GB2177923A

GB2177923A - Sterilizing stacked packing containers

Info

Publication number: GB2177923A
Application number: GB08615664A
Authority: GB
Inventors: Hans-Jorg Emmerling; Fritz Neber
Original assignee: Gasti Verpackungsmaschinen GmbH; Jagenberg AG
Current assignee: Gasti Verpackungsmaschinen GmbH; Jagenberg AG
Priority date: 1985-07-16
Filing date: 1986-06-26
Publication date: 1987-02-04
Also published as: DE3525299A1; DE3525299C2; GB8615664D0; FR2585000A1; GB2177923B; FR2585000B1

Abstract

Stacked packing containers (4) before filling and closing them are placed in a sealable sterilizing chamber (11) and subjected to the action of a sterilizing agent such as saturated steam whilst causing the containers to separate from one another by keeping them in a state of suspension, without one contacting another during at least part of the sterilization treatment. The it chamber (1) has inlet and outlet apertures closable by slides (17, 22), a first controllable conduit means (38) to admit a sterilizing agent to the chamber (11) and a second controllable conduit means (45) to admit pressure medium in a pulsating manner to the chamber (11) to effect the state of suspension to separate the containers. The stacked packing containers are suitably plastic cups nestlable one within another. <IMAGE>

Description

SPECIFICATION Process and apparatus for sterilizing stacked packing containers This invention relates to a process and apparatus for sterilizing stacked packing containers, for example plastic cups stacked in one another, before filling and closing them, wherein the packing containers are placed in a sealable sterilizing chamber and, while kept separate from one another therein, are subjected to the action of a sterilizing agent, preferably saturated steam.

German specification OS 31 19037 discloses a system in which, in order to obtain a satisfactory sterilization effect, the packing containers, e.g.

plastic cups, preferably opening downwards, are separated from one another. This separation is effected, for example, with the use of grippers, toothed belts or the like, which grip the packing containers at certain points and pull them apart, or else by constructing the packing containers with projections, notches, ribs, lugs or the like, in such a way that no closed cavity is formed between any two packing containers to be sterilized, thus improving their penetration by the saturated steam used for sterilization. The ribs, lugs or the like provided nearthe mouth form a contact surface with each adjacent container during the sterilization, with the consequent risk that these points of contact will not be sterilized.

The purpose of the invention is to provide means which will ensure in a simple manner that uniform all round sterilization will result.

According to one aspect of the invention there is provided a process for sterilizing stacked packing containers before filling and closing them, the process comprising placing the stacked packing containers in a sealable sterilizing chamber and subjecting them to the action of a sterilizing agent whilst causing the packing containers to separate from one another by keeping them in a state of suspension, without one contacting another during at least part of the sterilization treatment.

For instance using a current or air or steam to effect the suspended state it has been found by using microbiological tests that very uniform sterilization of the packing containers results.

Preferably the packing containers are cups nestable one within another to form a stack, especially plastic cups.

The uniformly satisfactory sterilization effect is readily obtained when the stack of packing containers or cups is caused to vibrate vertically at intervals inside the sterilizing chamber by means of a current of gas or vapour, preferably one of air or steam or a mixture thereof. Expedientiy the containers in the stack are drawn apart at intervals with a concertina-like movement, which may also ensure that the packing containers where they are provided with lugs, ribs or the like, automatically perform a slight rotation in relation to one another, so that the initial contact surfaces between the lugs, ribs or the like and the mouth of the cup no longer coincide, a good sterilization effect thus being obtained at these points of contact likewise.This effect, however, is considerably improved if the current of gas or vapour, for instance air or steam or a mixture thereof is guided onto the packing containers in such a way that they are rotated relative to one another in addition to the state of suspension.

To effect the state of suspension and the rotation of the packing containers, one or more carefully guided jets of steam may be caused to enter the sterilization chamber. The pressure of the gas or vapour to effect rotation is usually higher than the pressure of gas or vapour to effect the sterilization treatment and may be nearly twice as high.

The process to which the invention relates may be carried out in such a manner that the packing containers to be sterilized are in a first stage subjected to the action of steam and in a second stage subjected during the sterilizing treatment to the action of a guided steam jet or jets to obtain the state of suspension and the rotation effect and in a third stage subjected to the action of further steam.

It has been found sufficient if the steam is applied for a period of less than ten seconds, preferably less than five seconds in the first stage and in the second stage for less than four seconds, preferably less than two seconds.

According to another aspect of the invention there is provided an apparatus for comprising a sealable sterilizing chamber to contain stacked packing containers, the sterilizing chamber having inlet and outlet apertures closable by slides to seal the chamber, a first controllable conduit means to admit a sterilizing agent to the sterilizing chamber and a second controllable conduit means to admit pressure medium in a pulsating manner to the sterilizing chamber to enable packed containers within the sterilizing chamber to be kept in a state of suspension, without one contacting another during at least part of the sterilization treatment.

