DE2033951A1 - Atomizer nozzle for a system for spraying paint, enamel or the like - Google Patents

Description

Dr. ing. Walter Abitz.

Dr. Dieter F. Morf
Dr. Hans-A. Browns

8 Munich 86, Hewtnauerstr. 28

July 8, 1970 GAS 112 + 113

TUNZINI-SAMES
21, rue Jean Mace, 38 Grenoble, France

Atomizer nozzle for a system for spraying paint, enamel or the like

The present "invention relates to a spray nozzle for a Paint spray gun and in particular an electrostatic spray nozzle for applying paint layers, enamel layers, and the same. '

Such spray nozzles have already been made, -which one had first ring body for dispensing the liquid product to be sprayed, and a second ring body concentric thereto for the atomizing air, the first Annular body expands forward and a centrally arranged atomizer is arranged in it, which has an annular Forms outlet channel for the liquid to be atomized. These embodiments were essentially thereon turned off to bring about a meeting of the liquid jet and the air jet by the liquid in

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a preparatory phase for atomization has been carried out, in which it was in the form of a thin layer. Such constructed atomizing nozzles are for a proper Atomization suitable for outputs in the order of magnitude of 10 to a maximum of 20 liters / hour. The maximal The diameter dimension of the central atomizer is between 5 and 8 mm, with such dimensions and the there is no particular problem in achieving satisfactory atomization. If, on the other hand, a higher performance is sought, for example twice or four times the stated performance, then has Experience has shown that a simple corresponding enlargement of the atomizer nozzle is not sufficient for this. It various deficiencies occur, the most important of which is a reduction in the outflow of fluid which phenomena occur periodically jerky jets of liquid with variable power, which lead to a lead to poor atomization at the time of maximum power output, which is noticeably higher than the mean Power output. This deficiency is partly due to it It helped that the average power was reduced or the nozzle was overdimensioned accordingly.

The present invention! one of the tasks is to create a high-performance atomizing nozzle, • which emits a continuous flow and an optimal one Allows atomization. Further lies the present invention the object of the invention is to provide an atomizing nozzle of this type which is suitably dimensioned to accommodate an increased To deliver the service without showing the defects listed above.

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The present invention is based on the finding that the liquid discharge from the atomizing nozzle is more active, the greater the charge loss that occurs is. If the charge loss is too weak, the suction effect caused by the pressure drop in the atomizing air will result to intermittent and periodic vacancies in the nozzle's annular channel. This loss of charge leads to one. Braking, which is caused by the wall of the annular channel of the nozzle, this braking the length of the Channel proportional and inversely to the cross section of the channel is proportional; the braking is also the viscosity of the Liquid proportional. If you increase this braking or this loss of charge, that means you reduce the cross-section of the annular channel of the nozzle and / or if the longitudinal dimension of this channel is increased, it is found that the appearance the decrease in discharge has been suppressed. The outflow will be even and the atomization will be great regardless of the power satisfactory.

One is therefore led to believe that the best results will be obtained with a long and narrow nozzle channel. There is, however, a limit, since with paint and in particular with enamel, the product to be atomized generally entrains agglomerates, which are harmful obstacles both to the quality of the atomization and to the time required for cleaning the nozzle, which leads to corresponding problems Business interruption leads. One is therefore restricted with regard to increasing the charge loss. However, there is another limit value which, as far as the liquid is concerned, results from the surface tension. It has in fact been found that the three dimensions of the ring channel, namely the

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Longitudinal dimensions, circumferential dimensions and thickness are decisive for creating a long and narrow cavity in which important phenomena based on the surface tension of the liquid take place. Under certain circumstances, if the longitudinal dimension is dimensioned sufficiently large, the circumferential dimension is not chosen too high and the thickness is sufficiently reduced, an immobile liquid layer is achieved in the nozzle channel without any outflow and therefore only under the action of surface tension forces. Experiments have been carried out with a liquid of medium viscosity and surface tension, namely a viscosity of 25 for a # 4 Ford cup and a surface tension of 25 to 35 dynes / cm, which indicate that a satisfactory Atomization is obtained when, in the normal position of the nozzle with respect to gravity, the dimensions. Solutions of the nozzle are chosen so that they. ensure the formation of a stable liquid layer in the cavity of the annular channel of the nozzle. The investigation of this state also allows the determination that for a given circumferential dimension and a given thickness of the annular channel of the nozzle, an increase in the longitudinal dimension above a certain critical value only brings a determinable but in any case no significant effect. In other words, if the curves for the state of formation of a stable layer are plotted for a limited number of circumferential dimensions of the nozzle, a first curve section results, starting from the zero point, where every increase in the longitudinal dimension corresponds to a corresponding increase in thickness , and then a second curve section, where each enlargement of the longitudinal dimension of the ring canal only

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correspond to very small increases in the thickness dimension of the annular channel. This means that it is expedient to do that To choose the thickness of the channel in the first curve section, or even better in the connecting zone of the two curve sections, because then any increase in the longitudinal dimension no longer leads to a noticeable increase in the thickness of the channel.

