Patent Description:
The device comprises a frame, a transfer roller with a circumferential lateral wall, a nozzle preferably in the form of a slit nozzle with a muzzle end for dispensing lacquer, and a hardening unit. The nozzle and the hardening unit are each at least 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. The hardening unit is 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 present invention is any kind of UV-radiation. The hardening unit is arranged within an interior space defined by or formed within the transfer roller. The lateral wall of the transfer roller is transparent for UV-light. The hardening unit is 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 being transferred to the work surface.

A similar device for lacquer transfer is known from <CIT>.

From <CIT> a method for ink jet printing of a curable ink with a three-dimensional structure is known. Ink is applied by a discharge unit to a base unit by an inkjet printing method, whereafter the ink is flattened by rollers and cured by irradiation units using light shielding units.

With known devices for lacquer transfer it might occur that lacquer is unintentionally prehardened at an early stage at the transfer roller by scattered, indirect UV-light, so that parts of the lacquer adhere to the transfer roller instead of being transferred to the work surface.

Therefore, an object of the present invention is to provide a device by which lacquer transfer from the transfer roller to the work surface can be carried out more reliably.

This object is achieved by a device comprising the features of claim <NUM>. Specifically, the object is achieved in that the device comprises a light shield arranged between the hardening unit and the outside contact surface, such that at least a portion of the outside contact surface provided with lacquer, i.e. a portion of the contact surface upstream from a transfer area in which the lacquer is transferred to the work surface, is shielded from UV-light emitted from the hardening unit. In such a way, only the transfer area where hardening of the lacquer is intended is exposed to UV-light and an early stage prehardening of lacquer at the transfer roller upstream from the intended transfer area can be avoided, thereby allowing a more complete and reliable lacquer transfer.

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 slit nozzle and the hardening unit are each at least indirectly connected to the frame. For this purpose, the device may comprise further connecting means for connecting the slit nozzle to the frame and/or further connecting means for connecting the hardening unit to the frame. Thus, the slit nozzle and the hardening unit may be mounted to the frame. The slit nozzle may be releasably connected to the frame. Thus, the slit nozzle may be disconnected form the frame, in particular for a maintenance purpose. The slit nozzle may be connected to the frame, such that the slit nozzle can be releasably locked in a working position. If this lock is released, the slit nozzle may be pivoted via a hinge, which holds the slit nozzle at the frame. Thus, the slit 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 slit 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 slit nozzle. The lacquer can be hardened via UV-light. The lacquer supplied to the slit nozzle may be a liquid medium or a viscous medium.

According a first nozzle arrangement of the slit 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 slit 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 slit 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 slit nozzle is configured for dispensing lacquer into the depressions of the lateral wall of the transfer roller. The slit nozzle may also be configured for dispensing lacquer onto depression-free sections of the lateral wall of the transfer roller. Thus, the slit 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 slit nozzle is arranged according to the fisrt nozzle arrangement. A distance formed by the gap between the slit nozzle and the outside contact surface at the second deformation section may be predefined by an arrangement of the slit nozzle according to the second nozzle arrangement, such that lacquer dispensed by the slit nozzle continuously forms the lacquer film on the 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 light shield comprises a shield opening, preferably elongate and in parallel to the axis of rotation, for letting through UV-light emitted from the hardening unit. Preferably, the shield opening is arranged opposite, in particular above a transfer area in which the lacquer is transferred to the work surface. The shield opening defines the angle or area in which UV-light emitted from the hardening unit is directly let through to the lacquer on the outside contact surface of the transfer roller and on the work surface respectively.

According to a further preferred embodiment, the light shield has a shape of a cylinder shell segment preferably having a circular cross section interrupted by the shield opening. By such a shape the light shield circumferentially covers the entire angular range around the hardening unit, accept from the shield opening. The cylindrical shape is particularly advantageous as it fits to the shape of the transfer roller and can be arranged close to or adapted to the outer contact surface.

According to another preferred embodiment, the light shield is arranged proximate the lateral wall, preferably opposite an inner surface of the lateral wall. In such a way, the amount of scattered light reaching the lacquer at areas outside the transfer area can be widely reduced.

