GB2469539A

GB2469539A - A rotary device for transmitting material

Info

Publication number: GB2469539A
Application number: GB0916423A
Authority: GB
Inventors: Dau Binh Chiu
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-09-21
Filing date: 2009-09-21
Publication date: 2010-10-20
Anticipated expiration: 2029-09-21
Also published as: GB0916423D0; WO2011032906A1; GB2469539B

Abstract

A rotary device for transmitting material comprises a body having a portion with a substantially conical surface 7, and a cup / bell-shaped member 3 rotatably mounted in the body 5 and having a substantially conical surface 9 adjacent to and spaced from the conical surface of the body to define a first flow path of air. The conical surface of the body comprises at least one first opening 11 for directing air at the conical surface of the bell-shaped member along a second flow path which intersects the first flow path. At least one second opening 13 is provided spaced radially outside the first opening to form a third flow path. The rotary transmission / projection device is preferably used to spray atomised paint powder / particulate towards a surface to be coated. The second flow path is preferably at an angle to the device's longitudinal axis. Apparatus for generating high-voltage electrostatic charge may be employed to improve transmission.

Description

ROTARY DEVICE AND METHOD FOR TRANSMITTING MATERIAL

This invention relates to a rotary device and to a method for transmitting material. The device and the method may be used for transmitting material, such as paint, for example in particulate form, for deposition on a target surface.

Rotary devices are known, for example from EP-A-0780159, in the form of electrostatically controlled devices for transmitting a beam of material in particulate form at a target surface to be coated, the device comprising a bell-shaped member which is rotatable about a principal axis and arranged to project a conical curtain of small particles flowing generally towards a target surface.

A high-voltage electrostatic charge is applied between the target surface and the particles to assist in directing the particles towards the target surface.

Generally the material to be deposited, such as paint, will be a liquid or suspension, but other suspended materials, solids and powders can be handled in this way dependent on the application provided they are able to be in particulate form when airborne.

Such rotary devices are often mounted on the end of a robot arm and the robot arm is provided within a spray booth. The electrostatic charge not only directs the particles towards the target surface, but additionally minimisesthe deposition of particles on surfaces other than the target surface, such as parts of the rotary device not directly in contact with the particles, the robot arm and the interior of the spray booth. R would be advantageous to be able to minimise the deposition of particles on surfaces otherthan the target surface without using a high-voltage electrostatic charge, which is costly to produce and potentially dangerous.

It is therefore an object of the present invention to provide a rotary device and a method fortransmitting material which overcomes, or at least ameliorates, the above disadvantages.

According to one aspect of the present invention there is provided a rotary device for transmitting material, the device comprising: a body having a substantially conical surface; a bell-shaped member mounted in the body and rotatable about an axis relative to the body, the bell-shaped member being formed with a substantially conical surface adjacent to and spaced from the substantially conical surface of the body so as to form a first flow path for air in the device; means for providing a flow of air along the first flow path; at least one first opening provided in the conical surface of the body for directing air at the substantially conical surface of the bell-shaped member along a second flow path which intersects with the first flow path; and at least one second opening provided spaced radially outside the at least one first opening for directing air along a third flow path.

The at least one first opening may be a single opening, for example in the form of a slot which extends around the entire periphery of the bell-shaped member.

The width of the slot may be varied, for example by providing opposite sides of the slot in different concentric members which are movable axially relative to each other, for example by way of a thread.

Alternatively, the at least one first opening may comprise a plurality of openings, for example circular, slot or square form, spaced around the periphery of the bell-shaped member.

The at least one second opening may be provided in a substantially conical surface which contracts towards the end of the device. Alternatively, the at least one second opening may be provided in a radial surface. As a further alternative, the at least one second opening may be provided separately from the body, for example as a toroidal member positioned around the bell-shaped member.

The at least one second opening may be a single opening, for example in the form of a slot which extends around the periphery of the at least one first opening. The width of the slot may be varied, for example by providing opposite sides of the slot in different concentric members which are movable axially relative to each other, for example by way of a thread.

Alternatively, the at least one second opening may comprise a plurality of openings, for example circular, slot or square form, spaced around the at least one first opening.

The at least one second opening may be directed at an angle in the range from to 80 degrees, preferably 20 to 70 degrees and ideally about 30 degrees, relative to the axial direction of the bell-shaped member.

