WO2003100117A1

WO2003100117A1 - Method and device for plasma treating workpieces

Info

Publication number: WO2003100117A1
Application number: PCT/DE2003/001503
Authority: WO
Inventors: Michael Litzenberg; Frank Lewin; Hartwig Müller; Klaus Vogel; Gregor Arnold; Stephan Behle; Andreas LÜTTRINGHAUS-HENKEL; Matthias Bicker; Jürgen Klein
Original assignee: Sig Technology Ltd.
Priority date: 2002-05-24
Filing date: 2003-05-09
Publication date: 2003-12-04
Also published as: AU2003233771A1

Abstract

Disclosed are a method and a device for plasma treating workpieces (5). Said workpiece is inserted into a chamber (17) of a treatment station (3), which can be at least partly evacuated, and is positioned within the treatment station by means of a holding element (46). The workpiece is impinged upon by at least two clamping elements (47, 48) of the holding element, which can be positioned relative to each other, in such a way that the workpiece is received by a clamping space (54) that is located between the clamping elements.

Description

Method and device for plasma treatment of

workpieces

The invention relates to a method for plasma treatment of workpieces, in which the workpiece is inserted into an at least partially evacuable plasma chamber of a treatment station and in which the workpiece is positioned within the treatment station by a holding element.

The invention further relates to a device for plasma treatment of workpieces, which has at least one evacuable plasma chamber for receiving the workpieces and in which the plasma chamber is arranged in the region of a treatment station, and in which the plasma chamber from a chamber floor, a chamber cover and a lateral one Chamber wall is limited and has at least one holding element for positioning the workpiece. Such methods and devices are used, for example, to provide plastics with surface coatings. In particular, such methods and devices are also already known for coating inner or outer surfaces of containers which are intended for packaging liquids. Devices for plasma sterilization are also known.

PCT-O 95/22413 describes a plasma chamber for internally coating PET bottles. The bottles to be coated are lifted into a plasma chamber by a movable base and connected to an adapter in the area of a bottle mouth. The bottle interior can be evacuated through the adapter. In addition, a hollow lance is inserted through the adapter into the interior of the bottles to supply process gas. The plasma is ignited using a microwave.

From this publication it is also known to arrange a plurality of plasma chambers on a rotating wheel. This supports a high production rate of bottles per unit of time.

In EP-OS 10 10 773 a feed device is explained in order to evacuate a bottle interior and to supply it with process gas. PCT-WO 01/31680 describes a plasma chamber into which the bottles are introduced from a movable lid which was previously connected to a mouth area of the bottles.

PCT-WO 00/58631 also already shows the arrangement of plasma stations on a rotating wheel and loading writes for such an arrangement a group assignment of vacuum pumps and plasma stations to support a favorable evacuation of the chambers and the interior of the bottles. In addition, the coating of several containers in a common plasma station or a common cavity is mentioned.

Another arrangement for carrying out an internal coating of bottles is described in PCT-WO 99/17334. In particular, an arrangement of a microwave generator above the plasma chamber and a vacuum and operating medium feed through a floor of the plasma chamber are described here.

In the vast majority of known methods, container layers made of silicon oxides with the general chemical formula SiO _x are used to improve the barrier properties of the thermoplastic material. Barrier layers of this type prevent oxygen from penetrating into the packaged liquids and escape of carbon dioxide in the case of liquids containing CO ₂ .

The previously known methods and devices are not yet sufficiently suitable to be used for mass production, in which both a low coating price per workpiece and a high production speed must be achieved.

The object of the present invention is therefore to provide a method of the type mentioned in the introduction in such a way that handling of the workpieces to be treated is supported at high speed and with great reliability. This object is achieved in that the workpiece is acted upon by at least two clamping elements of the holding element that can be positioned relative to one another such that the workpiece is received by a clamping space between the clamping elements.

Another object of the present invention is to construct a device of the type mentioned in the introduction in such a way that simple movement kinematics of the workpieces to be treated are supported.

According to the invention, this object is achieved in that the holding element has at least two clamping elements which can be positioned relative to one another and which are arranged relative to one another with a distance providing a clamping space for receiving the workpiece.

