EP2650052B2 - Powder beaker spray gun and spray coating device with same - Google Patents

Description

Technical area

The invention relates to a powder cup spray gun and a spray coating device with a powder cup spray gun which are suitable for spraying coating powder.

For the powder coating of individual parts and small quantities as well as for laboratory and development purposes, it makes sense to use handy, flexible and yet powerful equipment. The industry has developed powder cup guns for these applications. In contrast to the powder spray guns used for series and contract coating, the powder reservoir of these powder cup spray guns is located directly on the spray gun. The powder storage container, which is also referred to below as a powder cup or, for short, a cup, has a relatively small capacity. When processing small and medium quantities of powder, the user can save powder because the powder does not have to be transported to the spray gun via a powder hose from a large, remote powder storage container. In addition, the user does not have to clean the powder hose when changing the color. And cleaning the small powder cup is much less time-consuming than cleaning the large storage container.

State of the art

From the state of the art DE 25 14 160 A an electrostatic sprayer for powdery spray is known. The gun-shaped sprayer has a powder container that can be screwed onto the top of the gun head. For this purpose, the gun head has a countersink at the top with an internal thread. The powder container comprises a connection piece with an external thread that matches the internal thread. In the connection piece there is also an air inlet hole for loosening gas. The screw connection forms a seal so that the loosening gas cannot escape.

From the pamphlet JP 6 320101 A a powder spray gun for casting dishes is known. The powder made of plastic is injected into a recess in a heated mold. The powder is in a powder container at the back of the spray gun.

From the operating instructions "Tribo cup gun PEM-TG3" status 04/2006, no. 0351716, which is published on the Internet as state of the art and is sold by Wagner GmbH under item no. 0351036, a cup gun for the above Uses known. Figure 1 is taken from the operating instructions and shows the cup gun D in a three-dimensional view. The cup gun D is a manually operated powder spray gun with a powder storage cup H, which is screwed onto the gun D from above in the rear area. The cup gun D has a screw thread J for this purpose.

A similar cup gun working with triboelectric charging is known from the service instructions "Manual and Automatic Guns", June 2006 edition, No. 0351883, page 121 ff, which is also published on the Internet as prior art.

Finally, from the operating instructions "Powder Cup Gun PEM-CG4-HiCoat" Edition 02/2007 No. 0390821, a powder cup gun operating with corona charging (high voltage) is known.

These cup guns have in common that they have an electrical connection G and a supply connection F for compressed air at the lower end of the handle. The electrical connection G is connected to a control unit via an electrical cable and the supply connection F via a compressed air hose. The compressed air supply to the cup gun can be adjusted with the help of the control unit. However, these cup guns have the disadvantage that the color change cannot be carried out quickly enough. The user must first carefully unscrew the supply cup from the gun. To do this, he holds the pistol with one hand and grabs the cup with the other hand and begins to unscrew it. As a rule, he will grip the cup several times in order to be able to unscrew it completely. However, reaching around is tricky, especially when there is still powder in the storage cup, because there is then the risk of the powder spilling or trickling out of the outlet opening of the powder cup.

With the powder cup guns described above, the compressed air supplied to the gun via the supply connection is divided into conveying air, tribo air (with the tribo guns) or atomizing air (with the corona gun), metering air and air for fluidizing the powder. For this purpose there is a manually adjustable valve for the conveying air, a manually adjustable valve for the metering air, a manually adjustable valve for the atomizing air or tribo air and a manually adjustable valve for the fluidizing air at the rear of the powder cup gun. All valves are connected on the inlet side to the supply connection. If a valve is now adjusted, it cannot be ensured that this has no effect on the other air flows. The user does not know how high the four air pressures actually are. The four valve settings provide only very imprecise information about this. This in turn leads to the fact that it is not easy to make recommendations as to how the individual air pressures are to be set for other powder spray guns, especially those used in series production. The results achieved are therefore only reproducible to a limited extent and the compressed air settings cannot be easily transferred to other spray guns. However, this is among other things in the development of coating powder is desirable.

