Patent Publication Number: US-2022219195-A1

Title: Device for lacquer transfer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German patent application DE 10 2021 100 409.8 filed Jan. 12, 2021, the entire disclosure of which is incorporated by reference herein. 
     TECHNICAL FIELD 
     The disclosure herein relates to a device for lacquer transfer to a work surface, in particular to an aerodynamic surface of an aircraft, such as an outer surface of a wing. Further aspects of the disclosure herein relate to a method for producing an aircraft component, as well as to an aircraft or aircraft component producible by such a method. 
     BACKGROUND 
     The device comprises a frame, a transfer roller with a circumferential lateral wall, and a nozzle, preferably in the form of a slit nozzle with a muzzle end, for dispensing lacquer. The nozzle is directly or indirectly connected to the frame. An outside contact surface of the lateral wall comprises several depressions. The transfer roller is mounted rotatably about an axis of rotation at the frame. The nozzle is arranged contactless to or in direct contact with the outside contact surface of the lateral wall for dispensing lacquer into respective depressions in the lateral wall while the transfer roller is rotated about the axis of rotation. The transfer roller is configured to roll with the outside contact surface on a work surface of a work piece for transferring the lacquer from the depressions to the work surface of the work piece. 
     Further, the depressions are formed and distributed over the outside contact surface according to a predefined pattern, wherein the depressions are preferably in the form of a microstructure. The pattern has a main orientation direction that is intended to be aligned with a longitudinal axis and/or flight direction of an aircraft or aircraft component to which the lacquer is transferred, in order to benefit from the aerodynamic advantages of the depressions. 
     A similar device for lacquer transfer is known from WO 2015/155 128 A1. 
     The known devices for lacquer transfer have patterns of depressions in the outside contact surface that have a main orientation direction extending in the direction of movement of the transfer roller over the work surface during lacquer transfer, i.e. in the circumferential direction of the transfer roller and perpendicular to the axis of rotation of the transfer roller. This means, in order to transfer lacquer to an outer surface of an aircraft with the main orientation direction of the pattern in parallel to the longitudinal axis of the aircraft, as required to benefit from the aerodynamic advantages of the depressions, the transfer roller must be rolled over the work surface only in parallel to the longitudinal axis of the aircraft for all kinds of aircraft components. However, some aircraft components, such as the wings, have an essentially greater extension in a direction transverse to the longitudinal axis than in parallel to the longitudinal axis. Lacquer transfer in case of such aircraft components thus cannot be carried out in the direction of the greatest extension of the aircraft component, but rather needs to be carried out in a direction transverse to the greatest extension of the aircraft component. However, deviating considerably from the direction of the greatest extension of the aircraft component decreases efficiency of the lacquer transfer process, since usually a higher number of roller tracks are required to cover the entire component with lacquer, which in turn requires a higher number of repositioning cycles where the device is repositioned to the beginning of a new roller track after a previous roller track is completed. A higher number of roller tracks and repositioning cycles increases time and effort required for the entire lacquer transfer process. 
     SUMMARY 
     Therefore, an object of the disclosure herein is to provide a device by which efficiency of lacquer transfer can be increased. 
     This object is achieved by a device disclosed herein. Specifically, the object is achieved in that the pattern is arranged such that the main orientation direction extends other than perpendicular to the axis of rotation of the transfer roller, i.e. other than in a circumferential direction of the transfer roller, and thus, other than parallel to the direction of movement of the transfer roller over the work surface during lacquer transfer. In such a way, the direction in which the transfer roller is rolled and lacquer is transferred on the work surface of an aircraft component, can be aligned with the direction of the greatest extension of the aircraft component, while the main orientation direction of the pattern of depressions can still be aligned with the longitudinal axis of the aircraft or aircraft component to which lacquer is transferred and with the normal flight direction of the aircraft, respectively. 
     The device preferably further comprises a hardening unit that might be connected directly or indirectly to the frame and that might be formed as a UV-light unit configured for hardening the lacquer in a contactless way by emitting UV-light. UV-light within the meaning of the disclosure herein is any kind of UV-radiation. The hardening unit might be arranged within an interior space defined by or formed within the transfer roller. The lateral wall of the transfer roller might be transparent for UV-light. The hardening unit might be arranged such that UV-light is emitted towards the work surface upon which the lateral wall of the transfer roller rolls, to harden the lacquer preferably immediately after it is transferred to the work surface. 
