Calculating Speed & Acceleration of Pneumatic Cylinder

  • Context: Undergrad 
  • Thread starter Thread starter Serj
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Discussion Overview

The discussion revolves around calculating the speed and acceleration of a pneumatic cylinder when air is forced into it from a compressed air tank. Participants explore equations and factors that influence these calculations, including resistance from airtight rings and flow dynamics.

Discussion Character

  • Technical explanation, Mathematical reasoning, Experimental/applied

Main Points Raised

  • One participant suggests that knowing the velocity or volumetric flow rate into the cylinder is essential, indicating that the actual measurement is complicated due to compressibility.
  • Another participant proposes an equation involving the pressure of the compressed air, atmospheric pressure, and resistance force to determine acceleration, linking it to the mass and cross-sectional area of the cylinder.
  • A different viewpoint emphasizes the use of a needle valve on the exhaust port to control the speed of the air cylinder, explaining that this method regulates the rate at which air exits the cylinder.

Areas of Agreement / Disagreement

Participants present multiple approaches to the problem, indicating that there is no consensus on a single method or equation for calculating speed and acceleration. Various factors and techniques are discussed without resolution.

Contextual Notes

Participants mention complexities such as compressibility and resistance forces, which may affect the calculations but are not fully resolved in the discussion.

Serj
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How do you determine how fast a pneumatic cylinder will move when you force air into it with a tank of compressed air. I also need to know how fast it will accelerate. I only need an equation but resistance from the airtight rings must also be included. Thank you.
-Serj
 
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The only way to really know is to know the velocity or the volumetric flow rate into the cylinder. From there it's simply flow divided by the area. The actual measurement of the flow rate is a bit tricky due to compressibility.
 
I think you can solve the problem if you know the pressure of the compressed air (p) , the atmospheric pressure (p_0) and the resistance force(F_f). From the second principle,

[tex]m\cdot a=pS-p_0S-F_f[/tex]

(S is the cross-section area of the cylinder)

If you have the acceleration, with the length and the Galilei's law the final velocity is piece of cake.
 
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The best way to control the speed of a air cylinder is to use a needle valve on the exhaust port. This will control how fast the air exits the cylinder. They make a combination needle valve/check valve just for this purpose. The check valve allows free flow of air into the cylinder the needle valve controls the rate that air exits, thus controling the speed of activation.

For example

These parts are not very expensive on the scale of things.
 
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