By fixing the workpieces between the positionable clamping elements of the holding element, it is possible to transport the workpieces to be treated at an essentially constant height level. This saves the time for a height positioning of the workpieces to be carried out in accordance with the prior art and the design effort required for this.

The procedural sequence for handling the workpieces is such that the plasma chamber is initially opened at least to the extent that the workpieces can be transferred to the holding element for inserting the workpieces into the plasma chamber. In particular, it is contemplated to carry out the transfer in such a way that the workpieces are transferred from a transfer element to the holding element, so that no independent movement drive for the holding element is required. After the workpieces have been positioned by the holding element within the plasma chamber, the sealing element is raised at a predeterminable point in time and thereby the interior of the workpiece is sealed relative to the interior of the plasma chamber.

Such sealing can take place both at the beginning of the evacuation process and after a part evacuation has already been carried out. A seal only after a partial evacuation has the advantage that an interior of the workpiece and the further interior of the plasma chamber can initially be evacuated together and that in a second evacuation step after sealing the interior of the workpiece, the negative pressure in the area of the interior of the workpiece is different Vacuum in the further interior of the plasma chamber can be specified. In particular, it is contemplated to specify the negative pressure in the interior of the workpiece lower than in the further interior of the plasma chamber.

After the machining process has been carried out and the ambient pressure within the plasma chamber and within the workpiece has been reached again, the workpiece is transferred from the holding element to a further transfer element. The transfer process is preferably carried out in such a way that the transfer element approaches the holding element, takes over the workpiece and then transports the workpiece away.

A favorable introduction of gravity is supported in that the positioning of the clamping elements is carried out in a horizontal direction. A simple implementation of transfer operations is supported in that the workpiece is positioned by pliers-like holding arms.

When coating hollow workpieces, which are arranged with their mouths facing downward, it proves to be advantageous that a cavity of the plasma station is evacuated through the chamber floor.

A simple implementation in terms of device technology is also supported in that process gas is supplied through the chamber floor.

A quick and uniform distribution of the process gas in an interior of the workpiece can be achieved in that the process gas is fed through an lance into an interior of the workpiece.

A simple opening and closing of the holding element is supported in that the workpiece is positioned by pivotably mounted holding arms.

In order to specify an automatic taking of a holder positioning, it is proposed that the holding arms of springs be pressed into a locking position.

Inserting the workpiece into the holding element is supported in that the holding arms are pressed apart when the workpiece is inserted into the clamping space.

To facilitate removal of the workpiece from the holding element, it is proposed that the holding arms be pulled apart when the workpiece is pulled out of the clamping space. be pressed. In particular, it is thought to cause the spreading apart by direct contact between the workpiece and the holding arms.

To avoid uncontrolled movement of the holding element in a closed state of the plasma chamber, it is proposed that locking elements for fixing the holding arms be positioned together with the chamber wall.

A very secure fixation of the workpiece can be achieved by arranging a stop element for fixing the workpiece at approximately the same height level as the holding arms.

To support controllable ignition of the plasma, it is proposed that microwaves generated by a microwave generator be introduced into the cavity in the area of the chamber cover.

A typical application is that a workpiece is treated from a thermoplastic.

In particular, it is contemplated that an interior of the workpiece is treated.

An extensive field of application is opened up by treating a container as a workpiece.

In particular, it is thought that a ₍ beverage bottle) is treated as the workpiece.

A high production rate with great reliability and high product quality can be achieved in that the at least one plasma station is transferred from a rotating plasma wheel from an input position to an output position.

An increase in production capacity with only a slightly increased expenditure on equipment can be achieved by providing several cavities from one plasma station.

For applications in the field of packaging for liquids, it proves particularly advantageous that the workpiece is fixed in a mouth area by the holding arms.

A typical application is defined in that a plasma coating is carried out as the plasma treatment.

In particular, it is contemplated that the plasma treatment is carried out using a low pressure plasma.

When coating plastic workpieces, it proves advantageous that plasma polymerization is carried out.

Good surface adhesion is supported by the fact that at least some organic substances are deposited by the plasma.

Particularly advantageous usage properties for workpieces for packaging food can be achieved in that at least some inorganic substances are deposited by the plasma. In the treatment of packaging, particular consideration is given to the fact that a plasma is used to deposit a substance to improve the barrier properties of the workpiece.

