Variopac - The Fully-Automatic Shrink Foil Packaging System
The fully-automatic, continuously operating Variopac packer is mainly used in the beverage, food and non-food industries for packaging cans, glass and plastic containers. krones provide different versions of this modular designed machine: The containers are either packed into trays without film-wrapping or they are wrapped in film which is then treated with heat and closely shrunk around the containers.
The resulting shrink pack can be additionally reinforced with trays or flat blanks (pads). Moreover the Variopac can also be used to combine several multipacks. Depending on the design, 18 to 100 packs/min. can be produced with the single-lane version, and a maximum of 200 packs/min. can be processed with the double-lane version.
The triple-lane version of this machine was exclusively designed for film processing and has a maximum output of 300 packs/min.
The system advantages of the Variopack mainly are:
- high stability of containers through conveyor lane variants for smooth or petaloid container bases
- secure film wrapping using the overlap principle
- film supply unit with two film reels for efficient production
- modular design ensures high flexibility: packaging with tray, pad and/or film
- short changeover times
- quick start-up thanks to the completely-wired control cabinet
The Variopac Principle of Operation:
1. Container infeed
The containers are conveyed to the machine. Depending on the container type, there are different container infeed versions available such as the lane-guided infeed for special-shaped containers or the combined infeed for loose bottles and multi-packs.
2. Container spacing
Driven by two servodrives, the spacing fingers are pushed between the containers from below separating them. Then, the groups of containers are transferred to pusher bars which guide them through the machine.
3. Carton infeed
The tray or pad blanks are picked up from a storage magazine below the container infeed and placed under the groups of containers.
4. Tray container formation unit
While the packs are being conveyed, guide rails and closing chains fold the tray flaps inward, which are then glued with hotmelt.
5. Film feed
The film is guided using an electronically-controlled film tensioning device. When processing on several lanes the film is divided lengthwise after the dancer. There are two film reels available in the film magazine.
6. Film cutting
In the servodriven film cutting unit the film is cut into equal pieces by a rotating knife. When using printed film, optical sensors make sure that the knife always cuts at the same position. The pieces of film are fixed on a vacuum conveyor which transports them to the packs.
7. Film wrapping
The film is wrapped around the pack using the overlap principle. The leading edge of the film is pulled from the conveyor and then over the pack. A wrapping rod guides the film around the pack. The pack then pulls the film along with it until both ends of the film overlap below the pack.
8. Shrink tunnel
The film, which is wrapped around the pack, is warmed using hot air which causes it to shrink. The packs are conveyed inside the shrink tunnel at a constant speed so that the film can be shrunk in an optimum manner. A cooling zone is integrated in the shrink tunnel just before the transfer point to the conveyor.
The Variopack Machine Modules in Detail:
Film cutting and film wrapping modules
The standard film magazine is equipped for two film reels. Changing from reel 1 to reel 2 as well as splicing of the film ends is done in a very short time. Reel changeover can be carried out during machine operation with an optional equipment for automatic film splicing. Due to the film cutting module's easy access, important parts such as the knife can be quickly reached and replaced. It is driven using a maintenance-free toothed belt.
Thanks to this, tasks such as the lubrication of the film-cutting module surroundings can be omitted. The film-wrapping module performs a decisive role in making sure that the pack is optimally presented. The film overlap on the underside of the pack provides a high degree of pack stability. The servodriven wrapping rod motion is precisely adjusted to the container contour resulting in an accurate and tight film positioning. When there are large height differences between the individual packaging goods, and with high machine outputs, a second guide cam for the wrapping rod is provided.
The stainless-steel shrink tunnel is split up into two heating zones which allow the film to be warmed up gently and which can be adjusted to precisely suit the film's behaviour to temperature.The electrical heating elements are located underneath the shrink tunnel. The air in the shrink tunnel flows past these heating elements and then flows upwards. This means that the packs are treated with hot air from the sides and as a result, an optimum film shrinking result is obtained.
The air guide in the shrink tunnel can be manually altered from the outside and thus has the flexibility needed for the different pack shapes and sizes. When several films and packs are handled on multiple lanes, the air in the shrink tunnel is also guided to the centre of the conveyor chain. Thus, this option also ensures that the packs are handled in a first-class manner.
Variopac Packaging Format Changeover
Changeover to another pack format
The Variopac is flexible and offers a wide range of possibilities. Depending on the model, it can be used to pack identical containers into different types of packs. Or you can chop and change between different container types and shapes within the same packing concept. The corresponding program is selected at a central position using the operating terminal. All changeover variations can be carried out in just a few steps. Changeover is done without the need for tools. Adjustments for new container sizes are performed via a crank and counters. If, for example, shrinkpacks are to be produced with a TFS machine, sliding plates can be placed on the conveyor at the respective positions.
Flexible for the future
The Variopac offers a large range of variations for future changes in packaging types. The basic model FS offers all options, as components such as the pad infeed can be retrofitted for a PFS machine or the tray forming unit can be retrofitted for a TFS machine. Thanks to this modular machine concept, later measures for converting the container infeed and pack discharges are not necessary