Rotary sprayer

Abstract

The present invention relates to a rotary sprayer (1) for applying a spray jet of a coating agent (e.g., paint) to a part (e.g., a motor vehicle body part). According to the invention, the design dimensions of the rotary sprayer (1) are adjusted so that the air pressure at the outlet opening of the paint nozzle (5) during operation is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the external rinse channel (20), in order to prevent the coating agent from flowing back from the outlet opening of the paint nozzle (5) in the direction of the nozzle chamber (11) due to a pressure difference. [Drawing] Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotary atomizer for applying a spray jet of a coating (eg, paint) to a part (eg, a motor vehicle body part). [Background technology]

[0002] Such rotary sprayers are well known from the prior art (e.g., US Pat. No. 5,629,399) and have a bell cup as an application element, which is attached to a bell cup shaft of the rotary sprayer that rotates during operation, and for this purpose, the bell cup shaft is usually driven by a compressed air turbine. Inside the hollow bell cup shaft, a paint tube extends through the interior of the rotary sprayer to supply the paint to be applied, and for this purpose, a paint nozzle is inserted into the end of the paint tube and ejects the paint in the direction of the bell cup. In the center of the bell cup there is a distribution disc holder, which is attached to the front surface of the bell cup.

[0003] The paint initially exits the paint nozzle in the axial direction, strikes the dispersion disc and is directed generally radially outward onto the overflow surface of the bell cup, ultimately leading to the spray edge of the bell cup from which it is sprayed.

[0004] Meanwhile, a portion of the paint that first leaves the paint nozzle passes axially through the central hole in the dispersion disk and continues to wet the front paint flow surface of the dispersion disk with paint.

[0005] Furthermore, known rotary atomizers also feature the possibility of external rinsing, rinsing the outer circumferential surface of the bell cup with a rinsing agent, for which purpose the rinsing agent can be introduced into the bell cup via the paint nozzle and then passed through an external rinsing channel into an external rinsing chamber behind the bell cup, from where it then flows over the outer circumferential surface of the bell cup. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 0715896 Summary of the Invention [Problem to be solved by the invention]

[0007] The above description explains the proper operation of a rotary sprayer in which the paint from the paint nozzle flows exclusively in a forward direction, partly through the central hole in the dispersion disk and partly radially outward on the overflow surface of the bell cup. However, in practice, it has been shown that under certain operating conditions, some of the paint from the paint nozzle can flow back into the bell cup, for example, through the external rinse channel into the external rinse chamber of the bell cup or into the nozzle chamber surrounding the paint nozzle. This paint backflow must be prevented at all costs during operation, as it can lead to contamination of the bell cup and the rotary sprayer and therefore to defective coating results.

[0008] SUMMARY OF THE INVENTION The object of the present invention is to improve upon the known rotary atomizers described above. [Means for solving the problem]

[0009] This problem is solved by a rotary atomizer according to the main claim.

[0010] The present invention is based on the fluidics discovery that unwanted backflow of paint within the bell cup is caused by improper pressure conditions within the bell cup system.

[0011] Therefore, the present invention includes the overall technical teaching of designing a rotary atomizer and a bell cup so that the air pressure at the outlet opening of the paint nozzle during operation is always lower than the air pressure in the nozzle chamber of the bell cup and in the external rinse channel, in order to avoid the annoying backflow of coating material from the outlet opening of the paint nozzle back in the direction of the nozzle chamber due to the pressure difference. The excess pressure in the nozzle chamber of the bell cup and in the external rinse channel compared to the air pressure at the outlet of the paint nozzle prevents the backflow of coating material.

[0012] Within the scope of the present invention, it is known that different design dimensions of the rotary atomizer affect the pressure ratio between the air pressure at the outlet opening of the paint nozzle and the air pressure in the nozzle chamber of the bell cup and in the outer rinse channel, including the following design dimensions: Cross section of the central hole in the dispersion disc of the bell cup Diameter of the central hole of the dispersion disc holder Gap width between the dispersion disc and the overflow surface of the bell cup Gap width of the annular gap between the bell cup or dispersion disc holder and the paint nozzle Gap width of the annular gap between the paint nozzle and the inner wall of the nozzle chamber Gap width of the annular gap between the bell cup shaft and the inner paint tube The gap width of the annular gap of the external rinse chamber outside the bell cup shaft, and The gap width between the front of the shaping air ring and the rear of the bell cup

[0013] Therefore, in the present invention, the above-mentioned design dimensions of the rotary sprayer are preferably adapted to one another so that a desired pressure ratio is set so that the air pressure at the outlet opening of the paint nozzle during operation is always lower than the air pressure in the nozzle chamber of the bell cup and in the external rinse channel, in order to avoid any unwanted backflow of coating agent from the outlet opening of the paint nozzle back in the direction of the nozzle chamber.

