EP3552716B1 - Conveyor device for conveying coating powder, powder centre with the conveyor device and a method of cleaning the powder centre - Google Patents

Description

Technical area

The invention relates to a conveying device for conveying coating powder. The invention also relates to a powder center with such a conveying device and a method for cleaning the powder center and a method for cleaning the powder center.

When electrostatically coating workpieces with coating powder, or in short powder, the powder is sprayed onto the workpiece to be coated using one or more powder applicators. The workpiece coated with powder is then heated so that the powder melts. After the workpiece has cooled, the powder forms a hard, closed coating on the workpiece. During the coating process, the workpieces to be coated are usually located within a powder coating booth, which is also referred to below as a booth or coating booth. The powder applicators are supplied with coating powder via one or more powder conveyors, which can be located in a powder center.

If workpieces are to be coated with a different coating powder than the powder previously used, the coating process is interrupted and a so-called powder change is carried out. When changing powder, for example if a different type of powder or powder with a different color is to be sprayed, more or less comprehensive cleaning measures are required in order to remove the remains of the previously used powder from the powder-carrying components of the system. Manually cleaning these components can take some time. During the cleaning process, the system is not available for coating workpieces. This has a negative impact on production costs. Another disadvantage of manual cleaning is that the staff runs the risk of inhaling powder particles during cleaning. It is also important to ensure that cleaning is carried out thoroughly. For example, if the powder conveyor or the powder center is not cleaned sufficiently, undesirable color carryover can occur after a color change.

State of the art

From the European patent application EP 3 238 832 A1 a powder conveying device for conveying coating powder to a powder applicator is known. The powder conveying device has a powder conveyor which is connected to a work container arranged underneath and serves to convey coating powder from a powder storage container into the work container. When changing powder, powder is initially added located in the work container, removed from the work container. For this purpose, a powder line protruding into the work container and a valve are provided. When the valve is open, the remaining powder can be removed from the work container. A possible return container, which is intended to hold the residual powder removed from the work container, must disadvantageously be placed directly below the work container. This means that the work container has to be placed very high up, which can lead to space problems in confined spaces. When the residual powder flows out of the working container or the valve for residual powder, powder dust is created, which pollutes the environment and which then has to be cleaned regularly by hand. In addition, the resulting powder dust can be accidentally inhaled by operating personnel.

From the state of the art DE 10 2014 003 373 A1 a powder coating system is known. The system includes a powder container with a drain valve for residual powder. This system also has the disadvantages described above.

Presentation of the invention

One object of the invention is to provide a conveyor device for conveying coating powder, a powder center with the conveyor device and a method for cleaning the powder center, in which the degree of automation in cleaning is increased even further is increased.

Advantageously, the immission of powder dust can be further reduced with the conveying device according to the invention for conveying coating powder. This minimizes the risk of operating personnel inhaling powder dust while cleaning.

A further advantage of the conveying device according to the invention for conveying coating powder is that the powder storage container or the working container, which is part of the conveying device, no longer has to be lifted by the operating personnel and transported to another location.

In addition, with the conveying device according to the invention for conveying coating powder, the quality of the cleaning can be maintained at a particularly high level and the cleaning can be carried out in a process-reliable manner.

In addition, the automated cleaning provided for the conveyor device according to the invention can be carried out more quickly than if the conveyor device were cleaned by the operating personnel.

A further advantage of the invention is that the conveying device and the powder return container, which is intended to hold the residual powder removed from the working container, do not have to be directly next to each other. The distance between the conveyor device and the powder collection container can be up to 20 or 30 m.

The object is achieved by a conveyor device for conveying coating powder with the features specified in claim 1.

The conveying device according to the invention for conveying coating powder comprises a powder storage container which has a powder outlet and a powder outlet channel at the bottom, the powder outlet being the inlet for the Powder outlet channel forms. The powder outlet channel is connected to a first powder conveyor in order to convey powder from the powder storage container back to a powder container. The powder storage container has a container base and a number of further powder outlets in the area of the container base. In addition, a powder conveying device is provided to convey powder through one of the further powder outlets from the powder storage container to a powder applicator.

The task is also solved by a powder center which includes the conveying device and has the features specified in claim 14.

The powder center according to the invention with the conveying device described above has a cleaning unit for cleaning the powder storage container and the container lid. The cleaning unit can be moved by means of a manipulator from a parking position next to the powder storage container into a cleaning position in the powder storage container. In addition, a control is provided with which the cleaning unit and the manipulator can be controlled.

The object is also achieved by a method for cleaning the powder center described above, the method comprising the features specified in claim 15.

The procedure for cleaning the powder center includes the following steps. The first powder conveyor is used to remove the remaining powder in the powder storage container promoted out. The powder storage container and the container lid are then cleaned using the cleaning unit.

Advantageous developments of the invention result from the features specified in the dependent patent claims.

In one embodiment of the conveying device according to the invention, a third powder conveyor is provided in order to convey powder from the powder container into the powder storage container. This allows the level of automation to be increased even further.

In another embodiment of the conveying device according to the invention, a valve for purging air is provided, which is connected to the powder outlet channel via a purging air inlet and is intended to blow purging air into the powder outlet channel and/or to the first powder conveyor. This has the advantage that cleaning can be carried out even more automatically.

In a further embodiment of the conveying device according to the invention, a fluidizing element is provided in the powder outlet channel. This allows the transport of the remaining coating powder from the work container to be further improved.

In the conveying device according to the invention, the fluidizing element can be annular. Such a fluidizing element can be produced simply and inexpensively. Another advantage is that this fluidizing element can be installed in such a way that no dead space is created and therefore no powder can be deposited there. In addition, such a fluidizing element easy to clean. The air for fluidization can also be distributed evenly over the circumference of the powder channel with such a fluidizing element.

In addition, in the conveying device according to the invention it can be provided that the fluidizing element is made of a microporous material. This means that air can pass through the fluidizing element, but not the coating powder.

In a further development of the conveying device according to the invention, the powder storage container has a circular cross section. This has the advantage that the powder storage container has fewer corners and edges in which powder can accumulate. The powder storage container is therefore easier to clean.

In another development of the conveying device according to the invention, the powder storage container has a bottom that slopes downwards towards the center of the powder storage container. Gravity can be used to help collect and transport the remaining powder.

In an additional development of the conveying device according to the invention, the mouth of the powder outlet channel is located in the middle of the sloping floor. This allows the removal of residual powder to be further improved.

Advantageously, in the conveying device according to the invention, the powder outlet channel is funnel-shaped. This can also further improve the removal of residual powder.

It is also possible for the first powder conveyor in the conveying device according to the invention to have a powder container with a powder inlet and a powder outlet, as well as a powder inlet valve and a powder outlet valve. The powder inlet is connected to the powder inlet valve and the powder outlet is connected to the powder outlet valve. The powder container can be placed under negative pressure.

