WO2020126543A1

WO2020126543A1 - Device and method for treating a workpiece surface using an atmospheric plasma beam

Info

Publication number: WO2020126543A1
Application number: PCT/EP2019/083963
Authority: WO
Inventors: Syed Salman ASAD; Christian Buske; Matthias HERLTH
Original assignee: Plasmatreat Gmbh
Priority date: 2018-12-19
Filing date: 2019-12-06
Publication date: 2020-06-25
Also published as: DE102018132960A1

Abstract

The invention relates to a device (2, 2', 2", 2"', 3) for treating a workpiece surface (18), comprising a plasma nozzle (4, 4', 4", 4'") which is designed to generate an atmospheric plasma beam (6), said plasma nozzle (4, 4', 4", 4'") having a nozzle opening (8) from which an atmospheric plasma beam (6) exits during operation. A deflecting element (10, 10', 10", 10"', 11) with a convexly curved contact surface (12) is positioned in the region of the nozzle opening (8) such that the plasma beam (6) interacts with the contact surface (12) of the deflecting element (10, 10', 10", 10"', 11) when the plasma nozzle (4, 4', 4", 4"') is being operated, in particular the plasma beam strikes the contact surface. The invention additionally relates to a method for treating a workpiece surface (18) using such a device (2, 2', 2", 2"', 3).

Description

Device and method for treating a workpiece surface with an atmospheric plasma jet

The present invention relates to a device for treating a

Workpiece surface, with a plasma nozzle, which is used to generate a

atmospheric plasma jet is set up, the plasma nozzle

Has nozzle opening from which an atmospheric plasma jet emerges during operation. The invention further relates to a method for treating a

Workpiece surface with such a device.

Various nozzle arrangements are known from the prior art, through which a plasma jet generated in the plasma nozzle can be guided in order to influence its direction, shape or spatial distribution. For example, EP 1 236 380 A1 discloses a nozzle arrangement with which the plasma jet is widely fanned out. Furthermore, DE 10 2016 125 699 discloses a nozzle arrangement with which the plasma jet can be divided into a plurality of partial jets, with which a larger area of a surface can be applied. Such nozzle arrangements can be formed in one piece with the plasma nozzle or as an attachment for a plasma nozzle, the attachment emerging from the plasma nozzle being introduced directly into the nozzle arrangement.

Furthermore, from EP 1 067 829 A1 and DE 10 2015 121 252 A1, for example, nozzle arrangements are angled with respect to the plasma nozzle axis

Nozzle opening is known, so that the plasma jet emerges obliquely from the plasma nozzle. By rotating the plasma nozzle, a larger area of the surface to be treated can be applied. If such a rotating plasma nozzle is moved along a workpiece surface, a relatively wide one can be used in this way

Treatment track are generated. However, with this type of treatment, there are differences in the intensity of the plasma treatment Workpiece surface This effect is described in detail in DE 10 2015 121 252 A1. In order to counteract this effect, it is proposed in DE 10 2015 121 252 A1 to additionally provide a shield surrounding the nozzle arrangement which interacts with the plasma jet and makes it more uniform.

As the examples described above show, previous measures for influencing the shape, direction or distribution of the plasma jet are essentially based on suitably shaping and aligning the channel or the nozzle opening leading to the nozzle opening. This has the disadvantage that the nozzle arrangements can be designed to be structurally complex, depending on the planned influencing, the type or the degree of influencing cannot be changed or can only be changed in a complex manner, and the plasma jet can generate quite a lot of energy due to prolonged contact with walls of the nozzle arrangement loses.

Against this background, the technical problem underlying the following invention is to provide an alternative possibility for influencing the shape, direction and / or distribution of the plasma beam, which reduces the problems described above as possible.

This object is achieved according to the invention in a device for treating a workpiece surface with a plasma nozzle which is set up to generate an atmospheric plasma jet, the plasma nozzle having a nozzle opening from which an atmospheric plasma jet emerges during operation, in that in the region of the nozzle opening Deflector with a convexly curved

Contact surface is positioned such that the plasma jet during operation of the

Plasma nozzle interacts with the contact surface of the deflecting element, in particular grazes it.

It was found that the shape, the direction and / or the spatial distribution of the atmospheric emerging from the plasma nozzle during operation

Plasma jets can be influenced by the plasma jet with a convex curved contact surface of a deflecting element is brought into interaction. Depending on the curvature of the contact surface, a deflection of the

Plasma beams observed in a direction away from the contact surface or towards the contact surface. In this way, in particular the original beam direction of the plasma beam can be changed.

In order for this interaction to occur, part of the convexly curved contact surface of the deflecting element projects into the plasma jet emerging from the nozzle opening during operation. The knowledge on which the invention is based is, in particular, that convexly curved contact surfaces deflect a plasma beam. Therefore, the device described can be used to spatially model the plasma jet during or after it flows out of the nozzle opening or to influence its direction, which makes it possible, for example, to achieve a desired intensity distribution of the plasma jet on a surface.

