DE102004047050B3 - Cleaning method for workpiece to be lacquered using CO2 snow, using core jet of CO2 snow surrounded by outer jet of compressed air at lower speed - Google Patents

Abstract

The method involves deflecting onto the workpiece a core jet (2) of CO2 snow at a speed of more than 200 m/s, and an outer jet (3) of compressed air, surrounding the core jet. The outer jet has a lower speed than the core jet. The speed is preferably less than 50% of the speed of the core jet. An independent claim is included for a nozzle for emitting CO2 snow and compressed air.

Description

The The invention relates to a method for treating a workpiece and a nozzle for CO2 snow. The invention also relates to a nozzle for the directed ejection of CO2 snow, especially for cleaning workpieces.

In front the painting of a workpiece this is cleaned and freed from dirt. Here is in the The past has been considered, including CO2 snow or crystals as a cleaning agent in a jet use.

In the DE 19926119 C2 is a jet tool for generating a beam of CO2 snow for cleaning microsystems or precision engineering described. In this jet tool, CO2 snow is generated in a capillary and admixed by a supersonic velocity support jet. The overall jet thus generated contains CO2 particles and is used for cleaning small parts such as a microchip.

The Blasting tool of the prior art is not applicable to to clean workpieces over a large area in a painting facility. In particular, the capillary arrangement only allows a very low throughput of CO2 snow and is not for the wide industrial application suitable.

task The present invention was therefore a method of treatment, in particular for cleaning a workpiece to be painted with CO2 snow provide. It is another object of the invention to provide a nozzle for cleaning with CO2 snow and compressed air to meet the requirements the industrial cleaning is sufficient.

The Task is solved by a method of treatment, in particular cleaning, a to be painted workpiece with CO2 snow being a core of CO2 snow at a speed of more than 200 m / s with a sheath jet surrounding the core jet compressed air on the workpiece is steered, wherein the sheath jet a lower speed as the core beam has. By such a method, in the core jet consists of CO2 snow at high speed again surrounded by a slower jet of compressed air is, the core ray can well defined and constant over one larger route on a workpiece be applied. By the combination of a slower coat jet From compressed air are all disturbing influences, the would change the geometry of the core beam. In this way is the defined core beam of CO2 snow with over Stretching constant parameters can be generated and can therefore also on workpieces be foreseeably applied, the larger undercuts or have different distance to the cleaning nozzle.

at a further advantageous method of the present invention the mantle jet has a speed of less than 80%, preferably less than 75%, more preferably less than 50% the speed of the nuclear jet. It has been surprisingly found that the mantle jet also at much lower speeds as the core jet causes a high shielding effect against disturbing external influences and contributes to the stabilization of the core beam. This is how the core ray can be again undisturbed act on the workpiece.

at a further advantageous method of the present invention is the relationship the speed of the mantle jet to the speed of the Core jet adjustable. By the choice of the ratio the velocity of the sheath jet to the velocity of the core jet the geometry of the core beam is influenced. In this way Is it possible, to make the beam shaping of the core beam.

at a further advantageous method of the present invention the core jet has a speed of more than 333 m / s. With the choice of supersonic range for the Kernstrahl it is possible to achieve particularly high cleaning effects.

at a further advantageous method of the present invention the core jet has a diameter of 30 mm. Especially Preferably, the diameter of 30 mm is about 80 mm behind a nozzle end generated and for another 200 to 300 mm kept constant on this diameter. A variation of the diameter of the beam focus is, for example through the change the speed of the sheath current and / or the choice of temperature gradients between sheath current and core current possible.

at a further advantageous method of the present invention the cladding jet has an outer diameter of about 200 to 250 % of the diameter of the core jet.

at a further advantageous method of the present invention is the geometry of the core ray by varying the velocity of the Sheath jet adjustable.

In a further advantageous method According to the present invention, the jacket jet of compressed air has a higher temperature than the core jet of CO2 snow.

at a further advantageous method of the present invention becomes the workpiece painted after processing.