[0014] In particular, the air pressure at the outlet of the paint nozzle is affected by the following design dimensions of the rotary atomizer: Cross section of the central hole in the dispersion disc of the bell cup Gap width between the dispersion disc and the overflow surface of the bell cup Gap width of the annular gap between the bell cup and the paint nozzle

[0015] On the other hand, the air pressure in the rear region of the bell cup system (for example in the nozzle chamber of the bell cup or in the external rinse channel) is influenced, among other things, by the following design dimensions of the rotary atomizer: Gap width of the annular gap between the bell cup or the dispersion disc holder of the bell cup and the paint nozzle Diameter of the central hole of the dispersion disc holder Gap width of the annular gap between the paint nozzle and the inner wall of the nozzle chamber Gap width of the annular gap between the bell cup shaft and the inner paint tube The gap width of the annular gap of the external rinse chamber outside the bell cup shaft, and The gap width between the front of the shaping air ring and the rear of the bell cup

[0016] Therefore, in the present invention, the above two groups of design dimensions are preferably adapted in a manner suitable for achieving a desired pressure ratio.

[0017] In a preferred embodiment of the present invention, the number of external rinse channels in the bell cup is less than 10, 9, 8, 7, 6, or even less than 5 to achieve a pressure ratio that prevents backflow. In particular, since the external rinse channels are typically arranged around the periphery of the bell cup and offset the disturbing backflow by providing flow resistance, a reduction in the number of external rinse channels increases the flow resistance, thereby contributing to achieving the desired pressure ratio. In this case, the external rinse channels are less than 4 mm in diameter to achieve a pressure ratio that prevents backflow. 2 , 6mm 2 , 10mm 2 , 15mm 2, 20mm 2 , 25mm 2 , 30mm 2 , or 35mm 2 The total cross-sectional area may be less than 1 / 2.

[0018] It has been found to be advantageous for the external rinse channels to each have an internal diameter of 1 mm-2 mm, in particular substantially 1.5 mm, in order to achieve a pressure ratio that prevents backflow. Here, an internal diameter of the external rinse channel that is too small is problematic, since it inhibits the external rinsing process. On the other hand, an internal diameter of the external rinse channel that is too large is problematic, since it promotes the undesirable backflow of paint within the bell cup system. Therefore, according to the present invention, an internal diameter range of 1 mm-2 mm for the external rinse channel is a good compromise.

[0019] In addition, it is particularly preferred that the outer rinse channels have a total length of 5 mm-15 mm, 7 mm-10 mm, or 8 mm-8.7 mm, respectively.

[0020] It has been shown to be advantageous if the external rinse channel is made up of several (e.g. two) straight tapped holes that meet and are angled relative to one another. This is advantageous from a manufacturing point of view, since the tapped holes can be produced by drilling, and also from a flow technology point of view, since the twist in the external rinse channel counteracts unwanted backflow of paint.

[0021] Preferably, the tap hole leading to the external rinse chamber of the bell cup is shorter than the tap hole on the paint nozzle side.

[0022] The shorter tap holes in the bell cup that connect to the external rinse chamber are preferably 0.5-2mm or 1.0-1.4mm long, while the longer tap holes on the paint nozzle side are preferably 5-10mm or 6-8mm long.

[0023] Furthermore, the external rinse chamber in the bell cup also affects the pressure conditions within the bell cup system. It is known that increasing the outer diameter of the external rinse chamber has a positive effect on the pressure conditions. Therefore, preferably, the outer diameter of the external rinse chamber in the bell cup is greater than 30.5 mm, 31 mm, 31.5 mm, 32 mm, or 32.5 mm.

[0024] Another important design dimension is the gap width of the gap between the overflow surface of the bell cup and the dispersion disc. Within the scope of the present invention, the gap width is preferably in the range of 0.1 mm-0.25 mm, in particular in the range of 0.15 mm-0.2 mm.

[0025] However, in the gap between the overflow surface of the bell cup and the dispersion disc, not only the gap width but also the gap length in the flow direction is important, so the gap length between the overflow surface of the bell cup and the dispersion disc is preferably in the range of 3 mm to 10 mm, 3.5 mm to 7.5 mm, or 4.5 mm to 5.5 mm.

[0026] As already mentioned above, the paint nozzle in the bell cup is located in a nozzle chamber formed by the bell cup. It has been found to be advantageous to increase the diameter of the nozzle chamber in order to increase the radial gap width between the paint nozzle and the inner wall of the nozzle chamber, which also helps to optimize the pressure ratio and avoid paint backflow. Thus, the nozzle chamber in the bell cup preferably has a diameter greater than 11 mm, 11.5 mm, 12 mm, 12.5 mm, 13 mm, or even greater than 13.3 mm. A nozzle chamber diameter of 13.4 mm has been shown to be particularly advantageous in all cases.

[0027] Another important design dimension of the rotary atomizer is the gap width of the axial gap between the rotary atomizer's shaping air ring and the rear of the bell cup. It has been shown to be advantageous to increase the axial gap width between the shaping air ring and the rear of the bell cup. Thus, the axial gap between the shaping air ring and the rear of the bell cup is preferably greater than 3.0 mm, 4 mm, 4.5 mm, 5 mm, or 5.2 mm, with a value of 5.3 mm being particularly advantageous. In particular, to favorably affect the pressure ratio and avoid backflow, the bell cup shaft is preferably exposed in the axial gap between the shaping air ring and the rear of the bell cup, preferably without an external cover.

