Patent Application
20250027205
The present invention relates to a method for passivating a surface of a workpiece, said method comprising the following:
Such a method is known from DE 10 2007 022 033 A1.
In this known method, the interior space of a treatment chamber is flooded with a passivating agent multiple times, the passivating agent being completely discharged from the treatment chamber after each flooding.
If the workpiece to be passivated has constrictions such as bores with a small diameter, capillaries, and small lumens, the penetration of the passivating agent into such constrictions is impeded by the surface tension of the passivating agent.
An exchange between air present in the workpiece and the passivating agent occurs only to an insufficient extent. Workpieces with complex geometry are therefore passivated incompletely and insufficiently, at least in such constrictions. Also pre-processes such as, e.g., electropolishing cannot be performed completely for these reasons.
In accordance with an embodiment of the invention, a method is created for passivating a surface of a workpiece of the kind stated at the outset, said method enabling a complete and sufficient passivation of the surface of the workpiece in narrow cavities of the workpiece, even in the case of workpieces with complex geometry.
In accordance with an embodiment of the invention, a method for passivating a surface of a workpiece is provided, said method having the features of the preamble of claim 1, wherein the method further comprises the following:
The concept underlying the invention is to generate cyclical pressure changes in the closed treatment chamber, wherein the treatment chamber is preferably evacuated to a lower pressure value and then ventilated up to an upper pressure value.
Due to these repeated pressure changes, the passivating agent is also reliably introduced into narrow cavities of a workpiece to be passivated.
If another fluid is contained in cavities of the workpiece due to pre-processes, this fluid is thus reliably exchanged for passivating agent through the pressure changing operations. As a result, it is ensured during the passivating process that the passivating agent can securely coat all surfaces of the workpieces and the formation of a gapless passivation layer can reliably take place.
The provision of the passivating agent in the treatment chamber can take place by the passivating agent being introduced into the treatment chamber after the introduction of the workpiece into the treatment chamber. This is preferably the case with chamber systems for treating workpieces.
Alternatively hereto, provision may also be made that the passivating agent is already located in the treatment chamber before the introduction of the workpiece into the treatment chamber. In this case, provision may also be made that the passivating agent remains in the treatment chamber after the passivation treatment. This is preferably the case with in-line immersion systems for treating workpieces.
Passivation of a workpiece refers to the removal of free iron molecules and the targeted creation of a protective layer on a metallic workpiece, the oxygen corrosion of the base material of the workpiece thereby being prevented or slowed down considerably.
The standards ASTM A380-06 and ASTM A967-05 are relevant for the passivation of surfaces of a workpiece. Furthermore, the specifications ISO 16048, AMS 2700 and QQ-P-35 are applicable.
The workpiece to be passivated may be made, for example, entirely or partially of a stainless steel material, which has a chromium content of at least 11% by weight.
The workpiece to be passivated may be produced, in particular, in an additive manufacturing process.
The workpiece to be passivated may be a workpiece from the field of medical technology, for example an implant or an instrument.
The workpiece to be passivated may have, e.g., a structured, in particular biocompatible, surface.
Such a surface may be provided, in particular, to intergrow with bone structures.
The workpiece to be passivated preferably has narrow cavities such as, for example, bores or capillaries into which liquids are not easily able to penetrate from the outside.
In a preferred embodiment of the invention, provision is made that the maximum pressure po is less than the ambient pressure (about 1.0 bar) during the cyclical changing of the pressure in the treatment chamber.
Furthermore, it is favorable if the minimum pressure pu is less than half the maximum pressure po during the cyclical changing of the pressure in the treatment chamber.
Furthermore, it is advantageous if the minimum pressure pu is less than the vapor pressure of the passivating agent during the cyclical changing of the pressure in the treatment chamber.
Due to the cyclical pressure change in the treatment chamber, cavitation bubbles are created directly on the surfaces of the workpiece. A portion of these cavitation bubbles is stable and changes its volume in the course of the pressure change; the volume of the cavitation bubbles decreases when the pressure rises and increases when the pressure falls.
Due to these volume changes, micro-flows are created in the bath of the passivating agent and, in particular, in cavities of the workpiece to be passivated.
In a low pressure phase, the stable cavitation bubbles expand in the capillaries of the workpieces, fluid thereby being ejected from the capillaries.
In a subsequent phase with higher pressure, the stable cavitation bubbles contract, fluid thereby being sucked into the capillaries.
Another portion of the cavitation bubble is not stable, but instead is formed as transient cavitation bubbles. These transient cavitation bubbles implode when the pressure in the treatment chamber is increased, which leads to very high flow speeds on the surface of the workpiece.
The micro-flows in the bath of passivating agent bring about a very effective exchange of the fluid on the surfaces of the workpiece, particularly on the surfaces of bores and/or capillaries of the workpiece.
A high concentration of oxygen on the surface of the workpiece to be passivated facilitates the formation of oxides and the formation of a passivation layer.
In a particular embodiment of the passivation method, the oxygen concentration in the passivating agent within the treatment chamber is therefore detected by at least one measuring sensor.
When the oxygen concentration in the passivating agent falls below a lower limit value, the oxygen concentration is raised by supplying air into the treatment chamber.
In order to enable such a supply of air into the passivating agent within the treatment chamber, provision may be made that the treatment chamber is provided with at least one bead nozzle.
The limit value of the oxygen concentration below which a supply of oxygen to the passivating agent is performed is preferably at least 5 mg/l and/or preferably at most 8 mg/l.
The average cycle duration ti of the changing of the pressure in the treatment chamber is preferably at least 1 second, in particular at least 3 seconds, particularly preferably at least 5 seconds.
Furthermore, the average cycle duration ti of the changing of the pressure in the treatment chamber is preferably at most 30 seconds, particularly preferably at most 10 seconds.
The passivation process, which comprises numerous pressure change cycles, is performed during a treatment time of preferably at least one minute, in particular at least 5 minutes, particularly preferably at least 10 minutes.
Furthermore, the passivation process is preferably performed during a treatment time of at most 60 minutes, in particular at most 30 minutes, particularly preferably at most 20 minutes.
In a preferred embodiment of the method in accordance with the invention, provision is made that the treatment chamber is connected to a negative pressure source during the changing of the pressure at least at times.
Such a negative pressure source may comprise, for example, a vacuum pump, preferably a positive displacement vacuum pump.
Provision may further be made that the negative pressure source comprises a negative pressure store.