In one embodiment of the conveying device according to the invention, the third powder conveyor is constructed like the first powder conveyor.

In another embodiment of the conveying device according to the invention, a container lid is provided on the powder storage container, which is at least partially removable.

Brief description of the drawings

Figur 1

zeigt eine erste mögliche Ausführungsform der erfindungsgemässen Fördervorrichtung zum Fördern von Beschichtungspulver, teilweise im Längsschnitt und teilweise als Blockschaltbild.

Figur 2

zeigt eine mögliche Ausführungsform eines Pulverförderers teilweise im Längsschnitt.

Figur 3

zeigt in einem schematischen Blockschaltbild eine mögliche Ausführungsform einer Pulverbeschichtungsanlage mit der erfindungsgemässen Fördervorrichtung.

Figur 4

zeigt eine erste mögliche Ausführungsform des erfindungsgemässen Pulverzentrums im Pulverfördermodus in einer ersten dreidimensionalen Ansicht.

Figur 5

zeigt die erste Ausführungsform des erfindungsgemässen Pulverzentrums in einer zweiten dreidimensionalen Ansicht.

Figur 6

zeigt das erfindungsgemässe Pulverzentrum in der Draufsicht.

Figur 7

zeigt das erfindungsgemässe Pulverzentrum in einer ersten Seitensicht.

Figur 8

zeigt einen Teil des erfindungsgemässen Pulverzentrums mit der Siebreinigungsvorrichtung von der Seite in einer vergrösserten Ansicht im Schnitt.

Figur 9

zeigt einen weiteren Teil des erfindungsgemässen Pulverzentrums mit der Behälterreinigungseinrichtung von der Seite in einer vergrösserten Ansicht im Schnitt.

Figur 10

zeigt das erfindungsgemässe Pulverzentrum im Reinigungsmodus in einer ersten dreidimensionalen Ansicht.

Figur 11

zeigt das erfindungsgemässe Pulverzentrum im Reinigungsmodus in einer zweiten dreidimensionalen Ansicht.

Figur 12

zeigt das erfindungsgemässe Pulverzentrum im Reinigungsmodus in der Draufsicht.

Figur 13

zeigt eine mögliche Ausführungsform einer Frischpulverstation in einer dreidimensionalen Ansicht.

Figur 14

zeigt die Frischpulverstation in der Ansicht von vorne.

Figur 15

zeigt die Frischpulverstation in der Seitenansicht im Schnitt.

Figur 16

zeigt die Frischpulverstation in der Draufsicht im Schnitt.

The invention is further explained below with several exemplary embodiments using 16 figures.

Figure 1

shows a first possible embodiment of the conveying device according to the invention for conveying coating powder, partly in longitudinal section and partly as a block diagram.

Figure 2

shows a possible embodiment of a powder conveyor, partially in longitudinal section.

Figure 3

shows a schematic block diagram of a possible embodiment of a powder coating system with the conveyor device according to the invention.

Figure 4

shows a first possible embodiment of the powder center according to the invention in the powder conveying mode in a first three-dimensional view.

Figure 5

shows the first embodiment of the powder center according to the invention in a second three-dimensional view.

Figure 6

shows the powder center according to the invention in a top view.

Figure 7

shows the powder center according to the invention in a first side view.

Figure 8

shows part of the powder center according to the invention with the screen cleaning device from the side in an enlarged view in section.

Figure 9

shows another part of the powder center according to the invention with the container cleaning device from the side in an enlarged view in section.

Figure 10

shows the powder center according to the invention in cleaning mode in a first three-dimensional view.

Figure 11

shows the powder center according to the invention in cleaning mode in a second three-dimensional view.

Figure 12

shows the powder center according to the invention in the cleaning mode in a top view.

Figure 13

shows a possible embodiment of a fresh powder station in a three-dimensional view.

Figure 14

shows the fresh powder station in front view.

Figure 15

shows the fresh powder station in a side view in section.

Figure 16

shows the fresh powder station in a top view in section.

Ways of carrying out the invention

In Figure 1 A first possible embodiment of the conveying device according to the invention for conveying coating powder is shown. Some components of the conveyor device are shown in longitudinal section and some symbolically as a block diagram. The conveying device includes a powder storage container 3, which has a Container lid 23 can be closed. The powder storage container 3 and the container lid 23 together form a working container 3, 23. If necessary, the container lid 23 can have a side wall 23.2. The container lid 23 then has the shape of an upside down pot.

At the in Figure 1 In the embodiment shown, a powder conveyor 4 is located above the working container 3, 23 in order to convey powder from a powder container 111 into the powder storage container 3 or into the working container 3, 23.

The powder storage container 3 can have a circular cross section. Inside the powder storage container 3 can, as in Figure 1 shown, a sieve 24 may be arranged. The sieve 24 is preferably designed as an ultrasonic sieve.

A fluidizing base 25.1 can be located in the lower area of the powder storage container 3. The powder storage container 3 is closed at the bottom with a bottom 25. In a preferred embodiment, the fluidizing base 25.1 is arranged directly above the base 25 and slopes obliquely towards the center of the powder storage container 3 or towards a powder outlet 25.2.

The powder outlet 25.2 serves as an outlet for residual powder and forms the inlet mouth of a powder outlet channel 203. This is preferably funnel-shaped and has a fluidizing element 201. The fluidizing element 201 can be annular and made of a microporous material. The fluidizing element 201 can be tubular, for example. The inlet opening 25.2 of the powder outlet channel 203 is preferably located in the middle of the sloping fluidizing base 25.1.

In one embodiment of the conveying device, a vibrator 220 is provided, which can be located, for example, below the powder storage container 3 (see Figure 1 ). With the help of the shaking movements generated by the shaker 220, the powder-air mixture in the powder storage container 3 can be fluidized even more evenly. In addition, the powder-air mixture can flow out of the powder outlet channel 203 even more optimally.

The powder outlet channel 203 has a purge air inlet 212 at the bottom, via which it is connected to a valve for purge air S12. The purge air valve S12 in turn is connected to a compressed air source via connection 3.3.

The purge air valve S12 can be used for purging in two different ways. On the one hand, it can blow flushing air into the powder outlet channel 203 via the flushing air inlet 212 for cleaning purposes. For this purpose, the material valve M11 is opened, the inlet valve 49.2 and possibly also the outlet valve 49.3 of the powder conveyor 49 are closed. The suction of the cleaning device 28 is switched on. When the purge air valve S12 is now opened, the compressed air flows from bottom to top through the powder channel 203 and cleans it. On the other hand, the purge air valve S12 can also be used to blow purge air via the line 96 and the powder conveyor 49 in the direction of the suction opening 162. In addition the material valve M11 is closed. The inlet valve 49.2 and the outlet valve 49.3 of the powder conveyor 49 are opened. The suction at the suction opening 162 is switched on.