[0028] The pressure conditions within the bell cup system are also influenced by the outer diameter of the paint nozzle, which preferably has an outer diameter at its free end of less than 4 mm, 3.5 mm, 3 mm, or even less than 2.8 mm, with outer diameters of 2.6 mm or 3.2 mm having been shown to be particularly advantageous.

[0029] In a preferred embodiment of the present invention, as known from the prior art, a dispersion disk holder is mounted as a separate component in the center of the bell cup, and a dispersion disk is mounted on the dispersion disk holder. The paint nozzle protrudes through a central hole in the dispersion disk holder, preferably having an internal diameter of substantially 3.2 mm or 3.8 mm. The annular gap between the paint nozzle and the surrounding dispersion disk holder preferably has a radial gap width of 0.2 mm to 0.6 mm, with a value of 0.3 mm having been shown to be particularly advantageous.

[0030] In addition to the annular gap between the paint nozzle and the distribution disc holder, the axial gap length is also worth mentioning, which is preferably in the range of 4.5 mm-8.5 mm or 5.5 mm-7.5 mm, with a value of 6.5 mm having been shown to be particularly advantageous.

[0031] In addition to the annular gap between the paint nozzle and the surrounding distribution disc holder, the axial cross section of the annular gap is also worth mentioning, which is preferably 2 mm 2 -7mm 2 , 3mm 2 -6mm 2 , or 4 mm 2 -5mm 2 It has a cross-sectional area of ​​.

[0032] Finally, in particular, the present invention does not claim protection only for the rotary sprayer described above. Rather, the present invention also claims protection for a corresponding operating method that provides, in addition to the above-mentioned design dimensions, specific operating parameters, such as the speed of the bell cup shaft, the flow rate of the coating agent, and the flow rate of the shaping air. The above-mentioned design dimensions and the above-mentioned operating parameters are preferably coordinated with each other so that desired pressure conditions are achieved within the bell cup system to avoid undesirable backflow of the coating agent within the bell cup system. For this reason, the air pressure at the outlet opening of the paint nozzle must be lower than the air pressure in the nozzle chamber of the bell cup and in the external rinse channel to prevent backflow of the coating agent.

[0033] Other advantageous further developments of the invention are indicated in the dependent claims and are explained in more detail below together with the description of preferred embodiments of the invention with reference to the drawings. [Brief explanation of the drawings]

[0034] [Figure 1] 1 shows a cross-sectional view of a rotary atomizer having a bell cup according to the present invention. [Figure 2] 2 shows an enlarged view of the area of ​​the dispersion disc holder in FIG. 1; [Figure 3] 3 shows an enlarged view of the area of ​​the gap between the dispersion disc and the overflow surface of the bell cup in FIG. 2. [Figure 4] 2 shows an enlarged view of the area of ​​the paint nozzle in FIG. 1; [Figure 5] 5 shows an enlarged view of the area of ​​the outlet opening of the paint nozzle in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0035] The drawings show a preferred embodiment of a rotary sprayer 1 that can be used in paint applications in paint plants for painting automotive body parts.

[0036] The rotary atomizer 1 has a bell cup shaft 2 which rotates during operation. The bell cup shaft 2 is hollow and is typically driven by a compressed air turbine, which is not shown for simplicity.

[0037] The bell cup 3 is screwed onto the free end of the bell cup shaft 2, as known per se from the prior art.

[0038] The paint to be applied is supplied from the rotary atomizer 1 via a paint tube 4 which extends coaxially within the hollow bell cup shaft 2 of the rotary atomizer.

[0039] A paint nozzle 5 is inserted into the free end of the paint tube 4. This nozzle is shown in Figures 4 and 5, and a similar configuration is described in DE 10 2009 037 604 A1. The paint nozzle 5 has, for example, an axially continuous paint channel 6, which guides the paint to be applied from the paint tube 4 to an outlet opening 7 of the paint nozzle 5. Furthermore, the paint nozzle 5 has a rinse aid channel 8, which branches in the flow direction into two rinse aid channels 9, 10. During the rinsing process, part of the rinse aid supplied via the rinse aid channel 8 is thus expelled axially forward through the rinse aid channel 9 to rinse the bell cup 3. Another part of the rinse aid branches off via the rinse aid channel 10 to rinse the nozzle chamber 11 surrounding the paint nozzle 5.

[0040] A dispersion disc holder 12 is attached to the center of the bell cup 3, and the dispersion disc holder 12 supports a dispersion disc 13, which is attached to the dispersion disc holder 12 with a plurality of bolts 14 arranged around the outer periphery.

[0041] In the center of the distribution disk 13 there is a central hole 15, through which a portion of the paint coming out of the paint nozzle 5 can flow and wet the front surface of the distribution disk 13 with paint during operation.