Presentation of the invention

An object of the invention is to provide a powder cup spray gun in which the color change can be carried out quickly and smoothly.

The object is achieved by a powder cup spray gun with the features specified in claim 1.

The powder cup spray gun according to the invention has an injector with a powder inlet, a powder cup and a receptacle for the powder cup. The powder inlet of the injector is connected to the receptacle. The powder cup and the receptacle are designed such that the powder cup can be plugged into the receptacle. In addition, a handle with a connection for conveying air, a connection for atomizing air and a connection for metering air is provided. The connection for the conveying air and the connection for the metering air are connected to the injector via lines running in the handle.

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

For example, in the powder cup spray gun according to the invention, a gun housing can be provided which is designed in such a way that the injector can be screwed on from the outside. In this way, the injector is quickly and easily accessible and can be unscrewed in a few simple steps. The staff can then service and clean the injector.

In one embodiment of the powder cup spray gun according to the invention, a sealing ring is provided in the receptacle for the powder cup. A secure and reliably sealing connection between the receptacle and the powder cup is thus achieved.

In a further embodiment of the powder cup spray gun according to the invention, a further sealing ring is provided in the receptacle for the powder cup. This seals the connection between the receptacle and the powder cup even more securely and reliably.

In another embodiment of the powder cup spray gun according to the invention, a powder line and a metering air channel are provided, the metering air channel opening into the powder line in a ring shape.

The injector of the powder cup spray gun according to the invention can have a driving nozzle and a catching nozzle, the driving nozzle having a driving nozzle channel and the catching nozzle having a mixing tube section. The ratio between the diameter of the driving nozzle channel and the inner diameter of the mixing tube section is preferably in the range between 1.9 and 2.5.

The powder cup used for the powder cup spray gun described above can have a side wall that is funnel-shaped. In addition, a powder outlet which is tubular in shape can be provided in the powder cup. This ensures that the powder is continuously sucked into the injector without additional measures. Fluidization with fluidizing air is no longer necessary.

In another embodiment, the powder cup has a lid with a separable cover cap. The cover cap is designed in such a way that it is suitable for closing the powder outlet.

In addition, a spray coating device with the above-described powder cup spray gun and a control unit is proposed. The control unit is designed and operated in such a way that it can be used to regulate the conveying air, the atomizing air and the metering air. In addition, compressed air hoses are provided with which the control unit is connected to the connection for the conveying air, the connection for the metering air and the connection for the atomizing air of the powder cup spray gun. The powder cup spray gun according to the invention in connection with the control device advantageously achieves an extraordinarily high and permanently constant quality of the powder spray jet.

Brief description of the drawings

Figur 1

zeigt eine Pulverbechersprühpistole gemäss dem Stand der Technik in einer dreidimensionalen Ansicht.

Figur 2

zeigt eine mögliche Ausführungsform der erfindungsgemässen Pulverbechersprühpistole in einer dreidimensionalen Ansicht.

Figur 3

zeigt den unteren Teil des Griffs der erfindungsgemässen Pulverbechersprühpistole in einer dreidimensionalen Ansicht.

Figur 4

zeigt die erfindungsgemässe Pulverbechersprühpistole im teilweise zerlegten Zustand in einer dreidimensionalen Ansicht.

Figur 5

zeigt eine mögliche Ausführungsform eines Steuergeräts für die erfindungsgemässe Pulverbechersprühpistole.

Figur 6

zeigt die erfindungsgemässe Pulverbechersprühpistole im teilweise zerlegten Zustand in einer dreidimensionalen Ansicht.

Figur 7

zeigt die erfindungsgemässe Pulverbechersprühpistole im Längsschnitt.

Figur 8

zeigt unter anderem jene Druckluftleitungen und Anschlüsse, die im Griff der Sprühpistole untergebracht sind.

Figur 9

zeigt den hinteren Teil der erfindungsgemässen Pulverbechersprühpistole im Längsschnitt in einer vergrösserten Ansicht.

