The invention relates to a method for the portioned packaging of liquid and/or pasty products by means of a packaging machine by the product being fed via at least one inlet of a metering chamber, being metered in the metering chamber by means of at least one metering member with an axially shiftable metering piston to form at least one product portion, and the at least one product portion being fed via at least one metering outlet to a package wherein the metering chamber is operated in a continuous flow in at least one operating state of the packaging machine from the following group                downtimes of the packaging machine,        start-up of the packaging machine, and        operation of the packaging machine,        
by the product being removed entirely or partially from the metering chamber via at least one outlet and being recirculated. The invention furthermore relates to a packaging machine, which is suitable in particular for carrying out such a method, for the portioned packaging of liquid and/or pasty products, with at least one metering chamber with at least one inlet in order to meet the product to the metering chamber, at least one metering member which is arranged in the metering chamber and has an axially shiftable metering piston for metering at least one product portion, and with at least one metering outlet in order to feed the product portion to a package, wherein the metering chamber furthermore has at least one outlet which leads into a recirculation line, wherein the product can be supplied to the metering chamber via the at least one inlet and can be entirely or partially removed via the at least one outlet into the recirculation line.
Packaging machines of the abovementioned type are known in particular for packaging metered product portions of pasty products, such as, for example, butter, margarine and the like, and are commercially available in the applicant's business under the trade name “M8000”. Packaging machines of this type have one or else more metering chambers which are arranged in parallel and to which the pasty product is cyclically supplied via one inlet (each). A metering member, for example in the form of an axially shiftable piston, is located in the metering chamber or the metering chambers and is capable of discharging the pasty product out of the previously filled metering chamber via a metering outlet of same, after which the metered product portion is fed to a package, such as, for example, an upwardly open blank of a wrapper, a cup or the like, which package is guided past the metering chamber, for example, in lifting cells arranged below the metering outlet of the metering chamber. Such packaging machines have also proven best, not least because of their high degree of sturdiness and efficiency, for packaging pasty products from the foodstuffs sector that have to satisfy exacting requirements imposed on hygiene.
In the meantime, it has been shown that some pasty products in the inoperative state have a tendency to crystallize out relatively rapidly, wherein mention may be made by way of example of some types of margarine in which, in particular in the heated, slightly viscous to liquid state, the oil-in-water emulsion separates out very rapidly and oil or fat crystals form which are not (no longer) dissolved in the aqueous “solvent”. The same applies, for example, to ice cream if, in the inoperative state, i.e. when the pasty mass is not stirred or moved in some other way, especially the aqueous phase crystallizes out.
Furthermore, it has been shown that the abovementioned problem can be manifested in the case of packaging machines of the type in question in that, in the event of processing such products which are highly sensitive in respect of separating out or crystallizing out, in particular during temporary and also brief downtimes of the packaging machine or during restarting of same, erroneous meterings and/or defective product portions occur which have to be sluiced out and disposed of because the product residues remaining in the packaging machine no longer have the required quality. Consequently, the packaging machine should be entirely flushed prior to each start-up, which is complicated and leads to undesirable downtimes. The same may be the case in the event of very slow metering and an associated, very slow supply of product into the metering chamber, wherein slow meterings may, on the other hand, be required if the pasty product is also sensitive to the mechanical forces brought about thereon in the metering chamber by the metering member. On the other hand, the packaging machine should, however, nevertheless be easy and rapid to clean without having to be disassembled and reassembled in a complicated manner. The structural design of the packaging machine should in particular permit what is referred to as “Cleaning In Place” (“CIP”) in order, for example in the case of product changes or else for hygiene reasons, to be able to clean at least those components of the packaging machine which enter into contact with the product at regular intervals in situ.
U.S. Pat. No. 3,979,012 A describes a packaging machine of the type in question which is provided in particular for packaging sensitive, pasty products, such as margarine, that have a tendency to crystallize out. The known packaging machine comprises two metering members in the form of two metering pistons which, in one rotary slide each, which forms the metering chamber, are shiftable in the axial direction of the rotary slide. The metering chambers of the rotary slides lead into a common outlet nozzle, at the outlet-side end of which an outlet rotary valve is arranged. In order to keep the product always in motion during the operation and to thereby counter an untimely crystallizing out, the product is always circulated, wherein the circulating line has a line portion from where the product enters the rotary slide, which is arranged downstream of said line portion, in order to be fed to a package via the outlet nozzle by shifting of the metering piston guided displaceably in said rotary slide. Consequently, in particular during downtimes of the packaging machine, for example at night, or else in the event of only brief operating interruptions, there is, as before, the problem that the product crystallizes out in the rotary slides forming the metering chambers, whereupon the rotary slides have to be completely disassembled, cleaned and reassembled because even “CIP” cleaning is not possible in situ. The latter is caused especially by the fact that the rotary slides cannot be flushed through with a cleaning medium either in the position in which they open toward the line portion of the circulating line or in the position in which they open toward the outlet nozzle, particularly since the product also passes between the outer circumferential surface of the rotary slides, which is always in contact with said product, and the bearing shells of said rotary slides which cannot be cleaned at all in the fitted state.
