The experiments on several Japanese natural diamond bits

The Paper summarizes the experiment rsults on several natural diamond bits used in Sino-Japan cooperation projects,introduces the types and primary structure parameters,conducts a brief analysis on the adaptability of concentric circles rectangle gear impregnated,multi-step surfaceset and spraying bits and the drilling efficiency in some lithologic formations,and put forward the suggestions on improving powder discharge capability of bits water circulation system based on the problems found during experiments.