WO1997035669A1

WO1997035669A1 - Spray booths

Info

Publication number: WO1997035669A1
Application number: PCT/GB1997/000805
Authority: WO
Original assignee: Paint & Powder Systems Limited; Williams, Alan
Priority date: 1996-03-26
Filing date: 1997-03-24
Publication date: 1997-10-02
Also published as: AU2038297A; GB9606431D0

Abstract

A powder coating spray booth (10) comprising a chamber (12) with a constant cross section along its length, with gently curving side walls (18) and more steeply curving upper and lower walls (20), the chamber (12) being arranged such that in use the airflow therein tends to spiral from the entrance (14) to a duct (32) leading to a reduced pressure creating means.

Description

SPRAY BOOTHS

This invention concerns improvements in or relating to spray booths, and particularly but not exclusively spray booths for use in powder coating.

Spray booths are used for powder coating as well as for spray painting and other purposes. In powder coating articles to be coated are generally passed through the booth sequentially in a continuous arrangement, and electrostatically sprayed. The booth is therefore required to be open at one or both ends, and usually at the top to permit a conveyor to extend therethrough. With an open booth it is necessary to provide negative pressure in the booth to prevent sprayed material passing out of the opening or openings in the booth. This is generally provided using a fan arrangement, usually with a separation assembly to remove airborne sprayed material, often for subsequent reuse.

According to the present invention there is provided a spray booth, the booth comprising walls defining a spraying chamber, the chamber being engageable with means for creating reduced pressure in the chamber, and one or more locations in the chamber where spraying can take place, the booth being arranged such that in use air flows in the chamber from the or at least one of the said locations to the reduced pressure creating means in a spiralling motion.

The reduced pressure creatmg means is preferably engageable with the chamber adjacent one end of the chamber, and the or each spraying locations are preferably located towards the other end of the chamber. The booth preferably comprises means for transporting items to be sprayed through the chamber, which means may comprise a conveyor which may extend above the chamber with mounting means extending into the chamber. Desirably the chamber has an entrance at one end and an exit at the other end, with the reduced pressure creating means being preferably locatable adjacent the exit.

The inner walls of the chamber are preferably curved, and desirably substantially all of the inner walls of the chamber are inwardly curved. The chamber is preferably taller than it is wide. The chamber preferably has a substantially constant curved cross-section along its length. The entrance and/or exit are preferably of smaller cross- section than the remainder of the chamber.

The reduced pressure creating means is preferably operable through an outlet from the chamber, and ducting may be provided extending from the outlet to communicate a lower part of the chamber. The ducting may open towards the entrance and/or exit, and/or the ducting may open circumferentially substantially over the floor of the chamber.

The chamber is preferably formed of metal, and may be formed in a number of sections.

The spray booth preferably comprises reduced pressure creating means, and said means preferably comprises a fan for sucking air from the chamber. The reduced pressure creating means may comprise means for recovering sprayed material.

The invention further provides a powder coating spray booth according to any of the preceding seven paragraphs.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:-

Fig. 1 is a diagrammatic side view of a spray booth according to the mvention;

Fig. 2 is a diagrammatic plan view of the booth of Fig. 1;

Fig. 3 is a cross-sectional view along the line X-X of Fig. 1; and

Fig. 4 is an end view of the booth shown in Fig. 1. The drawings show a spray booth 10 comprising a chamber 12 with an entrance 14 at one end and an exit 16 at the other end. The chamber 12 has a constant cross-section along its length with gently curving side walls 18 and more steeply curving upper and lower walls 20. The walls 18 and 20 are formed from a number of sections 22.

A number of locations are provided in the chamber 12 to permit spraying equipment such as electrostatic powder coating guns to extend into the chamber. Two such guns 24 are shown in Fig. 2. An outlet port 26 is provided towards the upper part of a one of the side walls 18 towards the outlet 16. An appropriate seal such as an inflatable seal 28 is provided around the port 26 to permit sealing connection with means for producing reduced pressure such as a sprayed material recovery unit (not shown). Such a unit could be in the form of a multicyclone.

Ducting 30 extends down the side wall 18 from the port 26 onto the lower wall 20 to a further domed duct 32. The duct 32 is open towards the entrance 14 and on each side through a relatively small lower gap 34. An upwardly extending opening 36 is provided through the upper walls 20. A conveyor in the form of a movable chain 38 is provided above the opening 36 with a pluraUty of article support members 40 extending therethrough to support an article 42 to be sprayed. A support member 40 and article 42 are shown in Fig. 3 by way of example.

