JP6022760B2 - Nozzle head and rotary spray having the same - Google Patents

Description

  The present invention relates to a nozzle head for rotating spray for applying a coating material on an object,

  Having a bell-shaped dish with an outflow surface rotatable about an axis of rotation, on which the coating material is discharged in the following direction, i.e. in a direction away from the bell-shaped dish, It can be supplied.

  The invention further relates to a rotating spray with a nozzle head for applying a coating material on an object.

  Rotating sprays equipped with the aforementioned types of nozzle heads are used, for example, in the automotive industry to paint objects such as parts of the vehicle body or to coat them with protective materials.

  In this case, a bell-shaped dish is used for spraying the coating material, so that the bell-shaped dish is driven to rotate about its axis of rotation at a very high rotational speed of 10,000 to 100,000 per minute.

  A rotating bell-shaped dish is fed with the selected coating material. Based on the centrifugal force acting on the coating material, the coating material is moved outward as a film on the bell dish and reaches a terminal edge located radially outward of the bell dish. This high centrifugal force thus acts on the coating material so that it is ejected tangentially in the form of fine coating material droplets.

  In that case, drops of various sizes are produced that spread over a relatively wide size range. In that case, relatively large drops are ejected radially outwards smaller than small drops. The aforementioned type of nozzle head and rotating spray form a relatively wide spray beam, which is ideally conical and has a relatively large cone angle.

  In order to focus this spray beam onto the object to be coated, known rotary sprays act, for example, electrostatically. In this case, the coating material to be applied is charged, while the object to be coated is grounded. In that case, an electric field is formed between the rotating spray and the object, by which the charged coating material is directed and applied onto the object. However, this only works on objects that are electrically conducting.

Instead of or in addition to electrostatic drive, an air guide device is formed in a known rotary spray. Thereby, a generally ring-shaped guide air stream is guided onto the spray beam and bundled to guide drops of various sizes onto the object to be coated.
However, in part, a strong guide air flow is required for this purpose, and forming it is relatively cumbersome.

    The object of the present invention is to ensure that the generated spray beam is focused on the object in the aforementioned kind of nozzle head and rotary spray with as little structural effort as possible.

  This problem is solved by the following in the above-described type of nozzle head.

The bell-shaped dish is formed with a Laval annular nozzle having a discharge annular gap which is rotationally symmetric with respect to the rotation axis, from which the working fluid is blown onto the coating material discharged from the bell-shaped dish. Is possible.
In a Laval nozzle, the passing cross section for the working fluid flowing through first narrows and then widens in the direction of the outflow opening. Thereby, the working fluid flowing through is significantly accelerated, so that no further measures are required.

  As mentioned above, the coating material released from the bell dish is present in the form of drops of various sizes. When the working fluid, usually air, is significantly accelerated out of the discharge annular gap and abuts against a relatively large drop, these drops are broken into multiple smaller drops by air impact, which To homogenize the spray beam with respect to drop size. Since smaller droplets are not emitted farther radially outward than larger droplets, the resulting spray beam is bundled compared to a spray beam generated without a Laval annular nozzle, Thereby focusing on the object to be coated.

  It is particularly effective if the outer surface of the bell-shaped dish is surrounded by a surface of the guide body which is rotationally symmetric with respect to the axis of rotation, and that surface forms a Laval annular nozzle with the outer surface of the bell-shaped dish. It is. In this way, the outer surface of the bell dish can be used as the flow surface of the Laval annular nozzle.

  The Laval annular nozzle can be formed particularly well when the outer surface of the bell-shaped dish forms a truncated cone surface.

  In this case, it is particularly preferred if a conical annular passage is formed between the outer surface of the bell-shaped dish and the surface of the guide body, in which case the surface is oriented in the direction of the outer surface of the bell-shaped dish. It has a facing rotationally symmetric ridge, which defines the constriction of the annular passage.

The outer surface of the bell-shaped plate or the surface of the guide body supports the guide blade, and when the guide blade rotates as follows, that is, when the bell-shaped plate rotates, the outer surface of the bell-shaped plate and the guide body When the working fluid lying between the surfaces is arranged to be delivered to the discharge annular gap of the Laval annular nozzle, it allows the working fluid to be drawn from the reservoir into the Laval annular nozzle. In that case, an additional feeding device for the working fluid can be omitted.
In that case, it is particularly advantageous if the guide body has at least one passage through which fluid can flow from the surroundings into the annular passage. In this case, an external source for the working medium is no longer necessary, but rather the rotating spray or the atmosphere around the nozzle head is used.