About the state of an immobile layer of fluid in the above Obtaining the DUsenkanal under the action of surface tension alone results according to the Vis- (j cosity and surface tension of the liquid design values for the annular channel of the nozzle, which are either of the same order of magnitude as those mentioned above Design limit values for a non-occurrence of a reduction in discharge, or differently according to a higher pressure loss or a smaller pressure loss compared to the Pressure loss limit value if there is no discharge reduction.

In addition, the present invention provides the teaching of providing the dimensions of the annular channel of the nozzle (length, diameter and thickness) in such a way that in the area of the atomizing liquids the charge loss occurs in the immediate vicinity of the highest charge loss, which results for the two charge losses, one of which the limit value for the non-occurrence of a decrease in discharge and the other for the formation of a stable layer as a result . corresponds to the surface tension.

The present invention is also based on the object of forming an outflow that is as regular as possible along the outer circumference of the said atomizing nozzles

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To achieve outlet. According to the present invention, the central atomizer is arranged in an axially sliding manner in the ring body and is opposed to a rear position, or to the closed position ^! The ring body is pressed by a return spring, which compensates for the effect of the liquid pressure on the atomizer in such a way that an opening of the ring body is ensured which corresponds to the required power and the flow characteristics of the liquid. Preferably, the axially sliding attachment of the ring body allows limited radial movement. The first measure enables the arrangement of an annular channel, the cross-section of which automatically depends on the amount to be atomized and the type of liquid to be atomized, so that a liquid layer with an essentially constant thickness is automatically formed around the outlet, which is required by the Performance and the viscosity of the liquid to be atomized depends. The second measure makes it possible to improve the formation of a uniform outflow through the effect of self-centering, which is caused by the liquid to be atomized, since the exact position of the atomizer is determined by the liquid itself; In this way it is not necessary to carry out the components and the assembly with extreme precision in order to achieve the desired even outflow. Furthermore

one would, regardless of the care that is expended for the implementation of a very precise axial sliding arrangement, never achieve a corresponding annular space, as such a Riagraum, which dimensions of a few tenths of a millimeter in the radial direction for weak outflow. Stungen has a precision in the order of a few hundredths of a millimeter, which in terms of

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to the movement of the atomizer and the presence of abrasive particles can never be retained during operation.

The present invention | is then based on some ■ Embodiments described in connection with the accompanying drawings. Show it:

Figure 1 is a section through a first embodiment of the [Invention »·

Figure 2 is a perspective view,

FIG. 3 shows a section through a second embodiment,

FIG. 4 shows a section through a further embodiment,

FIG. 5 shows a section with a partially schematic representation and with two different scales of an automatic paint spraying system when the system is at a standstill,

Figure 6 is a partial view of the spray nozzle according to Figure 5 in the operating position, ·

Figure 7 is a partially sectioned view of a paint spray gun of the present invention] and

FIG. 8 shows a section through a further embodiment of the spray nozzle.

According to FIGS. 1 and 2, the spray nozzle of the present invention consists of a tube 1 which has an axial opening 2 for the passage of liquid and a side

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Has bore 3 for the spray air. At the end of the opening a nozzle body 4 is arranged, the axial opening 5 of which extends towards the outside into a cylindrical area 5 ' expanded, in which one end of the hollow cylinder 6 of an atomizer 7 is arranged. The atomizer 7 has a outer section, which is designed as a truncated cone 8 and a part also designed as a truncated cone 9 of the ring body 4 is opposite. In this way, a line for the liquid through the axial channel 5, the lateral bores 10 of the atomizer 7 and the truncated cone-shaped outwardly opening annular channel 11 is created.

A cap 12 delimits together with the tube 1 and the nozzle body 4 air distribution chambers 13 and 14. The atomizing air occurs in an annular fluidized bed between the End of the ring body and the end of the cap 12 from.

The present (invention is based on the shape of the ring channel turned off, whereby the following terms are used:

1 is the distance in the longitudinal direction between points A uhd

£ the circumferential dimension of the channel at the location of the Outlet,

e_ the thickness of the ring channel, that is, the distance between the two sides 8 and 9 of the ring channel.

