A-39
Exercise 6
Electrohydraulics Subject
Stamping machine Title
Understanding a differential circuit Training aims
Understanding how a 3/2-way valve can be used to activate a double-
acting cylinder
Selection of required components
Development and drawing of hydraulic and electrical circuit diagrams
Assembly of control circuit on a profile plate
Commissioning the control circuit
Compiling components lists
Setting pressure values
Complete the worksheet Problem definition
Define the required components
Draw the hydraulic and electrical circuit diagrams
Label the connections
Number the components
Carry out practical assembly of the hydraulic and electrical control
circuits
Commission the control circuit
Compile the components list
TP601 • Festo Didactic
A-40
Exercise 6
Exercise A hydraulic power pack with a very low pump delivery rate is all that is
available to operate a stamping machine. A suitable circuit must be used
to increase the advance-stroke speed. The power pack output is suffi-
cient to allow this.
A flow control valve is installed at a suitable point in the circuit. This re-
duces the flow rate to the cylinder.
Fig. 6/1:
Positional sketch
TP601 • Festo Didactic
A-41
Exercise 6
WORKSHEET
Complete the hydraulic circuit diagram.
Fig. 6/2:
Circuit diagram, hydraulic
Complete the list of hydraulic components.
Qty. Description List of
hydraulical components
TP601 • Festo Didactic
A-42
Exercise 6
Complete the electrical circuit diagram.
Fig. 6/3:
Circuit diagram, electrical
S1 = START pushbutton
S2 = RETURN pushbutton
Complete the list of electrical components.
List of Qty. Description
electrical components
TP601 • Festo Didactic
C-23
Solution 6
Stamping machine
Fig.6/1:
Circuit diagram,
hydraulic
Fig.6/2:
Circuit diagram,
electrical
S1 = START pushbutton
S2 = RETURN pushbutton
TP601 • Festo Didactic
C-24
Solution 6
Solution description A differential circuit is only possible using cylinders with a single-ended
piston rod and is intended to increase speed in the forward stroke, whilst
pressure is applied to both piston surfaces. Due to the difference in
surface areas, a differential force is created, which causes the piston
rod to advance. The oil displaced on the piston rod side is fed to the
large piston side. The active surface area for the pressing force corre-
sponds to the piston rod surface area. This is why the pressing force is
less in the case of increased advancing speed than if pressure is
applied to a single-sided piston surface.
The solenoid coil 1Y of the 3/2-way valve is actuated via the START
button S1. The piston rod advances using the recirculated oil. If the
RETURN STROKE button S2 is pressed, 1Y is de-energised, the 3/2-
way valve reverses by means of spring force and the piston rod retracts.
The flow control valve is used to represent a hydraulic power unit with
reduced pump delivery. The effect of the differential circuit is thus more
clearly identifiable.
The "Practical assembly, hydraulic" drawing shows a 4/2-way solenoid
valve instead of the 3/2-way valve.
TP601 • Festo Didactic
C-25
Solution 6
Fig.6/3:
Practical assembly,
hydraulic
Item no. Qty. Description Components list,
hydraulic
0Z1 1 Hydraulic power pack, 2 l/min
0Z2 1 Pressure gauge
0V1 1 Pressure relief valve
0V2 1 2-way flow control valve
1V 1 4/2-way solenoid valve
1A 1 Cylinder, 16/10/200
- 2 Branch tee
- 7 Hose line with quick-release coupling, 600 and 1000
TP601 • Festo Didactic
C-26
Solution 6
The following settings must be made:
Pump safety valve 0Z1 to 6 MPa (60 bar)
Pressure relief valve 0V1 to 5 MPa (50 bar)
Fig.6/4
Practical assembly,
hydraulic
S1 = START pushbutton
S2 = RETURN pushbutton
Components list, Qty. Description
electrical
1 Relay, 3-fold
1 Signal input unit, electrical
1 Indicator and distributor panel, electrical
1 Cable set, universal with safety plugs
1 Electrical power supply unit, 24V
TP601 • Festo Didactic