     Preferably, the device or at least its frame is configured to be releasably connected to a handling device, such as a robot with a robot arm. The frame may be configured to be releasably connected to the robot arm. Thus, the device may be a mobile device, in particular a mobile mechanical device. 
     The frame may form the bases of the device, since the nozzle and the hardening unit are each at least indirectly connected to the frame. For this purpose, the device may comprise further connecting structure for connecting the nozzle to the frame and/or further connecting structure for connecting the hardening unit to the frame. Thus, the nozzle and the hardening unit may be mounted to the frame. The nozzle may be releasably connected to the frame. Thus, the nozzle may be disconnected form the frame, in particular for a maintenance purpose. The nozzle may be connected to the frame, such that the nozzle can be releasably locked in a working position. If this lock is released, the nozzle may be pivoted via a hinge, which holds the nozzle at the frame. Thus, the nozzle may then be subject to a maintenance procedure. 
     The transfer roller is mounted rotatably to the frame. The transfer roller can therefore rotate about the axis of rotation. For this purpose, the device may comprise a drive unit, which is configured to drive the transfer roller in a rotation direction of the transfer roller about the axis of rotation. The drive unit may also be at least indirectly connected or mounted to the frame. During use, the drive unit drives the transfer roller, such that the transfer roller rotates about the axis of rotation and roles with the contact surface on a work surface. Furthermore, the device is moved translational in parallel to the work surface, preferably by a robot arm or another handling device, while the transfer roller rotates, such that the transfer roller rolls on the work surface for transferring lacquer. 
     The nozzle may be connected via a pipe or a tube to a lacquer supply unit, which may be configured to supply the lacquer via the tube or the pipe to the nozzle. The lacquer can be hardened via UV-light. The lacquer supplied to the nozzle may be a liquid medium or a viscous medium. 
     According a first nozzle arrangement of the nozzle, the muzzle end of the slit nozzle may be arranged contactless to the outside contact surface of the lateral wall for dispensing lacquer into respective depressions. 
     According to an alternative second nozzle arrangement of the nozzle, the muzzle end of the slit nozzle is arranged in direct contact with the outside contact surface of the lateral wall for dispensing lacquer into respective depressions. 
     If reference is subsequently made to the nozzle without explicitly specifying the first or second nozzle arrangement, the corresponding explanations may, in principle, apply as preferred embodiments to each of the two arrangements. Therefore, it may be possible to apply the respective explanations to one of the first and second nozzle arrangement or to both nozzle arrangements. 
     The nozzle is configured for dispensing lacquer into the depressions of the lateral wall of the transfer roller. The nozzle may also be configured for dispensing lacquer onto depression-free sections of the lateral wall of the transfer roller. Thus, the nozzle may be configured for dispensing a lacquer film onto the lateral wall of the transfer roller, wherein the lacquer of the lacquer film fills the depressions and the lacquer film extends in axial direction and partly in circumferential direction of the transfer roller. The lacquer film may therefore theoretically divide into a depression part, which fills the depressions, and a remaining part, which is also referred to as bulk or a bulk part. Therefore, the transfer roller may be configured to roll with the contact surface of the transfer roller on a work surface of a work piece for transferring the lacquer from the contact surface to the work surface of the work piece, such that the lacquer film is transferred to the work surface. This encompassed the transfer of the lacquer from the depressions, but also the transfer of the bulk part. If the transfer of the lacquer from the depressions to the work surface, in particular to a surface of a wing, is described in the following, this shall preferable not exclude the possible transfer of the bulk part to the respective surface and/or the possible transfer of the lacquer from the depressions via the lacquer film. 
     Resulting from the direct contact between the muzzle end of the slit nozzle and the outside surface of the lateral wall of the transfer roller, preferably if the slit nozzle is in the second nozzle arrangement, a desired fill level of the depressions may be ensured and/or a desired mean thickness of the lacquer film may be ensured. However, a resulting contact force and/or a resulting contact friction should not change as much as possible during a rotation of the transfer roller in order to prevent a slip-stick-effect. 
