with check valve
for pressure-dependent sequence control
Sequence valves are used in power workholding circuits for pressure-dependent sequence control. The compact size allows mounting directly to the fixture, requiring only one pressure line from the power unit to the fixture for single-acting cylinders.
The sequence valves are available with pipe thread G1/4 or manifold-mounting connection for drilled channels.
Several sequence valves can be manifold mounted together to form a battery with only one common P-line.
with adjustable switching time
This sequence valve is used in hydraulic fixtures to operate individual clamping cylinders or entire subassemblies with an adjustable time delay.
Normal sequence valves open without delay, if the adjusted switching pressure is exceeded.
Sometimes it is necessary to slow down the switching sequence for functional reasons. For this reason, this sequence valve does not open pressure-dependently, but by the adjustable stroke of a control piston.
A poppet valve is built into the housing, which can be opened by the hydraulically-operated control piston.
When pressure is applied to port P, hydraulic oil flows through an orifice check valve to the control piston. Since the piston stroke is relatively long, it takes a few seconds for the control piston to open the poppet valve. The delay time depends on the piston stroke, which is limited by the adjusting screw.
The workpiece is to be positioned and clamped in the fixture with hydraulic clamping cylinders.
Hydraulic circuit diagram for a sequence control of 5 single-acting clamping cylinders.
1. Cylinder 1 moves without pressure against the stop.
2. Oil pressure increases up to 160 bar.
3. After the adjusted switching time the sequence
valve opens and cylinder 2 moves almost without pressure against the stop.
In the process cylinder 1 becomes again nearly pressureless.
4. The oil pressure at both cylinders increases up to 160 bar.