Preferably the second controllable conduit means includes openings in opposed portions of the sterilizing chamber to enable pressure medium in a pulsating manner to be admitted to the said openings.

The second controllable conduit means include channels branching from a main controllable conduit to supply pressure medium to the sterilizing chamber, the said channels passing through the sterilizing chamber wall and terminating in manifolds inside the said chamber.

Preferably the manifolds extend over a side wall of the sterilizing chamber. Desirably the manifolds have outlet apertures directed obiiquely relative to the plane of the side wall of the said chamber.

Preferably the manifolds are so arranged that there are available two opposed manifolds to serve each stack of packing containers to be sterilized.

By way of example a preferred embodiment of the invention will now be described with reference to the accompanying drawings, wherein: Figure 1 is a section through a schematic apparatus for carrying out a process for sterilization of plastic cups, Figure 2 is a side view to an enlarged scale of a sterilizing chamber belonging to the apparatus of Figure 1, Figure 3 is a corresponding plan view of the sterilizing chamber of Figure 2, and Figure 4 is a part sectional view to a much larger scale of two plastic cups stacked one inside the other.

A filling machine of which only a part is shown in Figure 1 and which includes an apparatus for the performance of a process embodying the invention contains a conveyor means 1 including a conveyor belt 2 by which stacked plastic cups are fed into position from a stack which can be delimited by a stop 3. The plastic cups 4 are conveyed in stacks, by means of conveyor means 1 moving in the direction shown by the arrow 5, to a lifting device 6 having receiving arms 7 by which the stacks are moved upwards by means of the lifting device 6 in the direction shown by the arrow 8 and piaced in a vertical position of readiness inside a stacking magazine 9.

Underneath is a sterilization chamber 11 into which the plastic cups 4to be sterilized therein can be introduced from above. The sterilization chamber 11 is positioned above a filling machine 13, in which the sterilized plastic cups 4 are kept in readiness in an unstacking magazine 14. The plastic cups are extracted individually from the unstacking magazine 14, rotated through 180 in the sense shown by the arrow to invert them and inserted in an apertured conveyor belt 15 belonging to the filling machine 13 and shown schematically. The lowest plastic cup 4 of a stack inside the stacking magazine 9 rests on a slide 17 which closes the inlet aperture of the sterilization chamber 11 and which can be displaced sideways by the aid of a toggle lever, not shown, so that it releases the inlet to the sterilization chamber 11.The toggle lever is pivotably articulated by the end of one of its arms to the slide 17, while the end of its other arm is movable sideways by the aid of a device not shown in detail, such as a motor.

When the slide 17 releases the upper inlet aperture of the sterilization chamber 11 the plastic cups 4 fall into the said sterilization chamber 11, after which the latter is re-closed. The closing operation is effected by moving the slide 17 and a corresponding slide 22 mounted on the bottom of the sterilization chamber 11 into the position shown in Figure 1, after which clamping elements not shown, such as eccentrics, can be moved into their clamping position by a device likewise not shown. In this position the eccentrics press the relevant slides 17, 22, against a packing 24 in the top and bottom respectively of the sterilization chamber 11.

In the lower slide 22 is an oblique bore 25 which leads to a connection 26. A pipe 27 communicating with the connection 26 contains two valves 28, 29, which can be opened and closed by the aid of two control devices 31 and 32 respectively. The valve 28 leads to a vacuum pump, while the valve 29 serves for the discharge of condensate into the atmosphere.

The sterilization chamber 11 and also the unstacking magazine 14 are surrounded by a housing 30 into which leads a connection 34 immediatelyfollowed bya pipe 35, which is only shown schematically and which contains a valve 36 with a control device 37 for the supply of steam, of which the pressure may amount, for example, to 3.5 bar. To the wall 40 of the sterilization chamber 11 is connected a further pipe 38 containing two valves 39,41. With the valves 39, 41, are associated control devices 42,43, enabling the valves 39,41, respectively to be opened and closed. The valve 41 serves for the admission of sterile air, while the valve 39 serves for the admission of steam, of which the pressure amounts, for example, to 3.5 bar.

As may be seen from Figure 2, the wall 40 of the sterilization chamber 11 is provided with individual apertures 44 distributed over the periphery and/or the length of the sterilization chamber 11 and enables the steam to be introduced into the said sterilization chamber 11 in separate currents.

The sterilization chamber 11 also contains a connection 45 for a supply pipe 46, through which steam can be fed in at high pressure, e.g. 6 bar, in a pulsating manner. The pipe 46 contains a valve 47 with a control device 48. The connection 45 communicates via channels 49 with manifolds 51 which extend substantially over the entire height of the sterilization chamber 11 and are provided with outlet aperture 52 slanting upwards.

