EP4247570A1

EP4247570A1 - Device and method for cleaning workpieces

Info

Publication number: EP4247570A1
Application number: EP21840661.9A
Authority: EP
Inventors: Martin Ineichen
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-17
Filing date: 2021-11-17
Publication date: 2023-09-27
Also published as: WO2022106886A1

Abstract

The invention relates to a device (1) and a method for cleaning contaminated workpieces. The device contains a processing chamber (PK1, PK2, PK3), into which a workpiece to be cleaned can be introduced and which can be filled with water, which is in particular deionised, and a surfactant-containing cleaning liquid; a closure unit (VE) for opening and closing the processing chamber (PK1, PK2, PK3); and a vacuum pump (VP) which can be brought into fluidic connection with the processing chamber in order to evacuate the processing chamber (PK1, PK2, PK3). A vacuum tank (VT) is located in the fluidic connection between the vacuum pump (VP) and the processing chamber (PK1, PK2, PK3), and a first valve (V1) is located in the fluidic connection between the vacuum tank (VT) and the processing chamber (PK1, PK2, PK3). This allows a cleaning effect on the workpiece to be cleaned, both by means of the action of the cleaning liquid as a solvent and by means of the action of the cleaning liquid as a medium that transmits a pressure surge. The pressure surge is achieved by the vacuum tank (VT) first being evacuated by means of the vacuum pump (VP) and the cleaning liquid subsequently experiencing an abrupt drop in pressure as a result of the first valve (V1) being opened abruptly. An ultrasound source (US, US1, US2, US3) is preferably associated with a processing chamber (PK1, PK2, PK3). The action of the cleaning liquid as an ultrasound-transmitting medium supports the cleaning effect on the workpiece to be cleaned.

Description

Device and method for cleaning workpieces

The invention relates to a device and a method for cleaning workpieces, in particular for cleaning workpieces with a filigree or porous structure up to capillary structures, such as removing loose particles during the post-treatment of additively manufactured workpieces. The cleaning of workpieces is particularly a challenge when the workpieces have blind holes, in particular capillary blind holes.

Such devices and methods for cleaning workpieces are known, for example, from EP1338680A1 or from DE102017126329A1.

EP1338690A1 describes a method for cleaning a workpiece, in which a solvent mixture of isoparaffins is used in a first cleaning stage and deionized water with a surfactant is used in a second cleaning stage. This is followed by a rinsing step with deionized water and a final drying step. A disadvantage of this process is the use of an organic solvent.

DE102017126329A1 describes a method for cleaning a workpiece, in which the workpiece is exposed to a cleaning liquid in a cleaning chamber, which is first exposed to an overpressure and then to a negative pressure or first to a negative pressure and then to an overpressure. The alternation of positive and negative pressure is intended to achieve cavitation effects in the cleaning liquid, as a result of which impurities adhering to the workpiece are detached fluid-mechanically.

The invention has for its object to provide a device and a method for cleaning a workpiece, whereby with simple mechanical Means a cleaning of the workpiece takes place that has both fluid-mechanical effects and solvent effects.

To solve this problem, the invention provides a device for cleaning contaminated workpieces, the device having the following elements: a process chamber into which a workpiece to be cleaned can be introduced and which is at least partially filled with a cleaning liquid containing in particular deionized water and a surfactant can be filled or is filled; a shutter unit for opening and closing the process chamber; and a vacuum pump fluidly connectable to the process chamber to evacuate the process chamber; wherein, according to the invention, a vacuum tank is arranged in the fluid connection between the vacuum pump and the process chamber and a first valve is arranged in the fluid connection between the vacuum tank and the process chamber.

This enables a cleaning effect on the workpiece to be cleaned on the one hand by the action of the cleaning liquid as a solvent and on the other hand by the action of the cleaning liquid as a pressure surge-transmitting medium. The pressure surge is achieved in that the vacuum tank is first evacuated by means of the vacuum pump and then the cleaning liquid experiences a sudden drop in pressure as a result of the sudden opening of the first valve. As a result, the workpieces with filigree and capillary structures mentioned at the beginning can be cleaned effectively.

The vacuum tank volume of the vacuum tank is expediently a multiple of the process chamber volume of the process chamber. Depending on the filling level of the cleaning liquid in the process chamber, a pressure drop in the process chamber of around 1 bar (atmospheric pressure) to a small fraction of 1 bar can be achieved by opening the first valve.

The ratio VTV/PKV of vacuum tank volume VTV of the vacuum tank to process chamber volume PKV of the process chamber is preferably within a range of 5 to 200 (5<VTV/PKV<200) and particularly preferably within a range of 10 to 200 (10 < VTV/PKV < 200). As a result of this and the filling level of the cleaning liquid of, for example, more than 70% of the process chamber volume PKV of the process chamber, sudden pressure drops from around 1 bar down to less than 0.01 bar in the process chamber can be achieved by suddenly opening the first valve.

Preferably, the ratio VTV / FPKV of vacuum tank volume VTV of the vacuum tank to the free process chamber volume FPKV of the process chamber above the cleaning liquid is within 10 to 400 (10 < VTV / FPKV < 400) and preferably within 10 to 300 (10 < VTV /FPKV < 300) and most preferably within 10 to 200 (10 < VTV/FPKV < 200).

An ultrasound source can preferably be assigned to a process chamber, or an ultrasound source is assigned to a process chamber in a processing position. An ultrasound source is preferably attached to a probe which can be lowered into the process chamber filled with cleaning liquid and/or an ultrasound source is attached to the wall, preferably in the floor, of the process chamber. Both versions enable efficient introduction of ultrasonic energy into the cleaning liquid.

In a particularly preferred embodiment, a respective ultrasonic source is assigned to a respective process chamber. Each ultrasound source preferably generates a different ultrasound frequency or a different group or combination of ultrasound frequencies. In particular, ultrasonic sources are used with a crystal that is excited to oscillate, with the ultrasonic oscillation typically having a first and possibly a further harmonic with a significant amplitude in addition to the fundamental oscillation. Examples are ultrasonic sources with 25 kHz and 50 kHz or with 40 kHz, 80 kHz and 120 kHz.

A process chamber heating unit is preferably assigned to a respective process chamber.

This enables multi-stage cleaning, with the workpiece being subjected to a specific cleaning treatment in each stage. A specific ultrasonic treatment can be carried out in each stage, ie in the respective process chamber, which is characterized by the time course of the US amplitude and the US frequency as well as by the US treatment duration. Depending on the nature of the contamination, eg the size and adhesive force of the contamination particles to be removed from the workpiece or the thickness, density, viscosity etc. of grease films to be removed, US treatment that is characteristic of the respective process chamber can be particularly effective. This can be roughly described as a kind of resonance effect, in which the contamination absorbs a maximum of mechanical energy from the US wave.

