Method for discharging a liquid using a nozzle device

Abstract

The invention relates to a method for discharging a liquid using a nozzle device (DV). The nozzle device (DV) has a nozzle head (DUK) and a nozzle body (DKO), and the nozzle head (DUK) has a liquid outlet opening (FLO) and at least one air outlet opening (LUO) arranged at a distance from the liquid outlet opening (FLO) in a lateral direction. In a first step, only a liquid jet (FST) is dispensed through the liquid outlet opening (FLO), and in a second step, an air flow (LUF) is dispensed through the air outlet opening (LUO) while the liquid jet is being dispensed, wherein the air flow (LUF) strikes the liquid jet (FST) at a distance after exiting the liquid outlet opening (FLO), and the liquid jet (FST) is fanned out by the air flow (LUF).

Description

[0001] The invention relates to a method for dispensing a liquid by means of a nozzle device.

[0002] Such nozzle devices are used, for example, in the automotive industry, where a liquid, preferably a weld sealant, is applied. The nozzle device is mounted on a lance, which is designed as a robot arm. A key requirement in the automotive industry is that the application is quick and reliable.

[0003] A device for coating an object with a medium is known from DE 10 2010 056263 A1. Such a device has an outlet opening from which the medium emerges, which is atomized by means of compressed air from atomizing nozzles into a spray jet with a jet profile. Furthermore, the known device has at least two pairs of stationary jet-shaping units, each diametrically opposed with respect to the outlet opening, which direct compressed air onto the spray jet via at least one shaping fluid opening, whereby the spray jet is shaped by each pair of jet-shaping units into a fan-shaped flat jet with a substantially strip-shaped jet profile. If two pairs of jet-shaping units are used, the two diametrically opposed pairs are arranged offset by 90°.By alternately switching on the two pairs of jet shaping units, the spray jet can be transformed into two fan-shaped flat jets that are twisted perpendicular to each other.

[0004] Such known devices are used in the automotive industry in the form of spray guns for the automated painting of vehicle bodies or vehicle parts.

[0005] Furthermore, DE 966 200 C discloses a manually operated paint spray gun with pneumatic paint valve control using two finger triggers. A first finger trigger opens the paint valve, allowing compressed air to flow simultaneously from atomizing nozzles to form a spray jet, thus preventing droplet formation before and after the paint nozzle is opened. The second finger trigger directs compressed air through two molding fluid openings onto the spray jet to regulate its flat jet width. The two molding fluid openings are arranged diametrically opposite the spray jet outlet.

[0006] Such spray guns are designed to suppress paint or liquid jet modes in order not to endanger a painting process.

[0007] Against this background, the object of the invention is to provide a method that further develops the state of the art.

[0008] The object is achieved by a method for dispensing a liquid by means of a nozzle device having the features of patent claim 1. Advantageous embodiments of the invention are the subject of subclaims.

[0009] According to the subject matter of the invention, a method for dispensing a liquid by means of a nozzle device is provided, wherein the nozzle device has a nozzle head and a nozzle body.

[0010] The nozzle head has a liquid outlet opening and at least one air outlet opening laterally spaced from the liquid outlet opening.

[0011] In a first process step, only a liquid jet of constant diameter is discharged through the liquid outlet opening up to a distance of between 0.5 m and 2 m from the nozzle device. In other words, no air flow is discharged through the air outlet opening in the first process step.

[0012] In a second process step, an air stream is discharged through the air outlet opening while the liquid jet is being discharged.

[0013] The air stream hits the liquid jet at a distance after it exits the liquid outlet opening.

[0014] The liquid jet is fanned out by the air stream. In a further development, the liquid jet is fanned out exclusively by the air stream.

[0015] In other words, the liquid jet is, in a first approximation, formed as a jet without air flow even at a distance from the nozzle device between 0.5 m and 2 m.

[0016] It should be noted that the nozzle head and the nozzle body are preferably formed as a single piece. In an alternative embodiment, the nozzle head and the nozzle body are formed as two pieces.

[0017] In a further development, the air outlet opening and the liquid outlet opening are each round.

[0018] Preferably, the nozzle head has a truncated cone shape and the nozzle body has a cylindrical shape.

[0019] In a further development, the nozzle device has a diameter between 6 mm and 20 mm or between 8 mm and 14 mm or is 10 mm.

[0020] In another embodiment, the length of the nozzle device is in a range between 10 mm and 30 mm or between 15 mm and 25 mm or is 20 mm.

[0021] In one embodiment, the liquid outlet opening is arranged centrally, while the air outlet opening is formed laterally spaced on the lateral surface of the nozzle head.

[0022] Preferably, the nozzle head and the nozzle body are made of a metal or an alloy. In one embodiment, the air outlet opening is round.

