WO2015144867A1 - Method and device for producing a liquid spray - Google Patents

Abstract

The invention relates to a method and device for producing a liquid spray (N), comprising predetermined movement components, in which at least two focused liquid jets (S1, S2) which are angled with respect to each other, collide with each other at an impingement point (P) which is spatially separate from the jet nozzles (D1, D2). The distance (a) of the nozzle mouths (DM) and the angle of inclination (β) between the liquid jets (S1, S2) are co-ordinated with each other such that the nozzle mouths (DM) remain free of the generated liquid spray (N).

Description

METHOD AND DEVICE FOR PRODUCING LIQUID MIST

The invention relates to a method and apparatus for generating liquid mist with a predetermined component of movement, wherein at least two angularly aligned sharply focused liquid jets S ₁ , S ₂ in an impingement point P which is spatially away from the jet nozzles D ₁ , D ₂ , meet one another, in particular according to the preambles of claims 1 and 11.

The liquid mist N is commonly used for wetting or coating substrates. Particularly preferably, different types of liquids are to be mixed in an impact point or in the liquid mist, possibly in conjunction with other fluids, gases, low-viscosity liquids or the like. A method of the aforementioned type is known from DE 10 2012 204 426 A1. The method for spray coating an article with a hot melt adhesive described in this document teaches ejecting a molten hot melt adhesive through a first die and a second die such that a first melt stream exiting the first die and a second melt stream exiting the second die are sharpened Angle meet each other so that forms a Sprühfächer, wherein the nozzles are maintained at a predetermined target temperature. By maintaining the target temperature, a desired viscosity of the hot melt adhesive should be achieved to thereby maintain the desired droplet size of the spray fan. The angle of inclination of the melt jets should always be an acute angle between 10 ° and 80 °. About the distance of the nozzle orifices of the melt jets are given in the aforementioned document no information.

It has now been found that in the execution of the aforementioned method there is the danger that, especially when the spraying discontinuous, d. H. Thus, with interruptions, running, by uncontrolled backflow wetting of the nozzle orifices takes place through the generated liquid mist and thus there is a risk of contamination or clogging of the nozzles.

Object of the present invention is to improve the generic method and a device so that such a backflow and thus contamination of the nozzle orifices is excluded. At the same time, the user should be allowed to set a mixing ratio and the degree of mixing in the spray as a function of different liquids. Also, the wear of the nozzles over the useful life

are
a ₁ , a _{2 shows} the distances of the nozzle orifices DM of the jet nozzles D ₁ , D ₂ to the solder from the point of impact P on the connecting line V of the nozzle orifices DM of the jet nozzles D ₁ , D ₂ ,
b is the distance of the point of impact P from the connecting line V of the nozzle orifices DM and
β ₁ , β _2, the angle of inclination of the liquid jets S ₁ , S ₂ to the solder from the point of impact P on the connecting line V of the nozzle orifices DM,
Thus, the object is achieved according to the invention in that the distances a ₁ , a ₂ , the inclination angle β ₁ , β ₂ and the distance b are coordinated so that the nozzle orifices DM remain free from the generated liquid mist.

The coordination of the quantities a _n , β _n and b can be carried out empirically by experiments. Preferably and in a further embodiment of the invention, for example for generating a liquid mist N from two liquid jets S ₁ and S ₂ , the distance a of the nozzle orifices DM according to the formula a = b * (tan β ₁ + tan β ₂ ), where a = a ₁ + a ₂ and β = β ₁ + β ₂ are adjusted. In this coordination of the sizes a, b and β wetting of the nozzles by the generated liquid mist can be reliably avoided if experience shows that the distance b is greater than 10 mm, even if the inclination angle β = β ₁ + β ₂ between the Liquid jets have an angle ≥ 80 °.

For a particularly intensive nebulization of the liquid jets angle of inclination β of more than 80 ° in particular obtuse angles are desirable. In a further embodiment of the invention is therefore proposed that the inclination angle β of the liquid jets S ₁ , S _{2 is} between 30 ° and 120 °. Especially the range of larger angles of inclination between 80 ° and 120 ° brings, as far as the nebulization, particularly good results in terms of achievable small droplet size of the liquid.