In addition, a specific solvent treatment can be carried out in each stage, i.e. in the respective process chamber, which is characterized, for example, by the type and concentration of the surfactant or surfactants in the cleaning liquid, by the temperature of the cleaning liquid, etc.

For the solvent treatment, i.e. for the actual cleaning of the workpiece, it is preferable to use deionized water which contains at least one type of surfactant, typically working in the alkaline range (pH > 7).

Deionized water, which is slightly acidified (pH <7), is preferably used again for rinsing the workpiece after it has been cleaned.

In addition, a specific pressure surge treatment can be carried out in each stage, i.e. in the respective process chamber, which is determined e.g is adjustable.

A pressure surge as an explosive expansion of the air and vapor volume above the liquid surface in the process chamber is particularly effective, since such a pressure surge is a superposition of many different US frequencies, ie contains a spectrum of different US frequencies, each of which develops a special cleaning effectiveness for specific contaminants.

The process chamber, into which the workpiece to be cleaned can be introduced, preferably contains a means for moving the workpiece introduced relative to the process chamber and relative to the cleaning liquid. This allows the consequences of possible inhomogeneities in the intensity of the US wave field in the process chamber (e.g. due to constructive and destructive US interference, in particular standing US waves with amplitude antinodes and amplitude nodes) to be compensated. Should a surface area of the surface of the workpiece to be cleaned lie in a spatial region of destructive US interference with little or no cleaning effect from the ultrasonic contribution when the workpiece is in a first position within the process chamber, while moving the workpiece passes through to a second position within the process chamber, this surface area of the workpiece several spatial areas with alternating constructive and destructive interference. This ensures an ultrasonic contribution to the cleaning effect in this surface area of the workpiece.

Preferably, the apparatus includes a drying fan fluidly connectable to the processing chamber for drying the processing chamber and a cleaned workpiece contained therein.

For this purpose, a second valve can be arranged in the fluid connection containing the drying fan and the process chamber, with which a fluid path for drying can be opened.

Preferably, an air (HEPA) filter is provided upstream of the drying fan, i.e., on the atmosphere side, to filter contaminants from the ambient air and prevent contamination of the cleaned workpiece.

Preferably, a drying air heating unit is provided downstream of the drying fan to accelerate the volatilization of residual water (the rinsing liquid) from the workpiece. In a particularly preferred embodiment, the device contains a plurality of process chambers, in particular at least three process chambers. As mentioned above, this enables a multi-stage cleaning of the workpiece with a specific cleaning treatment in each stage or process chamber.

The device preferably contains a positioning unit on which the multiple process chambers are fixed next to one another, the positioning unit being able to position one of the process chambers in a processing position within the device.

In a first embodiment, the positioning unit is a turret assembly rotatable about an axis to provide a selected process chamber with its specific US source, cleaning liquid, fill level, etc. for receiving a workpiece to be cleaned can.

In a second embodiment, the positioning unit is a sliding bar arrangement that can be translocated along an axis, so that here too a selected process chamber with its specific US source, its specific cleaning liquid, its specific filling level, etc. for receiving a workpiece to be cleaned can be provided.

The device preferably contains a receiving unit for a workpiece to be cleaned, the receiving unit being movable relative to a process chamber. As a result, the receiving unit can be moved into a selected process chamber. The receiving unit can be designed as a cage or as a basket. The device expediently contains a cage which can be moved relative to a process chamber and in which a basket can be fastened, into which one or more workpieces to be cleaned can be placed.

The device preferably contains a translation unit, by means of which the receiving unit can be moved into and out of a process chamber. A shielding means can preferably be arranged within a process chamber a) in the region of an upper interface between the cleaning liquid and a free process chamber volume above the cleaning liquid, or b) within the free process chamber volume above the cleaning liquid. As a result, on the one hand foam, droplets or splashes of cleaning liquid can be intercepted during the abrupt evacuation of the free process chamber volume, which could otherwise get into the fluid connection between the vacuum pump and the process chamber. If cleaning liquid gets into this fluid connection and thus into the vacuum tank, the vapor pressure of the cleaning liquid makes it difficult to evacuate the vacuum tank, thereby slowing down the process. On the other hand, the evaporation of cleaning agent into the free, ie liquid-free, process chamber volume above the cleaning liquid is reduced by the shielding means. The cleaning liquid vapor pressure, which contributes to the total pressure in the free process chamber volume, therefore builds up much more slowly than without shielding means. This contributes to the fact that the sudden drop in pressure mentioned at the outset is particularly large and occurs particularly quickly.

The shielding means can be mounted floating on the cleaning liquid or mounted within the free process chamber volume above the cleaning liquid. In both cases, at least a large part of the foam, the droplets or the splashes of cleaning liquid can be intercepted when the free volume of the process chamber is suddenly evacuated.

Alternatively, the shielding means may be stored inside the cleaning liquid below the upper boundary. This measure also reduces the formation of foam, droplets or splashes of cleaning liquid when the free process chamber volume is suddenly evacuated, which could otherwise get into the fluid connection between the vacuum pump and the process chamber.

For this purpose, the upward-facing surface of the

Shielding means or the top portions of the shielding means Penetration depth from 0 mm to 30 mm below the upper boundary surface of the cleaning liquid.

The shielding means can have an opening above which a screen is arranged. A large part of the foam, the droplets or the splashes of cleaning liquid can be intercepted when the free volume of the process chamber is suddenly evacuated.

In a first variant, the shielding means contains an air-permeable porous layer which preferably covers 70% to 100% and particularly preferably 85% to 98% of the surface of the cleaning liquid and forms a type of cover or screen.

There is preferably play or a gap between the edges of the cover and the inner boundary surfaces or inner surfaces of the process chamber. This play or gap prevents the cover or screen from getting stuck inside the process chamber. This ensures that the cover or screen can be easily removed from the process chamber or that the cover or screen can be pivoted within the process chamber before the process chamber is filled with cleaning liquid.

Above all, this makes it easier to dry the cleaned workpiece in a hot, dry gas stream that is passed through the process chamber. In addition, filling the process chamber with cleaning liquid is made easier if this filling is to take place from above.

However, the process chamber is preferably filled with cleaning liquid from below.

The gap preferably has a width in the range from 1 mm to 7 mm, particularly preferably in the range from 2 mm to 5 mm. This is a good compromise between adequate shielding and good mobility of the cover or screen.

