DE102011079982A1 - Spray head for use in spray device for mixing and spraying polyurethane to manufacture polyurethane skin component, has spraying channel into which cleaning agent i.e. gas, is introduced via hole and feed channel in rest position of piston - Google Patents

Abstract

The head (1) has a spray unit (7) in which a spraying channel (8) is formed. Mixed plastic components e.g. polyol and isocyanate, are supplied to an outlet opening (14). An adjusting piston (3) comprises a feed channel (16) led into a mixing chamber in an operational position of the piston so that gas jet is introduced via an inlet hole (9) and introduced with the plastic components from the feed channel into the mixing chamber. Cleaning agent i.e. gas, is introduced into the channel via another inlet hole (10) and the feed channel in a rest position of the piston. An independent claim is also included for a spray device.

Description

Field of the invention

The invention relates to a spray head ( 1 for mixing and spraying reactive plastics (which serve, for example, by spraying workpieces to produce polyurethane skin components) according to the preamble of claim 1.

State of the art

Conventionally, in devices for spraying plastics such as polyurethane, two or more components are used, which are mixed together in a mixing chamber. For this purpose, these components of two channels are introduced into the mixing chamber, where they mix in the meeting and then brought from there in the mutually mixed condition via a channel to a spraying device, with which the mixed plastic is sprayed.

Such mixing devices are for example in the WO 2008/122400 A1 or the DE 11 2005 000 794 T5 described. The problem here are overspray in the spray pattern, Austragsleistungsverteilung, variance, discharge per wetted surface, as well as an increasingly building impurity in the spray unit.

Presentation of the invention

Object of the present invention is to provide a spray head of the type mentioned, which reduces the disadvantages presented above.

This object is achieved by a spray head according to claim 1. Particularly preferred developments of the invention are specified in the dependent claims.

The spray head according to the invention is characterized in that the actuating piston has a supply channel, which opens into the mixing chamber in the operating position of the actuating piston, so that a gas jet, which is introduced via a first inlet bore from the supply channel simultaneously with the components of the plastic in the mixing chamber can be introduced, and in the rest position of the actuating piston, a cleaning agent via a second inlet bore via the supply channel into the spray channel can be introduced.

On the one hand, this additional gas jet ensures additional turbulence of the raw materials to be mixed in the mixing chamber and thus intensifies the mixing; on the other hand, the additional gas jet leads to a tearing of the raw material mixture into fine droplets. This can be influenced by variance of the gas volume and / or the component mixture volume and / or the ratio of gas volume and component mixture volume, the droplet size and speed and thus the spray pattern of the component mixture can be optimally adjusted. In particular, for example, "overspray" reduced, discharge power distribution, variance can be improved. Furthermore, the coaxial introduction of the gas jet avoids or reduces an increasingly build-up of contamination in the spray unit. Furthermore, the spray head can be easily maintained by the possibility of integrated supply of a cleaning agent.

Preferably, the direction of the gas jet is aligned in the mixing chamber on the spray channel, preferably in a coaxial configuration of gas jet and spray channel.

In this way, undesired vortices or dead spaces in the spray channel can be prevented, the contamination of the spray channel can be reduced and a symmetrical spray pattern can be achieved. Furthermore, the spray channel comprises a point with an inlet channel to which nebulizing gas can be supplied to the mixed components before exiting the spray channel. Furthermore, at the outlet of the spray channel, at least one gas outlet opening is provided at the outlet of the spray channel, around the outlet at the outlet, by means of which a gas for influencing the spray pattern or, respectively, the spray cone angle is sprayed The spray geometry can be ejected.

It can be selectively sprayed by individual variation of pressure and amount of gas ejected each of the above gas supplies, or by varying the amount, or switching off the mixed plastic components during a spraying a variety of areas and boundaries are better adhered to without adjacent surfaces also be sprayed.

This gas outlet opening can be arranged as a hole or slot partially or completely around the outlet of the spray channel around, whereby the spray radius can be influenced locally. Likewise, a plurality of gas outlet openings can be provided, which likewise influences the spray radius, but at the same time also makes it possible to influence only in individual directions, by ejecting the gas only from individual openings.

Brief description of the drawings

1 shows a spray head according to the invention, in which the adjusting piston is in the rest position;

2 shows a spray head according to the invention, in which the actuating piston is in the operating position;

3a to 3c show various embodiments of the limiting opening in an enlarged view.