On the outlet side, the powder channel 203 is connected to connection 3.4 via a valve M11. A line 96 can be connected to the connection 3.4, via which the residual powder that is still in the powder storage container 3 can be transported back to a powder storage container 110 using a powder conveyor 49. The powder storage container 110 can be part of a fresh powder station 3 (see Figures 13 - 16 ). The line 96 can be designed as a hose.

Figure 2 shows a possible embodiment of the powder conveyor 49 for conveying coating powder, partly in longitudinal section. The powder that can be conveyed with the powder conveyor 49 can be, for example, fresh powder or recycled powder.

The powder conveyor 49 has a powder inlet valve 310 with a powder inlet 310.1 on the input side. When the powder inlet valve 310 is open, powder can be sucked or pumped into a container 301 adjoining the powder inlet valve 310. The container 301 is also referred to below as an intermediate container. It has a container housing or, in short, housing with an upper housing part 302, a housing middle part 303 and a lower housing part 304.

The powder inlet valve 310 can be designed as a squeeze. To open the powder inlet valve 310, the Control port 313.1 of valve 313 depressurized. The valve 313 is preferably designed as a quick vent valve. This means that if necessary, the pressure in the powder inlet valve 311 can be reduced more quickly and its valve opening time can be shortened.

The powder conveyor 49 has a powder outlet valve 320 on the output side with a powder inlet 320.1 and a powder outlet 320.2. The powder outlet valve 320 can be designed as a squeeze. In order to open the powder outlet valve 320, the control connection 323.1 of the valve 323 is depressurized. Like the valve 313, the valve 323 can also be designed as a quick vent valve. This means that the pressure in the powder outlet valve 320 can be reduced more quickly if necessary.

Like in the Figures 1 and 2 shown, the upper housing part 302 has a funnel-shaped inside 302.1. The funnel-shaped contour helps to channel the powder flowing into the intermediate container 301 without it sticking to the inner wall of the upper housing part 302. In the lower area of the upper housing part 302, the funnel-shaped inside 302.1 is adjoined by a paragraph 302.2, which is also referred to below as the upper paragraph. The paragraph 302.2 is an annular surface which preferably runs slightly obliquely relative to the horizontal. The paragraph 302.2 is adjoined by an inner wall 302.3, which preferably deviates slightly from the vertical.

When the upper end of the tube 305 is pushed in the direction of the paragraph 302.2, the side wall 302.3 forms a guide that tapers towards the top and thus acts as a centering aid for the tube 305 Side wall 302.3 is followed by a wide paragraph below and then another side wall 302.5.

The lower end of the upper housing part 302 is designed as a round connector 302.7. The housing middle part 303 is plugged onto this connector 302.7, which carries a seal. With the help of several screws 309, the middle part of the housing 303 can be screwed to the upper part of the housing 302. The lower end of the middle housing part 303 is located in an annular receptacle of the lower housing part 304.

The lower housing part 304, like the upper housing part 302, has a funnel-shaped inside 304.1. The funnel-shaped contour helps to channel the powder located in the intermediate container 301 towards the outlet 320.1 without it sticking to the inner wall 304.1 of the lower housing part 304. In the upper area, a paragraph 304.2 adjoins the funnel-shaped inside 304.1. The paragraph 304.2 is also referred to below as the lower paragraph and is an annular surface that is slightly slanted compared to the horizontal.

When the tube 305 is pushed with its lower end in the direction of the lower paragraph 304.2, the side wall 304.3 forms a guide that tapers downwards and thus acts as a centering aid for the tube 305. Another paragraph adjoins the side wall 304.3 above and to it again another side wall 304.5.

The side wall 304.5, like the side wall 302.5, is spaced from the outside 305.9 of the tube 305, so that between the side walls 302.5, 304.5 and the outside of the tube 305 a free space 306 is created. In the area of the free space 306, the air can pass through the semi-permeable tube 305, but not the powder.

The upper end of the lower housing part 304 is preferably designed as a round socket 304.7 and forms a receptacle for the lower section of the middle housing part 303. The lower section of the middle housing part 303 is in the receptacle and can be screwed and/or glued to it. This creates a secure and tight connection between the middle housing part 303 and the lower housing part 304 in a simple manner.

If the powder conveyor 49 is to be used in an area with an increased risk of explosion, grounding can be provided on the powder conveyor. The ground cable 314 may, for example, be electrically connected to the housing middle part 303 of the powder conveyor 49.

The powder conveyor 4, which serves to supply the working container 3, 23, can be identical in construction to the powder conveyor 49. The operation of the powder conveyor 4 is explained further below. It is assumed that the intermediate container 301 is initially free of powder. In a first step, the valves 310 and 320 are closed so that neither powder gets into the intermediate container 301 nor is powder transported out of the intermediate container 301. Now the vacuum valve 327 is opened to generate a negative pressure in the intermediate container 301. The air is sucked out of the intermediate container 301 through the air-permeable pores of the tube 305. As soon as the powder inlet valve 310 is opened, powder is fed into the intermediate container 301 respectively the powder chamber 307 is sucked. There is no need to wait until a certain negative pressure is built up in the intermediate container 301. The powder inlet valve 310 can be opened at any time, i.e. shortly before the opening of the vacuum valve 327, simultaneously with the vacuum valve 327 or even after the vacuum valve 327 has been opened. When sufficient powder has accumulated in the powder chamber 307 of the intermediate container 301, the vacuum valve 327 and the powder inlet valve 310 are closed again. Such a suction process can take, for example, 6 seconds. The outlet valve 320 is then opened so that the powder can flow out of the intermediate container 301. This can be done using gravity. In order to support the powder transport from the intermediate container 301, compressed air can be blown into the intermediate container 301 via the connection 308 and the opening 308.1. To do this, valve 328 is opened. The compressed air first enters the room 306 via the connection 308 and the opening 308.1. It then flows through the semi-permeable tube 305 into the powder chamber 307. The compressed air helps to clean the inner wall of the tube 305 with each conveying cycle.

The connection 308 can be as in Figure 2 shown, are located in the middle part of the housing 303. The connection 308 is connected to the space 306 via the opening 308.1, which is designed as a through hole in the middle part of the housing 303.

The powder conveyor 4 can, as in Figure 1 and 3 shown, be connected to the work container 3, 23 in order to supply it with powder. Since the working container 3, 23 is permanently under pressure during conveying operation, it is advantageous if the pressure in the intermediate container 301 is greater or at least as great as the pressure in the working container 3, 23. A pressure control valve 340 can be used to adjust the pressure in the intermediate container 301. As soon as the powder has flowed out of the intermediate container 301, the outlet valve 320 and the valve 328 are closed again. The intermediate container 301 can then be filled with powder again in the manner described above.