At least one third opening for the passage of air may be provided in a region radially within the rotatable bell-shaped member. The third opening may be provided between the bell-shaped member and a stationary central support member, or may be provided in the stationary central support member.

A nozzle for the material to be transmitted may be provided in the central support member. Where the at least one third opening is provided in the central support member, the opening may be a single annular opening or may comprise a plurality of openings, for example circular, slot or square form, spaced around the nozzle.

According to another aspect of the present invention there is provided a method for transmitting material employing a rotary device as hereinbefore defined, the method comprising the steps of: providing the material to be transmitted so as to be atom ised through rotation of the bell-shaped member; entraining the atomised material in a first substantially conical curtain of air formed by air flowing along the first flow path and by air from the at least one first opening and flowing along the second flow path intersecting with the first flow path; and providing a second substantially conical curtain of air along the third flow path around the periphery of the first curtain for limiting the spread of the atomised material.

The inner and outer curtains of air may merge to create a substantially conical vortex which rotates about the axis of the bell-shaped member so as to create a region in the vicinity of the bell-shaped member which has a lower pressure than the pressure externally of the air flowing along the first, second and third flow paths.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying figure which is a side view, partly in cross-section, of one embodiment of a rotary device for transmitting material according to the present invention.

The rotary device for transmitting material shown in the figure is generally of conventional construction, for example as described in EP-A-0 780 159, except that no apparatus is necessary for generating a high-voltage electrostatic charge, although this may be provided as an option, and means is provided for providing inner and outer air curtains for shaping and directing a conical curtain of coating material towards a surface 1 to be coated, the surface 1 being shown diagrammatically.

As shown in the figure, a rotatable bell-shaped member 3 is provided, the bell-shaped member being rotatable about its principle axis at speeds from 5000 to 100000 rpm, using, for example, air bearings or ball bearings, in order to create an atomised coating material. In the illustrated embodiment, the bell-shaped member 3 is rotatable by means of an air-driven turbine 19. The bell-shaped member 3 is rotatably mounted on a stationary central support member 23 through which passes an outlet nozzle 17 for material which is to be directed towards the surface I to be coated, and is mounted within a stationary body 5 which is formed with a substantially conical surface 7 adjacent to, but spaced from an external substantially conical surface 9 of the bell-shaped member 3.

The conical surfaces 7 and 9 both expand towards the outer end of the device.

Exhaust air from the turbine 19 and/or from air beanngs, where provided, passes along channels within the body 5, such as channel 21, and exits the device through a flow path provided by the annular space between the outer surface of the bell-shaped member 3 and the body 5. If neither a turbine nor air bearings are employed, or if the air they consume is not employed, a separate source of air is provided to create a flow of air through the annular space between the bell-shaped member 3 and the body 5.

A further channel 25 for the passage of air is provided between the central support member 23 and the rotatable bell-shaped member 3. In an alternative embodiment (not shown) in which the rotatable bell-shaped member 3 is integral with the rotatable central support member 23, a channel 27 for the passage of air is provided between the central support member 23 and the nozzle 17 for the material to be directed towards the surface 1 to be coated. The channel 25 or 27 provides an additional supply of air which may be used particularly in the event the material contains large particles.

One or more openings 11 is or are provided in the conical surface 7 so as to direct shaping air along a flow path towards the bell-shaped member 3, especially the conical surface 9 thereof. The one or more openings 11 may be a single opening in the form of a slot which extends around the entire periphery of the bell-shaped member. Alternatively, the one or more openings may comprise a plurality of openings, for example of circular, slot or square form, spaced around the periphery of the bell-shaped member 3.

Where a single slot 11 is provided, the width of the slot may be varied, for example by providing opposite sides of the slot in different concentric members which are movable axially relative to each other, for example by way of a thread.

As explained above, the opening or openings 11 is or are directed towards the bell-shaped member 3, especially the conical surface 9 thereof. Where the bell-shaped member has an included angle in the region of 60 degrees as illustrated, the opening or openings may be at a specific angle relative to the axis of the bell-shaped member 3. The angle may be in a range of 10 to 75 degrees relative to the axial direction, preferably in a range 20 to 70 degrees and ideally at an angle of substantially 60 degrees to the axial direction. However, other angles may be employed.

