Powder spray nozzle for spraying coating powder, combination of electrode holder and powder spray nozzle, as well as spray applicator with powder spray nozzle.

Description

Technical area

[0001] The invention relates to a combination of electrode holder and powder spray nozzle as well as a spray gun with electrode holder and powder spray nozzle.

[0002] In powder coating, the workpiece to be coated is coated with a layer of powder using a powder spray applicator. The powder-coated workpiece is then heated until the powder melts and forms a continuous layer. After the layer has cooled, it forms a continuous, firmly adhering protective layer to the workpiece. A suitable powder spray applicator has a powder-carrying line that opens into a powder spray nozzle on the outlet side. The coating powder to be sprayed is sprayed through the powder spray nozzle.

[0003] Particularly when coating with metallic powders, but also with other special coating powders, sputtering can occur during the powder spraying process. Sputtering occurs when powder accumulates in the powder spray nozzle to a certain size and then breaks off as clumps. When such sputtering hits the workpiece to be coated, it causes defects on the coating surface. The surface then no longer meets quality requirements. State of the art

[0004] A spray coating device for coating powder is known from the prior art DE 299 24 481 U1. The spray coating device, also referred to as a spray gun, has a barrel, to which an electrode holder and a nozzle body are connected at the downstream end. The electrode holder has a powder channel containing a web with a high-voltage electrode. The high-voltage electrode protrudes from the downstream end of the web. The web, in turn, protrudes into the nozzle body. The coating powder flows through the barrel and the electrode holder and then above and below the web through the nozzle body to the spray nozzle opening. The nozzle body has a constant cross-section over its entire length up to the orifice.With such a combination of electrode holder and nozzle body, the flow velocity of the powder-air mixture is slowed in the powder channel of the electrode holder and nozzle body. This, in turn, can lead to unfavorable turbulence of the mixture, which can then cause powder to accumulate, for example, on edges located in the powder channel. Such edges are caused, for example, by built-in components in the powder channel.

[0005] From US Pat. No. 9,616,440 B2, an electrode holder and an adjoining spray nozzle for a powder spray gun are known. The electrode holder has a powder channel containing a web with a high-voltage electrode. The web is wedge-shaped at its upstream and downstream ends. The coating powder flows through the powder channel of the electrode holder, divides at the upstream wedge, and then flows above and below the web toward the spray nozzle. The powder channel has a constant diameter in both the electrode holder and the spray nozzle. With such a combination of electrode holder and spray nozzle, the flow velocity of the powder-air mixture increases in the powder channel of the electrode holder in the area of ​​the upstream wedge due to the reduction in the channel cross-section there.Where the electrode holder's web tapers to a wedge shape, the increased channel cross-section slows the flow velocity of the powder-air mixture. These different flow velocities can lead to unfavorable turbulence of the mixture. Description of the invention

[0006] An object of the invention is to provide a combination of electrode holder and powder spray nozzle with which an even more homogeneous powder spray cloud can be generated.

[0007] Advantageously, the powder spray cloud is also more symmetrical and stable, allowing for an even more uniform coating of the workpiece.

[0008] The particularly homogeneous distribution of powder particles in the powder spray cloud also reduces fluctuations in the powder layer thickness on the workpiece. A consistent layer thickness can help reduce powder consumption.

[0009] This advantage is particularly noticeable with special-effect paints, such as metallics. The particularly homogeneous distribution of the metallic flakes across the surface of the workpiece allows for an even more consistent color effect.

[0010] In addition, energy can be saved because less compressed air and less air overall is required.

[0011] The object is achieved by an electrode holder with a powder spray nozzle for spraying coating powder with the features specified in patent claim 1.

[0012] The electrode holder with powder spray nozzle for spraying coating powder has a nozzle powder channel and an adjoining orifice with a nozzle opening through which the powder can exit the powder spray nozzle. The nozzle powder channel and the orifice are made from a single piece. When assembled, the powder spray nozzle is connected to an electrode holder, which has an electrode holder powder channel and a retaining web arranged therein for holding a high-voltage electrode. The cross-section of the electrode holder powder channel is divided by the retaining web into circular segments, which together form a first cross-sectional area. Due to the retaining web projecting into it, the nozzle powder channel has an annular cross-section with a second cross-sectional area. The first cross-sectional area and the second cross-sectional area are the same size.

[0013] Advantageous further developments of the invention result from the features specified in the dependent patent claims.