Such a negative pressure store is preferably separable from the interior space of the treatment chamber by a valve or a valve arrangement.
Furthermore, the negative pressure store is preferably connectable to a vacuum generator, for example a vacuum pump, in order to lower the pressure in the negative pressure store.
During phases of the passivation process during which the negative pressure store is separated from the treatment chamber by the valve or the valve arrangement, the internal volume of the negative pressure store can be evacuated by means of the vacuum generator to a pressure that is significantly lower than the pressure in the treatment chamber.
Due to a subsequent pressure equalization between the negative pressure store and the interior space of the treatment chamber, the pressure in the interior space of the treatment chamber can then be lowered significantly in a simple manner, preferably below the vapor pressure of the passivating agent that is located in the interior space of the treatment chamber. It is thereby possible to increase the depth of action of the evaporation of the treatment agent in the interior space of the treatment chamber.
Here, the depth of action is the distance (taken in parallel to the direction of gravity) from the surface of the bath of the passivating agent up to which an evaporation process takes place in the passivating agent.
Furthermore, it is possible to provide a mechanism in the negative pressure store for separating liquid droplets entrained with the gas stream from the interior space of the treatment chamber. Such a mechanism may comprise, e.g., a wire mesh mist eliminator, an impact separator, and/or a condenser, which preferably has a cooled face.
Furthermore, a mechanism may be provided in the negative pressure store that precipitates vapor of the treatment agent entrained with the gas stream from the interior space of the treatment chamber, said precipitation taking place actively or passively through condensation.
Such a mechanism may comprise, e.g., a condenser, which preferably has a cooled face.
It is particularly favorable if the negative pressure store is provided with a heat exchanger.
In such a heat exchanger, which may act, in particular, as a condenser, heat from the gas stream reaching the negative pressure store from the treatment chamber can be transferred to a heat removal medium. If a vapor of the passivating agent condenses on the heat exchanger, in particular, the condensation heat thereby released can be transferred to the heat removal medium.
The heat removal medium may be a treatment agent to be supplied to the treatment chamber, for example a passivating agent or a rinsing liquid.
The heat removal medium may also serve to indirectly heat a treatment agent to be supplied to the treatment chamber, for example a passivating agent or a rinsing liquid.
For this purpose, it is particularly favorable if the heat removal medium is used as a coolant of a heat pump.
Furthermore, it is possible to heat a treatment agent of another treatment process or to heat a building by means of the heated heat removal medium.
The passivating agent is preferably an aqueous solution to which at least one acid is added.
For example, provision may be made that the passivating agent comprises citric acid.
Here, the proportion of the citric acid may be preferably at least 4% by weight and/or preferably at most 10% by weight.
Alternatively or in addition hereto, provision may be made that the passivating agent comprises phosphoric acid and/or nitric acid.
For example, an aqueous solution of nitric acid may be used as a passivating agent, said solution containing nitric acid in a proportion of at least 20% by volume and at most 55% by volume, in particular at most 45% by volume, particularly preferably at most 25% by volume.
Alternatively hereto, provision may be made that the passivating agent contains phosphoric acid in a concentration of at least 1.5% by volume and/or at most 3% by volume.
In a preferred embodiment of the invention, provision is made that the passivating agent is an aqueous solution of phosphoric acid and nitric acid, wherein the passivating agent contains phosphoric acid in a concentration of 1.5% by volume to 3% by volume and nitric acid in a concentration of 0.1% by volume to 0.5% by volume.
Furthermore, the passivating agent contains non-ionic surfactants in a concentration of preferably 0.05% by volume to 0.5% by volume.
A basis of the aqueous solution is preferably demineralized water having an electrical conductivity of at most 10 μS/cm.
In order to facilitate the creation of micro-flows directly on the surface of a workpiece to be passivated in combination with the cyclical pressure changes and to thus obtain an even greater exchange of the fluids in cavities of the workpiece, provision may be made that the passivating agent and/or the at least one workpiece is/are acted upon with ultrasound during the changing of the pressure.
Here, the ultrasonic frequency is preferably at least 20 kHz, particularly preferably at least 25 kHz.
Furthermore, the ultrasonic frequency is preferably at most 120 kHz, particularly preferably at most 80 KHz.
The ultrasonic power coupled into the interior space of the treatment chamber is preferably at least 5 watts per liter of passivating agent in the treatment chamber, particularly preferably at least 8 watts per liter of passivating agent in the treatment chamber.
Furthermore, the ultrasonic power coupled into the treatment chamber is preferably at most 20 watts per liter of passivating agent in the treatment chamber, particularly preferably at most 15 watts per liter of passivating agent in the treatment chamber.
By modulating the amplitude of the ultrasonic vibrations and/or by modulating the ultrasonic frequency (so-called “sweep” function), the effect of the action on the bath of passivating agent and/or the workpiece to be passivated can be further intensified and the effect of the application of ultrasound can be distributed uniformly over all surfaces of the workpiece to be passivated.
In a preferred embodiment of the method in accordance with the invention, provision is made that a workpiece to be passivated is introduced into a plurality of passivation stations one after the other, which contain different passivating agents.
Because a plurality of passivation stations are provided in which different workpieces to be passivated are passivated simultaneously, the throughput of a passivation system used for the passivation method can be increased.
The bath of the passivation station into which the workpiece is first introduced is most heavily contaminated and the bath of the passivation station into which the workpiece is last introduced is least contaminated. As a result, the surface quality and the cleanliness of the passivated workpiece are further improved.
For processing the passivating agent, the passivating agent can be conveyed in a cascade partially from the passivation state located further back in the treatment sequence into the passivation station located further ahead in the treatment sequence.
The passivating agent from the passivation station located first in the treatment sequence can be partially discarded.
In the multi-stage passivation method, the treatment temperature and/or the concentration of the acid in the respective passivating agent may be different in the different passivation stations.
Here, it is particularly favorable if in the passivation state located last in the treatment sequence the concentration of the acid in the passivating agent is lowest, such that less acid is carried over from this passivation station, for example into a subsequent rinsing station.
The treatment temperature in a passivation station located further ahead in the treatment sequence may be at least 10% higher and/or at most 20% higher than the treatment temperature in a passivation station located further back in the treatment sequence (the percentages referring to the absolute temperature of the respective passivating agent).
It is further favorable if the concentration of the acid in the passivating agent in the passivation station located further ahead in the treatment sequence is at least 50% higher than the concentration of the acid in the passivating agent in the passivation station located further back in the treatment sequence.