     But a desired fill level of the depression may also be ensured and/or a desired mean thickness of the lacquer film on the outside surface of the lateral wall may be ensured, if the muzzle end of the slit nozzle is arranged contactless to the outside contact surface of the lateral wall, in particular, if the nozzle is arranged according to the first nozzle arrangement. A distance formed by the gap between the nozzle and the outside contact surface at the second deformation section may be predefined by an arrangement of the nozzle according to the second nozzle arrangement, such that lacquer dispensed by the nozzle continuously forms the lacquer film on the outside surface of the lateral wall, preferably with a predefined thickness. The dispensed lacquer therefore fills the aforementioned gap with the lacquer. As an effect, lacquer also fills the depressions of the outside contact surface at the second deformation section of the lateral wall. As a further effect, a bulk part may also be applied to the outside contact surface at the second deformation section of the lateral wall. 
     According to a preferred embodiment, the pattern is formed such that along the main orientation direction the depressions are arranged in a repetitive, preferably periodic, manner and/or have a repetitively, preferably periodically, varying form. Such a repetitively varying arrangement or form of the depressions, which might be e.g., sheds or grooves with repetitively curving side walls, cause advantageous flow conditions in the main orientation direction, specifically minimum drag and maximum efficient flow. 
     According to an alternative embodiment, the pattern is formed such that along the main orientation direction the depressions have a constant form, i.e. have a constant cross section along the main orientation direction. This means, the depressions are formed as tracks or grooves with straight side walls extending in the main orientation direction. Such constantly formed depressions cause advantageous flow conditions in the main orientation direction, specifically minimum drag and maximum efficient flow. 
     According to another preferred embodiment, wherein the pattern is formed such that the depressions are formed and arranged as parallel grooves extending in the main orientation direction. Such groove-shaped depressions cause advantageous flow conditions in the main orientation direction, specifically minimum drag and maximum efficient flow. 
     According to a further embodiment, the pattern is formed such that along the main orientation direction the depressions are formed and arranged in a streamlined manner, in particular streamlined with respect to a fluid streaming in the main orientation direction. Such streamlined depressions cause advantageous flow conditions in the main orientation direction, specifically minimum drag and maximum efficient flow. 
     According to a further embodiment, the pattern is formed such that along the main orientation direction the depressions are formed and arranged to cause a minimum drag and/or maximum efficient flow, compared to other directions, when the lacquer has been transferred to an aircraft component and the depressions are passed by ambient flow. In such a way, the depressions have an advantageous effect on the associated aircraft component. 
     According to a further embodiment, the pattern is arranged such that the main orientation direction extends in parallel to the axis of rotation of the transfer roller. In such a way, lacquer might be transferred to aircraft or aircraft components with the transfer roller rolling in a direction perpendicular to the longitudinal axis of the aircraft or aircraft component while the main orientation direction of the pattern is still aligned with the longitudinal axis. This is particularly advantageous for lacquer transfer to aircraft components having a direction of the greatest extension perpendicular to the longitudinal direction, which might be the case e.g., for some wing or tail unit parts, since rolling the transfer roller in the direction of the greatest extension of the aircraft component is usually most effective due to a minimum number of roller tracks required to cover the entire aircraft component and thus a minimum repositioning effort for the device. 
     According to an alternative embodiment, the pattern is arranged such that the main orientation direction extends angled, i.e. skewed, preferably angled by an angle of between 1° and 89°, relative to both the axis of rotation of the transfer roller and the circumferential direction of the transfer roller. In such a way, lacquer might be transferred to aircraft or aircraft components with the transfer roller rolling in a direction angled to the longitudinal axis of the aircraft or aircraft component while the main orientation direction of the pattern is still aligned with the longitudinal axis. This is particularly advantageous for lacquer transfer to aircraft components having a direction of the greatest extension angled to the longitudinal direction, which might be the case e.g. for some wing or tail unit parts, since rolling the transfer roller in the direction of the greatest extension of the aircraft component is usually most effective due to a minimum number of roller tracks required to cover the entire aircraft component and thus a minimum repositioning effort for the device. 
     A further aspect of the disclosure herein relates to a method for producing an aircraft component, in particular to a method for lacquer transfer to an aircraft component, comprising the following steps: An aircraft component, which may also be an entire aircraft, is provided having a longitudinal axis, preferably in parallel to the flight direction of the associated aircraft during normal flight conditions, and having a work surface at its outer surface, to which lacquer is to be transferred. The outer surface of the aircraft component relates to its aerodynamic surface that is in contact with an ambient flow. Further, a device for lacquer transfer according to any of the embodiments described above is provided. Then, lacquer is transferred to the work surface by moving the device for lacquer transfer such that the transfer roller rolls over the work surface in a direction transverse to the longitudinal axis, preferably perpendicular or skewed with respect to the longitudinal axis, to have the main orientation direction of the pattern of depressions in parallel to the longitudinal axis. The features and effects of the device for lacquer transfer described above apply vis-à-vis also to the method for producing the aircraft component. 
