Some Aspects of Mass Flow Control of Shots in Pneumatic Systems

Author:  V.S. Nadkarni, M.C. Sharma
Source:  The Shot Peener magazine, Vol 10/Issue 3, September 1996
Doc ID:  1996157
Year of Publication:  1996
Abstract:  
Reprinted with permission from the Proceedings of ICSP5 ABSTRACT Mass Flow control of shots is an important factor to attain required and consistent peening intensity. Irregular mass flow of shots in pneumatic systems may give rise to different residual stress pattern in the work pieces of same material and shape, though peened to the same Almen intensity. Experimental investigations were carried out to correlate shot size, nozzle bore and shot feed opening to mixing chamber (orifice diameter), which could provide uniform shot flow at different pressure and air inlet valve opening in manual operated pressure systems. Different designs of mixing chambers were compared. In tubular mixing chambers, concentric tube type mixing chamber gave better performance. Similarly individual orifice plate system was found more convenient than adjustable opening type feed valve. Results showed that in pressure peening system for uniform flow of shots, orifice diameter must be about 0.7 times the nozzle throat diameter. While in syphonic and gravity feed systems this proportion can be still larger. Syphonic systems worked well with orifice diameter 1.25 times the nozzle diameter.