According to the invention, the transfer roller is formed as a tire having a circular, preferably torus-shaped pressure chamber between the lateral wall and an inner wall directed to the interior space. Similar as the lateral wall the inner wall is transparent for UV-light, so that UV-light emitted from the hardening unit inside the interior space can shine through the entire transfer roller to harden the lacquer on the outside contact surface. The pressure chamber is preferably inflated with pressurized air and at least the lateral wall is formed elastically to be able to adapt the outer contact surface in contact with the work surface depending on the air pressure in the pressure chamber, and thus to adapt the angular range of the transfer area along the work surface. The light shield is arranged inside the pressure chamber between the lateral wall and the inner wall. In such a way, the light shield can be arranged near and opposite the lateral wall.

In particular, it is preferred that the light shield is held in position inside the rotating transfer roller by magnetic force, preferably in a static angular position about the axis of rotation with the shield opening opposite the transfer area. The magnetic force allows to hold the light shield in a contactless manner, so that the light shield can be held in a static angular position from outside the transfer roller while the transfer roller, in the atmospherically sealed pressure chamber of which the light shield is arranged, rotates.

It is further preferred that a magnet, in particular an electromagnet or a permanent magnet, is mounted directly or indirectly to the frame, while a magnetic element is mounted to or part of the light shield in a position opposite the magnet, such that the magnetic force acts between the magnet and the magnetic element, preferably attracts the magnetic element to the magnet. In such a way, a simple magnetic coupling between the frame and the light shield is provided.

It is also preferred that the light shield is rotatably supported inside the transfer roller by a roller bearing. In such a way, the light shield can rotate relative to the transfer roller about the axis of rotation and at the same time is supported in a radial direction by the transfer roller.

In particular, it is preferred that the roller bearing comprises a plurality of rollers supporting the light shield against the inner wall. The rollers preferably have axes of rotation in parallel to the axis or rotation of the transfer roller. In such a way, the light shield is supported in radial direction by the inner wall.

Further features, advantages and application possibilities of the present invention may be derived from the following description of exemplary 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 present invention 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> schematically illustrates an aircraft <NUM>, which comprises a fuselage <NUM> and a wing <NUM>. The air resistance of the aircraft <NUM> can be reduced, if the upper wing surface <NUM> of the wing <NUM> comprises a profile structure. It has been found of advantage, if this profile structure is a microstructure.

<FIG> also schematically shows a robot <NUM>, which is seated on a rack <NUM>. The robot <NUM> comprises a movable robot arm <NUM>. A device <NUM> is mounted at an end of the robot arm <NUM>, such that the device <NUM> can be moved by the robot <NUM>.

The device <NUM> is configured for transferring a lacquer onto a work surface <NUM> of a workpiece <NUM>. According to the example shown in <FIG>, the workpiece <NUM> can be formed by the wing <NUM> of the aircraft <NUM>. Thus, the upper wing surface <NUM> can form the work surface <NUM>.

A first embodiment of the device <NUM> is schematically illustrated in <FIG> in a cross-sectional view. The device <NUM> comprises a frame <NUM>, a transfer roller <NUM> with a circumferential lateral wall <NUM>, a drive unit <NUM>, a slit nozzle <NUM> with a muzzle end <NUM> for dispensing lacquer, and a deformation unit <NUM>. The transfer roller <NUM> may also be referred to as a transfer tire. The device <NUM> can be attached via the frame <NUM> to the robot arm <NUM>. However, instead of a robot <NUM> any other handling device may also be used, which is configured to move the device <NUM> in space. The frame <NUM> may be adapted to be releasably connected to a handling device, such as the robot <NUM>.

The transfer roller <NUM> is mounted rotatably, in particular by means of at least one bearing, about an axis of rotation <NUM> at the frame <NUM>. An outside contact surface <NUM> of the lateral wall <NUM> comprises several depressions <NUM>. The depressions <NUM> may be evenly or stochastically distributed about the circumference of the lateral wall <NUM>. The <FIG> show a part of the transfer roller <NUM> in a cross-section view and a top view, respectively.

As schematically indicated in <FIG>, the depressions <NUM> can be formed by recesses arranged at the outside surface <NUM> of the lateral wall <NUM> of the transfer roller <NUM>. The depressions <NUM> can have a predefined size and/or structure. A mean structure size of the depressions <NUM> can be in the range of <NUM>,<NUM> micrometer to <NUM> micrometer. In other words, each of the depressions <NUM> may have a microstructure.