[0014] In one embodiment of the electrode holder with a powder spray nozzle, the holding web of the electrode holder has a downstream wedge that tapers in the downstream direction. When assembled, the end of the downstream wedge defines the transition point from the circular segments to the annular cross-section.

[0015] In another embodiment of the electrode holder with powder spray nozzle according to the invention, the nozzle powder channel has a conical section in which the transition from the circular segments to the annular cross-section takes place. The conical shape of the powder channel compensates for the continuous reduction in the cross-sectional area of ​​the retaining web. As a result, the cross-sectional area available to the powder in the powder channel remains constant. This has the advantage that the powder flow is even less influenced by the retaining web.

[0016] In a further embodiment of the electrode holder with powder spray nozzle according to the invention, the nozzle powder channel has a channel section located directly in front of the nozzle opening, which is shaped to form a diffuser. This creates an even more homogeneous powder cloud.

[0017] In an additional embodiment of the electrode holder with powder spray nozzle according to the invention, the diffuser expands with an opening angle ranging from 20° to 70°. The opening angle is related to the longitudinal axis of the nozzle powder channel. This reduces the flow velocity of the powder-air mixture in the nozzle and also makes the powder-air mixture even more homogeneous. The larger the opening angle, the better the flow breaks up and the wider the flow of the powder-air mixture becomes. However, this only applies within a certain range. From an opening angle greater than 70°, the flow of the powder-air mixture does not become any wider. Whether this critical angle is actually 70° also depends on the type and nature (grain size) of the powder. For example, the critical angle may be smaller with very coarse-grained powder.In addition, an opening angle greater than 80° can result in a dead space in which powder can accumulate. This value also depends on the type and quality of the powder used. It is also advantageous if the nozzle is as short as possible, where "short" refers to the axial length of the nozzle. If the opening angle is in the range of 20° to 70°, the desired flow separation is achieved so effectively with the nozzle according to the invention that the nozzle can be particularly short.

[0018] In a further development, the powder spray nozzle according to the invention is made of an air-impermeable material.

[0019] In another refinement of the powder spray nozzle according to the invention, the nozzle powder channel has a radius in the range of 0.5 mm to 2 mm where the diffuser merges into the orifice. This has the advantage that less powder is deposited in the diffuser and the orifice.

[0020] In another development of the powder spray nozzle according to the invention, the upstream end of the nozzle opening is located near the largest diameter of the diffuser.

[0021] In another development of the powder spray nozzle according to the invention, the upstream end of the nozzle opening has an opening width in the range of 3 mm to 4 mm.

[0022] In another development of the powder spray nozzle according to the invention, the downstream end of the nozzle opening has an opening width in the range of 1 mm to 3 mm.

[0023] Placing the opening in the area of ​​the largest cross-section results in the powder cloud slowing down. The flow velocity of the powder-air mixture is therefore lowest in this area. The opening width of the upstream nozzle opening (3 - 4 mm) and the downstream nozzle opening (1 - 3 mm) are designed such that the powder distribution in the powder-air mixture is homogeneous across the entire opening width of the nozzle. Designing the opening widths in this way prevents more powder from escaping at the sides of the nozzle than in the center. The opposite effect, where more powder escapes from the center of the nozzle than from the sides, leads to a dotted powder cloud, which is also to be avoided.

[0024] Advantageously, the nozzle powder channel in the powder spray nozzle according to the invention tapers at the nozzle mouth at an angle in the range of 120° to 160°, preferably in the range of 130° to 150°, and particularly preferably at 135°. Extensive testing has shown that an angle of 135° produces an optimal powder cloud pattern. This angle also has the advantage that no powder sticks to the inner wall of the nozzle mouth, while simultaneously achieving a stable powder cloud.

[0025] In addition, the powder spray nozzle according to the invention can be designed such that, when mounted, an electrode protruding from the electrode holder ends within the powder spray nozzle. This results in the powder inside the nozzle being electrostatically charged. Such a powder spray nozzle thus follows the principle of internal charging. The arrangement of the electrode inside the powder spray nozzle leads to a particularly efficient electrostatic charging of the powder-air mixture compared to the arrangement of the electrodes outside the powder spray nozzle. However, such external charging is not excluded.

[0026] The powder spray nozzle described above comprises a downstream wedge of the electrode holder which tapers in the downstream direction in such a way that it fits into the conical section of the nozzle powder channel.

