Patent Publication Number: US-11638936-B2

Title: Cleaning device

Description:
TECHNICAL FIELD 
     This description generally relates to a cleaning method and a cleaning device. In particular, the description relates to a cleaning method by means of a cleaning device which has a cleaning chamber and a nozzle tube arranged in the cleaning chamber, said nozzle tube being able to move on a circulation track about a workpiece carrier with at least one workpiece, and a corresponding cleaning device. 
     BACKGROUND 
     The nozzle tube with this type of cleaning device comprises at least one nozzle which is directed toward the workpiece carrier and, by means of said nozzle, a cleaning liquid, such as, for example, a surfactant-containing cleaning liquid based on water, can be discharged under pressure onto the at least one workpiece being held by the workpiece carrier. Such a cleaning device is known, for example, from EP 0 507 294 B1 or from DE 102 16 285 B4. 
     As described in DE 10 2004 046 802, the nozzle tube of such a cleaning device may be implemented such that the nozzle can be pivoted about a longitudinal axis of the nozzle tube. An angle of impact of a cleaning jet discharged onto the workpiece through the nozzle can hereby be varied, whereby particularly efficient cleaning can be achieved. 
     SUMMARY 
     The object upon which the invention is based is provision of an improved cleaning method by means of a cleaning device, having a pivotable nozzle, and provision of a corresponding cleaning device. 
     The method comprises the cleaning of at least one workpiece, which is being held by a workpiece carrier in a treatment container, by means of at least one nozzle which discharges a cleaning jet directed onto the workpiece. The cleaning comprises the specifying of a rotational speed of the workpiece carrier and a circulation speed of the at least one nozzle on a circulation track about the workpiece carrier, rotating of the workpiece carrier at the specified rotational speed, and moving of the at least one nozzle at the specified circulation speed about the workpiece carrier, and pivoting of the at least one nozzle about a pivoting axis extending parallel to an axis of rotation of the workpiece carrier such that a specified point on the surface of the workpiece is impacted repeatedly by the cleaning jet at a respectively different angle within a specified timeframe. 
     The cleaning device comprises a treatment container; a workpiece carrier arranged in the treatment container, said workpiece carrier being designed to hold at least one workpiece; at least one nozzle; and a pivoting device. The nozzle is designed to discharge a cleaning jet directed onto the workpiece carrier and is mounted such that the nozzle can move on a circulation track about the workpiece carrier and that it can pivot about a pivoting axis extending parallel to the axis of rotation of the workpiece carrier. To this end, the pivoting device is designed to pivot the at least one nozzle. In addition, the cleaning device comprises a controller which is designed to control a circulating movement of the at least one nozzle on the circulation track and a pivoting movement of the at least one nozzle such that a specified point on a surface of the workpiece can be impacted repeatedly by the cleaning jet at a respectively different angle within a specified timeframe. 
     Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Examples are explained in the following by means of figures. The figures are intended to illustrate certain principles to the extent that only those features necessary for understanding these principles are shown. The figures are not true-to-scale. The same reference numerals refer to equivalent features in the figures. 
         FIGS.  1 A and  1 B  show a partial cross-section of a treatment device having a treatment container, a nozzle device, and a workpiece carrier, in two different sectional planes; 
         FIG.  2    illustrates the position of a liquid jet being discharged through a nozzle of the nozzle device relative to a surface of a workpiece, with different angle settings of the nozzle; 
         FIGS.  3 A- 3 C  illustrate the creation of a point of intensive cleaning (hotspot) on a surface of the workpiece at different points in time during the cleaning process; 
         FIGS.  4 A- 4 D  schematically show an example of a pivoting device for pivoting a nozzle tube of the nozzle device; and 
         FIG.  5    illustrates cleaning jets in the context with five different hotspots. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the attached figures which form a part of the description. Of course, the features of the individual figures can be combined with one another unless indicated otherwise. 
       FIGS.  1 A and  1 B  each schematically show a cleaning device for cleaning one of several workpieces, wherein  FIG.  1 A  shows the device in a first sectional plane I-I extending parallel to an axis of rotation A-A, and  FIG.  1 B  shows the device in a second sectional plane II-II extending perpendicularly to axis of rotation A-A. With reference to  FIGS.  1 A and  1 B , the device comprises a treatment container  1 , a nozzle device  2  arranged in the treatment container  1 , said nozzle device having at least one nozzle  4  and a workpiece carrier  3  arranged in the treatment container  1 , said workpiece carrier intended for holding at least one workpiece  5 . Only the treatment container  1  is shown in cross-section in  FIGS.  1 A and  1 B ; the remaining parts are shown in the respective side view. 
     The treatment container  1  may be designed to be pressure-resistant in order to enable creation of a vacuum during a cleaning process and may have a closable or controllable discharge (not shown) for a cleaning medium in order to enable the production of a cleaning bath surrounding the at least one workpiece  5 , said cleaning bath being situated in the treatment container  1 . 
