single acting with and without spring return
Double-acting block cylinders can be used universally for all hydraulically-operated linear movements.
Single-acting block cylinders can be used for all hydraulically-operated linear movements that do not require a retraction force or where the piston is retracted by an external force.
The double-acting functioning allows a force generation in both axial directions (force to push and to pull). This guarantees a high function safety as well as exactly calculable and repetitive times required for the stroke.
Single acting with spring return
When pressurising the cylinder the piston extends. After pressure relief, the piston is retracted by spring force. The pressure spring must not only overcome the friction forces, but must also supply the hydraulic oil back to the reservoir.
Single acting without spring return
When pressurising the cylinder the piston extends. After pressure relief, the piston must be retracted by an external force. Since no pressure spring is installed, this single-acting block cylinder has the same stroke as the double-acting version with the same length.
Block cylinders have cross holes and/or longitudinal holes for mounting. For mounting of the block cylinders internal threads can be provided instead of the through holes, optionally at the piston rod side or the bottom side.
As an alternative to a support, hydraulic block cylinders can be fitted in the housing with a keyway, which transfers the cylinder forces to the baseplate surface via a key.
data sheet B1.5091 (single acting)
data sheet B1.5094 (double acting)
Connection with pipe thread
Manifold-mounting with O-ring sealing
Manifold-mounting connection K- with 2 mounting holes
Manifold-mounting connection L - with 4 mounting holes
Manifold-mounting connection S- with 4 mounting holes
Manifold-mounting connection B- with 4 mounting holes
Stroke limitation by distance bushing: Economical and quickly supplied intermediate strokes
A distance bushing is inserted on the piston rod side in the standard cylinder with the next largest stroke and fastened inside the housing. That means the piston can no longer complete the extending stroke and the stroke is restricted by this internal stop, dependent on the length of the bushing.
For every end position, the cylinder housing is given a hole with interior thread, into which a high-pressure resistant, interactive proximity sensor can be screwed. The sensor checks the piston of the cylinder directly. It is sealed on the outside with an O-ring. By means of the switching distance between the sensor and the piston, the switching point can be adjusted to 5 mm before the end position. Only the end positions of the block cylinder are checked by the high-pressure resistant sensors.
For a check with commercially available proximity initiators, block cylinders are equipped with a piston rod which passes through the cylinder base. In addition a housing for checking, in which the sensors are adjustably fitted, is flanged on the cylinder base. The sensors are energised by control cams on the piston rod.
The additional housing makes the total length considerably longer but commercially available sensors with M8 x 1 external threads can be used. Because the sensors can be moved, intermediate positions can also be checked.
The stroke end cushioning throttles the flow rate in the last millimetres of the stroke (e.g. 8 mm) and reduces the piston speed and the energy in the end positions. The stroke end cushioning is adjustable and the cushioning effect can be adapted to the corresponding application. In addition, both end positions can be separately adjusted.
Block cylinders with piston rod with external thread can be equipped with a spherical bearing (accessory). Bearing flanges with rod end bearing are available for fixing at the cylinder bottom. Rod end bearings can be screwed and fixed onto the piston rod.
At maximum operating pressure, block cylinders with aluminium housings are restricted to 350 bar and are not suited to abrupt stresses, which occur, for example, with punching and cutting processes. For such applications, block cylinders with bronze housing are suitable. The bronze housings have a high strength and can be used with abrupt stresses, which occur, for example, with punching and cutting processes
Block cylinder of aluminium or steel with guide housing in front, in which a pin is supported. The pin is positively fitted to the piston rod and transfers the hydraulic force to the point of application. All side loads which occur are transferred only to the pin, i.e. the guide housing. The distance of the block cylinder to the effective point allows application in more difficult applications, e.g. welding fixtures
Built-in elements are directly integrated in the fixture body. Such created cylinders can be used as push or pull cylinders.
The built-in elements consist of piston and threaded bushing. The piston is inserted into the location hole of the fixture.
Then the built-in bushing is screwed into the fixture body. The bushing is let-in flush to the housing.
High alloy steel, bronze alloy and special aluminium alloys.
case-hardening steel, hardened
Block cylinders with aluminium or bronze bodies are alternatively also equipped with pistons made of stainless steel.
All block cylinders can be installed in any position.
The maximum piston speed for all series is 0.25 m/s.
Exceptions are the block cylinders B1.542 and the hydraulic block cylinders B1.590. Their piston speed is twice as high with 0.5 m/s.
Fittings suitable for the Whitworth G pipe thread correspond to DIN 2353, screwed plug type B according to DIN 3852 sheet 2 (with sealing edge or soft seal).
For block cylinders with aluminium or bronze housing only fittings with soft seal (elastic seals) must be used.