[0027] In the inventive combination of electrode holder and powder spray nozzle, the downstream wedge can be shaped such that it rests against the wall of the nozzle powder channel in the conical section of the nozzle powder channel.

[0028] In a further development of the combination of electrode holder and powder spray nozzle, the electrode holder and the powder spray nozzle are designed in such a way that the powder spray nozzle can be plugged onto the electrode holder.

[0029] In addition, a powder spray gun for coating a workpiece with coating powder is proposed, which has the combination of electrode holder and powder spray nozzle described above. Short description of the drawings

[0030] In the following, the invention is further explained with several embodiments using eleven figures. Figure 1 shows the downstream section of a possible embodiment of the powder spray applicator according to the invention in longitudinal section. Figure 2 shows a combination of electrode holder and powder spray nozzle in a three-dimensional exploded view. Figure 3 shows the combination of electrode holder and powder spray nozzle in longitudinal section in the assembled state. Figure 4 shows a possible embodiment of the powder spray nozzle according to the invention in longitudinal section. Figure 5 shows the powder spray nozzle according to the invention from the front, i.e., viewed from the downstream side. Figure 6 shows the powder spray nozzle according to the invention from the rear, i.e., viewed from the upstream side. Figure 7 shows a possible embodiment of the electrode holder in a three-dimensional view. Figure 8 shows the electrode holder from the rear, or its upstream side. Figure 9 shows the electrode holder from the front, or its downstream side.Figure 10 shows the electrode holder in longitudinal section. Figure 11 shows the electrode holder rotated 90 degrees in longitudinal section. Ways to implement the invention

[0031] Figure 1 shows a possible embodiment of the downstream section of a powder applicator 60 according to the invention in longitudinal section in the assembled state. The powder applicator 60 can be, for example, a manually operated powder spray gun or an automatic spray gun. In the following, the powder spray gun is also referred to as a spray gun or gun.

[0032] The powder applicator 60 has a powder connection on the input side (not shown in the figures) via which it can be supplied with coating powder, which will also be referred to as powder below. Furthermore, the powder applicator 60 has an electrical connection (not shown in the figures) via which a high-frequency low voltage can be fed to the powder applicator. A high-voltage generator is preferably arranged in the powder applicator, which generates a high voltage from the high-frequency low voltage. It can be provided that control and information signals from a control unit (not shown in the figures) are also fed to the powder applicator via the electrical connection. Furthermore, control and information signals can also be transmitted from the powder applicator to the control unit.

[0033] The powder applicator 60 comprises, on the downstream side, an elongated housing 41 into which an electrode holder 5 can be inserted. A powder spray nozzle 1 can, in turn, be inserted onto the electrode holder 5. The housing 41 is designed such that a sleeve-shaped union nut 40 can be pushed over the housing and screwed to it. For this purpose, the housing 41 has an external thread 41.1 at its downstream end, and the union nut 40 has a corresponding internal thread. The electrode holder 5 and the powder spray nozzle 1 are fixed by means of the union nut 40 when the union nut 40 is screwed onto the housing 41.

[0034] Towards the downstream end, the union nut 40 tapers conically. In this section, an annular web 40.1 is located inside the union nut 40, which is arranged concentrically to a longitudinal axis LA.

[0035] Furthermore, a powder channel 30 is provided in the powder applicator 60, which opens on the downstream side into a powder channel 5.1 of the electrode holder 5. The powder channel 5.1, in turn, opens into a powder channel 1.1 of the powder spray nozzle 1. The powder spray nozzle 1 is also referred to below as a spray nozzle or, in short, as a nozzle. The powder channels 30, 5.1, and 1.1 are preferably arranged concentrically to the longitudinal axis LA. A nozzle opening 1.4 is located at the downstream end of the powder channel 1.1 of the nozzle.

[0036] The powder channel 30 can have a receptacle 30.1 at its downstream end, which is designed such that the powder channel 30 can be plugged into the powder channel 5.1 of the electrode holder 5. The receptacle 30.1 can be designed, for example, as a sleeve with a depth stop on the inside of the sleeve.

[0037] As soon as the trigger of the spray gun has been pulled or the control system issues a corresponding command, a powder-air mixture flows through the powder channel 30 of the applicator, passes via the powder channel 5.1 of the electrode holder 5 into the powder channel 1.1 of the powder spray nozzle 1 and is finally sprayed as a powder cloud via the nozzle opening 1.4.

