AN AUTO-FEED DEVICE FOR FEEDING MEDIA TO BLASTING MACHINE

Abstract

A device for continuously feeding media from an unpressurised container to a pressurised chamber without depressurising the chamber is described. The device comprises a cylinder having two chambers defined by a top wall, and bottom wall, and a dividing wall intermediate the top and the base walls. The top wall comprises an inlet aperture for inlet of media and a pressure equalisation aperture. The dividing wall comprises an inlet aperture for receipt of media from the first chamber and a pressure equalisation aperture in fluid communication with a first pressure equalisation conduit that extends from the second aperture to a top of the first chamber. The bottom wall comprises an inlet aperture for supply of media to the blasting machine and a pressure equalisation aperture in fluid communication with a second pressure equalisation conduit that extends from the pressure equalisation aperture to a top of the second chamber. Closure means associated with the inlet and pressure equalisation apertures in the top, dividing and bottom walls, are provided, each closure means being adapted to open and close the apertures in sequence in which the pressure equalisation aperture is opened prior to the inlet aperture aperture.

Claims

1. A device (1) for continuously feeding media from a first environment having a first pressure to a second environment having a second pressure without substantially altering the pressure in the second environment, the device comprising: a cylinder having two chambers defined by a top wall (3), and bottom wall (4), and a dividing wall (5) intermediate the top and the base walls, the top wall (3) comprising an inlet aperture (10) for inlet of media and a pressure equalisation aperture, the dividing wall (5) comprising an inlet aperture (20) for receipt of media from the first chamber and a pressure equalisation aperture (21) in fluid communication with a first pressure equalisation conduit (27) that extends from the second aperture to a top of the first chamber (6), the bottom wall comprising an inlet aperture (30) for supply of media to the blasting machine and a pressure equalisation aperture (31) in fluid communication with a second pressure equalisation conduit (37) that extends from the pressure equalisation aperture to a top of the second chamber (7), a first closure means associated with the inlet aperture (10) in the top wall (3); a second closure means for the inlet and pressure equalisation apertures (20, 21) in the dividing wall (5) and adapted to open and close the apertures in sequence in which the pressure equalisation aperture is opened prior to the inlet aperture, and a third closure means for the inlet and pressure equalisation apertures (30, 31) in the bottom wall (4) and adapted to open and close the apertures in sequence in which the pressure equalisation aperture is opened prior to the inlet aperture aperture.

2. A device as claimed in claim 1 including actuation means for the first second and third closure means, the actuation means configured to actuate the closure means so that the first and third closure means are actuated to close apertures in the top and bottom walls simultaneously with the second closure means being actuated to open the apertures in the dividing wall.

3. A device as claimed in claim 1 in which one or both of the closure means comprises an actuation rod (32, 22) that is located at along a part of its length within a pressure equalisation conduit (37, 27).

4. A device as claimed in claim 3 in which the closure means comprises a closure disposed on the end of an actuation rod, in which the closure and actuation rod are disposed within the device such that raising of the actuation rod brings the closure into engagement with an aperture from beneath the aperture.

5. A device as claimed in claim 4 in which the closure means for the inlet and pressure equalisation apertures in the dividing wall comprises two closures (23, 25) operatively connected to a first actuation rod (22), wherein the first actuation rod is mounted within the first pressure equalisation conduit, in which the first actuation rod (22) optionally extends through the top wall (3), and the pressure equalisation aperture (21) in the dividing wall (5) and projects into the second chamber, and in which the two closures (23, 25) are optionally operatively connected to the first actuation rod beneath the dividing wall.

6. A device as claimed in claim 4 in which the closure means for the inlet and pressure equalisation apertures in the bottom wall comprises two closures (33, 35) operatively connected to a second actuation rod (32), wherein the second actuation rod is mounted within the second pressure equalisation conduit, in which the second actuation rod (32) optionally extends through the top wall, the dividing wall, and the pressure equalisation aperture (31) in the bottom wall (4) and projects into the second chamber, and in which the two closures (33, 35) are optionally operatively connected to the second actuation rod beneath the bottom wall.

7. A device as claimed in claim 4 in which the closures (23, 25, 33, 35) comprise conical members that engage the apertures from beneath.

8. A device as claimed in claim 1 and including an inlet chamber (8) above the first chamber (6) for directing media from the first environment to the inlet aperture of the top wall.