The use of a deflection element has various advantages over influencing or changing the direction of the plasma jet by means of a curved nozzle channel.

In contrast to a curved nozzle channel, a deflection element with a convexly curved contact surface is typically structurally simpler to manufacture and can be arranged more flexibly in order to achieve the desired deflection of the plasma jet. Furthermore, such a deflection element enables a more compact construction of the plasma nozzle. As a result, the device can be better used to treat areas of a workpiece surface that are difficult to access, for example niches or areas under overhangs, with a plasma jet.

Another advantage is that the plasma jet only has a short distance and preferably only at the edge with respect to its cross-section with the convex curved contact surface of the deflecting element interacts, in particular it only grazes. This results in significantly less energy loss of the plasma beam than, for example, a plasma beam deflection through a channel or a

Reflector element, for example in the form of a shield. Therefore, at

A more intensive surface treatment can be achieved using the above-mentioned device with the same plasma power.

The deflection element can be permanently connected to the plasma nozzle,

for example glued. Alternatively, the deflection element can also be removably attached to the plasma nozzle, which enables the deflection element to be exchanged and / or aligned.

The deflection element can be positioned such that it continuously interacts with a plasma jet emerging from the nozzle opening. Alternatively, the deflection element can also be positioned in such a way that it interacts temporarily with the plasma jet, in particular if the nozzle opening moves relative to the deflection element. For example, it is conceivable that the nozzle opening rotates and that

Deflection element is positioned such that the plasma jet emerging from the nozzle opening only deflects the deflection element at certain positions

Nozzle opening grazes. In this way, the plasma jet can be influenced depending on the position of the nozzle opening.

The above object is further achieved according to the invention by a

Method for treating a workpiece surface with the device described above, in which an atmospheric plasma jet is generated with the plasma nozzle and emerges from the nozzle opening of the plasma nozzle, the plasma jet interacting with, in particular grazing, the contact surface of the deflecting element, and using the plasma jet the workpiece surface to be treated is straightened.

Through the above procedure, the treatment of the

The plasma beam used can be influenced in a targeted manner, for example, be made more even. On the basis of the described modeling ability of the plasma jet, in particular its spatial distribution and thus its intensity, it can also be achieved to direct the plasma jet precisely onto certain areas of a workpiece surface or the

Homogenize plasma treatment of the workpiece surface.

Within the scope of this description, a treatment of a

Workpiece surface with a plasma jet in particular one

Understanding surface pretreatment, by means of which the surface tension is changed and better wettability of the workpiece surface with fluids is achieved. A treatment of the workpiece surface is furthermore also understood to mean a surface coating, in particular in that a surface coating is achieved by adding at least one precursor to the plasma jet by means of a chemical reaction taking place in the plasma jet and / or on the workpiece surface, at least some of the chemical products

is deposited. Treatment of a workpiece surface also includes cleaning, disinfection or sterilization of the

Workpiece surface understood.

Various embodiments of the device and of the method are described below, the individual embodiments applying to the device and the method independently of one another. In addition, the embodiments can be combined with one another.

In one embodiment, the deflection element consists of an electrically insulating material, in particular glass or ceramic. It has been found that the energy loss of the plasma beam can be reduced in this way through the interaction with the deflection element. In addition, glass or ceramic, in particular, have good robustness or inertness with regard to the influence of a plasma jet. Glass or ceramics are also heat-resistant. The

Deflection element can be made entirely of an electrically insulating material such as Example, glass or ceramic, or alternatively be coated with such a material.

In a further embodiment, the deflection element is rod-shaped, in particular in the form of a cylinder or polygonal rod. The deflection element can have, for example, the shape of a cylinder, tube, square rod, hexagonal rod or another rod shape in which a convexly curved contact surface is provided. In the case of a cylindrical or tubular rod, the entire

Outer surface is convexly curved, so that each section of the outer surface as

Contact surface can be used. In the case of a polygonal rod, one edge forms a convexly curved contact surface, typically with a very small one

Radius of curvature. Both solid and hollow bars are conceivable, whereby hollow bars can be cooled more easily, for example, by the inside of one

Coolant can be flowed through.

In a further embodiment, the deflection element extends transversely to the direction of the nozzle opening. The direction of the nozzle opening is understood to mean the direction of the last section of the inner channel of the plasma nozzle to the nozzle opening, which specifies the direction of the plasma jet emerging from the nozzle opening if it were not influenced by the deflection element. In the embodiment mentioned above, the deflection element extends transversely to this direction. In this way, a strong deflection of the plasma beam could be achieved.

In a further embodiment, the deflection element is designed to be adjustable in order to change the positioning of the deflection element in relation to the nozzle opening. In this way, the deflection element can influence the plasma beam

be adjusted as required. In particular, the size of the convexly curved contact surface of the deflection element, which interacts with the plasma beam during operation, can be influenced in this way. The size of the in use with the

Plasma jet interacting contact area significantly influences the type and intensity of the deflection of the plasma jet. In particular the deflection angle, ie the Angle between the direction of the nozzle opening and the deflected plasma jet depends on the position of the deflecting element relative to the nozzle opening.