[0038] In the following, the electrode holder 5 is described using the Figures 2 , 3 and 7 to 11 further explained.

[0039] The electrode holder 5 has a holding web 5.3, which is arranged within the powder channel 5.1 and fastened to the wall of the powder channel 5.1. On its upstream side, the holding web 5.3 carries an upstream powder wedge 7 and on its downstream side it has an electrode channel 5.4. Within the electrode channel 5.4 is a high-voltage electrode 6, which is also referred to below as the electrode. The geometry of the holding web 5.3 is optimized so that the powder can flow through the powder channel 5.1 as unhindered as possible and sintering of the powder on the holding web 5.3 and the formation of powder lumps are avoided. The holding web 5.3 is designed such that the upstream powder wedge 7, or in short the wedge, can be pushed onto the holding web 5.3 and removed again. In the embodiment shown, the wedge 7 is optimized with regard to wear.

[0040] The electrode holder powder channel 5.1 has a cross-section A0 in the area upstream of the wedge 7. In Figure 3, this is indicated on the x-axis as point x0. The retaining web 5.3, together with the wedge 7, divides the cross-section of the electrode holder powder channel 5.1 into two circular segments 8.1, 8.2. The upstream end of the wedge 7 thus defines the location of the transition from the circular cross-sectional area A0 to the two circular segments 8.1 and 8.2. One part of the powder P flowing through the powder channel 5.1 thus passes through one circular segment 8.1 and the other part of the powder P passes through the other circular segment 8.2. Both circular segments 8.1 and 8.2 together have a first cross-sectional area A1. Figure 3 This is marked as position x1 for example.

[0041] The electrode holder 5 can also have an outer ring 5.10 concentric with the longitudinal axis LA. The outer ring 5.10 serves, among other things, to center the electrode holder 5 in the housing 41 and seals the interior of the spray applicator 60 downstream. For this purpose, the outer ring 5.10 has a stop, to which an elastic O-ring 47 is connected on its upstream side. The O-ring 47 and the stop form an axial seal.

[0042] The electrode holder 5 can have a shoulder 5.11 on the upstream side, which supports a contact ring 46 made of a conductive material. Metal, a conductive plastic, or rubber, for example, is suitable for this purpose. The contact ring 46 is connected to the electrode 6 via one or more series-connected electrical resistors 43. The resistors 43 and the electrode 6 are arranged in an electrode channel 5.4, which passes through the shoulder 5.11, the wall of the powder channel 5.1, and the retaining web 5.3 and ends at the downstream end of the retaining web 5.3, with the electrode 6 protruding from the electrode channel 5.4 there. A high-voltage line running inside the spray applicator is guided to a contact pin 45 at the downstream end of the gun housing 41. If the electrode holder 5 is installed in the spray applicator 60, the contact pin 45 is pressed onto the contact ring 46 of the electrode holder 5 by means of a spring 44.This ensures that the high voltage is securely applied to the contact ring 46. The orientation of the electrode holder 5 is irrelevant. Thus, the electrode holder 5 can be rotated as desired around its longitudinal axis LA, yet a secure and error-free electrical contact is still guaranteed.

[0043] When a high voltage is applied to the electrode 6, the powder P flowing past the electrode 6 becomes electrostatically charged. The high voltage applied to the electrode is typically between 20 kV and 80 kV.

[0044] On the downstream side of the electrode holder 5 there is an inner ring 5.9 running concentrically to the longitudinal axis LA. This inner ring 5.9, together with the outer ring 5.10, forms an annular groove 13. When the spray applicator 60 is assembled, the annular web 40.1 of the union nut 40 projects into the groove 13 of the electrode holder 5. The geometry of the annular web 40.1 and the groove 13 are selected such that a first air gap exists between the outer ring 5.10 and the annular web 40.1 and a second air gap between the inner ring 5.9 and the annular web 40.1. The depth of the web 40.1 and the groove 13 are also selected such that an air gap exists. This creates a labyrinth for the high voltage between the high-voltage electrode 6 and the outside of the union nut 40, thus extending the distance or air gap.