Provision may further be made that the concentration of the acid in the passivating agent in the passivation station located further ahead in the treatment sequence is at most 80% higher than the concentration of the acid in the passivating agent in the passivation station located further back in the treatment sequence.
If a workpiece to be passivated is treated in two separate treatment chambers one after the other, provision may thus be made, for example, that the workpiece in the first passivation station is immersed in the passivating agent and that the workpiece in the subsequent passivation station is sprayed with the passivating agent and/or the passivating agent is poured thereover.
In accordance with an embodiment of the invention, an apparatus is created for passivating workpieces, said apparatus enabling a complete and sufficient passivation of the surface of a workpiece to be passivated, even when the workpiece has a complex geometry and/or narrow cavities.
This object is achieved, in accordance with the invention, in an apparatus for passivating workpiece, said apparatus having the features of the preamble of claim 14, in that the apparatus comprises a pressure changing apparatus for cyclically changing the pressure in the treatment chamber while passivating agent is located in the treatment chamber.
Particular embodiments of such an apparatus in accordance with the invention for passivating workpieces have already been explained above in connection with particular embodiments of the method in accordance with the invention for passivating a surface of a workpiece.
In a particular embodiment of the apparatus in accordance with the invention, provision is made that the apparatus comprises at least two treatment chambers, wherein a workpiece is treatable with a passivating agent in the first treatment chamber and a workpiece is rinsable with a rinsing liquid in the second treatment chamber simultaneously.
The apparatus in accordance with the invention for passivating workpieces is suitable, in particular, for performing the method in accordance with the invention for passivating a surface of a workpiece.
The method in accordance with the invention for passivating a surface of a workpiece is preferably performed by means of the apparatus in accordance with the invention for passivating workpieces.
For many applications of a workpiece to be passivated, in particular for applications as a medical technology product, the workpieces passivated by means of the method in accordance with the invention or the workpieces passivated by means of the apparatus in accordance with the invention are permitted to have no residue of the passivating agent on their surfaces after the passivation process. In particular when a passivated workpiece has a cavity, it must be ensured by means of a suitable process that the passivating agent is rinsed out of such a cavity.
Therefore, a rinsing process may follow the passivating process.
The rinsing process may be performed in the same treatment chamber as the passivation process.
Alternatively thereto, provision may be made that the rinsing process is performed in a different treatment chamber or in an open treatment basin.
For example, demineralized water is used as a rinsing liquid.
The workpiece to be rinsed is preferably immersed completely or partially into the rinsing liquid.
When the rinsing process is performed in a closed treatment chamber, the pressure in the treatment chamber may thus also be cyclically changed, as has been described in connection with the passivation process.
Due to the cyclical pressure changes, the rinsing liquid is then flushed into constrictions and capillaries of the passivated workpiece, the passivating agent thereby being flushed out at the same time.
The rinsing effect can be facilitated by acting upon the bath of the rinsing liquid and/or the workpiece in the treatment chamber or in the open treatment basin by means of ultrasound, for example by an ultrasonic oscillator.
Further features and advantages of the invention are subject matter of the subsequent description and the graphical representation of exemplary embodiments.
The same or functionally equivalent elements are provided with the same reference numerals in all Figures.
An apparatus, schematically depicted in
In order to be able to introduce a workpiece 102 into the interior space 106 of the treatment chamber 104, provision is preferably made that the treatment chamber 104 comprises a tank 110 (see
In order to be able to fill the treatment chamber 104 with treatment agent, in particular passivating agent, the interior space 106 of the treatment chamber 104 is connected to a storage container 122 by way of a supply line 120.
The supply line 120 is openable or closeable by means of a valve 124 arranged therein.
The supply line 120 opens in a clean region 126 of the storage container 122, which is filled with a treatment agent, in particular a passivating agent, which is prepared for a treatment operation in the treatment chamber 104.
The clean region 126 is separated from a dirty region 130 of the storage container 122 by a separating wall 128.
Located at the upper rim of the separating wall 128 is an overflow 132 by way of which treatment agent is able to travel from the clean region 126 into the dirty region 130.
The treatment agent located in the dirty region 130 is prepared for use in the treatment chamber 104 by being transferred from the dirty region 130 of the storage container 122 into the clean region 126 of the storage container 122 by way of a filtration line 134.
A filtration pump 136, a filter 138, and a flow restrictor 140 are arranged in the filtration line 134.
An emptying of the treatment agent, in particular the passivating agent, from the interior space 106 of the treatment chamber 104 is possible by means of an emptying line 148, which is preferably connected at a lowest point of the interior space 106 of the treatment chamber 104 and which opens into the dirty region 130 of the storage container 122.
The emptying line 148 is openable and closeable by means of a valve 150 arranged therein.
For monitoring the treatment process in the treatment chamber 104, the treatment chamber 104 is provided with different sensors, in particular with a pressure sensor 152, a temperature sensor 154, and a lower level sensor 156 and/or an upper lever sensor 158.
By means of the lower level sensor 156, it is determined whether the interior space 106 of the treatment chamber 104 is completely emptied of treatment agent.
With the upper lever sensor 158, it is determined whether the interior space 106 of the treatment chamber 104 is completely filled with liquid treatment agent, in particular passivating agent.
In order to be able to cyclically change the pressure in the treatment chamber 104, the apparatus 100 for passivating workpieces 102 further comprises a pressure changing apparatus 160, which in the depicted embodiment comprises an evacuation valve 296, a separator 166, and a vacuum generator 168.
The evacuation valve 296 is connected to a pressure change outlet 174 of the treatment chamber 104 by way of a pressure change line 172.
Furthermore, the evacuation valve 296 is connected to an inlet 180 of the separator 166 by way of an evacuation line 178.
Gas stemming from the interior space 106 of the treatment chamber 104, said gas being loaded with a vapor of the treatment agent and/or with droplets of the treatment agent, in particular the passivating agent, travels through the inlet 180 into the interior space 182 of the separator 166, which may be configured, for example, as a cyclone in order to separate droplets contained in the entering gas stream from the gas stream by centrifugal action.
The separator 166 may further contain a condensation apparatus 184, which comprises, e.g., impact plates and/or a demister and/or a cooled heat exchanger on which vapor of the treatment agent, in particular the passivating agent, condenses and is thus able to be separated out of the gas stream flowing through the separator 166.