The air-permeable, porous layer preferably contains a large number of fibers arranged one on top of the other, in particular in the form of a textile structure, such as a woven fabric, a fleece, a felt or the like. The shielding means preferably contains a large number of bulk material bodies as a bulk material layer or as a bulk material pack, the density of the bulk material bodies being less than the density of the cleaning liquid. As a result, the bulk goods float on the surface of the cleaning liquid. Depending on the number of bulk material bodies, several layers of bulk material bodies form on the surface of the cleaning liquid.

The bulk material bodies can also be present as a sinter plate or as a sinter block made of bulk material bodies that are glued or melted together.

In a second variant, the shielding means contains an air-impermeable layer or barrier layer, i.e. a layer which, in particular, does not allow the molecules of water vapor and the other molecules in the air (nitrogen, oxygen, carbon dioxide, argon) to pass through, with this layer preferably having 70% to 98% and more preferably 85% to 98% of the surface of the cleaning liquid is covered and forms a kind of lid or screen, and the density of the layer is lower than the density of the cleaning liquid. As a result, the layer floats on the surface of the cleaning liquid. Depending on the thickness of the layer, it sinks more or less deeply into the cleaning liquid.

There is play or a gap between the radially outer edges of the cover and the inner boundary surfaces or inner surfaces of the process chamber. In the area of this gap, the phase boundary between the cleaning liquid and its vapor is open, and it is only there that molecules of the cleaning liquid, in particular water molecules, can pass from the liquid phase to the vapor phase or vice versa. Since a large part of the surface of the cleaning liquid is covered by the barrier layer in a gas-tight (particularly air-tight) and vapor-tight (particularly water-vapour-tight) manner, the area of the liquid/vapour phase boundary and thus the evaporation rate (mass of evaporated liquid per unit of time) is greatly reduced. As explained above, this causes the sudden drop in pressure to become greater and faster. In addition, this play or this gap also prevents the cover or screen from becoming jammed inside the process chamber. This ensures that the cover or screen can be easily removed from the process chamber or that the cover or screen can be pivoted within the process chamber before the process chamber is filled with cleaning liquid.

Here, too, the gap, i.e. the radially outer gap, preferably has a width in the range from 1 mm to 7 mm, particularly preferably in the range from 2 mm to 5 mm. This is a good compromise between 1) adequate liquid-vapor phase communication, 2) adequate shielding against foam, droplets, and splashes, and 3) good mobility of the lid or screen.

Preferably, there is also a clearance or gap between the radially inner lid edges and inner surfaces of the process chamber, such as a rotation axis of the rotation unit.

This gap, i.e. the radially inner gap, preferably has a width in the range from 0.1 mm to 0.3 mm, particularly preferably in the range from 0.1 mm to 0.2 mm. This allows the lid to be rotated for the spinning step described below.

Combinations of the variants described in the preceding 13 paragraphs can also be used as shielding means. Such combinations can on the one hand be used to shield foam, droplets or splashes of the cleaning liquid and on the other hand to adjust the extent of the vapor barrier.

The device preferably contains a rotation unit, by means of which the receiving unit and/or the shielding means can be rotated about an axis within a process chamber, with the rotation axis of the rotation unit (RE) in particular coinciding with the translation axis of the translation unit (TE). As a result, both the recording unit and the shielding means can be thrown to avoid during various process steps to minimize carry-over of cleaning liquid.

The vacuum tank is expediently assembled from several vacuum tank components and can be reversibly disassembled, the assembled vacuum tank having sealing means at least in contact areas of the vacuum tank wall sections of adjacent vacuum tank components, which are clamped between adjacent vacuum tank components. By disassembling the vacuum tank, its interior, particularly the surfaces of its inner walls, can be cleaned.

The device expediently contains a control unit, by means of which at least one of the following elements can be controlled: first valve, second valve, closure unit, vacuum pump, ultrasound source, drying fan, positioning unit, translation unit, rotation unit, heating unit for drying air, heating unit for the process chamber, valves for filling and emptying of the process chambers, dosing units for surfactant admixture.

The device expediently contains at least one filling level measuring unit. This can be a US echo sounder sensor.

The filling level measuring unit can be arranged in the upper area of the process chamber.

The device expediently contains at least one temperature measuring unit for measuring the process chamber temperature and/or the drying temperature. The temperature measuring unit is preferably attached to the recording unit.

The device expediently contains a conductivity measuring unit for measuring the conductivity of the cleaning liquid, in particular for measuring the conductivity of the rinsing liquid (last cleaning step). The conductivity measuring unit is preferably attached to the recording unit. Preferably, the receiving unit is attached to a probe which can be translated up and down to lower the receiving unit into the cleaning liquid of a process chamber and which can be reciprocated rotationally or rotationally moved in one direction to prevent spinning/ To effect centrifugation of a cleaned workpiece.

The probe can be equipped with the above and other measuring units.

The device expediently contains a closure unit. The closure unit is preferably attached to the probe.

Alternatively, the closure unit can be formed by a first formation arranged on the receiving unit and by a second formation arranged on the process chamber, which is complementary to the first formation.

Preferably, the first formation is located on an underside of the receiving unit and the second formation is located on an upper side of the process chamber, at least one of the formations having a sealing means such as an elastomeric rim, an O-ring or the like.

As a result, when the receiving unit is lowered into the process chamber, not only is the workpiece to be cleaned immersed in the cleaning liquid, but the process chamber is also hermetically sealed.

The device expediently contains a pressure sensor in the vacuum tank.

The device expediently contains a pressure sensor which can be assigned to the active one in the process chamber.

The pressure sensor is preferably assigned to the control unit in such a way that the latter suddenly opens the first valve when the pressure sensor detects that the pressure in the vacuum tank has fallen below a predetermined level. The device expediently contains a foam sensor arranged in the fluid connection between the process chamber and the first valve. The foam sensor is preferably assigned to the control unit in such a way that it closes the first valve abruptly when the foam sensor detects foam.

In order to achieve the object mentioned at the outset, the invention also provides a method for cleaning contaminated workpieces, in particular using a device described above, the method having the following steps: a) introducing a contaminated workpiece into a receiving unit; b) introducing the receiving unit with the contaminated workpiece into a process chamber; c) filling the process chamber with a cleaning liquid up to a filling level which corresponds to a partial filling of the process chamber with cleaning liquid; d) hermetically closing the process chamber by means of a closing unit, which is attached in particular to the receiving unit; e) evacuating a vacuum tank by means of a vacuum pump; f1) Establishing a first fluid connection between a location above the filling level of the process chamber filled with cleaning liquid and the vacuum tank by opening a first valve; g1) blocking the first fluid connection by closing the first valve; f2) establishing a second fluid connection between a location above the filling level of the process chamber filled with cleaning liquid and the atmosphere by opening a second valve; g2) blocking the second fluid connection by closing the second valve; h) removing cleaning liquid from the process chamber and from the cleaned workpiece; i) opening the process chamber by means of the closure unit; j) removing the receiving unit with the cleaned workpiece from the process chamber; k) removing the cleaned workpiece from the receiving unit. Steps a), b) and c) of the process can be carried out in any order.