Depending on the viscosity of the liquid to be atomized in another embodiment of the invention, the liquid pressure in the nozzle and the nozzle orifice cross-section should be coordinated so that a jet velocity v at the nozzle orifice of 15 - 150 m / sec. results. In this case, it is preferable to set the jet velocity, starting from a low value and a low viscosity of the liquid to be atomized, proportionally to the viscosity of the atomized liquid.

Particularly advantageous results can be achieved if at a viscosity of the liquid of 400 mPa ^. s (milli-pascal second) an exit velocity of 150 m / sec. is set.

The number of liquid jets, which can be made to produce directional liquid mist N at the point of impact P, can be more than two, as already indicated above by the phrase "at least two".

In an advantageous embodiment of the method, in which at least two, preferably three, liquid jets meet at the point of impact P, at least one of the liquid jets should be controllable with respect to the direction and / or the jet velocity. As a result, both the shape and the direction of movement of the generated spray fan or the liquid mist N can be adjusted. In the case of different liquids, it is thus also possible to control or adjust the mixture pattern and / or the mixing ratio.

In a further embodiment of the method according to the invention, it is provided that, in addition to the liquid jets S ₁ ... S _n, a gas jet GS is directed onto the point of impact P. Depending on the liquid used, in particular on the viscosity of the liquid used, the atomization can be improved by the use of an additional gas jet GS. In addition, the use of an additional gas jet GS creates the possibility of finely distributing substance components, for example glue for glue, which is mixed with the gas jet GS into the liquid mist N, which can bring advantages depending on the use or environment of the liquid mist.

Finally, it should be provided in a further embodiment of the method that the liquid jets S ₁ ... S _n consist of different liquids. In this case, not only a generation of liquid mist N is achieved from a liquid, but in addition also an intensive mixing of the liquids used.

Furthermore, the invention relates to a device, in particular for carrying out the method, with at least two spaced apart on a nozzle carrier DT arranged jet nozzles D ₁ , D ₂ , which are adapted so that they produce bundled liquid jets S ₁ , S ₂ and the are aligned at an angle to each other, that the liquid jets S ₁ , S ₂ meet at a point of impact P on each other. Such a device is again known from the above-mentioned document DE 10 2012 204 426 A1, FIG. 2 and associated description.

As already stated above in connection with the description of the method according to the invention, it is an object of the present invention to improve such a device so that on the one hand high-grade atomization of the liquid used takes place, on the other hand wetting or contamination of the nozzle openings is avoided with certainty.

According to the invention, the distances a ₁ , a _{2 of} the nozzle mouths DM of the jet nozzles D ₁ , D ₂ to the solder from the impact point P on the connecting line V of the nozzle orifices DM, and the inclination angle β ₁ , β _{2 of} the liquid jets S _1, S ₂ to the solder from the point of impact P on the connecting line V of Nozzle mouths DM be coordinated with each other so that the point of impact P is located at such a distance from the nozzle orifices that they remain free from the liquid mist N generated when the liquid jets S ₁ , S ₂ meet. In an advantageous embodiment of this teaching, for example for generating a liquid mist N from two liquid jets S ₁ and S _2, the distance of the nozzle orifices DM a = b * (tan β ₁ + tan β ₂ ), where a = a ₁ + a ₂ and β = β ₁ + β ₂ , b is the distance of the point of impact P from the connecting line V of the nozzle orifices DM and β ₁ , β _{2 are} the angles of inclination of the liquid jets S ₁ , S ₂ to the solder from the point of impact P on the connecting line V of the nozzle orifices DM. It has been shown that, while maintaining this dependence between the sizes a, b and β excellent fogging results can be achieved while avoiding any wetting of the nozzle orifices.

