EP3448590B1 - Method and device for cleaning metal workpieces - Google Patents

Description

TECHNICAL AREA

The invention relates to a method for cleaning metal workpieces having the features of the preamble of claim 1 and a device suitable for carrying out the method having the features of the preamble of claim 7.

STATE OF THE ART

In mass production, metal workpieces are often processed and finished on automatic production lines. Such processes play a particularly important role in the automotive industry. Machining processes are often used in which lubricants are used and chips and burrs are produced. So-called minimum quantity lubrication has recently become established, in which only small quantities, for example <100 (minimum quantity cooling lubrication, MQL) or even <20 ml/h (minimum quantity lubrication, MQL), of the cooling lubricant are used. Among other things, this has the advantage that only very small amounts of liquid waste occur and that the chips produced are not contaminated and can easily be recycled. Before such workpieces are further processed or assembled in assemblies, contamination, such as residues of the cooling lubricant, must be removed. Numerous methods are known for this purpose, using aqueous or non-aqueous solvents, with aqueous solvents being preferred recently because they cause less costs and environmental problems.

The workpieces are usually immersed in the solvent and/or treated with a jet of the solvent.

Not only lubricant residues and chips are removed, but also annoying burrs.

In the DE 44 10 550 C1 describes a method for drying workpieces, which have been subjected to a cleaning and rinsing process, in a pressure-tight chamber, the parts in the chamber first being heated by water vapor introduced at overpressure, the parts first being rinsed by the condensation water formed. If the pressure is then reduced below atmospheric pressure, if necessary, then the residues of condensation water on the surface of the parts evaporate, which can then be taken out of the chamber dry. The parts are subject to strong temperature fluctuations, for example from over 100 °C to almost 0 °C.

In industrial cleaning processes, the use of negative pressure for the purpose of drying cleaned workpieces in so-called "vacuum drying" is known. Drying takes place in a separate work step after the actual cleaning.

DE 10 2007 027 944 A1 discloses a method and a device for cleaning objects that are contaminated with oily or greasy processing residues by means of a high-pressure steam jet in a closed treatment chamber under a pressure that is lower than atmospheric pressure, in which high-pressure steam jet cleaning or abrasives are introduced. With this method, too, the workpiece is subject to strong temperature fluctuations. It is provided that a liquid jet hitting the workpiece 2 with high energy, also steam or gas jet, emits residues on the workpiece and swirls them around in the treatment chamber 1 . A chaotic atomization of the cleaning jet is thus effected, which ensures neither that the entire workpiece surface is irradiated nor that the dirt particles loosened by the jet from the

Workpiece surface can be completely removed.

It has been shown that it is disadvantageous if, after cleaning and, if necessary, drying, the parts have a significantly different temperature than the environment in which further processing or assembly is to take place. For example, a workpiece made of aluminum (linear thermal expansion coefficient 23 * ^10-6 ) with a diameter of 100 mm becomes 23 µm larger when heated by 10 K. If it is installed in a correspondingly large bore, the character of the fit changes as a result of temperature compensation. On the other hand, with further processing there is a risk that too much material will be removed. The workpiece must therefore be tempered before assembly, which requires a noticeable amount of time in the case of larger objects.

DE19609119A1 describes another purification method. The workpiece is to be cleaned in a treatment chamber in which negative pressure prevails. In order to come into contact with the cleaning agent, the workpiece is rotated within the treatment chamber. In many cases, however, simply wetting the workpiece surface is not enough to remove adhering dirt.

At the in JP S58210888 A described cleaning device, a workpiece within a treatment chamber is sprayed from several sides at the same time. Here, too, there is no guarantee that partially dissolved dirt particles will be completely removed from the surface and will not be deposited elsewhere.

OBJECT OF THE INVENTION

The object of the invention is to specify a method with which metal workpieces, in particular after machining with minimum quantity lubrication, are cleaned and can optionally be dried, with the temperature of the workpiece remaining within a range that allows further processing or assembly without prior tempering. A further object consists in specifying a device with which this method can be carried out.

These objects are achieved by a method according to claim 1 and a device according to claim 8.