The same applies very substantially to a metering device, which is known from WO 2007/118676 A1, for liquid or pasty products, which metering device can be used, inter alia, in packaging machines. Similarly as in the US document mentioned above, the metering device has a line portion through which the product always flows, wherein a metering chamber branches off from the line portion in the radial direction. In this case, the metering member is arranged in the line portion and comprises a metering piston with a piston rod which is of hollow design and, at its free end, has an inlet opening for feeding in a sterilizing agent, and also a valve spindle which is likewise hollow and surrounds the piston rod on the outer or circumferential side. That region of the metering device which is located within the valve spindle does not come into contact with the product and serves exclusively for adding the sterilizing agent during each metering operation. During a metering operation, a valve body, which is arranged on the outer side of the valve spindle, is brought into sealing contact with the mouth region of the branching of the line portion into the metering chamber and the metering piston is pushed into the metering chamber in order to press the product portion located there out of the metering chamber. Apart from the fact that the known metering device, because of the fixedly predetermined size of the metering chamber, is capable only of metering a corresponding, fixedly predetermined product portion, there is in particular the disadvantage, even in this case—if sensitive products of the abovementioned type are intended to be processed—that, even during short downtimes, the product crystallizes out in the metering chamber, after which the metering chamber has to be cleaned.
GB 2 450 955 A describes a dispenser for metering fluid substances, the dispenser having one or more metering members. If a plurality of metering members are provided, the latter are arranged in one line portion each of a product-conducting line into the two opposite ends of which the product is fed, and therefore a partial flow of the product provided for the inner metering member passes the respectively outer metering members. Each metering member then meters a desired product portion before said product portion is removed via a respective metering outlet. The metering members are arranged in the form of a type of piston/cylinder arrangement projecting into the product-conducting line portion. However, processing of in particular products of the abovementioned type that are sensitive to rapid crystallization is not possible by means of the known dispenser for a number of reasons. Although, firstly, some metering members—the outer metering members—are operated in continuous flow because of their series connection, a desired partial flow which passes said metering members can nevertheless not be set since said partial flow is fixedly predetermined by the necessary metering volume of the middle metering member which cannot be operated in continuous flow. Secondly, in the event of even only short downtimes of the dispenser, the product which is sensitive in respect of crystallizing out would directly crystallize out because said product can only be removed from the line portion equipped with the metering members via the metering outlets, from where said product would have to be discarded.
WO 01/14209 A1 finally involves a hygienic dispenser which is provided for the metered dispensing of viscous foodstuffs and in which the foodstuffs are intended always to be kept in a continuous flux during the operation and during downtimes. The dispenser has a metering chamber which accommodates a cylinder with a piston shiftable axially therein, as the metering member. The liquid or viscous product passes via an input-side passage into the dispenser and from there via an inlet valve into the metering chamber where said product is metered by means of the piston. The product then leaves the metering chamber via an outlet valve arranged next to the inlet valve in the radial direction and passes into an output-side passage which is arranged parallel to the input-side passage and is connected to one or more metering tips which are inserted interchangeably into the output-side passage. The output-side passage finally leads downstream of the metering chamber provided with the metering piston into a recirculation line, wherein the liquid—viscous foodstuff can be entirely or partially recirculated by only one product portion being transferred from the output-side passage into the metering tips while the rest of the product passes downstream of the output-side passage into the recirculation line and is fed again from there to the input-side passage. However, it has proven disadvantageous firstly that circulation of the product through the metering chamber during downtimes of the dispenser appears to be possible only when the metering piston remains continuously in operation because the piston stroke is absolutely necessary for pumping the product through the metering chamber, which in turn means that the setting of a desired ratio of metered and recirculated product is not possible. Secondly, the known dispenser does not permit what is referred to as CIP cleaning, during which said dispenser could be flushed by means of a cleaning fluid without having to disassemble the dispenser. Said disassembly is caused by the fact that the metering piston which enters into contact on its lower end side with the product located in the metering chamber, if the metering chamber including its feed and removal lines is flushed with a cleaning fluid, can also come into contact only on its lower end side with the cleaning fluid, and therefore product residues which have been concentrated radially between the metering piston and the circumferential wall of the metering chamber after a plurality of piston strokes cannot be completely removed, as would absolutely be necessary, however, for foodstuff applications.
The invention is based on the object of developing a method for the portioned packaging of liquid and/or pasty products of the type mentioned at the beginning and a packaging machine of the type in question that is suitable in particular for carrying out such a method, in a simple and cost-effective manner to the effect that the problem of products sensitive to crystallizing out can be effectively countered while at least very substantially avoiding the aforementioned disadvantages, wherein in particular also simple “CIP” cleaning is intended to be ensured.