(2) Impact frequency
According to the force condition of each stage of piston stroke and return stroke, the
piston stroke time t 1 and return time t 2 can be calculated by kinematics and
dynamics equation, and the formula for calculating impact frequency is obtained as
follows.
f ¼
1
t 1 þ t 2
ð11:19Þ
Because the pressure acting on the piston by stroke and return stroke varies with
time and the law of change is different in different stages of motion, the average
pressure and its acceleration, velocity and time in each stage of motion should be
calculated first, and then the impact frequency should be calculated. In order to
simplify the calculation, the variable acceleration motion of piston under variable
force can be replaced by the uniform acceleration motion under equivalent pressure
according to the principle of equivalent force.
The average equivalent pressure is
p p ¼
e
A k Ds
ð11:20Þ
where,
Ds Actual piston stroke.
The impact frequency is
f ¼
1
1 þ s
p p A k g
2DsG k
1=2
ð11:21Þ
where
s Return stroke time coefficient of piston, generally s ¼ 1:15 $ 1:5.
11.3.4.3 Performance Parameter Linear Equation Method
This method was first proposed by Soviet scholar, because it was found that the
pressure of the back chamber changed linearly when the piston in stroke stage in the
dynamic diagram of the gas pick obtained from the study. On this basis, the
performance parameters of the impactor are calculated, that is the linear equation
method of performance parameters, which is not introduced here.
From the above methods, it can be seen that the traditional methods for analyzing the dynamic process of impact equipment do not take into account the
influence of gas thermodynamics, or modify the influence of gas thermodynamic
11.3 Principle and Parameter Design of Large Diameter …
217
According to the force condition of each stage of piston stroke and return stroke, the
piston stroke time t 1 and return time t 2 can be calculated by kinematics and
dynamics equation, and the formula for calculating impact frequency is obtained as
follows.
f ¼
1
t 1 þ t 2
ð11:19Þ
Because the pressure acting on the piston by stroke and return stroke varies with
time and the law of change is different in different stages of motion, the average
pressure and its acceleration, velocity and time in each stage of motion should be
calculated first, and then the impact frequency should be calculated. In order to
simplify the calculation, the variable acceleration motion of piston under variable
force can be replaced by the uniform acceleration motion under equivalent pressure
according to the principle of equivalent force.
The average equivalent pressure is
p p ¼
e
A k Ds
ð11:20Þ
where,
Ds Actual piston stroke.
The impact frequency is
f ¼
1
1 þ s
p p A k g
2DsG k
1=2
ð11:21Þ
where
s Return stroke time coefficient of piston, generally s ¼ 1:15 $ 1:5.
11.3.4.3 Performance Parameter Linear Equation Method
This method was first proposed by Soviet scholar, because it was found that the
pressure of the back chamber changed linearly when the piston in stroke stage in the
dynamic diagram of the gas pick obtained from the study. On this basis, the
performance parameters of the impactor are calculated, that is the linear equation
method of performance parameters, which is not introduced here.
From the above methods, it can be seen that the traditional methods for analyzing the dynamic process of impact equipment do not take into account the
influence of gas thermodynamics, or modify the influence of gas thermodynamic
11.3 Principle and Parameter Design of Large Diameter …
217