Electric cylinder

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An electric lifting cylinder, which works on the principle of an axially movable coil (referred to in English as "Moving Coil Actuator")

Electric cylinders , also known as electric lifting cylinders , are adjustment units driven by an electric motor that can extend and retract a thrust tube linearly. Electric cylinders are a constructive alternative / addition to pneumatic cylinders and hydraulic cylinders . Electric cylinders are available in different sizes for different forces and areas of application. They belong to the group of electromechanical mechanical engineering components.

Electric cylinder guidelines

In terms of the EC Machinery Directive, the electric cylinder is a machine that is intended for subsequent installation in overall systems (Directive 98/37 / EC - Appendix II B). Furthermore, the EU directive on electromagnetic compatibility 89/336 / EEC applies. (As of January 2008)

technical description

An electric motor is used as the drive , which is usually coupled to a gearbox . The drive of the gearbox is connected to a threaded spindle via a coupling . A guide nut is driven by the threaded spindle, which in turn is firmly connected to the push tube. The thrust tube is extended and retracted by rotating the motor clockwise / counterclockwise. The thrust tube is supported and guided by the standpipe, which is firmly connected to the gearbox housing. The thrust tube movement (the stroke) is limited by integrated limit switches in the respective end position. Depending on the design, electric cylinders can be suitable for pulling and / or pushing forces.

Areas of application

The most common applications are in medical technology, agricultural technology, media technology and mechanical engineering. Since there are versions with a higher degree of protection (IP66), outdoor applications are possible.

In medical technology applications, electric cylinders are used to adjust nursing and hospital beds , examination tables, medical facilities such as radiation devices and X-ray systems, etc. (for this purpose, a medical test according to EN 60601-ff. Is usually required by the manufacturer). A typical field of application in the outdoor area is found in agricultural technology, for example as adjustment of auxiliary rods for fertilization and harvesting equipment, sieve adjustments for combine harvesters and cutting width settings. In seminar rooms as well as in the private sector, they are used to adjust beamers, displays and overhead projectors. In general mechanical engineering, electric cylinders are used to adjust the format of processing machines, as an actuator for additional units within machines and as remote-controlled manipulators in hazardous areas.

advantages

The most important elements of an electric cylinder (motor, gearbox, spindle, limit switch) are compactly combined in one design and therefore usually allow uncomplicated integration into overall designs. Installation is considered to be quite simple, as only power lines are required. This results in a cost advantage compared to air hoses for pneumatic cylinders and high-pressure hoses for hydraulic cylinders. Electric cylinders do not require any energy when they are at a standstill, as they usually have mechanical self-locking . This results in a further cost advantage, which can be classified as considerable depending on the frequency of use. The traversing movement can be adjusted continuously, so any position can be approached within the stroke length. The signals of the integrated limit switches can be executed and easily integrated into the control loop of a higher-level PLC control. Leakages, which are possible in principle with pneumatics and hydraulics, do not occur with electric cylinders due to the design.

disadvantage

Compared to pneumatic cylinders, the duty cycle is often limited. Only a few electric cylinders are designed for continuous operation. In addition, the speed of the push tube (the piston rod) is higher with pneumatic cylinders and better suited for short cycle times. Compared to hydraulic cylinders, the pulling / pushing force in electric cylinders is usually less high.

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