[0045] In one embodiment, the electrode holder 5, as shown in the Figures 2and 11 can be seen, on its downstream side two pins 5.7 extending parallel to the longitudinal axis LA. When assembled, the two pins 5.7 engage in the slots 1.7 of the spray nozzle 1. This ensures that the nozzle slot 1.4 of the spray nozzle 1 always has the same orientation in relation to the holding web 5.3 and the wedge 7. If the electrode holder 5 is rotated about the longitudinal axis LA, the spray nozzle 1 and the nozzle slot 1.4 also rotate, so that the orientation of the nozzle slot 1.4 relative to the wedge 7 always remains the same. This has the advantage that - regardless of the orientation of the nozzle slot 1.4 - the powder jet is of consistent quality and a reproducible powder jet is guaranteed.

[0046] In the following, the powder spray nozzle is described using the Figures 3 to 6 further explained.

[0047] The powder spray nozzle 1 according to the invention has the nozzle powder channel 1.1 and an adjoining orifice 1.3 with a nozzle opening 1.4, from which the powder P can exit the powder spray nozzle 1. The nozzle powder channel 1.1 can have a receptacle 1.8 on its upstream side. This is intended to accommodate the powder channel 5.1 of the electrode holder 5. Preferably, the receptacle 1.8 has a stop 1.81, which serves to define the insertion depth for the powder channel 5.1. The receptacle 1.8 is preferably designed such that the inside of the powder channel 5.1 - when inserted into the receptacle - forms a smooth transition with the inside of the powder channel 1.1. This is intended to ensure that the powder flowing through the powder channels 5.1 and 1.1 does not deposit at the transition point.

[0048] A conical section 1.5 adjoins the receptacle 1.8 downstream. Section 1.5 has a first diameter D1 at its upstream end and a second diameter D2 at its downstream end. A cylindrical section 1.9 with a diameter D2 adjoins the conical section 1.5 of the powder channel 1.1. At the end of the cylindrical section 1.9 of the powder channel 1.1, the powder channel widens with an opening angle α1 to a third diameter D3. This section of the powder channel 1.1 forms a diffuser 1.2. The diffuser 1.2 is in turn followed by the nozzle orifice 1.3 and finally the nozzle opening 1.4, through which the powder can exit the nozzle 1.

[0049] The nozzle powder channel 1.1 can have a radius R in the range of 0.5 mm to 2 mm where the diffuser 1.2 merges into the orifice 1.3. This has the advantage that less or even no powder deposits in the diffuser 1.2 and the orifice 1.3.

[0050] In the transition area from diffuser 1.2 to orifice 1.3, particularly high precision and a particularly precise (smooth) transition are required to ensure the particularly high homogeneity of the powder cloud. Therefore, at least the two sections of the nozzle powder channel 1.1, which form diffuser 1.2 and orifice 1.3, are manufactured from a single piece.

[0051] The nozzle 1 can, for example, be made of plastic, preferably of PTFE.

[0052] It has been recognized that powder usually accumulates in flow-free or almost flow-free areas of the powder channel. One location for such powder accumulation is, for example, behind the downstream wedge of the retaining web. If the powder flow velocity decreases there because the channel cross-section has increased, the risk of powder deposits increases significantly. This finding is taken into account in the powder spray nozzle 1 according to the invention.

[0053] When assembled, the powder spray nozzle 1 is connected to the electrode holder 5. Figure 3 illustrates this. Due to the retaining web 5.3 projecting into it, which is round in this area, the nozzle powder channel 1.1 has an annular cross-section 9 with a cross-sectional area A2, which is referred to below as the second cross-sectional area A2. Figure 3 This is indicated on the x-axis by the position x2.

[0054] In order to achieve a particularly homogeneous powder cloud, it is important that the first cross-sectional area A1 and the second cross-sectional area A2 of the powder channel are the same size. One of the reasons why this should be the case is that, as mentioned above, the powder flow is influenced as little as possible, or ideally not at all, after it has passed through the wedge 7. The cross-sectional area through which the powder passes is important. By ensuring that the cross-sectional areas A1 and A2 are the same size, the flow velocity of the powder remains constant in the section x1 to x2, even though the cross-section of the holding web 5.3 changes in this section. While it is rectangular at point x1, it is round at point x2.

[0055] The conical shape of the powder channel in section 1.5 compensates for the continuous change in the cross-sectional area of ​​the retaining bar 5.3. As a result, the cross-sectional area available to the powder in the powder channel 1.1 remains constant. This has the advantage that the powder flow is even less influenced by the retaining bar 5.3.

[0056] If the powder spray nozzle 1 is to have a conical section 1.5, it is advantageous to match the conical section 1.5 and the downstream wedge 5.2 of the retaining web 5.3. In this case, the wedge 5.2 can be Figure 11 shown. The wedge 5.2 tapers in the downstream direction at an angle a4.

