Lock device for adding and removing containers to and from a vacuum treatment chamber

A lock device for adding and removing containers to and from a vacuum treatment chamber includes carrier plates for the containers. The carrier plates are fastened to revolving transport chains and are transported through lock channels provided in straight sections along the transport chains. The carrier plates also achieve a sealing effect with the channels as they are moved past suction or ventilation openings in the lock channels to form a differential pressure stage.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority of International Patent Application No. PCT/EP2008/010848, filed Dec. 18, 2008, which application claims priority of German Application No. 102008007629.5, filed Feb. 4, 2008. The entire text of the priority application is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The disclosure relates to a lock device for continuously adding and removing containers to and from a vacuum treatment chamber.

BACKGROUND

Such lock devices are required e.g. for vacuum-supported coating processes, e.g. to increase gas-tightness of PET bottles which to this end are usually treated in a vacuum of about 10 to 40 mbar. For this, continuous locking in and out is indispensible for an economical manufacturing process.

A generic lock device is known e.g. from EP 0943699 B1. This lock comprises a revolving housing with a lock chamber wheel rotatably mounted therein in which lock chambers with openings for loading and unloading containers to be locked are provided on the circumference.

The revolving housing comprises suction pipes for evacuating the lock chambers which are atmospherically sealed from each other by circumferential seals on the lock wheel. The lock chambers between the charging and the discharging station, respectively, in the outer room and the evacuated treatment room form a differential pressure stage, the lock chamber pressure being reduced revolving in the direction of the treatment room, from the atmospheric pressure usually prevailing in the outer room to the pressure prevailing in the treatment room.

However, due to the complicated manufacture of the revolving housing and the lock chamber wheel, a subsequent adaptation of the device to different container sizes and shapes is expensive or not possible at all. To be able to also for large containers provide sufficiently large lock chambers in a number sufficient for the differential pressure stage, it is moreover necessary to correspondingly increase the diameter of the lock wheel. This involves a wide structural shape which might be undesired.

Another lock device known from DE 27 47 061 A is used to lock tapes into or out of a vacuum coating chamber through a pressure stage section. The lock device comprises several fixed lock chambers arranged one behind the other and separated from each other with slit-like diaphragms. The tape to be coated is transported through the slit diaphragms and the lock chambers on a backing tape. To be able to generate a drop of pressure between the chambers, the diaphragms must be adapted to the cross-section of the backing tape and the tape to be coated. Such a device, however, is not practicable for locking in and out containers, as these, in contrast to a tape, do not comprise a constant cross-section seen in the moving direction, or as gaps between the individual bottles are inevitable.

SUMMARY OF THE DISCLOSURE

It is an aspect of the present disclosure to provide a generic lock device which permits continuous adding and removing of containers to and from a vacuum coating room into a room with atmospheric pressure, which, however, does not comprise the aforementioned disadvantageous restrictions.

This aspect is achieved with the present lock device. Accordingly, the lock comprises a revolving transport means comprising straight sections with carrier plates arranged at the transport means at distances for holding the containers, with lock channels at least partially extending along the straight sections through which the containers are transported by transport means, the carrier plates being embodied so that they achieve such a sealing effect with the channel walls that a drop of pressure can be generated in the lock channels.

The lock device can be flexibly and inexpensively adapted to changed demands by exchanging the carrier plates and/or changing the distance between the carrier plates.

Advantageously, a suction opening or a ventilation opening is embodied in the channel wall. Thereby, the lock channel can be evacuated or ventilated without having to provide disturbing conduits in the channel.

In one advantageous embodiment, the carrier plates are, at least in sections, thicker than the clearance of the suction opening or the ventilation opening at the side facing the suction opening or the ventilation opening, so that the opening can be closed by the carrier plates. Thus, pressure compensation in the lock channel can be timed.

In the moving direction of the transport means, further suction openings or ventilation openings are preferably arranged at a distance. This permits suction or ventilation with different pressures section by section.

It is particularly advantageous to be able to generate step-like pressure differences between the front and rear sides of the carrier plates. This permits to displace regions of different pressures within the lock channel with the carrier plates.

Favorably, the lock channel is embodied as differential pressure stage in which the pressure is reduced towards the vacuum treatment chamber. Thereby, the bottles can be stepwise adapted to the vacuum in the treatment chamber.

In a particularly advantageous embodiment, the carrier plates each comprise at least one seal surrounding the edge and lying against the channel wall. Thereby, the sealing effect of the carrier plates can be improved.