The gas stream, freed of droplets and/or vapor of the treatment agent by means of the separator 166, travels through a suction line 186 to a suction-side inlet 188 of the vacuum generator 168.
The vacuum generator 168 may be configured, e.g., as a vacuum pump 190, preferably as a positive displacement vacuum pump.
The gas stream then travels via a pressure-side outlet 192 of the vacuum generator 168 into a pressure line 194 and from there, for example, into the environment of the apparatus 100.
The pressure changing apparatus 160 further comprises a ventilation valve 298.
The ventilation valve 298 is connected to the pressure change outlet 174 of the treatment chamber 104 by way of the (branching) pressure change line 172.
Furthermore, the ventilation valve 298 is connected to a ventilation line 198, by means of which ambient air is suppliable to the ventilation valve 298.
The pressure changing apparatus 160 is switchable from an evacuation state, in which the evacuation valve 296 connected to the evacuation line 178 is open and the ventilation vale 298 connected to the ventilation line 198 is closed, into a ventilation state, in which the ventilation valve 298 connected to the ventilation line 198 is open and the evacuation valve 296 connected to the evacuation line 178 is closed.
Furthermore, the pressure changing apparatus 160 can be switched into a holding state in which both the evacuation valve 296 and the ventilation valve 298 are closed, such that the pressure in the treatment chamber 104 is held substantially constant.
The switching of the evacuation valve 296 and/or the ventilation valve 298 between the open and the closed state may, in principle, take place in any manner, for example mechanically, electromechanically, pneumatically, hydraulically, or electromagnetically.
All switchable valves of the apparatus 100 and the sensors, for example the pressure sensor 152, the temperature sensor 154, the lower level sensor 156, and the upper level sensor 158, are connected by means of signal and control lines (not depicted) to a control apparatus (not depicted) of the apparatus 100 for passivating workpieces 102, such that the control apparatus is able to receive and process signals from the sensors and is able to switch the switchable valves from one state into the other state.
The control apparatus of the apparatus 100 is preferably programmable, such that a control program for controlling a method for passivating workpieces 102 is performable by means of the control apparatus and the sensors and actuators controlled thereby.
In the operation of the apparatus 100, condensate collected in the separator 166 can be removed from the interior space 182 of the separator 166 by means of a condensate trap 200.
The condensate trap 200 comprises a first sluice valve 204 connected at a condensate outlet 202 of the separator 166, a second sluice valve 206 arranged downstream of the first sluice valve 204, and a sluice space 208 arranged between the first sluice valve 204 and the second sluice valve 206.
The condensate deposited in the separator 166 travels into the sluice space 208 of the condensate trap 200 by opening the first sluice valve 204 while the second sluice valve 206 is closed at the same time.
After the sluice space 208 is filled with condensate, the first sluice valve 204 is closed and the second sluice valve 206 is opened.
The second sluice valve 206 is connected to the dirty region 130 of the storage container 122 by way of a condensate line 210, such that the condensate deposited in the separator 166 travels via the condensate trap 200 into the storage container 122.
By means of the apparatus 100 described above for passivating workpieces, a method for passivating workpieces is performed as follows:
Before the passivation of a workpieces 102, all surfaces of the workpiece 102 must be freed of all filmic, particulate, and other contaminants and residue of cleaning agents. Therefore, an intensive cleaning of the workpiece 102 with subsequent rinsing of all surfaces of the workpiece 102 takes place before the passivation process.
The treatment chamber 104 of the apparatus 100 is provided with a closure device, for example with a lid 116.
This closure device enables an air-tight closure of the treatment chamber 104.
When the closure device is open, in particular when the lid 116 is raised, the workpiece 102 to be treated is introduced into the interior space 106 of the treatment chamber 104.
The workpiece 102 may be held on a workpiece receptacle 212.
After the introduction of the workpiece 102 into the interior space 106 of the treatment chamber 104, the treatment chamber 104 is closed in an air-tight manner by means of the closure device.
If no bath of the treatment agent, in particular the passivating agent, is present in the interior space 106 of the treatment chamber 104, a desired amount of treatment agent is sucked from the storage container 122 through the supply line 120. For this purpose, the valve 124 in the supply line 120 is opened.
The pressure changing device 160 is first in the evacuation state in which the evacuation valve 296 is open and the ventilation valve 298 is closed. The vacuum generator 168, in particular the vacuum pump 190, is in operation and sucks gas, which may be loaded with vapor of the treatment agent and with droplets of the treatment agent, through the pressure changing line 172, the evacuation line 178, the separator 166, and the suction line 186 to the suction-side inlet 188 of the vacuum generator 168.
Here, droplets of the treatment agent entrained with the suctioned gas are separated in the separator 166. Furthermore, the vapor of the treatment agent entrained with the gas condenses in the condensation apparatus 184.
The treatment agent collected in the lower region of the separator 166 can be fed via the condensate trap 200 and the condensate line 210 to the dirty region 130 of the storage container 122 when a predetermined fill level is reached or after a predetermined operation time interval.
The separator 166 may also serve as a negative pressure store.
In this way, the pressure in the interior space 106 of the treatment chamber 104 is reduced from atmospheric pressure (about 1.0 bar) to a lower pressure value pu. After reaching a lower pressure value pu, the pressure in the treatment chamber 104 is cyclically changed during a passivation duration, i.e., increased from the lower pressure value pu up to an upper pressure value po and then lowered again to the lower pressure value pu (see
This process can be repeated, in particular periodically.
Between the pressure increase phases and the pressure reduction phases, the pressure in the treatment chamber 104 can remain at the lower pressure value pu or at the upper pressure value po by the pressure changing apparatus 160 being switched into the holding state, in which the evacuation valve 296 and the ventilation valve 298 are closed.
To increase the pressure in the treatment chamber 104, the pressure changing apparatus 160 is switched by the control apparatus into the ventilation state, in which the evacuation valve 296 is closed and the ventilation valve 298 is open, such that ambient air travels through the ventilation line 198 and the pressure change line 172 into the interior space 106 of the treatment chamber 104.
The lower pressure value pu is preferably at least 20 mbar and/or preferably at most 500 mbar, in particular at most 300 mbar.
The upper pressure value pu is preferably at least 700 mbar and/or preferably at most 1 bar.
The cycle duration ti of a complete pressure cycle is preferably at least 1 second, in particular at least 3 seconds, particularly preferably at least 5 seconds.
Furthermore, the cycle duration ti of a complete pressure cycle is preferably at most 30 seconds, particularly preferably at most 10 seconds.