In a further embodiment, the contact surface has a radius of curvature of at most 2 mm. It has been found that a plasma jet at

Interaction with a convexly curved contact surface with a

Radius of curvature of at most 2 mm is bent away from the contact surface. A contact surface with a radius of curvature of at most 2 mm can be achieved, for example, by using a cylindrical deflection element with a diameter of at most 4 mm (i.e. with a radius of at most 2 mm).

In a further embodiment, the contact surface has a radius of curvature of more than 2 mm. It has been found that a plasma jet at

Interaction with a convexly curved contact surface with a

Radius of curvature of more than 2 mm is bent towards the contact surface. A contact surface with a radius of curvature of more than 2 mm can be achieved, for example, by using a cylindrical deflection element with a diameter of at most 4 mm (i.e. with a radius of more than 2 mm).

With the basis of the two previous embodiments

Knowledge is possible with the described device to steer a plasma beam in the desired directions depending on the radius of curvature of the contact surface of a deflecting element. This can be used for a variety of applications and possibilities.

In a further embodiment, a further deflection element with a convexly curved contact surface is positioned in the region of the nozzle opening in such a way that the plasma jet interacts with the contact surface of the further deflection element during operation of the plasma nozzle, in particular grazes it. By using several deflection elements, the plasma beam can be influenced from different sides, thereby influencing the direction and / or in a more targeted manner the shape of the plasma jet or the treatment effected on the surface can be achieved. The contact surface of the deflecting element and the further deflecting element can have the same radius of curvature or different ones

Have radii of curvature. Furthermore, more than two deflection elements are also conceivable.

In a further embodiment, the deflecting element and the other

Deflector positioned on opposite sides of the nozzle opening. The plasma jet then emerges between the two deflection elements during operation. In this way, the plasma beam can be influenced on two opposite sides. This is advantageous, for example, if the device is moved relative to a workpiece surface to be treated. By appropriately aligning the direction of movement and the course of the deflection elements, an influencing of the plasma beam by the deflection elements can thus either

Direction of movement or across it can be achieved.

When using deflection elements that bend the plasma jet in the direction of their respective contact surfaces, the plasma jet can be expanded in one plane. When using deflection elements that bend the plasma beam away from their respective contact surfaces, the plasma beam can be focused in one plane. The deflection element and the further deflection element can, for example, be aligned parallel to one another.

In a further embodiment, the deflecting element and the other

Deflection element positioned at the nozzle opening such that the

The direction of extension of the deflecting element and the direction of extension of the further deflecting element run at an angle to one another, preferably at a right angle. This arrangement of the deflection elements makes it possible to further influence the plasma beam. For example, if the device is moved relative to a workpiece surface to be treated, this can be done, for example an influence on the plasma beam by the deflection elements both in

Direction of movement as well as transverse to it can be achieved.

In a further embodiment, the contact surface of the deflection element and the contact surface of the further deflection element have different curvatures. As previously described, different curvatures of contact surfaces cause different deflections of a plasma beam

Interaction of the plasma jet with the respective contact surfaces. The plasma beam can be flexibly influenced by using deflection elements with contact surfaces of different curvature. For example, the

Plasma beam can be expanded in one level and focused in another level.

In a further embodiment, the plasma nozzle has a nozzle head which rotates around an axis of rotation during operation, the nozzle head having the nozzle opening. In this way, the plasma jet can be distributed over a larger area. The one or more deflection elements can be positioned in such a way that their contact surfaces interact continuously or temporarily with the plasma jet. The plasma nozzle can, for example, be set up so that the nozzle head rotates during operation at a rotational speed in the range from 1000 to 5600 revolutions per minute. The use of high

Rotation speeds result in a more homogeneous distribution of the plasma jet on a surface, for example a workpiece surface.

In a further embodiment of the device with a rotating nozzle head, the direction of the nozzle opening runs at an angle to the axis of rotation, and the deflection element is positioned such that the plasma jet at least temporarily when the nozzle head is rotated fully about the axis of rotation,

preferably only intermittently interacts with the contact surface of the deflecting element. Since the direction of the nozzle opening is at an angle to

The axis of rotation runs, the plasma jet emerges at this angle during operation the nozzle opening. In combination with a rotation of the nozzle head around the axis of rotation, this leads to a plasma jet which, depending on the current one

Rotation position of the nozzle head emerges in different spatial directions.

In addition, a deflecting element with a convexly curved contact surface is positioned in the region of the nozzle opening in such a way that the plasma jet interacts at least temporarily with the contact surface of the deflecting element when the nozzle head rotates fully around the axis of rotation. Based on these

Interaction, the plasma beam is deflected at least temporarily, the direction of deflection being dependent on the radius of curvature of the contact surface, as described above. In this way, the plasma jet can be dependent on the

Affect the rotational position of the nozzle head. This makes it possible, for example, to even out the plasma treatment of a surface by reducing the intensity of the plasma occurring in a rotating plasma nozzle head in the center of the circular plasma track by correspondingly deflecting the

Plasma jet is balanced.