A further embodiment undergoes the device according to the invention in that a plurality of jet nozzles D ₁ - D _n , preferably regularly and / or annularly distributed on the nozzle carrier DT are arranged so that all exiting liquid jets lie on the mantle of a cone whose tip is the point of impact P. In such an embodiment, the angles of inclination β ₁ ... Β _{n of} the liquid jets S ₁ ... S _n to the perpendicular from the point of impact P to the nozzle plane, which are defined by the nozzle orifices DM, are preferably between 15 ° and 60 °.

In an arrangement of a plurality of jet nozzles D _n , the liquid jet S _n with the same inclination angle β ₁ = β ₂ = ... = β _n generate, the opening angle of the cone is 2 x β ₁ and should preferably be between 30 ° and 120 °. The advantage of an arrangement with several jet nozzles is that higher quantities of liquid can be atomized and a uniform, preferably circular and / or cone-shaped spray fan is obtained.

In an advantageous embodiment of the device according to the invention, at least one of the jet nozzles D ₁ - D _n on the nozzle carrier DT is to be arranged variable in their position and / or their orientation. By such a design, the orientation or the shape of the generated liquid mist N can be selected depending on the setting of the variable nozzle DV.

In addition, it is possible to switch the liquid jet discontinuously in the case of individual or all jet nozzles DV and thus to obtain a differently shaped liquid mist N over time. In particular, it may be advantageous to use pulsed nozzles, whereby it can then arrive again on the substrate to be sprayed.

In a further embodiment of the device according to the invention, it is proposed that, in addition to the jet nozzles D ₁ - D _n, a gas nozzle DG suitable for a gaseous fluid be provided for liquids. Depending on the type of liquid used, such a design can help to make the nebulization more effective and with even finer droplet size. The arrangement of the gas nozzle DG for gaseous fluid is preferably selected centrally with respect to the arranged jet nozzles D ₁ ... D _n for liquids. In this case, the gas nozzle DG has the smallest distance b to the impact point P.

A further possibility would be to arrange one of the nozzles D ₁ -D _n for liquids centrally with respect to the other jet nozzles D ₁ -D _{n in} order to meter an additional liquid, preferably discontinuously, without influencing the liquid mist N in its direction and extent. The device can be operated independently, but is preferably suitable for carrying out the method. The person skilled in the art will, within its capabilities, use known control and regulation mechanisms (valves, measuring instruments, flow meters, control and / or regulating means) in order to achieve or optimize the result to be achieved.

In a particularly advantageous manner, the method and apparatus in the course of the production of material plates can be used, in which case the adhesive liquor (glue, hardener, aggregates ...) is sprayed onto the still loose material (chips, fibers, nonwoven ....) With these nozzles , Advantageously, in particular the glue (isocyanate or the like) is mixed with a hardener prior to impact with the loose material, usually in a chute or a mixer, and in each case proportionately sprayed onto the material. Advantageously, the degree of mixing and the impact with the invention can be adapted to the circumstances.

Reference to the accompanying drawings, the inventive method and the apparatus for performing the method are exemplified. In the drawings shows:
1 is a basic schematic representation of the method for generating liquid mist N from two liquid jets S ₁ , S ₂ ,
FIG. 2 shows a first embodiment of a device for carrying out the method as shown in FIG. 1, FIG.
3 shows an alternative embodiment of a device according to FIG. 2 with a positionally variable alignment nozzle DV, FIG.
Fig. 4 shows a further alternative embodiment of the device according to Fig. 2 with a central gas nozzle DG and
Fig. 5 is a plan view against the nozzle carrier DT in the direction of jet nozzle mouths DM on a device according to FIG. 2, however, with three jet nozzles.

For a better understanding, the distances a, b and angle β according to the invention are once again defined. The distance a defines the distance between the nozzle orifices DM. A _{1 is the} distance of the nozzle orifice DM from the nozzle D ₁ to the solder from the point of impact P on the connecting line V. Accordingly, a _{2 is} the distance of the nozzle orifice DM of the nozzle D ₂ to the solder of Impact point P on the connecting line V. In general, with a plurality of nozzles, the distance a _{n of} the nozzle mouth DM of the nozzle D _n to the solder from the impact point P on the connecting line V. b defined the distance of the connecting line V to the impact point P. The angle β shows the tilt angle between the liquid jets S ₁ - S _{2, 1} β the angle of inclination of the liquid jet _S1 to the perpendicular from the impact point P on the connecting line V, β _{2 is} the angle of inclination of the liquid jet S ₂ to the vertical corresponding to the impact point P on the connecting line V and for several angle β _n the angle of inclination of the liquid jet S _n to the solder from the point of impact P on the connecting line V.

