for single and double acting cylinders
with fixed intensification volume or continuous redelivery
Hydraulic intensifiers convert a hydraulic pressure on the primary side (input) into a higher pressure on the secondary side (output). This enables the use of the comparatively low pressure of machine tool hydraulics to pressurise a hydraulic cylinder with increased pressure.
The oil quantity to be transmitted is not important for the intensifiers of this data sheet. Only after oil supply of the hydraulic cylinder in the low-pressure range is affected, the piston of intensification will be activated according to its specification by an external valve control or by an integrated switching function.
The intensification volume of intensifiers is 21 cm³. This is the reason why no hydraulic element, which functions only with high pressure, e.g. hydraulic accumulators with a gas-preload pressure of more than 100 bar and an oil absorption exceeding 10 cm³, must be used in the high-pressure range. The intensification volume of 21 cm³ is only used to generate the high-pressure, i.e. the compressibility of the hydraulic oil (1% at a pressure increase of 150 bar) and the increase of volume of the high-pressure hoses (1cm³ per m at a pressure increase of 100 bar) has to be considered.
Complete air bleeding of the hydraulic system is very important.
The high-pressure part should be controlled by a pressure gauge.
An oscillating pump piston, that will be automatically reversed in the end positions by a hydraulically-operated valve, is installed in the intensifier. The ratio of the piston areas corresponds to the intensification ratio.
For unhindered flow in the low-pressure range, the pump piston will be bypassed by means of a bypass-line. A pilot-controlled check valve shuts off the high pressure.
The intensifier can produce extremely high hydraulic pressures. The manufacturer of the system must provide effective safety valves for protection against excessive pressures.
The connection of the intensifier must always be double acting. For oil supply, port R must be depressurised.
Pump piston and valve slide are fit with minimum clearance. In order to permanently secure the function, it is imperative to install a high-pressure filter at the input IN of the intensifier (see hydraulic circuit diagram).
As long as pressure is available at IN, the intensifier has an internal leakage between the ports IN and R.
If no pressure is available at IN, the pressure can drop in the high-pressure area in case of a leakage.
By the installation of a pilot-controlled check valve at port H a pressure drop is avoided (see hydraulic circuit diagram). This applies in particular to uncoupled systems (clamping pallets).
If only single-acting cylinders are connected, a double-acting valve function is required to control the pilot-operated check valves for unclamping (see hydraulic circuit diagram).
An oscillating pump piston, that will be automatically reversed in the end positions by a hydraulically-operated valve, is installed in the intensifier.
The ratio of the piston areas corresponds to the intensification ratio. For unhindered flow in the low-pressure range, the pump piston will be bypassed by means of a bypass-line.
A pilot-controlled check valve shuts off the high pressure.
Accessory: Sequence valve
As soon as pressure is available at port IN the oscillating pump starts working and thereby consumes already a part of the available flowrate. Thus, the clamping time is extended.
By means of the manifold mounting sequence valve, the pump is only switched on when really required. This allows a significant reduction of the clamping time, particularly
• in systems with a relatively small low pressure pump
• if a relatively large volume is to be filled at the high-pressure side.
It is also possible to activate the high pressure only when a certain pressure is reached in the system.
This pneumatic-hydraulic intensifier can be used as a pressure generator where live cables are not possible or suitable, e.g. in hazardous surroundings. Only single-acting cylinders can be connected. The cylinder volume should utilise the stroke volume of the intensifier only up to 60-70% so as to have some reserve left.
When designing fixtures, some features of the air intensifier should be taken into account:
1. Extend cylinder
Intensifiers are liable to release the effective oil volume very quickly within 1 second. The oil speed depends only on the flow rate of the compressed air. This may cause malfunctions in clamping elements where the maximum flow rate is limited (swing clamps, work supports). In those cases a flow control valve must be provided on the oil side.
2. Pressure build-up
After extending the cylinders, pressure build-up is relatively slow, according to the nominal bore of the pneumatic piping and air pressure. At 6 bar the sextuple working volume must be fed, which takes approx. 3 seconds.
For this purpose, the air volume accumulated must first be reduced to a residual pressure below 0.2 bar, before the connected hydraulic cylinders retract. The high-speed vent valve available as an accessory allows for a pressure release time of approx. 2 seconds at an initial pressure of 6 bar.
4. Pressure adjustment
The hydraulic operating pressure can only be adjusted by means of a pressure reducing valve at the pneumatic side.
We recommend our service unit part no. 9511-005.
Important note: The maximum operating pressure on the hydraulic side is determined by the component having the smallest admissible operating pressure. The pneumatic adjustment must be checked by a pressure gauge located on the hydraulic side.
Any minor leak losses are compensated after unclamping by replenishing out of the oil tank. This requires a well vented system and an oil filler screw slightly opened.
General application notes General characteristics of hydraulic equipment