<FIG> exemplarily shows the depressions <NUM> of a part of the lateral wall <NUM> of the transfer roller <NUM> in a top view. Each of the depressions <NUM> may comprise an elongated extension in a circumferential direction U of the lateral wall <NUM> of the transfer roller <NUM>.

Each of the depressions <NUM> is configured to receive lacquer and to transfer this received lacquer to a work surface <NUM> of a work piece <NUM>, such as the upper wing surface <NUM> of a wing <NUM>. Therefore, the several depressions <NUM> at the outside contact surface <NUM> of the lateral wall <NUM> may be arranged and/or formed according to a predefined structure, in particular a microstructure. The lateral wall <NUM> is preferably made of silicone, such that a damage of the wing surface <NUM> can be prevented.

If the depressions <NUM> are filled with a lacquer and if the outside contact surface <NUM> comes into contact with the work surface <NUM>, in particular the upper wing surface <NUM>, the lacquer previously received in the depressions <NUM> is transferred to the work surface <NUM>, in particular the upper outside surface <NUM> of the aircraft <NUM>. This transferred lacquer has a structure, in particular microstructure, corresponding to a structure defined by depressions <NUM>. Thus, the outside contact surface <NUM> with its depressions <NUM> is configured for embossing a lacquer-structure, in particular a lacquer-microstructure, on the work surface <NUM>, in particular the upper wing surface <NUM>.

As schematically illustrated in <FIG>, the slit nozzle <NUM> is directly or indirectly connected to the frame <NUM>. Thus, the slit nozzle <NUM> may be mounted to the frame <NUM>. Furthermore, the deformation unit <NUM> is directly or indirectly connected to the frame <NUM>. For instance, the deformation unit <NUM> may be mounted on the frame <NUM>. According to an example not illustrated in <FIG>, the slit nozzle <NUM> and the deformation unit <NUM> may be formed by an integrated unit. But the slit nozzle <NUM> may also be directly connected to the deformation unit <NUM>, or vice versa. Thus, the slit nozzle <NUM> and the deformation unit <NUM> may be mounted in series to the frame <NUM>.

The device <NUM> also comprises the drive unit <NUM>. The drive unit <NUM> is configured to drive the transfer roller <NUM> in a rotation direction K about the axis of rotation <NUM>.

The lateral wall <NUM> of the transfer roller <NUM> is elastically deformable in a radial direction R of the transfer roller <NUM>. The lateral wall <NUM> of the transfer roller <NUM> can be made of an elastomer plastic, a silicone or any other elastically deformable plastic material. Preferably, the lateral wall <NUM> of the transfer roller <NUM> is made of a synthetic, elastically deformable silicone. As a result, the lateral wall <NUM> can be at least section-wise deformed in positive or negative radial direction R. The deformation unit <NUM> is configured to deform the lateral wall <NUM> in the radial direction R of the transfer roller <NUM> upstream from the slit nozzle <NUM> to provide a stable distance of the lateral wall <NUM> to the muzzle end <NUM> of the slit nozzle <NUM> for a defined application of lacquer to the outside contact surface <NUM> of the lateral wall <NUM>. 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 <NUM> further comprises a hardening unit <NUM>. The hardening unit <NUM> is configured for hardening the lacquer in a contactless way. The hardening unit <NUM> is formed by an UV-light unit. The hardening unit <NUM> is directly or indirectly connected to the frame <NUM>. Moreover, the hardening unit <NUM> is arranged within the interior space <NUM> formed by the transfer roller <NUM>. The lateral wall <NUM> of the transfer roller <NUM> is configured to transmit UV-light-waves. Thus, the lateral wall <NUM> is transparent for UV-light. The hardening unit <NUM> is arranged, such that UV-light is emitted towards the work surface <NUM> upon which the lateral wall <NUM> of the transfer roller <NUM> rolls. The lacquer is hardenable via UV-light. Therefore, the device is configured to control the drive unit <NUM> and/or the hardening unit <NUM> such that lacquer transferred to the work surface <NUM> is immediately hardened via UV-light emitted by the hardening unit <NUM>.