[0042] Meanwhile, most of the paint coming out of the paint nozzle 5 is dispersed radially outward by the dispersion disc 13, passes outward through the gap 16 between the dispersion disc 13 and the overflow surface 17 and reaches the spray edge 18 of the bell cup 3, from where the paint is finally sprayed.

[0043] In addition, the rotary sprayer 1 with bell cup 3 also allows for external rinsing of the outer peripheral surface 19 of the bell cup 3 in order to clean the outer peripheral surface 19 of the bell cup 3. For this purpose, external rinsing channels 20 are provided in the bell cup 3, arranged around the periphery and consisting of two tapped holes, one straight and one angled. The external rinsing channels 20 start from the nozzle chamber 11 and open into an external rinsing chamber 21, so that rinsing agent can flow outwards from the external rinsing chamber 21 to the outer peripheral surface 19 of the bell cup 3 during the rinsing process. This is known from the prior art.

[0044] Furthermore, it is worth noting that the rotary sprayer 1 comprises a shaping air ring 22, which is known per se from the prior art, in order to be able to shape the spray jet of paint delivered by the bell cup 3. To this end, the shaping air ring 22 is able to direct shaping air onto the outer peripheral surface 19 of the bell cup 3 from behind via an annular ring of shaping air nozzles 23. In particular, between the rear side of the bell cup 3 and the shaping air ring 22 there is a gap 24, which has a certain axial gap width.

[0045] Within the scope of the present invention, different design dimensions of the rotary atomizer 1 and the bell cup 3 are relevant to achieve the object of the present invention of varying the paint backflow in the bell cup 3. In particular, the following design dimensions can be mentioned: Diameter A of the central hole in the dispersion disc holder 12 of the bell cup 3 Gap width B of the gap 16 between the dispersion disc 13 and the overflow surface 17 of the bell cup 3 Gap width C of the annular gap 25 between the dispersion disc holder 12 of the bell cup 3 and the paint nozzle 5 Gap width D of the annular gap between the paint nozzle 5 and the inner wall of the nozzle chamber 11 Gap width E of the annular gap 27 between the paint tube 4 and the bell cup shaft 2 the gap width F of the annular gap 28 formed by the outer rinse chamber 21 of the bell cup 3, and Gap width G between the bell cup 3 and the shaping air ring 22

[0046] The above-mentioned design dimensions of the bell cup 3 or rotary sprayer are in this embodiment adapted to one another so that the air pressure at the outlet opening of the paint nozzle 5 is always lower during operation than the air pressure in the nozzle chamber 11 and in the external rinse channel 20 of the bell cup 3. This prevents any unwanted backflow of paint to the rear side.

[0047] Thus, the following values ​​for the individual design dimensions have proven advantageous: A=3.2mm or A=3.8mm, B=0.15mm-0.2mm, C=0.3mm, D=1.7mm, E=0.75mm, F=3.25mm, G=5.3mm. Within the scope of the present invention, deviations of ±30%, ±20%, ±10%, ±5%, or ±2% with respect to the above values ​​are possible.

[0048] Furthermore, in particular the number of external rinse channels 20 has been reduced compared to the prior art to six external rinse channels 6, which also has a positive effect on the pressure conditions.

[0049] The present invention is not limited to the preferred embodiments described above. Rather, the invention claims subject matter and features recited in the dependent claims independently of the claims to which they refer, and in particular without the features of the main claim. Thus, the present invention encompasses different aspects of the invention that are protected independently of each other.