Step c) of filling the process chamber can take place after or before step b) of inserting the receiving unit.

Alternatively, step c) of filling the process chamber can also take place after or before step a) of inserting the receiving unit.

Preferably, after opening the first valve in step f1), the first valve is closed in step g2) before more than 1/10, preferably more than 1/100, of the volume of the cleaning liquid has passed through the first valve.

The closing of the first valve can be triggered by the foam sensor.

Alternatively, the closing of the first valve can also be triggered without a foam sensor by keeping the first valve open for a sufficiently short time between steps f1) and g1). Conveniently the first valve is held open for a period of less than 250 ms, preferably less than 100 ms, more preferably for a period of less than 50 ms and most preferably for a period of less than 30 ms.

During at least one of steps c) to h), ultrasound is preferably introduced into the cleaning liquid from an ultrasound source. This results in a superimposition of US treatment on the one hand and solvent treatment and/or pressure surge treatment on the other hand, which increases the cleaning effect.

Preferably, even before step f1), ultrasound is introduced into the cleaning liquid from an ultrasound source. This achieves degassing of the cleaning liquid, ie some of the gases dissolved in it (eg oxygen, nitrogen, carbon dioxide) are expelled from the cleaning liquid. This in turn reduces the occurrence of foam, droplets or splashes of cleaning liquid when the free process chamber volume is suddenly evacuated. The introduction of the ultrasound into the cleaning liquid preferably takes place over a period of 1 minute to 5 minutes, particularly preferably over a period of 2 minutes to 3 minutes.

During at least one of steps c) to h), the introduced workpiece is preferably moved relative to the process chamber and relative to the cleaning liquid. As a result, the consequences of any inhomogeneities in the intensity of the US wave field in the process chamber can be compensated for, as a result of which a more even ultrasound contribution to the cleaning effect is ensured over all surface areas of the workpiece.

The removal of cleaning liquid from the process chamber and from the cleaned workpiece in step h) preferably includes a rotation of the receiving unit with the cleaned workpiece, the receiving unit being rotated about an axis of rotation by means of a rotation unit. This causes the workpiece to be spun/centrifuged, which on the one hand enables pre-drying of the workpiece and on the other hand minimizes carryover of cleaning liquid between the individual steps of the cleaning process.

The removal of cleaning liquid from the process chamber and from the cleaned workpiece in step h) preferably includes drying the cleaned workpiece in the process chamber by means of a drying fan. A heating unit for heating the drying air is preferably connected downstream of the drying fan.

According to a particularly advantageous embodiment of the method, the sequence of steps e), f1), g1), f2) and g2) is repeated several times in one of the process chambers.

This saves all previous steps (before step e) and all subsequent steps (after step g2). Depending on the filling level of the cleaning liquid in the process chamber, the multiple repetition of steps e), f1), g1), f2) and g2) does not lead to any further contamination worth mentioning of the cleaning liquid and thus no significant impairment of the cleaning effect in the repeated sequences of steps e), f1), g1), f2), g2).

A variant of the method is particularly preferred in which step e) of evacuation lasts permanently, while the sequence of steps f1), g1), f2) and g2) is run through several times in one of the process chambers. This causes multiple, consecutive pressure surges in the respective process chamber.

Step f2) for establishing the second fluid connection between the location above the filling level of the process chamber filled with cleaning liquid and the atmosphere by opening the second valve causes the vacuum in the respective process chamber to be broken, which was required during the cleaning steps of the workpiece. After this step f2), the further steps h) to k) and drying, in particular vacuum drying, of the workpiece can take place.

Preferably, the vacuum breaking is sufficiently slow, within 1 to 20 seconds, to prevent an impact from a spring force of a seal.

According to a further particularly advantageous embodiment of the method, the sequence of steps b) to j) is run through several times and in each case in different process chambers.

This enables the multi-stage cleaning described above, with the workpiece being subjected to a specific cleaning treatment in each stage or in each process chamber.

According to yet another particularly advantageous embodiment of the method, after the cleaned workpiece has been dried and heated, steps e) and f1) are carried out again in a process chamber that is preferably only filled with air, i.e. freed of cleaning liquid and rinsing liquid.

Here, too, the sequence of steps f1), g1), f2) and g2) is preferably repeated several times. As a result, residues of cleaning liquid and residues of impurities, which are still located in particularly filigree or even capillary cavities of the workpiece, can be expelled explosively into the process chamber freed from cleaning liquid or rinsing liquid.

In a particularly preferred embodiment of the method, when the first fluid connection is established by opening the first valve in step f1), a pressure drop Ap from an initial pressure p1 to an end pressure p2 takes place at the location above the filling level of the process chamber filled with cleaning liquid for a period of time At, where the initial pressure p1 is between 0.9 bar and 1.1 bar (0.9 bar < p1 < 1.1 bar), the final pressure p2 is between 0.01 bar and 0.3 bar (0.01 bar < p2 < 0.3 bar), and the time At is in the range from 50 ms to 200 ms (50 ms < At < 200 ms).

Preferably the cleaning liquid has a temperature in the range of 10°C to 70°C and preferably in the range of 20°C to 50°C.

Further advantages, features and possible applications of the invention result from the following description of exemplary embodiments of the invention, which are not to be regarded as limiting, with reference to the drawing, in which:

1 shows a first perspective view of a first embodiment of the device according to the invention;

Fig. 2 shows the perspective view of the first embodiment of the device according to the invention in a partially cut-away state;

Fig. 3 shows a second perspective view of the first embodiment of the device according to the invention in a partially cut-away condition;

Fig. 4 shows a third perspective view of the first embodiment of the device according to the invention in a partially cut-away state; Fig. 5 shows a perspective view of a first assembly shown in Fig. 2, Fig. 3 and Fig. 4 of the first embodiment of the device according to the invention;

Figure 6 shows a perspective view of a second assembly shown in Figures 3 and 4 of the first embodiment of the device according to the invention;

7 shows a perspective view of a partially cut-open process chamber of a second embodiment of the device according to the invention;

8 shows a side view of the partially cut-open process chamber of the second embodiment of the device according to the invention;

9 shows a perspective view of a partially sectioned process chamber of a third embodiment of the device according to the invention; and

10 shows a side view of the partially sectioned process chamber of the third embodiment of the device according to the invention.

