Assignment
You are asked to design a clamp and work station with two clamps. Clamps were independently operated through two 4-inch (diameter) hydraulic cylinders actuated using a directional control valve controlled through a PLC. The cylinders are single acting spring return types and works in coordination with the automation system to achieve the work done. The clamp should exert a force of 300 lbs ± 10% to hold the work piece. This holding force should remain within the tolerances stated above (± 10%) so that the work-piece neither get damaged because of excessive force nor loosens which may cause damage to both the work-piece and the tools.
The directional control valve connects the cylinder inlet port either to the high-pressure side of the system or to the oil return line. Each of the clamp cylinders has a diameter of 4 inch and stroke length of 'x' inches and shall complete the stroke in I' seconds to engage the clamp. The hydraulic fluid used in the system has a specific gravity of 0.82 and kinematic viscosity of 4.31 x 10-4 ft2/s. A standard schedule 40 steel pipe of length V connects the header that connects the two cylinders through the DC valves. Distance between the connection header and the cylinder inlet is negligible. Neglect the power losses in the fittings, valves and bends.
Hydraulic pump of the system will operate only when the cylinders are extending. The system must not operate in critical zone of fluid flow (NR between 2000 to. 4000), you must adjust pipe dimensions to allow the system to operate outside of critical zone. Give rationale for the choice you made.
a) calculate the volume, mass and weight flow rate of the hydraulic fluid in the system when i) one cylinder is extending and ii) when both cylinders are extending
b) compute the head loss in ft.lb/lb between pump outlet and inlet at header. Neglect losses in the header and connecting tubes as the cylinders installed at a very short distance from the header. Ignore entry and exits losses as well.
c) how much energy will be removed from the system by the cylinders, calculate the energy withdrawn from the system for all the possible scenario.
d) what would be pressure drop between pump outlet and header inlet?
e) what would be required system pressure at connection header, ignore the pressure drop between connection header and cylinder inlet?
f) how much energy were added to the fluid by the pump when i) one cylinder was extending and ii) when both were extending at the same time
g) what would happen to the system pressure after the cylinder completes its extension stroke? What measure can you suggest that could eliminate the pressure fluctuations and will ensure proper operations of the clamps per the system requirement?
NB: you must use the spreadsheet uploaded with this assignment to determine the stroke length and time, and length of the pipe for your system.