Paint booth and methods for operating a paint booth

Abstract

Paint booth with a working area (AB), an image acquisition device (14) whose detection area (EB) is directed towards the working area (AB) through a detection interface (16), and an annular nozzle (20) arranged inside the paint booth (1) in front of the detection interface (16), wherein the nozzle (20) radially surrounds the detection area (EB) of the image acquisition device (16) and has a nozzle outlet gap (26) inclined in the direction of the central longitudinal axis (L) of the nozzle (20), wherein the geometry of the nozzle outlet gap is configured to generate a conical and tapered fluid flow directed away from the detection interface towards the working area.

Description

The invention relates to a paint booth with image capture device and a method for operating the paint booth. In the topcoat application, clear coat is applied to a vehicle body. This is done, for example, using an airless sprayer. This process creates overspray. Some of this is carried downwards by the downward air currents in the paint booth. Nevertheless, deposits still form on the booth walls. Therefore, these are lined with foil. Cameras are necessary for measuring the body to allow robots to open the doors and hatches. These cameras are typically mounted outside the paint booth and separated from the interior by a glass panel. If the glass panel becomes dirty from the inside, it disrupts the camera images and the measurement process. Regular cleaning is necessary to prevent this disruption. This is not only time-consuming and expensive, but also poses a safety risk, as the cameras are often mounted overhead and require a ladder for cleaning. From publication JP 2016 - 32 798 A, a paint booth is known with a camera directed through an antifouling panel onto a work area. A first airflow device generates a downward airflow in the paint booth. To prevent paint deposits on the antifouling panel, the panel is inclined relative to the horizontal, causing the downward airflow to flow along the panel. Additionally, a second airflow device can be provided, which generates a local airflow in front of the camera lens, directed away from the camera lens. Furthermore, a device for applying coating powder is known from German patent application DE 77 13 282 U, and a device for extinguishing burning media sprayed from a spray device is known from German patent application DE 43 04 043 A1. The publication "Grindaix nozzles as 3D printing; https: / / grindaix.de / coolant-product / kuehlmittelduesen-3d-druck / " shows a nozzle manufactured using 3D printing. Against this background, the object of the invention is to show a way in which the cleaning effort in a paint booth can be reduced. The problem is solved by a paint booth according to claim 1 and a method according to claim 10. Further advantageous embodiments are described in the dependent claims and the following description. A paint booth is specified with a work area and an image capture device, the capture area of ​​which is directed towards the work area through a detection interface. According to the invention, an annular nozzle is arranged inside the paint booth in front of the detection interface, wherein the nozzle radially surrounds the detection area of ​​the camera device and has a nozzle exit gap inclined in the direction of the central longitudinal axis of the nozzle. In the arrangement according to the invention, the image acquisition device thus "looks" through the annular nozzle onto the working area of ​​the painting system. Because the discharge nozzle is arranged radially around the acquisition area and the detection interface, a fluid flow is provided that surrounds the detection interface laterally and is directed in the direction of the camera's acquisition. As a result of the geometry of the gap, the fluid flow is conical and tapers to a point. This fluid flow, directed away from the detection interface towards the working area, prevents overspray from the painting process from adhering to the detection interface. The conical fluid flow shields the detection interface from paint particles on all sides.This allows the detection interface to be reliably protected from contamination, and cleaning intervals can be greatly extended or cleaning may no longer be necessary at all. The paint booth is enclosed by a cabin housing. The painting process takes place within the work area inside the cabin housing. The paint booth contains at least one painting device, for example, a painting tool guided by a multi-axis robot. The image acquisition device is, for example, a photo or video camera. The image acquisition device can be located outside the booth housing, in which case the detection interface is formed, for example, by a window in the booth housing. Alternatively, the image acquisition device can be located in a separate housing inside the paint booth, in which case the detection interface is, for example, a pane or window in the separate housing, or the lens of the image acquisition device. It is preferred if the nozzle has a continuous annular outlet gap. This allows an uninterrupted annular airflow to be generated at the nozzle outlet, directed away from the detection interface. The outflowing fluid leaves the annular nozzle outlet gap in the manner of a closed annular air curtain, which shields the detection area laterally against the penetration of paint particles. The shape of the nozzle outlet gap is determined by two nozzle boundary surfaces. In one embodiment, these nozzle boundary surfaces are frustoconical. Viewed in the direction of fluid flow, the boundary surfaces are inclined inwards towards the central longitudinal axis of the nozzle. The nozzle boundary surfaces can, for example, be positioned with their conical apex on the central axis of the discharge nozzle. By shaping the nozzle outlet gap with frustoconical boundary surfaces, the generation of a laminar, conical airflow is promoted. The nozzle outlet gap is inclined inwards relative to the nozzle's central longitudinal axis. It has proven particularly effective if the nozzle outlet gap is inclined at an angle of 30 to 60 degrees, and especially at an angle of 40 to 50 degrees, relative to the nozzle's central longitudinal axis. The inclination of the nozzle outlet gap is determined by the inclination of the boundary surfaces that define the nozzle outlet gap. The nozzle has an annular nozzle body. Upstream of the nozzle outlet gap, the nozzle body has an outer and an inner annular distribution chamber, which are interconnected by a multitude of circumferentially uniform openings. A flange with a fluid supply opening is located laterally on the nozzle body, opening into the outer distribution chamber. The fluid flows through the supply opening first into the outer chamber, distributes itself there, enters the inner chamber, and from there into the outlet gap. The openings connecting the outer and inner distributor chambers are preferably designed as slot openings. This slot-like fluid connection between the outer and inner chambers promotes the incoming fluid's initial distribution within the outer chamber before it enters the inner chamber. This equalizes the flow conditions from the outer to the inner chamber along the circumference of the nozzle. It prevents the fluid from flowing significantly faster into the inner chamber and from there into the nozzle outlet gap near the inlet opening than on the opposite side of the distributor chamber. The flow velocities of the fluid into the inner chamber are thus equalized. This effect can be further enhanced if the outer chamber has a larger volume than the inner chamber, e.g., at least twice the volume. By ensuring a uniform flow pattern around the circumference of the