In Fig. 1 is a first perspective view of a first embodiment of the device 1 is shown. A cabinet-like or box-like housing GV of the device can be seen. The housing GV has an essentially rectangular plan. It has four wheels R on its underside, which are each arranged in the area of a corner of the base area of the housing GV. On a side wall (front wall), the housing GV has a control panel BF, on which process parameters can be set or measured process parameters can be read. On the same side wall (front wall), the housing GV also has two access doors ZT, which allow access to the actual process chambers PK1, PK2, PK3 (see Fig. 2) and other process chambers (not shown in Fig. 2), in which workpieces ( not shown) can be cleaned.

In Fig. 2 the perspective view of the first embodiment of the device 1 is shown in a partially cut-away state (part of the front wall of the housing GV removed). You can see three process chambers PK1, PK2, PK3, which are attached to a positioning unit PE between a positioning unit upper part PEO and a positioning unit base PEU are attached. Three further process chambers in the positioning unit PE are covered and therefore not shown. The positioning unit PE can be rotated about a vertical axis of rotation, so that each of the six process chambers can be brought into a processing position. In the state shown in FIG. 2, the process chamber PK2 is in its processing position.

A receiving unit AE, in which a workpiece (not shown) to be cleaned can be positioned, is arranged above the positioning unit PE with the six process chambers PK1, PK2, PK3 (and three others). The receiving unit AE is in the form of a cage into which, for example, a basket (not shown) containing one or more workpieces to be cleaned can be inserted. The recording unit AE is attached to the lower end of a translation unit TE and a rotation unit RE.

By means of the translation unit TE, the receiving unit AE can be lowered along a translation axis into the process chamber PK2 arranged underneath, which is in its processing position, after or before the process chamber PK2 is filled with cleaning liquid.

The receiving unit AE lowered into the process chamber PK2 can be rotated about a vertical axis of rotation, which coincides with the axis of translation, by means of the rotation unit RE. This rotation can be used for spinning/centrifuging the receiving unit AE in the process chamber PK2 in order to achieve pre-drying of workpieces positioned in the receiving unit AE. 2 also shows an assembly 2 which contains a first valve V1 and a second valve V2. The assembly 2 is shown in more detail in FIG. The first valve V1 is connected to a vacuum source in the form of a vacuum tank VT (see FIG. 3) via a first hose line SL1 shown in dashed lines. The second valve V2 is connected to the atmosphere via a second hose line SL2 shown in dashed lines.

A heating unit HK for heating the respective process chamber is attached to each of the two process chambers PK1 and PK2. Preferably the Heating unit HK is a resistive heating foil, which is embedded in the wall of the respective process chamber.

An ultrasound source US1 or US2 is installed in the base of each of the two process chambers PK1 and PK2.

In Fig. 3 there is shown a second perspective view of the first embodiment of the device 1 in a partially cut-away state (a part of the front wall and the left side wall of the housing GV removed). As in FIG. 2, the recording unit AE arranged above the process chamber PK2 can be seen. The hose lines SL1 and SL2 shown in dashed lines can also be seen.

The process chamber PK2 can also be seen, to which the heating unit HK for heating the process chamber is attached.

It can also be seen that an ultrasound source US2 is fitted in the bottom of the process chamber PK2.

4 shows a third perspective view of the first embodiment of the device 1 in a partially cut-away state (entire front wall and entire right-hand side wall of the housing GV removed). You can see the process chambers PK2, PK3 and PK4. The process chamber PK2 is located below the receiving unit AE in its processing position. The closure unit VE arranged on the assembly group 2 can also be seen, with which the upper opening of the process chamber PK2 located in its processing position can be hermetically sealed.

A vacuum pump VP, which is used to evacuate the vacuum tank VT, can be seen in the lower part of the device 1 . The vacuum pump VP is connected to the vacuum tank VT via its connection pipe A2", a third hose line SL3 shown in dashed lines, a vacuum pipe VR and a fourth hose line SL4 shown in dashed lines to the vacuum tank VT. The vacuum pump VP can be operated permanently in order to provide a permanent vacuum in the vacuum tank VT. When the first valve V1 is opened, the vacuum of the vacuum tank VT sucks air out of the Process chamber PK2, which also creates a vacuum in the process chamber PK2. Since the volume of the vacuum tank VT is much larger than the liquid-free volume of the process chamber PK2 above the filling level of the cleaning liquid, a sudden drop in pressure can be generated in the process chamber PK2 and in the cleaning liquid contained therein by opening the first valve V1. By alternately opening and closing the first valve V1 and alternately opening and closing the second valve V2, i.e. the repeated sequence of steps f1), g1), f2), g2), with permanent operation of the vacuum pump VP, numerous successive pressure drops or Pressure surges can be achieved in the process chamber PK2.

Also visible in the lower part of the device 1 is a drying fan TV with an upstream air filter LF for the drying air and a downstream heating unit HE for the drying air. The process chamber PK2, which is in its processing position, is connected downstream of the heating unit HE in the drying air line. When the second valve is open, the drying fan TV forces drying air through the process chamber PK2 and into the atmosphere via the second hose line SL2.

The heating unit HK for heating the respective process chamber is attached to the two process chambers PK2 and PK4.

An ultrasound source US2 or US4 is installed in the base of each of the two process chambers PK2 and PK4.

FIG. 5 shows a perspective view of a first subassembly 2 of the first embodiment of the device 1 shown in FIGS. 2, 3 and 4 . The assembly 2 contains the first valve V1 and the second valve V2. On the first valve V1 there is a connecting pipe AT to which the first hose line SL1 is connected (see FIG. 2, FIG. 3, FIG. 4). On the second valve V2 there is a connecting tube A2' to which the second hose line SL2 is connected (see FIGS. 2, 3, 4). The assembly 2 also contains a closure unit VE, with which the upper opening of the process chamber PK2 can be hermetically sealed. A foam sensor SS is arranged in the channel that is then formed between the first valve V1 and the process chamber PK2. If the opening of the first valve V1 causes (excessive) foaming of the cleaning liquid in the process chamber PK2, for example because its temperature is too high and/or because the liquid level in the process chamber PK2 is too high, for example, cleaning liquid could be sucked into the vacuum tank VT will. This must be prevented so that the vacuum drawn by the vacuum pump VP in the vacuum tank VT is not destroyed by vapors (eg water vapor) from the cleaning liquid. If the foam sensor SS detects foam in the channel, this signal can be used via a control unit to immediately close the first valve V1.

