crossmember 19 or to the crossmember 20
with a view to defining precisely the position of the cover above
either the station 3 or the station 4.
A first device of the aforesaid type comprises a magnetic
half-circuit 83 fixed directly or by means of springs to the
crossmember 19 and another magnetic half-circuit 84 fitted opposite
the aforesaid circuit in the cover 5. The primary winding 85
mounted on the magnetic half-circuit 83 is connected to a branch 86
of the line 58 and under the electrical control of an element
sensitive to the pressure prevailing in the cover 5. In the example
illustrated, this element is a contact manometer 87 whose pneumatic
chamber is connected by a conduit 88 to a pressure pickup 89
situated at the station 3 of the apparatus. The contact of this
manometer is connected in series to the branch 86 and it opens when
the pressure prevailing in the cover 5 covering the station 3
corresponds to the vacuum rate selected for sealing. The secondary
winding 90 mounted on the magnetic half-circuit 84 of the cover is
connected by conductors 91 to the terminals of the energization
winding 92 of the electromagnetic valve 79.
In a similar manner, the second device comprises a magnetic
half-circuit 93 mounted on the cover 5 and whose secondary winding
94 is connected by conductors 95 to the terminals of the
energization winding 92 of the electromagnetic valve 79. This
device also comprises another magnetic half-circuit 96 mounted on
the crossmember 20 and whose primary winding 97 is connected to a
branch 98 of the line 58 and under the control of a contact
manometer 99 whose pneumatic chamber is connected by a conduit 100
to a pressure pickup 101 situated at the station 4 of the
machine.
In use, the above described apparatus, operates as follows. When
the mobile assembly is situated in its upper position, the operator
brings the cover 5 against the crossmember 20.
In this position, it is noted first of all that the two magnetic
half-circuits 93 and 96 are in contact with each other to form the
completed circuit. As the manometer 99 detects the atmospheric
pressure at the pickup 101, its contact is closed and the primary
winding 97 of the transformer is supplied by the branch 98. The
magnetic field produced by this primary winding closes across the
complete magnetic circuit and the forces which appear tend to hold
the two parts 93 and 96 secured to one another. Furthermore, the
magnetic field gives rise by induction in the secondary winding 94
to an electrical current which supplies the winding 92 controlling
the electromagnetic valve 79. As a result, the mobile part of the
electromagnetic valve connects the envelope 45 of the jaw 44 to the
connecting pipe 80 projecting into the cover 5 and, since the
pressures prevailing in the latter and in the envelope tend to
balance, the jaw 44 will remain spaced from the electrodes 8 and 9
even when the cover 5 is applied to the plate 2.
In the aforesaid position and at the instant when the cover 5 comes
to abut on the crossmember 20, the two microcontacts 61 and 74 are
closed by the push members 62 and 76.
The microcontact 61 detects which station the cover 5 has arrived
at, and closes the supply circuit 63 of the relay 64 which
immediately, or with a slight delay, connects to its own supply
circuit 65 the control winding 54 of the electromagnetic valve 47.
The mobile part of the latter then connects the conduit 48 to the
port 52, that is to say it connects the vacuum pump of the pump
arrangement 6 to the station 4.
The microcontact 74, which also permits detection of the position
of the cover 5 closes the supply circuit 73 of the relay 72 which
immediately connects the control winding 70 of the electromagnetic
valve 66 to its own supply circuit 71. Owing to this valve, the
conduit 69 is connected to the connecting pipe 68 so that the jack
30 is connected to the atmosphere by its lower connecting pipe 34.
Under these conditions, the mobile assembly and more particularly
the cover 5 descend by gravitational force until the latter is in
sealing-tight contact with the plate 2.
Vacuum is then established progressively in the cover 5 and in the
pack or packs containing the product or products to be sealed. The
vacuum is also established in the envelope 45. When the pressure in
the cover 5 reaches the value selected for sealing, the contact of
the manometer 99 opens and the result is that the primary winding
97 of the transformer is no longer supplied. The secondary winding
94 can then no longer supply the energization winding 92 of the
electromagnetic valve 79. The latter returns to its original
position and consequently it connects the envelope 45 to the
atmosphere. The envelope 45 is then inflated and applies the jaw 44
to the electrodes 8 and 9 through the walls of the pack or packs.