Description of preferred embodiments

In the 1 and 2 is a spray head 1 according to the present invention each shown as a schematic diagram.

The spray head 1 consists essentially of a main body 2 with a hole extending through the main body 2 extends. In this hole is an actuator piston 3 arranged in the bore between a rest position ( 1 ) and an operating position ( 2 ) can be moved axially. In the main body 2 is a mixing chamber 4 formed, which is in the operating position of the actuating piston 3 from now not by the actuator piston 3 sealed bore portion at an end portion of the bore in the main body 2 results.

The transition from the mixing chamber 4 in the spray channel 8th is "soft" as a conical narrowing or widening.

The adjusting piston 3 In its rest position, it does not have to be the entire mixing chamber 4 in the main body 2 to take (as in 1 shown). The main body and the other components of the spray head are preferably made of metal

Further, in the main body 2 Flow channels 5a . 5b formed in the mixing chamber 4 lead. Through these flow channels are. Components such as polyol and isocyanate passed into the mixing chamber and mixed there.

The one in the bore of the main body 2 arranged actuating piston 3 blocked in the rest position, the flow channels 5a . 5b for the mixing components (or their mouths) while in the operating position of the piston 3 the mouths of the flow channels 5a . 5b are released and so the inflow of the mixing components in the mixing chamber 4 enable.

In the in 1 embodiment shown has the mixing chamber 4 at the point where the heats 5a . 5b into the mixing chamber 4 open, the same diameter as the bore in which the actuator piston 3 is arranged, whereby the blockage by the adjusting piston 3 is possible.

As previously described, the actuator piston moves axially forward and backward in the bore. In the present embodiment, the operating position of the piston is in a retracted position and the rest position is in an advanced position.

The movement of the piston is preferably generated (electro) pneumatically, but also (electro) magnetic or (electro) hydraulic or mechanical embodiments of the piston movement are conceivable.

In the main body 2 are also return channels 6a and 6b for the components through which the components flow back into a corresponding container (eg a collection tank) when the piston is in a rest position. In 1 this is shown by a preferred embodiment, so that from the heats 5a . 5b the components via grooves 15 , which extend in the axial direction of the piston, in the returns 6a . 6b flow. As a result, the components can always be kept in motion and circulated so that the components do not harden in the channels.

The spray head 1 also has a spraying device 7 with a spray channel 8th through which the mixed components from the mixing chamber 4 from the mixing device 1 be ejected. The sprayer 7 can be integral with the main body 2 be formed, but is preferably an independent element, for example. By gluing, screwing or with a positive connection (press fit, clip connection with hook-shaped projections) on the main body 2 is attached. The sprayer 7 will be described in more detail below.

In the mixing chamber 4 also opens a feeder channel 16 , through which a gas simultaneously with the components in the mixing chamber 4 can be initiated. The feed channel 16 opens at least in the operating position of the actuating piston 3 into the mixing chamber 4 , The gas introduced by turbulence ensures that the mixing of the components and thus the spray pattern is improved.

In a preferred embodiment, the feed channel is 16 aligned so that he is on the spray channel 8th in the spray head 7 is directed. In particular, the feed channel 16 in the area of its mouth (into the mixing chamber 4 ) and the Entry opening in the spray channel 8th (from the mixing chamber 4 out) designed coaxially.

In the preferred embodiment, the feed channel is 16 through the actuator piston 3 formed and is in the operating position of the actuating piston with a first inlet bore 9 in communication, via which a gas jet into the feed channel 16 can be initiated.

Further, a second inlet bore 10 provided in the rest position of the actuating piston 3 with the supply channel 16 communicates and via which a cleaning agent (eg gas) via the supply channel 16 in the spray channel 8th can be introduced.

The sprayer 7 is, as already noted, integral with the main body 2 or designed as a fastenable attachment. The spray channel of the sprayer 7 is with the mixing chamber 4 in the present case directly connected, but can also be connected via other intermediate elements with her. In the preferred embodiment, the spray head is 7 rod-shaped and in particular has a deflection section 11 on, in which the channel undergoes a curvature, so that the component mixture is deflected.