Surprisingly, it was found that when cleaning with a jet of steam and/or hot water, in particular steam, the impurities present can be stripped off the workpiece if such a jet is scanned relative to the surface of the workpiece if at the same time a Negative pressure is set compared to the external atmospheric pressure. The water remaining on the surface is evaporated by the negative pressure and the heat supplied by the steam or hot water is at least partially withdrawn from the processed area, so that this area resumes the temperature prevailing before the processing before the heat penetrates the workpiece can spread. The contaminants are transported with the possibly condensed water both in the scanning direction over the surface and can drip off into a sump at the end of the scanning path, and also removed from the surface by spraying. Only pure water remains at the point of impact, possibly from the condensation of the steam, which can evaporate without residue due to the negative pressure.

Before passing through the nozzle, the hot water preferably has a temperature of 70 to 95°C. If steam is used, it preferably has a pressure of 0.2 to 1 MPa, particularly preferably 0.2 to 0.4 MPa, in particular 0.3 MPa (absolute) and a temperature of between 120 and 200° before passing through the nozzle C, particularly preferably 135 to 160 °e, in particular 140 °C

The use of steam, in particular superheated steam (unsaturated steam or dry steam) or saturated steam, is preferred. Water without additives is preferably used to generate steam.

An electrode steam generator is preferably used to generate steam. Here preferably no demineralized water is used, but water with sufficient conductivity, in particular with a mineral content, e.g. tap or well water. The water can be circulated in particular in the circuit.

Regarding the relative movement of the jet, "scanning" means in this context that the point of impact, i.e. the point at which the jet of steam or hot water hits the surface of the workpiece and impurities from the surface are absorbed in the water or condensed water, on a continuous path in the direction from one end of the workpiece to the other end. This scanning path can have a continuous course from one end to the other or can also consist of several sections. If there are a number of nozzles for jet generation, there can be a number of scanning paths assigned to the individual nozzles, or it is also possible for individual or all nozzles to contribute only one section to a scanning path. In the simplest case, so many nozzles can be arranged around the workpiece that the corresponding scanning points overlap and the entire surface of the workpiece can be cleaned and dried with a simple linear movement.

The reduced pressure in the closed container is preferably between 850 and 20 hPa absolute, particularly preferably between 100 and 300 hPa absolute.

In a preferred embodiment, the method according to the invention can be carried out in such a way that the residues of water remaining on the workpiece surface evaporate completely, i.e. the workpiece surface is dried in the same work step as the cleaning. Since the workpiece is then dry and tempered, it can be further processed or assembled immediately.

The scanning of the surface of the workpiece is carried out in such a way that the scanning point moves on a helical path which results from the superposition of a circular movement and a linear movement. Here, the contaminants are transported continuously in a direction opposite to that of the linear movement, towards the end of the workpiece. One nozzle is sufficient for such an embodiment. The linear movement can be continuous. However, it can also be carried out step by step, for example after one or more complete circular movements.

The scanning is carried out by moving the workpiece, the nozzle or both parts, with the workpiece being guided in particular linearly past an arrangement with at least one nozzle rotating about an axis parallel to its own axis.

The circular movement can be effected in a simple manner, for example, by rotating the workpiece about an axis which coincides with the directional axis of the linear movement. But it is also possible to move the nozzle on a closed path around the workpiece. It can be expedient to bring the nozzle back to the starting point after completing a circular path in order to facilitate the supply of steam or hot water to the nozzle. Linear motion can be stopped during retraction.

In a preferred embodiment, there are multiple nozzles present, which are arranged in the direction of the linear movement and/or in a plane around the workpiece, preferably at equal angular distances in each case. In the latter case, it can be advantageous if the nozzles do not describe complete circular movements but only circular arcs, the length of which can correspond, for example, to the angular distance or a multiple thereof. After moving through such an arc, they are returned, resulting in an oscillating motion. This makes it easier to supply the nozzles with steam or hot water. Instead or in addition, the workpiece can also be moved in an oscillating manner about an axis. This axis is preferably the direction of linear movement.

Furthermore, it is advantageous to carry out the movement in such a way that its direction is vertical, that is to say, for example, to move the workpiece vertically from bottom to top and/or to move the nozzles from top to bottom. Gravity assists in transporting the contaminants and cleaning water to the bottom of the tank and to the sump.