In use, reduced pressure is created in the chamber 12 through the port 26 by sprayed material recovery means. Articles 42 are passed through the chamber 12 from the entrance 14 to the exit 16 and are sprayed with coating material by the guns 24. The air flow in the chamber 12 tends to spiral from the entrance 14 to the domed duct 32, generally around the articles 42.

This spiralling air flow is advantageous in providing a secondary coating on the articles 42 and thereby reducing wastage of sprayed material. This air flow is set up by providing curved walls 18,20 right around the chamber 12 and also locating the port 20 and connecting ducting 30,32 towards the exit 16.

There is thus described a spray booth 10 which provides significant advantages over conventional booths. The shape of the chamber 12 permits ready cleaning thereof and thus reduces the likelihood of contamination if the material being sprayed is changed.

Various modifications may be made without departing from the scope of the invention. For example, the chamber 12 may have a different cross-section. It would be possible to provide different shaped chambers simply by providing different corner sections 22A. Different ducting could be used leading to the outlet port and/or the port could be differently positioned. Ducts such as the domed duct 32 can extend for part or all of the length of the chamber. The duct may be open towards the chamber exit and/or entrance. The duct can also be open circumferentially across the floor of the chamber for part or all of the dome's length. Whilst the above example is a booth for electrostatic powder coating the invention is also applicable to other spray booths usable for example for spray painting and the like.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims:-

1. A spray booth (10), the booth comprising walls (18,20) defining a spraying chamber (12), the chamber (12) being engageable with means for creating reduced pressure in the chamber (12), and one or more locations in the chamber (12) where spraying can take place, characterised in that the booth (10) is arranged such that in use air flows in the chamber (12) from the or at least one of the said locations to the reduced pressure creating means in a spiralling motion.

2. A spray booth according to claim 1, characterised in that the reduced pressure creating means is engageable with the chamber (12) adjacent one end (16) of the chamber.

3. A spray booth according to claim 2, characterised in that the or each spraying locations (24) are preferably located towards the other end (14) of the chamber.

4. A spray booth according to any of the preceding claims, characterised in that the booth (10) comprises means (38) for transporting items (42) to be sprayed through the chamber (12).

5. A spray booth according to claim 4, characterised in that the transporting means comprises a conveyor (38).

6. A spray booth according to claim 5, characterised in that the conveyor (38) extends above the chamber (12) with mounting means (40) extending into the chamber (12).

7. A spray booth according to any of the preceding claims, characterised in that the chamber (12) has an entrance (14) at one end and an exit (16) at the other end.

8. A spray booth according to claim 7, characterised in that the reduced pressure creating means is locatable adjacent the exit (16).

9. A spray booth according to any of the preceding claims, characterised in that the inner walls (18,20) of the chamber are curved.

10. A spray booth according to claim 9, characterised in that substantially all of the inner walls (18,20) of the chamber are inwardly curved.

11. A spray booth according to claim 10, characterised in that the chamber (12) has a substantially constant curved cross-section along its length.

12. A spray booth according to any of the preceding claims, characterised in that the chamber (12) is taller than it is wide.

13. A spray booth according to any of the preceding claims, characterised in that the entrance (14) and/or exit (16) are of smaller cross-section than the remainder of the chamber (12).

14.. A spray booth according to any of the preceding claims, characterised in that the reduced pressure creating means is operable through an outlet (26) from the chamber, and ducting (30,32) is provided extending from the outlet (26) to communicate with a lower part of the chamber (12).

15. A spray booth according to claim 14, characterised in that the ducting (30,32) opens towards the entrance (14) and/or the exit (16), and/or the ducting (30,32) opens circumferentially substantially over the floor of the chamber (12).

16. A spray booth according to any of the preceding claims, characterised in that the chamber (12) is formed of metal, and in a number of sections (22).

17. A spray booth according to any of the preceding claims, characterised in that the spray booth (10) comprises reduced pressure creating means.

18. A spray booth according to claim 17, characterised in that the reduced pressure creating means comprises a fan for sucking air from the chamber (12).

19. A spray booth according to claims 17 or 18, characterised in that the reduced pressure creating means comprises means for recovering sprayed material.

20. A powder coating spray booth, characterised in that the booth (10) is according to any of Claims 1 to 19.