In addition or as an alternative to the foam sensor SS, the first valve V1 can be controlled in such a way that it opens as quickly as possible ("suddenly") and closes as quickly as possible ("suddenly") after a short time in the open state. This can also prevent cleaning liquid from being sucked into the vacuum tank VT as foam.

The assembly 2 also contains a pressure sensor DS for detecting the pressure in the respective process chamber, which is located under the assembly 2 in its processing position (process chamber PK2 in FIG. 2, FIG. 3, FIG. 4). The pressure sensor DS is located on the underside of the closure unit VE and is therefore not visible in FIG.

The assembly 2 also contains an ultrasound source US for introducing ultrasound into the respective process chamber, which is located under the assembly 2 in its processing position (process chamber PK2 in FIG. 2, FIG. 3, FIG. 4). The ultrasound source US is located on the underside of the closure unit VE and is therefore not visible in FIG.

The ultrasound source US thus represents an additional ultrasound source in addition to the ultrasound sources US1, US2, US3, etc. specific to a process chamber PK1, PK2, PK3, etc. FIG. 6 shows a perspective view of a second assembly shown in FIGS. 3 and 4 of the first embodiment of the device 1 . This second assembly forms the vacuum tank VT. It is connected to the process chamber PK2 via its connecting pipe A1, the first hose line SL1 (see FIGS. 2, 3, 4) and the connecting pipe AT of the first valve 1 (see FIG. 5). In addition, the vacuum tank VT is connected to the vacuum pump VP via its connection pipe A2, the fourth hose line SL4, the vacuum pipe VR, the third hose line SL3 (see FIG. 4) and the connection pipe A2".

It can also be seen that the cuboid housing GT of the vacuum tank VT is stabilized by means of a perforated reinforcement plate VPT and numerous reinforcement supports VST. The stiffening plate VPT extends parallel between two opposite large surfaces of the housing GT. The stiffening plate VPT extends from a first small area to a second small area of two opposite pairs of small areas (pairs of end faces) of the housing GT. The stiffening supports VST extend through the holes in the perforated stiffening plate VPT parallel to the small surfaces (front surfaces) and orthogonally to the two large surfaces.

FIG. 7 shows a perspective view of a partially cut open process chamber PK of a second embodiment of the device 1 . The process chamber PK is partially filled with a cleaning liquid RF, e.g. water with surfactant. The receiving unit AE is immersed in the cleaning liquid RF. A basket (not shown), for example, which contains one or more workpieces (not shown) to be cleaned, can be inserted into the cage-like receiving unit AE. The receiving unit AE is attached to the lower end of a combined translation/rotation unit TE/RE, by means of which the receiving unit AE together with the workpieces it contains can be moved linearly up and down along a vertical axis and rotated back and forth around this vertical axis can be.

A shielding means SM, which is present here in the form of a plate or mat P/M, floats on the upper surface of the cleaning liquid RF. whose density is lower than the density of the cleaning liquid RF. The plate or mat P/M is sized to cover most of the top surface of the cleaning fluid RF. The process chamber PK can have any shape. There is a gap AS and IS between the edges of the plate or mat P/M and the inner boundary surfaces of the process chamber PK, which prevents the plate or mat P/M from getting stuck inside the process chamber PK. This ensures easy removal of the plate or mat P/M from the process chamber PK or pivoting of the plate or mat P/M within the process chamber PK before it is filled with cleaning liquid RF.

Preferably, as shown in FIG. 7, the process chamber PK is cylindrical. The plate or mat P/M surrounding the unit of translation/rotation TE/RE therefore has the shape of an annulus. There is therefore an inner gap IS between the inner edge of the plate or mat P/M and the translation/rotation unit TE/RE and an outer gap AS between the outer edge of the plate or mat P/M and the inner lateral surface of the cylindrical process chamber PK. The inner gap IS and the outer gap AS each have a gap width in the range from 1 mm to 7 mm, which ensures both an adequate shielding effect and good mobility of the plate or mat P/M.

FIG. 8 shows a side view of the partially cut open process chamber PK of the second embodiment of the device 1 . The cleaning liquid RF can be seen in the lower area of the process chamber PK, the receiving unit AE immersed therein and the shielding means SM in the form of the plate or mat P/M. You can also see the inner gap IS between the plate or mat P/M and the translation/rotation unit TE/RE and the outer gap AS between the plate or mat P/M and the inner lateral surface of the cylindrical process chamber PK.

FIG. 9 shows a perspective view of a partially cut open process chamber PK of a third embodiment of the device 1 . The third embodiment differs from the second embodiment only in that the shielding means SM instead of a floating plate or mat P/M is a A large number of bulk bodies SK are provided as a bulk material layer or as a bulk material pack, the density of the bulk bodies SK being smaller than the density of the cleaning liquid RF, so that the bulk bodies SK float on the surface of the cleaning liquid RF. Depending on the number and size of the bulk goods SK, several layers of bulk goods SK can pile up on the surface of the cleaning liquid RF. The bulk solids SK are rounded bodies in the form of spheres, pellets, etc.

The bulk goods SK can be in the form of loose bulk or packing. Alternatively, they can be present as a sintered plate or as a sintered block made of bulk material bodies SK that are glued together or melted together.

Preferably, as shown in FIG. 9, the process chamber PK is cylindrical. The loose bed or the sintered block of bulk bodies SK surrounds the translation unit/rotation unit TE/RE and therefore has approximately the shape of a circular ring.

FIG. 10 shows a side view of the partially cut open process chamber PK of the third embodiment of the device 1 . You can see the cleaning liquid RF in the lower area of the process chamber PK, the receiving unit AE immersed in it and the shielding means SM in the form of several layers of bulk material bodies SK, which pile up between the translation unit/rotation unit TE/RE and the inner lateral surface of the cylindrical process chamber PK .