In particular, the deflection element can be positioned such that the plasma jet emerging from the rotating plasma nozzle only then coincides with the

Contact surface of the deflection element interacts when the plasma jet is directed in the corresponding spatial direction of the deflection element.

In a further embodiment, the nozzle opening of the nozzle head is arranged eccentrically to the axis of rotation. In this way, the

Treatment trace of the plasma jet on the surface to be treated can be further enlarged.

In a further embodiment, the deflection element is positioned in a rotationally fixed manner on the nozzle head. In the case of a rotationally fixed positioning of the deflection element on the nozzle head, there is a continuous, ie constant, deflection of the plasma beam upon interaction between the contact surface of the deflection element and the plasma jet. There the deflecting element also rotates when the nozzle head rotates, the direction in which the plasma jet is deflected by the deflecting element also rotates. In this way, the same effect can be achieved as with a nozzle opening running at an angle to the axis of rotation. In contrast, the use of the deflection element has the advantage that the contact of the plasma beam with the

Channel wall of the plasma nozzle and thus the energy loss is reduced.

In particular, the angular direction of the plasma jet can be achieved with a nozzle opening running in the direction of the plasma nozzle. Furthermore, the

Use of the deflecting element has the advantage that the nozzle head can be made more compact than with a nozzle opening running at an angle to the axis of rotation, so that areas of a workpiece that are difficult to access can be better reached with the nozzle head.

The rotationally fixed positioning of the deflecting element is preferably adjustable in such a way that the contact surface can be positioned further to or away from the nozzle opening. In this way, the deflection angle can be adjusted as required. Additionally or alternatively, the rotationally fixed positioning of the deflection element is preferably adjustable in such a way that the angle of the convex contact surface to the nozzle opening can be adjusted. In this way, the deflection angle can also be influenced.

In one embodiment of the method, the plasma nozzle and the

Workpiece surface moved in a direction of movement relative to each other and the deflecting element is on the side of the nozzle opening in or against the

Positioned in the direction of movement. In this way, the plasma beam can be influenced in the plane of the direction of movement, for example expanded, focused or evened out.

When treating a workpiece surface, a flat part of the workpiece surface is usually treated. For this purpose, the one to be treated

The workpiece surface is usually scanned in paths with the plasma jet. This happens either by a process of the plasma nozzle, by a process of the workpiece or by a combined process of the plasma nozzle and workpiece. The direction of the relative movement resulting from this method is referred to below as the direction of movement.

When treating workpiece surfaces with a plasma jet, the intensity profile of a plasma jet across its cross section can result in differences in the intensity of the plasma treatment on the workpiece surface, in particular transverse to the direction of movement. In plasma treatments with rotating nozzle heads, differences in the intensity of the plasma treatment can occur, particularly both in and across the direction of movement. The superimposition of the rotation of the nozzle head and the movement between the plasma nozzle and the workpiece surface results in a spiral trajectory of the plasma jet on the workpiece surface in the treatment track. This leads to an increase in treatment intensity, particularly at the edges of the treatment track (i.e. across the treatment direction). Continue to occur within the

Treatment track intensity minima between the individual spirals of the trajectory. These effects lead to inhomogeneities of the plasma treatment on the

Workpiece surface.

In order to achieve an improved homogeneity of the plasma treatment on the workpiece surface, it has proven to be particularly advantageous

To position the deflection element on the side of the nozzle opening in the direction of movement and / or a deflection element on the side of the nozzle opening in the opposite direction of movement. In this way, the plasma jet can be in the plane of the

Direction of movement can be influenced so that a more homogeneous treatment is achieved. In particular, the plasma jet in the plane of the

Movement direction are expanded so that pronounced intensity minima between the individual spirals of the trajectory is counteracted. For this purpose, the radius of curvature of the contact surfaces is preferably dimensioned such that the plasma beam is bent toward the respective deflection element. In particular the radius of curvature of the contact surface of such a deflection element is at most 2 mm.

To achieve an improved homogeneity of the plasma treatment on the workpiece surface, it has also proven to be particularly advantageous to position a deflection element on one or two sides of the nozzle opening transversely to the direction of movement. In this way, the plasma jet in the plane transverse to the direction of movement can be influenced so that a more homogeneous treatment is achieved. In particular, the plasma jet in the plane transverse to

Direction of movement to the center of the treatment track are deflected so that intensity maxima at the edge of the treatment track can be reduced. For this purpose, the radius of curvature of the contact surfaces is preferably dimensioned such that the plasma beam is bent away from the respective deflection element. In this way, the plasma beam is bent towards the center at the edges of the treatment track, so that the intensity maxima at the edge are reduced.

In particular, the radius of curvature of the contact surface is such

Deflection elements more than 2 mm.

In a further embodiment of the method, the two last-described embodiments are combined. For this purpose

preferably two deflection elements are positioned on the side of the nozzle opening in and against the direction of movement and two further deflection elements are positioned on the sides of the nozzle opening transversely to the direction of movement. The

Radii of curvature of the contact surfaces of the deflection elements on the sides in and against the direction of movement are preferably greater than the radii of curvature of the contact surfaces of the deflection elements on the sides transverse to the direction of movement.