Important! No additional sealing materials, such as Teflon ribbon, must be used!
If there is a possibility that aggressive cutting lubricants and coolants penetrate through the sintered metal air filter into the cylinder's interior, a vent hose has to be connected and be placed in a protected position.
For further notes and provisions see data sheet A0.110.
ROEMHELD block cylinders do not leak oil when static. When displacing the piston a sealing with minimum leakage is obtained by the double piston sealing.
For the life of the sealing dry operation has to be avoided, so that a residual lubricating film will be tolerated.
Admissible guide values for 1000 double strokes and hydraulic oil HLP 22 are:
Side loads stress the guides for the piston and piston rod of the cylinder and thereby cause a reduction in working life and leakages leading to the destruction of the cylinder. For this reason, side loads should be avoided - especially with single-acting cylinders.
Under no circumstances must the cylinder side load exceed 3 % of the cylinder force at maximum operating pressure (up to 50 mm stroke). In the case of longer strokes please contact us.
In principle, screws of tensile strength 8.8 can be used to secure the block cylinders.
If block cylinders are fastened with screws across the cylinder axis, they must be supported above a specific operating pressure.
Block cylinders: from 160/250 bar
Hydraulic block cylinders: from 100/160 bar
(Use as push cylinder / pull cylinder)
The support only has to be a few millimetres high.
If hydraulic cylinders are operated at high speeds, when the piston hits the stroke end position unimpeded, a high amount of energy is released and must be absorbed by the cylinder housing and the threaded bushing. This can lead to a reduction in the cylinder's working life. This can also result in undesirable effects on the actual function, caused by shaking and noise coming from the knocking.
Reducing the speed helps, of course. If this is not possible, however, it is recommended to use a cylinder with integrated hydraulic stroke end cushioning. In the last few millimetres of the stroke (e.g. 8 mm), this stroke end cushioning forces the hydraulic fluid through a hole or similar. By means of this orifice effect, the flow rate is throttled and the piston speed and the energy in the end positions is thus reduced.
The stroke end cushioning is adjustable and the cushioning effect can be adapted to the corresponding application. In addition, both end positions can be separately adjusted.
A permanent magnet is fixed to the piston, and its magnetic field is detected by a magnetic electronic sensor. With block cylinders, the magnetic sensors are fixed to the outside of the housing in slots running lengthwise.
In order to guarantee perfect functioning, it is recommended to maintain a distance of at least 25 to 30 mm between magnetic sensor and magnetisable components. The function is indeed possible with a smaller distance but this depends highly on the individual circumstances for fitting. Thus ordinary steel bolts can also normally be used for fastening the cylinder. In borderline cases, screws of non-magnetisable steel (e.g. VA screws) can cause an improvement in the magnetic field.
If several block cylinders with magnetic sensors are installed directly adjacent to one another, the magnetic sensors can have a reciprocal influence and malfunctions occur. A magnetisable steel sheet can help, placed between the block cylinders, i.e. magnetic sensors, as a shield.
solenoid: +100 °C
magnetic sensor: + 100 °C
Connecting cable with right angle plug: +90 °C
This has to be considered already when adjusting the magnetic sensors.
For static pistons, the magnetic sensor must always be pushed forward to the piston from the opposite direction.
5 block cylinders operate these core-pullers for the required dimensional accuracy of the complex shaping of this elbow tube with two additional tube connections.
The core-pullers for injection moulding connecting components made out of plastic materials are inserted and retracted by aluminium block cylinders B1.554 for fabrication in exact position.
The exact shaping of the inlet for the later installation of the microphone is made during the injection process by dies, which are operated by aluminium block cylinders with magnetic sensors.
In the figure the core cylinder is located in the main core. The position monitoring supplies the required information about the position of the core pins.
The connection of cylinder and core puller should be effected by means of a coupling pin, because core pullers are usually self-guiding.
If it is impossible to install a block cylinder directly due to force or space restrictions, the block cylinder with spherical bearing might be an alternative.
The figure shows the operation of a slide in a deep-draw mould for a container. The position monitoring supplies the required information about the position of the connecting part.
The figure shows an item which is made in three versions. The core-pins are driven into the corresponding position
by two independently-controlled core puller plates.
Version A core puller plate 1 actuated
Version B core puller plate 2 actuated
Version C core puller plates 1+2 actuated
The core puller plates drive against fixed stops in the front and back position
and are controlled by proximity switches in both positions. This enables an integration into the control of the mould carrier.
The figure shows version A;
Core puller plate 1 is actuated.
Core puller plate 2 is not actuated.
The building height of the foam mould is limited by the mould carrier.
Due to the small and compact dimensions of the block cylinders the core puller plates could be installed in a space-saving way.