The powder conveyor 4 can have a flange 324. The flange 324 and the screws 325 serve to be able to connect the powder conveyor 4 to another component.

The powder conveyor 4 described above can be used at various points in a powder coating system. Figure 3 shows a possible embodiment of a powder coating system with three such powder conveyors in a schematic block diagram. They are designated as powder conveyors 4, 5 and 49 in the powder coating system. When we talk about the powder conveyor 5 below, this means the entirety of the intermediate container in the narrower sense, the inlet valve and the outlet valve. The same applies to the powder conveyor 49. Its intermediate container is in Figure 1 with the reference number 49.1, its inlet valve marked 49.2 and its outlet valve marked 49.3.

The following describes the structure of the entire powder coating system based on the Figures 3 to 16 explained further.

The powder center 1, which is also referred to as a powder supply device, powder center or integrated powder management system, includes the powder storage container 3, which is used to store the coating powder. In addition, the powder center 1 includes a powder conveying device with which the powder is conveyed out of the powder storage container 3 and transported to a powder applicator 80. In the present case, the powder conveying device is integrated into the powder storage container 3 and will be explained in more detail later. The powder applicator 80 (see Figure 3 ) can be designed as a manual or automatic powder spraying device and has a spray nozzle or a rotary atomizer at its outlet directed towards the workpiece 65.

The powder center 1 is constructed as a module. This allows the powder center 1 to be transported quickly and easily as a compact unit. The individual components of the powder center 1 are attached to frame profiles 2, which can be made of aluminum or steel, for example. The frame profiles 2 form the outer boundary of the powder center 1. If necessary, the powder center 1 can have a base 7.

The powder storage container 3 of the powder center 1 can be arranged on a base 6, for example. Like for example in Figure 9 shown, the powder storage container 3 can be closed with the powder container lid 23 during conveying operation. At the in the Figures 4 to 12 In the embodiment shown, the powder container lid 23 has the shape of an upside-down pot. The powder container lid can be opened using pneumatic locks 18 23 must be sealed tightly with the powder storage container 3. For this purpose, the powder storage container 3 has seals and locking receptacles 3.1, into which correspondingly designed counterparts of the pneumatic lock 18 can engage. The pneumatic lock 18 can be equipped, for example, with a cylinder, a piston and a piston rod. When the lower chamber of the cylinder is pressurized with compressed air, the piston and thus also the piston rod are pushed upwards. The claw located at the lower end of the piston rod engages in the locking receptacle 3.1 and causes the powder container lid 23 to be pressed onto the powder storage container 3. In one embodiment, three such locks 18 are present (for example in the Figures 6 and 7 shown). The number of locks 18 and their structure can easily be adapted to the respective needs.

Inside the powder storage container 3 there is the sieve 24, which can be designed as an ultrasonic sieve. The ultrasonic transducer 24.1 of the sieve 24 is preferably located outside the powder storage container 3. If the powder container lid 23 is removed, the sieve 24 is accessible and can be removed. So that this can happen automatically, the ultrasonic sieve 24 is attached to a pivoting mechanism 16 via a support arm 22. The sieve 24 can be moved out of the working position using the pivoting mechanism 16 (see Figure 6 ) are pivoted out and brought into a cleaning position in a cleaning station 27 (see Figure 12 ). The cleaning station 27 is also referred to below as a screen cleaning device or screen cleaning station.

As in Figure 8 is shown, there is a rotatably mounted cleaning arm 20 inside the cleaning station 27. The cleaning arm 20 has a plurality of cleaning nozzles 20.1 which are arranged on the top of the cleaning arm 20. The cleaning station 27 also includes a lid 15, which can be opened and closed, for example with the help of a pneumatic cylinder 17. The lid 15 is pivoted about a hinge 21. A curved double arrow indicates the pivoting movement. On its underside, the lid 15 carries a cleaning arm 19, which is also equipped with a large number of cleaning nozzles 19.1. The cleaning nozzles 19.1 are preferably located on the underside of the cleaning arm 19. They are aligned so that they blow compressed air downwards onto the ultrasonic sieve 24 located under the cleaning arm 19 during the cleaning operation. The upper cleaning arm 19 is rotatably mounted on the cover 15 with a bearing 50. The lower cleaning arm 20 is rotatably mounted on the cleaning container 14 via a bearing 51. The two bearings 50 and 51 can also be designed as air motors. The direction of rotation of the upper cleaning arm 19 and the direction of rotation of the lower cleaning arm 20 are each marked with an arrow. The direction of rotation of the cleaning arm results from the offset arrangement of the cleaning nozzles and the recoil that occurs when compressed air flows out through the nozzles. During the cleaning operation, the ultrasonic sieve 24 is located between the lower cleaning arm 20 and the upper cleaning arm 19.

The cleaning arm 19 can be at both ends (as in Figure 8 shown) must be angled so that it is horizontal Legs and two legs pointing diagonally upwards. The compressed air nozzles 19.1 can be located both on the horizontal leg and on the legs directed obliquely upwards. The cleaning arm 19 can be designed as a tube in order to guide the compressed air inside the tube to the compressed air nozzles 19.1. The same applies to the lower cleaning arm 20, even if in Figure 8 the ends of the lower cleaning arm 20 are not angled.

On the underside of the container 14 for receiving the sieve 24 there is a lower container section 14.2 with an outlet 14.1. The powder-air mixture located in the cleaning station 27 can be sucked out via the outlet 14.1. For this purpose, the outlet 14.1 is connected to an inlet opening 13.2 of a suction pipe 13 via a hose (not shown in the figures). The powder-air mixture can be sucked into a secondary filter 100 via the suction pipe 13 and a suction line 91.

The powder inlet of the working container 3, 23 is preferably located in its upper area. It can be arranged, for example, in the powder container lid 23 of the working container 3, 23. The working container 3, 23 can also have several powder inlets. The powder inlet 23.1 is connected to the powder outlet 4.2 of the intermediate container 301 via the powder valve M21, which is designed, for example, as a pneumatically controlled squeezer. The intermediate container 301, together with the inlet valve M20 and the outlet valve M21, serves as a powder conveyor 4 and is usually arranged above the working container 3, 23. In this way gravity can can be used to transport powder located in the intermediate container 301 downwards into the working container 3, 23.

A second powder conveyor 5 can be arranged above the working container 3, 23. Its powder outlet also opens into the working container 3, 23. The second powder conveyor 5 can be constructed like the first powder conveyor 4 (see Figure 2 ).