In the following, the invention is explained further with several exemplary embodiments with reference to 9 figures.

Figure 1

shows a powder cup spray gun according to the prior art in a three-dimensional view.

Figure 2

shows a possible embodiment of the powder cup spray gun according to the invention in a three-dimensional view.

Figure 3

shows the lower part of the handle of the powder cup spray gun according to the invention in a three-dimensional view.

Figure 4

shows the powder cup spray gun according to the invention in a partially disassembled state in a three-dimensional view.

Figure 5

shows a possible embodiment of a control device for the powder cup spray gun according to the invention.

Figure 6

shows the powder cup spray gun according to the invention in a partially disassembled state in a three-dimensional view.

Figure 7

shows the powder cup spray gun according to the invention in longitudinal section.

Figure 8

shows, among other things, the compressed air lines and connections that are housed in the handle of the spray gun.

Figure 9

shows the rear part of the powder cup spray gun according to the invention in a longitudinal section in an enlarged view.

Ways of Carrying Out the Invention

In Figure 2 a possible embodiment of the powder cup spray gun according to the invention is shown in a three-dimensional view. The powder cup spray gun is also referred to below as a cup spray gun or, for short, a spray gun. The cup spray gun has a housing 1. At its rear end 1.2 there is a pneumatically operated powder injector 2, which in the following is also referred to as an injector for the sake of simplicity. The cup spray gun also has a handle 1.1 with which the operating personnel can hold and operate the spray gun. In the embodiment shown here, the handle 1.1 is part of the housing 1, but this does not have to be mandatory. The handle 1.1 can also be a separate component. The operating personnel can control the powder flow and, if necessary, also the high voltage, via a trigger 10 which is built into the handle 1.1. If the trigger 10 is operated, the high voltage is applied to a high voltage electrode 12.1 (see Figure 4 ) at. The coating powder, or powder for short, flowing past the high-voltage electrode 12.1 is charged electrostatically and sprayed through a powder jet nozzle 9.

At the lower end of the handle 10 there are several connections 5, 6, 7 and 11. Figure 3 shows this part of the handle in a three-dimensional view. The injector 2 is supplied with conveying air via a connection 5 for conveying air, which is also referred to as conveying air connection. The injector 2 is supplied with metering air via a connection 6 for metering air, also called metering air connection. In addition, at the lower end of the handle 10 there is also a connection 7 for atomizing air, which is also referred to as the atomizing air connection. The atomizing air is fed into the spray gun up to its mouth. With the help of the atomizing air, the operating personnel can adjust the shape of the powder cloud. In addition, the atomizing air can be used to cool the high-voltage cascade and to remove the ozone generated. The atomizing air can also protect the electrode 12.1 from powder deposits. The atomizing air also prevents powder from getting into the opening of the electrode holder 12 from which the electrode 12.1 protrudes. If not the in Figure 2 The flat jet nozzle shown is used, but a round jet nozzle with a baffle plate arranged in front of it, the atomizing air can also protect the baffle plate from powder deposits. Finally, there is also an electrical connection 11 at the lower end of the handle 10, via which a high-frequency low voltage is fed to the pistol. In the spray gun there is a high-voltage generator, which comprises a transformer and a downstream high-voltage cascade, and which transforms the high-frequency low voltage into a high voltage. Control and information signals from an in Figure 5 control unit 30 shown are guided to the spray gun. In addition, control and information signals can also be passed from the spray gun to control device 30. As soon as the trigger 10 has been actuated, the coating powder is sprayed via the spray nozzle 9.

At the rear of the spray gun there can be a control panel 27 with buttons, via which, for example, a recipe can be selected from a list of several recipes stored in the control device 30. The control device 30 then regulates the individual parameters, such as metering air, conveying air, atomizing air and voltage accordingly. However, the recipes or airs can also be selected directly on the control device 30. A flushing recipe can also be selected for thorough cleaning of the powder channels inside the gun.