The workpiece 102 is arranged in the interior space 106 of the treatment chamber 104 such that it is immersed at least partially or completely in a bath of the treatment agent, in particular the passivating agent.
If the workpiece 102 has narrow tubes, so-called capillary tubes, it is thus favorable if said capillary tubes are oriented substantially vertically, wherein an end of each tube projects into the passivating agent and the opposite end of the tube projects into the region of the interior space 106 of the treatment chamber 104 that is filled with gas. Due to the hydrostatic pressure, the passivating agent is then sucked into the capillary tubes.
By means of this process, the fluid is reliably exchanged, said fluid being present on the surface of the workpiece 102 or in bores or capillaries of the workpiece 102 due to pre-processes.
As a result, during the passivating process, it is ensured that the passivating agent is able to completely coat all surfaces of the workpiece 102, such that the formation of a passivation layer takes place on all surfaces of the component 102.
The passivation process, which comprises numerous pressure change cycles, is performed during a passivation time of preferably at least 1 minute, in particular at least 5 minutes, particularly preferably at least 10 minutes.
Furthermore, the passivation process is preferably performed during a passivation time of at most 60 minutes, in particular at most 30 minutes, particularly preferably at most 20 minutes.
The temperature of the passivating agent during the passivation process is preferably at least 20° C., in particular at least 30° C., particularly preferably at least 50° C.
Furthermore, the temperature of the passivating agent during the passivation process is preferably at most 90° C., in particular at most 70° C., particularly preferably at most 65° C.
For performing the passivation process, a passivating agent is used as a treatment agent.
The passivating agent preferably has the following chemical composition:
A basis of the passivating agent is demineralized water having an electrical conductivity of at most 10 μS/cm.
The passivating agent further contains phosphoric acid in a concentration of 1.5% by volume to 3% by volume, nitric acid in a concentration of 0.1% by volume to 0.5% by volume, and non-ionic surfactants in a concentration of 0.05% by volume to 0.5% by volume.
Alternatively hereto, for example, an aqueous solution of nitric acid may be used as a passivating agent, said solution containing nitric acid in a proportion of at least 20% by volume and at most 55% by volume, in particular at most 45% by volume, particularly preferably at most 25% by volume.
Furthermore, an aqueous solution of citric acid may be used as an alternative passivating agent, wherein the proportion of citric acid is preferably at least 4% by weight and/or preferably at most 10% by weight.
The pH value of the passivating agent is preferably at least 1.8 and/or preferably at most 2.2.
Due to the cyclical pressure change in the treatment chamber 104, cavitation bubbles are created directly on the surfaces of the workpiece 102 or the plurality of workpieces 102. A portion of these cavitation bubbles is stable and change its volume in the course of the pressure change; the volume of the cavitation bubbles decreases when the pressure rises and increases when the pressure falls.
Due to these volume changes, micro-flows are created in the bath of the passivating agent and, in particular, in cavities of the workpiece 102 to be passivated.
In a low pressure phase, the stable cavitation bubbles expand in the capillaries of the workpiece 102, fluid thereby being ejected from the capillaries.
In a subsequent phase with higher pressure, the stable cavitation bubbles contract, fluid thereby being sucked into the capillaries.
Another portion of the cavitation bubble is not stable, but instead is formed as transient cavitation bubbles. These transient cavitation bubbles implode when the pressure in the treatment chamber 104 increases, which leads to very high flow speeds on the surface of the workpiece 102.
The micro-flows in the bath of passivating agent bring about a very effective exchange of the fluid on the surfaces of the workpiece 102, particularly on the surfaces of bores and/or capillaries of the workpiece 102.
A high concentration of oxygen on the surface of the workpiece 102 to be passivated facilitates the formation of oxides and thus the formation of a passivation layer.
Therefore, in a preferred embodiment of the passivation method, the oxygen concentration in the passivating agent within the treatment chamber 104 is detected by at least one measuring sensor.
When the oxygen concentration in the passivating agent falls below a lower limit value, the oxygen concentration is raised by supplying air into the lower region of the treatment chamber 104. In order to enable such a supply of air into the passivating agent, provision may be made that the treatment chamber 104 is provided with at least one bead nozzle.
The limit value of the oxygen concentration below which a supply of oxygen to the passivating agent is performed is preferably at least 5 mg/l and/or preferably at most 8 mg/l.
In order to facilitate the creation of micro-flows directly on the surface of a workpiece 102 to be passivated in combination with the cyclical pressure changes and to thus obtain a greater exchange of the fluids, provision may be made that the apparatus 100 is provided with at least one ultrasonic oscillator 214, by means of which the bath of the treatment agent in the interior space 106 of the treatment chamber 104 and/or the workpiece 102 is able to be acted upon with ultrasound.
Here, the ultrasonic frequency is preferably at least 20 kHz, particularly preferably at least 25 kHz.
Furthermore, the ultrasonic frequency is preferably at most 120 kHz, particularly preferably at most 80 KHz.
The ultrasonic power coupled into the interior space 106 of the treatment chamber 104 by means of the ultrasonic oscillator 214 or by means of a plurality of ultrasonic oscillators 214 is preferably at least 5 watts per liter of passivating agent in the treatment chamber 104, particularly preferably at least 8 watts per liter of passivating agent in the treatment chamber 104.
Furthermore, the ultrasonic power coupled into the treatment chamber 104 is preferably at most 20 watts per liter of passivating agent in the treatment chamber 104, particularly preferably at most 15 watts per liter of passivating agent in the treatment chamber 104.
By modulating the amplitude of the ultrasonic vibrations and/or by modulating the ultrasonic frequency (so-called “sweep” function), the effect of the action on the bath of passivating agent and/or the workpiece 102 can be further intensified and the effect of the application of ultrasound can be distributed uniformly over all surfaces of the workpiece 102 to be passivated.
In order to uniformly and completely passivate all regions of a workpiece 102 that is held on the workpiece receptacle 212, or all workpieces 102 of a group of workpieces 102 that are held on the workpieces receptacle 212 simultaneously, it is favorable if the apparatus 100 comprises a rotating apparatus, by means of which the workpiece receptacle 212 and thus the workpiece 102 or the workpieces 102 are rotatable about a rotational axis during the passivation treatment.
The rotational axis is hereby preferably oriented substantially horizontally.
This rotational movement prevents air bubbles from collecting in the workpiece 102 or in the workpieces 102 and preventing a coating with the passivating agent.