Reference List

1 device for cleaning

2 valve assembly

GV casing of the device

BF control panel

ZT access door

R wheel

PK process chamber

PK1 first process chamber

PK2 second process chamber

PK3 third process chamber

PK4 fourth process chamber

RF cleaning fluid

VE locking unit

VP vacuum pump

VT vacuum tank

GT housing of the tank

VPT tank stiffening plate

VST stiffening support of the tank

A1 Connection pipe (of the vacuum tank) for process chamber connection

A2 Connection pipe (of the vacuum tank) for vacuum pump connection

A1 ' Connection pipe (of the valve assembly) for vacuum tank connection

A2' Connection pipe (of valve assembly) for exhaust connection to atmosphere

A2" connection pipe (of the vacuum pump) for process chamber connection

V1 first valve (between vacuum tank and process chamber)

V2 second valve (between vacuum tank and atmosphere)

VTV vacuum tank volume

PKV Process Chamber Volume

AE receiving unit for the workpiece to be cleaned

DS pressure sensor for process chamber pressure

US ultrasound source

US1 first ultrasonic source (at first process chamber)

US2 second ultrasonic source (on second process chamber)

US3 third ultrasonic source (on third process chamber)

US4 fourth ultrasonic source (at fourth process chamber)

PE positioning unit

PEO positioning unit top

PEU positioning unit lower part

LF air filter (for drying air)

HE heating unit (for drying air)

HK heating unit (for process chamber)

TV drying fan

TE translation unit (for recording unit)

RE rotation unit (for recording unit)

SM shielding agent

P/M plate or mat

SK bulk body

IS inner gap AS outer gap

SS foam sensor

SL1 first hose line

SL2 second hose line

SL3 third hose line

SL4 fourth hose line

VR vacuum tube

Claims

Expectations

1. Device (1) for cleaning contaminated workpieces, the device having: a process chamber (PK1, PK2, PK3), into which a workpiece to be cleaned can be introduced and which is filled with a cleaning liquid (RF ) is at least partially fillable or filled; a closure unit (VE) for opening and closing the process chamber (PK1, PK2, PK3); and a vacuum pump (VP) fluidly connectable to the process chamber for evacuating the process chamber (PK1, PK2, PK3); characterized in that a vacuum tank (VT) is arranged in the fluid connection between the vacuum pump (VP) and the process chamber (PK1, PK2, PK3) and in the fluid connection between the vacuum tank (VT) and the process chamber (PK1, PK2, PK3) a first valve (V1) is arranged.

2. Device according to claim 1, characterized in that the vacuum tank volume (VTV) of the vacuum tank (VT) is a multiple of the process chamber volume (PKV) of the process chamber (PK1, PK2, PK3).

3. Device according to claim 2, characterized in that the ratio VTV/PKV of the vacuum tank volume (VTV) of the vacuum tank (VT) to the process chamber volume (PKV) of the process chamber (PK1, PK2, PK3) is within a range of 5 to 200 (5 < VTV/PKV < 200), and preferably within a range of 10 to 200 (10 < VTV/PKV < 200).

4. Device according to claim 2 or 3, characterized in that the ratio VTV / FPKV of the vacuum tank volume (VTV) of the vacuum tank (VT) to the free process chamber volume (FPKV) of the process chamber (PK1, PK2, PK3)

28 above the cleaning liquid (RF) is within a range of 10 to 400 (10 < VTV/FPKV < 400) and preferably within a range of 10 to 300 (10 < VTV/FPKV < 300) and most preferably in the range of 10 to 200 (10 < VTV/FPKV < 200).

5. Device according to one of Claims 1 to 4, characterized in that an ultrasound source (US, US1, US2, US3) can be assigned to a process chamber (PK1, PK2, PK3), or that a process chamber (PK1, PK2, PK3) in an ultrasound source (US, US1, US2, US3) is assigned to a processing position.

6. The device according to claim 5, characterized in that a respective ultrasonic source (US1, US2, US3) is assigned to a respective process chamber (PK1, PK2, PK3), each ultrasonic source preferably having a different ultrasonic frequency or a different group or combination generated by ultrasonic frequencies.

7. Device according to one of claims 1 to 6, characterized in that the process chamber (PK1, PK2, PK3), into which the workpiece to be cleaned can be introduced, a means for moving the workpiece introduced relative to the process chamber and relative to the cleaning liquid ( RF).

8. Device according to one of claims 1 to 7, characterized in that the device has a drying fan (TV) which can be brought into fluid connection with the process chamber for drying the process chamber (PK1, PK2, PK3) and a cleaned workpiece contained therein .

9. The device according to claim 8, characterized in that a second valve (V2) is arranged in the fluid connection containing the drying fan (TV) and the process chamber (PK1, PK2, PK3), with an air filter (LV) preferably being installed upstream of the drying fan (TV) is arranged and preferably a heating unit (HE) for the drying air is arranged downstream of the drying fan (TV).

10. Device according to one of claims 1 to 9, characterized in that the device has a plurality of process chambers (PK1, PK2, PK3), in particular at least three process chambers.

11. The device as claimed in claim 10, characterized in that the device has a positioning unit (PE) on which the plurality of process chambers (PK1, PK2, PK3) are fixed next to one another, the positioning unit being able to position one of the process chambers in a processing position within the device . (-> rotation, translation)

12. Device according to one of claims 1 to 11, characterized in that the device has a receiving unit (AE) for a workpiece to be cleaned, wherein the receiving unit (AE) is movable relative to a process chamber (PK1, PK2, PK3). (-> cage and/or basket)

13. Device according to claim 12, characterized in that the device has a translation unit (TE) by means of which the receiving unit (AE) can be moved into and out of a process chamber (PK1, PK2, PK3).

14. Device according to one of claims 1 to 13, characterized in that within a process chamber (PK1, PK2, PK3) a) in the area of an upper boundary surface, which is between the cleaning liquid (RF) and a free process chamber volume (FPKV) located above the cleaning liquid (RF), or b) a shielding means (SM) can be arranged or is arranged within the free process chamber volume (FPKV) above the cleaning liquid (RF).

15. Device according to claim 14, characterized in that the shielding means (SM) is mounted floating on the cleaning liquid (RF) or is mounted within the free process chamber volume (FPKV) above the cleaning liquid (RF).

16. Device according to claim 14, characterized in that the shielding means (SM) is mounted inside the cleaning liquid (RF) below the upper boundary surface.

17. Device according to claim 16, characterized in that the upwardly facing surface of the shielding means (SM) or the uppermost areas of the shielding means (SM) have a penetration depth of 0 mm to 30 mm below the upper boundary surface of the cleaning liquid (RF).

18. Device according to one of claims 14 to 17, characterized in that the shielding means (SM) has an opening above which a screen is arranged.

19. Device according to one of claims 14 to 18, characterized in that the shielding means (SM) has an air-permeable porous layer which preferably covers 70% to 100% and particularly preferably 85% to 98% of the surface of the cleaning liquid.

20. The device according to claim 19, characterized in that the air-permeable, porous layer has a large number of fibers arranged one on top of the other, in particular in the form of a textile structure, such as a woven fabric, a fleece, a felt or the like.