     The workpiece  5  is only shown schematically in  FIGS.  1 A and  1 B . This workpiece  5  may be an individual workpiece which is directly held by the workpiece carrier  3 . Alternatively, a plurality of workpieces (in bulk) may be in a workpiece basket which is held by the workpiece carrier  3 . Such a workpiece basket secures the workpieces by keeping them from falling out and is permeable to liquid in order to enable cleaning of the workpieces. The term “workpiece” in the following thus characterizes an individual workpiece or several individual workpieces which is/are held directly by the workpiece carrier  3 , or a plurality of workpieces which are held by a workpiece basket, which is held by the workpiece carrier  3 . 
     The nozzle device  2  comprises at least one nozzle tube  22  with at least one nozzle  4  which has a nozzle outlet directed onto the workpiece carrier  3  and/or onto the workpiece  5 . The nozzle device  2  is mounted such that the at least one nozzle  4  can move on a circulation track about the workpiece carrier  3 . To this end, the nozzle device  2  has a first shaft  21  which is mounted rotatably such that it can rotate about an axis of rotation A-A. The nozzle  4  is arranged in a direction perpendicular to axis of rotation A-A spaced apart from axis of rotation A-A and/or the first shaft  21  and thus mounted opposite the first shaft  21  such that the nozzle  4  moves on a (circular) circulation track about rotation of axis A-A and the workpiece carrier  3  when the first shaft  21  rotates about axis of rotation A-A. 
     The workpiece carrier  3  may be stationary. As is shown in  FIGS.  1 A and  1 B , the workpiece carrier  3  may also be implemented, however, such that it can rotate about axis of rotation A-A. In this case, the workpiece carrier  3  has a second shaft  31  which is mounted rotatably such that it can rotate about axis of rotation A-A. 
     In the example shown in  FIGS.  1 A and  1 B , the at least one nozzle  4  is arranged on a nozzle tube  22 . The nozzle tube extends substantially parallel to axis of rotation A-A and is connected to the first shaft  21  by means of a supply tube  23 . The first shaft  21 , the supply tube  21 , and the nozzle tube  22  are hollow and form a liquid channel, by means of which cleaning liquid from a reservoir  24  (schematically shown) arranged outside of the treatment container  1  can reach the at least one nozzle  4 . The reservoir  24  is connected to the shaft  21  via a line  25  and a coupling piece  26  in order to supply cleaning fluid to the shaft  21 . Optionally, a pump (not shown) is arranged in the outer supply line  25 , said pump being used to subject the cleaning fluid to a desired pressure. Such an arrangement with a reservoir  24 , an outer supply line  25 , a coupling piece  26 , and a (hollow) shaft is generally known to the extent that further embodiments with respect to this are superfluous. 
     With the device according to  FIG.  1 A , the first shaft  21  of the nozzle device  2  and the second shaft  31  of the workpiece carrier  3  are guided out of the treatment container  1  on opposite sides at respective openings  11 ,  12 . However, it is also possible to guide the first shaft  21  for the nozzle device  2  and the second shaft  31  for the workpiece carrier  3  out jointly on one side of the treatment container  1  via one of the openings  11 ,  12  and to omit the other one of the openings. In this case, the first shaft  21  may be designed as a hollow shaft in which the second shaft  31  is rotatably mounted, wherein a channel for the cleaning liquid may be formed along the second shaft  31 , in the first shaft  21 . This type of implementation of the first end of the second shaft  21 ,  31  is basically known and described, for example, in the previously mentioned EP 0 507 294 B1 to the extent that further embodiments regarding this are superfluous. 
     As previously mentioned, the nozzle device comprises at least one nozzle tube  22  with at least one nozzle  4 . As is shown in  FIG.  1 A , several nozzles  4  may be provided on the nozzle tube  22 , said nozzles being arranged apart from one another in a longitudinal direction of the nozzle tube  22 . The “longitudinal direction” of the nozzle tube  22  is a direction of the nozzle tube  22  extending parallel to axis of rotation A-A. The nozzles  4  are located, for example, on an outer surface of the nozzle tube  22  and are attached at or in holes of the nozzle tube  22 . Each of the nozzles  4  has a nozzle outlet, which is designed to discharge cleaning liquid in the direction of the workpiece  5 , said cleaning liquid being supplied to the respective nozzle  4  via the channel formed by the first shaft  21 , the supply tube  23 , and the nozzle tube  22 . The nozzles  4  may be implemented in any conventionally known manner According to one example, it is provided to omit the separate nozzles arranged on the nozzle tube  22  and to form the nozzles  4  through holes in the nozzle tube  22 . 
     With reference to  FIGS.  1 A and  1 B , the nozzle assembly may comprise several nozzle tubes  22  of the previously explained type, wherein each of these nozzle tubes  22  has at least one nozzle  4 . For illustration purposes only, the example shown in  FIG.  1 B  shows four such nozzle tubes  22  which are arranged at an angle distance of 90° relative to one another in relation to axis of rotation A-A. The provision of four nozzle tubes  22 , however, is only an example. According to a further example, the nozzle assembly  2  comprises two oppositely disposed nozzle tubes  22  or even only one nozzle tube  22 . 
