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.

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.