Automatic doors are familiar from hospitals, for example: after briefly pressing a button on the wall, the structure opens automatically, which is a great help when transporting beds, for example. Automatic door openers of a similar type can also be found in many companies and stores, at airports, as “airlocks” in research stations and in front of barrier-free toilets. A sophisticated gearbox usually operates inside them.
How exactly do electric door opener systems work?
First of all, a distinction must be made, as there are very different automatic door and gate systems – including swing, sliding and revolving doors. In most cases, various sensory equipment, an electric control unit and a drive unit including an electric motor and gearbox are used. If you are close to the door, this is registered by the sensory equipment and a signal is then transmitted to the motor control unit, which in turn sets the gearbox – and a linkage connected to it – in motion. This causes the door to open. At the same time, a closing spring is tensioned, which pulls the door closed again by mechanical means after a desired time window. The design has a safety device that interrupts the entire process if there is an obstacle in the door’s range of movement.
Electric motor and gear unit of an automatic door opener. EMAG offers gear cutting machines for the machining of frequently changing workpieces.
What characterizes the gearbox in the door operator?
Take the “swing door” as an example: its drive contains a multi-stage gearbox that significantly reduces the speed between the motor shaft and the output shaft. Planetary bevel, bevel-helical or helical gearboxes with just three stages are used here – any more stages would take up too much installation space, would be too expensive to produce and would often cause annoying noise. Automatic sliding doors in the entrance area of stores, for example, are characterized by a different design. They have to be very fast and quiet, which is achieved with rack and pinion gears or cable pulls.
The machining of small gears with a large variety of parts places high demands on gear hobbing machines. Areas of application: Milling of worms (electric motors), hobbing of straight and helical metal and plastic tooth profiles.
What other automated or motorized access systems and doors are available?
The field is indeed huge. Motors and gearboxes can be found, for example, in “passenger separators” in the entrance area of subway trains, in elevator doors and room partitions as well as in powered turnstiles and special windows. Depending on the area of application, manufacturers have to overcome different challenges – for example, protecting the “separator” from vandalism or the drive of a thermal door in a cold store from extreme temperatures. In addition, the continuous mechanical stress is very high because the systems are in use for a very long time at a high cycle rate – and, if possible, must never fail.
Automatic door systems simplify many processes, for example in hospitals. They are also subject to high continuous loads.
Do standards play a role?
There has been a European standard for the safety of automatic doors since 2013. It applies in all member states of the European Union – but only for new constructions built after this date. Among other things, this includes the regulations that the doors must be serviced at least once a year and that (daily) monitoring of their functions is the responsibility of the operator. In addition, there are even detailed regulations on how quickly an automated escape route door must open after a switch is pressed (within just three seconds).
What does the future hold?
The future of the door is keyless: private smart homes and commercial properties are increasingly using locking systems that can be opened by fingerprint, facial recognition, electronic PIN code entry or even by smartphone – thumbs and co. are replacing the front door key, which has the advantage, for example, that people’s access authorizations can be individually controlled and programmed. As a result, a cleaner, for example, only has access in the afternoon or the entire system is linked to time recording: when the employee enters the company through the outside door, “their” time starts automatically.