The powder to be sprayed is in a powder cup 3, which is in the in Figure 2 embodiment shown sits at the rear end of the spray gun. The powder cup 3 has a removable lid 4 with a closable air inlet opening 4.3 (see Figure 7 ). During the coating operation, the air inlet opening 4.3 is usually open, so that no negative pressure arises in the powder cup 3. If necessary, for example when the spray gun is not in operation, or when the powder cup 3 is not placed on the spray gun, the air inlet opening 4.3 can be closed with a closure 4.2. To do this, press the nipple of the closure 4.2 into the air inlet opening 4.3. The cover 4 also has a cover cap 4.1, which can be removed and serves to open the powder outlet opening 3.1 ( Figure 6 ) of the powder cup 3 at the bottom. If you want to fill the powder cup 3 with coating powder, you can detach the cover cap 4.1 from the cover 4 and use it to close the powder outlet opening 3.1 at the lower end of the powder cup 3. The powder cup 3 can then be filled and, if desired, the top of the powder cup can be closed with the lid 4. In this way it is ensured that the powder located in the powder cup 3 cannot escape. If you now want to put the powder cup 3 on the spray gun, turn the powder cup 3 with the powder outlet opening 3.1 upwards and remove the cover cap 4.1. Then the powder outlet opening 3.1 is inserted into the intended receptacle 2.1 in the injector 2. Through the two O-rings 16 and 17 (see Figure 9 ) a secure and reliably sealing connection between the receptacle 2.1 and the powder outlet opening 3.1 of the powder cup 3 is achieved. The coating powder now enters the powder outlet opening 3.1 The inlet 2.2 of the injector 2 immediately following it. The inlet 2.2 is also referred to as the intake duct. The coating powder thus reaches the injector 2 by the shortest route from the powder cup 3 and from there via the powder line 15 located inside the spray gun to the powder spray nozzle 9.

The injector 2 works according to the Venturi principle. With the aid of a continuous flow of conveying air, a negative pressure is generated in the injector, which causes powder to be sucked in from the powder cup 3 and transported together with the flow of conveying air in the direction of the powder spray nozzle 9. In addition, metering air is fed to the injector 2 in order to support the conveyance of the powder to the spray nozzle 9. For this purpose, the injector 2 comprises a propulsion nozzle 13 (see Figures 6 and 7th ), which via a compressed air line 19 with conveying air ( Figure 8 ) can be supplied. The conveying air flowing out of the driving nozzle 13 generates a negative pressure in the suction channel 2.2 so that the powder is sucked out of the powder cup 3. Downstream, behind the propellant nozzle 13, there is a collecting nozzle 14 which opens into the powder line 15.

In the injector 2 there is also a compressed air channel which opens into the powder line 15. The metering air can be fed into the powder line 15 via the compressed air channel. The compressed air channel advantageously opens into the powder line in a ring shape. The amount of metering air to be fed in depends on the total amount of air required. The sum of metering air and conveying air is referred to here as the total amount of air.

Figure 4 shows the powder cup spray gun according to the invention in a partially disassembled state in a three-dimensional view. In order to be able to clean and maintain the front, that is to say downstream, part of the powder cup gun, a union nut 8 that can be unscrewed by hand is first removed. The spray nozzle 9 and the electrode holder 12 with the high-voltage electrode 12.1 can then be removed.

Figure 5 shows a possible embodiment of a control device 30 for the powder cup spray gun according to the invention. In this embodiment, the control device 30, which is also referred to as a control unit, has a first adjusting knob 31, via which the conveying air quantity per unit of time can be set. In addition, a second adjusting knob 32 is provided, via which the amount of metered air per unit of time can be set. Finally, a third adjusting knob 33 is also provided, by means of which the amount of atomizing air per unit of time can be adjusted. The control unit 30 comprises corresponding control loops which ensure that the set target values for the conveying air, metering air and atomizing air are actually adhered to. The actual values of the conveying air, metering air and atomizing air can be read on the associated displays 34, 35 and 36.