[0023] One advantage of the process is that it allows for easy switching between a spray jet in the first process step and a spray jet in the second process step. In other words, to create a spray jet, an air stream is simply discharged through the air outlet opening, and vice versa. This allows switching between a spray jet and a spray jet at any time, even during use of the process.

[0024] Cleaning the nozzle device is also eliminated when switching between the two process steps. Because the air only hits the liquid jet at a distance from the nozzle outlet opening, and the flow direction of the escaping air is preferably laminar and in the direction of the liquid jet, no turbulence occurs even when the air flow is switched on. This prevents liquid droplets from flying toward the nozzle head. Contamination of the nozzle outlet opening is avoided. In other words, even after numerous back-and-forth switching between the two process steps, contamination, particularly of the nozzle head, can be avoided.

[0025] In a further development, switching between the two process steps can be performed instantaneously. In other words, the switching between the two process steps can be performed without any time delay. One advantage is that switching between the first and second process steps can be performed as often as required during the application of the liquid.

[0026] In one embodiment, a first switching device and a second switching device are provided, wherein the first switching device switches the liquid jet on and off, and the second switching device switches the air flow on and off. In other words, to switch between the two process steps, the air flow is switched on or off.

[0027] In a further development, the air flow is only switched on or off when the liquid jet is switched on.

[0028] In one embodiment, the air outlet opening is round. In another embodiment, the diameter of the air outlet opening is in a range between 0.2 mm and 0.6 mm. Preferably, the diameter of the air outlet opening is 0.4 mm.

[0029] In another development, a plurality of air outlet openings are provided around the liquid outlet opening, wherein in the second method step the air flow is discharged simultaneously through the plurality of air outlet openings, so that the liquid jet is hit by the air flow from several sides.

[0030] In one embodiment, the multiple air streams meet the liquid jet at the same distance, i.e. the air streams meet at a "focal point".

[0031] In one embodiment, each air outlet opening within the nozzle device has a separate air supply in the form of a round supply duct. The diameter of the supply duct preferably corresponds to the diameter of the air outlet opening.

[0032] In a further development, all air outlet openings have the same diameter.

[0033] In one embodiment, between three and a maximum of fifteen or exactly six air outlet openings are provided, wherein the air outlet openings are preferably arranged symmetrically around the liquid outlet opening, so that the liquid jet in the second method step is hit by each air stream passing through the respective air outlet openings at the same distance.

[0034] In one embodiment, the diameter of the liquid outlet opening is in a range between 0.1 mm to 1 mm or in a range between 0.1 mm and 0.5 mm or preferably the diameter of the liquid outlet opening is 0.2 mm.

[0035] In another embodiment, a pressure between 5 bar and 160 bar or between 10 bar and 120 bar or a pressure of 70 bar is applied to generate the liquid jet.

[0036] In another embodiment, the size of the air outlet opening is between 0.2 mm and 0.8 mm or between 0.3 mm and 0.6 mm or is 0.4 mm.

[0037] In a further development, a pressure between 0.1 bar and 12 bar or between 0.2 bar and 15 bar or between 0.2 bar and 5 bar or a pressure of 0.4 bar is applied to generate the air flow.

[0038] In a further development, the opening angle of the intersection point between the air flow and the liquid jet in the direction of the nozzle head is in a range between 0.5° and 45° or in a range between 5° and 15° or at 10°.

[0039] In another embodiment, the distance between the nozzle head and the point where the air jet hits the liquid jet is in a range between 0.5 cm and 30 cm or in a range between 0.5 cm and 15 cm or in a range between 1.0 cm and 10 cm or 7 cm.

[0040] In another embodiment, the method is carried out at room temperature. The liquid jet is preferably at room temperature.

[0041] In one embodiment, a corrosion inhibitor is used as the liquid.

[0042] In one embodiment, a laminar air flow or a turbulent air flow is generated by changing the pressure of the air flow.

[0043] In other words, the liquid jet and the air flow are preferably laminar at or shortly after the respective outlet opening.

[0044] In a further development, the liquid jet is fanned out into a cone shape by means of the air flow and becomes a spray jet.

[0045] In another development, the fan-out has an opening angle between 2° and 45°.

[0046] In one embodiment, the method is used in particular to seal seams in metallic body parts.

[0047] The invention will be explained in more detail below with reference to the drawings. Similar parts are labeled with identical designations. The illustrated embodiments are schematic, ie the distances and the lateral and vertical extensions are not to scale and, unless otherwise stated, do not have any deducible geometric relationships to one another. Figure 1 shows a view of a liquid jet according to the first method step and a spray jet according to the second method step, and Figure 2 shows a cross-sectional view of a nozzle device according to the invention.

[0048] The illustration of the Figure 1shows a view of a nozzle device DV with a lance section. In a first method step V1, a liquid jet FST is discharged by means of the nozzle device DV. The liquid jet FST has a nearly constant diameter, ie, it is laminar.