[0057] The angle α3 is preferably in the range of 1° to 25°. The angle α3 is generally determined by the interplay of the diameters D1, D2, and the length L1. It is particularly advantageous to design the conical wall (area 1.5) of the powder channel 1.1 such that, in the assembled state (i.e., when the nozzle 1 is inserted into the electrode holder 5), it rests against the outer flanks of the wedge 5.2. The two angles α3 and α4 are preferably equal. This advantageously prevents a gap between the wedge 5.2 and the inner wall of the conical section 1.5 of the nozzle, thus preventing powder deposition.

[0058] Advantageously, the holding web 5.3 in the electrode holder 5 is designed and arranged such that the two circular segments 8.1 and 8.2 are of equal size.

[0059] In addition, it is advantageous if the part of the holding web 5.3 which projects into the powder spray nozzle 1 is designed and arranged such that the cross-sectional area A2 of the nozzle powder channel 1.1 forms a circular ring which is arranged concentrically to the longitudinal axis LA.

[0060] The geometric design of the powder spray nozzle 1 described above can cause the powder cloud to become faster and narrower. To make the powder cloud slower and wider, a diffuser 1.2 can be provided in the powder spray nozzle 1. The diffuser 1.2 ensures that the flow velocity of the powder-air mixture is reduced. The preferably angular transition from the cylindrical section 1.9 of the powder channel 1.1 to the diffuser 1.2 at point x3 ensures a flow separation. This spreads out and swirls the powder-air mixture. The orifice 1.3 ensures that the powder-air mixture is concentrated.

[0061] The opening angle α1 in diffuser 1.2 is advantageously in the range of 20° to 70°. In a preferred embodiment, the opening angle α1 is in the range of 50° to 70°. Optimally, the opening angle α1 is 67.5°.

[0062] The nozzle powder channel 1.1 tapers at the orifice 1.3 at an angle α2. The angle α2, also called the orifice angle, is located - as shown in Figure 4 shown - on the inside of muzzle 1.3. It is preferably between 120° and 160°. Even better, the angle α2 is in the range of 130° to 150°, and particularly preferably 135°. The closer the angle α2 is to 135°, the more optimal the powder cloud. Furthermore, this angle best prevents powder from sticking to the inside of muzzle 1.3 and simultaneously creates a stable powder cloud.

[0063] It is also advantageous if the nozzle opening 1.4 widens radially outwards. An example of this is the Figures 3 to 6 The nozzle opening 1.4 can, for example, have an opening width between 1 and 3 mm near the longitudinal axis LA, preferably 2 mm. At the upstream end 1.6, the opening width is between 3 and 4 mm, preferably 4 mm.

[0064] The nozzle slot 1.4 produces a flat spray jet. For this reason, nozzle 1 is also called a flat jet nozzle.

[0065] In a possible, particularly well-functioning embodiment of the spray nozzle 1, the opening angle α1 = 42°, the diameter D2 = 11 mm, and the diameter D3 = 13 mm. This embodiment of the spray nozzle 1 is suitable, for example, for epoxy- or polyester-containing powder with a median powder grain diameter of D50 = 35 µm. List of reference symbols

[0066] 1 Powder spray nozzle 1.1 Nozzle powder channel 1.2 Diffuser 1.3 Mouth 1.4 Nozzle opening 1.5 Conical section of the nozzle powder channel 1.6 Upstream end of the nozzle opening 1.7 Slot 1.8 Receptacle 1.8 1 Stop 1.9 Cylindrical section of the nozzle powder channel 5 Electrode holder 5.1 Powder channel in the electrode holder 5.2 Downstream wedge 5.3 Retaining web 5.4 Electrode channel 5.7 Pin 5.9 Inner ring 5.10 Outer ring 5.11 Shoulder 6 High-voltage electrode 7 Upstream wedge 8.1 Circular segment 8.2 Circular segment 9 Annular cross-sectional area 10 Cross-section of the nozzle powder channel in the diffuser 13 Groove 30 Powder channel 30.1Sleeve 40Union nut 40.1Annular web 41Housing 41.1External thread 42High voltage line 43Resistance 44Spring 45Contact pin 46Contact ring on the electrode holder 47O-ring 50Labyrinth 60Powder applicator A0Cross-sectional area A1Cross-sectional area at point x1 A2Cross-sectional area at point x2 D1Diameter D2Diameter D3Diameter LALongitudinal axis L1Length L2Length L3Length RRadius α1Opening angle α2Angle α3Angle α4Angle xx-axis x0Position x1First position x2Second position x3Third position yy-axis.

