In the paper, the authors established a calculating model aiming at a given penetration depth of a wedged bit under dynamic loading,and investigated into the development of the fracture area by means of dynamic finite element method.

The technology and design of one-step molding bore bit;

The results show that the microstructure of new type bainite steel bore bit is bainite ferrite (BF) and retained austenite and has good strength-toughness, wear resistance and has higher tempering resistance.

The warm extrusion forming process and the die for bore bit were analyzed,It is fornd that the main reactor of die & in-die were fractured is forming pressure,structure & manufacture of the die and forming machine etc,and some related measures was tabed to improve using age of die.

The paper discusses the surface boronization method and technology used in the experimental research of hard alloy bits It has a positive effect on the improvement of hard alloy bit body surface strength, wearability and service lif

Based on the analysis of air hammer bit,the present situation of research on mechanics,mechanism of bit and rock mutual impedance,statics,dynamics,hydraulics and the usage of computer simulation on bit are introduced.