In a further advantageous embodiment, this transport is also promoted if the nozzles are arranged in relation to the workpiece in such a way that the jet of steam or hot water forms an angle between, for example, 90° and 135°, preferably between 90° and 105°, with the direction of the linear movement. forms, that is directed obliquely downwards. In order to be able to clean the entire surface of more complicated workpieces with blind holes, undercuts and the like, additional nozzles can preferably be attached, in which the jet of steam or hot water is perpendicular to the linear movement or at an angle of, for example, 45 to 90°, preferably 75 to 90°, i.e. directed obliquely upwards.

In a further preferred embodiment, there are one or more nozzles on a for example cross or disc-shaped nozzle carrier, which is further preferably set up rotatably. The jet directions of the one or more nozzles can form an angle of 0 to 45°, preferably 0 to 15°, with a perpendicular to the surface to be treated, ie can be aligned perpendicularly or obliquely to this surface. By rotating the nozzle carrier, the direction of the inclined position may change. In particular, nozzles from different directions within the stated limits can also be arranged on a nozzle carrier. This further improves the cleaning effect on complex components (with jagged surfaces). The invention is particularly suitable for machined metal workpieces.

The speed of a rotating nozzle carrier is preferably above 750 min ^-1 , particularly preferably between 1250 min ^-1 and
1750 ^rpm , especially at 1500 ^rpm .

When arranging the nozzles on a nozzle carrier, a certain area around the axis of rotation can be left free. This area can be provided with a rotor blade structure, possibly with openings on the rear side, and then generates a suction effect away from the workpiece as a result of the rotation, which promotes the removal of condensate and water vapor as well as drying.

The water running down from the workpiece as well as the spray water running down the inner wall of the container collects in a sump at the bottom of the container and can be sucked off or drained from there.

The method according to the invention can be supplemented by applying, preferably spraying, an aqueous solution of a cleaning agent to the surface of the closed container before the workpiece is placed in the closed container for cleaning and drying, as is the case, for example, in pending patent application DE 10 2014 101 123 A1 is described.

Here, a cleaning concentrate containing at least 0.5 percent by weight of a nonionic or anionic surfactant is applied to the workpiece. The nonionic surfactant can be an alkoxylate of a fatty alcohol having from 6 to 22 carbon atoms in the alkyl group. The anionic surfactant can be a sulfate, sulfonate, or carboxylic acid having an aliphatic, aromatic, or aliphatic-aromatic hydrocarbyl group. The cleaning solution can also be applied by temporarily immersing it in a bath.

In a particularly preferred embodiment, the surface temperature of the workpiece behind the point of impact, viewed in the direction of movement, is measured without contact. The vacuum and mass flow of the steam or hot water are then regulated in such a way that the desired surface temperature, for example the temperature in the workpiece before cleaning or the temperature prevailing during further processing or assembly, is achieved. This can prevent the workpiece temperature from being changed by the use of the method according to the invention and thus the dimensions of the workpiece being changed.

The method is preferably carried out in such a way that the temperature of the workpiece after the end of the cleaning and, if necessary, drying does not deviate by more than 2 K from the temperature before the cleaning. However, it is of course also possible to carry out the method in such a way that a predetermined temperature change results.

The invention also includes an apparatus for carrying out the method described above, having the features of the preamble of claim 7.

These means for adjusting the mass flow can, for example adjust either the pressure of the water or steam, or the flow resistance of the lines and nozzles, or both. The flow resistance can be adjusted, for example, by means of throttle valves, variable orifices or the like.

The device according to the invention preferably comprises a nozzle arrangement in which a plurality of nozzles are arranged on at least one closed curve surrounding the workpiece. This closed curve can be, for example, a circle in a plane or else a zigzag-shaped closed line. Closed curves are also possible, which are specially adapted to the shape of the workpiece. As a result, the workpiece can be completely cleaned with a simple linear movement, optionally combined with an optionally oscillating rotation.

The at least one nozzle arrangement of the device according to the invention comprises at least one nozzle which can rotate about an axis which is parallel to and/or spaced from its own axis. Several nozzles can also be mounted on a rotating head.

The scanning path generated by such a nozzle arrangement is then created by superimposing a circular movement and the linear movement of the workpiece and/or the nozzle arrangement. The nozzles can also be aligned at an angle of, for example, 0 to 45°, preferably 0 to 15°, to the axis of rotation.

