This text is machine translated.
About electric cylinders
In machines and other mechanical systems, machine elements often have to be moved and positioned precisely. For example, pneumatic or hydraulic pressure cylinders are used as components of the drive technology, in which a piston is moved which performs the adjustment process of the parts to be driven. An alternative to this are electric cylinders, also known as electric lift cylinders, whose installation and operation is in many cases more advantageous and easier.
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How do electric cylinders work?
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What are electric cylinders used for?
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How are electric cylinders specified?
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What was to be taken into account when selecting and operating electric cylinders?
How do electric cylinders work?
An electric cylinder is an electric linear drive consisting of a threaded spindle driven by an electric motor, either via a gearbox or directly from a stepper motor. A nut is fitted on the threaded spindle which is connected to the tube-shaped connecting rod. If the spindle rotates, the nut and thus the connecting rod are retracted or extended depending on the direction of rotation . The connecting rod travel, the stroke, is limited by switches integrated at the ends of the travel, with which the motor is switched and a reversal of direction is triggered. Some electric cylinders have built-in Hall sensors or potentiometers to detect the position of the push rod. Alternatively, external switches and/or sensors, e.g. The position sensor, the connecting rod or the parts of the drive control to be moved, the feedback required for the desired positioning.
An important advantage of the electric cylinder is that it does not have to be supplied with electrical energy when it is in idle state, because it is a self-locking linear drive.
Electric cylinders with a motor and spindle are completely housed in one housing. (Picture: Festo)
What are electric cylinders used for?
Because electric cylinders, apart from a power connection, do not require complex infrastructure such as hydraulic or compressed air compressors as well as pressure lines and hoses, they can be used not only in the industrial environment, but also for many other applications. Due to their compact design, they can be easily and easily integrated into devices and machines . Electro-mechanically operated cylinders can be found not only in mechanical engineering, but also as actuators in agricultural machines, medical devices or products for the home or office sector. Examples of typical applications are systems for positioning and handling inside a machine or as a drive for adjusting beds in the hospital and nursing area as well as the remote-controlled adjustment option of beamers mounted on the ceiling of a conference room.
How are electric cylinders specified?
Electrical cylinder where the drive motor is mounted to the side. (Picture: Drive SystemEurope Ltd.)
The most important technical data for electric cylinders is the lift travel and the tensile and compressive force that the connecting rod can exert. The latter are given in N (Newton) . Because these properties depend on the respective requirements of the design environment, there is a wide range of different designs. In many cases, the speed at which the connecting rod can be moved in and out is also decisive. This is specified in mm/s or in m/s for fast electric cylinders. In addition, the recording of electrical power in the form of rated voltage and operating current is also specified in the data sheets. The electric cylinders offered are controlled primarily with low DC voltages in the range of less than 30 volts . The data sheets also specify the temperature range of the environment in which an electric cylinder may be operated.
What was to be taken into account when selecting and operating electric cylinders?
The design of the machine or device in which the electric cylinder is to be installed specifies its mechanical dimensions. Because these are compact, relatively little space has to be provided for their installation. In some electric cylinders, the motor is arranged in a row with the spindle, while others are on the side, was a shorter design. The decisive factor in selecting the material that makes up the electric cylinder is the environment in which it is operated. On standard versions, the connecting rod can be made of aluminum and the housing can be made of zinc alloy. Stainless steel versions are available for environments where aggressive media are used or where special hygiene requirements are required. The protection class of the electric cylinders must also comply with the requirements of the environment, e.g. IP 65, if they are exposed to water spray.
Electric cylinders are usually not designed for continuous operation because the actuating functions they are supposed to perform only need to be performed at the moment. The permissible operating mode is specified precisely in the data sheets, e.g. Duty cycle 25%, i.e. 1 minute of continuous operation and then 3 minutes of pause. If these limit values are exceeded, the drive can be overloaded and heat up impermissible. Especially in private environments, the noise level caused by operating an actuator also plays a role. For this purpose, there are particularly quiet versions which produce a sound level of less than 55 dB when operated.
As accessories for the electric cylinders, suitable brackets are offered for example separate position sensors.