In the schematic representation according to FIG. 1, two jet nozzles D ₁ and D ₂ arranged at a distance from one another are shown, from which bundled liquid jets S ₁ , S ₂ can emerge. The direction of the liquid jets S ₁ , S ₂ is indicated by vectors. The vectors are not true to scale, but partly serve in their different length in the figures as an indication of different jet velocities v. The pressure necessary for the production of the bundled liquid jets S ₁ , S ₂ is established in a conventional manner above the nozzle orifices, which is not shown in detail. The jet nozzles D ₁ and D ₂ are arranged so that their nozzle orifices DM have a distance of a. Furthermore, the jet nozzles D ₁ , D ₂ are aligned so that the exiting liquid jets S ₁ , S ₂ against each other assume an inclination angle β = β ₁ + β ₂ and the two liquid jets S ₁ , S ₂ in one point, namely the point of impact P, meet each other. When the liquid jets S ₁ , S ₂ meet at the point of impact P, they are atomized in very fine droplets to form a liquid mist N. The liquid mist N extends substantially within the angle of the downwardly continued beam directions S ₁ , S ₂ . However, a certain uncontrolled backflow in the direction of the jet nozzles D ₁ , D ₂ can not be prevented by the meeting of the two bundled liquid jets S ₁ , S ₂ . Thus, this return flow of liquid fog does not reach the nozzle orifices, the arrangement being such that the distances a _1, a ₂ of the nozzle orifices DM of the jet nozzles D _1, D ₂ on the connecting line V of the nozzle orifices DM and the inclination angle β to the perpendicular from the impingement point P ₁ , β _{2 of} the liquid jets S ₁ , S ₂ to the solder from the point of impact P on the connecting line V of the nozzle orifices DM via the relationship a = b * (tan β ₁ + tan β ₂ ), where a = a ₁ + a ₂ and β = β ₁ + β ₂ , should be chosen so that the distance b of the point of impact P from the connecting line V of the nozzle orifices DM is greater than 10 mm.

If one were to choose a smaller angle of inclination β for the two liquid jets S ₁ , S ₂ than that shown in FIG. 1, then, according to the abovementioned dependence between the angle of inclination β and the distance a, a larger possible distance b of the point of collision P would result to the connecting line V. Conversely, at a certain angle of inclination β the distance a should be greater according to the formula shown to obtain a distance b greater than 10 mm and so a backflow from the liquid mist N to the nozzle orifices DM of the jet nozzles D ₁ , D. ₂ sure to avoid. By changing the above formula, a desired limit of the distance b depending on the distance a = a ₁ + a ₂ and the inclination angle β = β ₁ + β ₂ can be determined: b = a / (tan β ₁ + tan β ₂ ). At a fixed distance a = 30 mm, an inclination angle β = 90 ° leads to a distance b = 15 mm. At an inclination angle β = 115 ° to a distance b = 9.55 mm.

For the apparatus shown schematically in Fig. 2, the same reference numerals as in Fig. 1 are selected. The device comprises a substantially cylindrical nozzle carrier DT whose central axis is denoted by TM. At the nozzle carrier DT jet nozzles D ₁ and D ₂ are arranged in such a way that the exiting bundled liquid jets S ₁ , S ₂ meet again in the point of impact P at an angle β of substantially 90 °. The resulting liquid mist is denoted by N.