     The first shaft  21  of the nozzle assembly  2  and, optionally, the second shaft  31  of the workpiece carrier  3  are driven, independently of one another, by a respective motor: a first motor  6  which drives the first shaft  21  of the nozzle assembly  2  and a second motor  7  which drives the second shaft  31  of the workpiece carrier  3 . A circulation speed of the nozzle tube  22  about the workpiece carrier  3  (and the at least one workpiece  5  thereby being held) and a rotational speed of the workpiece carrier  3  and of the workpiece  5  can hereby be adjusted independently of one another, wherein the rotational speed of the workpiece carrier  3  may be zero or not equal to zero. The two motors  6 ,  7  are actuated by means of a controller  8 , which specifies the rpm of the motors  6 ,  7 , wherein the rpm of the first motor  6  determines the circulation speed of the nozzle tube  22  about the workpiece carrier  3  and the workpiece  5 , and the rpm of the second motor  7  determines the rotational speed of the workpiece carrier  3  and of the workpiece  5 . 
     The at least one nozzle tube  22  with the at least one nozzle  4  is pivotably mounted such that the nozzle tube  22  can pivot about a longitudinal axis B-B, which extends substantially parallel to axis of rotation A-A, within a specified pivot range. This is explained by means of  FIG.  2    in the following. 
       FIG.  2    schematically shows a cross-section through the nozzle tube  22  in a sectional plane extending perpendicular to longitudinal axis B-B.  FIG.  2    additionally shows a cross-section through the workpiece  5 , which is cylindrical in this example merely for illustration purposes. The workpiece carrier  3  is not shown in  FIG.  2   . 
     The pivot range of the nozzle tube  22  according to one example comprises a position of the nozzle tube  22  in which the outlet of the nozzle  4  points toward axis of rotation A-A. A nozzle jet  42 , which is discharged through the nozzle  4  in this position of the nozzle tube  22 , is represented by a dashed-and-dotted line in  FIG.  2   . This position of the nozzle tube  22  is also characterized as the zero position  41   0  in the following. According to one example, it is additionally provided that the nozzle tube  22  can be pivoted and/or deflected relative to the zero position  41   0  on both sides, wherein the nozzle tube specifies a respective endpoint  41   1 ,  41   2  in both directions. Cleaning jets which are discharged through the nozzle  4  when the nozzle tube  22  is in the first and second endpoint  41   1 ,  41   2  are likewise indicated by dashed-and-dotted lines in  FIG.  2   . 
     An angle range Δγ between the first endpoint  41   1  and the second endpoint  41   2  is characterized in the following as a pivot range of the nozzle tube  22 . This pivot range, for example, is between 10° and 80°, particularly between 30° and 70°. According to one exemplary embodiment, the first end position  41   1  and the second end position  41   2  are arranged symmetrical to the zero position  41   0  to the extent that the nozzle tube  22  can pivot an equal distance in both directions, starting from the zero position  41   0 , i.e. a first angle distance γ1 between the zero position  41   0  and the first end position  41   1  is equal to a second angle distance γ2 between the zero position  41   0  and the second end position  41   2 . However, this is merely an example. According to another example, the end positions  41   1 ,  41   2  are arranged asymmetrical to the zero position  41   0  to the extent that the nozzle tube  22  can pivot an unequal distance, starting from the zero position  41   0 , in the direction of the first end setting  41   1  and in the direction of the second end setting  41   2 . 
     According to one example, the nozzle tube  22  is actuated during the cleaning process to the extent that the nozzle tube  22  pivots cyclically from the first end position  41   1  to the second end position  41   2  and back to the first end position  41   1  and, in doing so, passes over the respective zero position  41   0 . Such type of movement is referred to as a complete pivoting movement in the following. An impact angle, at which the cleaning jet  42  impacts a surface  51  of the workpiece  5 , and also a speed of the cleaning jet relative to the workpiece surface  5  hereby repeatedly change. An especially efficient cleaning of the workpiece  5  can hereby be achieved. The change of the impact angle and the speed of the cleaning jet as compared to the workpiece surface  51  are explained in greater detail in the following. According to one example, it is additionally provided that an integer number n of complete pivoting movements are executed by the nozzle tube  22  per revolution of the nozzle tube  22  about the workpiece carrier  3 . This number n, for example, is between 1 and 7, particularly between 5 and 5. 
     According to one example, it is provided to synchronize a circulating movement of the nozzle tube  22  about the workpiece carrier  3  and a pivoting movement of the nozzle tube  22  to one another such that a specified point on the surface  51  of the workpiece  5  is impacted repeatedly by the cleaning jet  42 , at a respectively different angle, within a specified timeframe. The specified timeframe in this case, for example, is between 1 minute (min) and 10 minutes, particularly between 1 minute and 10 minutes. 
     With reference to  FIG.  2   , it should be assumed that the workpiece surface  51  moves at a speed v 5  in a first direction relative to the nozzle tube  22 . This means that a certain point  5  of the workpiece surface moves at speed v 5  relative to the nozzle tube  22 . This is achieved, for example, in that (a) the second shaft  31 , which drives the workpiece  5 , rotates in a first direction of rotation, and the first shaft  21 , which determines the circulation speed of the nozzle tube  22  about the workpiece  5 , rotates in a second direction of rotation opposite the first direction of rotation or that (b) the second shaft  31  rotates in the first direction of rotation and the first shaft  21  likewise rotates in the first direction of rotation, but at a lower rotational speed than the second shaft  31 . The speed v 5  at which the surface  51  of the workpiece  5  moves relative to the nozzle tube  22  would be zero (0) when both shafts  21 ,  31  are stopped or have the same rotational speed and the same direction of rotation. 