In a preferred embodiment, the nozzles are attached to a multi-armed nozzle carrier in such a way that a central area around the axis of rotation remains free of nozzles. The nozzle carrier can be provided with a rotor blade structure, possibly with openings to the rear, so that during rotation a suction effect occurs from the nozzle side to the rear.

In a further embodiment, the holder for the workpiece is also used as a closure for the opening of the treatment chamber. This can be easily implemented if the holder can be moved into and out of the treatment chamber.

The device preferably also comprises means with which the surface temperature of the workpiece can be measured at at least one specific point. In order to avoid disrupting the cleaning and, if necessary, drying process, means for non-contact measurement are preferred. These can be infrared thermometers, for example, in which the area of the workpiece to be measured is imaged by infrared optics on a suitable detector, and this measuring line can also be adjusted to the emission properties of the workpiece surface.

If the temperature of the workpiece surface can be measured behind the point of impact, it is possible to manually adjust the flow of steam or hot water and the vacuum to achieve the desired surface temperature. However, the device according to the invention preferably comprises a control device which automatically controls either the steam or hot water flow or the negative pressure or both on the basis of the measured surface temperature and its deviation from a set setpoint.

Since the inner wall of the container can also be contaminated by splashing of the cleaning water containing the removed contaminants, it is advantageously coated with a dirt and water-repellent substance such as polytetrafluoroethylene or silicone resin.

The inventive method can be incorporated into automatic production processes, it being between the machining or forming and assembly can take place. Since it allows cleaning and drying in one operation, the entire process is simplified. In particular, it is suitable for the automated cleaning and, if necessary, drying of components in the automotive industry, in particular components of internal combustion engines, for example engine blocks, cylinder heads, crankshaft housings, transmission housings and the like.

The method according to the invention can easily be integrated into the cycle of corresponding production lines. For example, the usual cycle time of the process in the manufacture of cylinder heads or engine blocks for passenger car engines can be broken down in three roughly equal parts into the actual cleaning and drying process, ventilation and opening of the vacuum chamber and changing the workpiece with closing the chamber and creating the vacuum be divided, for example, each about 10 s at a cycle time of about 30 s in total. The process is suitable for workpieces made from a variety of materials, such as iron, gray cast iron, steel, brass, bronze, zinc and its alloys. In particular, it is advantageous for materials made of light metals, which typically have higher thermal expansion coefficients. Examples are aluminum, aluminum alloys with silicon, magnesium, copper, in particular cast aluminum alloys, magnesium, magnesium alloys, titanium and its alloys. The method according to the invention greatly reduces the amount of contaminated waste water compared to the prior art, resulting in a reduction in costs.

The energy consumption in the method according to the invention can be kept comparable or even lower than in conventional cleaning with compressed air. In doing so, however, the surface is completely freed from moisture, lubricant residues and other contaminants, which is not possible with compressed air.

BRIEF DESCRIPTION OF THE FIGURES

• Figur 1 zeigt einen schematischen Längsschnitt durch eine erfindungsgemäße Vorrichtung nach einer ersten Ausführungsform.
• Figur 2 zeigt eine schematische Seitenansicht des Werkstücks mit der eingezeichneten Abtastbahn der Vorrichtung nach Figur 1.
• Figur 3 zeigt einen schematischen Querschnitt durch eine erfindungsgemäße Vorrichtung nach einer zweiten Ausführungsform.
• Figur 4 zeigt eine schematische Seitenansicht des Werkstücks mit eingezeichneten Abtastbahnen der Vorrichtung nach Figur 3;
• Figur 5 ein alternatives Ausführungsbeispiel mit Rückführung der Reinigungsflüssigkeit als vereinfachtes Flussdiagramm.

The invention is explained in more detail below with reference to the attached drawings by way of example and without limiting the scope of protection.

• figure 1 shows a schematic longitudinal section through a device according to the invention according to a first embodiment.
• figure 2 shows a schematic side view of the workpiece with the scanning path of the device shown figure 1 .
• figure 3 shows a schematic cross section through a device according to the invention according to a second embodiment.
• figure 4 shows a schematic side view of the workpiece with marked scanning paths of the device figure 3 ;
• figure 5 an alternative embodiment with recirculation of the cleaning liquid as a simplified flow chart.