9. A device as claimed in claim 1 including a delivery chamber (9) disposed beneath the second chamber (7) for receiving media from the second chamber and directing the received media to the second environment.

10. A device as claimed in claim 1 in which the second environment is a pressurised tank of a blasting machine or a mixing chamber of a blasting machine or a mixing chamber of a blasting machine.

11. A blasting machine (1) of the type having a pressurised tank for media, the machine comprising: a pressurised tank for media (51); a dosing device (52) adapted to receive media from the pressurised tank and dose the media into a supply of compressed air (53); a nozzle (55) adapted to receive the mixture of media and compressed air and direct the mixture at a surface to be treated; and a device (1) according to any of claims 1 to 11 in which the first environment is an unpressurised container or hopper and the second environment is the pressurised tank.

12. A blasting machine (50) comprising: a tank (51) for media; a mixing chamber (59) for mixing media with compressed fluid; a dosing device (58) adapted to receive media from the tank and dose the media into the mixing chamber; a nozzle (55) adapted to receive the mixture of media and compressed fluid and direct the mixture at a surface to be treated; wherein the dosing device (58) comprises a device according to any of claims 1 to 11 in which the first environment is the tank for media and the second environment is the mixing chamber.

13. A method for continuously feeding media from a first environment having a first pressure to a second environment having a second pressure without substantially altering the pressure in the second environment, which method employs a device of claim 1, the method comprising the steps of: actuating the closure in the top wall to open the aperture and allow a dose of media fall from the first environment into the first chamber, wherein the inlet and pressure equalisation apertures in the dividing wall are both closed by the closure means and in which the pressure in the first chamber is ambient pressure; actuating the closure in the top wall to close the aperture; actuating the closure means for the inlet and pressure equalisation apertures in the dividing wall to open the apertures in sequence with the pressure equalisation aperture being opened prior to the media inlet aperture, whereby the pressure in the second chamber is equalised with the pressure in the first chamber just prior to the dose of media in the first chamber falling into the second chamber; actuating the closure means for the inlet and pressure equalisation apertures in the dividing wall to close the apertures; and actuating the closure means for the inlet and pressure equalisation apertures in the bottom wall to open the apertures in sequence with the pressure equalisation aperture being opened prior to the media inlet aperture, whereby the pressure in the second chamber is equalised with the pressure in the pressurised chamber just prior to the dose of media in the second chamber falling into the second environment.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0065] The invention will be more clearly understood from the following description of some embodiments thereof, with reference to the accompanying drawings, in which:

[0066] FIG. 1 a sectional elevational view of an auto-feed device according to the invention, shown with both chambers empty;

[0067] FIG. 2 is a detailed view of the auto-feed device of FIG. 1 showing the inlet aperture in the top and bottom wall closed, and the inlet aperture in the dividing wall open;

[0068] FIG. 3 a sectional elevational view of an auto-feed device of FIG. 1, shown with the first chamber charged with a dose of media; and the inlet aperture in the dividing wall closed and the pressure equalisation conduit in the dividing wall open to allow pressure equalisation between the first and second chambers;

[0069] FIG. 4 is a detailed view of the auto-feed device of FIG. 3;

[0070] FIG. 5 is detailed view of the auto-feed device of FIG. 3 shown from a different angle, and showing the aperture in the dividing wall open and the apertures in the top and bottom walls closed;

[0071] FIG. 6 a sectional elevational view of the auto-feed device of FIG. 1, shown with the first chamber empty and the second chamber charged with media, the inlet aperture in the dividing wall open, the inlet aperture in the bottom wall closed, and the pressure equalisation aperture in the bottom wall open;

[0072] FIG. 7 is a detailed view of the auto-feed device of FIG. 6, showing the dose of media in the second chamber and a dose of media in the inlet chamber above the first chamber;

[0073] FIG. 8 is a detailed view of the auto-feed device of FIG. 6, showing the apertures in the dividing wall closed and pressure equalisation aperture in the bottom wall open to equalise pressure between the second chamber and outlet and inlet aperture in the bottom wall to allow the dose of media fall into the outlet;

[0074] FIG. 9 is a sectional elevational view of the auto-feed device of FIG. 1, showing the inlet aperture in the top wall open and a dose of media in the first chamber, and the inlet aperture in the bottom wall open and a dose of media in the outlet;

[0075] FIG. 10 is an illustration of a blasting system comprising a blasting machine, a hopper for media and a device according to the invention; and

[0076] FIG. 11 is an illustration of a blasting machine which employs a device according to the invention as a dosing device.