     If the cleaning jet  42  is directed statically onto the surface of the workpiece  5 , i.e. without a pivoting movement of the nozzle tube  22 , the speed at which the cleaning jet is guided along the surface of the workpiece  5  corresponds to the relative speed v 5  of the workpiece surface  51  relative to the nozzle tube  22 . When the nozzle tube  22  is executing a pivoting movement, a speed of the nozzle jet relative to the workpiece surface  51  resulting from the pivoting movement and the relative movement of the workpiece surface  51  relative to the nozzle tube  22  overlap to the extent that the speed at which the cleaning jet is guided along the workpiece surface  51  varies. Moreover, an impact angle at which the cleaning jet  42  impacts the workpiece surface  51  varies. 
     In order to ensure that the cleaning jet passes over a certain point of the surface  51  repeatedly within a specified time and does so at a respectively different impact angle, it may be provided to tightly couple the pivoting movement of the nozzle tube  22  with the circulating movement of the nozzle tube about the workpiece carrier to the extent that an angle position γ of the nozzle tube  22  is uniquely assigned to each position of the nozzle tube  22  on the circulation track, and to suitably establish a rotational speed ω31 of the shaft  31  of the workpiece carrier  3  and a rotational speed ω21, which determines the circulation speed of the nozzle tube  22  about the workpiece carrier  3 , of the shaft  21  of the nozzle device  2 , and to maintain the respectively specified value during the specified timeframe. How often the cleaning jet  42  passes over a certain point in this case is dependent on the specified timeframe, which is characterized in the following also as the cleaning time T R , the rotational speed ω31 of the workpiece  5  through the workpiece carrier  3 , and the rotational speed ω21 of the shaft  21  of the nozzle device, which is characterized in the following also as circulation speed. An example of this is explained in the following. 
     Example 1 
     With reference to this, it should be assumed that the workpiece  5  rotates through the workpiece carrier  3  at a rotational speed ω31=5 rpm (=10π/60 s −1 ) such that the first shaft  21  rotates opposite the second shaft  31  at a rotational speed ω21=−2 rpm (=4π/60 s −1 ) such that n=5 full pivoting movements are completed per revolution of the nozzle tube and that the specified timeframe (the cleaning time T R ) is 1 minute. In this case, the workpiece  5  rotates relative to the nozzle tube  22  at a rotational speed of 7 rpm (=14π/60 s −1 ), which corresponds to the difference ω31−−ω21 between the two rotational speeds. Ten full pivoting movements of the nozzle tube  22  are completed per minute (occurring in the two revolutions of the nozzle tube). The same pivot state of the nozzle tube  22  repeats itself every 1/10 min in this example, wherein each time when the same pivot state is repeated, a different point of the surface  51  is impacted by the cleaning jet  42 . 
     Each “pivot state” is determined by a pivot angle of the nozzle tube  22  and a pivoting device. During each complete pivoting movement of the nozzle tube  22 , each pivot angle (with the exception of the two angles in the reversal points of the pivoting movement) occur twice: once when the nozzle tube  22  pivots in one direction and once again when the nozzle tube pivots back. Because the pivot directions of the two pivot states in which the nozzle tube  22  has the same pivot angle differ, the workpiece surface is substantially impacted at the same angle in these two pivot states; however, the speeds at which the cleaning jet  42  passes over the workpiece surface  51  differ, as is explained in greater detail below. The fact that each time a pivot state of the nozzle to  22  is repeated a different point of the surface  51  is impacted by the cleaning jet  42  means that each time the cleaning jet  42  impacts a certain point on the surface  51 , said point is impacted at a different angle and/or the cleaning jet passes over at a different speed. 
     Between two repetitions of the pivoting movements, the workpiece  5  in the above example rotates by 14π/10=1.4π relative to the nozzle tube  22  to the extent that two points, which are impacted by the cleaning jet  42  in two sequential pivoting movements during the respectively same pivot state of the nozzle tube  22 , are disposed at positions on the surface  51  which are spaced apart from one another by an angle distance 1.4π. In addition, the points in this example do not repeat within the specified timeframe, as is explained in the following. 
     To this end, it should be assumed that the surface  51  of the workpiece forms a cylindrical coordinate system, in which each point is determined by a particular angle which is between 0 and 2π. In addition, it should be assumed that a characterizes the angle position of a point on the surface, said point being impacted by the cleaning jet  42  during a first pivoting movement of the nozzle tube in a particular pivot state, wherein the points on the surface  51  differ, said points being impacted by the cleaning jet  42  during the first complete pivoting movement of the nozzle tube  22  in different pivot states. In general, the points on the surface  51  are thus impacted by the cleaning jet  42 , during a particular pivot state, at angle positions of the workpiece  5 , which are specified by 
                         a   +       (     i   ·       14   ⁢   π     10       )     ⁢        mod   ⁢          (     2   ⁢   π     )                   for   ⁢         0     ≤   i   ≤   9     ,                 (   1   )               
wherein mod(.) characterizes the modulo operation, and α is the angle position of the point at which the particular pivot state first occurs during cleaning. Thus, sequential surface points situated at the following angle positions of the workpiece  5  are impacted by the cleaning jet in the same pivot state: α;
 