To support a high quality of use, it is proposed that an adhesion promoter is additionally deposited to improve the adhesion of the substance on a surface of the workpiece.

High productivity can be supported by treating at least two workpieces simultaneously in a common cavity.

Another area of application is that plasma sterilization is carried out as the plasma treatment.

It is also contemplated that a surface activation of the workpiece is carried out as a plasma treatment.

A resilient provision of the spring forces can take place in that the spring tensions are provided by leg springs. Alternatively, the spring forces can also be generated by compression springs.

To prevent an undesired change in the positioning of the workpiece within the plasma chamber, it is proposed that the holding arms be provided with locking webs in the area of their extension facing away from the fixing projections. A simple mechanical implementation can be achieved in that the locking webs of locking elements can be fixed.

To support permanent operability, also taking structural tolerances into account, it is proposed that the locking elements be made of a hardened material.

A further improvement in the positioning reliability of the workpiece can be brought about in that the holding element is provided with a stop element for the workpiece.

For plasma treatment of bottle-like workpieces, it proves to be particularly advantageous that the stop element and the fixing projections are arranged at a height level for loading a bottle-shaped workpiece between its support ring and its shoulder area.

Exemplary embodiments of the invention are shown schematically in the drawings. Show it:

Fig. 1 is a schematic diagram of a plurality of plasma chambers, which are arranged on a rotating plasma wheel and in which the plasma wheel is coupled to input and output wheels.

2 shows an arrangement similar to FIG. 1, in which the plasma station is each equipped with two plasma chambers, 3 is a perspective view of a plasma wheel with a plurality of plasma chambers,

4 is a perspective view of a plasma station with a cavity,

5 shows a front view of the device according to FIG. 4 with the plasma chamber closed,

6 shows a cross section along section line VI-VI in FIG. 5,

7 shows a representation corresponding to FIG. 5 with the plasma chamber open,

8 is a vertical section along section line VIII-VIII in Fig. 7,

9 is an enlarged view of the plasma chamber with the bottle to be coated according to FIG. 6,

10 is a further enlarged view of a connection element for holding the workpiece in the plasma chamber,

11 shows a schematic representation of a positioning of a bottle-shaped workpiece within the plasma chamber using a forceps-like holding element,

12 is a plan view of the holding element according to FIG. 11 without showing the workpiece, 13 is a perspective view of the holding element according to FIG. 12 and

14 shows a perspective illustration of the holding element according to FIG. 13 with inserted bottle-like workpiece and positioned locking elements.

1 shows a plasma module (1), which is provided with a rotating plasma wheel (2). A plurality of plasma stations (3) are arranged along a circumference of the plasma wheel (2). The plasma stations (3) are provided with cavities (4) or plasma chambers (17) for receiving workpieces (5) to be treated.

The workpieces to be treated (5) are the plasma module

(I) in the area of an input (6) and forwarded via a separating wheel (7) to a transfer wheel (8) which is equipped with positionable support arms (9). The support arms (9) are arranged pivotably relative to a base (10) of the transfer wheel (8), so that a change in the distance of the workpieces (5) can be carried out relative to one another. As a result, the workpieces (5) are transferred from the transfer wheel (8) to an input wheel

(II) with a spacing of the workpieces (5) relative to one another that is increased relative to the separating wheel (7). The input wheel (11) transfers the workpieces (5) to be treated to the plasma wheel (2). After the treatment has been carried out, the treated workpieces (5) are removed from an output wheel

(12) removed from the area of the plasma wheel (2) and transferred into the area of an output section (13).

In the embodiment according to FIG. 2, the plasma stations (3) each have two cavities (4) or plasma chambers (17). As a result, two workpieces (5) can be treated simultaneously. Basically, it is possible to make the cavities (4) completely separate from one another, but in principle it is also possible to delimit only partial areas from one another in a common cavity space such that an optimal coating of all workpieces (5) is ensured. In particular, it is contemplated here to separate the partial cavities from one another at least by means of separate microwave couplings.