DETAILED DESCRIPTION OF THE INVENTION

[0077] Referring to the drawings, and initially to FIGS. 1 and 2, there is illustrated a device for continuously feeding media from an unpressurised container to a pressurised chamber, indicated generally by the reference numeral 1. In this case, the device is an auto-feed device for feeding media from a hopper (not shown) to a pressurised tank of a blasting machine (not shown) of the type described in PCT/EP2007/002421. The device 1 comprises a generally cylindrical body 2 having a top wall 3, a bottom wall 4 and a dividing wall 5, in which the top wall 3 and dividing wall 5 define a first chamber 6 and the dividing wall 5 and bottom wall 4 define a second chamber 7. An inlet chamber 8 is provided above the first chamber, and is adapted to engage an outlet of the hopper. An outlet chamber 9 is provided below the second chamber, and in use is adapted to sealingly engage with an inlet of the pressurised tank of the blasting machine.

[0078] Referring particularly to FIG. 2, the top wall 3 includes a media inlet aperture 10 and a pressure equalisation aperture 11 that remains open, and a closure means that can be actuated to open and close the aperture 10, the closure means comprising an actuation rod 12 that projects through the pressure equalisation aperture 11 in the top wall 3, a transverse arm 14 and a conical closure member 15 mounted to the transverse arm by means of a helical spring 16.

[0079] Referring particularly to FIGS. 1 and 7, the dividing wall 5 includes a media inlet aperture 20 and a pressure equalisation aperture 21, and a closure means that can be actuated to open and close the apertures 20 and 21 in sequence, the closure means comprising an actuation rod 22, a first conical closure member 23 mounted to the base of the rod 22, a transverse arm 24 and a second conical closure member 25 mounted to the transverse arm by means of a helical spring 26. A pressure equalisation conduit 27 is provided for providing fluid communication from the second chamber 7 to a top of the first chamber 6 via an aperture 28 in the conduit 27. The pressure equalisation conduit 27 extends through the top wall 3, and the actuation rod 22 is mounted in the pressure equalisation conduit. A seal (not shown) is mounted in a top of the pressure equalisation conduit allow movement of the actuation rod without a change of pressure in the conduit.

[0080] Referring particularly to FIGS. 1 and 2, the bottom wall 4 includes a media inlet aperture 30 and a pressure equalisation aperture 31, and a closure means that can be actuated to open and close the apertures 30 and 31 in sequence, the closure means comprising an actuation rod 32, a first conical closure member 33 mounted to the base of the rod 32, a transverse arm 34 and a second conical closure member 35 mounted to the transverse arm by means of a helical spring 36. A pressure equalisation conduit 37 is provided for providing fluid communication from the third chamber 9 to a top of the second chamber 7 via an aperture 38 in the conduit 37. The pressure equalisation conduit 37 extends through the dividing wall 5 and the top wall 3, and the actuation rod 32 is mounted in the pressure equalisation conduit. A seal (not shown) is mounted in a top of the pressure equalisation conduit allow movement of the actuation rod without a change of pressure in the conduit.

[0081] In practice, the top, dividing and bottom walls will have a generally concave shape to ensure that media falls towards the respective inlet apertures.

[0082] An important aspect of the present invention is the equalisation of pressure between chambers prior to transfer of media from one chamber to another. Without pressure equalisation, the transfer of media is not possible. The inlet chamber located above the first chamber will generally always be at ambient pressure, and the outlet chamber located below the second chamber (which in the above embodiment is in fluid communication with the pressurised media tank) will always be pressurised (i.e. a pressure of X to Y). Thus, when the first chamber contains a dose of media, it will be at ambient pressure and the second chamber will be pressurised. In order to transfer media from the first chamber to the second chamber, the pressure equalisation aperture 21 in the dividing wall 5 needs to be opened while the media inlet aperture 20 is still closed (as in FIGS. 3 and 4) to allow equalisation of pressure between the two chambers. The pressure equalisation conduit 27 ensures that the media in the first chamber is not unduly disturbed during pressure equalisation, by the provision of the aperture 28 in the conduit 27 in an upper part of the chamber, above the level of the media. Once pressure is equalised (which in practice will occur almost instantaneously), the inlet aperture is opened to allow media fall into the second chamber 7.

