Double Pneumatic Cylinder Selection Guide: Five Key Steps from Theory to Practice
The selection of double-Pneumatic cylinder Pneumatic cylinders is a systematic project and is by no means a simple matter of "choosing Pneumatic cylinder diameter based on thrust". A correct selection can ensure the long-term stable and precise operation of the equipment, while an incorrect selection may lead to loss of accuracy, Pneumatic cylinder damage, or even production stagnation. This article will guide you through a clear "five-step method" to scientifically select a double-pneumatic cylinder.
Step 1: Calculate the required thrust and initially determine the Pneumatic cylinder bore
This is the basis for selection. You need to first calculate the theoretical thrust required to drive the load.
Calculate the theoretical thrust (F):
F = (load mass m × acceleration a) + Frictional force f + external force F_external
(Note: If the motion is uniform or the speed is very low, the acceleration term can be ignored.)
Select the load rate (η):
Standard condition (η≤50%):
This is the most commonly used situation, providing sufficient margin for the lifespan and stability of the Pneumatic cylinder.
Low-speed or uniform movement (η≤70%): If the Pneumatic cylinder speed is very slow (<100 mm/s) or it is static pressure maintenance, the load rate can be appropriately increased to select a smaller Pneumatic cylinder diameter, but caution should be exercised.
Calculate the theoretical output force of the Pneumatic cylinder and reverse calculate the Pneumatic cylinder bore:
The theoretical output force of the double-Pneumatic cylinder f_Pneumatic cylinder = P ×A ×2 (where A is the cross-sectional area of the single Pneumatic cylinder)
The required Pneumatic cylinder output force F_ required = F theory / η
Therefore, it can be obtained that A = F_ required/(2 ×P), and then the minimum Pneumatic cylinder diameter D can be calculated.
For example: The required thrust is 300N, the working pressure is 0.5MPa, and the load rate is taken as 0.5.
F_ required = 300N / 0.5 = 600N
A = 600N/(2 ×5 bar ×10) ≈60 mm² (Note: 1MPa=10bar≈10N/mm²)
If D = 2 ×sqrt(60/π) ≈8.74mm, then at least a Pneumatic cylinder with a standard diameter of 10mm should be selected.
Step 2: Check the lateral load and bending moment
This is the core link in the selection of double-Pneumatic cylinder Pneumatic cylinders, which directly affects the guiding accuracy and service life. Although the double-pneumatic cylinder can withstand a certain lateral load, it must not exceed its allowable value.
Method: Based on the Pneumatic cylinder bore you initially selected and the actual stroke, refer to the "Maximum concentrated load" chart of this model of Pneumatic cylinder (as shown in the original figure 5.4-26a).
The actual lateral load that the Pneumatic cylinder bears during operation must be less than the allowable value for the corresponding stroke as shown in the chart. If the limit is exceeded, a larger Pneumatic cylinder diameter or a stronger guiding form (such as guide rod Pneumatic cylinder) must be selected.
Step 3: Verify the kinetic energy and select the buffer type
The piston of the Pneumatic cylinder has kinetic energy at the end of its stroke. If the kinetic energy is too large, it will cause impact, vibration, and damage.
Calculate the kinetic energy (E_k):
E_k = 1/2 ×m ×v²
(m represents the total load mass, and v represents the maximum impact velocity)
Verification: Compare the calculated kinetic energy with the "allowable kinetic energy" value in the Pneumatic cylinder sample (as shown in Figure 5.4-26b of the original text).
Decision
If E_k < the allowable kinetic energy of the standard type, Select the basic type with cushion buffer or adjustable gas buffer.
If E_k is large, a model with a hydraulic buffer (such as the CXSL series) must be selected, as its ability to absorb kinetic energy is 2 to 3 times that of the pneumatic buffer.
Step 4: Consider the installation posture and the extended load
The installation method (horizontal/vertical) and the overhang (l) of the load will generate additional overturning moments, which greatly affect the service life and selection of the Pneumatic cylinder.
As shown in Figure 5.4-27a, the extended load m will generate a moment M = m ×g ×l along the length l.
Method: It is necessary to refer to the dedicated selection diagram provided by the manufacturer (as shown in Figure 5.4-27b of the original text) based on the installation form, stroke, speed, overhang l, and load mass m.
Conclusion: This chart will directly provide the recommended minimum Pneumatic cylinder bore under specific working conditions. For instance, when installed horizontally, with a speed of 400mm/s, a stroke of 30mm, l=40mm, and m=0.2kg, the chart recommends choosing CXSW25 (Pneumatic cylinder bore 25mm) instead of a smaller model.
Step 5: Confirm the series and additional functions
Finally, select the specific series and options based on the aforementioned results:
CXS: Basic type, cushion, or air cushion.
CXSL: Equipped with a hydraulic buffer, it has a strong ability to absorb kinetic energy and is suitable for medium and high-speed applications.
CXSW: Double rod type, more symmetrical structure, better rigidity.
Additional function: Is it necessary to have a magnetic ring (for installing magnetic switches for position detection)? Is it necessary to install accessories (such as feet, flanges, etc.)?
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Double Pneumatic cylinder 12-CXSL32-75-Y69BZ
This model is a typical result of following the above selection process:
Pneumatic cylinder diameter 32mm: It provides sufficient thrust and lateral load resistance, meeting the requirements of most medium-load applications.
CXSL series: Built-in hydraulic buffer, which can effectively absorb the impact at the end of the stroke, allowing for higher working speed, smoother operation, and longer service life.
Stroke 75mm: This falls within the commonly used stroke range and is suitable for most handling and picking operations.
High-precision guidance: The double piston rod structure offers superior bending moment resistance compared to ordinary Pneumatic cylinders, ensuring no rotation during operation and precise positioning.
Thin and compact: Saves installation space and is highly suitable for high-density layouts in automated equipment.
Conclusion: If, after calculation through the above five-step method, you find that you need a thin Pneumatic cylinder with a diameter of around 32mm, which requires good buffering and high-precision guidance, then the 12-CXSL32-75-Y69BZ is undoubtedly a reliable choice that has been fully verified.
Above is the Double Pneumatic Cylinder Selection Guide: Five Key Steps from Theory to Practice content. To learn more related information, visit https://www.joosungauto.com/.