In use of the device, with the bell-shaped member rotating at high speed, the flow of air between the bell-shaped member 3 and the body 5 interacts with the flow of air directed towards the bell-shaped member from the opening or openings 11. The result is a turbulent inner curtain of air which passes the leading edge of the bell-shaped member and flows towards the surface 1 to be coated.

Additionally, one or more openings 13 is or are provided spaced radially outside the opening or openings 11. The opening or openings 13 may be provided in a substantially conical surface 15 which contracts towards the end of the device.

That is, the conical surfaces 7 and 15 are in opposite senses and converge towards each other towards the end of the device. It is not essential that surface is conical: as an alternative, surface 15 may be radial. As a further alternative, the opening or openings 13 may be separate from the body 5, for example provided in a toroidal member which is positioned around the bell-shaped member 3.

The one or more openings 13 is or are provided in the conical surface 15 so as to form a conical outer air curtain along a flow path which contributes towards controlling the flow of atom ised particles towards the surface 1 to be coated.

Consequently, the inner air curtain and the outer air curtain co-operate to form concentric cones of air which control the flow of the atom ised particles towards the surface 1 and constrain the spread of the atomised particles.

While the inner and outer curtains are initially separate, with increasing distance from the device they merge and create a generally conical vortex which rotates about the axis of the bell-shaped member 3.

The one or more openings 13 may be a single opening in the form of a slot which extends around the entire periphery of the opening(s) 11. Alternatively, the one or more openings 13 may comprise a plurality of openings, for example of circular, slot or square form, spaced around the periphery of the opening(s) 11.

Where a single slot 13 is provided, the width of the slot may be varied, for example by providing opposite sides of the slot in different concentric members which are movable axially relative to each other, for example by way of a thread.

The opening or openings 13 is or are ideally directed at a specific angle relative to the axis of the bell-shaped member 3. The angle is in a range of 15 to 80 degrees relative to the axial direction, preferably in a range 20 to 70 degrees and ideally at an angle of substantially 30 degrees to the axial direction.

Air may be supplied to the opening or openings 11, 13 in the form of clean, dry air at a pressure of up to about 8 bar, while the material which is to be directed towards the surface 1 to be coated may be at a pressure of about 1 bar.

In practice, the rotation of the vortex resulting from the inner and outer air curtains creates a region within the air curtains, that is in the region of the bell-shaped member 3, which has in use a lower pressure than the pressure externally of the air curtains. The pressure differential helps to propel the atomised particles particularly efficiently towards the surface to be coated without the need for a high-voltage electrostatic charge. The relative flow rates of air can be controlled in any suitable manner, such as by controlling the pressure of the various air sources as well as by controlling the cross-sectional areas of the various openings.

The use of the inner and outer air curtains has a further benefit in that it is possible to keep the device, externally of the bell-shaped member 3, clean as well as any additional spray equipment and spray booth without the need for a high-voltage electrostatic charge.

Claims

CLAIMS1. A rotary device for transmitting material, the device comprising: a body having a substantially conical surface; a bell-shaped member mounted in the body and rotatable about an axis relative to the body, the bell-shaped member being formed with a substantially conical surface adjacent to and spaced from the substantially conical surface of the body so as to form a first flow path for air in the device; (Y) means for providing a flow of air along the first flow path; a) CS.J at least one first opening provided in the conical surface of the body for directing air at the substantially conical surface of the bell-shaped member along a second flow path which intersects with the first flow path; and at least one second opening provided spaced radially outside the at least one first opening for directing air along a third flow path.
2. A rotary device as claimed in claim 1, wherein the at least one first opening comprises a single opening.
3. A rotary device as claimed in claim 2, wherein the single opening is in the form of a slot which extends around the entire periphery of the bell-shaped member.
4. A rotary device as claimed in claim 3, wherein the width of the slot can be varied.
5. A rotary device as claimed in claim 4, wherein the width of the slot can be varied by providing opposite sides of the slot in different concentric members which are movable axially relative to each other.