21. Device according to claim 19 or 20, characterized in that the shielding means (SM) has a large number of bulk material bodies (SK) as a bulk material layer or bulk material pack, the density of the bulk material bodies being less than the density of the cleaning liquid (RF) is.

22. Device according to claim 21, characterized in that the bulk material bodies (SK) are present as a sintered plate or as a sintered block of bulk material bodies which are glued together or melted together.

23. Device according to one of claims 14 to 22, characterized in that the shielding means (SM) has an air-impermeable layer which preferably 70% to 98% and more preferably 85% to 98% of the surface of the cleaning liquid is covered, and the density of the layer is less than the density of the cleaning liquid (RF).

24. Device according to one of claims 12 to 23, characterized in that the device has a rotation unit (RE) by means of which the receiving unit (AE) and/or the shielding means (SM) are rotated within a process chamber (PK1, PK2, PK3). an axis can be rotated, in particular the axis of rotation of the rotation unit (RE) coincides with the translation axis of the translation unit (TE).

25. Device according to one of claims 1 to 24, characterized in that the vacuum tank (VT) is assembled from several vacuum tank components and can be reversibly disassembled, the assembled vacuum tank (VT) at least in contact areas of the vacuum tank wall sections of adjacent vacuum tank Components having sealing means sandwiched between adjacent vacuum tank components.

26. Device according to one of claims 1 to 25, characterized in that the device has a control unit, by means of which at least one of the following elements can be controlled:

- first valve (V1)

- second valve (V2)

- locking unit (PU)

- vacuum pump (VP)

- Ultrasonic source (US, US1 , US2, US3) - Drying fan (TV)

- positioning unit (PE)

- translation unit (TE)

- rotation unit (RE)

- Heating unit (HE) for drying air

- Heating unit (HK) for process chamber

32

27. Method for cleaning contaminated workpieces, in particular using a device (1) according to one of claims 1 to 25, the method having the following steps: a) introducing a contaminated workpiece into a receiving unit (AE); b) introducing the receiving unit (AE) with the contaminated workpiece into a process chamber (PK1, PK2, PK3); c) filling the process chamber (PK1, PK2, PK3) with a cleaning liquid (RF) up to a filling level which corresponds to a partial filling of the process chamber with cleaning liquid (RF); d) hermetically closing the process chamber (PK1, PK2, PK3) by means of a closing unit (VE), which is attached in particular to the receiving unit (AE); e) evacuating a vacuum tank (VT) by means of a vacuum pump (VP); f1) establishing a first fluid connection between a location above the filling level of the cleaning liquid (RF) filled process chamber (PK1, PK2, PK3) and the vacuum tank (VT) by opening a first valve (V1); g1) blocking the first fluid connection by closing the first valve (V1); f2) establishing a second fluid connection between a location above the filling level of the process chamber (PK1, PK2, PK3) filled with cleaning liquid (RF) and the atmosphere by opening a second valve (V2); g2) blocking the second fluid connection by closing the second valve (V2); h) removing cleaning liquid (RF) from the process chamber (PK1, PK2, PK3) and from the cleaned workpiece; i) opening the process chamber (PK1, PK2, PK3) by means of the closure unit (VE); j) leading out the receiving unit (AE) with the cleaned workpiece from the process chamber (PK1, PK2, PK3); k) removing the cleaned workpiece from the receiving unit (AE).

28. The method according to claim 27, characterized in that after the opening of the first valve (V1) in step f1), the closing of the first valve (V1) in step g1) takes place before more than 1/10, preferably more than 1/ 100, the volume of the cleaning liquid has passed the first valve (V1).

33 (-> by foam sensor and/or by keeping the valve open for a sufficiently short time between steps f1) and g1))

29. The method according to claim 27 or 28, characterized in that during at least one of steps c) to h) from an ultrasound source (US, US1, US2, US3) ultrasound is introduced into the cleaning liquid.

30. The method according to any one of claims 27 to 29, characterized in that before step f1) of an ultrasound source (US, US1, US2, US3) ultrasound is introduced into the cleaning liquid.

31. The method according to any one of claims 27 to 30, characterized in that during at least one of steps c) to h) the introduced workpiece is moved relative to the process chamber and relative to the cleaning liquid (RF).

32. The method according to any one of claims 27 to 31, characterized in that the removal of cleaning liquid from the process chamber (PK1, PK2, PK3) and from the cleaned workpiece in step h) comprises rotating the receiving unit (AE) with the cleaned workpiece , wherein the receiving unit is rotated about an axis of rotation by means of a rotation unit (RE). (-> spin)

33. The method according to any one of claims 27 to 32, characterized in that the removal of cleaning liquid from the process chamber (PK1, PK2, PK3) and from the cleaned workpiece in step h) involves drying the cleaned workpiece in the process chamber (PK1, PK2 , PK3) by means of a drying fan (TV), wherein a heating unit (HE) for the drying air is preferably arranged between the drying fan and the respective process chamber (PK1, PK2, PK3).

34. The method as claimed in one of claims 27 to 33, characterized in that the sequence of steps e), f1), g1), f2), g2) is run through several times in one of the process chambers (PK1, PK2, PK3).

34

35. The method according to any one of claims 27 to 34, characterized in that step e) of evacuation lasts permanently while the sequence of steps f1), g1), f2), g2) in one of the process chambers (PK1, PK2, PK3 ) is run through several times.

36. The method as claimed in one of claims 27 to 35, characterized in that the sequence of steps b) to j) is run through several times and in each case in different process chambers (PK1, PK2, PK3).

37. The method according to any one of claims 27 to 36, characterized in that after drying and heating the cleaned workpiece in a process chamber (PK1, PK2, PK3), steps e) and f1) are carried out again.

38. The method as claimed in claim 37, characterized in that the sequence of steps f1), g1), f2) and g2) is run through several times.

39. The method according to any one of claims 27 to 38, characterized in that when establishing the first fluid connection by opening the first valve (V1) in step f1) at the location above the filling level of the process chamber (PK1, PK2, PK3) filled with cleaning liquid a pressure drop Ap from an initial pressure p1 to a final pressure p2 occurs during a period At, with the initial pressure p1 being between 0.9 bar and 1.1 bar (0.9 bar < p1 < 1.1 bar), the final pressure p2 being between 0.01 bar and 0.3 bar (0.01 bar < p2 < 0.3 bar), and the duration At is in the range of 50 ms to 200 ms (50 ms < At < 200 ms).

40. The method according to any one of claims 27 to 39, characterized in that the cleaning liquid (RF) has a temperature in the range from 10°C to 70°C and preferably in the range from 20°C to 50°C.

35