Other features and advantages of the device and the method for

Treatment of a workpiece surface with such a device result from the following description of exemplary embodiments, reference being made to the attached drawing. Show in the drawing

Fig. La-b a first embodiment of the device for treating a

Workpiece surface,

2a-b a second embodiment of the device for treating a

Workpiece surface,

3a-c another embodiment of the device and a

Embodiment of the method for treating a workpiece surface,

Fig. 4a-c another embodiment of the device and a

Embodiment of the method for treating a workpiece surface,

Fig. 5a-c representation of the treatment track and intensity profiles with rotating

Nozzle head,

6 test results of contact angle measurements,

Fig. 7 is a plasma nozzle with angled nozzle opening and

Fig. 8 shows another embodiment of the device for treating a

Workpiece surface.

In the following description of various exemplary embodiments, components that correspond to one another are partially provided with the same reference numerals, even if the components in the various exemplary embodiments can have differences in their dimensions or shape. FIGS. 1 a and 1 b show a first exemplary embodiment of the device 2 with a plasma nozzle 4, which is set up for generating an atmospheric plasma jet 6. The plasma nozzle 4 has a nozzle opening 8 from which the

Plasma jet 6 emerges. A deflection element 10 with a convexly curved contact surface 12 is adjustably mounted in the region of the nozzle opening 8. For example, the deflection element 10 can be connected to the plasma nozzle directly or via a holding element (not shown). In the present example, the deflection element 10 is designed in the form of a cylindrical rod. The convexly curved contact surface 12 is correspondingly formed by the surface of the rod 10. The

The direction of extension of the deflecting element 10 extends into the plane of the paper and the material of the deflecting element consists of an electrically insulating material, in particular glass or ceramic. In the present example, the deflection element has a radius of curvature of at most 2 mm.

In the comparison between Fig. La and lb is the effect of the distraction by

Interaction of plasma beam 6 and contact surface 12 can be seen in FIG. 1 a, the deflection element 10 is arranged laterally offset from the plasma beam 6, so that the contact surface 12 and the plasma beam 6 do not interact with one another. The plasma jet 6 leaves the nozzle opening 8 in the direction of the nozzle opening 8. In FIG. 1b, the deflection element 10 is positioned displaced to the left, so that the plasma jet 6 grazes the contact surface 12. It was found that deflection away from the deflection element 10 takes place when the convexly curved contact surface 12 of the deflection element 10 has a radius of curvature of at most 2 mm.

A similar effect could be achieved if instead of the cylindrical one

Deflection element 10 the edge of a polygonal rod analogous to Fig. Lb with the

Plasma beam 6 is brought into interaction. The edge of the polygonal bar corresponds to a contact surface 12 with a very small radius of curvature of at most 2 mm.

2a to 2b show a second exemplary embodiment of a device 2 'according to the invention, a deflection element 10 "having a larger radius of curvature of the convexly curved contact surface 12 being used compared to FIGS. 1a to 1b. The radius of curvature is now more than 2 mm. 2a offers a similar image to FIG. La, since there is no interaction between the plasma jet 6 and the contact surface 12.

2b shows how the plasma jet 6 interacts with the contact surface 12, the contact surface 12 having a radius of curvature of more than 2 mm. It was found that in this case the plasma beam 6 lies around the deflection element 10 ", i.e. there is a deflection of the plasma beam 6 in the direction of the

Deflection elements 10 "instead.

In this way, the plasma jet 6 can be positioned by positioning a suitable deflection element with a convexly curved contact surface in the region of the

Influence the nozzle opening 8 in the desired manner, in particular deflect it.

3a to 3c show a further exemplary embodiment of a device 2 "and an exemplary embodiment of the method for treating a workpiece surface 18 with the device 2". The plasma nozzle 4 ′ (only shown in sections) of the device 2 ″ has a nozzle head 16 rotating during operation about an axis of rotation 14, the nozzle head 16 having the nozzle opening 8

Nozzle opening 8 extends at an angle to the axis of rotation 14, so that the plasma jet exits the nozzle opening 8 obliquely with respect to the axis of rotation 14.

Furthermore, the device has a deflection element 10 and a further deflection element 10 ', the two deflection elements 10, 10' each being convexly curved Have contact surfaces 12 whose radius of curvature is at most 2 mm. During operation - depending on the rotational position of the nozzle head 16 - one of the contact surfaces 12 of the deflecting elements 10, 10 'interacts with the plasma jet 6 at times. There is also a relative movement between the device 2 "and a workpiece surface 18 to be treated. The direction of the

Relative movement (direction of movement) is represented by arrow 20. The

Extending directions of the deflection elements 10, 10 'are parallel to

Direction of movement arranged.

3a shows a first snapshot of the method in which the

The rotational position of the nozzle head 16 is such that the plasma jet 6 interacts with the contact surface 12 of the further deflecting element 10 'and is deflected by the latter. The deflection takes place away from the deflection element into the center of the circle described by the rotation about the axis of rotation 14.