[0050] [Note] [Appendix 1] A rotary sprayer (1) for applying a spray jet of a coating agent, in particular a paint, to a part, in particular a motor vehicle body part, comprising: a) a shaping air ring that emits shaping air to form the spray jet of the coating agent; b) a hollow bell cup shaft (2) that rotates during operation; c) a paint tube (4) disposed substantially coaxially within the hollow bell cup shaft (2), the bell cup shaft (2) and the inner paint tube (4) radially surrounding an annular gap (27) having a specific gap width (E); d) a paint nozzle (5) arranged substantially coaxially within the paint tube (4) and discharging the coating agent through an outlet opening (7) so that it is applied substantially axially; e) a bell cup (3) mounted on the bell cup shaft (2) and rotating during operation, e1) a gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3) having a specific gap width (G) in the axial direction; e2) a central hole for axial penetration of the paint nozzle (5) having an annular gap (25) between the bell cup (3) and the paint nozzle (5) with a specific gap width (C) in the radial direction; e3) an annular spray edge (18) for spraying the coating agent; e4) Outer surface (19), e5) an external rinse chamber (21) behind the bell cup (3) for rinsing the outer peripheral surface (19) with a rinse agent, the external rinse chamber (21) forming an annular gap (28) with a specific gap width (F) in the radial direction outside the bell cup shaft (2); e6) a plurality of external rinse channels (20) in the bell cup (3) between the paint nozzle (5) and the external rinse chamber (21) for supplying rinse agent from the paint nozzle (5) to the outer peripheral surface (19) of the bell cup (3) for external rinsing of the bell cup (3); e7) a nozzle chamber (11) behind the bell cup (3) for receiving the paint nozzle (5) with an annular gap (26) having a specific radial gap width (D) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); e8) an overflow surface (17) at the front side, over which the coating material to be applied coming from the outlet opening (7) of the paint nozzle (5) flows outwardly towards the spray edge (18) of the bell cup (3) during operation; e9) a dispersion disk (13) for dispersing the coating material coming out of the outlet opening (7) of the paint nozzle (5), The dispersion disk (13) is disposed at the front side within the bell cup (3), The dispersion disc (13) directs the coating material coming from the paint nozzle (5) partly radially outwardly towards the overflow surface (17) of the bell cup (3) and partly axially towards the end face of the dispersion disc (13) through a central hole (15) in the dispersion disc (13); The dispersion disc (13) together with the overflow surface (17) of the bell cup (3) encloses a gap (16) having a specific gap width (B), Distributed disk (13), e10) a dispersion disc holder (12) arranged in the bell cup (3) and having a central hole with a specific diameter (A), the dispersion disc (13) being mounted on the dispersion disc holder (12); a bell cup (3) comprising: Equipped with f) the rotary sprayer (1) is designed so that the air pressure at the outlet opening (7) of the paint nozzle (5) during operation is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the external rinse channel (20), in order to prevent the coating agent from flowing back from the outlet opening (7) of the paint nozzle (5) in the direction of the nozzle chamber (11) as a result of a pressure difference. Rotary sprayer (1).

[0051] [Appendix 2] a) the diameter (A) of the central hole in the dispersion disc holder (12) of the bell cup (3); b) the gap width (B) of the gap (16) between the dispersion disc (13) and the overflow surface (17) of the bell cup (3); c) the gap width (C) of the annular gap (25) between the bell cup (3) and the paint nozzle (5); d) the gap width (D) of the annular gap (26) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); e) the gap width (E) of the annular gap (27) between the bell cup shaft (2) and the inner paint tube (4); f) the gap width (F) of the annular gap (28) of the outer rinse chamber (21) outside the bell cup shaft (2), and g) the gap width (G) of the gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3); The design dimensions of the rotary sprayer (1) are adapted to one another so that the air pressure at the outlet opening (7) of the paint nozzle (5) during operation is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the outer rinse channel (20). 1. A rotary atomizer (1) as described in Appendix 1.

[0052] [Appendix 3] a) the number of the external rinse channels (20) in the bell cup (3) is less than 10, 9, 8, 7, 6 or 5 to achieve a pressure ratio that prevents backflow; and / or b) To achieve a pressure ratio that prevents backflow, the external rinse channel should be 4 mm 2 , 6mm 2 , 10mm 2 , 15mm 2 , 20mm 2 , 25mm 2 , 30mm 2 , or 35mm 2 having a total cross-sectional area of ​​less than 3. A rotary atomizer (1) according to claim 1 or 2.

[0053] [Appendix 4] a) the outer rinse channels (20) each have an internal diameter of 1 mm-2 mm, in particular substantially 1.5 mm, in order to achieve a pressure ratio that prevents backflow; and / or b) the outer rinse channels (20) have a total length of 5 mm-15 mm, 7 mm-10 mm, or 8 mm-8.7 mm, respectively; 4. A rotary atomizer (1) according to any one of claims 1 to 3.

[0054] [Appendix 5] a) the external rinse channels (20) each consist of a plurality of, in particular exactly two, straight tapped holes which meet and are inclined relative to one another, and / or b) the tap hole of the bell cup (3) opening into the external rinse chamber (21) is shorter than the tap hole on the paint nozzle side; and / or c) the shorter tap holes of the bell cup (3) opening into the external rinse chamber (21) have a length of 0.5 mm-2 mm or 1.0 mm-1.4 mm, respectively; and / or d) The longer tap holes on the paint nozzle side have lengths of 5 mm-10 mm or 6 mm-8 mm, respectively; 5. A rotary atomizer (1) according to any one of claims 1 to 4.

[0055] [Appendix 6] To achieve a pressure ratio that avoids backflow, the external rinse chamber (21) in the bell cup (3) has an outer diameter greater than 30.5 mm, 31 mm, 31.5 mm, 32 mm, or 32.5 mm. 6. A rotary atomizer (1) according to any one of claims 1 to 5.

[0056] [Appendix 7] a) the gap width (B) of the gap (16) between the overflow surface (17) of the bell cup (3) and the dispersion disc (13) is in the range of 0.1 mm-0.25 mm, in particular in the range of 0.15 mm-0.2 mm; and / or b) the gap (16) between the overflow surface (17) of the bell cup (3) and the dispersion disc (13) has a gap length in the flow direction in the range of 3 mm-10 mm, 3.5 mm-7.5 mm, or 4.5 mm-5.5 mm; 7. A rotary atomizer (1) according to any one of claims 1 to 6.