(Y)
6. A rotary device as claimed in claim 5, wherein the different concentric members are movable axially relative to each other by way of a thread. a) (\J
7. A rotary device as claimed in claim 1, wherein the at least one first opening comprises a plurality of openings spaced around the periphery of the bell-shaped member.
8. A rotary device as claimed in claim 7, wherein the first openings are selected from circular, slot and square form.
9. A rotary device as claimed in any preceding claim, wherein the at least one second opening is provided in a substantially conical surface which contracts towards the end of the device. -14-
10. A rotary device as claimed in any one of claims 1 to 8, wherein the at least one second opening is provided in a radial surface.
11. A rotary device as claimed in any one of claims 1 to 8, wherein the at least one second opening is provided separately from the body.
12. A rotary device as claimed in claim 11, wherein the at least one second opening is provided as a toroidal member positioned around the bell-shaped member.
13. A rotary device as claimed in any preceding claim, wherein the at least (Y) one second opening comprises a single opening. a)

(\J
14. A rotary device as claimed in claim 13, wherein the single second opening comprises a slot which extends around the periphery of the at least one first opening.
15. A rotary device as claimed in claim 14, wherein the width of the slot can be varied.
16. A rotary device as claimed in claim 15, wherein the width of the slot can be varied by providing opposite sides of the slot in different concentric members which are movable axially relative to each other.
17. A rotary device as claimed in claim 16, wherein the different concentric members are movable axially relative to each other by way of a thread.
18. A rotary device as claimed in any one of claims 1 to 12, wherein the at least one second opening may comprise a plurality of openings spaced around the at least one first opening.
19. A rotary device as claimed in claim 18, wherein the second openings are selected from circular, slot and square form.
20. A rotary devices as claimed in any preceding claim, wherein the at least (Y) one second opening is directed at an angle in the range from 15 to 80 degrees relative to the axial direction of the bell-shaped member. a) (\J
21. A rotary devices as claimed in claim 20, wherein the at least one second opening is directed at an angle in the range from 20 to 70 degrees relative to the axial direction of the bell-shaped member.
22. A rotary devices as claimed in claim 21, wherein the at least one second opening is directed at an angle of about 30 degrees relative to the axial direction of the bell-shaped member.
23. A rotary device as claimed in any preceding claim, wherein at least one third opening for the passage of air is provided in a region radially within the rotatable bell-shaped member.
24. A rotary device as claimed in claim 23, wherein the third opening is provided between the bell-shaped member and a stationary central support member.
25. A rotary device as claimed in claim 23, wherein the third opening is provided in the stationary central support member.