α+1.4π; α+0.8π; α+0.2π; α+1.6π; α+1π; α+0.4π; α+1.8π; α+1.2π; α+0.6π.
 
During continuation of the cleaning process, these positions would be repeated to the extent that the same point would be impacted repeatedly at the same impact angle. In relation to the workpiece surface, the positions which are impacted at the same impact angle are equidistant and separate from one another by an angle distance of 0.2π, respectively. Of course, smaller angle distances can also be achieved in order to clean the workpiece more consistently by means of a suitable selection of the rotational speeds ω21, ω31, the number n of complete pivoting movements per revolution of the nozzle tube  22 , and the cleaning time. With a longer cleaning time, the rotational speeds ω21, ω31 can be adapted to the extent that the angle distance of points lying next to one another on the surface is reduced, said points being impacted at the same impact angle. Two further examples are provided below.
 
     Example 2 
     n=4; T R =2 min; ω31: 2.5 rpm; ω21: −4 rpm 
     In this case, 32 complete pivoting movements (4 per revolution with 8 revolutions) occur during the cleaning time. The relative speed of the workpiece  5  relative to the nozzle tube  22  is 6.5 rpm, and positions of the workpiece which are impacted by the cleaning jet in a certain pivot state of the nozzle tube  22  lie at positions which are given by 
     
       
         
           
             
               
                 
                   
                     
                       
                         
                           a 
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                               ( 
                               
                                 i 
                                 · 
                                 
                                   
                                     26 
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                                   32 
                                 
                               
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                             ⁢ 
                                
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                                     13 
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                                   16 
                                 
                               
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                             ⁢ 
                                
                             mod 
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                               ( 
                               
                                 2 
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                           for 
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                           0 
                         
                         ≤ 
                         i 
                         ≤ 
                         31. 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     Example 3 
     n=4; T R =3; ω31: 2.666 rpm; ω21: −5 rpm 
     In this case, 60 complete pivoting movements (4 per revolution with 15 revolutions) occur during the cleaning time. The relative speed of the workpiece  5  relative to the nozzle tube  22  is 7.666 rpm, and positions of the workpiece which are impacted by the cleaning jet in a certain pivot state of the nozzle tube  22  lie at positions which are given by 
     
       
         
           
             
               
                 
                   
                     
                       
                         
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                                     23 
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                                   16 
                                 
                               
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                             ⁢ 
                                
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                         59. 
                       
                     
                   
                 
               
               
                 
                   ( 
                   3 
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     In general, positions of the workpiece which are impacted by the cleaning jet in a particular pivot state of the nozzle tube  22  are given by: 
                         a   +       (     i   ·           (       ω   ⁢   3   ⁢   1     -   ω21     )     ·     T   R     ·   2     ⁢   π       n   ·       ❘   &#34;\[LeftBracketingBar]&#34;     ω21     ❘   &#34;\[RightBracketingBar]&#34;       ·     T   R           )     ⁢        mod   ⁢          (     2   ⁢   π     )                   for   ⁢         0     ≤   i   ≤       (     n   ·       ❘   &#34;\[LeftBracketingBar]&#34;     ω21     ❘   &#34;\[RightBracketingBar]&#34;       ·     T   R       )     -   1       ,                 (   4   )               
wherein the individual parameters, particularly the two angular velocities, are selected such that the values differ by pairs to the extent that the no two values are equal. In this case, an especially efficient cleaning of the workpiece  5  is achieved.
 
As previously explained, the nozzle  4  has a relative speed v 5  relative to the surface  51  of the workpiece  5  due to the circulation speed ω21 (and possibly the rotational movement of the workpiece  5 ). In one example, it is additionally provided that this relative speed v 5  and the pivot speed associated with the pivoting of the at least one nozzle  4  are synchronized with one another to the extent that a speed v REL , at which the cleaning jet  42  moves over a specified point at least once, is less than 50%, less than 30%, or less than 10% of the relative speed v 5 . This is likewise explained by means of  FIG.  2   .
 
In the following, v 4  characterizes the speed at which the cleaning jet moves relative to the workpiece surface  51  due to the pivoting movement of the nozzle tube  22 . The direction in which the cleaning jet moves relative to the workpiece surface  51  and also relative to axis of rotation A-A in this case depends on the current pivot direction of the nozzle tube  22 . Merely for explanatory purposes, it should be assumed that the cleaning jet moves relative to the workpiece surface  51  in the first direction when the nozzle tube  22  pivots away from the first endpoint  41   1  toward the second endpoint  41   2 , and the nozzle jet moves relative to the workpiece surface  51  in an opposite second direction when the cleaning jet pivots from the second end position  41   2  back to the first end position  41   1 . If the cleaning jet moves relative to the workpiece surface  51  in the same direction in which the workpiece surface  51  moves relative to the nozzle tube  22 , the relative speed v REL  of the cleaning jet relative to the workpiece surface  51  is temporarily less than would be the case with a static cleaning jet at the same relative speed v 5  of the workpiece surface relative to the nozzle tube. This relative speed v REL  is given by the difference v 5 −v 4  between the two speeds v 5  and v 4 .
 
