Catching nozzle and pneumatically operated injector with catching nozzle as well as method for operating a pneumatically operated injector

Abstract

Nozzle for a pneumatically operated injector for conveying coating powder, - with an inlet (2.1) and a subsequent first channel section (2.2) for mixing coating powder with conveying air (FL), wherein the diameter (d2) of the first channel section (2.2) is constant and is a maximum of 3.5 mm, - with a second channel section (2.3) which is conical and connects downstream to the first channel section (2.2), and - with a shoulder (2.8) to specify the position of the catching nozzle (2) in the pneumatically operated injector, wherein the shoulder (2.8) has a channel for metering air (2.5).

Description

Technical field

[0001] The invention relates to a collection nozzle for a pneumatically operated injector for conveying coating powder. The invention further relates to a pneumatically operated injector for conveying coating powder with the collection nozzle according to the invention. The invention is defined in the claims.

[0002] To coat workpieces with coating powder, or simply powder, the powder is transported from a powder storage container to a powder spray gun by means of a powder conveying device and applied to the workpiece using the powder spray gun. The powder conveying device, which is also referred to as an injector in the following, conveys the powder from the powder storage container using conveying air. Inside the injector, the mixture of conveying air and powder flows through a powder channel of a collection nozzle. Metered air is added to the powder-conveying air mixture by means of the collection nozzle to achieve a defined overall airflow. Such a powder conveying device and a collection nozzle for the powder conveying device are known from the prior art DE 20 2004 019 438 U1.

[0003] Document DE 103 15 029 A1 relates to a powder injector for forming and conveying a powder-air mixture.

[0004] Document DE 20 2004 019 438 U1 relates to a device for conveying powder and a collecting nozzle that can be used in the powder conveying device.

[0005] Document DE 103 57 814A1 relates to a powder spray coating device with a gas piping system.

[0006] Document DE 297 23 226 U1 concerns a compressed air injector for the pneumatic conveying of a powder.

[0007] Document US 2 807 508 A concerns a powder coater, in particular a powder coater for introducing gaseous powders into molten metal.

[0008] Document US 3,536,514 A relates to a method for electrostatically coating conductive objects with powder.

[0009] Document US 2003 / 0232132A1 relates to a cold gas spraying process and apparatus in which powder is sprayed in a gas stream under pressure onto a workpiece at or near ambient temperature to form a coating of powder on the workpiece.

[0010] Document DE 38 86 419 T2 concerns cold gas spraying processes and devices in which powder is sprayed in a gas stream under pressure onto a workpiece at or near ambient temperature to form a coating of powder on the workpiece. Description of the invention

[0011] First, a drive nozzle for a pneumatically operated injector for conveying coating powder is specified, with which as much powder as possible can be conveyed with as little conveying air as possible.

[0012] The drive nozzle for a pneumatically operated injector for conveying coating powder has an upstream conveying air inlet and an associated downstream channel section with a conveying air outlet, wherein the diameter of the downstream channel section is a maximum of 1.4 mm.

[0013] One object of the invention is to provide a catching nozzle for a pneumatically operated injector for conveying coating powder, in which the wear caused by the powder being conveyed is as low as possible and with which an optimal conversion of kinetic energy into potential energy can be achieved, so that the powder can be transported over long distances with a powder hose with a small cross-section.

[0014] The problem is solved by a capping nozzle for a pneumatically operated injector for conveying coating powder with the features according to claim 1.

[0015] The inventive nozzle for a pneumatically operated injector for conveying coating powder has an inlet and a subsequent first channel section, which is provided for mixing coating powder with conveying air, wherein the diameter of the first channel section is constant and a maximum of 3.5 mm. Furthermore, the inventive nozzle has a second channel section, which is conical and connects downstream to the first channel section. A shoulder is provided to define the position of the nozzle in the pneumatically operated injector, the shoulder having a channel for metering air.

[0016] Advantageous further developments of the invention result from the features specified in the dependent patent claims.

[0017] In one embodiment of the drive nozzle according to the invention, an upstream channel section is provided, which is arranged between the conveying air inlet and the downstream channel section and whose diameter is larger than the diameter of the downstream channel section.

[0018] In a further embodiment of the drive nozzle according to the invention, the outer contour of the drive nozzle tapers towards the conveying air outlet. This reduces the flow resistance for the aspirated powder formed by the drive nozzle and increases the efficiency.

[0019] Furthermore, in the drive nozzle according to the invention, the conveying air inlet can be connected to an annular recess located on the outside of the drive nozzle. This has the advantage that when installing the drive nozzle in the injector, the position of the conveying air inlet does not need to be taken into account, because it can always be supplied with conveying air via the annular recess.

