The exhaust power e 3 of the rear chamber in stroke stage is
e 3 ¼ p qk A h s qh ¼
p 2 þ p 3
2
A h s qh
ð11:15Þ
where
p qk Average pressure of rear chamber in sliding stage;
s qh Inertial sliding length of piston in stroke stage.
The exhaust resistance work of the front chamber in stroke stage is
e 4 ¼ p 4 A q s bq
ð11:16Þ
where
p 4 Exhaust residual pressure of front chamber in stroke stage;
A q Working area of piston front end;
s bq Inertial sliding length of piston in stroke stage.
In stroke stage, the compression power e 5 of the front chamber is calculated
according to the adiabatic state, and the specific calculation method is the same as
e 2 . The intake power e 6 of the front chamber in stroke stage is
e 6 ¼
p
0
6 þ p 6
2
A q s jq
ð11:17Þ
where
p 6 , p
0
6 Loop pressure, p 6 ¼ p 1 ;
s jq
Length of front chamber.
According to the same method, the pressure work of the front chamber and the
resistance work of the rear chamber can be calculated.
After calculating the impact energy of the impactor, the final impact velocity of
the piston can be calculated from the kinetic energy formula, that is
v ¼
2eg
G k
1=2
ð11:18Þ
where
G k Piston weight;
g Gravity acceleration;
e
Piston impact energy.
216
11 Pneumatic Down-the-Hole Hammer