inner distributor chamber, the fluid flow from the nozzle outlet gap is also essentially uniform along its circumference. This results in a symmetrical formation of the cone-shaped fluid flow and optimal shielding of the detection interface. To achieve optimal shielding, the nozzle is preferably positioned directly at the detection interface. The nozzle body can, for example, be attached to the wall of the paint booth in the area of ​​the window. In particular, the nozzle body can be designed to seal against the booth wall, preventing air from entering laterally between the nozzle body and the booth wall. The nozzle can be made from either metals or plastics. Machining processes, for example, can be used. However, the nozzle can be manufactured particularly easily and cost-effectively using additive manufacturing, such as 3D printing. Additive manufacturing places virtually no restrictions on the geometry of the component being produced, which means that even the frustoconical boundary surfaces of the nozzle outlet gap can be easily manufactured. Furthermore, a method for operating a paint booth, in particular a paint booth described above, is described, wherein an image acquisition device with its detection range is directed towards a working area in the paint booth by means of a detection interface. An annular nozzle, which is arranged inside the paint booth in front of the detection interface, radially encloses the detection range of the image acquisition device and has an outlet gap inclined in the direction of the central longitudinal axis of the nozzle, is supplied with a fluid flow at least during a painting process taking place in the paint booth. Image acquisition using the image acquisition device can take place during the painting process, or before or after. The design and arrangement of the nozzle, as described above, provides a conical fluid flow that shields the detection interface from contamination on all sides. The nozzle is operated at least during the painting process; however, it can be advantageous to continue operating the nozzle for a certain period of time even after the painting process is complete. In a preferred embodiment, the volume flow rate and pressure of the fluid flow are selected such that the conical fluid flow exiting the nozzle forms a laminar flow extending from the nozzle exit gap to the apex of the conical fluid flow. The laminar flow acts like a protective curtain, reliably keeping the overspray from the painting process away from the detection interface. In principle, any gaseous medium can be used as the fluid. However, for cost reasons, it is advantageous to use air as the fluid. Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. Where the term "can" is used in this application, it refers to both the technical possibility and the actual technical implementation. The following are exemplary embodiments explained with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of an exemplary paint booth, Fig. 2 a sectional view of an exemplary nozzle, and Fig. 3 a partial sectional view of the nozzle from Fig. 2. Fig. 1 shows an exemplary paint booth 1. The paint booth 1 comprises a booth housing 10 in which at least one painting device 12, e.g., in the form of a painting tool guided by an industrial robot, is provided. A component B, such as a vehicle body, is arranged in the working area AB of the painting device 12. The booth housing 10 surrounds and shields the working area AB. This prevents the entry of dust or contaminants into the paint booth 1 and also prevents the escape of overspray. Additional painting devices or handling robots, e.g., for opening the doors and flaps of the vehicle body, can be provided in the paint booth. Outside the cabin housing 10, an image acquisition device 14 in the form of a camera is provided, the camera's detection range EB being directed towards the work area AB and the component B positioned there. The image acquisition device 14 captures images of the component B, which can be used, for example, to control the robots or to measure the component. The image acquisition device 14 looks through a detection interface 16, which is designed as a window in the cabin housing 10. To prevent the window 16 from being contaminated by overspray, an annular nozzle 20 is arranged on the inside of the paint booth 1 in front of the window 16. The annular nozzle 20 is, for example, attached directly to the window 16. The annular nozzle 20 is positioned so that the image acquisition device 14, with its detection area EB, can see through it onto the work area AB. During operation of the painting device 12, an airflow is blown through the nozzle 20 via supply lines (not shown). The airflow is directed from the nozzle into the interior of the paint booth and thus prevents airborne particles, such as overspray, from reaching the window in the paint booth. Fig. 2 shows a sectional view of an exemplary nozzle 20. The nozzle 20 has an annular base body 21. An inner distribution chamber 22 and an outer distribution chamber 23 are provided in the base body, which are fluidically connected to each other by a plurality of slots 24 (see Fig. 3). The fluid is introduced into the base body 21 via a feed nozzle 25 formed on the outer circumference of the base body 21 and initially enters the outer distribution chamber 23. The fluid then passes through the slots 24 into the inner distribution chamber 22 and from there exits the nozzle via a nozzle outlet gap 26. The airflow is symbolically represented by the arrows. The nozzle outlet gap 26 is designed as a continuous, circumferential annular gap. The nozzle boundary surfaces 27, 28 forming the nozzle outlet gap 26 are preferably designed as conically inclined surfaces. The boundary surfaces 27, 28 can each form a frustoconical surface. The nozzle outlet gap 26 is inclined inwards relative to the central longitudinal axis L of the nozzle. The angle α at which the boundary surfaces are inclined inwards relative to the central longitudinal axis is preferably in the range of 30 degrees to 60 degrees and particularly in the range of 40 degrees to 50 degrees. The fluid cone exiting the nozzle is formed at a corresponding angle during operation. The inclined design of the nozzle outlet gap 26 directs the air passing through the gap obliquely inwards, resulting in a cone-shaped airflow in front of the nozzle outlet. This provides all-around shielding of the detection interface or the window 16, which is preferably arranged directly on the base body 21 on the side of the nozzle 20 opposite the nozzle outlet gap 26. Fig. 3 shows a sectioned perspective view of a portion of the nozzle from Fig. 2 to illustrate the chamber structure. The inner distributor chamber 22 and the outer distributor chamber 23 are separated by a circumferential separating web 29. The separating web is interrupted by a plurality of slots 24, which establish a fluidic connection between the two chambers. The slots 24 are evenly distributed along the circumference of the separating web 29. The outer distributor chamber 23 has a chamber volume that is preferably at least twice the chamber volume of the inner distributor chamber 22. This, in combination with the slots, results in a particularly uniform flow towards the nozzle outlet gap 26, so that the fluid flow exiting the nozzle outlet gap is essentially uniform along the circumference of the nozzle. Reference symbol list 1 Paint booth 10 Booth housing 12 Paint application device 14 Image acquisition device 16 Detection interface 20 Annular nozzle 21 Base body 22, 23 Distribution chambers 24 Slots 25 Feed nozzle 26 Nozzle exit gap 27, 28 Nozzle boundary surfaces 29 Separating web AB Working area B Component EB Detection area L Central longitudinal axis of the nozzle α Angle