Figures 2 and 3 show a sterilization chamber 11 which is designed for eight stacks of cups and in which the arrangement of the manifolds 51 and the outlet apertures 52 can be clearly seen. Each two manifolds, diametrically opposite to each other, are associated with one stack of cups. The outlet apertures 52 are also arranged in such a manner that steam emerges in a direction approximately tangential to the plastic cups, so that the said cups, in a manner described in greater detail later, are not only caused to assume a suspended position in which they are separated from one another but are at the same time rotated relative to one another, as a result of which the said plastic cups 4 are thoroughly sterilized all round.

The apparatus constructed as described above operates as follows: The slide 17 is first of all displaced laterally, to give passage through the upper inlet aperture of the sterilization chamber 11. This causes the plastic cups 4 positioned in the stacking magazine 9 to slide into the interior of the sterilization chamber 11, which thus becomes non-sterile. The upper slide 17 is then moved back into the position shown in Figure 1, after which the eccentric for the slide 17 presses the latter against the packing 24. The lower slide 22 is already pressed against it, so that the sterilization chamber 11 is now sealed off inside the housing 30. The control device 31 now opens the valve 28, so that the sterilization chamber 11 is evacuated via the pipe 27. After a certain time and by the aid of control device not shown in the drawings and the control device 42 the valve 39 is opened, so that hot stean; can now penetrate into the interior of the sterilization chamber 11, the valve 28 still being open at this moment. The valve 28 is closed shortly afterwards, so that pressure can now build up in the sterilization chamber 11, causing an increase in the steam temperature. As soon as the desired temperature is reached in the sterilization chamber 11,which can be verified with a thermometer probe or in accordance with the time elapsing, the valve 39 re-closes. The pipe 35 is continuously fed with steam for the pre-heating of the sterilization chamber 11.The steam for the sterilization of the cups 4 enters through the pipe 38 and is evenly distributed to the sterilization chamber 11 through the perforations 44 in the wail.

The vaporization phase is followed by an additional steam pulsation via the supply pipe 46, or in other words, jets of steam are fed into the sterilization chamber 11 at intervals. This causes the stack of plastic cups to vibrate vertically, so that they are apart at intervals concertina-wise, the current of steam thereby causing the cups to float above one another, as it were, resulting in a very uniform sterilizing action. Tests have shown that the cups are then substantially free of germs.The special arrangement of the manifolds 51 and outlet apertures 52, i.e. slanting upwards and approximately tangential to the stack of cups, ensures that these latter will not only move apart from one another, thus leaving a greater distance between their mutually facing portions, but at the same time rotate relative to one another, so that previous contact surfaces between mutually adjacent plastic cups will no longer cover one another over. After the steam pulsation phase the plastic cups 4 can be subjected to the action of further steam.

The valve 28 is then re-opened by the aid of the associated control device 31, so that the steam and any condensate which has formed can be evacuated out of the sterilization chamber 11. After a short time the valve 41 is opened by means of the associated control device 43: cold sterile air now flows through the sterilization chamber 11 into the pipe 27 to the valve 28, the plastic cups 4thus being re-cooled.

This prevents the temperature prevailing on the surface of the plastic cups from being transmitted into their walls. This rapid cooling by the sterile air offers the advantage of preventing any deformation of the plastic cups and of enabling the process to be carried out as rapidly as possible. The valve 28 is then closed, the valve 41 remaining open.

A certain excess pressure now prevails in the sterilization chamber 11 and is maintained by the sterile air. As soon as a contact on the end of the unstacking magazine 14 shows that there are now only a few plastic cups left in this latter the eccentrics for the lower slide 22 are released, the said slide being displaced laterally by the aid of the associated adjusting device, so that the plastic cups 4 can now drop out of the sterilization chamber 11 into the unstacking magazine 14. At this moment the entire interior of the sterilization chamber 11 is sterile, so that no germs can enter the filling machine 13. This effect is further assisted by the maintenance of a slight excess pressure of sterile air before the opening of the lower slide 22.

At the bottom of the unstacking magazine 14 the plastic cups 4 inside the housing 30 are extracted individually, gripped by a holding device, not shown in the drawings, and turned round. The openings of the plastic cups 4 are now at the top, so that they can be placed in the apertured conveyor belt 15 of the filling machine 13, from which position they are then conveyed to a filling station.

Figures 2 and 3, illustrating an eight-part sterilization chamber 11, make evident the three stages in the sterilizing process, i.e. the vaporization in the three left-hand chambers, marked A, the presence of pressure pulses inside the three middle chambers, marked B, and the further vaporization, and the position of the plastic cups, prior to delivery, in the chambers marked C. Figure 2 clearly shows (see reference strokes 55) how the plastic cups 4 rotate to a different position before and after the application of steam jets.