Claims

1. An electrode holder and powder spray nozzle for spraying coating powder, - which has a nozzle powder channel (1.1) and an adjoining orifice (1.3) with an orifice opening (1.4), from which the powder can escape from the nozzle (1), - wherein the nozzle powder channel (1.1) and the orifice (1.3) are made in one piece, - wherein, in the assembled state, the nozzle (1) is connected to the electrode holder (5), which has an electrode holder powder channel (5.1) and a holding web (5.3) arranged therein for holding a high voltage electrode (6), - wherein the cross section of the electrode holder powder channel (5.1) is divided by means of the holding web (5.3) into circular segments (8.1, 8.2), which together form a first cross sectional surface (A1), - wherein the nozzle powder channel (1.1), due to the holding web (5.3) protruding into it, has a ring-shaped cross section (9) with a second cross sectional surface (A2), and - wherein the first cross sectional surface (A1) and the second cross sectional surface (A2) are of equal size.

2. The electrode holder and powder spray nozzle according to claim 1, - wherein the holding web (5.3) of the electrode holder (5) has a downstream wedge (5.2), which tapers in the downstream direction, and - wherein, in the assembled state, the end of the downstream wedge (5.2) defines the location of the transition from the circular segments (8.1, 8.2) to the ring-shaped cross section (9).

3. The electrode holder and powder spray nozzle according to claim 1 or 2, in the case of which the nozzle powder channel (1.1) has a conical section (1.5), in which the transition from the circular segments (8.1, 8.2) to the ring-shaped cross section (9) takes place.

4. The electrode holder and powder spray nozzle according to any one of claims 1 to 3, in the case of which the nozzle powder channel (1.1) has a channel section, which is arranged directly in front of the orifice (1.3) and which is shaped so that it forms a diffusor (1.2).

5. The electrode holder and powder spray nozzle according to claim 4, in the case of which the diffusor (1.2) widens with an opening angle (α1), which, based on the longitudinal axis (LA) of the nozzle powder channel (1.1), lies in the range of 20° to 70°.

6. The electrode holder and powder spray nozzle according to any one of claims 1 to 5, which is made of an air-impermeable material.

7. The electrode holder and powder spray nozzle according to any one of claims 4 to 6, in the case of which the nozzle powder channel (1.1) has a radius (R) in the range of 0.5 mm to 2 mm at that point where the diffusor (1.2) transitions into the orifice (1.3).

8. The electrode holder and powder spray nozzle according to any one of claims 4 to 7, in the case of which the upstream end of the nozzle opening (1.6) lies in the range of the largest diameter (D3) of the diffusor (1.2).

9. The electrode holder and powder spray nozzle according to any one of claims 1 to 8, in the case of which the upstream end of the nozzle opening (1.6) has an opening width in the range of 3 mm to 4 mm.

10. The electrode holder and powder spray nozzle according to any one of claims 1 to 9, in the case of which the nozzle powder channel (1.1) tapers in the orifice (1.3) with an angle (α2), which lies in the range of 120° - 160°.

11. The electrode holder and powder spray nozzle according to any one of claims 1 to 10, which is formed so that, in the assembled state, an electrode (6) protruding from the electrode holder (5) ends within the powder spray nozzle (1).

12. The electrode holder and powder spray nozzle according to any one of claims 2 to 11, in the case of which the downstream wedge (5.2) of the electrode holder (5) tapers in the downstream direction in such a way that it can be accommodated in the conical section (1.5) of the nozzle powder channel (1.1).

13. The electrode holder and powder spray nozzle according to any one of claims 2 to 12, in the case of which the downstream wedge (5.2) is shaped in such a way that it rests against the wall of the nozzle powder channel (1.1) in the conical section (1.5) of the nozzle powder channel (1.1).

14. The electrode holder and powder spray nozzle according to any one of claims 2 to 13, in the case of which the electrode holder (5) and the powder spray nozzle (1) are formed in such a way that the powder spray nozzle (1) can be plugged onto the electrode holder (5).

15. A powder spray gun for coating a workpiece with coating powder, which has an electrode holder (5) and a powder spray nozzle (1) according to any one of the preceding claims.