Furthermore, by means of the rotating apparatus, it is possible to empty cavities of the workpiece 102 or the workpieces 102 when orifices of the cavities are located above the surface of the passivating agent bath in the treatment chamber 104.
Alternatively or in addition to such a rotating apparatus, provision may also be made that the apparatus 100 comprises a vertical movement apparatus for the workpiece 102 or for a plurality of workpieces 102. By means of such a vertical movement apparatus, the workpiece 102 or the workpieces 102 are moveable along the direction of gravity relative to the bath of passivating agent. The flow of the passivating agent caused by this relative movement facilitates the exchange of the passivating agent on the surfaces of the workpiece 102 to be passivated.
The filter 138 arranged in the filtration line 134, by means of which contaminants are removed from the passivating agent that enters the dirty region 130, may comprise a solids filter.
Furthermore, the filer 138 may also comprise a magnetic retaining apparatus, by means of which iron molecules are removable from the passivating agent.
Such a magnetic retaining apparatus preferably comprises at least one permanent magnet.
Such a magnetic retaining apparatus is advantageously integrated into a housing of the filter 138.
When the passivating agent is reprocessed in the filtration line 134, the concentration of the acid content in the passivating agent can also be monitored and, if necessary, brought into the desired range by adding acid or by adding water.
Such a concentration monitoring may take place, for example, by means of a conductivity measurement of the passivating agent or by means of a refractometer.
For many applications, the workpieces 102 passivated by means of the apparatus 100 are not permitted to have any residue of the passivating agent on their surfaces for reprocessing. In particular when a passivated workpiece 102 has a cavity, it must be ensured by means of a suitable process that the passivating agent is rinsed out of such a cavity to sufficient extent.
Therefore, a rinsing process may follow the passivating process described above.
For example, demineralized water is used as a rinsing liquid.
To perform the rinsing process, the passivating agent is emptied into the storage container 122 via the open valve 150 and the emptying line 148.
The interior space 106 of the treatment chamber 104 is then filled at least partially with the rinsing liquid by means of a rinsing liquid supply (not graphically represented).
During the rinsing process, the pressure in the treatment chamber 104 may also be cyclically changed, as has been described in connection with the passivation process.
Due to the cyclical pressure changes, the rinsing liquid is flushed into constrictions and capillaries of the passivated workpiece 102, the passivating agent thereby being flushed out at the same time.
The rinsing effect and thus the removal of the passivating agent from the surfaces of the workpiece 102 can be facilitated by acting upon the bath of the rinsing liquid and/or the workpiece 102 in the treatment chamber 104 with ultrasound, for example by the ultrasonic oscillator 214, for example through the creation of micro-flows near the surface.
A second embodiment, depicted schematically in
A first negative pressure store 224a is connected by way a first supply line 226a in which a first supply valve 228a is arranged to a pressure change line 172 connected to the treatment chamber 104.
Furthermore, the first negative pressure store 224a is connected by way of a first discharge line 230a in which a first discharge valve 232a is arranged to an evacuation line 178 leading to the inlet 180 of the separator 166. A suction line 186 leads from the outlet of the separator 166 to the suction-side inlet 188 of the vacuum generator 168.
A second negative pressure store 224b is connected by way of a second supply line 226b in which a second supply valve 228b is arranged to the pressure change line 172.
Furthermore, the second negative pressure store 224b is connected to the evacuation line 178 by way of a second discharge line 230b in which a second discharge valve 232b is arranged.
Each of the negative pressure stores 224 is coolable by means of a heat exchanger 234 that is able to be flowed through by a coolant or a heat removal medium during the operation of the apparatus 100 in order to condense out a vapor of a treatment agent, in particular a passivating agent, from the gas stream entering the respective negative pressure store 224.
Furthermore, the pressure changing apparatus 160 in this embodiment comprises a ventilation line 198, in which a ventilation valve 236 is arranged and which opens into the pressure change line 172.
Furthermore, an adjustable flow restrictor 238 may be arranged in the ventilation line 198, preferably downstream of the ventilation valve 236.
The apparatus 100 further comprises a bypass line 240, which connects the evacuation line 178 directly to the treatment chamber 104.
Arranged in the bypass line 240 is a bypass valve 242, by means of which the bypass line 240 is openable or closeable.
By means of the bypass line 240, the interior space 106 of the treatment chamber 104 can be evacuated directly by means of the vacuum generator 168, in the present case by means of the vacuum pump 190, to the lower pressure value pu, for example at the beginning of the passivation process or at the beginning of a rinsing process, while circumventing the negative pressure store 224.
In this embodiment, the negative pressure stores 224 are used for reducing the pressure in the treatment chamber 104 during the pressure reduction phases of the pressure change cycles of the passivation process and/or the rinsing process.
For this purpose, during the passivation process or the rinsing process, a respective one of the negative pressure stores 224, for example the second negative pressure store 224b, is evacuated by means of the vacuum generator 168, while the respective other negative pressure store 224, for example the first negative pressure store 224a, is in fluidic connection with the interior space 106 of the treatment chamber 104 during one or more pressure reduction phases, such that a gas stream (which may be loaded with droplets of the treatment agent and/or with a vapor of the treatment agent) flows from the interior space 106 of the treatment chamber 104 into the interior space of the negative pressure store 224a.
During this phase, the first supply valve 228a is open and the first discharge valve 232a is closed.
At the same time, the second supply valve 228b is closed and the second discharge valve 232b is open, such that the gas is sucked from the second negative pressure store 224b through the evacuation line 178 and the interior space of the second negative pressure store 224b is evacuated to a pressure that is preferably below the lower pressure value pu.
Due to the cooling by means of the heat exchanger 234, a vapor of the treatment agent, in particular the passivating agent, entrained in the gas stream entering the first negative pressure store 224a in a pressure reduction phase is condensed out of said gas stream.
When the pressure in the interior space 106 of the treatment chamber 104 has been reduced to the lower pressure value pu due to the fluidic connection with the first negative pressure store 224a, the first supply valve 228a is closed and the ventilation valve 236 in the ventilation line 198 is opened, such that ambient air travels through the ventilation line 198 and the pressure change line 172 into the interior space 106 of the treatment chamber 104.
When the pressure in the interior space 106 of the treatment chamber 104 has increased to the upper pressure value po, the pressure changing apparatus 160 is switched back into the evacuation state in which the ventilation valve 236 is closed and the first supply valve 228a is open.