  It is preferred if the passage cross section of the Laval annular nozzle is adjustable at least at its constriction. Thereby, the final velocity of the working fluid flowing out of the Laval annular nozzle can be adjusted.

  This can preferably be achieved by the fact that the relative position of the bell-shaped pan and the guide body relative to each other is adjustable with respect to its axis. Preferably, the guide body can be slid axially with respect to the bell-shaped dish and fixed at various axial positions. With respect to the aforementioned type of rotary spray, the above-mentioned problems are likewise solved by the fact that the nozzle head is formed according to any one of claims 1 to 7.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is an axial sectional view showing the spray head of the rotary spray according to the present invention along the cutting line II in FIG. 2, in which a Laval annular nozzle is formed. It is sectional drawing which shows the nozzle head shown in FIG. 1 along the cutting line II-II. FIG. 2 is a cross-sectional view similar to FIG. 1, where the effect of the air flow generated by the Laval nozzle is clarified.

  In FIG. 1, the rotational spray is shown as a whole by the reference numeral 2, of which only the head portion 4 having the nozzle head 6 is shown. The rotating spray 2 allows the paint to be applied on an object not shown as such.

  The nozzle head 6 has a rotationally symmetrical bell-shaped dish 8. In the embodiment described here, the bell-shaped dish is formed as a hollow truncated cone 10 having a wall 12 that circulates as a whole, and has a frustoconical inner surface 14 and a frustoconical outer surface. 16. The bell-shaped dish 8 can also have a different geometry, as is known per se in bell-shaped dishes according to the prior art.

The bell-shaped dish 8 can rotate at high speed about its rotational axis 18, for which reason the rotary spray 2 has a drive device 20, which is shown schematically only in FIGS. 1 and 3. Yes. The bell-shaped dish 8 can be driven, for example, by an electric motor or pneumatically. The bell-shaped pan 8 rotates around its rotating shaft 18 at a rotational speed of 10,000 to 100,000 min ^-1 during driving.

  The bell-shaped dish 8 is supported by a free end portion of a hollow shaft 22 coaxial with the bell-shaped dish 8, and the hollow shaft is coupled to the driving device 20 and has a paint supply passage in the longitudinal direction. 24 can be defined and supplied to the paint supply passage from a paint reservoir (not shown).

  The hollow shaft 22 ends in a fixed flange 26 extending perpendicularly to the rotary shaft 18, and the hollow shaft is coupled to the bell-shaped dish 8 through the fixed flange. For this purpose, the bell-shaped dish 8 has a ring plate 28 with a central discharge opening 30 which is complementary to the fixing flange 26 of the hollow shaft 22, and the paint supply passage 24 in the hollow shaft 22. Communicates into the discharge opening.

  As is known per se, the bell-shaped dish 8 has a recoil plate 32, which is supported by a ring plate 28. The recoil plate 32 extends perpendicularly to the rotational axis 18 of the bell-shaped dish 8 and is disposed inside the bell-shaped dish 8 at a slight distance from the ring plate 28. The recoil plate 32 extends radially outward to the front of the inner surface 14 of the bell-shaped dish 8, and the inner surface is used as a frustoconical outflow surface 34. Accordingly, the outer diameter of the outflow surface 34 increases in a direction away from the hollow shaft 22. The outflow surface 34 ends at the end edge 36 that makes a round at the end away from the hollow shaft 22.

  The outer surface 16 of the bell-shaped dish 8 is surrounded by an inner surface 38 which is rotationally symmetric with respect to the outer surface 16 of the guide body which is formed as a conical guide sleeve 40, the guide body being bell-shaped. It is arranged coaxially with respect to the dish 8. The guide sleeve 40 has a free end edge 42, which is arranged in the radial direction of the outer surface of the bell-shaped dish 8, so that a discharge annular gap 44 is formed there. Yes.

  The inner surface 38 of the guide sleeve 40 has a portion 44 which is bent in a direction approaching the outer surface 16 of the bell-shaped dish 8 when viewed inward from the free end edge 42 and forms a ridge. , That portion has transitioned to a conical portion 48 that extends parallel to the outer surface 16 of the bell-shaped dish 8 while maintaining a spacing. Thereafter, the conical portion 48 communicates into a hollow cylindrical support 50 having a constant cross section, which surrounds the hollow shaft 22 and secures the guide sleeve 40 to the rotary spray 2. Used for.

