Numerical Analysis of a Small Pneumatic Hammer Performance Based on Evaluation Method of Friction Force

Table 1

Piston logic and conditions at each stage.

Stages	Piston displacement ()	Velocity ()	Air condition ()	Collision
a				No
b				No
c				No
d				Yes
e				No
f				No

Note., , , represent certain key locations in the piston where the air conditions change at each stage; represents the instantaneous air mass flow rate passing through the front chamber; and represents the instantaneous air mass flow rate passing through the rear chamber, as shown in Figure 1.