[0020] In one embodiment of the trap nozzle according to the invention, the length of the first channel section is between 10 and 14 mm.

[0021] In another embodiment of the nozzle according to the invention, the inlet has a radius between 0.5 and 2.0 mm.

[0022] Furthermore, it is advantageous if the catching nozzle according to the invention has a first cylindrical guide surface and a second cylindrical guide surface spaced apart from it, and if the shoulder has a conically shaped side. The guide surfaces and the conically shaped side are provided to define the position of the catching nozzle in the injector. The shoulder can be clamped in the injector housing.

[0023] Advantageously, the shoulder of the catching nozzle according to the invention has a further conically shaped side. This allows the catching nozzle to be precisely centered in the injector.

[0024] Furthermore, a pneumatically operated injector for conveying coating powder can be provided, which has an embodiment of the above-mentioned drive nozzle and an embodiment of the above-mentioned capture nozzle, wherein the distance between the conveying air outlet of the drive nozzle and the upstream beginning of the mixing tube of the capture nozzle is a maximum of 4 mm.

[0025] Furthermore, a method for operating the aforementioned injector is described, in which the injector is operated with a conveying air flow and a metering air flow, wherein the sum of the conveying air flow and the metering air flow is between 1.0 and 4.0 m 3 / h lies.

[0026] In the inventive method for operating the injector, it can also be provided that the conveying airflow is between 0.7 and 4.0 m³ / h. 3 / h lies.

[0027] Finally, in the inventive method for operating the injector, it can also be provided that the injector is operated with an air pressure between 2000 and 7000 hPa. Brief description of the drawings

[0028] The invention will now be further explained with several exemplary embodiments using four figures. Fig. Figure 1 shows a cross-sectional embodiment of the injector according to the invention for conveying coating powder. Fig. Figure 2 shows the injector according to the invention in a three-dimensional view. Fig. Figure 3 shows a drive nozzle in cross-section. Fig. Figures 4a to 4g show an embodiment of the capture nozzle according to the invention in top view, side view, cross-section and three-dimensional views. Ways to implement the invention

[0029] Fig. Figure 1 shows a possible embodiment of the powder conveying device according to the invention in cross-section. The longitudinal axis of the injector is labelled LA. Conveying air FL is directed through a conveying air channel 7 to a drive nozzle 1 via a conveying air connection 5, which is connected to the housing 4 of the injector via a screw connection 6.

[0030] In addition to the conveying air connection 5, the injector has a metering air connection 8, which is screwed to the housing 4 via a screw connection 9 and has a metering air channel 10. Metering air DL is directed via the metering air channel 10 into a further metering air channel 14, which is formed by the outer surface of a collecting nozzle 2 and the housing 4.

[0031] The distance l1 between the conveying air outlet of the drive nozzle 1 and the beginning of the mixing tube 2.2 of the collecting nozzle 2 is a maximum of 4.0 mm and preferably 3.0 mm.

[0032] An intake pipe can be attached to the intake manifold 15, which is then connected to Fig. 1 is not shown. To seal the intake pipe in the area of ​​the intake manifold 15, two seals 19.1 and 19.2 are provided on the intake manifold 15.

[0033] In Fig. 2 is the embodiment of the injector according to Fig. 1 shown in a three-dimensional view.

[0034] The propulsion nozzle 1 is in Fig. Figure 3 shows an enlarged cross-sectional view. The drive nozzle 1 has a conveying air inlet 11.1, to which an upstream channel section 11.2, a middle channel section 11.3, and a downstream channel section 11.4 are successively connected. At the end of the downstream channel section 11.4 is the conveying air outlet, which is also referred to as the drive nozzle outlet. The conveying air FL thus flows from the conveying air channel 7 through the conveying air inlet 11.1, the upstream channel section 11.2, the middle channel section 11.3, and the downstream channel section 11.4, and then flows out of the drive nozzle outlet towards the receiving nozzle 2. As the conveying air FL flows towards the receiving nozzle 2, it picks up powder P via the injector's intake channel 3. This causes powder P to be drawn in through the intake channel 3, which is located in the intake pipe 15 of the injector.

[0035] To seal the conveying air channel 7, 11.1, 11.2, 11.3, 11.4 to the outside, a sealing ring 18.1 is provided between the drive nozzle 1 and the housing 4. To ensure that the conveying air FL flows exclusively through the conveying air channel 7, 11.1, 11.2, 11.3, 11.4 into the intake channel 3 of the injector, a further sealing ring 18.2 is provided between the drive nozzle 1 and the housing 4.

