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EMAG offers perfect technology for making electric motor

  • 01-Jan-2019
  • Articles|Technical Articles


The company’s eldec induction technology is a perfect heating and hardening solutions for electric motor construction.
 
The e-boom is imminent. For example, the Center of Automotive Management (CAM) estimates that as early as 2025, around 15 percent of all new cars will have an electric drive. However, the slowly increasing e-motor volumes are already challenging production planners today. 
 
In many areas of application, they have to establish new production processes with which the components of the electric motors can be manufactured fast and reliably - an ongoing process in which the induction specialists from eldec are often involved. For example, induction heating’s full potential can be seen when heating a motor housing for joining, preheating rotor shafts before welding or hardening gear wheels. The process is faster, more precise and more reliable than any alternatives. In addition, it can be easily integrated into any production environment. Induction is a benefit for everybody involved.
 
High volumes, high precision, flexible production - these keywords have been describing everyday life in automotive engineering for decades. And, of course, they also provide the framework for the construction of electric motors. However, many electric cars are currently still produced in quantities that are hardly comparable with the usual figures in the automotive industry. The question is therefore: Which technology can be used to establish highly efficient and safe processes for much larger quantities?  It’s no coincidence that the answer often includes eldec's induction technology, as Jens Giering from eldec explains, “There are a large number of components in the electric motor, such as rotors, gear wheels or the stator, which are heated before joining or welding or which have to undergo a hardening process. For these applications, induction is the ideal technology."
 
Joining: Accurate heating protects the component
 
The example of joining (shrink fitting) illustrates how this looks in detail. In the production of electric motors, this process is ideal for creating an interference-fit connection between two components. For example, a rotor sheet stack could be heated to a temperature of 180 to 220°C by induction, and the rotor shaft can then be inserted into the rotor plate stack with little force. 
 
It is important that the rotor is not damaged in any way during heating and that no decolorizationof the metallic parts due to temperature takes place; therefore, a precise temperature is important. The ECO LINE generator from eldec plays a decisive role in this, with a generator output of 70 kW as an energy source for induction heating. The generator can be customised to best fit the individual tasks.
 
The frequency, power and field characterisation of the electromagnetic field is then adapted to the workpiece. Only a precisely defined area of the workpiece is actually heated between 180 and 220°C - and this to an equally precisely defined degree. 
 
In addition, there is a demand for process speed with many components. In the case of the rotor plate stack, the heating time lasts only 90 seconds. Incidentally, induction technology is also used in a similar way when heating a motor housing to join the stator or when heating gear wheels for joining to shafts. “A decisive quality is always the fact that our technology can be easily integrated into larger, more complex production systems. For this purpose, we can customise  the equipment from the oscillating circuit via the generator control system - which also includes the interfaces to the customer's main cell controller or technology - to single or multiple outputs," adds Giering.  
 
Hardening: Perfectly integrated into the production flow
 
Eldec's integrated MIND hardening machines with their main components basic machine, energy source, inductor, coolant system and automation are of great interest to users in the construction of electric motors. By using different frequencies, the integrated system guarantees a hardness pattern according to customer requirements, on parts like gear wheels or rotor shafts for example. The heating takes place in the desired hardness range and lasts only two to three seconds for the gear wheel and 1.3 seconds for the rotor shaft. 
 
The key factor here is that the MIND machine is modularly designed depending on the workpiece dimensions and the desired hardness profile - eldec's equipment interferes well with preceding and subsequent machining steps. “For this reason, the system is always available as a hand-loaded stand-alone solution or as a hardening cell with linear cycle capability, which can be loaded by robot or a gantry. The hardening machine is then an integral part of the production process," confirms Giering.
 
Enquiries from the construction of electric motors are increasing
 
Two final examples show how variable the eldec technology can be used in electric motor construction with an ECO LINE generator from eldec with an output of 30 kW: heating the entire stator to a temperature of 110 to 130°C before impregnation process of motor winding and Induction preheating for welding - for parts such as rotor shafts -  Weld preheating is important from any production processes because it effectively prevents cracking of the component at high welding temperatures. 
 
As expected, due to the rise of electromobility the number of enquiries from the electric motor industry is increasing almost monthly. “At the same time, our technology is already being used in a wide range of applications in the industry. We are ideally prepared for this development because we have the experience to heat, harden or anneal complex components. In the end, induction provides the customer with a highly efficient and safe production process," says Giering.
 


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