In this way, a plurality of pressure reduction phases can be performed by means of the first negative pressure store 224a until the pressure in the negative pressure store 224a has increased to the lower pressure value pu or to a higher pressure value, such that the interior space 106 of the treatment chamber 104 is no longer able to be evacuated through a fluidic connection with the first negative pressure store 224a.
Starting with the next pressure reduction phase, the roles of the two negative pressure stores 224a and 224b are then switched. For this purpose, the second discharge valve 232b is closed and the second supply valve 228b is opened, such that a gas stream is able to travel from the interior space 106 of the treatment chamber 104 into the second negative pressure store 224b.
At the same time, the first supply valve 228a is closed and the first discharge valve 232a is open, such that the gas collected in the first negative pressure store 224b and the condensate collected in said gas is able to be discharge through the first discharge line 230a and the evacuation line 178 to the separator 166 and to the vacuum generator 168.
In all other respects, the second embodiment of an apparatus 100 depicted in
A third embodiment depicted in
In the embodiment depicted in
A gas connection 250 of the working cylinder 244 opens into a receiving space 252 of the working cylinder 244, the volume of which is variable by displacing the piston 246.
The gas connection 250 is connected to the pressure change line 172 by way of a supply line 254 in which a supply valve 256 is arranged.
Arranged in the supply line 254 is a first check valve 258, which prevents fluid from flowing from the working cylinder 244 back into the interior space 106 of the treatment chamber 104.
Furthermore, the gas connection 250 of the working cylinder 244 is connected to the storage container 122, preferably to the dirty region 130 of the storage container 122, by way of a discharge line 260.
Arranged in the discharge line 260 is a second check valve 262, which prevents fluid from flowing from the storage container 122 back into the working cylinder 244.
The piston 246 in the working cylinder 244 can be retracted up to a separating wall 264 in order to increase the volume of the receiving space 252 in the working cylinder 244.
On the side of the separating wall 264 facing away from the receiving space 252, the piston 246 is provided with a collar 266, which is able to be acted upon with a gaseous or liquid actuating fluid from its two different sides, such that the piston 246 is pneumatically or hydraulically displaceable.
The portion of the working cylinder 244 containing the receiving space 252 is preferably coolable by means of a heat exchanger 268, which can be supplied with a coolant by a coolant line 270.
As a result of the cooling by means of the heat exchanger 268, a vapor of the treatment agent, in particular the passivating agent, which is entrained by the gas that has traveled from the interior space 106 of the treatment chamber 104 into the receiving space 252, can be condensed out.
During a pressure reduction phase of the pressure change cycles in the treatment chamber 104, the receiving space 252 in the working cylinder 244 is enlarged by displacing the piston 246 (upward in
In a subsequent pressure increase phase, the ventilation valve 298 connected to the ventilation line 198 is open, while the evacuation valve 296 and the supply valve 256 are closed.
Thus, in this pressure increase phase, the interior space 106 of the treatment chamber 104 is ventilated by the ventilation line 198 and the pressure change line 172.
The piston 246 is displaced along the displacement direction 248 (upward in
Here, the gas and condensate collected in the receiving space 252 is transferred through the discharge line 260 into the storage container 122, preferably into its dirty region 130.
In this embodiment of an apparatus 100 for passivating workpieces 102, the vacuum generator 168, which in this case is configured, e.g., as a vacuum pump 190, and the separator 166 are optional and may serve, in particular, to evacuate the interior space 106 of the treatment chamber 104 from the atmospheric pressure to the lower pressure value pu at the beginning of a passivating process and/or a rinsing process.
In all other respects, the third embodiment of an apparatus 100 depicted in
In a fourth embodiment, schematically depicted in
This system has a plurality of treatment stations, for example a cleaning station 272, an intermediate rinsing station 274, a first passivation station 276, a second passivation station 278, a first rinsing station 280, a second rinsing station 282, a third rinsing station 284, and a drying station 286.
The stations 272 to 286 are preferably arranged substantially linearly one behind the other along a transport direction 288.
Each of the treatment stations is filled with a bath 290 of a treatment agent corresponding to the respective function, for example a cleaning liquid, a rinsing liquid, or a passivating agent.
By means of a transport apparatus 292, the workpieces 102 are transportable from treatment station to treatment station, immersible in the respective bath 290 of a treatment agent, and removable from the bath 290 after completion of the treatment in the respective bath 290.
The transport apparatus 292 may be provided with a rotating apparatus 294 for rotating a workpiece 102 arranged thereon.
Likewise, individual treatment stations or a plurality of the treatment stations may each be provided with a workpiece receptacle 212, which is rotatable, preferably about a horizontal rotational axis, by means of a rotating apparatus (not depicted).
At least the passivation stations 276 and 278 are provided with a lid (not depicted in
Because a plurality of passivation stations 276, 278 are provided in the passivation system, the throughput for the passivation of workpieces 102 can be increased.
Here, provision may be made that the entire passivation process is performed in only one of the passivation stations 276 and 278 and the workpieces 102 to be passivated are introduced into a respective one of these passivation stations 276, 278 alternatingly.
Alternatively hereto, provision may also be made that each of the workpieces 102 to be passivated is introduced into a plurality of passivation stations 276, 278 one after the other, such that a plurality of passivation processes are performed on each workpiece 102 in different passivation stations 276, 278.
Here, the bath 290 of the passivation station 276 into which the workpiece 102 is first introduced is most heavily contaminated and the bath 290 of the passivation station 278 into which the workpiece 102 is last introduced is least contaminated. As a result, the surface quality and the cleanliness of the passivated workpiece 102 are further improved.
For processing the passivating agent, the passivating agent can be conveyed in a cascade partially from the passivation station 278 located further back in the treatment sequence into the passivation station 276 located further ahead in the treatment sequence.
The passivating agent from the passivation station 276 located first in the treatment sequence is partially discarded.
In the multi-stage passivation process described above, the treatment temperature and/or the concentration of the acid in the respective passivating agent may be different in the different passivation stations 276, 278.
Here, it is particularly favorable if in the passivation station 278 located last in the treatment sequence the concentration of the acid in the passivating agent is lowest, such that less acid is carried over into the subsequent rinsing station 280.
For example, provision may be made that the treatment temperature in the passivation station 276 located further ahead in the treatment sequence is at least 10% higher and/or at most 20% higher than the treatment temperature in the passivation station 278 located further back in the treatment sequence (the percentages hereby referring to the absolute temperature of the respective passivating agent).