[0057] [Appendix 8] In order to increase the radial gap width (D) between the paint nozzle (5) and the inner wall of the nozzle chamber (11) and thereby achieve a pressure ratio to reduce backflow, the nozzle chamber (11) in the bell cup (3) has an outer diameter of 11 mm, 11.5 mm, 12 mm, 12.5 mm, more than 13 mm, or more than 13.3 mm, in particular substantially 13.4 mm. 8. A rotary atomizer (1) according to any one of claims 1 to 7.

[0058] [Appendix 9] a) the axial gap (24) between the shaping air ring (22) and the rear side of the bell cup (3) has an axial gap width (G) greater than 3.0 mm, 4 mm, 4.5 mm, 5 mm, or 5.2 mm, in particular substantially 5.3 mm, in order to achieve a pressure ratio that avoids backflow; and / or b) without an external cover, the bell cup shaft (2) is exposed in the axial gap (24) between the shaping air ring (22) and the rear side of the bell cup (3) to achieve a pressure ratio that avoids backflow; 9. A rotary atomizer (1) according to any one of claims 1 to 8.

[0059] [Appendix 10] The paint nozzle (5) has an outer diameter at its free end of less than 4 mm, 3.5 mm, 3 mm, or 2.8 mm, in particular substantially 2.6 mm or 3.2 mm; 10. A rotary atomizer (1) according to any one of claims 1 to 9.

[0060] [Appendix 11] a) the central hole in the dispersion disc holder (12) has a diameter (A) of substantially 3.2 mm or 3.8 mm; and / or b) the annular gap (25) between the inner paint nozzle (5) and the outer distribution disk holder (12) has a radial gap width of 0.2 mm-0.6 mm, in particular substantially 0.3 mm; and / or c) the annular gap (25) between the inner paint nozzle (5) and the outer distribution disk holder (12) has an axial gap length of 4.5 mm-8.5 mm or 5.5 mm-7.5 mm, in particular substantially 6.5 mm; and / or d) The annular gap (25) between the inner paint nozzle (5) and the outer distribution disc holder (12) is 2 mm in axial cross section. 2 -7mm 2 , 3mm 2 -6mm 2 , or 4 mm 2 -5mm 2 having a cross-sectional area of 11. A rotary atomizer (1) according to any one of claims 1 to 10.

[0061] [Appendix 12] 12. A method of operation for a rotary atomizer (1) according to any one of claims 1 to 11, comprising: the air pressure at the outlet opening (7) of the paint nozzle (5) is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the external rinse channel (20) to prevent the coating agent from flowing backward from the outlet opening (7) of the paint nozzle (5) towards the nozzle chamber (11) due to a pressure difference. How to drive.

[0062] [Appendix 13] a) the bell cup shaft (2) rotates at a specific speed; b) the paint nozzle (5) emits the coating agent at a specific flow rate; c) the shaping air ring (22) emits the shaping air at a specific flow rate; and d) the following design dimensions and operating parameters are matched to one another so that the air pressure at the outlet opening (7) of the paint nozzle (5) is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the outer rinse channel (20), in order to prevent the coating agent from flowing back from the outlet opening (7) of the paint nozzle (5) in the direction of the nozzle chamber (11) as a result of a pressure difference: d1) the diameter (A) of the central hole in the dispersion disc holder (12) of the bell cup (3); d2) the gap width (B) of the gap (16) between the dispersion disc (13) and the overflow surface (17) of the bell cup (3); d3) the gap width (C) of the annular gap (25) between the bell cup (3) and the paint nozzle (5); d4) the gap width (D) of the annular gap (26) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); d5) the gap width (E) of the annular gap (27) between the bell cup shaft (2) and the inner paint tube (4); d6) the gap width (F) of the annular gap (28) of the outer rinse chamber (21) outside the bell cup shaft (2); d7) the gap width (G) of the gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3); d8) the speed of the bell cup shaft (2); d9) the flow rate of the coating agent; and d10) the flow rate of the shaping air; The operating method described in Appendix 12.

[0063] [Appendix 14] A coating robot, in particular a painting robot, comprising a serial or parallel robot mechanism having a plurality of, in particular five, six or seven, movable axes and a rotary sprayer (1) according to any one of claims 1 to 11. [Explanation of symbols]