The embodiment shown in Fig. 3 of a device according to the invention is shown in a view as it corresponds to FIG. 2. One of the jet nozzles D _n , which is denoted by DV in the figure, should be changeable in its position and its orientation, which is indicated in Fig. 3, that the nozzle orifice DM is located eccentrically to the nozzle main axis H of the nozzle DV. Thus, by means of an eccentric rotation of the nozzles, the vector of the liquid jet and thus the position of the point of impact could be changed. Respectively, the appearance of the liquid mist N then also changes.

Alternatively or in combination, the nozzle can be pivoted, which is shown with a pivoting range W as a bow arrow on the nozzle DV. Alternatively or in combination, the nozzle DV along a linear movement X can be moved to adjust the impact point P accordingly.

Corresponding to the asymmetrically positioned nozzle DV and, consequently, the changed position of the liquid jet emerging from the nozzle DV, an asymmetrically formed liquid mist N results, both as regards the shape and its position in space. The setting of the variable nozzle DV takes place depending on the desired position and shape of the liquid mist N. The arrangement of a variable nozzle DV is possible in combination with one or more other nozzles D _N (eg in FIG. 5). In the case of different liquids, it would then be in the advantageous position nevertheless to form a symmetrical liquid mist N and thus, in particular with a large number of devices next to one another, to generate a large-area spray pattern with adjacent and / or overlapping spraying cones. Also occurring with the help of adjustable jet nozzles DV wear or other occurring during production changes to the devices can be compensated and a uniform possible spraying over time to be ensured.

It would accordingly be possible, in adaptation to the local conditions, to provide a nozzle carrier DT in which different angles β _{n of} the jet nozzles D _{n are} provided, which are adapted to the corresponding liquids in order to obtain optimum liquid mist N.

In the further embodiment of an inventive device according to FIG. 4 in addition to the liquid jet nozzle D nor _n a central gas nozzle DG arranged, the gas jet GS also on the impact point P of the liquid jets S _n from the jet nozzles D _n is addressed. Depending on the viscosity of the liquid used, the use of a, in particular central, gas jet GS can once again increase or at least adapt the fogging quality. It may also be useful in the course of atomization to increase the energy content of the individual components in the liquid mist N, for example with steam, in particular in order to improve the mixing itself.

In the embodiment according to FIG. 5, with the view from below against the nozzle carrier, a total of three jet nozzles (denoted by D _n in FIG. 5) are provided, which are regularly distributed on a circular ring, so that the angular distance from a nozzle D _n until the next 120 °.

List of Reference Numerals: P1475
a distance
a ₁ distance
a ₂ distance
a distance _n
b distance
β inclination angle
β ₁ inclination angle
β ₂ inclination angle
β _n angle of inclination
D ₁ nozzle
D ₂ nozzle
D _n n-th nozzle
DG gas nozzle
DM nozzle mouth
DT nozzle holder
DV nozzle
GS gas jet
H main axis
N liquid mist
P point of impact
S ₁ liquid jet
S ₂ liquid jet
S _n liquid jet
TM longitudinal axis
V connecting line
v jet velocity
W swivel range
X linear motion

Claims (17)