     In the ideal case, the cleaning jet is even temporarily stopped in place over a point on the workpiece surface  51 , wherein the impact angle of the cleaning jet changes over time Such a “stoppage” of the cleaning jet over a point on the workpiece surface  51  ensures a particularly intensive cleaning of the respective point on the surface due to the longer time that this point is impacted with the cleaning jet  42  and due to the changing impact angle in this case. Such a point is characterized in the following as an intensive cleaning point or hotspot. The development of such an intensive cleaning point during a cleaning process is explained by means of  FIGS.  3 A to  3 C  in the following. 
       FIGS.  3 A- 3 C  schematically illustrate the position of a certain point P 5  on the workpiece surface  51  at different points in time t 1 , t 2 , t 3  during the cleaning process. It should be respectively assumed that the workpiece surface  51 , and thus also point P 5  on the workpiece surface  51 , moves relative to the nozzle tube  22  at speed v 5 . This point P 5  is at a first position at the first point in time shown in  FIG.  3 A . In addition, it should be assumed that a cleaning jet  41  discharged through the nozzle  4  impacts point P 5  on the surface  51  at the first point in time t 1 , and the nozzle tube  22  pivots from the first end position  41   1  (not explicitly indicated in  FIGS.  3 A- 3 C ) to the second end position  41   2  (likewise not explicitly indicated in  FIGS.  3 A- 3 C ) to the extent that the cleaning jet  41  moves relative to the workpiece surface  51  in the first direction at speed v 4 .  FIG.  3 B  shows the arrangement at a second point in time t 2 , at which position P 5  has moved further in the first direction due to the relative movement of the workpiece surface  51  relative to the nozzle tube  22 , wherein the cleaning jet  41  has also moved further due to the pivoting movement at the workpiece surface  51 , and, with the example shown in  FIG.  3 B , that is just as far as point P 5  such that the cleaning jet  41  is quasi-stationary at point p 5 .  FIG.  3 C  shows the arrangement at a third point in time t 3 , at which point P 5  and, in the same manner, the cleaning jet  41  have moved further in the first direction to the extent that the cleaning jet  41  continues to be quasi-stationary at point P 5 . Point P 5  on the workpiece surface  51  in this case forms a hotspot, as was previously explained. If several nozzles  4  are provided along the longitudinal direction of the nozzle tube  22 , the workpiece  5  can be intensively cleaned simultaneously at several points positioned next to one another. 
     The development of such an intensive cleaning point during the cleaning process depends on various parameters, which are explained by means of  FIG.  2    in the following. For this explanation, it should again be assumed that ω31 is the rotational speed of the second shaft  31 , which puts the workpiece  5  into rotation, that ω21 is the rotational speed of the first shaft  21  causing the circulation track of the nozzle tube  22 , and that d 1  is the distance between the workpiece surface  51  and axis of rotation A-A. The relative speed v 5  of point P 5  on the workpiece surface  51  relative to the nozzle tube  22  is then given by:
 
 v 5=(ω31−ω21)· d 1  (4)
 
     The relative speed v 4  of the nozzle jet  41  in relation to the workpiece surface  51  due to the pivoting movement of the nozzle tube  22  is given by the following:
 
 v 4=ω22· d 2(γ)  (5)
 
     where ω22=dγ/dt characterizes a pivot speed of the nozzle tube  22 , and d 2 (γ) characterizes a distance between the workpiece surface  51  and axis of rotation B-B of the nozzle tube  22 , wherein this distance depends on the respective pivot angle γ. 
     As previously explained, a hotspot occurs during a timeframe in which the cleaning jet is moving in the first direction at speed v 4 , which amounts to the relative speed of the workpiece surface v 5  relative to the nozzle tube  22 , thus at least when v 4 =v 5  approximately applies, i.e. when thus the following relationship applies to the rotational and/or pivot speeds ω21, ω22, ω31: 
     
       
         
           
             
               
                 
                   
                     v 
                     ⁢ 
                     5 
                   
                   = 
                   
                     
                       
                         v 
                         ⁢ 
                         4 
                       
                       → 
                       
                         
                           
                             ω 
                             ⁢ 
                             3 
                             ⁢ 
                             1 
                           
                           - 
                           
                             ω 
                             ⁢ 
                             2 
                             ⁢ 
                             1 
                           
                         
                         
                           ω 
                           ⁢ 
                           2 
                           ⁢ 
                           2 
                         
                       
                     