The pressure exerted is substantially equal to the difference
between the atmospheric pressure and a reduced pressure prevailing
in the cover. Since the electrodes 8 and 9 are supplied, the
welding of the walls of the pack is effected together with the
cutting of the excess material from the packs.
Then the supply to the control winding 70 of the electromagnetic
valve 66 is interrupted. This operation can be carried out by the
relay 72 if the latter is of the type having a delayed-action
cutoff. It may also be effected by a manometer 99 if the latter
comprises a second contact with delayed action connected in series
with the branch 71. In any case, as soon as the winding 70 is no
longer supplied, the electromagnetic valve 66 connects the conduits
67 and 69 to one another, that is to say the vacuum pump of the set
6 to the actuating chamber of the jack 30.
At the same time, the supply to the control winding 54 of the
electromagnetic valve 47 is itself interrupted. This operation can
be carried out in the same manner as previously, that is to say by
using a relay 64 of the type with delayed-action cutoff or a third
delayed-action contact of the manometer 99. In any case, as soon as
the winding 54 is no longer supplied, the electromagnetic valve 47
connects the port 52 to the connecting pipe 50 and thus connects to
the atmosphere the internal chamber in the cover 5 and the envelope
45.
Thus with the pressures being balanced, the jaw 44 moves upwards
and frees the pack. Furthermore, as the cover 5 is connected to the
atmosphere while the jack 30 is under vacuum, the mobile assembly
moves upwards in its entirety. The cover 5 is then positioned above
the sealed product or products and can therefore be displaced by an
operator as far as the crossmember 19, a position in which it is
situated vertically above the station 3.
The same cycle as that described hereinbefore takes place but this
time using the transformer 83-84, the microcontacts 55 and 75, the
electromagnetic valve 46 and the contact manometer 87 as well as
the electromagnetic valves 79 and 66 as previously.
Furthermore, during the upward movement of the mobile assembly the
cover 5 causes the table 10 of the station 4 to pivot about the
shaft 14. The covers 5 frees the table when the inclination reached
is sufficient to allow the sealed products to descend by
gravitational force towards the rear table 16 to be discharged;
being freed, the table 10 returns of its own accord to the
horizontal position to await further products to be sealed.
To effect this temporary fixing of the cover to the table, any
suitable mechanical, pneumatic or electrical arrangements may be
used.
In the form of embodiment illustrated in the drawings, the fixing
device is of a mechanical type and may be provided either at only
one side of the table 10 or at both. This device comprises as shown
in FIG. 4, two attaching elements 102 and 103 provided respectively
on the cover 5 and the table 10, one of these elements being
withdrawable. For example, the element 102 is a tooth fast with the
cover 5 and projecting within the cover, whereas the element 103 is
a lever mounted to be pivotable about a shaft 104 of the table 10,
connected to a spring 105 bearing on the latter and provided at the
end with a tooth 106. Whilst the cover 5 descends, its fixed tooth
102 slightly withdraws the mobile tooth 106 which, under the action
of the spring 105, takes this tooth 102 as soon as the cover has
arrived at the lower position. Consequently, the cover 5 can
entrain in its upward movement the lower portion of the table 10
and thus cause it to pivot. When this table reaches the position of
maximum inclination shown in broken lines, the tooth 106 is
released since the lever 103 provided with the tooth is fast with
an extension 107 bearing on a guide ramp 108 of the plate 2, a ramp
which, at a specific level, causes the pivoting of the lever in
opposition to the action of the spring 105.
Such an arrangement can be modified, for instance, by utilizing an
electromagnet arranged in the cover and acting on a push member
situated opposite a catch provided in the table 10. It then
suffices to control the supply of this electromagnet by means of
suitably arranged microcontacts.
* * * * *