Fig. 3 shows a perspective view of a plasma module (1) with a partially constructed plasma wheel (2). The plasma stations (3) are arranged on a support ring (14) which is designed as part of a rotary connection and is mounted in the area of a machine base (15). The plasma stations (3) each have a station frame (16) which holds plasma chambers (17). The plasma chambers (17) have cylindrical chamber walls (18) and microwave generators (19).

A rotary distributor (20) is arranged in a center of the plasma wheel (2), via which the plasma stations (3) are supplied with operating resources and energy. Ring lines (21) in particular can be used for the distribution of operating resources.

The workpieces (5) to be treated are shown below the cylindrical chamber walls (18). Lower parts of the plasma chambers (17) are not shown for the sake of simplicity.

Fig. 4 shows a plasma station (3) in perspective. It can be seen that the station frame (16) is provided with guide rods (23) on which a slide (24) for holding the cylindrical chamber wall (18) is guided. Fig. 4 shows the carriage (24) with the chamber wall (18) in a raised state, so that the workpiece (5) is released.

The microwave generator (19) is arranged in the upper region of the plasma station (3). The microwave generator (19) is connected via a deflection (25) and an adapter (26) to a coupling channel (27) which opens into the plasma chamber (17). Basically, the microwave generator (19) can be coupled both directly in the area of the chamber lid (31) and via a spacer element to the chamber lid (31) with a predeterminable distance to the chamber lid (31) and thus in a larger surrounding area of the chamber lid (31). to be ordered. The adapter (26) has the function of a transition element and the coupling channel (27) is designed as a coaxial conductor. A quartz glass window is arranged in the region of a junction of the coupling channel (27) in the chamber cover (31). The deflection (25) is designed as a waveguide.

The workpiece (5) is positioned in the area of a sealing element (28) which is arranged in the area of a chamber base (29). The chamber base (29) is designed as part of a chamber base (30). To facilitate adjustment, it is possible to fix the chamber base (30) in the area of the guide rods (23). Another variant is to attach the chamber base (30) directly to the station frame (16). With such an arrangement, it is also possible, for example, to design the guide rods (23) in two parts in the vertical direction. FIG. 5 shows a front view of the plasma station (3) according to FIG. 3 in a closed state of the plasma chamber (17). The carriage (24) with the cylindrical chamber wall (18) is lowered compared to the positioning in FIG. 4, so that the chamber wall (18) has moved against the chamber bottom (29). The plasma coating can be carried out in this positioning state.

FIG. 6 shows the arrangement according to FIG. 5 in a vertical sectional view. It can be seen in particular that the coupling channel (27) opens into a chamber cover (31) which has a laterally projecting flange (32). A seal (33) is arranged in the area of the flange (32) and is acted upon by an inner flange (34) of the chamber wall (18). In a lowered state of the chamber wall (18), the chamber wall (18) is thereby sealed relative to the chamber cover (31). Another seal (35) is arranged in a lower region of the chamber wall (18) in order to ensure a seal relative to the chamber bottom (29) here too.

In the positioning shown in FIG. 6, the chamber wall (18) encloses the cavity (4), so that both an interior of the cavity (4) and an interior of the workpiece (5) can be evacuated. To support a supply of process gas, a hollow lance (36) is arranged in the area of the chamber base (30) and can be moved into the interior of the workpiece (5). The lance (36) is positioned by a lance slide (37) which can be positioned along the guide rods (23). A process gas channel (38) runs inside the lance slide (37) and, in the raised position shown in FIG. 6, is coupled to a gas connection (39) of the chamber base (30) is. This arrangement avoids hose-like connecting elements on the lance slide (37).

FIGS. 7 and 8 show the arrangement according to FIGS. 5 and 6 in a raised state of the chamber wall (18). In this position of the chamber wall (18), it is possible to remove the treated workpiece (5) from the area of the plasma station (3) and to insert a new workpiece (5) to be treated. As an alternative to the positioning of the chamber wall (18) shown in the drawings in an open state of the plasma chamber (17) achieved by displacement upwards, it is also possible to carry out the opening process by displacing a structurally modified sleeve-shaped chamber wall in the vertical direction downwards.

In the exemplary embodiment shown, the coupling channel (27) has a cylindrical design and is arranged essentially coaxially with the chamber wall (18).

