EP0311213B1

EP0311213B1 - Method and apparatus for the packing of an object

Info

Publication number: EP0311213B1
Application number: EP19880202216
Authority: EP
Inventors: Jean Paul Soyer
Original assignee: Stork PMT BV
Current assignee: Stork PMT BV
Priority date: 1987-10-06
Filing date: 1988-10-05
Publication date: 1991-07-03
Also published as: DE3863525D1; NL8702435A; EP0311213A1

Description

The invention relates to a method and to an apparatus for packing an object.
From FR-A-2 449 597 an apparatus for packing an object, e.g. a piece of meat is known, which apparatus comprises:

a holder for a first supply roll for a first continuous band of foil,
a holder for a second supply roll for a second continuous band of foil,
an endless conveyor belt, and
an arrangement for the feeding to said conveyor belt of both bands of foil in a mutual relationship such that an object to be packed can be placed on the first band of foil being carried along by the conveyor belt, that the second band of foil is then laid over the object and that the object can then be carried to a first heating device movable towards and away from the conveyor belt for the fusing together of the two bands of foil along a leading edge and a trailing edge.

The apparatus according to the invention is characterized in that said foils are shrink foils,
said conveyor belt can electrostatically attract the first shrink foil,
the first heating device is movable only towards and away from the conveyor belt,
a support surface is fixedly located beneath the operative portion of the conveyor belt in the region of the first heating device, and
conveyor means are provided for carrying a packed object to a second heating device for causing the shrink foils to shrink.
Basis of this apparatus according to the invention is a method for packing an object, e.g. a piece of meat using the following steps:
placing a first sheet of shrink foil on an endless conveyor belt that can electrostatically attract the shrink foil;
carrying along the first sheet with that conveyor belt;
placing the object on said first sheet;
supplying a second sheet of shrink foil in such manner that its leading edge is placed on the leading edge of the first sheet, while leaving the rest of the top surface of the first sheet free;
laying the second sheet over the object, such that the first and second sheets lie one over the other with their edge zones completely encircling the object;
fusing together the overlapping leading edges of the two sheets by means of a heating device which is movable only towards and away from the conveyor belt;
further transporting the first sheet, thereby carrying along the object and the second sheet;
fusing together the overlapping trailing edges of the two sheets by means of said heating device, so that a provisionally packed object is obtained;
separating the fused trailing edge of said provisionally packed object; and
subjecting said provisionally packed object to a heat treatment in such manner that both shrink foils shrink and a packed object is obtained.
The method and apparatus according to the invention are advantageous relative to the cited prior art in that shrink foils are materials that are relatively difficult to handle. The use of a conveyor belt that can attract the shrink foil ensures a reliable carrying of the shrink foil along with the conveyor belt under virtually all practical circumstances.
In a specific embodiment the method may be characterized in that separating the fused trailing edge of the provisionally packed object is performed by allowing said object to tilt downward over the end of the conveyor belt, such that the fused and hence weakened trailing edge is torn away from the continuous bands of foil being fed. This method can be characterized in that the separated object is taken over by a second endless conveyor belt that is placed lower than the first conveyor belt. In this way the tearing off under influence of gravity and hence in a natural manner is ensured.
Accordingly the apparatus for carrying out the method may be characterized by a second endless conveyor belt positioned downstream relative to the first conveyor belt and to the first heating device, which said conveyor belt can take over a provisionally packed object from the first conveyor belt and is placed lower than the first conveyor belt.
To subjecting the provisionally packed object to a heat treatment may preferably be performed by feeding the provisionally packed object through a heating device. In connection therewith the apparatus may be characterized in that the second heating device takes the form of a tunnel, through which the conveyor means extends.
The apparatus may advantageously be characterized in that the conveyor belt consists substantially of reinforced PTFE. Materials of the type of PTFE have the advantage of being highly heat-resistant, reject any adherence or sticking, can be cleansed very readily and are relatively cheap. The excellent heat resistance contributes to a very small time necessary for the first heating device to fuse together the overlapping leading and trailing edges of the tube sheets.
The invention will now be elucidated by reference to the annexed drawings. In the drawings:

figure 1 shows a simplified perspective view of an apparatus according to the invention;
figures 2-11 show highly schematic side views of parts of the apparatus according to figure 1, in which respective processing phases in the packing of an object are illustrated;
figure 12 shows three objects which have been provisionally packed in a multiple execution of the apparatus according to the invention;
figure 13 shows a detail of another embodiment with extra sealing bars extending in a longitudinal direction; and
figure 14 shows a variant of figure 13 with sealing rollers for the formation of sealed side edges.