It is furthermore advantageous to embody the transport means in the form of two chains, toothed racks, tension bars or belts arranged one upon the other. This permits uniform power transmission to the carrier plates and prevents the plates from being inclined in the lock channel.

In a particularly advantageous embodiment, the carrier plates comprise rollers which support the plates at the channel wall. It is thereby prevented that the plates are tilted or get jammed. Moreover, the rollers take care that the plates maintain an essentially constant distance to the channel wall over the complete circumference and a uniform sealing effect is thus achieved.

Favorably, the carrier plates are centrically fixed to the transport means. Thereby, a moment on the support rollers can be prevented.

Advantageously, the channel wall comprises plate-like lateral segments which are connected by half bowls. This permits a good sealing effect as well as an inexpensive manufacture and adaptation to different bottle sizes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The lock device according to the disclosure represented inFIG. 1comprises a transport means in the form of two chains3,5arranged one upon the other (inFIG. 1, only the upper chain3is represented), which move around two chain wheels7,9in the direction of the arrow A and at which carrier plates11for holding bottles13to be treated are provided at regular distances B in an essentially orthogonal position to the moving direction. Most of the straight sections of the chains3,5extend through lock channels15,17.

According toFIG. 2, the chain wheel7is located in an outer room19at normal atmospheric pressure, while the chain wheel9(not represented inFIG. 2) is arranged in an evacuated treatment chamber21. The bottles13are supplied in a charging region23and removed again in a discharging region25(charging and discharging are not represented).

In the wall27of the lock channel15, suction openings29are provided at a distance B to which suited pumps, e.g. vacuum pumps (not represented) are connected, so that the respective applied pressure p is reduced in the moving direction A.

According toFIG. 1, also at a distance B, ventilation openings31are provided in the wall27of the lock channel17. Suited pumps can be connected to these, so that the respective applied pressure p is increased in the moving direction A. However, it is also possible to passively ventilate the lock channel17through the ventilation openings31, e.g. via suitably dimensioned connections (not represented) to the outer room19or via a short circuit to the inlet channel15to recycle the vacuum.

As can be taken fromFIGS. 3 and 4, the chains3,5consist of chain segments3a,5a, of which the ends are each centrically attached to the carrier plates11. To this end, one chain connection link33each is provided at the front sides (facing the moving direction A) and rear sides of the carrier plates11.

Each carrier plate11comprises one clamp35each for holding the bottles11on the plate front side and on the plate rear side, as well as rollers37that support the carrier plates at the walls27of the lock channels15,17. The carrier plate11furthermore comprises two surrounding grooves39which, as shown inFIG. 5, receive each one seal41lying against the channel wall. The distance between the grooves41is enlarged on the side of the carrier plate11facing the suction openings29or ventilation openings31, respectively. Thereby, a sealing region43is provided at the carrier plate11of which the length C (in the moving direction A) is larger than the clearance D of the suction opening29or the ventilation opening31(inFIG. 5, suction openings are shown by way of example).

The chain segments3a,5aare preferably embodied as roller chains. Chain segments3a,5aof a uniform length can be easily manufactured with them and fixed by means of the chain connection links33. However, it is just as well possible to embody a transport means according to the disclosure on the basis of toothed racks, tension bars or belts.

The chain wheel7is preferably mounted to be movable. In this manner, the tension of the chains3,5can be adjusted. Grooves44into which the carrier plates11engage are provided at the circumference of the chain wheels7,9, at a distance B. The chain wheels7,9can moreover engage in the links of the chains3,5. If toothed racks are used instead of the chains3,5, they can be driven by means of toothed wheels.

The lock channels15,17each comprise two rectangular plates45which are bolted with two half bowls47with a semicircular cross-section. This permits a flexible, modular assembly. The resulting channel cross-section moreover permits a good sealing effect of the carrier plates11. The lock channels15,17, however, could also have a different cross-section and/or be composed of a different number of individual parts or made of one piece, respectively. The lock channels15,17are preferably made of metal, in particular of hardenable steel.

The suction openings29of the lock channel17are preferably embodied as borings, but they can also have another, e.g. rectangular cross-section. InFIG. 2, five suction openings29each are arranged one upon the other. However, a different number is also possible. It is decisive that all suction openings29can be simultaneously closed by the sealing region43of the carrier plate11. This is also true for the ventilation openings31of the lock channel19, i.e. the suction openings29and the ventilation openings31are arranged and shaped such that the carrier plates11drive over them simultaneously and close them in the process.