FIG. 9 shows the vertical section according to FIG. 6 in an enlarged partial illustration in the vicinity of the chamber wall (18). In particular, the overlap of the inner flange (34) of the chamber wall (18) over the flange (32) of the chamber cover (31) and the holding of the workpiece (5) by the holding element (28). In addition, it can be seen that the lance (36) is guided through a recess (40) in the holding element (28).

The positioning of the workpiece (5) in the area of the sealing element (28) can be seen in the enlarged illustration in FIG. 10. The sealing element (28) is inserted into a guide sleeve (41) which is provided with a spring chamber (42). In the spring chamber (42) is one Compression spring (43) used, which braces an outer flange (44) of the sealing element (28) relative to the guide sleeve (41).

In the positioning shown in FIG. 10, a thrust plate (45) mounted on the lance (36) is guided against the outer flange (44) and presses the sealing element (28) into its upper end position. In this positioning, an interior of the workpiece (5) is insulated from the interior of the cavity (4). In a lowered state of the lance (36), the compression spring (43) displaces the sealing element (28) relative to the guide sleeve (41) in such a way that a connection between the interior of the workpiece (5) and the interior of the cavity (4) is created.

Fig. 11 shows the positioning of the workpiece (5) within the plasma chamber (17) with the aid of a holding element (46). The holding element (46) is designed like pliers and has two pivotably mounted holding arms (47, 48). The holding arms (47, 48) are pivotable relative to axes of rotation (49, 50). To ensure automatic fixation of the workpiece (5) by the holding element (46), the holding arms (47, 48) of springs (51, 52) are pressed into a respective holding position. The use of leg springs (51, 52) is preferably considered.

The holding element (46) is arranged above the chamber base (30), so that after lifting the chamber wall (18) there is lateral accessibility of the holding element (46). The workpiece (5) can thereby be transferred from a positioning element to the holding element (46) without a lifting movement of the workpiece (5) in the direction of a longitudinal axis (53) of the cavity. FIG. 12 shows a top view of the holding element (46) according to FIG. 11 after removal of the workpiece (5). It can be seen in particular that a clamping space (54) for receiving the workpiece (5) is arranged between the holding arms (47, 48). The holding arms (47, 48) protrude into the clamping space (54) with fixing projections (55, 56). In addition, the holding arms (47, 48) have locking webs (57, 58) which face away from the fixing projections (55, 56) and which are arranged in one by locking elements (59, 60), which can preferably be positioned together with the chamber wall (18) Locking position can be fixed.

To further support and fix the workpiece (5), the holding element (46) has a stop element (61). The stop element (6) limits maximum insertion of the workpiece (5) into the clamping space (54). In the locking position, the workpiece (5) is pressed against the stop element (61) by the fixing projections (55, 56). The stop element (61) and the fixing projections (55, 56) are thereby arranged at approximately the same height level.

Fig. 12 additionally shows the sealing element (28) and the lance (36) at a lower level than the holding element (46) due to the selected viewing direction with respect to the plane of the drawing.

FIG. 13 shows the holding element (46) according to FIG. 12 in a perspective illustration and without depicting the locking elements (59, 60). It can be seen in particular that the holding element (46) has a base plate (62) from which the holding arms (47, 48) and the further components are carried. The base plate (62) can be elements (63, 64) and connecting elements (65, 66) in the area of the station frame (16). In particular, it is intended to be mounted on the chamber base (30).

Fig. 13 also shows that the fixing projections (55, 56) are each provided with insertion bevels (67) and outlet bevels (68). When the workpieces (5) are inserted into the clamping space (54), the workpiece (5) first comes into contact with the insertion bevels (67) and presses the holding arms (47, 48) apart against the forces of the springs (51, 52). After the workpiece (5) has been completely inserted into the clamping space (54), the holding arms (47, 48) automatically return to the locking position due to the forces of the springs (51, 52) and press the workpiece (5) against the stop element (61 ). The workpiece (5) is thereby fixed within the plasma chamber (17).

