Direct Drive Bearings
Less is more
Franke wire race bearings with integrated direct drive give you highest energy efficiency. The integration of the motor directly to the bearing, makes it possible to entirely dispense components such as gear and drive pinion. The moving masses thus fall significantly lower – the power loss by factors such as friction and backlash is minimized.
Quick and accurat
Due to their special design bearings with direct drive offer clear advantages in terms of precision and dynamics:
The driving force in the bearing and the power transmission without further mechanical parts guarantees maximum positioning accuracy even at high speeds. Low moving masses and optimal weight distribution minimize friction or vibration.
Silent running even at high speed
Franke wire race bearings with direct drive feature smooth and silent runing even at high rotational speeds.
Maximum Performance – Space Saving Design
Direct drive bearings are particularly suitable for applications in which
high performance and small mounting space are important criteria. The
integration of the complete drive system into the bearing housing means
that components subject to heavy wear for the conventional transmission of
drive power such as toothed belts, shafts or chains can be omitted. This also
enables a more accurate positioning.
Advantages of Direct Drive Bearings
Your benefits when using direct drive bearings are:
- Low weight of the total system
- Space saving design
- Customized Design
- Integrated System, no further parts
- Wear-free drive
- High torque
- Highly dynamic movements, high efficiency
- motor, measuring system or controller are freely selectable
- Water-cooling on request (doubling the nominal torque)
Direct Drive Bearings in medical applications
Franke wire race bearings are the first choice for all well-known manufacturers of CT-scanners worldwide. Silent, light and highly dynamic they meet all requirements of modern components for cutting-edge medicine. Here, customers get the complete assembly of lightweight bearings, motor and control coordinated from a single source.
Direct integration into the bearing housing
In its highest configuration level Franke Wire race bearings are available as complete systems consisting of bearing, drive and control. The motor is integrated directly into the housing. The static bearing part carries the stator, the moving part works as the rotor of the electric drive. There are no additional components needed to mechanically set the bearing in transition which increases the efficiency of the system.
Through the use of housing parts made of aluminum, the weight of the motor can be more than compensated. A lightweight Franke bearing with direct drive is therefore still much lighter than a conventional steel bearing without drive. The small masses to be moved also ensure that the engine can be designed smaller and will operate with higher dynamics and speed. These are important benefits for example in applications such as indexing tables, filling stations or e-mobility.
For example: Indexing tables with direct drive bearings
An idexing table with double row wire race bearing and integrated direct drive system may have following specification:
|Regular torque Nm||40|
|Peak torque Nm||145|
|Measuring system||incremenal (inductive scan)|
|Total weight kg||19,5|
FAQs - Direct drive bearings
Torquemotors are integrated directly into Franke bearing assemblies. The customer receives a completely installed system. A gearbox is no longer required. With this system, it is not only possible to generate a rotational movement but also to position it or to execute definable steps.
A torquemotor consists of two components, the stator with coils and the rotor with permanent magnet. The current-flowing coils produce a time-variable electric field, which interacts with the constant magnetic field of the rotor. The resulting force is used to generate the torque. The Torquemotor allows high torque at a defined number of revolutions per minute. The distance between stator and rotor (air gap) is decisive for the magnitude of the torque. The preloaded Franke bearing ensures a constant air gap. A measuring system can be used to determine the motor position.
The cables are customized according to customer requirements.
– cable with plug – variable cable lengths
– cable open version with wire end ferrules – variable cable lengths
– plug attached to the bearing (according to customer request)
In order to protect the motors from thermal overload, they are permanently temperature-monitored. Temperature-dependent resistors are installed for this purpose. The following sensors are available:
– PTC thermistor (standard)
– Twilling switch (Klixon; bimetal switch)
The motors can optionally be operated with water cooling. This leads to a doubling of the nominal torque.
All measuring systems available on the market can be integrated into the bearing assembly. Very robust inductive measuring systems are used as standard. They are available as incremental or absolute systems in different accuracy classes. The following interfaces are available:
– incremental system: TTL, 1Vpp
– absolute system: EnDat 22; Fanuc, BiSS, SSI – 1Vpp
Absolute systems are i.d.R. 50% more expensive than incremental.
The (closed) measuring tape is attached directly to the rotor and the measuring head is screwed to the stator. It is also conceivable to attach a measuring system to the mating structure of the customer.
Since the measuring tape is a closed ring, only certain diameters are available, which must be taken into account during the design. For larger numbers, any diameter is available. Additional costs arise.
All motors are tested before delivery in accordance with the EC directive 73 / 23EWG and the standards EN 50178 and EN 60204.
A manual with general notes, safety instructions, connection diagrams and installation instructions are enclosed.
Bearings with direct drive are available from KK-Ø100 to 1800mm.
All controllers available on the market can be used.
Franke recommends servo drives. These are characterized by a high power density with intelligent functionality and a compact design. The controllers offer very good control characteristics as well as programming capability and support standard communication protocols. The servo drives have a complete digital motion controller and support a large number of commutation modes and position feedback. We would be pleased to propose the appropriate controller for the customer application and commission the complete system if required.
The motors are designed for a continuous temperature of up to 120 ° C. The bearing assembly work as standard up to 80 ° C and may have to be designed in a special way to meet higher temperatures.
This depends on the design of the bearing assembly and must be checked in each individual case. Standard bearings are, for example, not designed for permanent use under water and thus achieve a protection class of max. IP41.
The engine reduces speed slowly until it stops. Unless a phase shortfall is initiated over the performance part. Then the engine brakes relatively quickly. Alternatively, an additional braking system may be used.
No, because it must be fulfilled for the entire system and not for individual components only.
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