[0049] In the second process step V2, an air stream LUF is emitted during the discharge of the liquid jet FST. By emitting the air stream LUF, which impinges on the liquid jet FST at a distance D1, the liquid jet FST is fanned out into a spray jet SPT.

[0050] In the illustration of the Figure 2 shows a cross-sectional view of the nozzle device DV, shown in conjunction with the figure of the Figure 1 . In the following, only the differences to those related to the Figure 1 explained characteristics.

[0051] The nozzle device DV comprises a nozzle head DUK and a nozzle body DKO. The nozzle head DUK is essentially shaped like a truncated cone. The nozzle body DKO is cylindrical. Preferably, the nozzle device DV has a length L of 20 mm and a diameter of 10 mm.

[0052] The nozzle device DV is formed in one piece from a metal. The liquid outlet opening FLO is located in the center, i.e., centrally, on the nozzle head DUK. The air outlet openings LUO are laterally spaced from the liquid outlet opening FLO on the outer surface of the nozzle head DUK. Each air outlet opening LUO has its own air channel LUK. The liquid outlet opening FLO has a cylindrical storage chamber VK in the center of the nozzle device.

Claims

1. Method of discharging a liquid by means of a nozzle device (DV), wherein the nozzle device (DV) comprises a nozzle head (DUK) and a nozzle body (DKO) and the nozzle head (DUK) has at least one liquid outlet opening (FLO) and at least one air outlet opening (LUO) laterally spaced from the liquid outlet opening (FLO), wherein - in a first method step (V1) only a liquid jet (FST) with a constant diameter is discharged through the liquid outlet opening (FLO) up to a distance from the nozzle device (DV) of between 0.5 m and 2 m, and - in a second method step (V2) during issue of the liquid jet (FST) an air flow (LUF) is issued through the air outlet opening (LUO), wherein the air flow (LUF) impinges on the liquid jet (FST) at a distance after issue from the liquid outlet opening (FLO) and the liquid jet (FST) is fanned out by means of the air flow (LUF).

2. Method of discharging a liquid according to claim 1, characterised in that switching over between the two method steps (V1, V2) can be undertaken instantaneously.

3. Method of discharging a liquid according to claim 1 or claim 2, characterised in that a first switching device and a second switching device are provided, the liquid jet (FST) being switched on and off by means of the first switching device and the air flow (LUF) being switched on and off by means of the second switching device.

4. Method of discharging a liquid according to any one of the preceding claims, characterised in that a plurality of air outlet openings (LUO) arranged around the liquid outlet opening (FLO) is provided and in the second method step (V2) the air flow (LUF) is issued simultaneously through the air outlet openings (LUO) of the plurality so that impingement on the liquid jet (FST) takes place at a plurality of sides.

5. Method of discharging a liquid according to any one of the preceding claims, characterised in that between three and at most fifteen, or exactly six, air outlet openings (LUO) are provided, wherein the air outlet openings (LUO) are arranged symmetrically about the liquid outlet opening (FLO) so that in the second method step (V2) impingement on the liquid jet (FST) by each air flow (LUF) takes place at the same distance.

6. Method of discharging a liquid according to any one of the preceding claims, characterised in that a pressure between 5 bars and 160 bars or between 10 bars and 120 bars or a pressure of 70 bars is applied for producing the liquid jet (FST).

7. Method of discharging a liquid according to any one of the preceding claims, characterised in that a pressure between 0.1 bars and 12 bars or between 0.2 bars and 5 bars or a pressure of 0.4 bars is applied for producing the air flow (LUF).

8. Method of discharging a liquid according to any one of the preceding claims, characterised in that the liquid jet (FST) has room temperature and an anti-corrosion agent is used as liquid.

9. Method of discharging a liquid according to any one of the preceding claims, characterised in that a laminar liquid jet (FST) is produced by means of the liquid outlet opening (FSO).

10. Method of discharging a liquid according to any one of the preceding claims, characterised in that a laminar air flow (LUF) or a turbulent air flow is produced by means of a change in the pressure of the air flow (LUF).

11. Method of discharging a liquid according to any one of the preceding claims, characterised in that the liquid jet (FST) is fanned out conically by means of the air flow (LUF).

12. Method of discharging a liquid according to any one of the preceding claims, characterised in that the fanning-out has an opening angle of between 2° and 45°.

13. Method of discharging a liquid according to any one of the preceding claims, characterised in that the air flow (LUF) is switched on or off only when the liquid jet (FST) is switched on.

14. Method of discharging a liquid according to any one of the preceding claims, characterised in that the opening angle of the intersection between the air flow (LUF) and the liquid jet (FST) in direction towards the nozzle head (DKO) lies in a region in a range between 5° and 15°.

15. Use of the method according to any one of the preceding claims for the sealing of seams in metallic bodywork parts.

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