After completion of the treatment of the workpiece (5), the workpiece (5) is gripped by a transfer element and pulled against the outlet bevels (68). The outlet bevel (68) is preferably curved and is designed with a curvature course corresponding to an outer contour of the workpiece (5) in the contact area. The holding arms (47, 48) are thereby brought apart again and release the workpiece (5). In particular, it is contemplated to provide the transfer element with controlled tong arms. The controlled pliers arms enable the workpieces (5) to be gripped actively and support the application of compressive and tensile forces to the insertion bevels (67) and the outlet bevels (68). In particular, it is contemplated that the controlled pliers of the transfer elements at a substantially same height level to act as the holding arms (47, 48) or at a slightly lower or higher level on the workpiece (5). As a result, the introduction of tilting forces into the workpiece (5) is avoided or greatly reduced.

FIG. 14 shows the arrangement according to FIG. 13 after inserting a bottle-like workpiece (5) which is acted upon by the holding arms (47, 48) between a support ring (69) and a shoulder region (70). Holding such a bottle-like workpiece (5) in the neck region shown leads to a very stable fixation of the workpiece (5). The locking elements (59, 60) are also shown in FIG. 14. The locking elements (59, 60) are positioned together with the chamber wall (18). In the arrangement shown, the locking elements (59, 60) block a movement of the holding arms (47, 48), so that an uncontrolled opening of the holding element (46) is reliably prevented.

A typical treatment process is explained below using the example of a coating process and carried out in such a way that the workpiece (5) is first transported to the plasma wheel (2) using the input wheel (11) and that the sleeve-like chamber wall (18) is inserted in a pushed-up state of the workpiece (5) into the plasma station (3). To insert the workpiece (5), the workpiece (5) is first inserted into the clamping space (54) by a transfer element. After the workpiece (5) has been fixed by the holding arms (47, 48), the controlled holding pliers of the transfer element open and release the workpiece (5). After completion of the insertion process, the chamber wall (18) is lowered into its sealed position and initially simultaneously an evacuation of both the cavity (4) and an interior of the workpiece (5) is carried out.

After sufficient evacuation of the interior of the cavity (4), the lance (36) is moved into the interior of the workpiece (5) and the sealing of the interior of the workpiece (5) from the interior of the workpiece (5) is sealed off by a displacement of the sealing element (28). 4) performed. It is also possible to move the lance (36) into the workpiece (5) synchronously with the beginning of the evacuation of the interior of the cavity. The pressure inside the workpiece (5) is then further reduced. In addition, the positioning movement of the lance (36) is at least partially already carried out parallel to the positioning of the chamber wall (18). After reaching a sufficiently low vacuum, process gas is introduced into the interior of the workpiece (5) and the plasma is ignited with the aid of the microwave generator (19). In particular, it is intended to use the plasma to deposit both an adhesion promoter on an inner surface of the workpiece (5) and the actual barrier layer made of silicon oxides.

After the coating process has been completed, the lance (36) is removed from the interior of the workpiece (5) and the plasma chamber (17) and the interior of the workpiece (5) are ventilated. After reaching the ambient pressure within the cavity (4), the chamber wall (18) is raised again in order to remove the coated workpiece (5) and to enter a new workpiece (5) to be coated. In order to enable the workpiece (5) to be positioned laterally, the sealing element (28) is replaced at least in some areas move into the chamber base (3). To carry out the removal of the workpiece, a transfer element with a controlled pliers is again positioned in the area of the holding element (46) and the controlled pliers of the transfer element access the workpiece (5). The workpiece held in this way is then pulled out of the holding element (46), the holding arms (47, 48) being pressed apart against the forces of the springs (51, 52).

As an alternative to the interior coating of workpieces (5) explained above, exterior coatings, sterilizations or surface activations can also be carried out. In such embodiments, the holding element (46) in the case of bottle-like workpieces (5) grips the workpiece (5) preferably in the threaded area or at a short distance from the mouth opening.

The chamber wall (18), the sealing element (28) and / or the lance (36) can be positioned using different drive units. In principle, the use of pneumatic drives and / or electrical drives, in particular in one embodiment as a linear motor, is conceivable. In particular, however, it is envisaged to implement curve control to support exact movement coordination by rotating the plasma wheel (2). The curve control can be designed, for example, in such a way that control curves are arranged along a circumference of the plasma wheel (2), along which curve rollers are guided. The cam rollers are coupled to the components to be positioned.