3b shows a second snapshot of the method in which the

The rotational position of the nozzle head 16 is such that the plasma jet 6 does not interact with any of the deflection elements 10, 10 '. The plasma jet 6 emerging obliquely from the nozzle head strikes without being deflected by deflection elements

Workpiece surface 18.

3c shows a third snapshot of the method in which the

The rotational position of the nozzle head 16 is such that the plasma jet 6 interacts with that of the contact surface 12 of the deflecting element 10 and is deflected by the latter. The deflection again takes place away from the deflection element into the center of the circle described by the rotation about the axis of rotation 14.

The deflection elements 10 and 10 ′ of the device 2 ″ shown in FIGS. 3a-c thus direct the plasma beam 6 into the center at the edges of the treatment track on the workpiece surface 18 the intensity maximum occurring on the treatment track is reduced and the

Surface treatment can be homogenized.

4a-c show a further exemplary embodiment of a device and a further exemplary embodiment of the method for treating a

Workpiece surface 18 with the device 2. The device 2 ″ ”has a structure like the device 2 ″ from FIGS. 3a-c, but using deflection elements 10 ″ and 10 ″ ′ whose convexly curved contact surfaces 12 have larger radii of curvature. The radii of curvature of the deflection elements 10 "and 10" 'are more than 2 mm. Furthermore, the deflection elements 10 ″, 10 ′ ″ are aligned transversely to the direction of movement 20.

4a shows a first snapshot of the method in which the

The rotational position of the nozzle head 16 is such that the plasma jet 6 interacts with and is deflected by the contact surface 12 of the further deflecting element 10 ″. The deflection takes place in the direction of the deflecting element, out of the center of the circle described by the rotation about the axis of rotation 14 .

4b further shows a second snapshot of the method in which the rotational position of the nozzle head 16 is such that the plasma jet 6 does not interact with any of the deflection elements 10 ", 10 '". The plasma jet 6 emerging obliquely from the nozzle head 16 strikes the workpiece surface 18 without being deflected by deflection elements.

4c shows a third snapshot of the method in which the

The rotational position of the nozzle head 16 is such that the plasma jet 6 interacts with the contact surface 12 of the deflecting element 10 ″ and is deflected by the latter. The plasma beam 6 is thus deflected out of the center in the plane of the direction of movement 20 and thereby widened by the deflection elements 10 "and 10"'of the device 2'"shown in FIGS. 4a-c. In this way, it is possible

Intensity minima in the areas between those of the plasma beam in the

Traces of treatment traversed by spirals on the workpiece surface 18

balanced or prevented and the surface treatment are homogenized.

Another exemplary embodiment, not shown, is achieved by combining the devices 2 "from FIGS. 3a-c and 2" from FIGS. 4a-c. Such a device has two deflection elements 10, 10 'with contact surfaces with a smaller one

Radius of curvature on the sides of the nozzle opening transverse to the direction of movement 20 and two further deflection elements 10 ", 10 '" with contact surfaces with a larger one

Radius of curvature on the sides of the nozzle opening 8 in and against the

Direction of movement 20 on. In this way, homogenization of the

Plasma treatment can be achieved transversely and in the direction of movement.

5a schematically shows the spiral trajectory of the plasma jet 6 on the workpiece surface 18, which is characterized by the superimposition of the rotation of the

Nozzle head 16 and the relative movement 20 (in FIG. 5a in the y direction) between device 2 "or 2 '" and workpiece surface 18. The trajectory (line) represents the point of impact of the maximum plasma intensity. The spiral trajectory results in a relatively wide treatment track on the

Workpiece surface 18. The direction of movement (y) leads to the effect that the outer areas of the treatment track in the area of the dashed lines are treated more intensively with the plasma than is the case for the central areas of the treatment track.

This leads to the intensity distribution shown in FIG. 5b, which have two maxima which occur in the outer regions of the treatment track, indicated by the dashed lines. In between there is only one noticeable lower intensity of the plasma treatment, so that an intensity minimum arises in the middle of the treatment lane.

In a device 2 "according to FIGS. 3a-c, the rotating plasma jet 6 is deflected inwards by the deflecting elements 10, 10 'at the edges of the treatment track, so that a more uniform plasma treatment along the

Treatment track is reached. This is represented in FIG. 5c by the intensity profile which, in contrast to FIG. 5b, assumes a flat or only slightly wavy shape of a plateau. If treatment traces lying next to one another are then brought overlapping onto the workpiece surface 18 in such a way that the

Summed up overlap areas, the intensity of the plateau is reached, then the workpiece surface 18 is treated more uniformly by the plasma jet 6 than was previously possible in the prior art. In the present case, this can in particular also be provided by providing those shown in FIGS. 4a-c

Deflection elements 10 ″, 10 ″ ′ can be achieved, which widen the plasma jet or its trace on the workpiece surface during one revolution of the nozzle head 16.