In this embodiment the charge loss is considerable and the circumferential dimension £ is selected as the puncture of the power to be measured, this circumferential dimension £ being measured in centimeters and between 0.05 and 0.2 of the value of the amount of liquid to be atomized,

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measured in liters / hour. In other words, every centimeter of the circumferential dimension corresponds to a liquid output between 5 l / h and 20 l / h. For example, for a paint with a viscosity of 25 to 35 seconds for a # 4 Ford cup and a surface tension of 25 to 35 dynes / cm for a circumferential dimension of 6 cm, .1 has a dimension of 0.4 cm, while the thickness e_ is 0.04 cm. The liquid output can be between 30 and 120 l / h. The annular channel, which here has an essentially constant thickness, has a ratio between thickness e_ and longitudinal dimension l ^ _t which is between 1/20 and 1/10 and preferably between 1/15 and 1/7. ·

In Figure 3, the corresponding components are shown with the same reference numerals as in Figure 1, the difference being to the latter is that the thickness of the annular channel is no longer constant and the walls 8 and 9 of the ring channel converge against each other. However, Ea applies the previously mentioned feature, -according to which of the Charge loss should be smaller than that for the limit value for the absence of a decrease in discharge, where- a stable layer forms in the vicinity of this limit value as a result of the surface tension. That this characteristic is only obtained when the angle OC is between the walls 8 and 9 is less than 5 °, is shown from it. As soon as this angle is exceeded, the appearance of a reduction in flow or non-flow occurs formation of a stable layer.

Instead of an annular channel of the nozzle, which also expands as shown in FIGS. 1 and 2, the annular channel can be

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mass Figure 4 through a cylindrical ring channel. 40 formed be, which between the cylindrical atomizer 41 and the equally cylindrical ring body 42 is formed is.

In Figure 5 is an atomizing nozzle according to the present Invention shown, which has an annular body 51, which on the inflow side a first converging - diverging Has channel 52, as well as a second portion 53 with a cylindrical shape and a third end portion 54, which widens towards the outside like a truncated cone. The cylindrical area 53 accommodates a cylindrical sleeve 55 which is provided with a transverse wall 56 and with lateral openings 57 for the liquid to be atomized to pass through is. The transverse wall 56 of the sleeve 55 has an axial opening, on, through which an axially arranged rod 58 passes with a limited radial distance, which on its inside is provided with a shoulder 59 and outside the. Sleeve 55 with a threaded end portion which an atomizer 60 is attached. A compression spring 61 is between the transverse wall 56 of the sleeve 55 and the shoulder

59 of the axially lying rod 58 is arranged. The atomizer

60 is designed in the shape of a truncated cone, its larger diameter being essentially as large as the larger diameter of the conical region 54 of the annular body 51. The cone angle of the ring body 51 and that of the atomizer 60 are slightly different from each other, in such a sense that the cone angle of the ring body 51 is smaller than that of the atomizer 60, so that an annular channel is formed which extends from the inflow end to the outflow end narrows in the radial direction and, in particular, when the atomizer 60 is in the retracted position (FIG. 5), it results in a complete discharge at the end of the outlet. Of the

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Annular body 51 is fastened in a holder 62 which has a connection device to external supply sources, namely an axial connection 63 for the product to be atomized, a side connection 64 for the supply of the atomizing air, and a side auxiliary discharge connection 65, which is connected with a line 66 is in communication. The on _r-circuit 64 performs to a distribution chamber 67 which communicates via arranged inclined lines 68 to a second chamber 69 between the support 62 and a cap 70 in connection, which is held by a nut 71, wherein the output for the atomizing air through a second annular outlet is formed, which is concentric to the outlet for the liquid and is limited by a cylindrical portion 72a of the ring body 51 and the front part 72b, which is opposite the cap 70, [. The arrangement of lines, which are inclined in accordance with the tangents to the cylindrical chamber 72a, allows the formation of eddies of the atomizing air, which is particularly advantageous. ■

In the illustrated embodiment, the atomizer nozzle used in an automatic system and the color connection 63 is with a color supply 73 with the interposition of a Connected to pump 74, which is driven by a motor 75, and a line 76, while the connection 64 for the atomizing air in a manner known per se via a pipeline 77 with a compressed air distribution system 78 in connection stands. As can be seen, the branch line 66, which leads to the third connection 65, is provided with a three-way valve. 79 in connection, the other two outlets of which are connected to a return line 80 of the pump 74 and an outlet line 81 in FIG Connected.

