Shot Peening Apparatus

Author:  Joseph F. Loersch, James W. Neal
Source:  US Patent 4,432,220
Doc ID:  1981127
Year of Publication:  1981
Abstract:  
In apparatus for shot peening, gravity is used to accelerate uniform sized steel shot, and thereby impart a combination of good surface finish and uniform compressive stresses to workpieces. It is especially useful for finishing gas turbine airfoils. Shot is introduced into the peening enclosure (28) through a gate (40) at near zero velocity. It is then accelerated along a streamline (31) toward the workpiece (18) with uniform velocity. The workpiece, positioned along the streamline, can be manipulated in three rotational modes: oscillatory rotation to uniformly peen contoured surfaces of a workpiece, periodic incremental rotation to peen different sides of a workpiece; and tilting motion to enable peening of shoulders (22). The apparatus is especially suited to peening fragile workpieces such as gas turbine airfoils (18). A diverter plate (44) intercepts the shot stream at times when repositioning of a fragile workpiece is undertaken. Thus, possibly damaging impacts are avoided and steady state operation is able to be promptly resumed.