(2) Description of the Prior Art Shot peening is a well-known method of hardening and/or surface treating metal parts, as well as for treating the surface of such parts as turbine blades, for example, in order to improve fatigue life of these turbine blades. Typically, shot peening is accomplished by providing a high speed flow of shot, and supporting a part, such as a turbine blade, in this high speed stream of shot.

SUMMARY OF THE INVENTION The general purpose and object of the present invention is to provide an improved method for shot peening parts such as turbine blades, and more particularly to provide a method that avoids the necessity for propelling the shot at high speed into the part to be treated.

The foregoing object is accomplished by providing a fluidized bed of suspended shot particles which are preferably or relatively hard materials such as ceramic, glass or steel in an enclosure that provides for continuous supply of the fluid to be moved vertically upwardly through such enclosure, and moving the parts or components to be treated through these suspended particles at a speed sufficient to cause compression at the surface of the parts as a result of the parts striking the suspended particles.

This object is accomplished with the present invention by providing a fluidized bed of suspended particles of relatively hard material in an enclosure that provides for a continuous supply of fluid moving vertically upwardly through the enclosure to support the articles in the fluidized bed, and passing the parts to be treated through these suspended particles at a speed sufficient to cause compression at the surface of the parts as the parts strike the suspended particles.

BRIEF DESCRIPTION OF THE DRAWING A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawing and wherein: FIG. 1 shows in vertical section, an apparatus capable of practicing the present invention, which apparatus provides one possible environment for the method of the present invention and is illustrated to show one apparatus capable of establishing a fluidized bed of particles in accordance with the present invention.

FIG. 2 is a view similar to FIG. 1, but taken on the line 2,2 of FIG. 1.

FIG. 3 is a view similar to FIG. 1, but illustrating an alternative embodiment of the present invention.

FIG. 4 is a view similar to FIG. 2, but showing the alternative embodiment of FIG. 3 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in greater detail, FIG. 1 shows one embodiment. An enclosure 10 provides an enclosed space in which a fluidized bed is created with the medium comprising spherical particles. A blower 12 communicates with an opening at the lower end of the enclosure 10 where a screen 14 is provided to support the particles when the blower is turned off. The enclosure 10 further includes an air outlet or exhaust vent 16 at its upper end, and in operation, the blower provides sufficient flow of air or fluid under pressure to support the various particles in the enclosure 10, and to thereby create a fluidized bed of relatively hard, ceramic, glass or steel particles in the interior 20 of the enclosure.

These particles may comprise any suitable material and are preferably of spherical shape such as the shot used in shot peening in the process of cold working metal parts to increase the fatigue life of such parts for example. The present invention is particularly well suited to treating the surfaces of metal turbine blades, and these turbine blades or parts 18,18

are provided on spindles 22,22 which spindles are in turn provided on a rotating turret 24 that is supported for rotation on a horizontal axis 26 by a hub structure 28 provided in the side wall 10a of the enclosure 10.

It will be appreciated that although the parts 22,22 shown in the drawings are longitudinally extending turbine blades of the type provided in present day aircraft engines, that these parts may also comprise other components which are to be surface treated for any purpose. It should also be noted that the shot material provided in the fluidized bed in the form of glass, ceramic or steel spheres may also comprise other suitable material, which material need only be hard enough to so treat the surface of the part moved or passed through the fluidized bed as to achieve the desired result and to enhance the characteristics of the surface of such parts.

The blower 12 is preferably driven by an electric motor Mi and comprises a conventional blower of a sufficient horsepower to generate the air flow required to establish a fluidized bed as set forth above.

A second motor M2 is provided as shown in FIG. 1 to an inner shaft 30 which is provided within the shaft associated with the hub 28, and which in turn drives a sun gear provided inside the rotating turret 24. The sun gear drives several planetary gears 34 associated with the spindles 22 described particularly. Each spindle includes a suitable clamping device for supporting a part to be processed in accordance with the present invention.

It will be apparent that each of the four spindles shown in FIG. 2 are similarly driven by associated planetary gears from the sun gear 32.

A third motor M3 is provided for rotating the hub structure indicated generally at 28, and for rotating the turret 24. These motors M2 and M3 are preferably of the variable speed drive type so as to achieve a desired relative rotation as between the rotation of each turbine or part 18 on its own axis and on the horizontal axis 26 of the turret. As shown in FIG. 2, it may be desirable to rotate the turret in one direction as indicated by the arrow 36 in FIG. 2 while each of the spindles are in turn rotated in the same direction as indicated generally by the arrows 38,38 in FIG. 2.

Turning now to a detailed description of FIGS. 3 and 4, an alternative version of the present invention is there shown wherein an additional degree of freedom is provided for movement of the work piece or turbine blade about an axis oriented perpendicular that blade, and which axis is in turn rotated about the central axis of the turret itself. Whereas the first above-described embodiment illustrates movement of the workpiece about an axis parallel to the axis of the turret, the present invention provides

a mechanism for supporting the workpiece in a chuck that is mounted for rotation movement on an axis oriented generally radially with respect to the turret or turntable axis. Here again, a drive motor is provided for the turret, and the only difference between this alternative embodiment and the first above-described embodiment resides in the right angle drive provided in place of the location for the work piece chuck or holder in the first above- described embodiment of the present invention.

Referring more particularly to a comparison of FIGS. 3 and 4, it will be seen that the individual work pieces or blades being treated can be rotated on their individual blade axes as a result of hydraulic motors provided on the axes of the individual spindles all in accordance with the individual support for the blades and their spindles in the previous embodiment. However, it will also apparent that the radially oriented drive shafts 100 in FIGS. 3 and 4 also allows rotation of these spindles on axes oriented radially with respect to the turret axis itself. This swinging motion created by this mechanism represents an improvement in the embodiment of FIGS. 3 and 4 not present in the embodiment of FIGS. 1 and 2. Rotary actuators are provided in the turret for achieving this rotation of the spindles and their work pieces on said radial axes in order to achieve this additional degree of freedom of movement for the work piece or part in the fluidized bed. The version of FIGS. 3 and 4 is otherwise similar to that shown in FIGS.

1 and 2, and therefor no detailed description of the common features is deemed necessary.