In order to investigate the homogenization of the plasma treatment when using a device with deflection elements 10, 10 'from FIG. 3 and deflection elements 10 ", 10'" from FIG. 4, tests with contact angle measurements were carried out. Such contact angle measurements allow a statement about the strength and the

Homogeneity of the plasma treatment. When measuring the contact angle

(Water) drops placed on the treated workpiece surface 18 and the contact angle of the drop to the workpiece surface 18 measured. The smaller the measured contact angle, the stronger the plasma treatment at the drop location.

The apparatus 2 "shown in FIGS. 3a-c was used for the experiments, which in addition to the deflection elements 10 and 10 '(transverse to the direction of movement) also the deflection elements 10" and 10' "shown in FIGS. 4a-c (in / contrary to

Direction of movement). This device was then used to treat the surface of a first PE sample along a treatment track. Furthermore, the surface of a second PE sample was treated along a treatment track, the deflection elements 10, 10 ', 10 "and 10"' being removed before the treatment of the second PE sample. The

Treatment parameters for the two PE samples (in particular the distance between the plasma nozzle 4 and the workpiece surface 18 and their relative speed to one another, plasma energy, rotational speed of the nozzle head 16, etc.) were otherwise the same.

The surfaces of both PE samples were then wetted with water and, using a camera system, at 23 points each along a diagonal across the entire treatment track, i.e. from the left edge of the treatment track (position -11) over the center of the treatment track (position 0) to the right edge of the

Treatment trace (position +11), which determines the contact angle between the activated PE surface and the water.

6 shows an overview of the results of these contact angle measurements. The lower graph shows the measured contact angles in degrees (°) for the respective measuring positions (from -11 to 11), whereby the solid lines of the first PE sample (with

Deflection elements 10, 10 ', 10 ", 10'") and the dashed lines correspond to the second PE sample (without deflection elements). The upper graph also shows the percentage deviation of the contact angle from the mean in percent (%).

It can be seen from FIG. 6 that the plasma treatment in the device used with the deflection elements 10, 10 ', 10 "and 10" "was carried out more homogeneously. The percentage deviation of the contact angle after a plasma treatment of the

Workpiece surface 18 with the deflection elements 10, 10 ', 10 ", 10'" is less than the percentage deviation of the contact angle after plasma treatment of the workpiece surface without deflection elements. 7 shows a rotating plasma nozzle with a nozzle opening which is inclined with respect to the axis of rotation 14, as is known, for example, from EP 1 236 380 A1. The plasma jet 6 emerges at an angle from the nozzle opening 8 of a nozzle head 16 rotating about an axis of rotation 14. The plasma nozzle 4 ″ shown in FIG. 7 can, for example, be used as the plasma nozzle 4 ′ in the exemplary embodiments according to FIGS. 3a-c and 4a-c. When the nozzle head 16 rotates about the axis of rotation 14, the plasma jet 6 describes a circle on one

Workpiece surface 18 or, with additional relative movement to

Workpiece surface, a spiral trajectory (see Fig. 5a).

8 shows a further exemplary embodiment of the device. The device 3 has a plasma nozzle 4 ″ ″ with a deflecting element 11 that rotates as well

Deflection element has a convexly curved contact surface 12 which is positioned on the nozzle head 16 in such a way that the one emerging from the nozzle opening 8

Plasma jet 6 interacts with the contact surface 12, in particular grazes it. The deflecting element 11 is preferably mounted so that it can be adjusted such that the angle of the deflecting element 11 to the nozzle opening 8 (arrow 22) can be varied, preferably in a range of at least 45 °, in particular at least 75 °, and / or the position in the direction of the nozzle opening 8 (arrow 24) is variable.

The contact surface 12 has a small radius of curvature of less than 2 mm, so that the plasma beam 6 is bent away from the deflection element 11. At

If a contact surface 12 with a radius of curvature of more than 2 mm were used, the plasma beam 6 would instead be bent in the direction of the deflection element 11. The deflection element 11 can accordingly achieve an effect similar to that with an oblique nozzle opening. When the nozzle head 16 from FIG. 8 rotates about the axis of rotation 14, the plasma jet 6 describes a similar circular movement on a workpiece surface 18 (not shown) as in FIG. 7. In particular, the plasma nozzle 4 ′ ″ shown in FIG. 8 can be used as a plasma nozzle 4 'can be used for the exemplary embodiments according to FIGS. 3a-c and 4a-c. Compared to the plasma nozzle 4 "from FIG. 7, the device 3 from FIG. 8 has the advantage that the nozzle opening runs along the axis of the plasma nozzle, so that

Energy losses due to contacts of the plasma jet with the wall, in particular an oblique nozzle opening as in FIG. 7, are largely avoided. In addition, the device 3 from FIG. 8 can be made very compact, so that workpiece surfaces that are difficult to access can be treated more easily.