[0036] In the drive nozzle 1, for example, the upstream channel section 11.2 has a constant diameter d0 and the downstream channel section 11.4 has a constant diameter d1.

[0037] The upstream channel section 11.2 has a diameter d0 in the range of 1.5 mm to 3.0 mm. The downstream channel section 11.4 of the drive nozzle 1 has a diameter d1 that is less than or equal to 1.4 mm.

[0038] Preferably, the diameter d1 is 1.2 mm. The central channel section 11.3, which connects the upstream channel section 11.2 with the downstream channel section 11.4, is conically shaped. The drive nozzle 1 can be manufactured as a turned part. To produce the conveying air channel 11.2, 11.3, 11.4, a suitably shaped hole is drilled into the drive nozzle 1. Subsequently, the bore is hermetically sealed on one side by means of a plug 17.

[0039] Furthermore, the drive nozzle 1 has an annular recess 11.5 on its outer surface, through which the conveying air channel 7 is connected to the conveying air inlet 11.1. This has the advantage that when installing the drive nozzle 1 in the injector, the position of the conveying air inlet 11.1 does not need to be taken into account, because it can always be supplied with conveying air FL via the annular recess 11.5.

[0040] As in the Fig. As can be seen in Figures 4a to 4g, the collecting nozzle 2 has a shoulder 2.8 with a first conical side 2.6 and a second conical side 2.7. The shoulder 2.8 contains two recesses 2.5, which serve as additional metering air channels. The metering air DL flows through metering air channel 10 and through the additional metering air channel 14, as well as through the two metering air channels 2.5, to an annular channel 21, through which it is evenly distributed along the outer surface of the collecting nozzle 2. The annular channel 21 is formed by the outer surface of the collecting nozzle 2 and the inner side of the guide sleeve 12. The metering air DL then flows through a gap located between the outer surface of the collecting nozzle 2 and the inner side of the guide sleeve 12 into a powder hose 20, where it is mixed with the mixture of powder P and conveying air FL.

[0041] Furthermore, the catching nozzle 2 has a first cylindrical guide surface 2.10 and a second cylindrical guide surface 2.11 spaced apart from it. The two guide surfaces 2.10 and 2.11 and the conical side 2.6 are designed to define the position of the catching nozzle 2 in the injector.

[0042] Fig. Figure 4a shows the nozzle 2 according to the invention in a top view. Fig. Figure 4b shows the capture nozzle 2 in a three-dimensional view and Fig. 4c the catching nozzle 2 in side view. In Fig. 4d is the capture nozzle 2 compared to the illustration from Fig. 4c shown rotated by 90°. Fig. 4e and Fig. Figures 4f show the capture nozzle 2 again from different angles in a three-dimensional view. Fig.Figure 4g shows a cross-sectional view of the collecting nozzle 2. The collecting nozzle 2 has an opening 2.1 with a radius R. The area of ​​the opening 2.1 thus extends from the upstream end face of the collecting nozzle 2 downstream within the collecting nozzle to the end of the bend with radius R. Immediately following the opening 2.1 is an upstream channel section 2.2, which is also referred to as a mixing tube. This is followed by a conical channel section 2.3, which is designed as a diffuser. The outlet of the diffuser is marked with reference numeral 2.4. The radius R in the opening area 2.1 is between 0.5 and 2.0 mm. The radius R influences the powder throughput. The length l2 of the mixing tube 2.2 is between 10 and 14 mm. Preferably, it is 12 mm. The length l2 of the mixing tube 2.2 is therefore the length of the section in which the diameter d2 is constant. The diameter d2 of the mixing tube 2.2 is less than or equal to 3.5 mm.

[0043] To seal the metering air duct 10, 14 upstream of the intake duct 3, a seal 16 is located at the upstream end of the catching nozzle 2.

[0044] The catching nozzle 2 is partially located in the housing 4 of the injector and is clamped to the housing 4 of the injector via a guide sleeve 12 and a union nut 13.

[0045] The union nut 13 has a thread 13.1 on its inside, via which it can be screwed onto the housing 4 of the injector.

[0046] The guide sleeve 12 can consist of an electrically non-conductive material on the inside and be surrounded on the outside by a layer of electrically conductive material or an electrically conductive sleeve. The electrical and mechanical properties of such an electrically conductive sleeve are described in German utility model DE 202 04 116 U1. Alternatively, the entire guide sleeve 12 can also be made of an electrically conductive material.

[0047] The guide sleeve 12 can be electrically attached to the grounded housing 4 of the injector by means of the union nut 13, which is also electrically conductive. This dissipates any electrical charge that arises from friction between the powder and the hose.