                     = 
                     
                       
                         d 
                         ⁢ 
                         2 
                       
                       
                         d 
                         ⁢ 
                         1 
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
     The previous derivation is based on the idealized assumption that the workpiece  5  is cylindrical to the extent that a distance between the workpiece surface  51  and axis of rotation A-A is thus the same universally. This is typically not the case. However, the rotational speeds ω31, ω21 based on this derivation are adjusted such that an efficient cleaning method is achieved. Thus, for determining distance d 1  from the workpiece surface  51  to axis of rotation A-A and/or distance d 2  from the pivoting axis B-B to the workpiece surface  51 , an averaged workpiece surface is assumed  51  which represents an average distance of all points between the workpiece surface to be cleaned and axis of rotation A-A. 
     As explained above, the nozzle assembly  2  may be implemented such that the pivoting movement of the nozzle tube  22  is tightly coupled with the circulating movement of the nozzle tube  22  about the workpiece  5  to the extent that a particular angle position of the nozzle tube  22  is assigned to each position of the nozzle tube  22  on the circulation track, i.e. each angle position of the first shaft  21  relative to a starting point. According to one example, it is provided in this case that an integer number n of complete pivoting movements of the nozzle tube  22  are executed with each revolution of the nozzle tube  22  about the workpiece  5 , i.e. with each complete rotation of the first shaft  21 . In this case, n hotspots can be created per revolution of the nozzle tube  22 , because the nozzle jet moves n-times in the same direction as the workpiece surface  51  relative to the nozzle tube  22  due to the pivoting movement of the nozzle tube  22 . Moreover, the pivot speed of the nozzle tube  22  in this case depends directly on the rotational speed ω21 of the first shaft  21 . Time T S  of a complete pivoting movement of the nozzle tube  22  is then given by: 
     
       
         
           
             
               
                 
                   
                     
                       T 
                       S 
                     
                     = 
                     
                       
                         
                           2 
                           ⁢ 
                           π 
                         
                         
                           ω 
                           ⁢ 
                           2 
                           ⁢ 
                           1 
                         
                       
                       · 
                       
                         1 
                         n 
                       
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
           
         
       
     
     wherein the duration of a revolution of the nozzle tube  22  about the workpiece  5  is given by 2π/ω21. Time T HS , while the cleaning jet is moving in the same direction as the workpiece surface  5  relative to the nozzle tube  22  during a pivot time T S , is half of pivot time T S , thus 
     
       
         
           
             
               
                 
                   
                     T 
                     
                       H 
                       ⁢ 
                       S 
                     
                   
                   = 
                   
                     
                       π 
                       
                         ω 
                         ⁢ 
                         2 
                         ⁢ 
                         1 
                       
                     
                     · 
                     
                       
                         1 
                         n 
                       
                       . 
                     
                   
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
           
         
       
     
     T HS  determines the time during which the workpiece surface  51  and the cleaning jet are moving in the same direction, and thus the maximum time during which (theoretically) a hotspot can occur. When the pivot speed ω22 is constant, for example, the pivot speed ω22 is given by: 
                     ω   ⁢   2   ⁢   2     =         Δ   ⁢   γ       T     H   ⁢   S         =         Δ   ⁢   γ     π     ·   ω21   ·     n   .                 (   9   )               
Thus, the pivot speed is dependent on the circulation speed ω21 of the nozzle tube and the number n of hotspots to be created and increases as the circulation speed ω21 increases and as the number n of the hotspots increases.
 