The powder conveying device integrated into the powder storage container 3 is explained in more detail below. The powder conveying device can, as in the European patent application EP 3 238 832 A1 described, trained. The working container 3, 23 is designed and operable in such a way that it can be pressurized. With the help of the powder conveyor 4, powder can be conveyed out of the fresh powder station 30 and transported into the work container 3, 23. There is a corresponding powder inlet in the powder container lid 23, which covers the top of the powder storage container 3. The working container 3, 23 has in the area of the container base 25 a fluidizing insert 25.1 for fluidizing the powder and a series of powder outlets 3.2. It can be provided that a powder outlet valve G1 - G36 is connected to each of the powder outlets 3.2. A powder line 81 is connected to each of the powder outlet valves G1 - G36. Each of the powder lines 81 also has an inlet for transport air on the input side, i.e. near the respective powder outlet valve G1 - G36. On the output side, each of the powder lines 81 is preferably connected to one of the powder applicators 80 via a coupling 130.

The amount of powder to be conveyed is controlled by repeatedly opening and closing the respective powder outlet valve G1 - G36 using a controller 70. In order to avoid repetitions, reference is made to the above-mentioned patent application EP 3 238 832 A1 referred.

For this purpose, the coupling 130 has a first group of connections 131 and a second group of connections 132. The control 70 can be used to set which connection of the first group 131 is connected to which connection of the second group 132. One of the powder lines 81 can be connected on the output side to a connection of the first group 131. A powder line can be connected to each connection of the second group 132, which on the other hand is connected to one of the powder applicators 80.

In one embodiment, 36 powder outlet valves G1 - G36 are used. However, more or fewer powder outlet valves can also be used. The number of powder outlet valves used depends on the number of powder applicators 80 used.

As an alternative to the integrated powder conveying device just described with the powder outlet valve G1, a powder injector that works according to the Venturi principle or a powder pump for dense phase conveying can also be provided.

Instead of the powder conveyor 4, a powder pump for dense phase conveying, a hose pump or a powder injector can also be provided. The same applies to the powder conveyor 5.

The powder storage container 3 and its powder container lid 23 as well as the two powder conveyors 4 and 5 are attached to a vertical linear axis 12, which is also referred to as a linear lifting device, and can therefore be moved up and down. The drive 12.1 of the linear axis 12 can be located at the top of the linear axis 12. The vertical double arrow in Figure 9 indicates its direction of movement.

The powder center 1 also includes a container cleaning unit 28 or, in short, cleaning unit, which includes a cleaning container 10, an upper cleaning arm 11 and a lower cleaning arm 26. The upper cleaning arm 11 and the lower cleaning arm 26 are rotatably mounted in the cleaning container 10 and each have a plurality of cleaning nozzles 11.1 and 26.1 operated with compressed air. The cleaning container 10 is attached to a linear lifting device 9 and can be moved vertically up and down (in the y direction) with this. The vertical double arrow in Figure 9 indicates its direction of movement. The drive 9.1 of the linear lifting device 9 can be located at the top of the linear lifting device 9. The linear lifting device 9 in turn is attached to a horizontally aligned linear drive 8 (also called a linear axis) and can be moved back and forth horizontally (in the x direction) with this. The drive 8.1 of the linear axis 8 can be arranged laterally on the linear axis 8 be. With the linear axis 8 it is possible to position the container cleaning unit 28 laterally next to the working container 3, 23 during conveying operation (see Figures 4 to 7 ). During the cleaning operation, the container lid 23 is first moved upwards; Then the container cleaning unit 28 can be positioned with the help of the two linear drives 8 and 9 in such a way that the cleaning container 10 is first brought over the powder storage container 3 and then lowered, to such an extent that the cleaning arm 26 has a defined distance from the bottom 25 of the powder storage container 3 having. The cleaning arm 26 protruding from the bottom of the cleaning container 10 is then located inside the powder storage container 3 and is used to clean the inner wall and the bottom 25 of the powder storage container 3.

With the help of the linear drive 12, the powder container lid 23 can be lowered to such an extent that the inner surfaces of the powder container lid 23 can be blown off and thus cleaned with the cleaning arm 11 protruding from the top of the cleaning container 10. The cleaning arm 11 protrudes into the interior of the powder container lid 23.

A possible embodiment of the fresh powder station 30 is in the Figures 13 to 16 shown in different views.

The fresh powder station 30 can, for example, be designed as an independent module. The station comprises a first footprint 31 and a second footprint 32, each of which contains a powder box 110, 111 (see Figure 3 ) be able to record. The two storage areas 31 and 32 are preferably arranged at an angle so that the powder moves diagonally downwards into a corner in the powder box with the support of gravity. This means that the powder box can be emptied completely or almost completely using a suction lance 33 without much effort. The suction lance 33 is, as in the Figures 15 and 16 shown, can be moved horizontally using a linear drive 44, so that it can be used both for a powder box arranged on the first footprint 31 and for a powder box arranged on the second footprint 32. Furthermore, the fresh powder station 30 has an additional linear drive 38 in order to be able to move the suction lance 33 vertically.

There is a shaker 54 and a scale 46 under the storage area 31 for the powder box 110. The shaker 54 serves to set the powder in the box 110 in motion so that it is better distributed and flows towards the suction lance 33.

The filling level in the box 110 can be determined via the scales 46, and if the filling level falls below a certain level, a change of the powder boxes can be initiated. In addition, the measurement signal generated by the scale 46 can be used to determine whether there is still enough space in the box 110 when powder is to be conveyed via line 96 from the powder center 1 back to the powder station 30.

There is also a vibrator 55 and a scale 47 under the footprint 32. Their purpose corresponds to the same as the vibrator 54 and the scales 46 in the footprint 31.

In order to be able to clean the suction lance 33, the fresh powder station 30 additionally has a cleaning station 52, which is equipped with a scraper ring and/or compressed air nozzles and/or a suction system. This means that the outside of the suction lance 33 can be freed from powder adhering to it during the up and down movement.

In addition, air nozzles 57 can be attached to the cleaning station 53 in order to clean the lower area of the suction lance 33. If the suction lance 33 has a fluidizing crown to fluidize the powder in the suction area, this can also be cleaned with it.

Instead of two shelves 31 and 32 with two powder boxes 110 and 111, only one shelf 32 and a powder container 150 with a fluidizing device could be installed. With, for example, two pumps 124 and 125, powder can be conveyed from a BigBag 121 into the powder container 150 via one powder line 127 each.

Instead of the BigBag 121 or in addition to it, a BigBag 120 with a pump 123 can also be provided. The powder can be pumped from the pump 123 directly to the powder conveyor 4 via a powder line 126.

The BigBag 120 or 121 is also known as a Flexible Intermediate Bulk Container or FIBC for short. It usually contains larger amounts of powder than the powder box 110 and the powder box 111. The BigBag 120/121 is also usually further away from the powder conveyor 4 than the powder box 110 or 111. So The BigBag 120/121 can be at a distance of, for example, 30m from the powder conveyor 4, whereas the powder box 110 or 111 is, for example, 5m away from the powder conveyor 4.