  The guide sleeve 40 is fixedly supported with respect to rotation with respect to the rotatable bell-shaped dish 8, but can slide in the axial direction and has various axial positions relative to the bell-shaped dish 8. Can be fixed to.

  Overall, an annular passage 52 is formed between the outer surface 16 of the bell-shaped dish 8 and the inner surface 38 of the guide sleeve 40, the narrowest portion 54 of which is defined by the ridge 46.

In this way, the inner surface 38 of the guide sleeve 40 coaxial to the bell-shaped dish 8 forms a Laval annular nozzle 56 with the outer surface 16 of the bell-shaped dish 8, which has a discharge annular gap 44. From there, the working fluid is blown onto the coating material discharged from the bell-shaped dish 8. In that case, the inner surface 38 of the guide sleeve 40 forms the first flow surface of the Laval annular nozzle 56 and the outer surface 16 of the bell-shaped pan 8 forms the second flow surface, which are opposed to each other. doing.
Accordingly, in general terms, a bell-shaped pan 8 is formed with a Laval annular nozzle 56 which is rotationally symmetric with respect to the rotational axis 18 and has a discharge annular gap 44 from which a working fluid can flow. Can be blown onto the coating material discharged from the bell-shaped dish 8.

  In this embodiment, air is used as the working fluid. For this purpose, a plurality of through passages 58 are formed in the circumferential direction of the conical portion 48 of the guide sleeve 40 adjacent to the cylindrical portion 50, through which the annular passage 52 passes the nozzle head 6. Can communicate with surrounding air. Furthermore, the bell-shaped dish 8 has guide blades 60 distributed uniformly in the circumferential direction on the outer surface 16 thereof. The guide blade has a geometrical arrangement such that when the rotary spray 2 is driven and the bell-shaped pan 8 rotates, air is sucked from the annular passage 52 and fed toward the discharge gap 44. And it is arranged like that. In that case, a negative pressure is created in the annular passage 52, whereby the air surrounding the nozzle head 6 is sucked into the annular passage 52 via the passage passage 58 and is therefore used as working fluid.

  The rotary spray 2 described above functions as follows.

  When the rotary spray 2 is driven, the bell-shaped dish 8 is rotated around the rotation shaft 18 by the driving device 20, and the paint is supplied to the paint supply passage 24 in the hollow shaft 22.

  In this case, the paint first flows out from the discharge opening 30 in the annular gap 28 of the rotating bell-shaped dish 8 and comes into contact with the recoil plate 32. This paint reaches the outflow surface 34 located on the inside as a paint film by the rotation of the bell-shaped dish 8, and further reaches the end edge 36 forward, where the paint film is in the form of paint drops. Released at. In that case, drops of various sizes are generated that spread over a relatively large area. This drop formation is illustrated in FIG. 3, where a relatively large drop 62 and a relatively small drop 64 are shown.

  Air is uniformly blown from the discharge annular gap 44 onto the drops 62 and 64 discharged from the end edge 36 by a guide blade 60 provided on the outer surface 16 of the rotating bell-shaped dish 8. This air has a high outflow velocity that results in a pressure shock on the paint drops 62 and 64 in the discharge gap 44 based on the formation of the Laval annular nozzle, This is suggested in FIG. This pressure shock 66 splits the larger drop 62 into a plurality of smaller drops 64. This is suggested in FIG. 3 by a small arrow 68.

  In the relatively small droplet 64 itself, the pressure impact has no significant effect. Therefore, as a whole, the medium-sized paint droplets discharged from the end edge 36 of the bell-shaped dish 8 are unified.

  Thus, there is at least a slightly larger and therefore heavier drop 64 that is transported further radially outward than the smaller and thus lighter paint drop 62 by centrifugal force.

  In this way, the diameter of the paint mist formed by the nozzle head 6 is smaller than that without the Laval annular nozzle 56 and the paint mist is focused on the object to be painted.

  As described above, the guide sleeve 40 is slid axially with respect to the bell-shaped dish 8 and can be fixed at an axial position slid with respect to the bell-shaped dish 8 and its outer surface 16. Thereby, the passage cross-sectional area of the narrowed portion 54 of the annular passage 52 of the Laval annular nozzle 56 can be adjusted.