Claims

Patent claims

1. A method for plasma treatment of workpieces, in which the workpiece is inserted into an at least partially evacuable chamber of a treatment station and in which the workpiece is positioned within the treatment station by a holding element, characterized in that the workpiece (5) by at least two relative to each other Positionable clamping elements of the holding element (46) are acted upon such that the workpiece (5) is received by a clamping space (54) between the clamping elements.

2. The method according to claim 1, characterized in that the positioning of the clamping elements is carried out in a horizontal direction.

3. The method according to claim 1 or 2, characterized in that the workpiece (5) of pliers-like holding arms (47, 48) is positioned.

4. The method according to any one of claims 1 to 3, characterized in that an evacuation of a cavity (4) of the plasma station (3) through the chamber bottom (29) takes place.

5. The method according to any one of claims 1 to 4, characterized in that process gas is supplied through the chamber bottom (29).

6. The method according to any one of claims 1 to 5, characterized in that the process gas is fed through a lance (36) into an interior of the workpiece (5).

7. The method according to any one of claims 1 to 6, characterized in that the workpiece (5) of pivotally mounted holding arms (47, 48) is positioned.

8. The method according to claim 7, characterized in that the holding arms (47, 48) of springs are pressed into a locking position.

9. The method according to any one of claims 1 to 8, characterized in that the holding arms (47, 48) are pressed apart when the workpiece (5) is inserted into the clamping space (54).

10. The method according to any one of claims 1 to 9, characterized in that the holding arms (47, 48) at a pulling the workpiece (5) out of the clamping space (54).

11. The method according to any one of claims 1 to 10, characterized in that locking elements (59, 60) for fixing the holding arms (47, 48) are positioned together with the chamber wall (18).

12. The method according to any one of claims 1 to 11, characterized in that a stop element (61) for fixing the workpiece (5) is arranged approximately at the same height level as the holding arms (47, 48).

13. The method according to any one of claims 1 to 12, characterized in that in the region of the chamber cover (31) from a microwave generator (19) microwaves are introduced into the cavity (4).

14. The method according to any one of claims 1 to 13, characterized in that a workpiece (5) is treated from a thermoplastic.

15. The method according to any one of claims 1 to 14, characterized in that an interior of a hollow workpiece (5) is treated.

16. The method according to any one of claims 1 to 15, characterized in that a container is treated as the workpiece (5).

17. The method according to any one of claims 1 to 16, characterized in that a beverage bottle is treated as the workpiece (5).

18. The method according to any one of claims 1 to 17, characterized in that the at least one plasma station (3) from a rotating plasma wheel (2) is transferred from an input position to an output position.

19. The method according to any one of claims 1 to 18, characterized in that a plurality of cavities (4) are provided by a plasma station (3).

20. The method according to any one of claims 1 to 19, characterized in that the workpiece (5) is fixed in a mouth region by the holding arms (47, 48).

21. The method according to any one of claims 1 to 20, characterized in that a plasma coating is carried out as the plasma treatment.

22. The method according to any one of claims 1 to 21, characterized in that the plasma treatment is carried out using a low-pressure plasma.

23. The method according to any one of claims 1 to 22, characterized in that a plasma polymerization is carried out,

24. The method according to any one of claims 1 to 23, characterized in that at least partially organic substances are deposited by the plasma.

25. The method according to any one of claims 1 to 23, characterized in that at least some inorganic substances are deposited by the plasma.

26. The method according to any one of claims 1 to 25, characterized in that a substance for improving the barrier properties of the workpiece (5) is deposited by the plasma.

27. The method according to claim 26, characterized in that in addition an adhesion promoter for improving an adherence of the substance is deposited on a surface of the workpiece (5).

28. The method according to any one of claims 1 to 27, characterized in that at least two workpieces (5) are treated simultaneously in a common cavity.

29. The method according to any one of claims 1 to 20, characterized in that a plasma sterilization is carried out as the plasma treatment.

30. The method according to any one of claims 1 to 20, characterized in that a surface activation of the workpiece (5) is carried out as a plasma treatment.