The curvature has a bend angle of inlet 11a and spout 11b from 45 ° to 135 °, more preferably 80 ° to 100 ° or substantially 90 °. By such a deflection a better geometry for the surfaces to be sprayed is generated, since it is easier to get to even hidden and crooked surfaces. In order to compensate for the energy lost by the deflection of the component mixture and above all, an improved discharge of the component mixture can be achieved, can at the deflection 11 a nebulizer channel 12 be provided. Through the atomizer channel 12 Preferably, a gas such as air is introduced into the spray channel, so that the introduced gas, the component mixture toward the outlet 14 the spraying device 7 accelerated (the atomizer channel is preferred to the spout 11b of the deflection section 11 aligned).

For example, the atomizer channel can open into the spray channel so that the two axes of the channels (atomizer and spray channel) form an acute angle α (see FIG. 1 ). However, in the present embodiment, it is preferable that the atomizer channel is coaxial with the exit 11b of the deflection section 11 is arranged.

As in the 3a to 3c can be seen at the exit 14 the spraying device 7 one or more openings 13 be arranged, preferably around the outlet 14 are arranged around. Through these openings 13 a gas can be ejected with which the spray pattern of the spray jet of the spray head can be influenced. It may also be provided only a small punctiform opening on any side of the spray. However, it is preferred that the opening is slit-shaped around the exit (for example, (semicircular)) or a plurality of point or slot-shaped openings which are preferably arranged uniformly around the exit at four, eight or sixteen locations. To these openings leads an air duct 15 (or more channels 15 ), which is connected to a gas supply.

All gas channels of this invention are preferably supplied with (compressed) air, but various other gases may be used.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2008/122400 A1 [0003]
• DE 112005000794 T5 [0003]

Claims (8)

Spray nozzle ( 1 ) for mixing and spraying reactive plastics, comprising: a main body ( 2 ) having a bore extending in the axial direction; a mixing chamber ( 4 ) formed in the axial direction of the bore at its end portion and mixed in the components for the plastic; at least two flow channels ( 5a . 5b ) for the components of the plastic that enter the mixing chamber ( 4 ); an actuator piston ( 3 ) located in the bore of the main body ( 2 ) and between an operating position in which the flow channels ( 5a . 5b ) with the mixing chamber ( 4 ), and a rest position is switchable, in which the connection from the flow channels ( 5a . 5b ) and the mixing chamber ( 4 ) by the actuating piston ( 3 ) is interrupted; and a spraying device ( 7 ), in which a spray channel ( 8th ) is formed, through which the mixed components of the outlet opening ( 14 ) are supplied; characterized in that the adjusting piston ( 3 ) a supply channel ( 16 ), which in the operating position of the actuating piston ( 3 ) into the mixing chamber ( 4 ), so that a gas jet, which via a first inlet bore ( 9 ), from the supply channel ( 16 ) simultaneously with the components of the plastic in the mixing chamber ( 4 ) is introduced, and in the rest position of the actuating piston ( 3 ) a cleaning agent via a second inlet bore ( 10 ) via the supply channel ( 16 ) in the spray channel ( 8th ) can be introduced. Spray nozzle ( 1 ) according to claim 1, wherein the supply channel ( 16 ) on the spray channel ( 8th ), preferably in a coaxial configuration of feed channel ( 9 ) and spray channel ( 8th ). Spray nozzle ( 1 ) according to claim 1 or 2, wherein the main body ( 2 ) two return channels ( 6a . 6b ), which in the rest position of the piston via a groove ( 15 ) with the flow channels ( 5a . 5b ) are connected. Spray nozzle ( 1 ) according to one of the preceding claims, in which at one point ( 11 ) in the spray channel ( 8th ) via an inlet channel ( 12 ) can be supplied to the mixed components atomizing gas. Spray nozzle ( 1 ) according to claim 4, wherein the inlet channel ( 12 ) on the outlet channel ( 14 ), preferably in a coaxial configuration of inlet channel ( 12 ) and exit channel ( 14 ). Spray nozzle ( 1 ) according to one of the preceding claims, wherein at the outlet ( 14 ) of the spray channel ( 8th ) around the exit ( 14 ) around at least one opening ( 13 ) is provided, by means of which a gas for further influencing the spray pattern can be ejected. Spray nozzle ( 1 ) according to one of the preceding claims, in which the transition from the mixing chamber ( 4 ) in the spray channel ( 8th ) tapers to the cross section of the spray channel. Spray device for mixing and spraying reactive plastics, comprising a spray head ( 1 ) according to one of claims 1-7, a metering unit with at least two containers for the components of the plastic, which are connected to the flow channels and preferably also with the return channels; a device for supplying the gas channels with a gas; and a control unit for the actuating piston ( 3 ).

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