Method Of And Apparatus For Measuring Intensity Of Peening In Small Hole Diameter Holes

Author:  Metal Improvement Co./Smith, G.
Source:  US Patent 3,695,091
Doc ID:  1972007
Year of Publication:  1972
Abstract:  
The method of measuring intensity of peening in the Almen scale of small diameter holes, such as 0.5 inch or less, consists of a first step of plotting an intensity curve on a reference graph, which intensity curve is proportional to but a fraction of the Almen scale. The intensity curve is plotted by peening, under a predetermined intensity, a number of Almen strips which have been masked to expose only portions of each of the strips so that each strip has an exposed portion differing in width from the others in equal increments of linear measurement and, then, measuring the curvature of each peened strip. Thereafter, peening a portion of an Almen strip which overlies at least one arcuate groove which has chordal dimension equal to the smallest unit width employed to produce the reference graph. After peening the Almen strip in which the same peening apparatus and technique used to peen the holes of the production pieces is utilized, the curvature of the strip is measured. The measurement is plotted on the reference graph to obtain an Almen scale measurement is for a hole size outside of the intensity curve, the measurement is then extrapolated by using the reference graph to achieve an Almen scale measurement. This Almen value then can be compared with the Almen scale peening intensity called for to insure that the peening meets that requirement and continues to meet the Almen intensity during production peening.