     According to a preferred embodiment, lacquer is transferred to the work surface by rolling the transfer roller in a direction of the greatest extension of the aircraft component. This relates to a very efficient lacquer transfer process, since a minimum number of roller tracks is required to cover the entire aircraft component, leading to a minimum repositioning effort for the device. 
     Yet a further aspect of the disclosure herein relates to an aircraft or aircraft component having an outer surface coated with structured, in particular microstructured, lacquer, producible or produced with the method according to any of the embodiments described above. The features and effects of the device for lacquer transfer described above as well as the features and effects of the method for producing an aircraft component as described above, apply vis-à-vis also to the aircraft and aircraft component, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, advantages and application possibilities of the disclosure herein may be derived from the following description of example embodiments and/or the figures. Thereby, all described and/or visually depicted features for themselves and/or in any combination may form an advantageous subject matter and/or features of the disclosure herein independent of their combination in the individual claims or their dependencies. Furthermore, in the figures, same reference signs may indicate same or similar objects. 
         FIG. 1  schematically illustrates a part of an aircraft wherein a device arranged for transferring lacquer on an upper wing surface. 
         FIG. 2  schematically illustrates an embodiment of the device in a cross-sectional view with a perspective detailed view of the muzzle end of the slit nozzle. 
         FIG. 3  schematically illustrates a part of the lateral wall of the transfer roller in a cross-sectional view. 
         FIG. 4  schematically illustrates a further embodiment of the lateral wall of the transfer roller in a top view. 
         FIG. 5  schematically illustrates a transfer roller as known in the art having depressions in the outside contact surface formed as circumferential grooves. 
         FIG. 6  schematically illustrates a transfer roller according to the disclosure herein having depressions in the outside contact surface formed as axial grooves. 
         FIG. 7  schematically illustrates an aircraft component to which lacquer has been transferred by the known roller as shown in  FIG. 5 . 
         FIG. 8  schematically illustrates an aircraft component to which lacquer has been transferred by the roller according to the disclosure herein as shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an aircraft  42 , which comprises a fuselage  44  and a wing  46 . The air resistance of the aircraft  42  can be reduced, if the upper wing surface  48  of the wing  46  comprises a profile structure. It has been found of advantage if this profile structure is a microstructure. 
       FIG. 1  also schematically shows a robot  50 , which is seated on a rack  54 . The robot  50  comprises a movable robot arm  52 . A device  2  is mounted at an end of the robot arm  52 , such that the device  2  can be moved by the robot  50 . 
     The device  2  is configured for transferring a lacquer onto a work surface  32  of a workpiece  34 . According to the example shown in  FIG. 1 , the workpiece  34  can be formed by the wing  46  of the aircraft  42 . Thus, the upper wing surface  48  can form the work surface  32 . 
     A first embodiment of the device  2  is schematically illustrated in  FIG. 2  in a cross-sectional view. The device  2  comprises a frame  4 , a transfer roller  6  with a circumferential lateral wall  8 , a drive unit  10 , a slit nozzle  12  with a muzzle end  14  for dispensing lacquer, and a deformation unit  16 . The transfer roller  6  may also be referred to as a transfer tire. The device  2  can be attached via the frame  4  to the robot arm  52 . However, instead of a robot  50  any other handling device may also be used, which is configured to move the device  2  in space. The frame  4  may be adapted to be releasably connected to a handling device, such as the robot  50 . 
     The transfer roller  6  is mounted rotatably, in particular by at least one bearing, about an axis of rotation  22  at the frame  4 . An outside contact surface  18  of the lateral wall  8  comprises several depressions  20  (better evident in  FIG. 3 ). The depressions  20  may be evenly or stochastically distributed about the circumference of the lateral wall  8 . The  FIGS. 3 and 4  show a part of the transfer roller  6  in a cross-section view and a top view, respectively. 