The Task is also solved through a nozzle for directional ejection of CO2 snow and compressed air being a central area of the nozzle at least a first discharge opening that's running is at a supersonic velocity around a CO2 snow core to produce the central region of the nozzle from a peripheral region is surrounded, which has a plurality of second discharge openings, the (preferably symmetrical) around the first discharge opening are arranged around and executed are to a surrounding the core jet air jet with compressed air to produce lower speed than the core stream, wherein the cladding jet has the same direction as the core jet. Through such a nozzle a core of CO2 snow can be generated that has this one has surrounding jacket jet of compressed air and so on a cleaning jet can bring a workspace that is sufficiently dimensioned is sustainable to even larger areas to be able to clean. Preferably, the core beam is formed by CO2 snow by relaxation is formed by CO2 and by means of compressed air within a CO2 gun as a mixed jet of CO2 and compressed air with high Speed is generated at the exit. Instead of compressed air Another gas can be used. A nuclear jet produced in this way is then a mixed jet of CO2 snow and compressed air. Surrounded this core jet from a jacketed jet of pure compressed air, the shields the core against external influences. In this way it is possible workpieces to clean before a painting step, within a short time with a transport device on such a CO2 pistol with this Nozzle be passed.

In a further advantageous embodiment of the present invention Invention is a tempering device for controlling the temperature the mantle jet of compressed air and or the core jet of CO2 snow intended. By controlling the temperature in particular of the Mantelstrahls it is possible to influence the geometry of the core beam. Preferred is a Temperature of the sheath jet of less than 10 ° C, more preferably less as 4 ° C used.

In a further advantageous embodiment of the present invention Invention is a control device for adjusting the speed the jacket jet of compressed air and / or the core jet of CO2 snow, especially independently of each other, intended. By adjusting the speed of the jacket jet can also change the geometry of the core and thus the focus and the working range of the core beam can be varied.

In a further advantageous embodiment of the present invention Invention, the first discharge opening for the core jet is designed as a Laval nozzle. By choosing the Laval nozzle CO2 snow can reach very high speeds, particularly supersonic speeds, be accelerated and the nozzle leave with it. The combination of this very high speed the core jet on the one hand and the surrounding the core jet jacket jet from compressed air on the other hand, which prevents disturbing influences from the core jet, allow the application of the core jet to the working area of a to be cleaned Workpiece over long distances which also makes it possible to clean profile parts and three-dimensional bodies.

In a further advantageous embodiment of the present invention Invention are supplies for the compressed air inside the nozzle in a section in front of the discharge openings parallel to feeders for the CO2 snow led out. By this constructive measure will be a lower height the nozzle possible. About that Beyond those are the forces ideal in the nozzle recorded and preferred with the exit direction of the two beams aligned.

The object is also achieved by a carousel support for receiving at least one nozzle according to the invention comprising a rotating device, which is designed such that the at least one nozzle is movable in rotational movements over a working range. Through the use of a carousel carrier, as he also for example in the utility model DE 29814293 U1 If the applicant is described for another field of application, cleaning becomes even more efficient for workpieces with undercuts. On such a carousel carrier, preferably at least one nozzle is arranged on a rotatable hub, so that upon rotation of the rotating device by the cleaning jet a circle or an ellipse in a plane on the working area is described. Particularly preferably, the nozzle is made obliquely, so that undercuts can be cleaned because the beam in the rotating movement of the rotating device describes a conical section in space and not just a cylinder. This oblique orientation of the individual nozzle so that the workpiece not only frontally but also in the undercut area cleaned from the side. Especially be Preferably, the rotating device is (co-) driven by repulsive forces of the jet emerging from the nozzle. In this way it is possible to save an additional drive for the rotating device. However, it is also advantageously possible to provide a special speed or speed curves for the rotating device via a corresponding control device for the rotating device, with which special geometries can then be cleaned particularly efficiently. Particularly preferably, a plurality of nozzles, more preferably three nozzles, are provided on the carousel support or the rotating device. In addition, it is advantageous to form the rotating device or the carousel itself again transversely to the conveying direction of the workpiece to be machined, so that the carousel or the rotator perpendicular or oblique to the conveying direction, for example, a conveyor belt on which the workpieces are stored back and can be moved. In this way a very complete workspace is described. In this case, the angle of attack of the individual nozzle of the carousel carrier is preferably set differently, so that a large work area can be coated extensively and uniformly by the rotational movement of the individual nozzles on the one hand and the transverse movement of the entire Krausselträgers.

advantageous Embodiment and other embodiments be in the attached Drawings explained. Hereby shows:

1 a sectional view of an embodiment of the nozzle according to the invention;

2 an external view of an embodiment of the nozzle according to the invention;

3 a schematic representation of the core jet and the cladding jet after exiting a nozzle according to the invention; and

4 a view of a carousel carrier according to the invention with nozzles according to the invention.