Figure 1 shows a schematic perspective view of a preferred embodiment of a packing apparatus, which is suitable for the packing of an object in shrink foil. To that end the apparatus 1 comprises a first supply roll 2 for a first continuous band of shrink foil 3, a second supply roll 4 for a second continuous band of shrink foil 5, a first endless conveyor belt 6, a sealing bar 7 for the repeated fusion together of the two bands 3, 5 of shrink foil along one edge, which sealing bar is movable towards and away from the first endless conveyor belt 6.
Under the operative upper portion of the continuous conveyor belt 6, there is located a support surface 8.
In front of the sealing bar 7, a guide roller 9 is disposed in a transverse direction over the endless conveyor belt 6. As will be clear from figure 1, the arrangement is such that the two bands 3, 5 of shrink foil are fed in a mutual relationship to the operative part of the first continuous conveyor belt 6 such that an object to be packed (not shown in figure 1) can be placed on the first band of shrink foil 3 being carried along by the conveyor belt 6, namely on the portion of the first band 3 of shrink foil indicated by numeral 10. Through driving by means of a motor 11, the operative part of the endless conveyor belt 6 is moved in the direction of an arrow 12, carrying with it the foil 3. Thus an object placed on the free part 10 is carried along in the direction of the guiding roller 9, where the bands 3 and 5 come together for the joint packing of a transported object.
The guide roller 9 is held in a frame 13, which also carries a pressure roller 14 which is placed downstream with respect to the sealing bar 7.
The foil bands 3, 5, after unwinding from the supply rolls 2, 4, are brought via the guiding means, which includes loop holders 15, 16, to the conveyor belt 6.
The sealing bar 7 is located, as shown, between the rollers 9 and 14. The frame 13 is movable up and down together with rollers 9 and 14 independently of the sealing bar 7 by means which are not shown.
Located at the end of the first endless conveyor belt 6 is a lower second conveyor belt 17, which can take over an object and carry it through a heating tunnel 18. The second conveyor belt 17 is driven by a motor 19.
The operation of the apparatus 1 according to figure 1 will now be described by reference to figures 2-11. For the sake of clarity of explanation figures 2-11 have been made very schematic. All components are indicated by the same reference numbers as in figure 1.
Figure 2 shows the first phase, in which the apparatus is in a rest position. The rollers 9 and 14 are in their lowered position, while the sealing bar 7 is in its raised position. The bands 3 and 5 extend beneath the rollers 9 and 14 and are carried along by the conveyor belt 6.
In the next phase, illustrated in figure 3, the sealing bar 7 has been moved down and fuses together the relevant edge zone of the foil bands 3, 5.
In this phase an object 20 to be packed is placed on the free portion of the first foil band 3.
In the following phase, shown in figure 4, the sealing bar 7 has been raised, while the frame 13 with the rollers 14 and 9 is still in its lowered position. Meanwhile the object 20 has moved a little further. To allow the object to pass below the rollers 9, 14, the frame 13 is then raised as shown in figure 5, together with the sealing bar 7. The fused leading edge of the two foils is indicated by reference numeral 21. Through the further transportation of the object 20 by the conveyor belt 6, this leading edge 21 is pulled a short distance towards the object 20, as indicated in figure 6, so that the object 20 is gradually covered by the second foil 5.
In the subsequent phase, which is illustrated in figure 7, the object 20 has passed by the rear roller 14 and the frame 13 is moved downwards together with the sealing bar 7.
Then, as shown in figure 8, the sealing bar 7 is again brought onto the foil bands 3, 5 which lie one upon the other, whence the rear edge of the now provisionally packed object is formed by fusion.
In the phase shown in figure 9, the sealing bar 7 has once more been raised.
Figure 10 also shows the second conveyor belt 17, which is positioned a little lower than the first conveyor belt 6. As figure 10 shows, as a result of this arrangement a tilting of the provisionally packed object 20 takes place at the end of the first conveyor belt 6. The fused and hence weakened rear edge 22 now tears as a result of gravitational force, so that the object 20 falls onto the second conveyor belt 17.
As shown in figure 11, this conveyor belt 17 carries the object 20 through a heating tunnel 19, where heating is applied to the foils such that they shrink, in such manner that the object 20 is now definitively packed.
It should be noted that figures 2-11 are meant for explanatory purposes only, and the components are not shown to scale.
The breadth of the foil bands must of course be sufficient to ensure a complete packing of the objects 20.
Figure 12 shows three provisionally packed objects 20, which are being transported by a conveyor belt 23 of a multiple execution of the apparatus according to the invention. The leading edges 21 and the trailing edges 22 have already been fused together. The objects 20 in the situation shown in figure 12 are thus in the processing phase in which they have already passed the sealing bar 7 and are being fed to the heating device or shrinking tunnel 18. The side edges of the foils extend out beyond the objects 20. In practice these edges will come to lie somewhat irregularly over one another, as a consequence of electrostatic attraction and gravity. During the heating in the shrinking tunnel 18, an excellent adhesion is also achieved between the lower foil band 3 and the upper foil band 5 at these side edges.
Figures 13 and 14 show corresponding views of two variants of the packing apparatus according to the invention. These variants each have a common sealing device which is arranged for the formation, after the transversely disposed sealed edges 21, 23 have been formed, of sealed edges extending in the longitudinal direction. To that end the apparatus shown in figure 13 comprises a number of sealing bars 25, which are connected to a frame 26 and are thereby movable up and down by means not shown in the drawing. The sealing bars 25 are provided with a fairly narrow electrically heatable sole, and the foil bands 3 and 5 can thus be provided with a fused sealed edge extending in the longitudinal direction on either side of a provisionally packed object 20. To enable the exertion of a certain amount of pressure, a support surface 27 is located under the operative part of the conveyor belt 6 at the position of the sealing bars 25.
The embodiment according to figure 14 displays sealing rollers 29, which are electrically heated through power supply devices 28, and with which a longitudinally disposed edge seal on either side of the provisionally packed object 20 can be obtained in the manner shown in the figure. These edge seals are indicated by 30 and 31 respectively. In an entirely analogous way to the co-operation between the sealing bars 25 and the support surface 27 in the embodiment according to figure 13, pressure can here be applied by co-action of the heated sealing rollers 29 and a freely rotating roller 32 situated beneath the operative part of the conveyor belt 6.
After leaving the part of the apparatus according to figures 13 and 14, the objects 20 can arrive on the second conveyor belt 17 in the manner shown in figure 10, whereafter the final thermal treatment takes place in the shrinking tunnel 18.
In the figures, the means for moving the frame 13 and the sealing bar 7 up and down are not drawn. These may be known means, such as electric, hydraulic or pneumatic actuators. A central control of the various components can also take place, in which the arrival of an object is established by detectors, which can provide input information to a central control unit. Further control and surveillance means may be present for identifying malfunctions and breakdowns.
The invention offers an apparatus which, with very simple means, is suited for the packing of objects of a variety of sizes, which is simple and can be made in an inexpensive form, and which ensures a high level of reliability and a high processing speed.