Claims

Patent claims

1. Device (2, 2 ', 2 ", 2"', 3) for treating a workpiece surface (18), with a plasma nozzle (4, 4 ', 4 ", 4'") which is used to generate an atmospheric plasma jet ( 6) is set up

wherein the plasma nozzle (4, 4 ’, 4”, 4 ’”) has a nozzle opening (8) from which an atmospheric plasma jet (6) emerges during operation,

characterized,

that in the area of the nozzle opening (8) a deflection element (10, 10 ', 10 ”, 10'”, 11) with a convexly curved contact surface (12) is positioned such that the plasma jet (6) during operation of the plasma nozzle (4, 4 ', 4 ”, 4”') with the

Contact surface (12) of the deflection element (10, 10 ’, 10”, 10 ”’, 11) interacts, especially this grazes.

2. Device according to claim 1,

characterized,

that the deflection element (10, 10 ″, 10 ”, 10” ’, 11) consists of an electrically insulating material, in particular glass or ceramic.

3. Device according to claim 1 or 2,

characterized,

that the deflection element (10, 10 ’, 10”, 10 ”’, 11) is rod-shaped, in particular in the form of a cylinder or polygonal rod.

4. The device according to claim 3,

characterized,

that the deflecting element (10, 10 ', 10 ”, 10”', 11) extends transversely to the direction of the nozzle opening (8).

5. Device according to one of claims 1 to 4,

characterized in that the deflecting element (10, 10 ', 10 ”, 10'”, 11) is adjustable so that the positioning of the deflecting element (10, 10 ', 10 ”, 10”', 11) to the nozzle opening (8) to change.

6. Device according to one of claims 1 to 5,

characterized,

that the contact surface (12) has a radius of curvature of at most 2 mm.

7. Device according to one of claims 1 to 5,

characterized,

that the contact surface (12) has a radius of curvature of more than 2 mm.

8. Device according to one of claims 1 to 7,

characterized,

that a further deflection element (10, 10 ', 10 ", 10"') with a convexly curved contact surface (12) is positioned in the area of the nozzle opening (8) such that the plasma jet (6) during operation of the plasma nozzle (4, 4 ', 4 ”, 4”') with the contact surface (12) of the further deflecting element (10, 10 ', 10 ", 10"')

interacts, especially this grazes.

9. The device according to claim 8,

characterized,

that the deflecting element (10, 10 ', 10 ", 10'") and the further deflecting element (10, 10 ', 10 ", 10'") are positioned on opposite sides of the nozzle opening (8).

10. The device according to claim 8,

characterized,

that the deflecting element (10, 10 ', 10 ", 10"') and the further deflecting element (10, 10 ', 10 ", 10'") are positioned on the nozzle opening (8) such that the

Extension direction of the deflecting element (10, 10 ', 10 ", 10'") and the

Direction of extension of the further deflection element (10, 10 ', 10 ", 10'") run at an angle to one another, preferably at a right angle.

11. The device according to one of claims 8 to 10,

characterized in that the contact surface (12) of the deflection element (10, 10 ', 10 ", 10'") and the contact surface (12) of the further deflection element (10, 10 ', 10 ", 10'") have different curvatures.

12. The device according to one of claims 1 to 11,

characterized,

that the plasma nozzle (8) has a nozzle head (16) rotating during operation about an axis of rotation (14), the nozzle head (16) having the

Has nozzle opening (8).

13. The apparatus according to claim 12,

characterized,

that the direction of the nozzle opening (8) is at an angle to the axis of rotation (14), and

that the deflecting element (10, 10 ', 10 ", 10"', 11) is positioned such that the plasma jet (6) at least temporarily with the contact surface (12) during a full rotation of the nozzle head (16) about the axis of rotation (14) ) of the deflecting element (10, 10 ', 10 ", 10"', 11) interacts.

14. The apparatus of claim 12 or 13,

characterized, that the nozzle opening (8) of the nozzle head (16) is arranged eccentrically to the axis of rotation (14).

15. The apparatus according to claim 12,

characterized in that the deflecting element (11) is non-rotatably positioned on the nozzle head (16).

16. A method for treating a workpiece surface (18) with a device (2, 2 ″, 2 ″, 2 ’”, 3) according to one of claims 1 to 15,

in which the plasma nozzle (4, 4 ', 4 ”, 4'”) is used to generate an atmospheric plasma jet (6) which emerges from the nozzle opening (8) of the plasma nozzle (4, 4 ', 4 ”, 4'”) , wherein the plasma jet (6) with the contact surface (12) of the

Deflection elements (10, 10 ’, 10”, 10 ’”, 11) interacts, in particular grazes, and

in which the plasma jet (6) is directed onto the workpiece surface (18) to be treated.

17. The method according to claim 16,

characterized,

that the plasma nozzle (4, 4 ″, 4 ”, 4” ’) and the workpiece surface (18) are moved relative to one another in one direction of movement (20) and

that the deflection element (10, 10 ’, 10”, 10 ”’, 11) is positioned on the side of the nozzle opening (8) in or against the direction of movement.

18. The method according to claim 16,

characterized,

that the deflection element (10, 10 ’, 10”, 10 ”’, 11) is positioned on one side of the nozzle opening (8) transversely to the direction of movement.