     As schematically indicated in  FIG. 3 , the depressions  20  can be formed by recesses arranged at the outside surface  18  of the lateral wall  8  of the transfer roller  6 . The depressions  20  can have a predefined size and/or structure. A mean structure size of the depressions  20  can be in the range of 0.1 micrometer to 100 micrometer. In other words, each of the depressions  20  may have a microstructure. 
       FIG. 4  shows as an example the depressions  20  of a part of the lateral wall  8  of the transfer roller  6  in a top view. Each of the depressions  20  may comprise an elongated extension, in the present embodiment extending perpendicular to a circumferential direction U of the lateral wall  8  of the transfer roller  6 . 
     Each of the depressions  20  is configured to receive lacquer and to transfer this received lacquer to a work surface  32  of a work piece  34 , such as the upper wing surface  48  of a wing  26 . Therefore, the several depressions  20  at the outside contact surface  18  of the lateral wall  8  may be arranged and/or formed according to a predefined structure, in particular a microstructure. The lateral wall  8  is preferably made of silicone, such that a damage of the wing surface  48  can be prevented. 
     If the depressions  20  are filled with a lacquer and if the outside contact surface  18  comes into contact with the work surface  32 , in particular the upper wing surface  48 , the lacquer previously received in the depressions  20  is transferred to the work surface  32 , in particular the upper outside surface  48  of the aircraft  42 . This transferred lacquer has a structure, in particular microstructure, corresponding to a structure defined by depressions  20 . Thus, the outside contact surface  18  with its depressions  20  is configured for embossing a lacquer-structure, in particular a lacquer-microstructure, on the work surface  32 , in particular the upper wing surface  48 . 
     As schematically illustrated in  FIG. 2 , the slit nozzle  12  is directly or indirectly connected to the frame  4 . Thus, the slit nozzle  12  may be mounted to the frame  4 . Furthermore, the deformation unit  16  is directly or indirectly connected to the frame  4 . For instance, the deformation unit  16  may be mounted on the frame  4 . According to an example not illustrated in  FIG. 2 , the slit nozzle  12  and the deformation unit  16  may be formed by an integrated unit. But the slit nozzle  12  may also be directly connected to the deformation unit  16 , or vice versa. Thus, the slit nozzle  12  and the deformation unit  16  may be mounted in series to the frame  4 . 
     The device  2  also comprises the drive unit  10 . The drive unit  10  is configured to drive the transfer roller  6  in a rotation direction K about the axis of rotation  22 . 
     The lateral wall  8  of the transfer roller  6  is elastically deformable in a radial direction R of the transfer roller  6 . The lateral wall  8  of the transfer roller  6  can be made of an elastomer plastic, a silicone or any other elastically deformable plastic material. Preferably, the lateral wall  8  of the transfer roller  6  is made of a synthetic, elastically deformable silicone. As a result, the lateral wall  8  can be at least section-wise deformed in positive or negative radial direction R. The deformation unit  16  is configured to deform the lateral wall  8  in the radial direction R of the transfer roller  6  upstream from the slit nozzle  12  to provide a stable distance of the lateral wall  8  to the muzzle end  14  of the slit nozzle  12  for a defined application of lacquer to the outside contact surface  18  of the lateral wall  8 . If references made to the radial direction R, this may refer to the positive radial direction R or an opposite negative radial direction. 
     The device  2  further comprises a hardening unit  60 . The hardening unit  60  is configured for hardening the lacquer in a contactless way. The hardening unit  60  is formed by an UV-light unit. The hardening unit  60  is directly or indirectly connected to the frame  4 . Moreover, the hardening unit  60  is arranged within the interior space  36  formed by the transfer roller  6 . The lateral wall  8  of the transfer roller  6  is configured to transmit UV-light-waves. Thus, the lateral wall  8  is transparent for UV-light. The hardening unit  60  is arranged, such that UV-light is emitted towards the work surface  32  upon which the lateral wall  8  of the transfer roller  6  rolls. The lacquer is hardenable via UV-light. Therefore, the device is configured to control the drive unit  10  and/or the hardening unit  60  such that lacquer transferred to the work surface  32  is immediately hardened via UV-light emitted by the hardening unit  60 . 
