Method of peening and portable peening gun

In a portable peening gun of the type having a hammer supported for axial reciprocation along a rectilinear path and a pneumatic motor for driving the hammer in a first direction along the rectilinear path, the improvement comprising:

• A. an axially reciprocable rod bundle including a plurality of peening rods, each being characterized by an anvil defined at one end thereof for receiving the hammer in impacting engagement as the hammer is driven in said first direction;
• B. means supporting said rod bundle within the path of said hammer including a barrel of a substantially tubular configuration supported in coaxial alignment with the hammer and concentrically related to the rod bundle;
• C. a retainer for confining the plurality of peening rods in closely spaced relation within the bundle, including a retainer of a disk-shaped configuration and characterized by a plurality of uniformly spaced bores extended therethrough for receiving the peening rods;
• D. means for driving said hammer in a second direction, opposite to said first direction, including a helical spring disposed within the barrel in concentric relation with the rod bundle seated against the retainer for continuously urging said bundle in displacement toward said hammer;
• and
• E. means defining a peening surface of a substantially hemispheric configuration at the end of each of said peening rods, opposite said one end, characterized by a radius substantially equal to one-half the thickness of the rod at the end of which the surface is defined.