Patent Application
20090095043
This application relates to a shot peening tool which has a conformable forward surface such that it can conform to a local surface on a part to be shot peened.
Shot peening is a well-known process used to impart a layer of residual compressive stresses onto metals. The process includes a plurality of hard elements that are directed at a high rate of speed against a surface to be treated for various reasons. Typically, steel shot is blasted at a metal surface by a jet of compressed air, so that the steel shot impacts the target piece of metal. Another method for peening uses a vibrating surface to excite ball bearings to impact the target surface. One type of peening apparatus includes a vibrating surface and a number of projectiles that are directed towards the target piece. The apparatus also includes a rigid structure for keeping each projectile captive in the self-contained peening apparatus. However, peening is performed in a space that is adapted for recovering the steel shot that rebounds after impact with the target.
One known use of shot peening equipment is to repair damaged surfaces on various components, such as gas turbine engine components. The shot peening operation can be an early step in the repair of gas turbine engine turbine blades, as an example. Shot peening can also be used as a post-repair treatment to damaged surfaces. After a damaged surface has been repaired by blending, machining, or other means of material removal; shot peening can be used to restore compressive residual stresses on the target surface. This is typically done to increase the fatigue life of a gas turbine engine component.
When these components are repaired, the shot peening is directed toward the surfaces to be repaired. Surfaces that do not require shot peening must be protected from the peening process. Masking is used to protect these surfaces from peening. Two typical types of masking are used: tape or pre-fabricated shapes designed to conform to specific areas of the component. The components can have complex surface areas that are difficult to shot peen or to mask. Complex maskings are developed to protect the areas surrounding the surfaces to be repaired, and to prevent the shot peening elements from becoming entrapped within small passages or openings of the component. The complex maskings are typically developed for specific areas and cannot be used in other areas of a component nor on different components. The development of complex masking or the application of masking tape to complex surfaces can be time consuming.
If a component requires repair only in a localized area, the entire component typically undergoes masking to protect adjacent and other unpeened areas. If the damage occurs during or after the repair process, the subsequent masking and shot peening required can disrupt the normal production flow in the repair station. The subsequent peening operation can also increase the chances of component damage, unintentional peening in unpeened areas, and delays in delivery schedule.
In a disclosed embodiment of this invention, a shot peening tool has a forward surface made of a material that will conform to the outer surface of a localized area of a component to be repaired.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
The conformable tooling portion 26 may be formed of an appropriate rubber, plastic, wax, polymer, plaster, alginate, or silicone material that can be conformed to the outer surface of the localized area of the component 28. Of course, other conformable materials can be used.
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While embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