Figure 6 shows the powder cup spray gun according to the invention in a partially disassembled state in a three-dimensional view. With the aid of the two screws 28, the injector 2 can be detached from the flange 26 quickly and easily in a few simple steps. The driving nozzle 13 and the collecting nozzle 14 can now be pulled out and checked, cleaned or replaced if necessary. In addition, a short connecting pipe 37 is provided which connects the conveying air line arranged in the gun to the injector 2 and which can also be removed. The O-rings 38 and 39 serve as seals.

Figure 7 shows the powder cup spray gun according to the invention in longitudinal section.

In Figure 8 the compressed air lines and connections that are housed in handle 1.1 of the spray gun are shown, among other things.

The conveying air connection 5 is connected to one end of the compressed air line 19 via a connection nipple 21. Another connection nipple 23 connects the other end of the compressed air line 19 to a conveying air duct in the flange 26, which in turn is connected to the conveying air duct of the injector 2.

The metering air connection 6 is connected to one end of the compressed air line 18 via a connection nipple 22. Another connection nipple 24 connects the other end of the compressed air line 18 to a metering air channel in the flange 26, which in turn is connected to the metering air channel of the injector 2.

In addition, there is a cascade plug 25 in the spray gun, which is connected to the cables coming from the electrical connection 11. The plug contacts of the high-voltage cascade are plugged into the cascade plug 25. The cascade connector 25 also serves to hold the compressed air line 20 (= atomizing air line) in the correct position. The downstream end of the atomizing air line 20 is placed on a connection nipple 29. This is also attached to the cascade plug 25. From there, the atomizing air flows past the high-voltage cascade. Then it is passed through the electrode holder and brought to the mouth of the spray gun.

Figure 9 shows the rear part of the powder cup spray gun according to the invention in a longitudinal section in an enlarged view. The collecting nozzle 14 has a downstream section downstream behind the O-ring. This downstream section and the channel surrounding it in the flange 26 and the powder line 15 surrounding it form a metering air channel 40. The metering air channel 40 is designed such that it opens into the powder line 15 in an annular manner. The powder line 15 is also referred to as a powder tube.

The following dimensions for the injector 2 have proven to be particularly advantageous in the powder cup gun.

Driving nozzle channel diameter d1 = 1.5 mm
Diameter of the inlet opening of the collecting nozzle d2 = 3.3 mm.
The diameter of the inlet opening is d2 at the same time the inside diameter of the mixing tube.
Diameter of the outlet opening of the collecting nozzle d3 = 5.05 mm
Distance between driving nozzle and collecting nozzle I1 = 2.5 mm
Distance between the opening of the collecting nozzle and the start of the diffuser I2 = 6 mm. The distance I2 is also the length of the mixing tube.
Distance between the start of the diffuser and the end of the collecting nozzle I3 = 25 mm
Distance between the driving nozzle and the beginning of the catching nozzle D = 1.5 mm
Distance between the start of the catch nozzle and the end of the catch nozzle E = 32 mm

hat sich als besonders vorteilhaft in Bezug auf die Förderleistung herausgestellt.A ratio of the diameters d2 to d1 of $$1.9\le \frac{\mathrm{d}2}{\mathrm{d}1}\le 2.5$$

has proven to be particularly advantageous in terms of delivery rate.

The preceding description of the exemplary embodiments according to the present invention serves only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents. For example, not all of them are in the Figures 2 to 9 Components shown are required to implement the powder cup spray gun.

In an alternative embodiment it is provided that the powder cup 3 has a radially protruding nose in the region of the pipe section 3.1 and the receptacle 2.1 has one or more radial bulges. The bulges are used to accommodate the nose. The nose and bulges form a kind of bayonet lock. After the powder cup 3 has been inserted into the receptacle 2.1, it is rotated through a certain angle. In this way, the powder cup 3 is fixed even more securely on the spray gun.