1. A method for generating liquid mist (N) with a predetermined component of motion, wherein at least two angularly aligned, focused liquid jets (S ₁ , S ₂ ) in an impingement point (P), which spatially from the jet nozzles (D ₁ , D ₂ ) is, meet one another, characterized in that the distance (a) of the nozzle orifices (DM) and the inclination angle (β) between the liquid jets (S ₁ , S ₂ ) are coordinated so that the nozzle orifices (DM) from the generated liquid mist (N) stay free.
2. A method according to claim 1, characterized in that the distance (a) of the nozzle orifices (DM) according to the formula a = b * (tan β ₁ + tan β ₂ ) is set, where a = a ₁ + a ₂ and a ₁ and a _2, the distances of the nozzle orifices (DM) of the jet nozzles (D ₁ , D ₂ ) to the solder from the point of impact (P) on the connecting line (V) of the nozzle orifices (DM) of the jet nozzles (D ₁ , D ₂ ), wherein the angle of inclination β = β ₁ + β ₂ and β ₁ and β _{2 is} the inclination angle of the liquid jets (S ₁ , S ₂ ) to the solder from the point of impact (P) on the connecting line (V) of the nozzle orifices (DM) and wherein (b) is the distance of the four-bond line (V) to the point of impact (P).
3. A method according to claim 1 or claim 2, characterized in that the angle of inclination (β) is between 30 ° and 120 °.
4. Method according to one or more of claims 1 to 3, characterized in that the distance (b) of the connecting line (V) of the nozzle orifices (DM) from the point of impact (P) is preferably greater than 10 mm.
5. Method according to one or more of claims 1 to 4, characterized in that the liquid pressure in the nozzles (D ₁ , D ₂ ) and the nozzle orifice cross-section are coordinated so that a jet velocity (v) at the nozzle orifice (DM) of 15 - 150 m / sec. results.
6. Method according to one or more of claims 1 to 5, characterized in that the jet velocity (v) is adjusted in proportion to the viscosity of the liquid to be atomized.
7. Method according to one or more of claims 1 to 6, characterized in that at a viscosity of the liquid of 400 mPa ^. s an exit velocity of 150 m / sec. is set.
8. Method according to one or more of claims 1 to 7, characterized in that at least two, preferably three liquid jets (S ₁ - S _n) can take in the impact point (P) to one another, of which at least one (in direction and / or jet velocity v ) is controllable.
9. Method according to one or more of claims 1 to 8, characterized in that in addition to the liquid jets (S ₁ - S _n ) directs a gas jet (GS) to the point of impact (P).
10. Method according to one or more of claims 1 to 9, characterized in that the liquid jets (S ₁ -S _n ) consist of different liquids.
11. Method according to one or more of claims 1 to 10, characterized in that at least two liquid jets (S ₁ , S ₂ ) contain different components of an adhesive liquor, in particular glue and an associated hardener.
12. Device, in particular for carrying out the method according to one or more of Claims 1 to 11, having at least two jet nozzles (D ₁ , D ₂ ) arranged at a nozzle carrier (DT) spaced apart from one another and adapted to bundle liquid jets (S ₁ , S ₂ ) and are aligned at an angle to each other, that the liquid jets (S ₁ , S ₂ ) meet at an impact point (P), characterized in that the distance (a) of the nozzle orifices (DM) from each other and the inclination angle (β) between the liquid jets (S ₁ , S ₂ ) are matched to one another such that the point of impact (P) at such a distance from the nozzle orifices (DM), that this from the liquid mist generated at the meeting of the liquid jets (N) free stay.
13. Apparatus according to claim 12, characterized in that the distance (a) of the nozzle orifices (DM) according to the formula a = b * (tan β ₁ + tan β ₂ ) is set, where a = a ₁ + a ₂ and a ₁ and a _2, the distances of the nozzle orifices (DM) of the jet nozzles (D ₁ , D ₂ ) to the solder from the point of impact (P) on the connecting line (V) of the nozzle orifices (DM) of the jet nozzles (D ₁ , D ₂ ), wherein the angle of inclination β = β ₁ + β ₂ and β ₁ and β _{2 is} the inclination angle of the liquid jets (S ₁ , S ₂ ) to the solder from the point of impact (P) on the connecting line (V) of the nozzle orifices (DM) and wherein (b) the distance of the connecting line (V) to the point of impact (P).
14. Device according to claims 12 or 13, characterized in that a plurality of jet nozzles (D ₁ - D _n ), in particular regularly and / or annularly distributed on the nozzle carrier (DT) are arranged so that all the exiting liquid jets (S ₁ - S _n ) lie on the mantle of a cone whose tip is the point of collision (P).
15. Apparatus according to claim 14, characterized in that the opening angle of the cone is between 30 ° and 120 °.
16. Device according to one or more of claims 12 to 15, characterized in that at least one of the jet nozzles (D ₁ - D _n ) on the nozzle carrier (DT) is arranged variable in their position and / or their orientation.
17. Device according to one or more of claims 12 to 16, characterized in that in addition to the liquid nozzles (S ₁ -S _n ), a gas nozzle (DG) adapted for a gaseous fluid is provided.

Images