In 1 is a section along the points A'A of a nozzle according to the invention as well as in 2 shown. The nozzle 1 indicates a central conveying area for CO2 snow along the arrow. This channel opens into a first discharge opening 6 located in a central area 5 the nozzle 1 located. This central area is circular, as is the first discharge opening. Adjacent to this is circular around the central area 5 the nozzle 1 around a peripheral area 7 the nozzle 1 arranged. In this peripheral area are a plurality of slit-like second discharge openings 8th provided, from which then compressed air can be promoted. The delivery lines for the compressed air are routed in the middle section of the nozzle parallel to the central conveyor area for CO2 snow.

In use, it is now possible, along the arrow shown to promote CO2 snow, over the first discharge opening 6 , which is pictured as a Laval nozzle at supersonic velocity from the nozzle 1 in the central area of the nozzle 5 withdraw. Through the different slots 8th is compressed air from the peripheral area 7 the nozzle 1 herausgefördert and thus forms a sheath jet around the core beam escaping in the central region.

In 2 the nozzle is off 1 shown again in a schematic overall view. In particular, the slot-shaped second discharge openings can be used here 8th in the peripheral area 7 Detect the nozzle around the first discharge opening 6 in the central area 5 the nozzle are arranged. Through these slot-shaped discharge openings 8th is formed a uniformly surrounding the core jet cladding beam, which completely surrounds the CO2 snow core jet and can be separated from external influences.

In 3 is schematically the exiting core beam 2 and the surrounding sheath jet 3 represented over a length L. Out of the nozzle 1 occurs over the first discharge opening 6 a mixture of CO2 snow and compressed air as a core jet 2 at supersonic speed along the central, thicker arrow shown. Next to it is a jacket jet 3 generated by compressed air, that from the second discharge openings 8th Compressed air at a slower speed than the core jet 2 exit and a jacket jet 3 around the core ray 2 forms around. After a distance A from the nozzle head, preferably after about 80 mm, forms over a length L, an area in which the diameter of the core beam 2 is kept largely constant and the sheath jet 3 is surrounded. The jacket jet 3 has a lower velocity than the core jet 2 on. The length L is preferably about 200 to 500 mm, more preferably about 200 to 300 mm.

By choosing the speed ratio of the cladding jet 3 to the core ray 2 can the geometry of the core beam 2 be influenced as well as by the choice of the temperature of the cladding jet 3 opposite to the temperature of the core jet.

In 4 becomes a carousel carrier according to the invention 20 , on the three nozzles according to the invention 1 are mounted, shown.

A drive motor for rotation forms the drive 22 its force on a V-belt on a rotary tube 24 can be transferred. Through the rotary tube 24 can supply the three nozzles via a rotary feedthrough for compressed air and liquid CO2 1.1 to 1.3 respectively.

The nozzles 1.1 to 1.3 consist of a CO2 snow blasting gun 29 that has an entrance opening 27 for compressed air and another inlet 28 for CO2, here shown with control valve, are provided. A pistol shot 26 with integrated scale graduation is provided to perform reproducible settings of the beam direction.

About the drive 22 becomes the rotary tube 24 and thus the entire carousel carrier is brought into rotation, leaving the three nozzles 1.1 to 1.3 come to rotate about the axis of rotation of the rotary tube. By adjusting the jets that emerge from the nozzle, preferably via the gun holder 26 the beam direction can be adjusted so that the area to be machined on the workpiece is optimally traversed. By the between the drive motor 22 and the rotary tube provided V-belt, the rotation speed is directly from the drive motor 22 controlled. It would also be conceivable to provide a clutch such that via the drive motor 22 only a basic speed is mediated and other speed components is supported by a recoil behavior of the jet from the nozzle. It is particularly preferably possible again to guide the entire carousel support, for example transversely over the workpiece or in the direction of the workpiece along the arrows shown, so that in addition to the rotational movement of the carousel support a transverse movement, for example a reciprocating motion over the workpiece and / or takes place on the workpiece, so that the three rotating cleaning jets can be applied more evenly and more widely distributed over the area of the workpiece.