[0064] 1 rotary sprayer 2 Rotary sprayer bell cup shaft 3 Bell Cup 4 Rotary Sprayer Paint Tubes 5 Rotary sprayer paint nozzle 6. Paint channel in the paint nozzle 7. Outlet opening of the paint nozzle 8-10 Rinse aid channel in paint nozzle 11 Nozzle chamber behind the bell cup 12 Bell Cup Dispersion Disc Holder 13 Bell Cup Dispersion Disc 14 Bolts for connecting the dispersion disc to the dispersion disc holder 15 Central hole in the dispersion disc of the bell cup 16 Gap between dispersion disc and overflow surface of bell cup 17 Bell cup overflow surface 18 Spray rim of bell cup 19 Outer surface of bell cup 20 External rinse channel of bell cup 21 Bell cup external rinse chamber 22 Shaping air ring for rotary sprayer 23 Shaping Air Nozzle 24 Gap between bell cup and shaping air ring 25 Annular gap between dispersion disc holder and paint nozzle in bell cup 26 Annular gap between paint nozzle and nozzle chamber 27 Annular gap between paint tube and bell cup shaft 28 Annular gap formed by external rinse chamber A is the diameter of the central hole in the dispersion disc holder B Gap width between the dispersion disc and the overflow surface of the bell cup C Gap width of the annular gap between the dispersion disc holder in the bell cup and the paint nozzle D Radial gap width of the annular gap between the paint nozzle and the nozzle chamber E Gap width of the annular gap between the paint tube and the bell cup shaft F radial gap width of the annular gap formed by the external rinse chamber G Axial gap width between the bell cup and the shaping air ring

Claims

1. A rotary sprayer (1) for applying a spray jet of a coating agent to a part, comprising: a) a shaping air ring that emits shaping air to form the spray jet of the coating agent; b) a hollow bell cup shaft (2) that rotates during operation; c) a paint tube (4) coaxially arranged within the hollow bell cup shaft (2), the bell cup shaft (2) and the inner paint tube (4) surrounding an annular gap (27) having a specific gap width (E) in the radial direction; d) a paint nozzle (5) arranged coaxially within the paint tube (4) and discharging the coating agent through an outlet opening (7) for application in the axial direction; e) a bell cup (3) mounted on the bell cup shaft (2) and rotating during operation, e1) a gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3) with a specific gap width (G) in the axial direction; e2) a central hole for axial passage of the paint nozzle (5) having an annular gap (25) between the bell cup (3) and the paint nozzle (5) with a specific gap width (C) in the radial direction; e3) an annular spray edge (18) for spraying the coating agent; e4) outer peripheral surface (19), e5) an external rinse chamber (21) behind the bell cup (3) for rinsing the outer peripheral surface (19) with a rinse agent, the external rinse chamber (21) forming an annular gap (28) with a specific gap width (F) in the radial direction outside the bell cup shaft (2); e6) a plurality of external rinse channels (20) in the bell cup (3) between the paint nozzle (5) and the external rinse chamber (21) for supplying rinse agent from the paint nozzle (5) to the outer peripheral surface (19) of the bell cup (3) for external rinsing of the bell cup (3); e7) a nozzle chamber (11) behind the bell cup (3) for receiving the paint nozzle (5) with an annular gap (26) having a specific radial gap width (D) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); e8) an overflow surface (17) at the front side, over which the coating material to be applied coming from the outlet opening (7) of the paint nozzle (5) flows outwardly towards the spray edge (18) of the bell cup (3) during operation; e9) a dispersion disk (13) for dispersing the coating material coming out of the outlet opening (7) of the paint nozzle (5), The dispersion disc (13) is located at the front side in the bell cup (3), The dispersion disc (13) directs the coating material coming from the paint nozzle (5) partly radially outwards towards the overflow surface (17) of the bell cup (3) and partly axially towards the end face of the dispersion disc (13) through a central hole (15) in the dispersion disc (13); The dispersion disc (13) together with the overflow surface (17) of the bell cup (3) encloses a gap (16) having a specific gap width (B), Distributed disk (13), e10) a dispersion disc holder (12) arranged in the bell cup (3) and having a central hole with a specific diameter (A), the dispersion disc (13) being mounted on the dispersion disc holder (12); a bell cup (3) comprising: Equipped with f) the rotary sprayer (1) is designed so that the air pressure at the outlet opening (7) of the paint nozzle (5) during operation is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the external rinse channel (20), in order to prevent the coating agent from flowing back from the outlet opening (7) of the paint nozzle (5) in the direction of the nozzle chamber (11) as a result of a pressure difference; f1) the diameter (A) of the central hole in the dispersion disc holder (12) of the bell cup (3); f2) the gap width (B) of the gap (16) between the dispersion disc (13) and the overflow surface (17) of the bell cup (3); f3) the gap width (C) of the annular gap (25) between the bell cup (3) and the paint nozzle (5); f4) the gap width (D) of the annular gap (26) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); f5) the gap width (E) of the annular gap (27) between the bell cup shaft (2) and the inner paint tube (4); f6) the gap width (F) of the annular gap (28) of the outer rinse chamber (21) outside the bell cup shaft (2), and f7) the gap width (G) of the gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3); the design dimensions of the rotary sprayer (1) are adapted to one another so that the air pressure at the outlet opening (7) of the paint nozzle (5) during operation is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the outer rinse channel (20); g) to achieve a pressure ratio to avoid backflow, the outer rinse channels (20) each have an inner diameter of 1 mm-2 mm, and the outer rinse channels (20) each have a total length of 5 mm-15 mm; Rotary atomizer (1).