DETAILED DESCRIPTION WITH THE FIGURES

In figure 1 a device for carrying out the method according to the invention is shown in a schematic longitudinal section. The device comprises a container 1 which is open at the top and can be closed in a vacuum-tight manner by a lid 2 with the participation of a seal 3 . The tank 1 continues downwards via a connecting pipe 13 to a sump tank 10 . A workpiece 4 to be cleaned is accommodated in the container 1 and held by a holder. For reasons of clarity, this holder and the passage through the edge of the container that may be necessary for the execution of the linear and rotary movement of the workpiece 4 are not shown here, but can easily be supplemented by a person skilled in the art. This Holder with the workpiece 4 can perform a rotational movement, described by the closed arrow 7, about an axis 5 and, at the same time, a linear movement in the direction of the arrow 6, which lies in the axis 5 here. The axis of rotation 5 of the workpiece is aligned vertically here.

During operation of the device, a sump 11 can form in the sump container 10 as a result of draining, possibly contaminated water, which can be drained or sucked off via a sump valve 12 .

A negative pressure can be generated in the container 1 when the pump 20 sucks air out of the interior of the container 1 via the vacuum line 21 . The vacuum line 21 can be connected to the sump tank 10 or also directly to the tank 1 .

A nozzle 27 is built into the wall of the container 1 and is connected via a line 26 to a steam or hot water generating unit. This unit can be controlled with regard to the pressure and temperature of the steam or hot water. This also allows the mass flow of the respective medium to be controlled. The nozzle 27 forms an obtuse angle α of about 110° in this case, for example, with the vertical or the axis 5 of the workpiece. The jet 28 of the medium (steam or hot water) strikes the surface of the workpiece 4 at an impact point at almost the same angle.

An infrared temperature sensor 31 is also installed in the wall of the container 1, in which the measuring point 36 on the surface of the workpiece 4 is imaged by infrared optics on a detector, which emits a signal corresponding to the surface temperature via a measuring line 32. To measure the negative pressure, a negative pressure sensor 30 is also installed in the wall of container 1, which sends a signal corresponding to the negative pressure in container 1 via a measuring line 33 gives.

A control unit 35 receives signals via the measuring lines 32 and 33 and controls the mass flow of the respective medium emitted by the generation of a 25 via the control lines 40 and 41 in such a way that the temperature measured by the temperature sensor 31 via the measuring line 32 assumes a specified setpoint value.

To clean and dry a workpiece 4, the container 1 is first opened by removing the cover 2 and the workpiece 4 is brought into the working position, where it is held by the holder (not shown) so that it can rotate and slide. It is initially in the lower starting position shown in dashed lines. The container 1 is sealed airtight by placing the lid 2 using the seal 3. The generating unit 25 and the vacuum pump 20 are now switched on via the control unit 35 and the linear and rotary movement of the workpiece 4 is initiated. The end face of the workpiece 4 and then the side face are first cleaned by the jet of steam or hot water 28 . After the temperature at the measuring point 36 sliding on the surface has been measured by the temperature sensor 31, the mass flow and negative pressure are regulated by the control unit 35 from the initially preset initial values in such a way that the preset setpoint temperature at the measuring point 36 results.

If steam is used for cleaning, impurities on the surface of the workpiece 4 are partially mechanically removed from the surface by the transmitted impulse of the steam jet and by dispersion in the water formed by condensation and carried away by the water. A jet of hot water has a similar effect. This water partially runs on and off the surface of the workpiece 4, partially it is splashed and reaches the inner wall of the container 1, where it can also drain downwards. Finally one stays Some of the water also returns to the surface, wetting it, and evaporates, removing heat from the surface. The draining water reaches the sump container 10 via the connection 13 and forms the sump 11, which can be drained through the valve 12, for example while the container 1 is open to change the workpiece, or can also be pumped out, for example continuously.

figure 2 illustrates the course of cleaning after the in figure 1 shown embodiment of the invention. Due to the linear movement of the workpiece 4, the steam or hot water jet first strikes the side surface of the workpiece 4 at the point of impact 51 and then travels along the imaginary scanning path 50 in a helical manner around the workpiece 4 until it has scanned the entire surface. The linear and rotary movements are coordinated in such a way that during one revolution of the workpiece 4 it is moved linearly by a stroke h. The point of impact 51, 52 is not punctiform, but due to the inclined position of the nozzle 27 approximately elliptical with a vertical major axis. As the successively reached impact points 52 show, there is a certain overlapping of the impact points in adjacent branches of the scanning path 50 . This repeats the cleaning process and improves the cleaning effect. The degree of overlap can be changed by adjusting the stroke h.

