Technical Field

The present invention concerns a safety chamber to be used in a packing machine in which sealed packaging containers or carton packages are formed from a packing material web.

Prior Art

Before the packaging containers are formed and filled the packaging material web passes a sterilization part. In the sterilization part the packaging material web first enters an inlet chamber, passes a sterilization bath, containing hydrogen peroxide. After the sterilization or peroxide bath the packaging material web goes into an aseptic chamber. In the aseptic chamber there is an overpressure to assure a sterile environment, while there is an underpressure in the inlet chamber above the peroxide bath. The peroxide bath acts as a liquid seal between the aseptic chamber and the inlet chamber of the peroxide bath. The underpressure in the inlet chamber reduces the risk of peroxide emissions to the environment.

When the packing machine is in production there is sometimes a need for shorter or longer stops, either planned stops or stops due to some malfunction. During stops the peroxide bath is drained and, thus, there will be no seal between the aseptic chamber and the inlet chamber. Due to the different pressures there might possibly, in some occasions in different machine steps, be a risk of hydrogen peroxide emissions.

Summary of the Invention

One aim of the present invention is to further secure that any risk of hydrogen peroxide emissions from the sterilization part of the packing machine is avoided, during any stops in the production.

The present invention is intended for packaging machine forming sealed packaging containers from a packaging material web. The packaging material web is led through a sterilization portion comprising an inlet chamber, a peroxide bath and an aseptic chamber. The packaging material web is led from the inlet chamber through the peroxide bath and then into the aseptic chamber. In the inlet for the packaging material web into the inlet chamber a lip seal is arranged. In production the aseptic chamber is held at an overpressure while the inlet chamber is held at an underpressure. According to the invention a safety chamber is placed in front of the inlet to the inlet chamber, whereby the packaging material web passes the safety chamber before going into the inlet chamber. Further objects and advantages of the present invention will be obvious to a person skilled in the art reading the detailed description below of one embodiment of the invention.

Brief Description of the Drawings The invention will be described more closely below in way of an example and with reference to the enclosed drawings. In the drawings:

Fig. 1 is a schematic view of a portion of the sterilization part of a packaging machine according to prior art;

Fig. 2 is a schematic view of a part of Fig. 1 with an added safety chamber ac- cording to the present invention;

Fig. 3 is a side view of one example of a packaging material web passing through the sterilization part and the safety chamber of previous Figs.; and

Fig. 4 is a plan view of the packaging material web of Fig. 3.

Detailed Description of Embodiments of the Invention

As shown in Fig. 1 a packaging material web 1 is introduced into an inlet chamber 2 through an opening having a lip seal 3. From the inlet chamber 2 the packaging material web 1 goes down into a peroxide bath 5. After the peroxide bath 5 the packaging material web 1 goes into an aseptic chamber 6. In the shown embodiment the packaging material web 1 is lead over a number of guide rolls 9, 10, 11. As used in this description the expression "peroxide bath" is to be construed as a bath comprising hydrogen peroxide.

To eliminate any risk of hydrogen peroxide emissions to the environment outside the packaging machine the inlet chamber 2 is held at a constant underpressure in production. Also the lip seal 3 of the inlet chamber 2 assists in securing elimination of any risk of peroxide emissions. A suction pipe 4 connects by means of a valve 8 the inlet chamber 2 with a main suction pipe 7. In the aseptic chamber 6 there is an overpressure during production.

The peroxide bath 5 will in practice form a seal between the inlet chamber 2 held at underpressure and the aseptic chamber 6 held at overpressure. During short stops, due to some unforeseen event, and normal scheduled stops in the packaging machine, the peroxide bath 5 is drained. Pipes and valves for drainage of the peroxide bath are not shown in the simplified sketches of Figs. 1 and 2. By the drainage the seal between the inlet chamber 2 and the aseptic chamber 6 is removed. This means that the difference in pressure between the inlet chamber 2 and the aseptic chamber 6 will be levelled out. The result may be an overpressure in the inlet chamber 2 and the protection against peroxide emission to the environment is the lip seal 3 at the inlet of the packaging material web 1.

According to the present invention a safety chamber 12 is placed in front of the inlet for the packaging material web 1 into the inlet chamber 2. A lip seal 13 is placed at the inlet for the packaging material web 1 into the safety chamber 12. A suction pipe 14 opens into the safety chamber 12. Said suction pipe 14 is connected to the suction pipe 4 of the inlet chamber 2 by means of a check valve 15, controlling the pressure of the safety chamber 12. The check valve 15 is normally adjustable to control the pressure. By means of the suction pipe 14 it is possible to form an underpressure in the safety chamber 12. The packaging material web 1 will thus pass two lip seals 3, 13 and the safety chamber 12 before going into the inlet chamber 2.

By means of the suction pipe 14 the safety chamber 12 will be held at an underpressure both during stops and in normal production. As stated above, the peroxide bath 5 is drained during stops in the packaging machine. During stops the safety chamber 12 will still be held at an underpressure even if the inlet chamber 2 is held at an overpressure. Thus, any peroxide emissions passing the lip seal 3 of the inlet chamber 2 will be sucked out of the safety chamber 12 without passing to the environment. Any overpressure inside the inlet chamber 2 will act on the lip seal 3 of the inlet chamber 2 in a closing position. Thus, both in normal operation and during stops the lip seals 3, 13 of both the inlet chamber 2 and the safety chamber 12 will protect against peroxide emissions. The protection against peroxide emission given by the two lip seals 3, 13 are further supported by the underpressure in the inlet chamber 2 during normal production and the underpressure in the safety chamber 12 during stops. In the example shown in Figs. 3 and 4 the packaging material web 1 has injection moulded elements such as necks or pouring spouts 16 which are parts of the closure of formed carton packages. Even though the packaging material web 1 is shown as having a number of necks or spouts, a person skilled in the art realizes that the invention can be used also with packaging material webs having no necks. At short stops or normal stops of the packaging machine there is a possibility that a neck 16 is placed in one of the lip seals 3, 13. If a neck 16 is placed in a lip seal 3, 13 that lip seal 3, 13 will possibly not be able to completely seal off the inlet of the packaging material web 1. There might be open parts adjacent the neck 16. If the neck 16 is placed at the lip seal 3 of the inlet chamber 2, the lip seal 13 of the safety chamber 12 and the underpressure of the safety chamber 12 will still eliminate any risk of peroxide emission to the environment. If the neck 16 is placed at the lip seal 13 of the safety chamber 12 the lip seal 3 of the inlet chamber 2 will eliminate any risk of peroxide emission. The safety chamber 12 is designed to have such a length that two necks 16 of the packaging material web 1 never can be at the lip seals 3, 13 of the inlet chamber 2 and safety chamber 12, respectively, at the same time.

If a packaging material web having no necks are used both lip seals 3, 13 and the underpressure of the safety chamber 12 will act against any peroxide emissions.