2. a) the number of said external rinse channels (20) in said bell cup (3) is less than 10 in order to achieve a pressure ratio that prevents backflow, and / or b) To achieve a pressure ratio that prevents backflow, the external rinse channel must be 35 mm ２ having a total cross-sectional area of ​​less than A rotary atomizer (1) according to claim 1.

3. a) the external rinse channels (20) each consist of a plurality of linear tapped holes that meet and are inclined relative to one another; and / or b) the tap hole of the bell cup (3) opening into the external rinse chamber (21) is shorter than the tap hole on the paint nozzle side; and / or c) the shorter tap holes of the bell cup (3) opening into the external rinse chamber (21) each have a length of 0.5 mm-2 mm; and / or d) The longer tap holes on the paint nozzle side each have a length of 5 mm to 10 mm; A rotary atomizer (1) according to claim 1 or 2.

4. In order to achieve a pressure ratio to avoid backflow, the external rinse chamber (21) in the bell cup (3) has an outer diameter greater than 30.5 mm. A rotary atomizer (1) according to any one of claims 1 to 3.

5. a) the gap width (B) of the gap (16) between the overflow surface (17) of the bell cup (3) and the dispersion disc (13) is in the range of 0.1 mm - 0.25 mm; and / or b) the gap (16) between the overflow surface (17) of the bell cup (3) and the dispersion disc (13) has a gap length in the flow direction in the range of 3 mm-10 mm; A rotary atomizer (1) according to any one of claims 1 to 4.

6. the nozzle chamber (11) in the bell cup (3) has an outer diameter of more than 11 mm in order to increase the radial gap width (D) between the paint nozzle (5) and the inner wall of the nozzle chamber (11) and thereby achieve a pressure ratio to reduce backflow; A rotary atomizer (1) according to any one of claims 1 to 5.

7. a) the axial gap (24) between the shaping air ring (22) and the rear side of the bell cup (3) has an axial gap width (G) greater than 3.0 mm to achieve a pressure ratio that avoids backflow; and / or b) without an external cover, the bell cup shaft (2) is exposed in the axial gap (24) between the shaping air ring (22) and the rear side of the bell cup (3) to achieve a pressure ratio that avoids backflow; A rotary atomizer (1) according to any one of claims 1 to 6.

8. The paint nozzle (5) has an outer diameter at its free end of less than 4 mm. A rotary atomizer (1) according to any one of claims 1 to 7.

9. a) the central hole in the dispersion disc holder (12) has a diameter (A) of 3.2 mm or 3.8 mm; and / or b) the annular gap (25) between the inner paint nozzle (5) and the outer distribution disc holder (12) has a radial gap width of 0.2 mm-0.6 mm; and / or c) the annular gap (25) between the inner paint nozzle (5) and the outer distribution disc holder (12) has an axial gap length of 4.5 mm-8.5 mm; and / or d) the annular gap (25) between the inner paint nozzle (5) and the outer distribution disc holder (12) is 2 mm in axial cross section; ２ -having a cross-sectional area of ​​7 mm A rotary atomizer (1) according to any one of claims 1 to 8.

10. 10. A method of operating a rotary atomizer (1) according to any one of claims 1 to 9, comprising: the air pressure at the outlet opening (7) of the paint nozzle (5) is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the external rinse channel (20) to prevent the coating agent from flowing backward from the outlet opening (7) of the paint nozzle (5) in the direction of the nozzle chamber (11) due to a pressure difference. How to drive.

11. a) the bell cup shaft (2) rotates at a specific speed; b) the paint nozzle (5) emits the coating agent at a specific flow rate; c) the shaping air ring (22) emits the shaping air at a specific flow rate; and d) the following design dimensions and operating parameters are matched to one another so that the air pressure at the outlet opening (7) of the paint nozzle (5) is lower than the air pressure in the nozzle chamber (11) of the bell cup (3) and in the outer rinse channel (20), in order to prevent the coating agent from flowing back from the outlet opening (7) of the paint nozzle (5) in the direction of the nozzle chamber (11) as a result of a pressure difference: d1) the diameter (A) of the central hole in the dispersion disc holder (12) of the bell cup (3); d2) the gap width (B) of the gap (16) between the dispersion disc (13) and the overflow surface (17) of the bell cup (3); d3) the gap width (C) of the annular gap (25) between the bell cup (3) and the paint nozzle (5); d4) the gap width (D) of the annular gap (26) between the paint nozzle (5) and the inner wall of the nozzle chamber (11); d5) the gap width (E) of the annular gap (27) between the bell cup shaft (2) and the inner paint tube (4); d6) the gap width (F) of the annular gap (28) of the outer rinse chamber (21) outside the bell cup shaft (2); d7) the gap width (G) of the gap (24) between the front side of the shaping air ring (22) and the rear side of the bell cup (3); d8) the speed of the bell cup shaft (2); d9) the flow rate of the coating agent; and d10) the flow rate of the shaping air; The operating method according to claim 10.

12. A coating robot comprising a serial or parallel robot mechanism with multiple moving axes and a rotary sprayer (1) according to any one of claims 1 to 9.

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