Production and cutting cores from non crystal, amorphous materials to magnetic circuits of rotating electric machines.

The invention regards methods of production an electric rotating machines from non crystal (amorphous) magnetic materials.

A primary object of the invention regards lamination and cutting of magnetic material to parts with profiles required for production magnetic circuits of rotating electric machines and using invented methods to existing and to new construction of electric machines.

Amorphous magnetic materials, also known as non crystal magnetic materials or magnetic glasses, are currently produced by Allied Corporation in US and Japan, by and Vacuumschmelze GMBH in Germany. They are made as a very thin (0.017 to 0.05 mm), one side oxidised ribbon, according to the United States Patent No. 4,298,382.

Their core losses are ten times lower than conventional silicon steel and they are the best for application to cores of electric machines (motors, generators and transformers) [2]. These materials are generally known as Metglas.

At the ribbon stage amorphous materials are not suitable to produce stacked core of transformers and electric rotating machines. Ribbons of amorphous materials are compacted to wound cores or to strips. They could be hot compacted according to US

Patent No. 4,529,458 by the method of pressure and thermal diffusion.

Hot compacted strips are known as Powercore strips. The Powercore strips are very thin (0.2 mm) and extremely brittle. They are cut on 90 and 45 degree only. [4]

Due to reduction of eddy current, process of production standard electric machines from silicon steel requires, assembling the cores from thin (0.3 to 0.5 mm) singular cut strips.

Such technology is not required to produce cores from amorphous magnetic materials. Amorphous materials are produced as very thin 0.017 to 0.035 mm ribbon with

resistivity from 123 to 142 (u-ohm-cm), therefore eddy current in singular ribbon are reduced almost to zero. Insulation of a adhesive material and of the oxidise of the ribbon prevent to spread eddy current in laminated strips.

Ribbons were bonded by special adhesive material. Ardalite F with Hardener 905 made by Ciba Geigy were found as the best materials for lamination these ribbons to magnetic cores of electric rotating machines. Glue is spread between ribbons of the compacted material. Total stack is compressed and baked below recrystalisation temperature.

Cores are very rigid and brittle with lamination factor higher than 0.825. They are easy for handling and assembling.

Amorphous materials are extremely hard (800 to 1100 in Vickers Scale) and it was a main reason which prevented them from using it as a magnetic circuits in electric rotating machines. Standard cutting methods, for example the guillotine or blank die are not suitable for cutting amorphous materials. The material is mechanically stressed and cracks. Laser and EDM cutting methods melt the amorphous material and cause of undesirable crystallization.

Additionally, these methods make undesirable connection between separated amorphous ribbons in laminated plates, strips and cores. These connections cause of eddy current and additional losses of energy.

Australian Patent No. 623981 gives method of cutting amorphous materials, on a various shapes, in ambient temperature without cracking, melting and undesirable crystallization and without connections between separated amorphous ribbons in laminated plates, strips and cores.

Method described in PCT/AU 95/00048 patent application gives 3 dimensional method of cutting completely assembled cores of electric machines, by inclining cutting head or inclining cutting material. The invention regards to methods of producing electric rotating machines on disk construction. As example was considered core of asynchronous disk motor currently produced by Fishbach GMBH in Germany. Stator and rotor of such machines are wound from singular ribbon. Skewed slots are cut before wound of cores. The construction of magnetic cores of Fishbach's motors is schematically shown on figure 1. Slots (2) were cut on one side of magnetic core (1). Machines could be collected with two or more stators and rotors.

New method of production disk machines is presented below. Cores of stators and rotors are wound before cutting its slots. Each layer are bonded together by adhesive non gas producing material. Completely assembled cores are cut using 3 dimensional cutting method described in PCT/AU 95/00048 patent application I n case of using amorphous material eg. Metglas ribbons are bonded by Ardalite F and Hardener 904 produced by Ciba Geigy.

General view of the modular machine is presented on figure 2 and described as follows : (1) rotor or rotors, (2) stator or stators, (3) draft shaft. Rotors and stators are based on wound core. They are made from silicon steel and/or from amorphous material. Skewed slots are cut on a a one and/or both sides of cores. Teeth of core presented on figure 1 have not the same area of its cross section and triangle longitudinal section. They are cause of undesirable saturation of magnetic density in teeth and non uniform magnetic density in the air gap of the machine. The invention presents construction cores of rotating electric machines where above disadvantages do not exist. To assist with understanding this invention reference will be made to accompanying with the drawings.

Figure 1 presents core made by conventional cutting method. Figure 3 presents core that was cut after assembling the core. Skewed slots (1) have the same cross section area and its teeth (2) have the same cross section area and the same profile. Longitudinal teeth sections are rectangular. Air gap (3) has not to be placed perpendicularly to the rotating axle. Such placement makes bigger active machine length and reduce copper losses. Machine has bigger power and efficiency. Figure 4 presents two shapes cross section shapes of such rotating machines. Teeth have rectangular profiles in both cases.

Reduction weight of modular electric machines.

Figure 5 presents machine with two double side skewed stator (1), assembled on the common draft (3) shaft with two rotors (2). In each separated machine lines of magnetic flux is shown on figure 6 curve 1.

The machine can be wound by any required electrical winding, as DC, AC single or 3 phase. The machine contains more than one stators and rotors assembled on a common draft shaft is named "Modular Electric Machine". When electrical winding of two adjacent stators, or rotors are rotated by 180 electrical degree as shown on figure 7 a value of the magnetic flux in the middle joke (eg. joke of stator) is equal zero. Such lines of magnetic flux are shown on figure 7 as curves 2

Construction of the machine after joke reduction is shown on figures 8 and 9. Line of magnetic flux is shown as curve 3. The method was successfully found in construction cores of 3 phases 3 kW modular amorphous motor contains two stator and two rotors. Small yoke in stator was left only due to mechanical construction. Weight of cores were reduced to about 70°_. After using more stators and rotors in construction the modular machine, the machine's cores weight is reduced to the its teeth plus two outside yokes practically. Teeth weight do not exceed 40 % of the total core weight, therefore weight of the modular machines are reduced to 45 - 50 % in comparison with other electric machines.

Length of magnetic field in the modular yokels machines is much shorter as shown on figures 7 and 8, therefore they have higher saturation factor and requires lower magnetisation current They have higher power factor and they are more efficient. Above method is suitable for any electric rotating machine based on disk cores.