     As shown in  FIGS. 3 and 4 , the depressions  20  are formed and distributed over the outside contact surface  18  according to a predefined pattern. The pattern has a main orientation direction  62  that is intended to be aligned with a longitudinal axis  64  and flight direction of the aircraft  42  or aircraft component  66  to which the lacquer is transferred, in order to benefit from the aerodynamic advantages of the depressions  20 . In the embodiment shown in  FIGS. 3 and 4 , the pattern is formed such that the depressions  20  are formed and arranged as parallel grooves  68  extending in the main orientation direction  62  and having cross sections that are constant along the main orientation direction  62 . In such a way, the pattern is formed such that along the main orientation direction  62  the depressions  20  are formed and arranged in a streamlined manner with respect to a fluid streaming in the main orientation direction  62 , and are formed and arranged to cause a minimum drag and a maximum efficient flow, compared to other directions, when the lacquer has been transferred to an aircraft component  66  and the depressions are passed by ambient flow. 
       FIG. 5  shows a transfer roller  6 ′ known in the art and  FIG. 6  shows a transfer roller  6  according to the disclosure herein. While the known transfer roller  6 ′ shown in  FIG. 5  has a pattern of depressions  20 ′ formed by grooves  68 ′ with a main orientation direction  62 ′ in parallel to the circumferential direction U′, the transfer roller  6  according to the disclosure herein, as shown in  FIG. 6 , has a pattern of groove-shaped depressions  20  arranged such that the main orientation direction  62  extends perpendicular to the circumferential direction U and, thus, in parallel to the axis of rotation  22  of the transfer roller  6 . 
     In such a way, lacquer might be transferred to aircraft  42  or aircraft component  66  with the transfer roller  6  rolling in a direction perpendicular to the longitudinal axis  64  of the aircraft  42  or aircraft component  66  while the main orientation direction  62  of the pattern is still aligned with the longitudinal axis  64 . This is particularly advantageous for lacquer transfer to aircraft components  66  having a direction of the greatest extension  70  perpendicular to the longitudinal direction  64 , as shown for example in  FIG. 8 , since rolling the transfer roller  6  in the direction of the greatest extension  70  of the aircraft component  66  is usually most effective due to a minimum number of roller tracks  72  required to cover the entire aircraft component  66  and thus a minimum repositioning effort for the device  2 . 
     This is illustrated in  FIGS. 7 and 8 , where in  FIG. 7  an aircraft component  66  is shown to which lacquer has been transferred by the transfer roller  6 ′ shown in  FIG. 5 , and where in  FIG. 8  an aircraft component  66  with the same dimensions as the one from  FIG. 7  is shown, to which lacquer has been transferred by the transfer roller  6  shown in  FIG. 6 . While in  FIG. 7  five roller tracks  72  are required to cover the entire aircraft component  66  with lacquer, in  FIG. 8  only one roller track  72  is required to cover the entire aircraft component  66  with lacquer. This greatly reduces repositioning effort and increases efficiency of the process. 
     The aircraft component  66  shown in  FIG. 8  might be produced by the device  2  for lacquer transfer as described above having the transfer roller  6  shown in  FIG. 6 , by the following steps: The aircraft component  66  is provided having the longitudinal axis  64 , which is intended to be in parallel to the flight direction of the associated aircraft  42 , and having a work surface  32  at its outer surface, to which lacquer is to be transferred. The device  2  for lacquer transfer as described above is provided and lacquer is transferred to the work surface  32  by moving the device  2  such that the transfer roller  6  rolls over the work surface  32  in a direction perpendicular to the longitudinal axis  64  to have the main orientation direction  62  of the pattern of depressions  20  in parallel to the longitudinal axis  64 . At the same time, the transfer roller  6  is rolled in the direction of the greatest extension  70  of the aircraft component  66 , which provides that only one roller track  72  is required to cover the aircraft component  66  with lacquer. 
     By the device  2  for lacquer transferred according to the disclosure herein, as described above, the direction in which the transfer roller  6  is rolled and lacquer is transferred on the work surface  32  of an aircraft component  66 , can be aligned with the direction of the greatest extension  70  of the aircraft component  66 , while the main orientation direction  62  of the pattern of depressions  20  can still be aligned with the longitudinal axis  64  of the aircraft  42  or aircraft component  66  to which lacquer is transferred and with the normal flight direction of the aircraft  42 , respectively. 
     It is additionally pointed out that “comprising” does not rule out other elements, and “a” or “an” does not rule out a multiplicity. It is also pointed out that features that have been described with reference to one of the above example embodiments may also be disclosed as in combination with other features of other example embodiments described above. Reference signs in the claims are not to be regarded as restrictive. 
     While at least one example embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.