31.Device for the plasma treatment of workpieces, which has at least one evacuable plasma chamber for receiving the workpieces and in which the plasma chamber is arranged in the region of a treatment station, and in which the plasma chamber is delimited by a chamber bottom, a chamber cover and a lateral chamber wall and at least one Holding element for positioning the workpiece, characterized in that the holding element (46) has at least two clamping elements which can be positioned relative to one another and which are arranged relative to one another with a distance for receiving the workpiece (5) providing a clamping space (54).

32. Apparatus according to claim 31, characterized in that the clamping elements can be positioned in a horizontal direction.

33. Apparatus according to claim 31 or 32, characterized in that the clamping elements of pliers-like holding arms (47, 48) are provided.

34. Device according to one of claims 31 to 33, characterized in that for evacuating a cavity (4) of the plasma station (3) in the chamber bottom (29) at least one vacuum channel is arranged.

35. Device according to one of claims 31 to 34, characterized in that in the chamber bottom (29) at least one channel for supplying process gas is arranged.

36. Device according to one of claims 31 to 35, characterized in that for the supply of process gas in an interior of the workpiece (5) into a lance (36) is arranged positionable relative to the chamber bottom (29).

37. Device according to one of claims 31 to 36, characterized in that the holding arms (47, 48) are arranged pivotably relative to axes of rotation (49, 50).

38. Device according to one of claims 31 to 37, characterized in that the holding arms (47, 48) are provided with a spring tension in the direction of a locking position.

39. Apparatus according to claim 38, characterized in that the spring tension of leg springs (51, 52) are provided.

40. Device according to one of claims 31 to 39, characterized in that the holding arms (47, 48) have fixing projections (55, 56) which are each provided with an insertion bevel (67).

41. Device according to one of claims 31 to 39, characterized in that the holding arms (47, 48) have fixing projections (55, 56) which are each provided with an outlet bevel (68).

42. Device according to one of claims 31 to 41, characterized in that the holding arms (47, 48) are provided in the region of their extension facing away from the fixing projections (55, 56) with locking webs (57, 58).

43. Device according to one of claims 31 to 42, characterized in that a microwave generator (19) is arranged in the region of the chamber cover (31).

44. Device according to one of claims 31 to 43, characterized in that the plasma station (3) for coating a workpiece (5) is made of a thermoplastic material.

45. Device according to one of claims 31 to 44, characterized in that the plasma station (3) is designed for coating a container-like workpiece (5).

46. Device according to one of claims 31 to 45, characterized in that the plasma station (3) for coating an interior of a hollow workpiece (5) is formed.

47. Device according to one of claims 31 to 46, characterized in that the plasma station (3) for coating a workpiece (5) is designed in the form of a beverage bottle.

48. Device according to one of claims 31 to 47, characterized in that the at least one plasma station (3) is carried by a rotating plasma wheel (2).

49. Device according to one of claims 31 to 48, characterized in that a plurality of cavities (4) are arranged in the region of the plasma station (3).

50. Device according to one of claims 31 to 49, characterized in that one for providing at least two cavities (4) provided chamber wall (18) is arranged positionable.

51. Device according to one of claims 31 to 50, characterized in that the locking webs (57, 58) of locking elements (59, 60) can be fixed.

52. Apparatus according to claim 51, characterized in that the locking elements (59, 60) are formed from a hardened material.

53. Apparatus according to claim 51 or 52, characterized in that the locking elements (59, 60) from the chamber wall (18) can be positioned.

54. Device according to one of claims 31 to 53, characterized in that the holding element (46) is provided with a stop element (61) for the workpiece (5).

55. Device according to one of claims 31 to 54, characterized in that the fixing projections (55, 56) and the stop element (61) are arranged at approximately the same height level.

56. Device according to one of claims 31 to 55, characterized in that the stop element (61) and the fixing projections (55, 56) are arranged on a height level to act on a mouth region of a bottle-shaped workpiece (5).

57. Device according to one of claims 31 to 56, characterized in that the stop element (61) and the fixing projections (55, 56) at a height for loading a bottle-shaped workpiece (5) between the support ring (69) and the shoulder area (70 ) are arranged.