(Y)
26. A rotary device as claimed in claim 24 or 25, wherein a nozzle for the material to be transmitted is provided in the central support member. a) (\J
27. A rotary device as claimed in claim 25 or any claim dependent thereon, wherein the opening comprises a single annular opening.
28. A rotary device as claimed in claim 26, wherein the at least one third opening comprises a plurality of openings spaced around the nozzle.
29. A rotary device as claimed in claim 28, wherein the plurality of third openings are selected from circular, slot and square form.
30. A rotary device for transmitting material substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.
31. A method for transmitting material employing a rotary device as claimed in any preceding claim, the method comprising the steps of: providing the material to be transmitted so as to be atomised through rotation of the bell-shaped member; entraining the atomised material in a first substantially conical curtain of air formed by air flowing along the first flow path and by air from the at least one (Y) first opening and flowing along the second flow path intersecting with the first flow path; and a) (\J providing a second substantially conical curtain of air along the third flow path around the periphery of the first curtain for limiting the spread of the atomised material.
32. A method according to claim 31, wherein the inner and outer curtains of air merge to create a substantially conical vortex which rotates about the axis of the bell-shaped member so as to create a region in the vicinity of the bell-shaped member which has a lower pressure than the pressure externally of the air flowing along the first, second and third flow paths.
33. A method fortransmitting material substantially as hereinbefore described with reference to the accompanying drawings. C) a) (\JAmended claims have been filed as follows:-CLAIMS 19 1. A rotary device for transmitting material, the device comprising: a body having a substantially conical surface; a bell-shaped member mounted in the body and rotatable about an axis relative to the body, the bell-shaped member being formed with a substantially conical surface adjacent to and spaced from the substantially conical surface of the body so as to form a first flow path for air in the device; (Y) means for providing a flow of air along the first flow path; a) CS.J at least one first opening provided in the conical surface of the body for directing air at the substantially conical surface of the bell-shaped member along a second flow path which intersects with the first flow path; and at least one second opening provided spaced radially outside the at least one first opening for directing air along a third flow path.2. A rotary device as claimed in claim 1, wherein the at least one first opening comprises a single opening.3. A rotary device as claimed in claim 2, wherein the single opening is in the form of a slot which extends around the entire periphery of the bell-shaped member.4. A rotary device as claimed in claim 3, wherein the width of the slot can be varied.5. A rotary device as claimed in claim 4, wherein the width of the slot can be varied by providing opposite sides of the slot in different concentric members which are movable axially relative to each other.6. A rotary device as claimed in claim 5, wherein the different concentric members are movable axially relative to each other by way of a thread.7. A rotary device as claimed in claim 1, wherein the at least one first opening comprises a plurality of openings spaced around the periphery of the bell-shaped member.8. A rotary device as claimed in claim 7, wherein the first openings are *.....* 20 selected from circular, slot and square form. *. * * * ** * ***9. A rotary device as claimed in any preceding claim, wherein the at least * one second opening is provided in a substantially conical surface which * * contracts towards the free end of the device.10. A rotary device as claimed in any one of claims I to 8, wherein the at least one second opening is provided in a radial surface.11. A rotary device as claimed in any one of claims I to 8, wherein the at least one second opening is provided separately from the body.12. A rotary device as claimed in claim 11, wherein the at least one second opening is provided as a toroidal member positioned around the bell-shaped member.13. A rotary device as claimed in any preceding claim, wherein the at least one second opening comprises a single opening.14. A rotary device as claimed in claim 13, wherein the single second opening comprises a slot which extends around the periphery of the at least one first opening.15. A rotary device as claimed in claim 14, wherein the width of the slot forming the second opening can be varied.* ***** * * **** 16. A rotary device as claimed in claim 15, wherein the width of the slot S..forming the second opening can be varied by providing opposite sides of the slot * in different concentric members which are movable axially relative to each other I..... S *and which form the slot of the second opening.17. A rotary device as claimed in claim 16, wherein the different concentric members forming the slot of the second opening are movable axially relative to each other by way of a thread, 18. A rotary device as claimed in any one of claims 1 to 12, wherein the at least one second opening may comprise a plurality of openings spaced around the at least one first opening.19. A rotary device as claimed in claim 18, wherein the second openings are selected from circular, slot and square form.20. A rotary devices as claimed in any preceding claim, wherein the at least one second opening is directed at an angle in the range from 15 to 80 degrees relative to the axial direction of the bell-shaped member.21. A rotary devices as claimed in claim 20, wherein the at least one second opening is directed at an angle in the range from 20 to 70 degrees relative to the axial direction of the bell-shaped member. * *S***..S * 20 22. A rotary devices as daimed in claim 21, wherein the at least one second *S..opening is directed atan angle of about 30 degrees relative to the axial direction of the bell-shaped member, S.....23. A rotary device as claimed in any preceding claim, wherein at least one third opening for the passage of air is provided in a region radially within the rotatable bell-shaped member.24. A rotary device as claimed in claim 23, wherein the third opening is provided between the bell-shaped member and a stationary central support member.25. A rotary device as claimed in claim 23, wherein the third opening is provided in the stationary central support member.(Y) 26. A rotary device as claimed in claim 24 or 25, wherein a nozzle for the material to be transmitted is provided in the central support member. a) (\J27. A rotary device as claimed in claim 25 or any claim dependent thereon, wherein the opening comprises a single annular opening.28. A rotary device as claimed in claim 26, wherein the at least one third opening comprises a plurality of openings spaced around the nozzle.29. A rotary device as claimed in claim 28, wherein the plurality of third openings are selected from circular, slot and square form.30. A rotary device for transmitting material substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.31. A method for transmitting material employing a rotary device as claimed in any one of claims 1 to 29, the method comprising the steps of: providing the material to be transmitted so as to be atomised through rotation of the bell-shaped member; entraining the atomised material in a first substantially conical curtain of air formed by air flowing along the first flow path and by air from the at least one first opening and flowing along the second flow path intersecting with the first flow path; and providing a second substantially conical curtain of air along the third flow path around the periphery of the first curtain for limiting the spread of the atomised material.32. A method according to claim 31, wherein the inner and outer curtains of * 20 air merge to create a substantially conical vortex which rotates about the axis of *I�* the bell-shaped member so as to create a region in the vicinity of the bell-shaped S..member which has a lower pressure than the pressure externally of the air * flowing along the first, second and third flow paths.555**S * S 33. A method fortransmitting material substantially as hereinbefore described with reference to the accompanying drawings. C) a) (\J