The fresh powder station 30 can have several compressed air control valves 39 and 40 and control buttons 41 and 42. The compressed air control valve 39 can be provided for adjusting the fluid air of the fluid base of the powder container 150. The compressed air control valve 40 is used to adjust the fluid air at the fluidizing crown of the suction lance 33. The position of the exhaust air flap can be controlled using the adjusting button 41. A confirmation signal can be transmitted to the controller via the control button 42.

In the floor area, the fresh powder station 30 can have a suction 37 with a suction opening 37.1 in order to be able to suction excess powder from the interior of the fresh powder station 30. The fresh powder station 30 can also have a flexible suction hose that can be used for manual cleaning if necessary.

It can be provided that the fresh powder station 30 has a pivoting mechanism 45 for the powder conveyor 49. The pivoting mechanism 45 has a drive, which can be designed, for example, as a pneumatic drive, and a pivot arm 45.1. With the help of the pivoting mechanism 45, the powder conveyor 49 can be moved out of the conveying position (see Figure 15 ) be brought into a cleaning position. In the cleaning position, the powder conveyor 49 projects into the interior of the fresh powder station 30. In addition, air nozzles 56 can be provided, to clean the lower portion of the powder conveyor 49 when it is pivoted from the conveying position to the cleaning position or from the cleaning position to the conveying position.

The pneumatic drive can include two pneumatically driven cylinders. The powder conveyor 49 can thus be brought into a cleaning position, a first conveying position and a second conveying position. To move the powder conveyor 49 into the cleaning position (see Fig. 15 ), cylinder 1 and cylinder 2 are retracted. In the first conveying position, the powder conveyor 49 is located above the footprint 31. For this purpose, cylinder 1 is retracted and cylinder 2 is extended. In the second conveying position, the powder conveyor 49 is above the footprint 32; cylinders 1 and 2 are extended. In the first conveying position, powder can be conveyed back into the powder box 110 and in the second conveying position, powder can be conveyed back into the powder box 111.

The suction lance 33 can be brought into three different positions with the linear axis 38 and the linear drive 44: In the cleaning position (see Fig. 13 ), the suction lance 33 is located in the cleaning station 53. In the first conveying position, the suction lance 33 is above the footprint 31 and in the second conveying position above the footprint 32.

If necessary, the fresh powder station 30 can also be equipped with its own control 43. With the help of this control 43, for example, the suction lance 33, which Cleaning station 52 for the suction lance 33, the linear axis 38, the linear drive 44, the pivoting mechanism 45 and the blowing nozzles 56 and 57 are controlled.

The one in the, for example Figures 14 and 16 Powder conveyor 49 shown is advantageously positioned directly above the powder box 110 or 111 into which it is intended to convey powder back. Since it uses gravity, the powder falls into the powder box located under the powder conveyor 49 after the outlet valve 49.2 of the powder conveyor 49 is opened.

The powder conveyor 49 used to return the powder can also be designed differently. For example, it can be designed as a powder pump. Since gravity is not used in such a powder pump, it can be arranged in different locations. For example, it can also be at the same height as the powder box 110.

On the top of the powder station 30, two covers 35 and 36 can be provided, which can be opened manually. This means that the staff also has access to the interior of the fresh powder station 30 from above.

If necessary, the fresh powder station 30 can also be equipped with side walls 34 and a rear wall 48.

A possible embodiment of an entire system for powder coating workpieces 65 is shown in Figure 3 shown in simplified form as a block diagram. The entire system can be controlled via a central control 70. The controller 70 can be connected to various components of the entire system via corresponding control lines (not shown in the figures) and provided to control the powder coating booth 60 including powder applicators 80, the fresh powder station 30, the powder center 1, the powder recovery 90 and/or the post-filter 100 to control.

Alternatively or in addition to the central control 70, as already mentioned above, the fresh powder station 30 can have a separate control 43. The same applies to all other components of the entire system for coating workpieces with powder.

Since not all of the powder particles sprayed by the powder applicators 80 stick to the workpieces 65 to be coated during the coating process, the excess powder, which is also referred to as overspray, must be removed from the cabin 60 again. On the one hand, this is necessary because the environment outside the cabin must be kept free of powder dust. On the other hand, the risk of explosion increases if a certain powder concentration is exceeded due to the cloud of powder dust floating in the cabin. This must be avoided.

The overspray resulting from the coating is sucked out of the cabin 60 as a powder-air mixture together with the air in the cabin 60 and fed to a powder recovery device 90 via a residual powder pipeline 92. The powder recovery device 90 can be designed, for example, as a cyclone. The powder recovered there can be used if necessary be fed back to the powder center 1 via a powder line 94. In order to filter out the portion of the powder that was not filtered out in the cyclone 90, the powder-air mixture can be fed from the cyclone to the after-filter 100 via a suction line 93.

The powder-air mixture in the residual powder pipeline 92 is also referred to as the residual powder air flow. In order to extract the overspray from the cabin 60, the cabin 60 has, for example, a suction slot. It connects the interior of the cabin 60 with the residual powder pipeline 92. Excess powder is sucked out of the cabin interior as a powder-air mixture via the suction slot and the suction pipe 61 and fed to a cyclone separator 90 or, in short, cyclone, which can be designed as a monocyclone. The powder-air mixture flows tangentially into the cyclone 90 and spirals downwards in the cyclone. The powder particles are pressed outwards onto the outer wall of the cyclone 90 by the centrifugal force generated by the rotation of the powder air flow. The powder particles are conveyed downward towards the powder outlet of the cyclone and collected there. The air freed from the powder particles is sucked out via the vertical central tube located in the cyclone 90. The air stream cleaned in this way is often fed to a secondary filter 100 in order to filter out the remaining powder that remains in the air. The powder recovered in the cyclone 90 can be used again for coating and fed to the powder center 1 via the powder line 94.

Conveying mode/conveying operation

During conveying operation, the ultrasonic sieve 24 is located in the work container 3, 23 between the powder storage container 3 and the powder container lid 23. The locks 18 ensure that the work container is sealed airtight. The screen cleaning device 27 and the container cleaning unit 28 are located as in the Figures 4 to 7 shown in the parking position.

The parking position for the container cleaning unit 28 is located next to the powder storage container 3. The phrase “next to the powder storage container” also includes above, below, in front of or behind the powder storage container.

The sieve 24 is not absolutely necessary for the conveying operation. The powder can also be conveyed without an ultrasonic sieve or without a sieve 24 at all.

Cleaning mode/cleaning operation

In order to switch from conveying mode to cleaning mode, the powder conveyance from the powder storage container 3 is stopped and the remaining powder still in the powder storage container 3 is sucked off with the powder conveyor 49 via the outlet 25.1 and the line 96. The material valve M11 is opened for this purpose, the flushing valve S12 is closed during this time. The excess pressure still prevailing in the working container 3, 23 is reduced to normal pressure and the locks 18 are opened.