Furthermore, it is favorable if the concentration of the acid in the passivating agent in the passivation station 276 located further ahead in the treatment sequence is at least 50% higher than the concentration of the acid in the passivating agent in the passivation station 278 located further back in the treatment sequence and/or if the concentration of the acid in the passivating agent in the passivation station 276 located further ahead in the treatment sequence is at most 80% higher than the concentration of the acid in the passivating agent in the passivation station 278 located further back in the treatment sequence.
Alternatively to the configuration as an in-line immersion system, a system for passivating workpieces 102 may also be configured as a single-chamber system with a plurality of storage containers for the different treatment agents such as, e.g., rinsing agent and passivating agent with different concentrations of acids.
An equalization of evaporation losses of the baths 290 in the passivation stations 276 and 278 can be equalized by the addition of rinsing liquid from one of the subsequent rinsing stations 280, 282, or 284. These rinsing liquid are already enriched with passivating agent in low concentration due to carryover of passivating agent from one of the passivation stations 276 and/or 278 and are already tempered to the desired treatment temperature. By adding rinsing liquid from one of the rinsing stations 280, 282 or 284 to the bath 290 of passivating agent in one of the passivation stations 276 or 278, an energy savings and a saving of resources such as water and acid for the passivating agent is thus achieved.
The process stations of the apparatus 100 according to the embodiment depicted in
In all other respects, the fourth embodiment of an apparatus 100 depicted in
A fifth embodiment, depicted schematically in
Each of the treatment chambers 104 is connected by way of a respective evacuation valve 296 to an evacuation line 178 leading to the separator 166 and is connected by way of a respective ventilation valve 298 to a ventilation line 198.
In the treatment chambers 104, a respective passivating process or a respective rinsing process may be performed on a workpiece 102, or a passivating process is performed in one treatment chambers 104 and a rinsing process is performed in the respective other treatment chamber 104.
In all these cases, a cyclical pressure change operation is performed in each of the two treatment chambers 104, the pressure reduction phases and the pressure increase phases of these cyclical pressure change operations being phase-shifted against one another such that the pressure in a respective one of the treatment chambers 104 is lowered by evacuating by means of the vacuum generator 168, while the pressure in the respective other treatment chamber 104 is increased by ventilation by way of the respective ventilation valve 298.
The treatment chambers 104 are thus alternatingly brought into fluidic connection with the separator 166 and the vacuum generator 168 by opening and closing their respective evacuation valves 296 in a time-offset manner. The vacuum generator 168 therefore always only has to evacuate one of the treatment chambers 104, such that a cyclical pressure change in both treatment chambers 104 is made possible by means of only one single vacuum generator 168.
In all other respects, the fifth embodiment of an apparatus 100 depicted in
Schematically depicted in
The treatment chamber 104 comprises a tank 110, which is fillable with a bath 290 of a treatment agent, in particular a passivating agent.
At its upper rim, the tank 110 is provided with a suction channel 300, which is connected to the respective pressure change line 172 of the corresponding apparatus 100.
The suction channel 300 may have, e.g., a rectangular, preferably substantially square, cross-section.
The interior space of the suction channel 300 is connected to the interior space 106 of the treatment chamber 104 by way of a through-opening 302.
The through-opening 302 may be configured, e.g., as a gap extending in a longitudinal direction.
The through-opening 302 may be closeable by means of a cover 304.
The cover 304 may be pivotably arranged on a wall 306 of the suction channel 300 by means of a hinge.
The treatment chamber 104 may further comprise a guide 308 on which the lid 116 of the treatment chamber 104 is displaceably guided, preferably in the horizontal direction.
Provision may hereby be made that a lower rim region 310 of a substantially vertically oriented side wall 312 of the lid 116 is accommodated in an interior space 314 of the guide 308.
The guide 308 may have a substantially U-shaped cross-section, for example.
In order to perform a validation of the passivation method, which is performed with any one of the embodiments described above of an apparatus 100 for passivating workpieces 102, a test piece 316 can be used, which is depicted in a schematic longitudinal section in
The test piece 316 is affixed to a point of a goods carrier receiving the workpiece 102 to be passivated, which is representative for the effectiveness testing.
The geometry of the test piece 316 is selected such that it corresponds to the most difficult to passivate workpiece 102 of the workpiece variants of a production line that are to be passivated by means of the respective apparatus 100 for passivating workpieces 102.
For this purpose, the test piece 316 is preferably provided with at least one cavity 318 and with at least one capillary 320, preferably a plurality of capillaries 320.
A measuring strip 322 is arranged in at least one of the cavities 318 and/or in at least one of the capillaries 320.
The measuring strip 322 is provided with a sensitive surface 324 that reacts to the passivating agent (so-called “smart surface”).
The sensitive surface 324 of the measuring strip 322 changes due to contact with the passivating agent.
For example, the measuring strip 322 may be a pH value measuring strip, which changes its color through contact with the passivating agent.
Alternatively or in addition hereto, provision may also be made that the measuring strip comprises a stainless steel material, for example the stainless steel material with the workpiece number 1.4401. The passivating effect exerted on the stainless steel material by the passivating agent can be measured according to one of the methods described in the standard ASTM A 967 or alternatively by XPS measurement (x-ray photoelectron spectroscopy) of the chromium content and the iron content on the surface of the stainless steel material.
The effectiveness of the passivation method is tested after completion of the passivation treatment. For this purpose, the measuring strip 322 is removed from the test piece 316, and the change of the sensitive surface 324 of the measuring strip 322 is evaluated by means of a suitable testing method.
In order to be able to insert the measuring strip 322 into a cavity 318 or into a capillary 320 of the test piece 316 in a simple manner, the test piece 316 is preferably of multi-part configuration, wherein at least two parts of the test piece 316 abut against one another along an abutment surface 326 when the test piece 316 is composed of a plurality of parts.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102022108314.4 | Apr 2022 | DE | national |
This application is a continuation of international application number PCT/EP2023/058695 filed on 3 Apr. 2023 and claims the benefit of German application number 10 2022 108 314.4 filed on 6 Apr. 2022. The present disclosure relates to the subject matter disclosed in international application number PCT/EP2023/058695 of 3 Apr. 2023 and German application number 10 2022 108 314.4 of 6 Apr. 2022, which are incorporated herein by reference in their entirety and for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2023/058695 | Apr 2023 | WO |
| Child | 18907247 | US |