Claims

Paint booth with a working area (AB), an image acquisition device (14) whose detection area (EB) is directed towards the working area (AB) through a detection interface (16), and an annular nozzle (20) arranged inside the paint booth (1) in front of the detection interface (16), wherein the nozzle (20) radially surrounds the detection area (EB) of the image acquisition device (16) and has a nozzle outlet gap (26) inclined in the direction of the central longitudinal axis (L) of the nozzle (20), wherein the geometry of the nozzle outlet gap is configured to generate a conical and tapered fluid flow directed away from the detection interface towards the working area. Paint booth according to claim 1, wherein the detection interface (16) is a window in a booth housing (10) of the paint booth (1). Paint booth according to one of claims 1 or 2, wherein the nozzle (20) has a continuous annular nozzle outlet gap (26). Paint booth according to one of the preceding patent claims, wherein the nozzle exit gap (26) is limited by two frustoconical nozzle boundary surfaces (27, 28). Paint booth according to one of the preceding patent claims, wherein the angle at which the nozzle exit gap is inclined relative to the central longitudinal axis of the nozzle is in a range of 30 degrees to 60 degrees or in a range of 40 degrees to 50 degrees. Paint booth according to one of the preceding patent claims, in which an inner and an outer annular distribution chamber (22, 23) are arranged upstream of the nozzle exit gap (26) in the fluid direction, which are connected to each other by slot openings (24). Paint booth according to claim 6, wherein the volume of the outer distribution chamber (23) is at least twice as large as the volume of the inner distribution chamber (22). Paint booth according to one of the preceding patent claims, in which the nozzle (20) is arranged directly at the detection interface (16). Paint booth according to one of the preceding patent claims, wherein the nozzle (20) is manufactured from a plastic using a 3D printing process. Method for operating a paint booth (1), wherein an image acquisition device (14) with its detection area (EB) is directed by a detection interface (16) towards a working area (AB) of the paint booth (1) and an annular nozzle (20), which is arranged inside the paint booth (1) in front of the detection interface (16) and which radially surrounds the detection area (EB) of the image acquisition device (14) and has a nozzle outlet gap (26) inclined in the direction of the central longitudinal axis (L) of the nozzle (20), is supplied with a fluid flow at least during a painting process taking place in the paint booth, whereby a conical and tapered fluid flow is directed away from the detection interface towards the working area. Method according to claim 10, wherein the volume flow and the pressure of the fluid flow are selected such that the conical fluid flow exiting the nozzle (20) forms a laminar flow extending from the nozzle exit gap (26) to the tip of the conical fluid flow.

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