Then the powder container lid 23 is raised with the aid of the linear lifting device 12 and the ultrasonic sieve 24 is pivoted from the working position into the cleaning position with the aid of the pivoting mechanism 16.

Like in the Figures 10 to 12 shown, the linear drive 12 lifts the container lid 23 so far that the cleaning container 10 can be moved between the powder container lid 23 and the powder storage container 3 with the help of the two linear axes 8 and 9. The container cleaning unit 28 with the cleaning container 10 is then lowered until the lower cleaning arm 26 is located inside the powder storage container 3 and has a defined distance from the bottom 25 of the powder storage container 3.

The powder container lid 23 is now lowered until the upper cleaning arm 11 is inside the powder container lid 23 and has a defined distance from the powder container lid 23.

In the above embodiment, an air gap remains between the powder container lid 23 and the cleaning container 10. An air gap also remains between the powder container 3 and the cleaning container 10. Air is sucked in from the afterfilter 100 through the air gaps. This prevents the powder-air mixture generated by the compressed air nozzles 11.1 and 26.1 during the cleaning process from escaping into the environment.

Instead, it is also possible to lower the powder container lid 23 to such an extent that there is no longer a gap between the powder container lid 23 and the cleaning container 10. The gap between the cleaning container 10 and the powder container 3 can also be eliminated if the cleaning container 10 is lowered until it rests on the powder container 3.

In a further embodiment, the unit consisting of the powder container lid 23, cleaning container 10 and powder storage container 3 can be sealed airtight with the locks 18.

In a next step, compressed air is blown through the nozzles 11.1 and 26.1 in the direction of the inner walls of the powder container lid 23 and the powder storage container 3. The resulting powder-air mixture is sucked off via the suction line 13 and can be fed to the cyclone 90 and/or the secondary filter 100.

The powder conveyor 4 can be cleaned as follows. With a flushing valve S13 (see Figure 3 ), compressed air is preferably blown intermittently into the powder inlet valve M20 and through the powder conveyor 4 towards the powder outlet valve M21. The compressed air is sucked out through the suction 13 in the direction of the after-filter 100. In addition, compressed air is supplied at the same time via valve 328 (see Figure 2 ) is blown through the porous wall of the tube 305 and the tube 305 is blown free of powder dust from the outside to the inside. For the cleaning process, the compressed air value on the pressure regulator 340 is significantly increased, for example to 5 bar. This means that significantly more compressed air flows and cleaning becomes more efficient.

In principle, the powder conveyor 5 can also be cleaned in the manner described above.

The two powder conveyors 4 and 5 can be operated via a material valve M22 (see Figure 3 ) be connected. If the material valve M22 is controlled accordingly, the two powder conveyors 4 and 5 can be cleaned via a single flushing valve S13. Instead, the powder conveyor 4 can also be cleaned via a first flushing valve and the powder conveyor 5 can be cleaned via a second flushing valve.

The powder conveyor 49 can also be cleaned in the manner described above. Instead of the flushing valve S13, the flushing valve S12 is used when cleaning the powder conveyor 49. The cleaned powder can be suctioned off via the suction opening 162 and line 37.

For the reasons mentioned above, it is advantageous if a large amount of compressed air (e.g. 5 bar) is blown not only through the flushing valve S13, but also through the flushing valve S12.

As soon as the sieve 24 or the ultrasonic sieve is in the cleaning container 14, the lid 15 is closed with the help of the pneumatic cylinder 17. An air gap can remain between the lid 15 and the cleaning container 14. In another embodiment, the lid 15 can also be placed on the cleaning container 14 in an airtight manner.

Compressed air is now blown onto the sieve 24 from above and below through the nozzles 19.1 and 20.1. The resulting powder-air mixture is sucked off via the suction line 13 and can be fed to the cyclone 90 and/or the secondary filter 100.

As soon as the sieve 24 is clean, the blowing off of the sieve is stopped. If the powder container 3 and the container lid 23 are clean, blowing off is also stopped here.

If the locks 18 were previously closed, they will now be opened again. The container lid 23 is lifted and the container cleaning unit 28 is moved back into the parking position (see Figures 4 - 7 ). The lid 15 is also lifted. After the cleaning mode is completed, the sieve 23 is moved back into its working position. You can then start pumping powder again.

Cleaning company with intensive cleaning

In order to clean the powder center 1 and the other components of the system that come into contact with the coating powder even more thoroughly, the following cleaning steps can be carried out. The steps are preferably carried out automatically and coordinated by the controller 70. The powder storage container 3 and the container lid 23 are cleaned with the cleaning unit 28 as described above. In a further step, a change to a different coating powder is carried out. The other coating powder can be the powder with which the workpieces 65 are to be coated next. However, this is not absolutely necessary. Instead, you can also switch to a special cleaning agent. The cleaning agent can, for example, contain granules a grain size between 2 mm and 7 mm. The grain size, the grain material and the grain quality are preferably selected so that, on the one hand, they can be conveyed through all openings in the powder system and, on the other hand, they have a good cleaning effect. When selecting the cleaning agent, it is advantageous to ensure that no additional wear occurs in the powder system and no chemical incompatibility with the coating powder.

In an additional step, the conveying mode is switched to for a limited period of time so that the other coating powder or cleaning agent flows through the individual components of the system. During the short conveying operation, for example, 3 kg of powder can be lost. But it is also possible to recover the material (the powder or the cleaning agent) in the cyclone 90. This means that the powder lines 91, 92, 93 and 94 can also be flushed with the new material. This is particularly advantageous if the new powder is used for recovery.

The powder storage container 3 and the container lid 23 are then cleaned again using the cleaning unit 28.

The foregoing description of the exemplary embodiments according to the present invention is for illustrative purposes only. Various changes and modifications are possible within the scope of the invention. For example, the various in the Figures 1 to 16 shown components of the conveyor device and the powder center can also be combined with one another in a manner other than that shown in the figures as long as the resulting combination falls within the scope of the appended claims.

