Work order: Packet roller slide - energy efficient and secured
You should develop the control circuit for a roller slide. Special emphasis should be placed on safety and energy efficiency.
Requirement 1: The lifting cylinder is to hold in the current position even in case of a power failure, that means sagging down should be prevented. Give two possible solutions and discuss the advantages and disadvantages.
Requirement 2: The extension and retraction of the lifting cylinder should be throttled and this should be as energy efficient as possible.
Analyse of the pneumatic diagram:
A1: What is the function of the check valve V1?
A2: What function do the components V14 and V15 have in this circuit?
A3: Which throttle is active here when lifting and retacting the cylinder 1A1?
A4: Calculate the extension force of the lifting cylinder 1A1. Data: cylinder 50/8/500, system pressure 6 bar.
A1: Z1 represents a compressed air storage. If the compressor fails, the compressed air of the accumulator should not escape via the maintenance unit. That´s for check vlave V1.
A2: V13 and V14 are unlockable check valves, also known as stop valves - poppet valves of design. Advantage compared to a 3/5-way valve with with all parts blocked in center position: With these check valves the cylinder remains in its current position even under load and this for a long time. Not so with a 5/3-way valve, which is not 100% tight like almost every slide valves.
A3: The cylinder is intake throttled when extending. Since the load is positive, that means cylinder force"works" against the load , there is no problem with the stick-slip effect.
The retraction of the cylinder works with exhaust air throttling. Here the weight of the workpiece acts as a negative load.
A4: ACyl = π D2/4 = π 502/4 mm2 ≈ 1963,5 mm2
FCyl = p * A * η = 0,6 N/mm2 * 1963,5 mm2 * 0,95 = 1,1192 kN