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The mode of operation of this system is described below : '

In the position of the system in which the dye feed is interrupted (Figure 5), that is, in the position in which the pump 74 is switched off, the atomizer 60 pressed against the ring body 51 and the atomizer nozzle is closed in this way at one point, which is closest to the atomization point. In this position the nozzle body could also be cleaned Circulating a solvent under low pressure can be made, which through the discharge line 66 and the Outlet line 81 is drained. During the operation of the feed pump 74, a pressure is built up in the paint supply line and equally on the inlet-side wall of the atomizer 60, whereby both the exit of the paint as compression of the spring 61 (Figure 6) is also caused. The pump 74 is generally a more variable pump Whatever the properties of the paint, the power and outlet of the atomizer 60 is adjusted so that that the desired power is delivered, the degree of opening of the atomizer being a function of the viscosity the color changes. For very viscous paints, the outlet of the atomizer 60 is larger than in the case of a lighter one liquid dye, for which the charge losses in the annular space between the atomizer 60 and the annular body 51 are lower. As can be seen due to the arrangement, which is a slight radial displacement of the axially lying Permitted rod 58, which is arranged in the sleeve 55 and carries the atomizer 60, an automatic centering ' tion of the atomizer 60 ensured by the liquid pressure, which against the rear and side atomization

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It can also be seen that the double-tapered design allows not only a closure at the most distant point of the paint pipe and as close as possible to the atomization point, but also the formation of an annular channel which narrows increasingly from the inflow side to the outflow side . This design has a twofold advantage that it allows a verachluaa at the exact point of the atomization during the standstill of the pump, i.e. a very precisely defined termination of the atomization, while in known arrangements the atomization continues for some time after the pump has stopped lasts, and also a better stability of the outflow as a result of the existing conduit convergence, which causes an increasing constriction in the thickness of the annular flow. As can be seen, the initial tension of the spring 61 (atomizer 60 closed) is adjustable by tightening or loosening the rod 58 in the atomizer 60, whereby the outflow conditions can be changed. .

FIG. 7 shows an atomization system of the type described above, which is used here in connection with a portable spray gun 90. For this purpose, the power is controlled by means of a needle 91 which is actuated by a trigger 82, the needle 91 resting against a front seat 93 which is present in the ring body 51. As' seen here, the supply of the liquid 94 is arranged eccentrically and the central channel 95 is closed by a plug 96 which sealingly receives the needle 91. The compressed air supply consists of a pipe 97, which in

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a recess in the nozzle made of insulating material * is arranged body and in which the ring body 51 is also housed.

Figure 8 illustrates another embodiment of an atomizing nozzle according to the present invention, which differs from the previously described arrangement is that the diffuser 60 a frusto-conical exhaust ^ Cut 100 comprises that the same cone angle sawn Ψ sits as the inner wall 101 of the ring body 51, which is adjoined by a conical region 102 which interacts with the end portion of the surface 101 of the ring body which forms a valve seat. In this case, the annular outflow channel forms a liquid layer of constant thickness between the annular body 51 and the atomizer 60;

Regardless of the shape of the annular space used (parallel annular space or conical, converging or diverging annulus) the best results in terms of atomization are obtained when the end edge 104 of the Zerfc When the atomizer 60 is in the retracted position, it is immediately adjacent to the end edge 105 of the annular body 51 lies. If one deviates from this version, the received Results less good.

It is also important that the annular space which is located on the inflow side of the atomizing edge is as thin as. possible is trained. Too large a cavity leads to a reduction in atomization, which then becomes jerky and of poor quality. An upstream cavity

I.

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with small dimensions is shown in the two Design of the nozzle received:

In the embodiment according to FIG. 5, this is reduced Void obtained by adding a slight difference in taper between the ring body 51 and the atomizer 60 is maintained. It is advantageous that the angle formed by the inner surface of the ring body 51 and the outer surface of the atomizer 60 is formed, is smaller than 5 °.

In the embodiment according to FIG. 8, the inner wall of the ring body 51 and the outer wall of the atomizer 52 a small distance; it is important that this Distance is less than 0.5 mm.

Another measure that must be taken into account with such nozzles relates to the cone angle of the ring body 51 and of the atomizer 60. This angle can fluctuate between sufficiently large limit values, but it has been found that a suitable cone angle is about 40 °, the deviations being between + 20 °.