Reference symbol list

1

Powder center

2

Frame profiles

3

Powder storage container

3.1

Locking recording

3.2

Powder outlet opening

3.3

Compressed air connection for purge air

3.4

Powder outlet

4

Powder conveyor

4.2

Powder outlet

5

Powder conveyor

6

base

7

floor plate

8th

linear actuator

8.1

drive motor

9

linear actuator

9.1

drive motor

10

Cleaning container

10.1

outlet

11

Cleaning arm for the lid

11.1

Cleaning nozzles

12

linear actuator

12.1

drive motor

13

Suction line/suction pipe

13.1

Inlet opening

13.2

Inlet opening

14

Screen cleaning container

14.1

outlet

14.2

lower container section

15

Screen cleaning device cover

16

Swivel mechanism

17

lifting cylinder

18

Locking

19

Low cleaning

19.1

Sieve cleaning nozzles

20

Low cleaning

20.1

Sieve cleaning nozzles

21

hinge

22

Support arm for the powder sieve

23

Container lid

23.1

Powder inlet

23.2

Side wall

24

Ultrasonic sieve

24.1

Ultrasonic transducer

25

container bottom

25.1

Fluidizing insert

25.2

outlet

26

Cleaning arm for the powder storage container

26.1

Cleaning nozzles

27

Screen cleaning device

28

Cleaning unit/container cleaning unit

30

Fresh powder station

31

first footprint

32

second parking space

33

suction lance

34

Side wall

35

cover

36

cover

37

suction

37.1

Suction opening

37.2

Suction opening

37.3

Suction opening

38

Linear axis for the suction lance

39

Compressed air control valve

40

Compressed air control valve

41

Adjusting knob

42

Adjusting knob

43

steering

44

linear actuator

45

Swivel mechanism for powder conveyor

45.1

poor

46

Scale

47

Scale

48

Back wall

49

Powder conveyor

49.1

powder container

49.2

Powder inlet valve

49.3

Powder outlet valve

50

camp

51

camp

52

Cleaning station

53

Cleaning station

54

Shaker

55

Shaker

56

Compressed air nozzle

57

Compressed air nozzle

60

Powder coating booth

65

workpiece

70

steering

71

Control line

80

powder spray gun

81

Powder line

90

Powder recovery

91

suction line

92

suction line

93

suction line

94

Powder line

95

suction line

96

Powder return line

97

Powder line

98

Powder line

100

Post-filter

110

Powder cardboard

111

Powder carton/powder container

120

Big Bag

121

Big Bag

123

powder pump

124

powder pump

125

powder pump

126

Powder line

127

Powder line

130

coupling

131

first group of connections

132

second group of connections

141

Residual powder line

142

Residual powder line

150

Powder intermediate container

160

Suction opening

162

Suction opening

200

Powder outlet pipe

201

Fluidizing element

202

flange

203

Powder outlet channel

210

Valve for fluidizing element

211

Material valve control port M11

212

Purge air inlet

220

Shaker

301

Intermediate container/housing

302

Upper housing part

302.1

funnel-shaped inner wall

302.2

Paragraph

302.5

Interior wall

302.7

Support

303

Middle part of the housing

304

Lower housing part

304.1

funnel-shaped inner wall

304.2

Paragraph

304.5

Interior wall

304.7

housing wall

305

Pipe

306

free space

307

Powder chamber

308

Compressed air control connection

308.1

opening

309

screw

310

Powder inlet valve

310.1

Intake valve inlet

310.2

Inlet valve outlet

311

Valve housing

312

Hose nipple

313

Compressed air valve

313.1

Compressed air control connection

314

Ground wire

314.1

Ground connection

316

Valve

320

Powder outlet valve

320.1

Inlet of the exhaust valve

320.2

Exhaust valve outlet

321

Valve housing

322

flange

323

Compressed air valve

323.1

Control connection

324

flange

325

screw

327

Vacuum valve

328

Valve

340

Pressure control valve

M11

Material valve for powder

M20

Powder inlet valve

M21

Powder outlet valve

M22

Valve

S11

Flush valve

S12

Flush valve

S13

Flush valve

G1 - G36

Exhaust valves

x

X axis

y

y axis

e.g

z-axis

Claims (16)

1. A conveying device for conveying coating powder,

   - in the case of which a powder storage container (3) is provided, which has, on the bottom, a powder outlet (25.2) and a powder outlet channel (203), wherein the powder outlet (25.2) forms the inlet for the powder outlet channel (203),

   - in the case of which the powder outlet channel (203) is connected to a first powder conveyor (49) in order to convey powder from the powder storage container (3) back to a powder container (111),

   - in the case of which the powder storage container (3) has a container base (25) and a number of further powder outlets (3.2) in the region of the container base (25),

   - in the case of which a powder conveying device (3, 23, G1) is provided to convey powder through one of the further powder outlets (3.2) from the powder storage container (3) to a powder applicator (80).
2. The conveying device according to patent claim 1, in the case of which a third powder conveyor (4) is provided to convey powder from the powder container (111) into the powder storage container (3).
3. The conveying device according to patent claim 1 or 2,
   in the case of which a valve for purging air (S12) is provided, which is connected to the powder outlet channel (203) via a purging air inlet (212) and is provided for blowing purging air into the powder outlet channel (203) and/or to the first powder conveyor (49).
4. The conveying device according to any one of patent claims 1 to 3,
   in the case of which a fluidizing element (201) is provided in the powder outlet channel (203).
5. The conveying device according to patent claim 4,
   in the case of which the fluidizing element (201) is designed in a ring-shaped manner.
6. The conveying device according to patent claim 4 or 5,
   in the case of which the fluidizing element (201) is microporous so that it is permeable for air and impermeable for powder.
7. The conveying device according to any one of patent claims 1 to 6,
   in the case of which the powder storage container (3) has a circular cross section.
8. The conveying device according to any one of patent claims 1 to 7,
   in the case of which the powder storage container (3) has a base (25), which slopes towards the middle of the powder storage container (3).
9. The conveying device according to patent claim 8, in the case of which the orifice (25.2) of the powder outlet channel (203) is located in the middle of the sloping base (25).
10. The conveying device according to any one of patent claims 1 to 9,
    in the case of which the powder outlet channel (203) runs in a funnel-shaped manner.
11. The conveying device according to any one of patent claims 1 to 10,
    in the case of which the first powder conveyor (49) has a powder container (301) comprising a powder inlet and a powder outlet, a powder inlet valve (310) and a powder outlet valve (320),

    - wherein the powder inlet is connected to the powder inlet valve (310), and the powder outlet is connected to the powder outlet valve (320), and

    - wherein negative pressure can be applied to the powder container (301).
12. The conveying device according to any one of patent claims 1 to 11,
    in the case of which the third powder conveyor (4) is constructed identically to the first powder conveyor (49).
13. The conveying device according to any one of patent claims 1 to 12,
    in the case of which a container lid (23), which can be removed at least partially, is provided on the powder storage container (3).
14. A powder center comprising a conveying device according to patent claim 13,

    - in the case of which a cleaning unit (28) for cleaning of the powder storage container (3) and the container lid (23) is provided, which can be moved out of a parking position next to the powder storage container into a cleaning position in the powder storage container by means of a manipulator (8, 9),

    - in the case of which a controller (70) is provided, by means of which the cleaning unit (28) and the manipulator (8, 9) can be controlled.
15. A method for cleaning the powder center according to patent claim 14,

    - in the case of which the residual powder located in the powder storage container (3) is conveyed out by means of the first powder conveyor (49),

    - in the case of which the powder storage container (3) and the container lid (23) are cleaned by means of the cleaning unit (28).
16. The method according to patent claim 15,
    in the case of which the powder conveyors (4) are purged with compressed air.

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