Claims

1. A method for packing an object, e.g. a piece of meat using the following steps:
placing a first sheet of shrink foil (3) on an endless conveyor belt (6) that can electrostatically attract the shrink foil;
carrying along the first sheet with that conveyor belt;
placing the object (20) on said first sheet;
supplying a second sheet of shrink foil (5) in such manner that its leading edge is placed on the leading edge of the first sheet, while leaving the rest of the top surface of the first sheet free;
laying the second sheet over the object (20), such that the first and second sheets lie one over the other with their edge zones completely encircling the object;
fusing together the overlapping leading edges (21) of the two sheets by means of a heating device (7) which is movable only towards and away from the conveyor belt (6);
further transporting the first sheet, thereby carrying along the object and the second sheet;
fusing together the overlapping trailing edges (22) of the two sheets by means of said heating device (7), so that a provisionally packed object is obtained;
separating the fused trailing edge (22) of said provisionally packed object; and
subjecting said provisionally packed object to a heat treatment in such manner that both shrink foils shrink and a packed object is obtained.

2. The method according to claim 1, characterized in that separating the fused trailing edge of the provisionally packed object is performed by allowing said object to tilt downward over the end of the conveyor belt (6), such that the fused and hence weakened trailing edge is torn away from the continuous bands of foil being fed.

3. The method according to claim 2, characterized in that the separated object is taken over by a second endless conveyor belt (17) that is placed lower than the first conveyor belt (6).

4. The method according to claim 1, characterized in that subjecting the provisionally packed object to a heat treatment is performed by feeding the provisionally packed object through a heating device (18).

5. An apparatus for packing an object, e.g. a piece of meat, using a method as claimed in any one of the preceding claims, and comprising:
a holder for a first supply roll (2) for a first continuous band of foil (7),
a holder for a second supply roll (4) for a second continuous band of foil (5),
an endless conveyor belt (6), and
an arrangement for the feeding to said conveyor belt (6) of both bands of foil (3, 5) in a mutual relationship such that an object (20) to be packed can be placed on the first band of foil (3) being carried along by the conveyor belt (6), that the second band of foil (5) is then laid over the object (20) and that the object (20) can then be carried to a first heating device (7) movable towards and away from the conveyor belt (6) for the fusing together of the two bands of foil (3, 5) along a leading edge (21) and a trailing edge (22), characterized in that
said foils (3, 5) are shrink foils,
said conveyor belt (6) can electrostatically attract the first shrink foil,
the first heating device is movable only towards and away from the conveyor belt,
a support surface (8) is fixedly located beneath the operative portion of the conveyor belt (6) in the region of the first heating device (7), and
conveyor means (17) are provided for carrying a packed object to a second heating device (18) for causing the shrink foils to shrink.

6. The apparatus according to claim 5, characterized in that the conveyor belt (6) consists substantially of reinforced PTFE.

7. The apparatus according to claim 6, characterized by a second endless conveyor belt (17) positioned downstream relative to the first conveyor belt (6) and to the first heating device (7), which said conveyor belt can take over a provisionally packed object from the first conveyor belt and is placed lower than the first conveyor belt.

8. The apparatus according to claim 5, characterized in that the second heating device (18) takes the form of a tunnel, through which the conveyor means extends.