In order to make the effect of the process still clearer Figure 4 shows two cups 4 stacked one inside the other, one plastic cup 4 being shown as a side view and the other in section. It may be seen that the side walls of the cups are a certain distance apart, so that from this point of view there is no obstacle to the introduction of the steam into the sterilization chamber 11. On one side of their cylindrical portion 50 the cups are provided with separate stacking lugs 53, each of which comes to rest on the edge 54 of the other plastic cup. Between the individual stacking lugs 53, therefore, steam can enter the intermediate space between two plastic cups. In order to improve the penetration of the steam still further the plastic cups may be caused to vibrate vertically by the steam jet and the steam jet may also act on them in such a way as to cause them to rotate relative to one another. The contact surfaces between the stacking lugs 53 and the adjacent plastic cup thus no longer cover each other over, so that at those points likewise a very satisfactory sterilization effect is obtainable.

In principle the generation of pressure pulses could be effected, for instance, with compressed air instead of with steam, although it would then have to be accepted that the plastic cups would cool down again.

Claims

1.A A process for sterilizing stacked packing containers before filling and closing them, the process comprising placing the stacked packing containers in a sealable sterilizing chamber and subjecting them to the action of a sterilizing agent whiist causing the packing containers to separate from one another by keeping them in a state of suspension, without one contacting another during at least part of the sterilization treatment.

2. A process according to Claim 1, wherein the packing containers are cups nestlable one within another to form a stack.

3. A process according to Claim 2, wherein the cups are plastic cups.

4. A process according to any preceding claim, wherein the sterilization treatment comprises a saturated steam treatment.

5. A process according to any preceding claim, wherein the stack of packing containers is caused to vibrate vertically at intervals inside the sterilizing chamber by means of a current of gas or vapour.

6. A process according to any preceding claim, wherein the current is one of air or steam or a mixture thereof.

7. A process according to any preceding claim, wherein the packing containers are also during the sterilization treatment rotated relative to one another by a guided current of gas or vapour.

8. A process according to Claim 7, wherein the current producing the rotation is one of air or steam or a mixture thereof.

9. A process according to Claim 7 or Claim 8, wherein the pressure of the gas or vapour to effect rotation is higher than the pressure of gas or vapour to effect the sterilization treatment.

10. A process according to Claim 9, wherein the pressure of the gas or vapour to effect rotation is nearly twice as high as the pressure of gas or vapour to effect the sterilization treatment.

11. A process according to any preceding claim, wherein the packing containers to be sterilized are in a first stage subjected to the action of steam and in a second stage subjected during the sterilizing treatment to the action of a guided steam jet or jets to obtain the state of suspension and the rotation effect and in a third stage subjected to the action of further steam.

12. A process according to Claim 11, wherein in the first stage steam is applied for less than 10 seconds.

13. A process according to Claim 12, wherein in the first stage steam is applied for less than 5 seconds.

14. A process according to any preceding claim, wherein in the second stage the steam treatment includes pulsations for a period of less than four seconds.

15. A process according to Claim 14, wherein in the second stage the pulsation steam treatment is conducted for less than two seconds.

16. A process for sterilizing stacked packing containers substantially as hereinbefore described and with reference to the accompanying drawings.

17. An apparatus for carrying out the process claimed in Claim 1,the apparatus comprising a sealable sterilizing chamber to contain stacked packing containers, the sterilizing chamber having inlet and outlet apertures closable by slides to seal the chamber, a first controllable conduit means to admit a sterilizing agent to the sterilizing chamber and a second controllable conduit means to admit pressure medium in a pulsating manner to the sterilizing chamber to enable packed containers within the sterilizing chamber to be kept in a state of suspension, without one contacting another during at least part of the sterilization treatment.

18. An apparatus according to Claim 17, wherein the second controllable conduit means includes openings in opposed portions of the sterilizing chamber to enable pressure medium in a pulsating manner to be admitted to the said openings.

19. An apparatus according to Claim 17 or Claim 18, wherein the second controllable conduit means include channels branching from a main controllable conduit to supply pressure medium to the sterilizing chamber, the said channels passing through the sterilizing chamber wall and terminating in manifolds inside the said chamber.

20. An apparatus according to Claim 19 wherein the manifolds extend over a side wall of the sterilizing chamber.

21. An apparatus according to Claim 19 or Claim 20, wherein the manifolds have outlet apertures directed obliquely relative to the plane of the side wall of the said chamber.

22. An apparatus according to any one of claims 19 to 21, wherein the manifolds are so arranged that there are available two opposed manifolds to serve each stack of packing containers to be sterilized.

23. An apparatus for sterilizing packing containers before filling and closing them substantially as hereinbefore described and illustrated by the accompanying drawings.