[0083] Thus, the closure means for the apertures in the top, bottom and dividing walls need to ensure that the apertures open and close in sequence, with the pressure equalisation aperture opening first and the media inlet aperture opening afterwards, in practice immediately afterwards. This achieved by employing an actuating rod with two closures operatively connected to the rod, a first closure for the pressure equalisation aperture which is fixed to the rod for movement therewith, and a second closure for the inlet aperture which is fixed to the rod by means of a lateral arm, and is fixed to the arm by means of a resiliently deformable member that is biased into an extended position, for example a spring such as a helical spring, which allows a relative movement between the rod and the closure. Thus, when both closures are engaged with their respective apertures, downward movement of the rod will move the first closure out of engagement with the pressure equalisation aperture, whereas the second closure will remain in engagement with the inlet aperture due to the biasing effect of the spring until the spring is fully extended at which point further downward movement will open the inlet aperture. In this manner, a temporal and sequential opening of the apertures is achieved.

[0084] The device also includes control means for controlling the closure means associated with the top, dividing and bottom walls. Various control means may be employed, including a cam mechanism or motors controlled by a processor, the details and construction would be known to a person skilled in the art and which will not be described in more detail herein. The sequence of opening and closing of the closures means associated with the three walls is generally as follows:

[0085] Stage 1: at a start of the process, the closures associated with the top and bottom walls will be closed and the closures associated with the dividing wall will be open. In this configuration, the first and second chambers will be unpressurised. Media is located in the inlet chamber above the first chamber (FIGS. 1 and 2).

[0086] Stage 2: the closures associated with the dividing wall will be closed first, and the closures associated with the top and bottom walls will then be opened. In this configuration, the first chamber will be unpressurised, and the second chamber pressurised. Media will fall into the first chamber (FIGS. 3 and 4).

[0087] Stage 3: the closures associated with the top and bottom walls will be closed first, and the closures associated with the dividing wall will be opened second. In this configuration, the first and second chambers will be unpressurised and the media will fall into the second chamber (FIGS. 5, 6 and 7).

[0088] Stage 4: the closures associated with the dividing wall will be closed first, and the closures associated with the top and bottom walls will be opened second. The second chamber will be pressurised prior to the dose of media falling into the outlet chamber. Simultaneously, a dose of media will fall from the inlet chamber into the first chamber, both of which will be unpressurised (FIGS. 8 and 9).

[0089] Repeating these steps in sequence will enable a continuous feeding of media from the unpressurised container (i.e. hopper) to the pressurised tank of the blasting machine without compromising the operating pressure in the tank.

[0090] Referring to FIG. 10, there is illustrated a blasting system according to the invention and indicated generally by the reference numeral 50, and comprising a blasting machine having a pressurised media tank 51, dosing device and mixing chamber 52, pressurised fluid line 53 feeding pressurised air into the mixing chamber 52, pressurised media supply line 54 leading to a nozzle 55. A pressure equalisation conduit (not shown) is provided between the tank 52 and the mixing chamber 52. A hopper 56 is provided for containing media, the hopper having an outlet 57 that feeds media into an auto-feeding device of the invention 58. In use, media is continuously fed into the auto-feed device 58 from the hopper 56, and the auto-feed device feeds doses of media into the pressurised media tank 51 without any substantial pressure drop in the tank, then enabling the blasting machine to continue operating while the tank is being filled.

[0091] Referring to FIG. 11, an alternative embodiment of the invention is described in which parts similar to that described with reference to the previous embodiment are assigned the same reference numerals. In this embodiment, the auto-feed device of the invention is employed as a dosing device for the blasting machine, to feed media from an unpressurised hopper 56 into a mixing chamber 59. In use, the device of the invention acts as a dosing and metering device for dosing media from the hopper 56 into the pressurised mixing chamber 59 of the blasting machine. The rate of dosing of the media may be controlled by altering the timing of the opening and closing of the apertures to speed up or slow down the dosing rate as is required.

[0092] The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail without departing from the spirit of the invention.