Calculation of cylinder force
The pressure of the oil cylinder is determined by the load. The pressure of the physical force is equal to the force divided by the action area (i.e. P = f / s)
if the output force of the oil cylinder is to be calculated, the pressure of the oil cylinder is determined by the load, It can be calculated according to the following formula:
thrust f push of oil cylinder = 3.14 * r * r * P (unit n)
tension f pull of oil cylinder = 3.14 * (R * R-R * r) * P (unit n)
R is the radius of piston (i.e. cylinder barrel) (unit mm)
R is the radius of piston rod (unit mm)
P is the working pressure level (unit MPa)
extended data
the main unit of pressure
A. pressure
international unit: "Newton", abbreviated as "cow", symbol "n"
B. pressure
international unit: "Pascal", abbreviated as "pa", symbol "pa"
converted 1 pa = 1n / m2
1 MPa = 145 psi = 10.2 kgf / cm2 = 10 bar = 9.8 ATM
1 psi = 0.006895 MPa = 0.0703 kg / cm2 = 0.0689 bar = 0.068 ATM
1 bar = 0.1 MPa = 14.503 psi = 1.0197 kg / cm2 = 0.987 ATM
1 atmospheric pressure (at M) = 0.101325 MPa = 14.696 psi = 1.0333 kg / cm2 = 1.0133 bar
1 mmHg = 133.33 PA
200 mm = 20 cm 100 mm = 10 cm 15 MPa = 150 kg / cm2
oil cylinder thrust: 3.14 × ten × 10 area × 150 pressure = 47100kg = 47.1t
cylinder pull: 3.14 ×( ten × 10-5 × 5) Area × 150 pressure = 35325kg = 35.325t
the resistance of oil return is not considered in the above calculation, because you have not provided oil return pressure. But the impact should be small.
for multi section cylinder, the inner diameter area X of outer cylinder is used.
The movement speed of
cylinder is equal to the flow into the cylinder cavity divided by the area used for
. The calculation formula is as follows:
cylinder thrust: (1) F1 = P1 × A
cylinder pull: (2) F2 = P2 × B
extension speed: (3) V1 = Q1 / a
retraction speed: (4) V2 = Q1 / b
where: F1 -- force (thrust) generated in rodless cavity, KGF F2 -- force (tension) generated in rodless cavity, KGF
A, B -- area of rodless cavity and rodless cavity, cm2
D -- inner diameter of cylinder, CM D -- diameter of piston rod, CM
V1 -- extension speed of piston rod, Cm / min V2 -- piston rod retraction speed, cm / min
Q1 -- oil inlet flow rate of cylinder without rod chamber, cm3 / min Q2 -- oil inlet flow rate of cylinder with rod chamber, cm3 / min
[example]
(1) inner diameter of cylinder d = 100 mm, input pressure of cylinder P1 = 160 kgf / cm2, and thrust of cylinder:
F1 = P1 × A=160 × zero point seven eight five × 102 = 12560 (KGF)
(2) oil cylinder inner diameter d = 100 mm, rod diameter d = 70 mm, oil cylinder input pressure P1 = 160 kgf / cm2, its oil cylinder tension is:
F2 = P2 × B= P2 × 0.785(D2-d2)= 160 × 785 (102-72) = 6405.6 (KGF)
(3) the inner diameter of the cylinder d = 100 mm, the flow into the rodless cavity is 80 l / min, and the extension speed of the cylinder is:
V1 = Q1 / a = 80 × 103/0.785 × 102) = 1019.1 (cm / min) = 17cm / s
(4) as above, the retraction speed of cylinder piston is:
V2 = Q1 / b = 80 × 103/〖0.785 ×( 102-72)〗=1998.2cm/min= 33.2cm/S
wall thickness (mm) = pressure (MPA) x
inner diameter (mm) / (2x allowable stress)
where the allowable stress = material yield strength / safety factor.
or
the calorific value of the fuel mass in the cylinder divided by the piston movement distance
to define the force (load) of the hydraulic cylinder is the prerequisite for selecting the existing standard series of hydraulic cylinder procts or designing the hydraulic cylinder by ourselves. The force F of the hydraulic cylinder is closely related to the working nature of the working mechanism driven by the cylinder and the sealing structure of the cylinder. Its calculation is as follows: F = f (FA + FB + FC + FD), where fa - external load resistance (including working load and external friction resistance), resistance load (load opposite to the direction of movement) is +, Exceeding load (load in the same direction of motion) take -; The external friction resistance is equal to the proct of the component force of the moving part perpendicular to the moving direction of the working part and the friction coefficient. FB -- inertia force of hydraulic cylinder ring starting and braking, take + when accelerating, take - when decelerating and take 0 when constant speed. FC -- return oil resistance (resistance caused by back pressure), FC = 0 when the oil has no obstruction to return to the tank, F when the return oil has resistance (back pressure). It is the hydraulic resistance acting on the pressure bearing surface of piston. FD -- seal friction resistance< br /> Fd=f△p(DbDkD+dbdkd) × In equation 106, f is the friction coefficient of the seal. According to different lubrication conditions, f = 0.05 ~ 0.2 can be selected; Δ P is the pressure difference between the two sides of the seal, MPa; D. D is the inner diameter of hydraulic cylinder and piston rod diameter, m; BD and BD are the width of piston and piston rod seal, M; KD and KD are the friction correction coefficients of piston and piston rod seals, k = 0.15 for O-ring, k = 0.25 for lip ring and K = 0.2 for compression ring. The working load is related to the technological purpose and nature of the host machine, and can be calculated by experiments or relevant formulas (such as the cutting force calculation formula of metal cutting machine). The above-mentioned loads may not exist at the same time in each working stage of a working cycle. For example, in the process of starting or braking, there is only inertial load, while in the constant speed stage, there is only external load, and the inertial force FB = 0. For the more complex cycle process, the load can be calculated in stages and plotted on the coordinate diagram (load time cycle diagram) (for example, see Figure 5-17 below), so as to fully understand the maximum load, minimum load and load changes in a work cycle.
P = f / s
the selection of pressure depends on the load size (i.e. f) and equipment type. The assembly space, economic conditions and supply of the actuator should also be considered
in the case of a certain load and low working pressure, it is bound to increase the structural size of the actuator, and for some equipment, the size should be limited. For the fixed size of less limited equipment, the pressure can be lower, and the walking machinery should be higher
extended data:
precautions:
1. The design of hydraulic cylinder should avoid non-standard size as far as possible, and the two ends of hydraulic cylinder should not be fixed when the oil temperature changes greatly
The flange type hydraulic cylinder should not be loaded by bolts, and the flange fixed hydraulic cylinder at the tail can not make the fixed bolts bear bending moment In addition to routine inspection, the connecting screws should be tightened regularly, and the seals should be replaced regularly according to the specific working conditions of the hydraulic equipment Pay attention to the cleaning of working medium, often monitor and pay attention to the working condition of hydraulic cylinder, and observe the working pressure, speed, crawling and vibration Monitor and pay attention to the working condition of the hydraulic cylinder, observe the working pressure, speed, crawling and vibration, keep the hydraulic cylinder clean, and prevent st, lint and dirt from entering the systemif the output force of the oil cylinder is to be calculated, It can be calculated according to the following formula:
let the radius of piston (i.e. cylinder barrel) be r
(unit mm)
the radius of piston rod be r
(unit mm)
pressure level P
(unit MPa)
then
thrust of oil cylinder
F push = 3.14 * r * r * P
(unit n)
pull of oil cylinder
F pull = 3.14 * (R * r * r) * P
(unit n)