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Claims (1)

CAS 112 + 113 JL July 8th I97O Patent applications Atomizer nozzle for a system for spraying * arbe, Email or the like, with a first annular space for the delivery of the liquid material to be atomized and with a second, concentric and outside of the first-mentioned annular space, a second annular space for the atomizing air, wherein the first-mentioned annular space is formed by the interior of an annular body in which a central atomizer is arranged, which has an annular outlet channel for the liquid to be atomized Forms fabric, characterized in that the longitudinal dimension, the circumferential dimension and the thickness of the Annular channel of the atomizer nozzle are dimensioned such that for the area of the liquids to be atomized the occurring charge loss occurs in the immediate vicinity of the highest charge loss, which is either for the loss of charge is obtained, which is a limit value for the non-occurrence of a reduction in liquid or the formation of a stable layer, caused by surface tension. 2. Atomizer nozzle for a system for spraying paint, Email or the like according to claim 1, characterized in that the circumferential dimension of the discharge edge of the nozzle, measured in centimeters, is between 0.05 and 0.2. the value of the power to be atomized, measured in liters / hour. - 16 - 000885/1557 GAS 112 + 113. J (^ 3. Atomizer nozzle according to claim 2, characterized in that the ring space has a substantially constant thickness and that between said thickness and the Longitudinal dimension of the annulus is a ratio which is between 1/20 and 1/10 and preferably between 1/5 and 1/7 lies. 4. atomizer nozzle according to claim 2, characterized in that that the annular space in axial section a truncated cone-shaped *, against the outlet end to convergent exhaust · having-section and that the cone angle is smaller than 5 °. 5. Atomizer nozzle according to one of claims 1 to 4, characterized in that the annular space of the atomizer nozzle as Truncated cone is formed, which widens outwards. 6. Atomizer nozzle according to one of claims 1 to 4, characterized characterized in that the annular space of the nozzle is cylindrical. .... ' . <7 »Atomizer nozzle for the pneumatic atomization of a liquid substance, in particular for the application of a fine layer of paint, enamel or the like according to claim 1, characterized in that the central atomizer is arranged sliding axially in the ring body and by a return spring against a retracted position is pressed corresponding to a closure of the annular space, and the return spring exerts a balance between the pressure of the liquid on the said atomizer in such a way that the correct opening of the annular space is ensured. - 17 - ■ * 00 * 885/1557 12+ 113 θ. Atomizer nozzle according to claim 7 »characterized in that the sliding arrangement of the atomizer is a slight allows radial play. 9. atomizer nozzle according to claim 7, characterized in that the atomizer on an axially extending Rod is attached, which in turn is arranged in a sleeve which is in a rear region of the Annular body is attached. 10 .. Atomizer nozzle according to claims 7 to 9 »characterized in that that the axially extending rod that supports the atomizer is located in the sleeve and extends through an opening in a transverse wall of the sleeve, the diameter of the opening being appreciable larger than the outer diameter of the axially extending Rod is, and lateral and / or transverse channels through the sleeve allow the liquid to pass through allow. 11. Atomizer nozzle according to claims 7 »8 and 9, thereby characterized in that the atomizer is disposed on the axially extending rod which passes through the wall the sleeve slides while the return spring is against said wall of the sleeve and a shoulder of the rod lays. " 12. Atomizer nozzle according to claim 7, characterized in that, that the annular space and the atomizer are designed to widen outwardly in the shape of a truncated cone and that the cone angle of the atomizer is slightly larger than the cone angle of the ring body, ao that in the inlet position of the ring channel is completed. - 18 009885/1557 13 · Atomizer nozzle according to claim 7, characterized in that that the return spring of the atomizer is adjustable. · 14. Atomizer nozzle according to claims 7 and 9 »characterized in that the axially extending rod · adjustable is screwed into the atomizer. 15. Atomizer nozzle according to claim 7, characterized in that that the annular space between the annular body and the atomizer has a small capacity for the liquid. 16. Atomizer nozzle according to claim 12, characterized in that the angle of convergence of the annular space between the Ring body and the atomizer is smaller than 5 °. 17 · Atomizer nozzle according to claim 15, characterized in that that the ring body and the atomizer have the same cone angle and that the atomizer is frustoconical has formed end portion which forms a valve seat. 18. Atomizer nozzle according to claim 17, characterized in that I that the distance between the inner wall of the ring body and the outer wall of the atomizer is less than 0.5 mm is. 19 · Atomizer nozzle according to claim 7, characterized in that that the inner wall of the ring body and the outer wall of the Atomizer have a cone angle which is between 20 ° and 60 ° and preferably in the range of 40 °. - 19 - 009885/1557 20. Atomizer nozzle according to claims 7 to 19, characterized characterized in that an outlet channel in the ring body or in the end section of the supply line in the vicinity of the ring body is provided. 21. Atomizer nozzle according to claims 7 to .19, characterized by connecting it to a device for shutting off the supply of parboil liquid, namely a needle or pump, which cooperates with the fixed additional closure device, the is formed by the atomizer and the ring body. - 20 -001885/1657 Blank page