     As shown in  FIG.  2   , distance d 2 (γ) between the nozzle and the workpiece surface  51  changes as a function of the angle position γ of the nozzle tube  22  such that, according to the equation (5), the relative speed v 4  of the nozzle jet relative to the workpiece surface  51  not only is dependent on the pivot speed ω22, but also on the varying distance d 2 (γ), wherein, at a constant pivot speed ω22, the relative speed v 4  increases as the distance increases and thus as the deflection of the nozzle  4  increases relative to the zero position  41   0 . 
     According to one example, it is provided that the pivot speed ω 22  is approximately constant. In an angle range of +/−15° about the zero position  41   0 , distance d 2 (γ) and thus the relative speed v 4  are approximately constant to the extent that the rotational speeds ω21, ω31 of the two shafts can be determined with consideration of equations (6) and (9), wherein d 2  in this case is the distance between the workpiece surface  51  and pivoting axis B-B in the zero position  41   0 . 
     In order to increase the angle range in which a hotspot occurs about the zero position, it is provided in one example to vary the pivot speed such that it decreases as the deflection of the nozzle relative to the zero position  41   0  decreases in order to compensate for the increasing deflection as the distance becomes greater. Thus, the pivoting movement could occur, for example, such that the nozzle tube pivots at a first pivot speed in a first pivot range γ0+Δγ1≤γ≤γ0−Δγ1, which is positioned at an angle γ0 of the zero position and pivots at a first pivot speed, and, in a second and third pivot range γ&gt;γ0+Δγ1 and γ&lt;γ0−Δγ1, which are outside of the first pivot range, at a second pivot speed which is lower relative to the first pivot speed. 
     A pivoting movement of the nozzle tube  22  coupled to the circulating movement of the nozzle tube  22  can be achieved in the most varied of ways. An example of this is shown in  FIGS.  4 A- 4 D .  FIGS.  4 A- 4 C  each show a section of the pivotable nozzle tube  22 , of the supply tube  23 , and of a pivoting device  27  coupled to the nozzle tube  22 , and  FIG.  4 D  shows a top view of a curved track  271  of the pivoting device  27 . 
     With reference to  FIGS.  4 A- 4 C , the pivoting device  27  comprises a lever assembly  272 , which is mechanically coupled to the nozzle tube  22  and then again to the curved track. The coupling of the lever assembly  272  to the curved track takes place in the example by means of rollers; however, it could take place also by means of one or more gear wheels or in another suitable manner. The unique assignment of the position on the circulation track to a pivot position of the nozzle tube is implemented with said pivoting device by means of a radial distance between the curved track  271  and the circulation track of the nozzle tube  22 , said radial distance being in relation to axis of rotation A-A. The circulation track of the nozzle tube is substantially circular and has a radius which is substantially determined by the length of the supply tube  23  and the radius of the first shaft  21 . The curved track  271  is noncircular to the extent that a radial distance between the curved track  271  and the nozzle tube  22 , or the circulation track thereof, while a revolution of the nozzle tube  22  about the workpiece  3  varies. The lever assembly  272  implements this varying distance in the form of a pivoting movement of the nozzle tube  22  such that the nozzle tube  22  pivots in one direction when the nozzle tube  22  is in a section of its circulation track in which the distance to the curved track  271  increases, and pivots in an opposite direction when the nozzle tube  22  is situated in a section of its circulation track in which the distance to the curved track  271  decreases. 
     With the curved track shown in  FIG.  4 D , there are four such curved track sections  271   1 ,  271   3 ,  271   5 ,  271   7 , in which the distance between the curved track  271  and the nozzle tube is increasingly reduced when the nozzle tube  22  is moving in the circulation track indicated by the arrow. These curved track sections  271   1 ,  271   3 ,  271   5 ,  271   7  are characterized in the following as the first curved track sections. In addition, there are four second curved track sections  271   2 ,  271   4 ,  271   6 ,  271   8 , in which the distance between the curved track  271  and the nozzle tube is increasingly increased when the nozzle tube  22  is moving in the circulation track indicated by the arrow. There is a turning point, at which the curved track has locally a minimum or a maximum distance, said turning point being situated between adjacent first and second curved track sections, wherein the nozzle tube  22  changes its pivot direction when the nozzle tube  22  passes a respective turning point. Thus, four complete pivoting movements are executed per revolution by means of the curved track shown in  FIG.  4 D . The number of pivoting movements can obviously be adjusted in almost any manner through a suitable selection of the number of the first and second curved track sections. 
     According to one example, it is provided to implement the first and second curved track sections respectively symmetrically as relates to the turning points and to arrange the cam disc such that corresponding turning points are situated equidistant from the circulation track. In this case, the individual pivoting movements at a given circulation speed always occur in the same manner, i.e. within the angle range thereof and with the same progression of pivot speed within a pivoting process, wherein said pivot speed may vary within a pivoting process. 
     The pivoting device shown in  FIGS.  4 A- 4 C  is only one of many possible examples, by means of which a coupling can be achieved between the pivoting movement of the nozzle tube  22  and the circulating movement of the nozzle tube  22 . According to a further example, it is provided to record an angle position of the first shaft  21  by means of an encoder and to pivot the nozzle tube  22  as a function of the recorded angle position by means of a motorized or hydraulically driven actuator. Such an actuator could execute a pivoting movement of the nozzle tube as a function of an angle position of the first shaft  21  via a lever assembly of the type shown in  FIGS.  4 A- 4 C . 
       FIG.  5    illustrates cleaning jets which are discharged during a circulation track of the nozzle tube  22  about the workpiece carrier  3  or the workpiece  5 , wherein the nozzle tube in this example pivots five times completely during one revolution. Accordingly, there are five hotspot areas HS 1 -HS 5 , i.e. five areas of a circulation track of the nozzle tube  22  in which a hotspot can occur when the rotational speeds ω21, ω31 of the first and second shaft  21 ,  31  are suitably adapted to one another, for example according to equations (3) and (6). 
     According to one example, it is provided to select target values for rotational speeds ω21, ω31 and to keep the rotational speeds constant at the respective target value for the duration of the rotation process based on the desired cleaning time, the permissible ranges for the rotational speeds ω21, ω31, and the number n of pivoting movements occurring per revolution of the nozzle tube. To this end, control of the two motors  6 ,  7  may be provided in that, for example, the rotational speeds of the two shafts  21 ,  31  are recorded by means of encoders, said rotational speeds are compared to the target values, and the motors  6 ,  7  are actuated as a function of the comparison results. Without control of the motors  6 ,  7 , the circulation speed of the nozzle tube, for example, could then always temporarily accelerate due to the gravitational force when the nozzle tube  22  moves from a highest point on the circulation track (above as with the example according to  FIG.  1 B ) to a lowest point on the circulation track (below as with the example according to  FIG.  1 B ) and then always temporarily decelerate when the nozzle tube  22  moves from the lowest point on the circulation track (above as with the example according to  FIG.  1 B ) to the highest point on the circulation track. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.