figure 3 shows schematically a second embodiment of the device according to the invention in cross section, only the modified components being shown. In this embodiment, four nozzles 68 are arranged in a plane on the periphery of the container 1 at the same angular distance from each other. These act on the surface of the workpiece 4 at the same time.

figure 4 illustrates the course of the through the nozzles 68 in figure 3 The embodiment shown generates four scanning paths 60 on the surface of the workpiece 4 Workpiece 4 moves linearly by the stroke in 1 revolution. Again, the impact points 61 of the adjacent scanning paths 60 overlap and the extent of the overlap can be adjusted by adjusting the stroke as needed.

To demonstrate the cleaning and drying effect, a cylinder head for a passenger car engine was treated according to the invention. A commercially available adhesive film was placed on a smooth, cleaned and dried surface and adhered firmly to it over the entire surface. In a comparative test with a cylinder head cleaned in the conventional way with compressed air, the adhesive film could not be attached to the same smooth surface either.

In figure 5 components that are structurally or functionally the same are denoted by the same reference numbers as in Figure 1-4 .

This exemplary embodiment differs primarily in the further development of the return circuit via which cleaning liquid is recovered from the treatment chamber 1 . The vapors generated by the negative pressure and the temperature are sucked out of the treatment chamber 1 via a first filter unit 71 by the vacuum pump 20 and then fed to a downstream second filter and separator stage 72 which has an oil separator 74 . The outlet of the filter unit 71 opens into the oil separator 74. On the outlet side, the vacuum pump 20 is connected to a condensation unit 73, the return of which also opens into the oil separator 74. The steam generator 25 is fed from a clean tank 75 in the second filter and separator stage 72 via a water pump 76 in a supply line 77 . The outlet pressure of the steam generator 25 and the suction effect of the vacuum pump 20 ensure that steam is injected with a high dynamic jet pressure. Through the cycle according to figure 5 In addition, residual heat from the recovered cleaning liquid is used, so that additional energy savings are achieved.

Fresh water is only supplied as needed because of the losses in the second filter and separator stage 72 .

figure 5 also schematically illustrates a holder 78 for the workpiece 4 that can be automatically moved into and out of the treatment chamber on two axes H, V. The holder 78 also forms a pressure-tight seal for the opening of the treatment chamber 1 in the working position.

REFERENCE LIST

1

container

2

removable lid

3

poetry

4

workpiece

5

axis of the workpiece

6

direction of linear motion

7

direction of rotation

10

sump tank

11

swamp

12

sump valve

13

connecting pipe

20

vacuum pump

21

vacuum line

25

Production unit for steam or hot water

26

Line for steam or hot water

27

jet

28

Steam or hot water jet

30

vacuum sensor

31

Infrared temperature sensor

32

Measurement line

33

Measurement line

35

controller unit

36

Infrared measuring point

40

control line

41

control line

60

scanning path

52.61

point of impact

67

direction of rotation

68

nozzles

h, h4

Stroke during one revolution of the workpiece

71

filter unit

72

Filter and separator stage

73

condensation unit

74

oil separator

75

clean tank

76

pump

77

supply line

78

bracket

Claims (14)

1. A method for cleaning the surface of a metal workpiece (4) by means of at least one jet (28) of steam and/or hot water generated by at least one nozzle (27, 68) and impinging on the surface at a point of impingement (51, 52, 61),

   - wherein during cleaning said point of impingement (51, 52, 61) of the jet (28) is moved relative to said surface in a scanning manner, wherein surface contaminants are transported in the scanning direction towards one end of the workpiece (4),

   - wherein said method is performed in a closed container (1) in a reduced pressure atmosphere, so that the residues of condensed steam or water that are present on said surface behind said point of impingement (51, 52, 61) in the scanning direction at least partially evaporate,