By this invention became a nozzle for directional ejection of CO2 snow and compressed air for cleaning workpieces as well a method provided therefor, according to the industrial scale over a constant Work areas towards a high cleaning performance, preferably for Pretreatment of workpieces in a painting, can be achieved.

1

jet

2

core jet

3

jacketed jet

5

centrally Area of the nozzle

6

first discharge opening

7

peripheral Area of the nozzle

8th

second discharge opening

10

tempering

12

control device for speed

20

Karusselträger

22

drive

24

rotary tube for supply lines

25

Rotary union

26

gun mounting

27

Inlet opening compressed air

28

Inlet CO2

29

CO2 Snow blasting gun

Claims (14)

Process for the treatment, in particular cleaning, of a workpiece to be coated with CO2 snow, whereby a core jet ( 2 ) from CO2 snow at a velocity of more than 200 m / s with a sheath jet surrounding the core jet ( 3 ) is directed from compressed air to the workpiece, characterized in that the sheath jet ( 3 ) a lower velocity than the core jet ( 2 ) having. Method according to claim 1, wherein the jacket jet ( 3 ) a speed of less than 80%, preferably less than 75%, more preferably less than 50% of the speed of the core jet ( 2 ) having. Method according to one of the preceding method claims, wherein the ratio of the speed of the jacket jet to the velocity of the core jet ( 2 ) is adjustable. Method according to one of the preceding method claims, wherein the core jet ( 2 ) has a speed of more than 333 m / s. Method according to one of the preceding method claims, wherein the core jet ( 2 ) has a diameter of 30 mm. Method according to one of the preceding method claims, wherein the jacket jet ( 3 ) an outer diameter of 200 to 250% of the diameter of the core jet ( 2 ) having. Method according to one of the preceding method claims, wherein the geometry of the core beam ( 2 ) by varying the velocity of the jacket jet ( 3 ) is adjustable. Method according to one of the preceding method claims, wherein the jacket jet ( 3 ) from compressed air at a higher temperature than the core jet ( 2 ) of CO2 snow. Jet ( 1 ) for the directed ejection of CO2 snow and compressed air for carrying out the method according to one of the preceding claims, wherein a central region ( 5 ) of the nozzle ( 1 ) at least one first discharge opening ( 6 ), which is designed to be a core of CO2 snow ( 2 ) at supersonic velocity, the central region ( 5 ) of the nozzle ( 1 ) from a peripheral area ( 7 ), which has a plurality of second discharge openings ( 8th ) which surround the first discharge opening ( 6 ) are arranged around and are designed to provide a core jet ( 2 ) surrounding jacket jet ( 3 ) from compressed air at a lower speed than the core stream ( 2 ), wherein the cladding jet ( 3 ) the same direction as the core beam ( 2 ) having. Jet ( 1 ) according to claim 9, wherein a tempering device ( 10 ) for controlling the temperature of the jacket jet ( 3 ) of compressed air and / or the core jet ( 2 ) is provided from CO2 snow. Jet ( 1 ) according to one of claims 9 or 10, wherein a control device ( 12 ) for adjusting the speed of the jacket jet ( 3 ) of compressed air and / or the core jet ( 2 ) of CO2 snow, in particular independently of one another, is provided. Jet ( 1 ) according to one of claims 9 to 11, wherein the first discharge opening ( 6 ) is designed as a Laval nozzle. Jet ( 1 ) according to one of claims 9 to 12, wherein feeds for the compressed air within the nozzle ( 1 ) are provided in a section in front of the discharge openings in parallel with feeders for the CO2 snow. Carousel support for receiving at least one nozzle ( 1 ) according to one of claims 9 to 13 comprising a rotating device, which is formed so that the at least one nozzle is movable in rotational movements over a working range.