As shown in <FIG>, the device <NUM> comprises a light shield <NUM> arranged between the hardening unit <NUM> and the outside contact surface <NUM>, such that at least a portion of the outside contact surface <NUM> provided with lacquer, specifically a portion of the contact surface upstream from a transfer area <NUM> in which the lacquer is transferred to the work surface <NUM>, is shielded from UV-light emitted from the hardening unit <NUM>.

The light shield <NUM> comprises a shield opening <NUM> in parallel to the axis of rotation <NUM> for letting through UV-light emitted from the hardening unit <NUM>. The shield opening <NUM> is arranged opposite the transfer area <NUM> in which the lacquer is transferred to the work surface <NUM>. The light shield <NUM> has a shape of a cylinder shell segment with a circular cross section interrupted by the shield opening <NUM>.

The transfer roller <NUM> is formed as a tire having a circular pressure chamber <NUM> inflated with pressurized air between the lateral wall <NUM> and an inner wall <NUM> directed to the interior space <NUM>. Similar as the lateral wall <NUM> the inner wall <NUM> is transparent for UV-light. The light shield <NUM> is arranged inside the pressure chamber <NUM> between the lateral wall <NUM> and the inner wall <NUM> to be arranged proximate the lateral wall <NUM>.

The light shield <NUM> is held in position inside the rotating transfer roller <NUM> with the shield opening <NUM> opposite the transfer area <NUM> by magnetic force, wherein a magnet <NUM> is mounted to the frame <NUM> and a corresponding magnetic element <NUM> is mounted to the light shield <NUM> in a position opposite the magnet <NUM>, such that the magnetic force acts between the magnet <NUM> and the magnetic element <NUM> and attracts the magnetic element <NUM> to the magnet <NUM>.

The light shield <NUM> is rotatably supported inside the transfer roller <NUM> by a roller bearing <NUM> comprising a plurality of rollers <NUM> supporting the light shield <NUM> against the inner wall <NUM>.

Claim 1:
A device (<NUM>) for lacquer transfer, comprising
a frame (<NUM>),
a transfer roller (<NUM>) with a circumferential lateral wall (<NUM>),
a nozzle (<NUM>) for dispensing lacquer, and
a hardening unit (<NUM>),
wherein the nozzle (<NUM>) and the hardening unit (<NUM>) are each at least indirectly connected to the frame (<NUM>),
wherein an outside contact surface (<NUM>) of the lateral wall (<NUM>) comprises several depressions (<NUM>),
wherein the transfer roller (<NUM>) is mounted rotatably about an axis of rotation (<NUM>) at the frame (<NUM>),
wherein the nozzle (<NUM>) is arranged contactless to or in direct contact with the outside contact surface (<NUM>) of the lateral wall (<NUM>) for dispensing lacquer into respective depressions (<NUM>) in the lateral wall (<NUM>) while the transfer roller is rotated about the axis of rotation (<NUM>),
wherein the transfer roller (<NUM>) is configured to roll with the outside contact surface (<NUM>) on a work surface (<NUM>) of a work piece (<NUM>) for transferring the lacquer from the depressions (<NUM>) to the work surface (<NUM>) of the work piece (<NUM>),
wherein the hardening unit (<NUM>) is formed as a UV-light unit configured for hardening the lacquer in a contactless way by emitting UV-light,
wherein the hardening unit (<NUM>) is arranged within an interior space (<NUM>) defined by the transfer roller (<NUM>),
wherein the lateral wall (<NUM>) of the transfer roller (<NUM>) is transparent for UV-light, and
wherein the hardening unit (<NUM>) is arranged such that UV-light is emitted towards the work surface (<NUM>) upon which the lateral wall (<NUM>) of the transfer roller (<NUM>) rolls, to harden the lacquer after it being transferred to the work surface (<NUM>),
characterized in that
the device (<NUM>) comprises a light shield (<NUM>) arranged between the hardening unit (<NUM>) and the outside contact surface (<NUM>), such that at least a portion of the outside contact surface (<NUM>) provided with lacquer is shielded from UV-light emitted from the hardening unit (<NUM>),
wherein the transfer roller (<NUM>) is formed as a tire having a circular pressure chamber (<NUM>) between the lateral wall (<NUM>) and an inner wall (<NUM>) directed to the interior space (<NUM>), and
wherein the light shield (<NUM>) is arranged inside the pressure chamber (<NUM>) between the lateral wall (<NUM>) and the inner wall (<NUM>).