Control-cage, a centrifugal shot-blasting device, and a centrifugal shot-blasting device for throwing abrasive grains

Abstract

A control-cage that can concentrate the distribution of shot-blasting media, a centrifugal shot-blasting device using this control-cage, and a centrifugal shot-blasting device for throwing abrasive grains, are provided. This control-cage is used for a centrifugal shot-blasting device that rotates an impeller having a plurality of blades at high speed, and that throws shot-blasting media at an object to be processed through the opening of the control-cage by means of the blades. The control-cage is cylindrically shaped and is placed inside the impeller. The opening of the control-cage is made by cutting out the cylindrical part of it in parallel with its central axis. Also, the opening has a quadrangular shape, and has lateral walls located upstream and downstream of the direction of the rotation of the impeller. The upstream wall is made so that the angle between a plane containing the axis and the plane containing both the axis and the inner edge of the upstream wall is larger than the angle between the plane containing the axis and the plane containing both the axis and the outer edge of the upstream wall when they are measured in the direction opposite to the direction of the rotation of the impeller.

1 . A control-cage used for a centrifugal shot-blasting device that rotates an impeller having a plurality of blades at high speed, and throws shot-blasting media through the opening of the control-cage by means of the blades, which control-cage is cylindrically shaped and is placed inside the impeller, wherein
 the opening of the control-cage is made by cutting out the cylindrical part of it in parallel with its central axis, has a quadrangular shape and lateral walls (an upstream wall and a downstream wall) located upstream and downstream of the direction of the rotation of the impeller, and wherein   the upstream wall is made so that the angle between a plane containing the axis and the plane containing both the axis and the inner edge of the upstream wall is larger than the angle between the plane containing the axis and the plane containing both the axis and the outer edge of the upstream wall when they are measured in the direction opposite the direction of the rotation of the impeller.   
   
   
       2 . The control-cage of  claim 1 , wherein the upstream wall and the downstream wall are parallel to each other. 
   
   
       3 . The control-cage of  claim 1  or  2 , wherein the upstream wall is made so that the wall would be the tangential line of the inner periphery of the control-cage if the control-cage were to be cut radially. 
   
   
       4 . The control-cage of  claim 3 , wherein the downstream wall is made so that the angle between a plane containing the axis and the plane containing both the axis and the inner edge of the downstream wall is larger than the angle between the plane containing the axis and the plane containing both the axis and the outer edge of the downstream wall when they are measured in the direction opposite to the direction of the rotation of the impeller. 
   
   
       5 . The control-cage of  claim 1  or  2 , wherein the downstream wall is made so that the angle between a plane containing the axis and the plane containing both the axis and the inner edge of the downstream wall is larger than the angle between the plane containing the axis and the plane containing both the axis and the outer edge of the downstream wall when they are measured in the direction opposite to the direction of the rotation of the impeller, and wherein the difference between the angles is 0-35 degrees, in which one angle is between the plane containing the axis and the plane containing both the axis and the outer edge of the upstream wall and the other is between the plane containing the axis and the plane containing both the axis and the inner edge of the downstream wall. 
   
   
       6 . A centrifugal shot-blasting device comprising
 a housing,   a driving means that is installed outside of one of the lateral sides of the housing,   an impeller that has a plurality of blades and that is fitted onto the driving shaft of the driving means,   a distributor that is placed inside the impeller, that is concentrically fitted onto the driving shaft and that has almost equally-spaced openings in its circumference,   the control-cage of  claim 1 ,  2 ,  3 ,  4 , or  5 , wherein it is fitted on an inlet that is provided on another lateral side of the housing, and   an inlet tube that is fixed on the housing so as to let shot-blasting media be supplied to the inlet.   
   
   
       7 . The centrifugal shot-blasting device of  claim 6 , wherein
 the impeller comprises   a lateral plate of the driving shaft of the driving means,   a lateral plate that is located on the side of the inlet tube and apart from the lateral plate of the driving shaft at a given distance, and that has an opening at its center that is larger than the circumference of the control-cage, and   a plurality of blades that are radially fixed between the lateral plate on the side of the inlet tube and the lateral plate on the side of the driving shaft.   
   
   
       8 . A centrifugal shot-blasting device for throwing abrasive grains comprising an impeller that can rotate and that has a cylindrical space in its middle, a control-cage that is nearly cylindrical and that is fixed inside the space and that has an exit for abrasive grains on its cylindrical part to discharge the grains, and a distributor that is located inside the control-cage so that it can be rotated together with the impeller, wherein
 the exit for abrasive grains on the control-cage is approximately an elongated slit that has a given width and that is parallel to the central axis of the control-cage, and has an upstream wall that is located upstream of the direction of the rotation of the distributor, and a downstream wall that is located downstream of the direction of the rotation of the distributor, and wherein   the upstream wall is inclined to the direction of the rotation of the distributor at 30-90 degrees to the line that is orthogonal to the central axis and that crosses the inner edge of the upstream wall.   
   
   
       9 . A centrifugal shot-blasting device for throwing abrasive grains comprising an impeller that can rotate and that has a cylindrical space in its middle, a control-cage that is nearly cylindrical and that is fixed inside the space and that has an exit for abrasive grains on its cylindrical part for discharging the grains, and a distributor that is located inside the control-cage so that it can be rotated together with the impeller, wherein
 the exit for abrasive grains on the control-cage is approximately an elongated slit that has a given width and that is parallel to the central axis of the control-cage, and that has an upstream wall that is located upstream of the direction of the rotation of the distributor, and a downstream wall that is located downstream of the direction of rotation of it, and wherein   the upstream wall extends along an almost tangential line of the inner periphery of the control-cage.   
   
   
       10 . The centrifugal shot-blasting device for throwing abrasive grains of  claim 8  or  9 , wherein
 the downstream wall is inclined to the direction of the rotation of the distributor at 30-90 degrees to the line that is orthogonal to the central axis and that crosses the inner edge of the downstream wall.   
   
   
       11 . The centrifugal shot-blasting device for throwing abrasive grains of  claim 8 ,  9 , or  10 , wherein the downstream wall is approximately parallel to the upstream wall. 
   
   
       12 . The centrifugal shot-blasting device for throwing abrasive grains of  claim 8 ,  9 ,  10 , or  11 , wherein the given width of the exit for abrasive grains is determined so that the angle between the line that is orthogonal to the central axis and that crosses the outer edge of the upstream wall and the line that is orthogonal to the central axis and that crosses the inner edge of the downstream wall is 0-35 degrees. 
   
   
       13 . The centrifugal shot-blasting device for throwing abrasive grains of  claim 8  or  9 , wherein the elongated slit of the exit for the abrasive grains includes a quadrangular opening.