[0048] The guide sleeve 12 has two ribs 12.1 and 12.2 at its downstream end, which serve to secure the powder conveying hose 20. It is designed that the guide sleeve 12 and the union nut 13 remain attached to the hose 20 during disassembly. Thus, if the hose 20 is separated from the injector housing 4 using the union nut 13, the union nut 13 and the guide sleeve 12 remain attached to the hose 20, while the catching nozzle 2 remains in the injector housing 4.

[0049] In the assembled state, the union nut 13 presses the conical surface 12.3 of the guide sleeve 12 onto the similarly conical side 2.7 of the catching nozzle 2. This presses the second conical side 2.6 of the catching nozzle 2 onto a conical stop 4.1, which is located in the injector housing 4 at the downstream end.

[0050] With the aid of the injector according to the invention, powder can be conveyed via a powder hose 20 with an inner diameter of 7 to 12 mm over distances of up to 30 m to the powder spray gun. Reference symbol list 1 propulsion nozzle 2 Catching nozzle 2.1 Mouth / Inlet 2.2 Mixing tube 2.3 Diffuser 2.4 Outlet 2.5 Metering air duct 2.6 First outer cone 2.7 second outer cone 2.8 Shoulder 2.9 Ring groove 2.10 first cylindrical guide 2.11 second cylindrical guide 3 Intake channel 4 injector housings 4.1 Inner cone 5 Conveying air connection 6 screw connection 7 Conveyor air duct 8 Metering air connection 9 screw connection 10 Metering air duct 11.1 Conveying air inlet 11.2 upstream canal section 11.3 middle canal section 11.4 downstream canal section 11.5 ring-shaped recess 12 Guide sleeve 12.1, 12.2 ribs 12.3 Inner cone 13 Union nut 13.1 Thread 14 Metering air duct 15 intake manifolds 16 sealing ring 17 grafts 18.1, 18.2 Seals 19.1, 19.2 Seals 20 hoses 21 Ring channel DL metering air FL Conveying air P coating powder LA Longitudinal axis R radius l1 distance l2 length d0 diameter d1 diameter d2 diameter

Claims

[1] Nozzle for a pneumatically operated injector for conveying coating powder, - with an inlet (2.1) and a subsequent first channel section (2.2) for mixing coating powder with conveying air (FL), wherein the diameter (d2) of the first channel section (2.2) is constant and is a maximum of 3.5 mm, - with a second channel section (2.3) that is conical and connects downstream to the first channel section (2.2), and - with a shoulder (2.8) to specify the position of the catching nozzle (2) in the pneumatically operated injector, wherein the shoulder (2.8) has a channel for metering air (2.5). [2] A collection nozzle according to claim 1, wherein the length of the first channel section (2.2) is between 10 and 14 mm. [3] A catching nozzle according to claim 1 or 2, wherein the inlet (2.1) has a radius between 0.5 and 2.0 mm. [4] Nozzle according to one of claims 1 to 3, - with a first cylindrical guide surface (2.10) and a second cylindrical guide surface (2.11) spaced apart from it, - wherein the shoulder (2.8) has a conically shaped side (2.6), - wherein the guide surfaces (2.10, 2.11) and the side (2.6) are provided to specify the position of the catching nozzle (2) in the pneumatically operated injector, and - wherein the shoulder (2.8) can be clamped in the pneumatically operated injector. [5] A catching nozzle according to claim 4, wherein the shoulder (2.8) has a further conically shaped side (2.7). [6] Pneumatically operated injector for conveying coating powder with a collecting nozzle according to one of claims 1 to 5, - with a drive nozzle (1) having an upstream conveying air inlet (11.1) and an associated downstream channel section (11.4) with a conveying air outlet, wherein the diameter of the downstream channel section (11.4) is a maximum of 1.4 mm, and - wherein the distance (l1) between the conveying air outlet of the drive nozzle (1) and the beginning of the first channel section (2.2) of the capture nozzle (2) is a maximum of 4.0 mm. [7] Method for operating a pneumatically operated injector according to claim 6, wherein the pneumatically operated injector is operated with a conveying air flow (FL) and a metering air flow (DL), wherein the sum of conveying air flow (FL) and metering air flow (DL) is between 1.0 and 4.0 m 3 / h lies. [8] Method according to claim 7 for operating a pneumatically operated injector according to claim 6, wherein the conveying airflow (FL) is between 0.7 and 4.0 m 3 / h lies. [9] Method according to claim 7 or 8 for operating a pneumatically operated injector according to claim 6, wherein the pneumatically operated injector is operated with an air pressure between 2000 and 7000 hPa.

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