   - thereby at least partially extracting from said workpiece (4) the heat supplied by said jet (28), characterized in that the scanning is effected by moving said workpiece (4), said at least one nozzle (27, 68) ad/or both, and the scanning takes place by means of the jet of the nozzle (27, 68) over a scan path (50, 60), which results from superimposing a circular movement of the at least one nozzle (27, 68) and/or of the workpiece (4) and a linear movement of the workpiece (4) and/or the at least one nozzle (27, 68).
2. The method according to claim 1, characterized in that the reduced pressure in the container and the mass flow for generating the jet of steam and/or hot water is controlled so that

   - after the end of said cleaning or cleaning and drying the temperature of said workpiece (4) differs by no more than 5 K from its temperature before the start of cleaning, in particular differs by no more than 2K from the temperature before said cleaning and thereby preferably the surface of said workpiece (4) is dried behind said point of impingement (51, 52, 61) in the same process step.
3. The method according to one of the preceding claims, characterized in that several nozzles (68) are provided, each generating a jet (28) of steam and/or hot water.
4. The method according to claim 3, characterized in that said jet (28) forms an angle of between 90 and 135° with the direction of said linear movement.
5. The method according to one of the preceding claims, characterized in that water run-off or water splashes are collected in a sump (11) at the bottom of said container (1) and are pumped off through a filter unit (71), through which a negative pressure generator or a vacuum pump (20) sucks steam with contaminant residues out of said treatment chamber for generating the reduced pressure in the container (1); and/or
   in that before said cleaning or said cleaning and drying an aqueous solution of a cleaning agent is applied to said workpiece (4), preferably by spraying.
6. The method according to one of the preceding claims, characterized in that the surface temperature of said workpiece (4) behind said point of impingement (51, 52, 61), viewed in the direction of movement (6) thereof, is measured in a contactless manner and the negative pressure and the mass flow of said steam or hot water are controlled accordingly.
7. A device for cleaning the surface of a workpiece (4) through performing the method according to one of the preceding claims, comprising

   - a treatment chamber having an opening, which allows the passage of said workpiece (4) to be cleaned and which can be pressure-sealed,

   - a holder for said workpiece (4), with which it can be held within said treatment chamber and moved within said treatment chamber linearly and vertically,

   - at least one nozzle arrangement each having one or more nozzles (27, 68), wherein the workpiece (4) can be moved relative to the nozzle arrangement(s) by means of the holder and nozzle arrangement(s) comprise(s) a nozzle carrier which is rotatable relative to the holder,

   - a negative pressure generator connected to the interior of said treatment chamber for generating a negative pressure,

   - a generator unit (25) for hot water or steam under increased pressure, which is connected to said nozzle (27, 68) or said nozzles (27, 68), and

   - means for adjusting the temperature of said hot water or steam and/or means for adjusting the mass flow flowing through said nozzles.
8. The device according to claim 7, wherein said negative pressure generator is a vacuum pump (20) and said generator unit (25) is a steam generator.
9. The device according to claim 7 or 8, wherein a filter unit is provided, through which said negative pressure generator or said vacuum pump (20) sucks steam with contaminant residues out of said treatment chamber;
   wherein a further filter stage and/or separator stage (72) is attached to said filter unit (71) from which recovered cleaning fluid is fed in a closed circuit to said generator unit (25) for hot water or steam.
10. The device according to claim 7, wherein said means for adjusting the mass flow adjust the pressure of said water or steam and/or the flow resistance of the lines.
11. The device according to claim 7, wherein said nozzle arrangement comprises at least one nozzle (27, 68) rotating around an axis of rotation (7, 67) parallel to and/or at a distance from its own axis.
12. The device according to claim 7, wherein the nozzle carrier, on which several nozzles (68) of the nozzle arrangement are arranged, is rotatable around an axis of rotation (67) directed towards said workpiece (4), and wherein the nozzles (27, 68) form an angle of between 0 and 45°, preferably 0 to 15°, with the axis of rotation (67), wherein this angle can be the same or different for all the nozzles (27, 68) of this nozzle arrangement.
13. The device according to one of the preceding claims 7 to 12, further comprising means for measuring the surface temperature of said workpiece (4), in particular for contactless measuring the surface temperature of said workpiece (4), and preferably further comprising a controller unit (35) for the negative pressure and the mass flow flowing through said nozzles (27, 68) based on the measured surface temperature.
14. The device according to one of the preceding claims 7 to 13, wherein said holder (78) can be moved into and out of said treatment chamber and comprises a pressure-resistant closure for said opening of said treatment chamber.

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