  When the guide sleeve 40 is moved rearward with respect to the bell-shaped pan 8, the passage cross section at the narrowed portion 54 of the annular passage 52 of the Laval annular nozzle 56 increases. Along with this, the passage cross section of the annular passage 52 in the region of the conical part 48 of the guide sleeve 40 also increases. In that case, the velocity of the air flowing out of the discharge gap 44 of the Laval annular nozzle 56 and the resulting pressure impact on the droplet 64 is reduced.

  On the other hand, when the guide sleeve 40 is slid forward relative to the bell-shaped dish 8, the passage cross section at the narrowed portion 54 of the annular passage 52 of the Laval annular nozzle 56 is reduced. Accordingly, the passage cross section of the annular passage 52 in the region of the conical portion 48 of the guide sleeve 40 is also reduced. In that case, the velocity of the air flowing out of the discharge gap 44 of the Laval annular nozzle 56 and the resulting pressure impact on the drop 54 is increased.

  Thus, at least a part of the outer surface 16 of the bell-shaped dish 8 is always surrounded by at least one part of the inner surface 38 of the guide sleeve 40. In a variant, the guide blade 60 can also be provided on the inner surface 38 of the guide sleeve 40 instead of being provided on the outer surface 16 of the bell-shaped dish 8. In this case, the guide blade 60 is fixed, but the desired action is obtained because the rotational speed of the bell-shaped dish 8 is high.

  In another variation, compressed air can be supplied from a compressed air source to the annular passage 52 of the Laval annular nozzle 56 via a compressed air conduit, in which case the compressed air is used as a working fluid. In this case, the guide blade 60 can be omitted in some cases.

  In other variants, the Laval annular nozzle 56 can also be provided as a separate component that encloses the bell-shaped dish 8 accordingly. In this case, the outer surface 16 of the bell pan 8 does not form the second flow surface of the Laval annular nozzle; rather, in this case, this flow surface is provided by a separate component.

Claims (6)

A bell dish (8) having an outflow surface (34) rotatable about a rotation axis (18), the coating material being applied to the outflow surface from the bell dish (8). In a nozzle head for a rotating spray for applying a coating material onto an object, which can be supplied to be released,
The bell-shaped plate (8) is formed with a Laval annular nozzle (56) having a discharge annular gap (44) that is rotationally symmetric with respect to the rotation axis (18), and a working fluid is passed through the discharge annular gap. , Ri can der sprayed onto the coating material emitted from said bell-shaped dish (8),
The outer surface (16) of the bell-shaped dish (8) is surrounded by a surface (38) of the guide body (40) which is rotationally symmetric with respect to the rotational axis (18), the surface being a bell-shaped dish. Together with the outer surface (16) of (8), a Laval annular nozzle (56) is formed,
An annular passage (52) is formed between the outer surface (16) of the bell-shaped dish (8) and the surface (38) of the guide body (40), in which case the surface (38) is a bell. A rotationally symmetrical ridge (46) facing the direction of the outer surface (16) of the plate (8), said ridge defining a constriction point (54) of the annular passage (52);
A nozzle head for rotary spraying, characterized in that the passage cross section of the Laval annular nozzle (56) is adjustable at least at its constriction (54) . Nozzle head according to claim 1, the outer surface (16) forms a truncated cone surface, it is characterized by the bell-shaped dish (8). The outer surface (16) of the bell-shaped dish (8) or the surface (38) of the guide body (40) supports the guide blade (60), and the guide blade rotates the bell-shaped dish (8). In this case, the working fluid between the outer surface (16) of the bell-shaped pan (8) and the surface (38) of the guide body (40) is discharged into the discharge annular gap (44) of the Laval annular nozzle (56). The nozzle head according to claim 1 , wherein the nozzle head is arranged so as to be fed to the nozzle head. The guide body (40) has at least one through passage (58) through which fluid from the surroundings can flow into the annular passage (52). Item 4. The nozzle head according to any one of Items 1 to 3 . The passage cross section of the Laval annular nozzle (56) is adjustable at least at its constriction (54);
A nozzle according to any one of the preceding claims, characterized in that the relative position of the bell-shaped dish (8) and the guide body (40) relative to each other is adjustable with respect to its axis (18). head. In a rotating spray with a nozzle head (6) for applying a coating material onto an object,
A rotary spray, characterized in that the nozzle head (6) is formed in the nozzle head (6) according to any one of claims 1 to 5 .

Images