List of reference symbols

1

Gun body

1.1

Handle

1.2

rear end of the powder cup gun

2

Injector

2.1

admission

2.2

Powder inlet

3

Powder cup

3.1

Pipe section

3.2

Cup wall

4th

cover

4.1

Cover cap

4.2

Clasp

4.3

Air inlet opening

5

Connection for conveying air

6th

Connection for metering air

7th

Connection for atomizing air

8th

Union nut

9

Powder jet nozzle

10

Deduction

11

Electrical connection

12

Electrode holder

12.1

electrode

13

Motive nozzle

13.1

Driving nozzle channel

14th

Collecting nozzle

15th

Powder tube

16

O-ring

17th

O-ring

18th

Air line for metering air

19th

Air line for conveying air

20th

Air line for atomizing air

21st

Hose nipple

22nd

Hose nipple

23

Hose nipple

24

Hose nipple

25th

Cascade connector

26th

flange

27

Control panel

28

screw

29

Connection nipple for the atomizing air

30th

Control unit

31

Control knob

32

Control knob

33

Control knob

34

display

35

display

36

display

37

Connecting pipe

38

O-ring

39

O-ring

40

Metering air duct

Claims (10)

1. A powder beaker spray gun,

   - on the rear end of which an injector (2) is provided comprising a powder inlet (2.2),

   - wherein a powder beaker (3) and a receptacle (2.1) for the powder beaker (3) are provided,

   - wherein the powder inlet (2.2) of the injector (2) is connected to the receptacle (2.1),

   - wherein the powder beaker (3) and the receptacle (2.1) are embodied in such a manner that the powder beaker (3) can be inserted into the receptacle (2.1),

   - wherein a grip (1.1) is provided comprising a connection for conveying air (5), a connection for atomized air (7) and a connection for metered air (6),

   - wherein the connection for the conveying air (5) and the connection for the metered air (6) are connected to the injector (2) via lines (18, 19) running in the grip (10).
2. The powder beaker spray gun according to claim 1, wherein a gun housing (1) is provided, which is embodied in such a manner that the injector (2) can be screwed on from the outside.
3. The powder beaker spray gun according to any one of claims 1 or 2,
   wherein a sealing ring (16) is provided in the receptacle (2.1) for the powder beaker (3).
4. The powder beaker spray gun according to claim 3, wherein a further sealing ring (17) is provided in the receptacle (2.1) for the powder beaker (3).
5. The powder beaker spray gun according to any one of the preceding claims,

   - wherein a powder line (15) is provided, and

   - wherein a metering air duct (40) is provided, which discharges annularly into the powder line (15) .
6. The powder beaker spray gun according to any one of the preceding claims,

   - wherein the injector (2) has a driving nozzle (13) and a collector nozzle (14),

   - wherein the driving nozzle (13) has a driving nozzle duct (13.1) and the collector nozzle (14) has a mixing tube section, and

   - wherein the ratio between the diameter of the driving nozzle duct d1 and the inner diameter of the mixing tube section d2 is in the range of between 1.9 and 2.5.
7. A powder beaker for a powder beaker spray gun according to any one of the preceding claims, wherein the side wall (3.2) is embodied in a funnel-shaped manner.
8. The powder beaker according to claim 7,
   wherein a powder outlet (3.1) is provided, which is embodied in a tubular manner.
9. The powder beaker according to claim 7 or 8,

   - wherein a lid (4) is provided comprising a separable cap (4.1),

   - wherein the cap (4.1) is embodied in such a manner that it is suitable to close the powder outlet (3.1) .
10. A spray coating device
    comprising a powder beaker spray gun according to any one of the preceding claims,

    - wherein a control unit (30) is provided, which is embodied and which can be operated in such a manner that it can control the conveying air, the atomized air and the metered air,

    - wherein compressed air tubes are provided, by means of which the control unit (30) is connected to the connection for the conveying air (5), the connection for the metered air (6) and the connection for the atomized air (7) of the powder beaker spray gun.

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