InFIG. 2, two groups of five suction openings29each are represented in the moving direction A. As is illustrated in detail in the functional description, these groups correspond to two differential pressure stages, like the two ventilation openings31shown inFIG. 1. The number of differential pressure stages, however, can be different, as is shown inFIG. 5. Equally, the number of pressure stages on the suction side and on the ventilation side can differ.

In the embodiment represented in the figures, the pressure stages are based on the suction or ventilation through the openings29,31in the channel wall27. As an alternative, however, it is also conceivable to replace the openings29,31by an internal suction or ventilation in the lock channels15,17, e.g. by suited conduits in the lock channels15,17and/or in the channel wall27.

The carrier plates11are preferably made of metal, such as special steel or aluminum, or of plastics, and their shape is adapted to the cross-section of the lock channels15,17, such that a uniform sealing effect is achieved by the seals41or a sealing gap (not represented).

The seals41are embodied as lip seals. The number of seals, however, can deviate from the shown embodiment upwards or downwards. As an alternative, other sealing means could be also used, or the carrier plates11could be adapted to the cross-section of the lock channels15,17so precisely, that a sufficient sealing effect, including the sealing region43, is also achieved without the seals41, e.g. with a sealing gap.

The carrier plates11are supported in the lock channels15,17by the rollers37, such that the plates11do not tilt or get jammed and the plates11maintain an essentially uniform distance to the channel wall27over the complete circumference to achieve a uniform sealing effect e.g. with a uniform sealing gap in this manner. The represented number and position of the rollers37is given by way of example and depend, among other things, on the position of the suction openings29. Outside the lock channels15,17, the carrier plates11do not have to be guided at the rollers37.

The chain connection links33are arranged centrically on the carrier plates11. Thus, the chains3,5centrically act at the carrier plate11at the top and bottom to avoid a moment on the support rollers37. If other drive means are employed, such as e.g. toothed racks, tension bars or belts, the connection links33are embodied to match these.

The clamps35are arranged such that the bottles13are held between the upper chain3and the lower chain5.

Below, the functioning of the lock device shown in the embodiment will be illustrated with reference to the adjacent bottles13a,13bshown inFIG. 5. Here, “adjacent” bottles means that these are subjected to essentially the same pressure in the lock channel and are separated from “non-adjacent” bottles with the carrier plates11a,11bby a drop of pressure.

The chains3,5are driven continuously, e.g. by a motor acting on the chain wheel7(not represented). At each of the suction openings29a,29b,29c, a vacuum p1, p2, p3is continuously applied, where p1>p2>p3.

The bottles13a,13bto be treated are handed over to the clamps35of the carrier plates11a,11bwith a suited charging station (e.g. a common star wheel) in the region23and transferred into the lock channel15on the inlet side. There, the bottles13a,13bare first under normal atmospheric pressure. As soon as the front plate11bpasses the first suction opening29a, the region between the plates11aand11bis in communication with the suction opening29aand is evacuated maximally to a suction pressure p1, while the chain transport is simultaneously continued. This evacuation step is continued until the rear plate11adrives over the first suction opening29aand closes the same thereby. As the carrier plates11and the suction openings29are essentially arranged at the same distance B with respect to each other, the front plate11bsimultaneously drives over the second suction opening29b.

As soon as the front plate11bnow passes the second suction opening29b, the region between the plates11aand11bis in communication with the suction opening29band will be evacuated maximally to the suction pressure p2, until the rear plate11adrives over the second suction opening29band closes the same thereby. Thus, the region between the plates11aand11bis evacuated in two stages to this point in time, and thus a differential pressure stage is realized.

This procedure can be repeated by driving over further suction openings29at a lower pressure, e.g. the third suction opening29cshown inFIG. 5, until the pressure in the region between the plates11aand11bis lowered to the desired pressure level, e.g. that of the treatment chamber21.

Subsequently, the bottles enter the vacuum chamber21, are treated there (e.g. coated while plasma is generated) and then reach the lock channel17on the exit side. There, the pressure between the plates11aand11bis gradually increased again by driving over the ventilation openings31. This procedure is analogue to the above-described stepwise evacuation, however with opposite signs.

In contrast to the known revolving lock, the lock according to the disclosure does without any expensive components, such as a chamber rotor complicated to manufacture or the rotor housing. Instead, different differential pressure stages with essentially uniform or standardized components, such as e.g. the carrier plates11, can be realized and modified, if required, with the disclosure.